Author: "Engels R" / Topic: nuclear experiment (nucl-ex) - Searchworks@Jio Institute Digital Library Search Results

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37 results on '"Engels R"'

1. A high-density polarized 3He gas-jet target for laser-plasma applications

Author: Fedorets, P., Zheng, C., Engels, R., Engin, I., Feilbach, H., Giesen, U., Glückler, H., Kannis, C., Klehr, F., Lennartz, M., Pfeifer, H., Pfennings, J., Schneider, C. M., Schnitzler, N., Soltner, H., Swaczyna, R., and Büscher, M.
Subjects: Physics - Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: A laser-driven spin-polarized 3He2+ beam source for nuclear-physics experiments and for the investigation of polarized nuclear fusion demands a high-density polarized 3He gas-jet target. Such a target requires a magnetic system providing a permanent homogeneous holding field for the nuclear spins plus a set of coils for adjusting the orientation of the polarization. Starting from a transport vessel at a maximum pressure of 3 bar, the helium gas is compressed for a short time and can be injected into a laser-interaction chamber through a non-magnetic opening valve and nozzle, thus forming jets with densities of about a few 10^19 cm-3 and widths of about 1 mm. The target comprises a 3D adjustment system for precise positioning of the jet relative to the laser focus. An auxiliary gas system provides remote target operation and flushing of the gas lines with Ar gas, which helps to reduce polarization losses. The design of the target, its operation procedures and first experimental results are presented., Comment: 12 pages, 20 figures, submitted to PRAB
Published: 2022
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2. Search for the $��$ mesic $^3$He in the $pd\rightarrow d p ��^{0}$ reaction with the WASA-at-COSY facility

Author: Adlarson, P., Augustyniak, W., Bashkanov, M., Bass, S. D., Bergmann, F. S., Berlowski, M., Bondar, A., Buscher, M., Calen, H., Ciepal, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Fohl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Heijkenskjold, L., Hejny, V., Husken, N., Hirenzaki, S., Johansson, T., Kamys, B., Kelkar, N. G., Kemmerling, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Ritman, J., Roy, A., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroher, H., Szczurek, A., Wolke, M., Wronska, A., Wustner, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Zlomanczuk, J., and Zurek, M.
Subjects: Nuclear Theory, High Energy Physics::Phenomenology, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The excitation function for the $pd\rightarrow$ $d p ��^{0}$ reaction has been measured by WASA-at-COSY experiment with the aim of searching for $^{3}\hspace{-0.03cm}\mbox{He}$-$��$ mesic nuclei. The measurement in the vicinity of $��$ meson production was performed using a ramped proton beam. The data analysis and interpretation was carried out with the assumption that the $��$-mesic Helium decays via the formation of an intermediate N$^{*}$(1535) resonance. No direct signal of the $��$-mesic nucleus is observed in the excitation function. We determine a new improved upper limit for the total cross section for the bound state production and decay in the $pd\rightarrow$ $(^{3}\hspace{-0.03cm}\mbox{He}$-$��)_{bound} \rightarrow$ $d p ��^{0}$ process. It varies between 13 nb to 24 nb for the bound state with width in the range $��\in (5,50)$ MeV.
Published: 2020
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3. Study of Three-Nucleon Dynamics in the dp Breakup Collisions using the WASA Detector

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bondar, A., Buscher, M., Calen, H., Ciepal, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Fohl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Heijkenskjold, L., Hejny, V., Husken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Morsch, H. -P., Moskal, P., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Ritman, J., Roy, A., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroher, H., Szczurek, A., Trzcinski, A., Wolke, M., Wronska, A., Wustner, P., Yamamoto, A., Zabierowski, J., Zieli, M. J., Zlomanczuk, J., Zupranski, P., Zurek, M., Deltuva, A., Golak, J., Kozela, A., Skibinski, R., Skwira-Chalot, I., and Witala, H.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Differential cross section for the 1H(d,pp)n breakup reaction at deuteron beam energy of 340 MeV has been measured with the use of WASA detector at COSY-Juelich. The set of proton-proton coincidences registered at Forward Detector has been analysed on dense grid of kinematic variables, giving in total around 5600 data points. The cross section data are compared to theoretical predictions based on the state-of-the-art nucleon-nucleon potentials, combined with three-nucleon force, Coulomb interaction or carried out in a relativistic regime.
Published: 2019

4. Search for eta mesic 3He with the WASA-at-COSY facility in the pd-> 3He 2gamma and pd-> 3He 6gamma reactions

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bass, S. D., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Heijkenskj��ld, L., Hejny, V., Hirenzaki, S., Jarczyk, L., Johansson, T., Kamys, B., Kelkar, N. G., Kemmerling, G., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Ritman, J., Roy, A., Rundel, O., Sawant, S., Schadmand, S., Sch��tti--Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics::Phenomenology, Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: We report on the experimental search for the bound state of an $��$ meson and $^{3}\hspace{-0.03cm}\mbox{He}$ nucleus performed using the WASA-at-COSY detector setup. In order to search for the $��$-mesic nucleus decay, the $pd\rightarrow$ $^{3}\hspace{-0.03cm}\mbox{He} 2��$ and $pd\rightarrow$ $^{3}\hspace{-0.03cm}\mbox{He} 6��$ channels have been analysed. These reactions manifest the direct decay of $��$ meson bound in $^{3}\hspace{-0.03cm}\mbox{He}$ nucleus. This non-mesonic decay channel has been considered for the first time. When taking into account only statistical errors, the obtained excitation functions reveal a slight indication for a possible bound state signal corresponding to an $^3$He-$��$ nucleus width $��$ above 20 MeV and binding energy $B_s$ between 0 and 15 MeV. However, the determined cross sections are consistent with zero in the range of the systematic uncertainty. Therefore, as final result we estimate only the upper limit for the cross section of the $��$-mesic $^{3}\hspace{-0.03cm}\mbox{He}$ nucleus formation followed by the $��$ meson decay which varies between $2$ nb and $15$ nb depending on possible bound state parameters., Article accepted to be published in PLB
Published: 2019
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5. On the Production of an Isotensor Dibaryon in the $pp \to pp��^+��^-$ Reaction

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Marciniewski, P., Maria��ski, B., Morsch, H. --P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti--Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: Exclusive measurements of the quasi-free $pp \to pp��^+��^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $T_p = 1.08 - 1.36$ GeV ($\sqrt s$ = 2.35 - 2.46 GeV), which includes the regions of $N^*(1440)$ and $��(1232)��(1232)$ resonance excitations. Calculations describing these excitations by $t$-channel meson exchange are at variance with experimental differential cross sections and underpredict substantially the measured total cross section. An isotensor $��N$ dibaryon resonance with $I(J^P) = 2(1^+)$ produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong and more recently calculated by Gal and Garcilazo.
Published: 2018
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6. Backward single-pion production in the $\boldsymbol{pd\rightarrow {}^3\textrm{He}\,��^0}$ reaction with WASA-at-COSY

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. --P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., and Wilkin, C.
Subjects: Nuclear Theory (nucl-th), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: New data on the production of single neutral pions in the $pd\rightarrow{}^3\textrm{He}\,��^0$ reaction are presented. For fifteen proton beam momenta between $p_p=1.60\;\textrm{GeV}/c$ and $p_p=1.74\;\textrm{GeV}/c$, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum., 9 pages, 5 figures, 3 tables submitted to EPJA
Published: 2018
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7. An Isotensor Dibaryon in the $pp \to pp��^+��^-$ Reaction?

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Marciniewski, P., Maria��ski, B., Morsch, H. --P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti--Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: Exclusive measurements of the quasi-free $pp \to pp��^+��^-$ reaction have been carried out at WASA@COSY by means of $pd$ collisions at $T_p$ = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region $T_p = 1.08 - 1.36$ GeV, which is the region of $N^*(1440)$ and $��(1232)��(1232)$ resonance excitations. Calculations describing these excitations by $t$-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor $��N$ dibaryon resonance with $I(J^P) = 2(1^+)$ produced associatedly with a pion is able to overcome these deficiencies., arXiv admin note: substantial text overlap with arXiv:1803.03192
Published: 2018
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8. Response of a Li-glass/multi-anode photomultiplier detector to $��$-particles from $^{241}$Am

Author: Rofors, E., Perrey, H., Jebali, R. Al, Annand, J. R. M., Boyd, L., Clemens, U., Desert, S., Engels, R., Fissum, K. G., Frielinghaus, H., Gheorghe, C., Hall-Wilton, R., Jaksch, S., Jalg��n, A., Kanaki, K., Kemmerling, G., Maulerova, V., Mauritzson, N., Montgomery, R., Scherzinger, J., and Seitz, B.
Subjects: Physics::Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment (nucl-ex)
Abstract: The response of a position-sensitive Li-glass scintillator detector to $��$-particles from a collimated $^{241}$Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 X 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector., 23 pages, 7 figures, to be submitted to Nuclear Instruments and Methods in Physics Research Section A
Published: 2018
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9. Total and differential cross sections of $��$-production in proton-deuteron fusion for excess energies between $Q_��=13\;\text{MeV}$ and $Q_��=81\;\text{MeV}$

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawanta, S., Schadmand, S., Sch��tti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., and Wilkin, C.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: New data on both total and differential cross sections of the production of $��$ mesons in proton-deuteron fusion to ${}^3\text{He}\,��$ in the excess energy region $13.6\;\text{MeV}\leq Q_��\leq 80.9\;\text{MeV}$ are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum J��lich, using a proton beam at 15 different beam momenta between $p_p = 1.60\;\text{GeV}/c$ and $p_p = 1.74\;\text{GeV}/c$. While significant structure of the total cross section is observed in the energy region $20\;\text{MeV}\lesssim Q_��\lesssim 60\;\text{MeV}$, a previously reported sharp variation around $Q_��\approx 50\;\text{MeV}$ cannot be confirmed. Angular distributions show the typical forward-peaking that was reported elsewhere. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a large interval., 8 pages, 7 figures, preprint submitted to Physics Letters B
Published: 2018
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10. Isoscalar Single-Pion Production in the Region of Roper and $d^*(2380)$ Resonances

Author: Collaboration, WASA-at-COSY, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berłowski, M., Bhatt, H., Bondar, A., Büscher, M., Calen, H., Ciepał, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Föhl, K., Fransson, K., Goldenbaum, F., Grigoryev, A. Goswami K., Gullström, C. -O., Heijkenskjöld, L., Hejny, V., Hüsken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krzemien, W., Kulessa, P., Kupsc, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schätti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Ströher, H., Szczurek, A., Trzcinski, A., Varma, R., Wolke, M., Wronska, A., Wüstner, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Złomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: Single-pion production, Nuclear Theory, FOS: Physical sciences, p deuteron, Juelich COSY PS, pi: production, energy dependence, High Energy Physics - Experiment, mass spectrum, Single-pion, High Energy Physics - Experiment (hep-ex), Roper resonance, Astronomi, astrofysik och kosmologi, Isoscalar part, isoscalar, excited state, Astronomy, Astrophysics and Cosmology, angular distribution, ddc:530, WASA, Nuclear Experiment (nucl-ex), Nuclear Experiment, Monte Carlo, total cross section, N(1440), Delta(1232), Dibaryon resonance, lcsh:QC1-999, dibaryon, differential cross section, branching ratio, particle identification, lcsh:Physics, experimental results
Abstract: Exclusive measurements of the quasi-free $pn \to pp\pi^-$ and $pp \to pp\pi^0$ reactions have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $T_p = 0.95 - 1.3$ GeV ($\sqrt s$ = 2.3 - 2.46 GeV), which includes the regions of $\Delta(1232)$, $N^*(1440)$ and $d^*(2380)$ resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below $T_p$ = 1 GeV. We observe a substantial increase of this cross section above 1 GeV, which can be related to the Roper resonance $N^*(1440)$, the strength of which shows up isolated from the $\Delta$ resonance in the isoscalar $(N\pi)_{I=0}$ invariant-mass spectrum. No evidence for a decay of the dibaryon resonance $d^*(2380)$ into the isoscalar $(NN\pi)_{I=0}$ channel is found. An upper limit of 90 $\mu$b (90 $\%$ C.L.) corresponding to a branching ratio of 5 $\%$ has been deduced., Comment: erratum: the upper limit for the branching ratio of the decay $d^*(2380) \to (NN\pi)_{I=0}$ is a factor of two smaller than given in the previous version of this article
Published: 2017
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11. Spin dependence of �� meson production in proton-proton collisions close to threshold

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bass, S. D., Bergmann, F. S., Berlowski, M., Bondar, A., Buscher, M., Calen, H., Ciepal, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Fohl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstrom, C. -O., Heijkenskjold, L., Hejny, V., Husken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schatti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Szczurek, H. Stroher A., Trzcinski, A., Wolke, M., Wronska, A., Wustner, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Zlomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high degree of the polarized proton beam of COSY, the reaction pp{\to} pp�� has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than one order of magnitude with respect to previous results allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q = 15 MeV signaling s wave production with no evidence for higher partial waves. At Q = 72 MeV the data reveals strong interference of P s and P p partial waves and cancellation of (P p) and Ss*Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the �� meson., Accepted for publication in Phys. Rev. Lett
Published: 2017
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12. Rapid fluctuation of the tensor polarization of deuteron beams behind carbon foils and their relation to the resonances in the isospin-breaking $^{12}{\rm C}(d,��_{2})^{10}{\rm B}^{*}$ reaction

Author: Seyfarth, H., Rouba, A., Baryshevsky, V., Engels, R., Grigoryev, K., Rathmann, F., and Str��her, H.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: Rapid fluctuations are observed in the tensor-polarization $p_{zz}$ of deuteron beams forward-transmitted through graphite targets. Unpolarized 9.50 to 18.60\,MeV beams from the K��ln tandem accelerator were utilized, and the polarization behind seven 36 to 188\,mg/cm$^{2}$ targets was measured with a polarimeter based on the $^{3}{\rm He}(\vec{d},p)^{4}{\rm He}$ reaction. Due to the chosen relation between the areal target densities and the initial beam energies $E_{\rm in}$, the seven sets of $p_{zz}(E_{\rm in})$ can be combined in a common plot as a function of $E_{\rm in}$. This allows one to understand $p_{zz}$, measured behind the 188\,mg/cm$^{2}$ target at $E_{\rm in}$=18.6\,MeV, as resulting from the sequence of differential polarization production $��p_{zz}(E)/��E$ during energy degradation in the target from $E$=18.60 to 9.50\,MeV. The rapid fluctuations of $��p_{zz}(E)/��E$$p_{zz}$ are described by 51 Gaussian-distributed cross-sections removing deuterons either in the $m=0$ or in the $m=\pm 1$ state from the beam. The 51 fitted central energies $E_{0}$ with a single exception agree with the energies of the narrow peaks in the excitation functions of the weak, isospin-breaking $^{12}{\rm C}(d,��_{2})^{10}{\rm B}^{*}(1.74\,{\rm MeV},J^��=0^{+},T=1)$ reaction with population of the second excited $^{10}{\rm B}$ state via intermediate excited $^{14}$N states. Strong evidence is found that removal of deuterons in the $m=0$ ($m=\pm 1$) state from the beam leads to the formation of $^{14}$N states of established positive (negative) parity. As an application, the removal cross-section functions allow to calculate $p_{zz}$ achievable with carbon targets for initial beam energies $E_{\rm in}$ between 18.60 and 9.50\,MeV and $E_{\rm out}$ given by the areal target density. Carbon layers in a sandwich technique would enable $p_{zz}$ between -0.4 and +0.3., 25 pages, 11 figures, 4 tables
Published: 2017
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13. Importance of d-wave contributions in the charge symmetry breaking reaction $dd \to {}^4\text{He}��^0$

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., Parol, W., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction $dd \to {}^4\text{He}��^0$ using the WASA-at-COSY detector setup at an excess energy of $Q = 60$ MeV. The determined differential cross section can be parametrized as $\text{d}��/\text{d}��= a + b\cos^{2}��^*$, where $��^*$ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are $a = \left(1.55 \pm 0.46 (\text{stat}) ^{+0.32}_{-0.8} (\text{syst}) \right)$ pb/sr and $b = \left(13.1 \pm 2.1 (\text{stat}) ^{+1.0}_{-2.7} (\text{syst})\right)$ pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the $��$ isobar to the $dd \to {}^4\text{He}��^0$ reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions., 5 figures
Published: 2017
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14. Concept for a time-of-flight Small Angle Neutron Scattering instrument at the European Spallation Source

Author: Jaksch, S., Martin-Rodriguez, D., Ostermann, A., Jestin, J., Pinto, S. Duarte, Bouwman, W. G., Uher, J., Engels, R., Kemmerling, G., Hanslik, R., and Frielinghaus, H.
Subjects: Physics, Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Scattering, business.industry, Detector, Solid angle, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Polarizer, Small-angle neutron scattering, Neutron time-of-flight scattering, law.invention, Optics, law, Spallation, Neutron, Nuclear Experiment (nucl-ex), business, Nuclear Experiment, Instrumentation
Abstract: A new Small Angle Neutron Scattering instrument is proposed for the European Spallation Source. The pulsed source requires a time-of-flight analysis of the gathered neutrons at the detector. The optimal instrument length is found to be rather large, which allows for a polarizer and a versatile collimation. The polarizer allows for studying magnetic samples and incoherent background subtraction. The wide collimation will host VSANS and SESANS options that increase the resolution of the instrument towards um and tens of um, respectively. Two 1m2 area detectors will cover a large solid angle simultaneously. The expected gains for this new instrument will lie in the range between 20 and 36, depending on the assessment criteria, when compared to up-to-date reactor based instruments. This will open new perspectives for fast kinetics, weakly scattering samples, and multi-dimensional contrast variation studies., 18 pages, 10 figures
Published: 2014
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15. Measurement of the $\vec{n}p \to d��^0��^0$ Reaction with Polarized Beam in the Region of the $d^*(2380)$ Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Calen, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lawani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, . P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., del Rio, E. Perez, Piskunov, N. M., Prashun, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti--Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: We report on a high-statistics measurement of the most basic double pionic fusion reaction $\vec{n}p \to d��^0��^0$ over the energy region of the $d^*(2380)$ resonance by use of a polarized deuteron beam and observing the double fusion reaction in the quasifree scattering mode. The measurements were performed with the WASA detector setup at COSY. The data reveal substantial analyzing powers and confirm conclusions about the $d^*$ resonance obtained from unpolarized measurements. We also confirm the previous unpolarized data obtained under complementary kinematic conditions.
Published: 2016
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16. Measurement of the $��\to ��^+ ��^- ��^0$ Dalitz plot distribution

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Morsch, H. -P., Moskal, P., Ohm, H., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sch��tti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Z��oma��czuk, J., ��upra��ski, P., ��urek, M., Kubis, B., and Leupold, S.
Subjects: FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Using the production reactions $pd\to {}^3\mbox{He}\,��$ and $pp\to pp��$, the Dalitz plot distribution for the $��\to ��^+ ��^- ��^0$ decay is studied with the WASA detector at COSY, based on a combined data sample of $ (4.408\pm 0.042) \times 10^4$ events. The Dalitz plot density is parametrised by a product of the $P$-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables $Z$ and $��$. For the first time, a deviation from pure $P$-wave phase space is observed with a significance of $4.1��$. The deviation is parametrised by a linear term $1+2��Z$, with $��$ determined to be $+0.147\pm0.036$, consistent with the expectations of $��$-meson-type final-state interactions of the $P$-wave pion pairs., 8 pages, 7 figures
Published: 2016
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17. Search for eta-mesic 4He in the dd->3He n pi0 and dd->3He p pi- reactions with the WASA-at-COSY facility

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Bondar, A., Buescher, 9 M., Calen, H., Ciepal, I., Clement, H., Czerwinski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstroem, C. -O., Heijkenskjoeld, L., Hejny, V., Huesken, N., Jarczyk, L., Johansson, T., Kamys, B., Kelkar, N. G., Kemmerling, G., Khatri, G., Khoukaz, A., Khreptak, O., Kirillov, D. A., Kistryn, S., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Morsch, H. -P., Moskal, P., Ohm, H., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Schaetti-Ozerianska, I., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Trzcinski, A., Varma, R., Wolke, M., Wronska, A., Wuestner, P., Yamamoto, A., Zabierowski, J., Zielinski, M. J., Zlomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: The search for 4He-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd->3He n pi0 and dd->3He p pi- processes. The beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd->4He eta reaction ranging from Q=-70 MeV to Q=30 MeV. The luminosity was determined based on the dd->3He n reaction and quasi-free proton-proton scattering via dd->pp n_spectator n_spectator reactions. The excitation functions determined independently for the measured reactions do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd->(4He-eta)_bound->3He n pi0 and dd->(4He-eta)_bound->3He p pi- processes were determined taking into account the isospin relation between both the channels considered. The results of the analysis depend on the assumptions of the N* momentum distribution in the anticipated mesic-4He. Assuming as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in 4He, we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for npi0 and ppi- channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N*-3He nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for npi0 and ppi- channels respectively., This article will be submitted to JHEP
Published: 2016
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18. Measurements of Branching Ratios for $��$ Decays into Charged Particles

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Heijkenskj��ld, L., Hejny, V., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khatri, G., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Prasuhn, D., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Rundel, O., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Sitterberg, K., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wiedner, U., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The WASA-at-COSY experiment has collected $3\times10^{7}$ events with $��$-mesons produced via the reaction $pd\rightarrow{^{3}\textrm{He}}��$ at $\textrm{T} = 1.0 \textrm{GeV}$. Using this data set, we evaluate the branching ratios of the decays $��\to��^{+}��^{-}��$, $��\to e^{+}e^{-}��$, $��\to��^{+}��^{-}e^{+}e^{-}$ and $��\to e^{+}e^{-}e^{+}e^{-}$. The branching ratios are normalized to the $��\rightarrow��^{+}��^{-}��^{0}$ decay. In addition an upper limit on a $CP$-violating asymmetry in $��\rightarrow ��^{+}��^{-}e^{+}e^{-}$ is extracted.
Published: 2015
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19. ABC effect and resonance structure in the double-pionic fusion to $^{3}He$

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, High Energy Physics - Experiment
Abstract: Exclusive and kinematically complete measurements of the double pionic fusion to $^{3}He$ have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY (the cooler synchrotron at Forschungszentrum Jülich). Similar to the observations in the basic $pn \rightarrow d \pi^{0} \pi^{0}$ reaction and in the $dd \rightarrow ^{4} He \pi^{0} \pi^{0}$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Differential cross sections are well described by the hypothesis of $d^{\ast}$ resonance formation during the reaction process in addition to the conventional t-channel $\Delta \Delta$ mechanism. The deduced $d^{\ast}$ resonance width can be understood from collision broadening due to Fermi motion of the nucleons in initial and final nuclei.
Published: 2015

20. Measurement of the $np \to np��^0��^0$ Reaction in Search for the Recently Observed $d^*(2380)$ Resonance

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: Exclusive measurements of the quasi-free $np \to np��^0��^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated $d^*(2380)$ resonance. Adding the $d^*$ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of F��ldt and Wilkin as well Albadajedo and Oset. The ABC effect, {\it i.e.} the low-mass enhancement in the $��^0��^0$-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.
Published: 2014
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21. Neutron-Proton Scattering in the Context of the $d^*$(2380) Resonance

Author: Adlarson, P., Augustyniak, W., Clement, H., Zabierowski, J., Zieliński, M. J., Zink, A., Złomańczuk, J., Żuprański, P., Żurek, M., Workman, R. L., Briscoe, W. J., Strakovsky, I. I., WASA-at-COSY Collaboration, Coderre, D., Czerwiński, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., Bardan, W., Föhl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullström, C.-O., Hauenstein, F., Heijkenskjöld, L., Hejny, V., Bashkanov, M., Hodana, M., Höistad, B., Hüsken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Bergmann, F. S., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., Kłos, B., Krapp, M., Krzemień, W., Kulessa, P., Kupść, A., Lalwani, K., Berłowski, M., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Mariański, B., Mikirtychiants, M., Morsch, H.-P., Moskal, P., Ohm, H., Bhatt, H., Ozerianska, I., Perez del Rio, E., Piskunov, N. M., Podkopał, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Büscher, M., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Calén, H., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, Hans, Szczurek, A., Ciepał, I., Täschner, A., Trzciński, A., Varma, R., Wagner, G. J., Wolke, M., Wrońska, A., Wüstner, P., Wurm, P., Yamamoto, A., and Yurev, L.
Subjects: Np Elastic-Scattering, Nuclear and High Energy Physics, Nucleon-Scattering, Partial wave analysis, Nuclear Theory, Hexaquark, Analyzing Power, FOS: Physical sciences, Context (language use), Double-Pionic Fusion, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Proton scattering, Neutron, ddc:530, Nuclear Experiment (nucl-ex), Nuclear Experiment, Partial-Wave Analysis, Physics, Elastic scattering, Scattering, Total Cross-Section, Resonance (chemistry), Intermediate Energies, Isospin Decomposition, Delta-Sigma-T, Spin Observables
Abstract: New data on quasifree polarized neutron-proton scattering in the region of the recently observed $d^{\ast}$ resonance structure are obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details the determination of the beam polarization, checks of the quasifree character of the scattering process, on all obtained $A_{y}$ angular distributions and on the new partial-wave analysis, which includes the new data producing a resonance pole in $^{3}D_{3}−^{3}G_{3}$ coupled partial waves at (2380 $\pm$ 10−i40 $\pm$ 5) MeV—in accordance with the $d^{\ast}$ dibaryon resonance hypothesis. The effect of the new partial-wave solution on the description of total and differential cross-section data as well as specific combinations of spin-correlation and spin-transfer observables available from COSY-ANKE measurements at $T_{d}$=2.27 GeV is discussed.
Published: 2014
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22. Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hodana, M., H��istad, B., H��sken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., K��os, B., Kleines, H., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Ohm, H., Ozerianska, I., Passfeld, A., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: We present new data for angular distributions and on the cross section ratio of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q = 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum J��lich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between Q = 20 MeV and Q = 60 MeV, which might indicate the variation of the production mechanism within this energy interval., 9 pages, 9 figures
Published: 2014
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23. Charge Symmetry Breaking in dd->4He��0 with WASA-at-COSY

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., H��istad, B., H��sken, N., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yurev, L., Zabierowski, J., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He��0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production., 14 pages, 5 figures
Published: 2014
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24. Measurement of the $��\to��^+��^-��^0$ Dalitz plot distribution

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, A., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hodana, M., H��istad, B., H��sken, N., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Kleines, H., K��os, B., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Martemyanov, B. V., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Sefzick, T., Serdyuk, V., Shwartz, B., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., T��schner, A., Trzci��ski, A., Varma, R., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zink, A., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Dalitz plot distribution of the $��\to��^+��^-��^0$ decay is determined using a data sample of $1.2\cdot 10^7$ $��$ mesons from $pd\to ^3\textrm{He}��$ reaction at 1 GeV collected by the WASA detector at COSY., 13 pages, 6 figures
Published: 2014
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25. Study of the $\vec{p}d \to n\{pp\}_{s}$ charge-exchange reaction using a polarised deuterium target

Author: Gou, B., Mchedlishvili, D., Bagdasarian, Z., Barsov, S., Chiladze, D., Dymov, S., Engels, R., Gaisser, M., Gebel, R., Grigoryev, K., Hartmann, M., Kacharava, A., Khoukaz, A., Kulessa, P., Kulikov, A., Lehrach, A., Li, Z., Lomidze, N., Lorentz, B., Macharashvili, G., Merzliakov, S., Mielke, M., Mikirtychyants, M., Mikirtychyants, S., Nioradze, M., Ohm, H., Prasuhn, D., Rathmann, F., Serdyuk, V., Seyfarth, H., Shmakova, V., Ströher, H., Tabidze, M., Trusov, S., Tsirkov, D., Uzikov, Yu., Valdau, Yu., Wang, T., Weidemann, C., Wilkin, C., and Yuan, X.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The vector and tensor analysing powers, $A_y$ and $A_{yy}$, of the $\vec{p}d \to n\{pp\}_{s}$ charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the $^{1}S_{0}$ state, here denoted by $\{pp\}_{s}$. The polarisation of the deuterium gas was established through measurements in parallel of proton-deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers $q\geq 160$ MeV/$c$. These data provide a good continuation of the earlier results at $q\leq 140$ MeV/$c$ obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings.
Published: 2014
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26. Search for a dark photon in the $��^0 \to e^+e^-��$ decay

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., Bondar, A., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. -O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Kuzmin, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Shwartz, B., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wirzba, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Zabierowski, J., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The presently world largest data sample of pi0 --> gamma e+e- decays containing nearly 5E5 events was collected using the WASA detector at COSY. A search for a dark photon U produced in the pi0 --> gamma U --> gamma e+e- decay from the pp-->pp��^0 reaction was carried out. An upper limit on the square of the U-gamma mixing strength parameter epsilon^2 of 5e-6 at 90% CL was obtained for the mass range 20 MeV, 16 pages, 8 figures; improved analysis extending the exclusion region to 20 MeV
Published: 2013
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27. Search for the eta-mesic 4He with WASA-at-COSY detector

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berlowski, M., Bhatt, H., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstroem, C. -O., Hauenstein, F., Heijkenskjoeld, L., Hejny, V., Hinterberger, F., Hodana, M., Hoeistad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Krapp, M., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Niedzwiecki, S., Ohm, H., Ozerianska, I., del Rio, E. Perez, Plucinski, P., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zielinski, M. J., Zipper, W., Zlomanczuk, J., Zupranski, P., and Zurek, M.
Subjects: FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: An exclusive measurement of the excitation function for the dd->3Heppi- reaction was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta meson production in the dd->4He-eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the 4He-eta system varied from -51.4MeV to 22MeV. The integrated luminosity in the experiment was determined using the dd->3Hen reaction. The shape of the excitation function for the dd->3Heppi- was examined. No signal of the 4He-eta bound state was observed. An upper limit for the cross-section for the bound state formation and decay in the process dd->(4He-eta)bound->3Heppi- was determined on the 90% confidence level and it varies from 20nb to 27nb for the bound state width ranging from 5MeV to 35MeV, respectively., 8 pages, 9 figures
Published: 2013
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28. Measurement of the $pn \to pp��^0��^-$ Reaction in Search for the Recently Observed Resonance Structure in $d��^0��^0$ and $d��^+��^-$ systems

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: Exclusive measurements of the quasi-free $pn \to pp��^0��^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, {\it i.e.} low-mass enhancement is found in the $��^0��^-$-invariant mass spectrum -- in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s-wave. At the upper end of the covered energy region $t$-channel processes for Roper, $��(1600)$ and $��$ excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at $m$=~2.37 GeV with $��$ =~70 MeV and $I(J^P)=~0(3^+)$ observed recently in $pn \to d��^0��^0$ and $pn \to d��^+��^-$ reactions leads to an agreement with the data also at low energies.
Published: 2013
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29. Measurement of spin observables in the quasi-free np-> {pp}_s pi- reaction at 353 MeV

Author: Dymov, S., Shmakova, V., Azaryan, T., Barsov, S., Baru, V., Benati, P., Chiladze, D., Dzyuba, A., Engels, R., Gaisser, M., Gebel, R., Grigoryev, K., Goslawski, P., Guidoboni, G., Hartmann, M., Kacharava, A., Kamerdzhiev, V., Khoukaz, A., Komarov, V., Kulessa, P., Kulikov, A., Kurbatov, V., Lehrach, A., Lenisa, P., Lensky, V., Lomidze, N., Lorentz, B., Macharashvili, G., Maier, R., Mchedlishvili, D., Merzliakov, S., Mielke, M., Mikirtychyants, M., Mikirtytchiants, S., Nioradze, M., Oellers, D., Ohm, H., Polyanskiy, A., Papenbrock, M., Prasuhn, D., Rathmann, F., Serdyuk, V., Seyfarth, H., Steffens, E., Stein, H. J., Stockhorst, H., Str��her, H., Tabidze, M., Trusov, S., Tsirkov, D., Uzikov, Yu., Valdau, Yu., Weidemann, Ch., Wilkin, C., W��stner, P., Ye, Q. J., and Zhabitsky, M.
Subjects: Nuclear Theory (nucl-th), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: The transverse spin correlations A_{x,x} and A_{y,y} have been measured in the pol{d} pol{p} -> p_spec {pp}_s pi- reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}_s denotes a proton-proton pair with low excitation energy, which is dominantly in the 1S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton p_spec so that the reaction could be interpreted in terms of quasi-free pol{n} pol{p} -> {pp}_s pi-. The proton analyzing power in this reaction was also deduced from this data set by averaging over the polarization of the deuteron beam. The values of A_y^p were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our earlier measurements of the differential cross sections and analyzing powers in the pol{p} p -> {pp}_s pi^0 reaction, a more robust partial wave decomposition was achieved. Three different acceptable solutions were found and the only way of resolving this ambiguity without further theoretical input would be through a measurement of the mixed spin-correlation parameter A_{x,z}.
Published: 2013
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30. Investigation of the dd -> 3He n ��0 reaction with the FZ J��lich WASA-at-COSY facility

Author: COSY Collaboration, Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Ber��owski, M., Bhatt, H., B��scher, M., Cal��n, H., Ciepa��, I., Clement, H., Coderre, D., Czerwi��ski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Goswami, A., Grigoryev, K., Gullstr��m, C. --O., Hanhart, C., Hauenstein, F., Heijkenskj��ld, L., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kirillov, D. A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Krapp, M., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Maria��ski, B., Mikirtychiants, M., Morsch, H. --P., Moskal, P., Nandi, B. K., Ohm, H., Ozerianska, I., del Rio, E. Perez, Piskunov, N. M., Pluci��ski, P., Podkopa��, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schmidt, A., Schadmand, S., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Stephan, E., Sterzenbach, G., Stockhorst, H., Str��her, H., Szczurek, A., Tolba, T., Trzci��ski, A., Varma, R., Wagner, G. J., W��glorz, W., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yamamoto, A., Yuan, X., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., ��upra��ski, P., and ��urek, M.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract: An exclusive measurement of the dd -> 3He n ��0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. The data are described with a phenomenological approach based on a combination of a quasi-free model and a partial wave expansion for three-body reaction. The total cross section is found to be ��(tot) = (2.89 +- 0.01(stat) +- 0.06(sys) +- 0.29(norm)) ��b. The contribution of the quasi-free processes (with the neutron being target or beam spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of the phase space. The remaining part of the cross section can be described within a partial wave decomposition indicating the significance of p-wave contributions in the final state., 9 pages, 7 figures
Published: 2013
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31. First measurements of spin correlations in the np -> d pi^0 reaction

Author: Shmakova, V., Mchedlishvili, D., Dymov, S., Azaryan, T., Barsov, S., Chiladze, D., Engels, R., Gebel, R., Gou, B., Grigoryev, K., Hartmann, M., Kacharava, A., Komarov, V., Kulessa, P., Kulikov, A., Kurbatov, V., Lomidze, N., Lorentz, B., Macharashvili, G., Merzliakov, S., Mikirtytchiants, M., Mikirtytchiants, S., Nioradze, M., Ohm, H., Prasuhn, D., Rathmann, F., Serdyuk, V., Seyfarth, H., Str��her, H., Tabidze, M., Trusov, S., Tsirkov, D., Uzikov, Yu., Valdau, Yu., and Wilkin, C.
Subjects: Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The transverse spin correlations Axx and Ayy in the np-> d pi^0 reaction have been measured for the first time in quasi-free kinematics at the COSY-ANKE facility using a polarised deuteron beam incident on a polarised hydrogen cell target. The results obtained for neutron energies close to 353 MeV and 600 MeV are in good agreement with the partial wave analysis of data on the isospin-related pp-> d pi^+ reaction, though the present results cover also the small-angle region, which was largely absent from these data.
Published: 2013
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32. ABC Resonance Structure in the Double-Pionic Fusion to 4He

Author: Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Berlowski, M., Bhatt, H., Brinkmann, K. T., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Demmich, K., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullstroem, C. O., Hauenstein, F., Heijkenskjold, L., Hejny, V., Hinterberger, F., Hodana, M., Hoistad, B., Husmann, C., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khan, F. A., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Krzemien, W., Kulessa, P., Kupsc, A., Lalwani, K., Lersch, D., Li, L., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Morsch, H. P., Moskal, P., Nandi, B. K., Niedzwiecki, S., Ohm, H., Ozerianska, I., Pauly, C., del Rio, E. Perez, Petukhov, Y., Plucinski, P., Podkopal, P., Prasuhn, D., Pricking, A., Pszczel, D., Pysz, K., Pyszniak, A., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Serdyuk, V., Shah, N., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Wkeglorz, W., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yamamoto, A., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zielinski, M. J., Zipper, W., Zlomanczuk, J., and Zupranski, P.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, High Energy Physics - Experiment
Abstract: Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction $dd \to ^4$He$\pi^0\pi^0$ have been performed in the energy range 0.8 - 1.4 GeV covering thus the region of the ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY. Similar to the observation in the basic $pn \to d \pi^0\pi^0$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. The maximum occurs at m=2.37 GeV + 2$m_N$, i.e. at the same position as in the basic reaction. The observed resonance width $\Gamma \approx$ 160 MeV can be understood from broadening due to Fermi motion of the nucleons in initial and final nuclei together with collision damping. Differential cross sections are described equally well by the hypothesis of a $pn$ resonance formation during the reaction process.
Published: 2012
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33. The Polarized H and D Atomic Beam Source for ANKE at COSY-J��lich

Author: Mikirtychyants, M., Engels, R., Grigoryev, K., Kleines, H., Kravtsov, P., Lorenz, S., Nekipelov, M., Nelyubin, V., Rathmann, F., Sarkadi, J., Schieck, H. Paetz gen., Seyfarth, H., Steffens, E., Str��her, H., and Vasilyev, A.
Subjects: Accelerator Physics (physics.acc-ph), Atomic Physics (physics.atom-ph), FOS: Physical sciences, Physics::Atomic Physics, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment (nucl-ex)
Abstract: A polarized atomic beam source was developed for the polarized internal storage-cell gas target at the magnet spectrometer ANKE of COSY-J��lich. The intensities of the beams injected into the storage cell, measured with a compression tube, are $7.5\cdot 10^{16}$ hydrogen atoms/s (two hyperfine states) and $3.9\cdot 10^{16}$ deuterium atoms/s (three hyperfine states). For the hydrogen beam the achieved vector polarizations are $p_{\rm z}\approx\pm0.92$. For the deuterium beam, the obtained combinations of vector and tensor ($p_{\rm zz}$) polarizations are $p_{\rm z}\approx\pm 0.90$ (with a constant $p_{\rm zz}\approx +0.86$), and $p_{\rm zz}=+0.90$ or $p_{\rm zz}=-1.71$ (both with vanishing $p_{\rm z}$). The paper includes a detailed technical description of the apparatus and of the investigations performed during the development., 18 pages, 26 figures, 4 tables
Published: 2012
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34. The neutron-proton charge-exchange amplitudes measured in the dp -> ppn reaction

Author: Mchedlishvili, D., Barsov, S., Carbonell, J., Chiladze, D., Dymov, S., Dzyuba, A., Engels, R., Gebel, R., Glagolev, V., Grigoryev, K., Goslawski, P., Hartmann, M., Kacharava, A., Kamerdzhiev, V., Keshelashvili, I., Khoukaz, A., Komarov, V., Kulessa, P., Kulikov, A., Lehrach, A., Lomidze, N., Lorentz, B., Macharashvili, G., Maier, R., Merzliakov, S., Mielke, M., Mikirtychyants, M., Mikirtychyants, S., Nioradze, M., Ohm, H., Papenbrock, M., Prasuhn, D., Rathmann, F., Serdyuk, V., Seyfarth, H., Stein, H. J., Steffens, E., Stockhorst, H., Stroeher, H., Tabidze, M., Trusov, S., Uzikov, Yu., Valdau, Yu., and Wilkin, C.
Subjects: Nuclear Theory (nucl-th), Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: The unpolarised differential cross section and the two deuteron tensor analysing powers A_{xx} and A_{yy} of the pol{d}p -> (pp)n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27 GeV, data were obtained for small momentum transfers to a (pp) system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C_{x,x} and C_{y,y} that were carried out in the pol{d}pol{p} -> (pp)n reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region., 13 pages with 13 figures
Published: 2012
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35. ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?

Author: Adlarson, P., Adolph, C., Augustyniak, W., Baru, V., Bashkanov, M., Bergmann, F. S., Berlowski, M., Bhatt, H., Brinkmann, K. -T., Buescher, M., Calen, H., Clement, H., Coderre, D., Czerwinski, E., Doroshkevich, E., Ekstrom, C., Engels, R., Erven, W., Eyrich, W., Fedorets, P., Foehl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Grishina, V., Gullstrom, C. -O., Hampe, J., Hanhart, C., Heijkenskj, L., Hejny, V., Hinterberger, F., Hodana, M., Hoistad, B., Jacewicz, M., Janusz, M., Jany, A., Jany, B. R., Jarczyk, L., Jaus, J., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., Klos, B., Kren, F., Krzemien, W., Kulessa, P., Kullander, S., Kupsc, A., Lalwani, K., Lorentz, B., Magiera, A., Maier, R., Marciniewski, P., Marianski, B., Mikirtychiants, M., Moskal, P., Morsch, H. -P., Nandi, B. K., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petukhov, Y., Piskunov, N., Plucinski, P., Podkopal, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Ruber, R. J. M. Y., Rudy, Z., Schadmand, S., Schmidt, A., Schroeder, W., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stroeher, H., Szczurek, A., Taeschner, A., Tolba, T., Trzcinski, A., Varma, R., Vlasov, P., Wagner, G. J., Weglorz, W., Winnemoeller, A., Wirzba, A., Wolke, M., Wronska, A., Wuestner, P., Wurm, P., Yurev, L., Zabierowski, J., Zielinski, M. J., Zipper, W., Zlomanczuk, J., and Zupranski, P.
Subjects: FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: We report on a high-statistics measurement of the basic double pionic fusion reaction $pn \to d\pi^0\pi^0$ over the energy region of the so-called ABC effect, a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The measurements were performed with the WASA detector setup at COSY. The data reveal the ABC effect to be associated with a Lorentzian shaped energy dependence in the integral cross section. The observables are consistent with a resonance with $I(J^P) =0(3^+)$ in both $pn$ and $\Delta\Delta$ systems. Necessary further tests of the resonance interpretation are discussed.
Published: 2011

36. Exclusive Measurement of the eta --> pi+ pi- gamma Decay

Author: Adlarson, P., Adolph, C., Augustyniak, W., Bardan, W., Bashkanov, M., Bednarski, T., Bergmann, F. S., Ber��owski, M., Bhatt, H., Brinkmann, K. -T., B��scher, M., Cal��n, H., Clement, H., Coderre, D., Czerwi��ski, E., Doroshkevich, E., Engels, R., Erven, W., Eyrich, W., Fedorets, P., F��hl, K., Fransson, K., Goldenbaum, F., Goslawski, P., Grigoryev, K., Gullstr��m, C. -O., Hanhart, C., Heijkenskj��ld, L., Heimlich, J., Hejny, V., Hinterberger, F., Hodana, M., H��istad, B., Jacewicz, M., Jany, A., Jany, B. R., Jarczyk, L., Johansson, T., Kamys, B., Kemmerling, G., Khakimova, O., Khoukaz, A., Kistryn, S., Klaja, J., Kleines, H., K��os, B., Kren, F., Krzemie��, W., Kulessa, P., Kup��, A., Lalwani, K., Leupold, S., Lorentz, B., Magiera, A., Maier, R., Maria��ski, B., Marciniewski, P., Mei��ner, U. -G., Mikirtychiants, M., Morsch, H. -P., Moskal, P., Nandi, B. K., Nied��wiecki, S., Ohm, H., Passfeld, A., Pauly, C., del Rio, E. Perez, Petri, T., Petukhov, Y., Piskunov, N., Pluci��ski, P., Podkopa��, P., Povtoreyko, A., Prasuhn, D., Pricking, A., Pysz, K., Pyszniak, A., Rausmann, T., Redmer, C. F., Ritman, J., Roy, A., Rudy, Z., Sawant, S., Schadmand, S., Schmidt, A., Sefzick, T., Serdyuk, V., Shah, N., Siemaszko, M., Siudak, R., Skorodko, T., Skurzok, M., Smyrski, J., Sopov, V., Stassen, R., Stepaniak, J., Sterzenbach, G., Stockhorst, H., Stollenwerk, F., Szczurek, A., T��schner, A., Terschl��sen, C., Tolba, T., Trzci��ski, A., Varma, R., Vlasov, P., Wagner, G. J., W��glorz, W., Winnem��ller, A., Wirzba, A., Wolke, M., Wro��ska, A., W��stner, P., Wurm, P., Yuan, X., Yurev, L., Zabierowski, J., Zheng, C., Zieli��ski, M. J., Zipper, W., Z��oma��czuk, J., and ��upra��ski, P.
Subjects: High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: An exclusive measurement of the decay eta --> pi+ pi- gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd --> 3He X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13340\pm140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta --> pi+ pi- gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi+ pi- system., 7 pages, 10 figures, submitted to Phys.Lett.B
Published: 2011
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37. Measurement of the Spin-Dependence of the pbar-p Interaction at the AD-Ring

Author: Barschel, C., Bechstedt, U., Dietrich, J., Dolfus, N., Engels, R., Gebel, R., Hadamek, H., Haidenbauer, J., Hanhart, C., Kacharava, A., Krol, G., Kueven, M., Langenberg, G., Lehrach, A., Lorentz, B., Maier, R., Martin, S., Meissner, U.-G., Nekipelov, M., Nikolaev, N. N., Oellers, D., D'Orsaneo, G., Prasuhn, D., Rathmann, F., Retzlaff, M., Sarkadi, J., Schleichert, R., Seyfarth, H., Sibirtsev, A., Spoelgen, D., Stein, H. J., Stockhorst, H., Stroeher, H., Weidemann, C., Welsch, D., Wieder, P., Barion, L., Bertelli, S., Carassiti, V., Ciullo, G., Contalbrigo, M., Cotta-Ramusino, A., Dalpiaz, P. F., Drago, A., Guidoboni, G., Lenisa, P., Pappalardo, L., Stancari, G., Stancari, M., Statera, M., Azarian, T., Kulikov, A., Kurbatov, V., Macharashvili, G., Merzliakov, S., Meshkov, I. N., Smirnov, A., Tsirkov, D., Uzikov, Y., Barsov, S., Belostotski, S., Grigoryev, K., Kravtsov, P., Mikirtychiants, M., Mikirtychiants, S., Vasilyev, A., Esser, F. M., Greven, R., Hansen, G., Jadgfeld, F., Klehr, F., Soltner, H., Straatmann, H., Chiladze, D., Garishvili, A., Lomidze, N., Mchedlishvili, D., Nioradze, M., Tabidze, M., Akopov, N., Avetisyan, A., Elbakyan, G., Marukyan, H., Taroian, S., Benati, P., Erven, W., Kayser, F. J., Kleines, H., Wuestner, P., Bruncko, D., Ferencei, J., Musinsky, J., Urban, J., Augustyniak, W., Marianski, B., Trzcinski, A., Zupranski, P., Dymov, S., Nass, A., Steffens, E., Rathsman, K., Tegner, P. E., Thoerngren Engblom, P., Leo, R., Tagliente, G., Kaempfer, B., Trusov, S., Buttimore, N., and Meyer, H. O.
Subjects: FOS: Physical sciences, Physics::Accelerator Physics, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: We propose to use an internal polarized hydrogen storage cell gas target in the AD ring to determine for the first time the two total spin-dependent pbar-p cross sections sigma_1 and sigma_2 at antiproton beam energies in the range from 50 to 450 MeV. The data obtained are of interest by themselves for the general theory of pbar-p interactions since they will provide a first experimental constraint of the spin-spin dependence of the nucleon-antinucleon potential in the energy range of interest. In addition, measurements of the polarization buildup of stored antiprotons are required to define the optimum parameters of a future, dedicated Antiproton Polarizer Ring (APR), intended to feed a double-polarized asymmetric pbar-p collider with polarized antiprotons. Such a machine has recently been proposed by the PAX collaboration for the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany. The availability of an intense stored beam of polarized antiprotons will provide access to a wealth of single- and double-spin observables, thereby opening a new window on QCD spin physics., 51 pages, 23 figures, proposal submitted to the SPS committee of CERN
Published: 2009

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