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24. Study of the quasi-free $np \to np \pi^+\pi^-$ reaction with a deuterium beam at 1.25 GeV/nucleon

Author

Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Göbel, K., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Vasiliev, T., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

The tagged quasi-free $np \to np\pi^+\pi^-$ reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon ($\sqrt s \sim$ 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions for $\pi^{+}\pi^{-}$ production in $np$ collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the $np\rightarrow np\pi^{+}\pi^{-}$ reaction are compared with different models. This comparison confirms the dominance of the $t$-channel with $\Delta\Delta$ contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the $\pi^{+}\pi^{-}$ invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M$\sim$ 2.38 GeV and with width $\Gamma\sim$ 70 MeV.

Published
2015
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25. Influence of co-sputtering AlB2 to TaB2 on stoichiometry of non-reactively sputtered boride thin films.

Author

Hu, Chun, Lin, Shuyao, Podsednik, M., Mráz, Stanislav, Wojcik, T., Limbeck, A., Koutná, Nikola, and Mayrhofer, Paul H.

Subjects
THIN films, MECHANICAL behavior of materials, EVAPORATIVE power, ANGULAR distribution (Nuclear physics), BORIDES, ELASTIC modulus, EVAPORATION (Chemistry), STOICHIOMETRY
Abstract

Transition metal diboride thin films are promising functional materials for their outstanding mechanical properties and thermal stability. By combining experiment and simulations, we discuss angular distribution of the sputtered species, their scattering in the gas phase, re-sputtering and potential evaporation from the grown films for the complex evolution of film compositions, as well as energetic preference for vacancy formation and competing phases as factors for governing the phase constitution. By co-sputtering from two compound targets, we developed phase-pure crystalline (Ta,Al)B2 solid solution thin films and correlate the stoichiometry changes with the evolution of their microstructure, hardness, and elastic modulus. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Influence of co-sputtering AlB2 to TaB2 on stoichiometry of non-reactively sputtered boride thin films

Author

Hu, Chun, Lin, Shuyao, Podsednik, M., Mraz, Stanislav, Wojcik, T., Limbeck, A., Koutna, Nikola, Mayrhofer, Paul H., Hu, Chun, Lin, Shuyao, Podsednik, M., Mraz, Stanislav, Wojcik, T., Limbeck, A., Koutna, Nikola, and Mayrhofer, Paul H.

Abstract

Transition metal diboride thin films are promising functional materials for their outstanding mechanical properties and thermal stability. By combining experiment and simulations, we discuss angular distribution of the sputtered species, their scattering in the gas phase, re-sputtering and potential evaporation from the grown films for the complex evolution of film compositions, as well as energetic preference for vacancy formation and competing phases as factors for governing the phase constitution. By co-sputtering from two compound targets, we developed phase-pure crystalline (Ta,Al)B2 solid solution thin films and correlate the stoichiometry changes with the evolution of their microstructure, hardness, and elastic modulus. {GRAPHICAL ABSTRACT}, Funding Agencies|Christian Doppler Laboratory for Surface Engineering of High-Performance Components, TU Wien, Austria

Published
2024
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34. Inclusive dielectron production in proton-proton collisions at 2.2 GeV beam energy

Author

Agakishiev, G., Alvarez-Pol, H., Balanda, A., Bassini, R., Böhmer, M., Bokemeye, H., Boyard, J. L., Cabanelas, P., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Finocchiaro, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krizek, F., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lapidus, K., Liu, T., Maier, L., Markert, J., Metag, V., Michalska, B., Morinière, E., Mousa, J., Münch, M., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Pietraszko, J., Pospisil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sánchez, M., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Data on inclusive dielectron production are presented for the reaction p+p at 2.2 GeV measured with the High Acceptance DiElectron Spectrometer (HADES). Our results supplement data obtained earlier in this bombarding energy regime by DLS and HADES. The comparison with the 2.09 GeV DLS data is discussed. The reconstructed e+e- distributions are confronted with simulated pair cocktails, revealing an excess yield at invariant masses around 0.5 GeV/c2. Inclusive cross sections of neutral pion and eta production are obtained.

Published
2012
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35. Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

Author

HADES Collaboration, Agakishiev, G., Alvarez-Pol, H., Balanda, A., Bassini, R., Böhmer, M., Bokemeyer, H., Boyard, J. L., Cabanelas, P., Chernenko, S., Christ, T., Destefanis, M., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Finocchiaro, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Gumberidze, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krizek, F., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lapidus, K., Liu, T., Maier, L., Markert, J., Metag, V., Michalska, B., Morinière, E., Mousa, J., Münch, M., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Pechenov, V., Pechenova, O., Cavalcanti, T. Pérez, Pietraszko, J., Pospísil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sánchez, M., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

We present measurements of exclusive \pi^{+,0} and \eta\ production in pp reactions at 1.25 GeV and 2.2 GeV beam kinetic energy in hadron and dielectron channels. In the case of \pi^+ and \pi^0, high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of \Delta(1232) and higher lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross sections are of special interest in the case of pp \to pp \eta, since controversial data exist at 2.0 GeV; we find \sigma =0.142 \pm 0.022 mb. Using the dielectron channels, the \pi^0 and \eta\ Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance corrected helicity angle distributions are found in good agreement with model predictions., Comment: 22 pages, 18 figures, to be published in EPJA

Published
2012
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36. Hyperon production in Ar+KCl collisions at 1.76A GeV

Author

Agakishiev, G., Balanda, A., Bannier, B., Bassini, R., Belver, D., Belyaev, A., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Epple, E., Fabbietti, L., Fateev, O., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Gumberidze, M., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Huck, P., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Perez-Cavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Siebenson, J., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., Zumbruch, P., and Collaboration, HADES

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

We present transverse momentum spectra, rapidity distribution and multiplicity of Lambda-hyperons measured with the HADES spectrometer in the reaction Ar(1.76A GeV)+KCl. The yield of Xi- is calculated from our previously reported Xi-/(Lambda+Sigma0) ratio and compared to other strange particle multiplicities. Employing a strangeness balance equation the multiplicities of the yet unmeasured charged Sigma hyperons can be estimated. Finally a statistical hadronization model is used to fit the yields of pi-, K+, K0s, K-, phi, Lambda and Xi-. The resulting chemical freeze-out temperature of T=(76+-2) MeV is compared to the measured slope parameters obtained from fits to the transverse mass distributions of the particles.

Published
2010
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37. In-Medium Effects on K0 Mesons in Relativistic Heavy-Ion Collisions

Author

Agakishiev, G., Balanda, A., Bannier, B., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Epple, E., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., PérezCavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebac, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfel, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

We present the transverse momentum spectra and rapidity distributions of $\pi^{-}$ and K$^0_S$ in Ar+KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the spectrometer HADES. The reconstructed K$^0_S$ sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental $\pi^{-}$ and K$^0_S$ distributions to predictions by the IQMD model. The model calculations show that K$^0_S$ at low tranverse momenta constitute a particularly well suited tool to investigate the kaon in-medium potential. Our K$^0_S$ data suggest a strong repulsive in-medium K$^0$ potential of about 40 MeV strength., Comment: 10 pages, 10 figures, accepted by Phys. Rev. C

Published
2010
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38. Lambda-p femtoscopy in collisions of Ar+KCl at 1.76 AGeV

Author

Agakishiev, G., Balanda, A., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wendisch, C., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Results on $\Lambda$p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76A~GeV, the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of $\Lambda$ p correlations at small relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the $\Lambda$p emission source. The $\Lambda$p source radius is found slightly smaller than the pp correlation radius for a similar collis ion system. The present $\Lambda$p radius is significantly smaller than that found for Au+Au/Pb+Pb collisio ns in the AGS, SPS and RHIC energy domains, but larger than that observed for electroproduction from He. Taking into account all available data, we find the $\Lambda$p source radius to increase almost linearly with the number of participants to the power of one-third., Comment: 5 pages, 3 figures, submitted to Phys. Rev. C

Published
2010
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39. Recent results from HADES on electron pair production in relativistic heavy-ion collisions

Author

The HADES Collaboration, Galatyuk, T., Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

Systematic investigations of dilepton production are performed at the SIS accelerator of GSI with the HADES spectrometer. The goal of this program is a detailed understanding of di-electron emission from hadronic systems at moderate temperatures and densities. New results obtained in HADES experiments focussing on electron pair production in elementary collisions are reported here. They pave the way to a better understanding of the origin of the so-called excess pairs earlier on observed in heavy-ion collisions by the DLS collaboration and lately confirmed in two measurements of the HADES collaboration using C+C and Ar+KCl collisions. Results of these studies are discussed., Comment: 8 pages, 5 figures, To appear in the proceedings of 5th International Workshop on Critical Point and Onset of Deconfinement (CPOD), Brookhaven, Upton, New York, 8-12 Jun 2009

Published
2009

40. Origin of the low-mass electron pair excess in light nucleus-nucleus collisions

Author

The HADES Collaboration, Agakishiev, G., Balanda, A., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Rustamov, A., Sadovsky, A., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems., Comment: 11 pages, 2 figures, \usepackage{epsfig}

Published
2009
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41. Deep sub-threshold $\Xi^-$ production in Ar+KCl reactions at 1.76A GeV

Author

Agakishiev, G., Balanda, A., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Böhmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Díaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Gil, A., Gilardi, C., Golubeva, M., González-Díaz, D., Guber, F., Hennino, T., Holzmann, R., Iori, I., Ivashkin, A., Jurkovic, M., Kämpfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Krücken, R., Kühn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Morinière, E., Mousa, J., Müntz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Sobolev, Yu. G., Spataro, S., Spruck, B., Ströbele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wüstenfeld, J., Yurevich, S., Zanevsky, Y. V., and Zhou, P.

Subjects
Nuclear Experiment
Abstract

We report first results on a deep sub-threshold production of the doubly strange hyperon $\Xi^-$ in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of the decay channel $\Xi^- \to \Lambda \pi^-$. The deduced $\Xi^-/(\Lambda+\Sigma^0)$ production ratio of $(5.6 \pm 1.2 ^{+1.8}_{-1.7})\cdot 10^{-3}$ is significantly larger than available model predictions., Comment: 4 pages, including 4 figures

Published
2009
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42. Measurement of charged pions in 12C + 12C collisions at 1A GeV and 2A GeV with HADES

Author

The HADES Collaboration, Agakishiev, G., Agodi, C., Balanda, A., Bellia, G., Belver, D., Belyaev, A., Bielcik, J., Blanco, A., Bortolotti, A., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Chernenko, S., Christ, T., Coniglione, R., Destefanis, M., Diaz, J., Dohrmann, F., Duran, I., Dybczak, A., Eberl, T., Fabbietti, L., Fateev, O., Ferreira-Marques, R., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Grosse, E., Guber, F., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lamas-Valverde, J., Lang, S., Lange, J. S., Lapidus, K., Lopes, L., Lorenz, M., Maier, L., Maiolino, C., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Michel, J., Moriniere, E., Mousa, J., Muench, M., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Cavalcanti, T. Perez, Piattelli, P., Pietraszko, J., Pospisil, V., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Sapienza, P., Schmah, A., Schroeder, C., Schwab, E., Simon, R. S., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebacz, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

We present the results of a study of charged pion production in 12C + 12C collisions at incident beam energies of 1A GeV and 2A GeV using the HADES spectrometer at GSI. The main emphasis of the HADES program is on the dielectron signal from the early phase of the collision. Here, however, we discuss the data with respect to the emission of charged hadrons, specifically the production of pi+- mesons, which are related to neutral pions representing a dominant contribution to the dielectron yield. We have performed the first large-angular range measurement of the distribution of pi+- mesons for the 12C + 12C collision system covering a fairly large rapidity interval. The pion yields, transverse-mass and angular distributions are compared with calculations done within a transport model, as well as with existing data from other experiments. The anisotropy of pion production is systematically analyzed., Comment: 15 pages, 13 figures, v2 - the text unchanged, only full author list added to METADATA (in v1 only the first author and collaboration name), reference to published paper added

Published
2009
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43. The High-Acceptance Dielectron Spectrometer HADES

Author

The HADES Collaboration, Agakishiev, G., Balanda, A., Bannier, B., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Boehmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Enghardt, W., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., PerezCavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebac, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wuestenfel, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion induced collisions. Its main features include a ring imaging gas Cherenkov detector for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from 18 to 85 degree, a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range. This paper describes the main features and the performance of the detector system.

Published
2009
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44. Phi decay: a relevant source for K- production at SIS energies?

Author

The HADES Collaboration, Agakishiev, G., Balanda, A., Bannier, B., Bassini, R., Belver, D., Belyaev, A. V., Blanco, A., Boehmer, M., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Chernenko, S., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Enghardt, W., Fabbietti, L., Fateev, O. V., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil1, A., Gilardi, C., Golubeva, M., Gonzalez-Diaz, D., Guber, F., Heilmann, M., Heinz, T., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Lang, S., Lange, J. S., Lapidus, K., Liu, T., Lopes, L., Lorenz, M., Maier, L., Mangiarotti, A., Markert, J., Metag, V., Michalska, B., Michel, J., Mishra, D., Moriniere, E., Mousa, J., Muentz, C., Naumann, L., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., PerezCavalcanti, T., Pietraszko, J., Przygoda, W., Ramstein, B., Reshetin, A., Roy-Stephan, M., Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Schwab, E., Sobolev, Yu. G., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Traxler, M., Trebac, R., Tsertos, H., Wagner, V., Weber, M., Wisniowski, M., Wojcik, T., Wuestenfel, J., Yurevich, S., Zanevsky, Y. V., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

We present phase space distributions and multiplicities of K+, K- and phi mesons produced in Ar+KCl reactions at a kinetic beam energy of 1.756 AGeV and measured with the HADES spectrometer. The inverse slope parameters and yields of kaons supplement the systematics of previous measurements. The percentage of K- mesons coming fromphi decay is found to be 18+- 7%.

Published
2009
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47. Study of dielectron production in C+C collisions at 1 AGeV

Author

HADES Collaboration, Agakishiev, G., Agodi, C., Pol, H. Alvarez, Balanda, A., Bassini, R., Bellia, G., Belver, D., Belyaev, A., Blanco, A., Boehmer, M., Bortolotti, A., Boyard, J. L., Braun-Munzinger, P., Cabanelas, P., Castro, E., Christ, T., Destefanis, M., Diaz, J., Dohrmann, F., Dybczak, A., Eberl, T., Fabbietti, L., Finocchiaro, P., Fonte, P., Friese, J., Froehlich, I., Galatyuk, T., Garzon, J. A., Gernhaeuser, R., Gil, A., Gilardi, C., Golubeva, M., Diaz, D. Gonzalez, Grosse, E., Guber, F., Heilmann, M., Hennino, T., Holzmann, R., Ierusalimov, A., Iori, I., Ivashkin, A., Jurkovic, M., Kaempfer, B., Kanaki, K., Karavicheva, T., Kirschner, D., Koenig, I., Koenig, W., Kolb, B. W., Kotte, R., Kozuch, A., Krasa, A., Krizek, F., Kruecken, R., Kuehn, W., Kugler, A., Kurepin, A., Valverde, J. Lamas, Lang, S., Lange, J. S., Lapidus, K., Lopes, L., Maier, L., Mangiarotti, A., Marin, J., Markert, J., Metag, V., Michalska, B., Mishra, D., Moriniere, E., Mousa, J., Muench, M., Muentz, C., Naumann, L., Novotny, R., Otwinowski, J., Pachmayer, Y. C., Palka, M., Parpottas, Y., Pechenov, V., Pechenova, O., Perez, T., Pietraszko, J., Pleskac, R., Przygoda, W., Ramstein, B., Reshetin, A., Stephan, M. Roy, Rustamov, A., Sadovsky, A., Sailer, B., Salabura, P., Schmah, A., Simon, R., Sobolev, Y., Spataro, S., Spruck, B., Stroebele, H., Stroth, J., Sturm, C., Sudol, M., Tarantola, A., Teilab, K., Tlusty, P., Toia, A., Traxler, M., Trebacz, R., Tsertos, H., Veretenkin, I., Wagner, V., Weber, M., Wen, H., Wisniowski, M., Wojcik, T., Wuestenfeld, J., Yurevich, S., Zanevsky, Y., Zhou, P., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

The emission of e+e- pairs from C+C collisions at an incident energy of 1 GeV per nucleon has been investigated. The measured production probabilities, spanning from the pi0-Dalitz to the rho/omega! invariant-mass region, display a strong excess above the cocktail of standard hadronic sources. The bombarding-energy dependence of this excess is found to scale like pion production, rather than like eta production. The data are in good agreement with results obtained in the former DLS experiment., Comment: submitted to Physics Letters B

Published
2007
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