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1. The \pi^+\pi^- Coulomb interaction study and its use in the data processing

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract

In this work the Coulomb effects (Coulomb correlations) in $\pi^+\pi^-$ pairs produced in p + Ni collisions at 24 GeV/$c$, are studied using experimental $\pi^+\pi^-$ pair distributions in $Q$, the relative momentum in the pair center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) and $Q_t$ (transverse component) relative to the pair direction in the laboratory system (l.s.). The $Q$, $Q_L$, and $Q_t$ distributions of the {\sl Coulomb pairs} in the c.m.s. have been simulated assuming they are described by the phase space modified by the known point-like Coulomb correlation function $A_C(Q)$, corrected for small effects due to the nonpoint-like pair production and the strong two-pion interaction. The same distributions of {\sl non-Coulomb pairs} have been simulated according to the phase space, but without $A_C(Q)$. It is shown that the number of {\sl Coulomb pairs} in all $Q_t$ intervals, including the small $Q_t$ (small opening angles $\theta$ in the l.s.) is calculated with the theoretical precision better than 2\%. The comparison of the simulated and experimental numbers of {\sl Coulomb pairs} at small $Q_t$ allows us to check and correct the detection efficiency for the pairs with small $\theta$ (0.06 mrad and smaller). It is shown that {\sl Coulomb pairs} can be used as a new physical tool to check and correct the quality of the simulated events. The special property of the {\sl Coulomb pairs} is the possibility of checking and correcting the detection efficiency, especially for the pairs with small opening angles.

Published
2024

2. Investigation of $K^+K^-$ pairs in the effective mass region near $2m_K$

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

The DIRAC experiment at CERN investigated in the reaction $\rm{p}(24~\rm{GeV}/c) + Ni$ the particle pairs $K^+K^-, \pi^+ \pi^-$ and $p \bar{p}$ with relative momentum $Q$ in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of $K^+K^-$ pairs, obtained by subtracting -- using time-of-flight (TOF) technique -- background from initial $Q$ distributions with $K^+K^-$ sample fractions more than 70\%, 50\% and 30\%. The corresponding pair distributions in $Q$ and in its longitudinal projection $Q_L$ were analyzed first in a Coulomb model, which takes into account only Coulomb final state interaction (FSI) and assuming point-like pair production. This Coulomb model analysis leads to a $K^+K^-$ yield increase of about four at $Q_L=0.5$ MeV/c compared to 100 MeV/c. In order to study contributions from strong interaction, a second more sophisticated model was applied, considering besides Coulomb FSI also strong FSI via the resonances $f_0(980)$ and $a_0(980)$ and a variable distance $r^*$ between the produced $K$ mesons. This analysis was based on three different parameter sets for the pair production. For the 70\% subsample and with best parameters, $3680\pm 370$ $K^+K^-$ pairs was found to be compared to $3900\pm 410$ $K^+K^-$ extracted by means of the Coulomb model. Knowing the efficiency of the TOF cut for background suppression, the total number of detected $K^+K^-$ pairs was evaluated to be around $40000\pm 10\%$, which agrees with the result from the 30\% subsample. The $K^+K^-$ pair number in the 50\% subsample differs from the two other values by about three standard deviations, confirming -- as discussed in the paper -- that experimental data in this subsample is less reliable.

Published
2022
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3. First measurement of a long-lived $\pi^+ \pi^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogen-like $\pi^+\pi^-$ atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96~mm and got broken up in the 2.1~\textmu{}m thick platinum foil. Analysing the observed number of atomic pairs, $n_A^L= \left.436^{+157}_{-61}\right|_\mathrm{tot}$, the lifetime of the 2$p$ state is found to be ${\tau_{2p}=(\left.0.45^{+1.08}_{-0.30}\right|_\mathrm{tot}) \cdot10^{-11}}$s, not contradicting the corresponding QED $2p$ state lifetime ${\tau_{2p}^\mathrm{QED}=1.17 \cdot 10^{-11}}$s. This lifetime value is three orders of magnitude larger than our previously measured value of the $\pi^+\pi^-$ atom ground state lifetime $\tau=(\left.3.15^{+0.28}_{-0.26}\right|_\mathrm{tot})\cdot 10^{-15}$s. Further studies of long-lived $\pi^+\pi^-$ atoms will allow to measure energy differences between $p$ and $s$ atomic states and so to determine $\pi\pi$ scattering lengths with the aim to check QCD predictions., Comment: 7 pages, 8 figures

Published
2018
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4. Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length

Author

DIRAC Collaboration, Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

After having announced the statistically significant observation (5.6~$\sigma$) of the new exotic $\pi K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $\pi K$ data sample: $\tau = (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means of a precise relation ($<1\%$) between atom lifetime and scattering length, the following value for the S-wave isospin-odd $\pi K$ scattering length $a_0^{-}~=~\frac{1}{3}(a_{1/2}-a_{3/2})$ has been derived: $\left|a_0^-\right| = (0.072^{+0.031}_{-0.020}) M_{\pi}^{-1}$., Comment: 18 pages, 17 figures

Published
2017
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5. First $\pi K$ atom lifetime and $\pi K$ scattering length measurements

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Ponta, T., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The results of a search for hydrogen-like atoms consisting of $\pi^{\mp}K^{\pm}$ mesons are presented. Evidence for $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $\pi K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using these results the analysis yields a first value for the $\pi K$ atom lifetime of $\tau=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $\pi K$ scattering length $\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|= \left(0.11_{-0.04}^{+0.09} \right)M_{\pi}^{-1}$ ($a_I$ for isospin $I$)., Comment: 14 pages, 8 figures

Published
2014
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6. Determination of $\pi\pi$ scattering lengths from measurement of $\pi^+\pi^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P. V., Ciocarlan, C., Constantinescu, S., Costantini, S., Curceanu, C., Doskarova, P., Dreossi, D., Drijard, D., Dudarev, A., Ferro-Luzzi, M., Pazos, J. L. Fungueiriño, Torreira, M. Gallas, Gerndt, J., Gianotti, P., Goldin, D., Gomez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kuroda, K. I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Sandri, P. Levi, Aguera, A. Lopez, Lucherini, V., Maki, T., Manuilov, I., Marin, J., Narjoux, J. L., Nemenov, L., Nikitin, M., Pardo, T. Nunez, Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J. M., Plo, M., Ponta, T., Rappazzo, G. F., Riazantsev, A., Rodriguez, J. M., Fernandez, A. Rodriguez, Vidal, A. Romero, Ronjin, V. M., Rykalin, V., Saborido, J., Santamarina, C., Schacher, J., Schuetz, C., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M. J., Trojek, T., Trusov, S., Utkin, V., Doce, O. Vázquez, Vlachos, S., Voskresenskaya, O., Vrba, T., Willmott, C., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

The DIRAC experiment at CERN has achieved a sizeable production of $\pi^+\pi^-$ atoms and has significantly improved the precision on its lifetime determination. From a sample of 21227 atomic pairs, a 4% measurement of the S-wave $\pi\pi$ scattering length difference $|a_0-a_2| = (.0.2533^{+0.0080}_{-0.0078}|_\mathrm{stat}.{}^{+0.0078}_{-0.0073}|_\mathrm{syst})M_{\pi^+}^{-1}$ has been attained, providing an important test of Chiral Perturbation Theory., Comment: 6 pages, 6 figures

Published
2011
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7. Evidence for $\pi K$-atoms with DIRAC

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Benelli, A., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Curceanu, C., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fungueiriño, J. L., Gerndt, J., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Sandri, P. Levi, Aguera, A. Lopez, Lucherini, V., Manuilov, I., Mariñas, C., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Pló, M., Rappazzo, G. F., Regenfus, C., Rochet, J., Romero, A., Ronjin, V., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tarasov, A., Tauscher, L., Trojek, T., Trusov, S., Utkin, V., Doce, O. Vázquez, Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment
Abstract

We present evidence for the first observation of electromagnetically bound $\pi^\pm K^\mp$-pairs ($\pi K$-atoms) with the DIRAC experiment at the CERN-PS. The $\pi K$-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the $\pi^\pm$ and $K^\mp$-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 $\pm$ 54 $\pi K$-atoms. The mean life of $\pi K$-atoms is related to the s-wave $\pi K$-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level., Comment: 15 pages, 9 figures

Published
2009
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8. Conditional Expressions for Blind Deconvolution: Derivative form

Author

Aogaki, S., Moritani, I., Sugai, T., Takeutchi, F., and Toyama, F. M.

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

We developed novel conditional expressions (CEs) for Lane and Bates' blind deconvolution. The CEs are given in term of the derivatives of the zero-values of the z-transform of given images. The CEs make it possible to automatically detect multiple blur convolved in the given images all at once without performing any analysis of the zero-sheets of the given images. We illustrate the multiple blur-detection by the CEs for a model image, Comment: 5 page, 3 figures, conference

Published
2006

9. Simple method to eliminate blur based on Lane and Bates algorithm

Author

Aogaki, S., Moritani, I., Sugai, T., Takeutchi, F., and Toyama, F. M.

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

A simple search method for finding a blur convolved in a given image is presented. The method can be easily extended to a large blur. The method has been experimentally tested with a model blurred image., Comment: 3 pages, 2 figures, conference

Published
2006

10. Conditional Expressions for Blind Deconvolution: Multi-point form

Author

Aogaki, S., Moritani, I., Sugai, T., Takeutchi, F., and Toyama, F. M.

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

We present conditional expression (CE) for finding blurs convolved in given images. The CE is given in terms of the zero-values of the blurs evaluated at multi-point. The CE can detect multiple blur all at once. We illustrate the multiple blur-detection by using a test image., Comment: 4 pages, 3 figures, conference

Published
2006

11. Measurement of the Xi-p Scattering Cross Sections at Low Energy

Author

Ahn, J. K., Aoki, S., Chung, K. S., Chung, M. S., Enyo, H., Fukuda, T., Funahashi, H., Goto, Y., Higashi, A., Ieiri, M., Iijima, T., Iinuma, M., Imai, K., Itow, Y., Lee, J. M., Makino, S., Masaike, A., Matsuda, Y., Matsuyama, Y., Mihara, S., Nagoshi, C., Nomura, I., Park, I. S., Saito, N., Sekimoto, M., Shin, Y. M., Sim, K. S., Susukita, R., Takashima, R., Takeutchi, F., Tlusty, P., Weibe, S., Yakkaichi, S., Yoshida, K., Yoshida, M., Yoshida, T., and Yamashita, S.

Subjects
Nuclear Experiment
Abstract

In this paper we report cross-section measurements for $\Xi^-p$ elastic and inelastic scatterings at low energy using a scintillating fiber active target. Upper limit on the total cross-section for the elastic scattering was found to be 24 mb at 90% confidence level, and the total cross section for the $\Xi^-p\to\Lambda\Lambda$ reaction was found to be $4.3^{+6.3}_{-2.7}$ mb. We compare the results with currently competing theoretical estimates., Comment: 9 pages

Published
2005
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12. The multilevel trigger system of the DIRAC experiment

Author

Afanasyev, L., Gallas, M., Goldin, D., Gorin, A., Karpukhin, V., Kokkas, P., Kulikov, A., Kuroda, K., Manuilov, I., Okada, K., Schuetz, C., Sidorov, A., Steinacher, M., Takeutchi, F., Tauscher, L., Vlachos, S., and Yazkov, V.

Subjects
High Energy Physics - Experiment
Abstract

The multilevel trigger system of the DIRAC experiment at CERN is presented. It includes a fast first level trigger as well as various trigger processors to select events with a pair of pions having a low relative momentum typical of the physical process under study. One of these processors employs the drift chamber data, another one is based on a neural network algorithm and the others use various hit-map detector correlations. Two versions of the trigger system used at different stages of the experiment are described. The complete system reduces the event rate by a factor of 1000, with efficiency $\geq$95% of detecting the events in the relative momentum range of interest., Comment: 21 pages, 11 figures

Published
2002
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13. Evidence of Xi hypernuclear production in the ^{12}C(K^-,K^+)^{12}_{Xi}Be reaction

Author

Khaustov, P., Alburger, D. E., Barnes, P. D., Bassalleck, B., Berdoz, A. R., Biglan, A., Buerger, T., Carman, D. S., Chrien, R. E., Davis, C. A., Fischer, H., Franklin, G. B., Franz, J., Gan, L., Ichikawa, A., IijIma, T., Imai, K., Kondo, Y., Koran, P., Landry, M., Lee, L., Lowe, J., Magahiz, R., May, M., McCrady, R., Meyer, C. A., Merrill, F., Motoba, T., Page, S. A., Paschke, K., Pile, P. H., Quinn, B., Ramsay, W. D., Rusek, A., Sawafta, R., Schmitt, H., Schumacher, R. A., Stotzer, R. W., Sutter, R., Takeutchi, F., van Oers, W. T. H., Yamamoto, K., Yamamoto, Y., Yosoi, M., and Zeps, V. J.

Subjects
Nuclear Experiment
Abstract

The E885 collaboration utilized the 1.8 GeV/c K^- beam line at the AGS to accumulate 3 x 10^5 (K^-,K^+) events. Xi hypernuclear states are expected to be produced through the reaction K^- + ^{12}C -> K^+ + ^{12}_{Xi}Be. The measured missing-mass spectrum indicates the existence of a signal below the threshold for free Xi production. Although the resolution was not sufficient to resolve discrete hypernuclear states, the excess of events in the region of missing mass, kinematically inaccessible in free Xi production, is compared to theoretical prediction for ^{12}_{Xi}Be production., Comment: 16 pages 6 figures

Published
1999
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14. Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Caragheorgheopol, Gh., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Detraz, C., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G.F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Ullaland, O., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Published
2016
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15. First observation of the ΣN decay of the S = −2 system

Author

Watanabe, T., Ahn, J. K., Akikawa, H., Aoki, S., Arai, K., Bahk, S. Y., Baik, K. M., Bassalleck, B., Chung, J. H., Chung, M. S., Davis, D. H., Fukuda, T., Hayata, H., Hoshino, K., Ichikawa, A., Ieiri, M., Imai, K., Iwata, Y. H., Iwata, Y. S., Kakita, Y., Kanda, H., Kaneko, M., Kawai, T., Kawasaki, M., Kim, C. O., Kim, J. Y., Kim, S. J., Kim, S. H., Kondo, Y., Kouketsu, T., Lee, Y. L., McNabb, J. W. C., Mitsuhara, M., Nagase, Y., Nagoshi, C., Nakazawa, K., Noumi, H., Ogawa, S., Okabe, H., Oyama, K., Park, H. M., Park, I. G., Parker, J., Ra, Y. S., Rhee, J. T., Rusek, A., Shibuya, H., Sim, K. S., Saha, P. K., Seki, D., Sekimoto, M., Song, J. S., Takahashi, H., Takahashi, T., Takeutchi, F., Tanaka, H., Tanida, K., Tojo, J., Torii, H., Torikai, S., Tsunemi, T., Tovee, D. N., Ushida, N., Yamamoto, K., Yasuda, N., Yang, J. T., Yoon, C. J., Yoon, C. S., Yosoi, M., Yoshida, T., Zhu, L., Pochodzalla, Josef, editor, and Walcher, Thomas, editor

Published
2007
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16. Investigation of <math><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> pairs in the effective mass region near <math><mn>2</mn><msub><mi>m</mi><mi>K</mi></msub></math>

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mari??as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Romero Vidal, A., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Abstract

The DIRAC experiment at CERN investigated in the reaction p(24 GeV/c)+Ni the particle pairs K+K−,π+π−, and pp¯ with relative momentum Q in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of K+K− pairs, obtained by subtracting-using the time-of-flight (TOF) technique-the background from initial Q distributions with K+K− sample fractions more than 70%, 50%, and 30%. The corresponding pair distributions in Q and in its longitudinal projection QL were analyzed first in a Coulomb model, which takes into account only the Coulomb final-state interaction (FSI) and assuming pointlike pair production. This Coulomb model analysis leads to a K+K− yield increase of about four at QL=0.5 MeV/c compared to 100 MeV/c. In order to study contributions from strong interaction, a second more sophisticated model was applied, considering also strong FSI via the resonances f0(980) and a0(980) and a variable distance r* between the produced K mesons besides Coulomb FSI. This analysis was based on three different parameter sets for the pair production. For the 70% subsample and with the best parameters, 3680±370 K+K− pairs were found to be compared to 3900±410 K+K− extracted by means of the Coulomb model. Knowing the efficiency of the TOF cut for background suppression, the total number of detected K+K− pairs was evaluated to be around 40000±10%, which agrees with the result from the 30% subsample. The K+K− pair number in the 50% subsample differs from the two other values by about three standard deviations, confirming—as discussed in the paper—that experimental data in this subsample is less reliable. In summary, the upgraded DIRAC experiment observed increased K+K− production at small relative momentum Q. The pair distribution in Q is well described by Coulomb FSI, whereas a potential influence from strong interaction in this Q region is insignificant within experimental errors.

Published
2022

17. Searching for the H-Dibaryon at Brookhaven

Author

Bassalleck, B., Athanas, M., Barnes, P. D., Berdoz, A., Biglan, A., Birchall, J., Bürger, T., Burger, M., Chrien, R. E., Davis, C., Diebold, G. E., En’yo, H., Fischer, H., Franklin, G. B., Franz, J., Gan, L., Gill, D., Iijima, T., Imai, K., Koran, P., Landry, M., Lee, L., Lowe, J., Magahiz, R., Masaike, A., Meyer, C. A., McCrady, R., Merrill, F., Nelson, J. M., Okada, K., Page, S., Pile, P. H., Quinn, B., Ramsay, D., Rössle, E., Rusek, A., Rozon, M., Sawafta, R., Schmitt, H., Schumacher, R. A., Stearns, R. L., Stotzer, R., Sukaton, R., Sum, V., Sutter, R., Szymanski, J. J., Takeutchi, F., van Oers, W. T. H., Wolfe, D. M., Yamamoto, K., Yosoi, M., Zeps, V., Zybert, R., Mitter, H., editor, Plessas, W., editor, Adam, J., editor, Dobeš, J., editor, Mach, R., editor, Sotona, M., editor, and Dolejší, J., editor

Published
1996
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19. First observation of the ΣN decay of the S = - 2 system

Author

Watanabe, T., Ahn, J. K., Akikawa, H., Aoki, S., Arai, K., Bahk, S. Y., Baik, K. M., Bassalleck, B., Chung, J. H., Chung, M. S., Davis, D. H., Fukuda, T., Hayata, H., Hoshino, K., Ichikawa, A., Ieiri, M., Imai, K., Iwata, Y. H., Iwata, Y. S., Kakita, Y., Kanda, H., Kaneko, M., Kawai, T., Kawasaki, M., Kim, C. O., Kim, J. Y., Kim, S. J., Kim, S. H., Kondo, Y., Kouketsu, T., Lee, Y. L., McNabb, J. W. C., Mitsuhara, M., Nagase, Y., Nagoshi, C., Nakazawa, K., Noumi, H., Ogawa, S., Okabe, H., Oyama, K., Park, H. M., Park, I. G., Parker, J., Ra, Y. S., Rhee, J. T., Rusek, A., Shibuya, H., Sim, K. S., Saha, P. K., Seki, D., Sekimoto, M., Song, J. S., Takahashi, H., Takahashi, T., Takeutchi, F., Tanaka, H., Tanida, K., Tojo, J., Torii, H., Torikai, S., Tsunemi, T., Tovee, D. N., Ushida, N., Yamamoto, K., Yasuda, N., Yang, J. T., Yoon, C. J., Yoon, C. S., Yosoi, M., Yoshida, T., and Zhu, L.

Published
2007
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21. Active target with plastic scintillating fibers for hyperon-proton scattering experiments

Author

Ahn, J.K., Akikawa, H., Arvieux, J., Bassalleck, B., Chung, M.S., En'yo, H., Fukuda, T., Funahashi, H., Golovkin, S.V., Gorin, A.M., Goto, Y., Hanabata, M., Hayakawa, T., Ichikawa, A., Ieiri, M., Imai, K., Ishino, M., Kanda, H., Kim, Y.D., Kondo, Y., Kozarenko, E.N., Kreslo, I.E., Lee, J.M., Masaike, A., Mihara, S., Nakai, K., Nakazawa, K., Ozawa, K., Sato, A., Sato, H.D., Sim, K.S., Tabaru, T., Takeutchi, F., Tlusty, P., Torii, H., Yamamoto, Kenichi, Yokkaichi, S., and Yoshida, M.

Subjects
Protons -- Scattering, Spectrometer -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

An active target with plastic scintillating fibers has been constructed. This active target serves as a production target of hyperons, as well as a scattering target, and works as a 4 [pi]-detector for charged particles. This system is designed for measurements of hyperon-proton scattering for hyperon momenta of several hundred MeV/c. A spectrometer system for the incident beam and outgoing particles of the hyperon production reaction is linked with this target-detector in order to provide triggers for the imaging device of this detector system. As a control of this detector, the decay constant of [[SIGMA].sup.-] hyperon has been evaluated. Index Terms--Active target, hyperon-proton scattering, scintillating fibers.

Published
2002

23. Search for H dibaryon by scintillating-fiber track detector

Author

Ahn, J. K., Aoki, S., Chung, K. S., Chung, M. S., En’yo, H., Fukuda, T., Funahashi, H., Goto, Y., Higashi, A., Ieiri, M., Iijima, T., Iinuma, M., Imai, K., Itow, Y., Lee, J. M., Nagoshi, C., Nomura, I., Makino, S., Masaike, A., Matsuda, Y., Matsuyama, Y., Mihara, S., Omata, K., Park, I. S., Saito, N., Sekimoto, M., Shin, Y. M., Sim, K. S., Susukita, R., Takashima, R., Takeutchi, F., Tlusty, P., Weibe, S., Yokkaichi, S., Yamashita, S., Yoshida, K., Yoshida, M., Yoshida, T., and KEK-E224 Collaboration

Published
1994
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24. Large-x F spin asymmetry inπ 0 production by 200-GeV polarized protons

Author

Adams, D. L., Akchurin, N., Belikov, N. I., Bystricky, J., Corcoran, M. D., Cossairt, J. D., Cranshaw, J., Derevschikov, A. A., En'yo, H., Funahashi, H., Goto, Y., Grachov, O. A., Grosnick, D. P., Hill, D. A., Imai, K., Itow, Y., Iwatani, K., Krueger, K. W., Kuroda, K., Laghai, M., Lehar, F., de Lesquen, A., Lopiano, D., Luehring, F. C., Maki, T., Makino, S., Masaike, A., Matulenko, Yu. A., Meschanin, A. P., Michalowicz, A., Miller, D. H., Miyake, K., Nagamine, T., Nessi-Tedaldi, F., Nessi, M., Nguyen, C., Nurushev, S. B., Ohashi, Y., Onel, Y., Patalakha, D. I., Pauletta, G., Penzo, A., Read, A. L., Roberts, J. B., van Rossum, L., Rykov, V. L., Saito, N., Salvato, G., Schiavon, P., Skeens, J., Solovyanov, V. L., Spinka, H., Takashima, R., Takeutchi, F., Tamura, N., Tanaka, N., Underwood, D. G., Vasiliev, A. N., Villari, A., White, J. L., Yamashita, S., Yokosawa, A., Yoshida, T., Zanetti, A., and FNAL E704 Collaboration

Published
1992
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25. DIRAC: A high resolution spectrometer for pionium detection

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Cima, E., Constantinescu, S., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Evangelou, I., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Giardoni, M., Goldin, D., Gómez, F., Gorin, A., Gortchakov, O., Guaraldo, C., Hansroul, M., Iliescu, M., Zhabitsky, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, V., Kuroda, K.-I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Levisandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manthos, N., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Núñez Pardo, T., Okada, K., Olchevskii, V., Orecchini, D., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Pló, M., Ponta, T., Pop, D., Rappazzo, G.F., Riazantsev, A., Rodriguez, J.M., Rodriguez Fernandez, A., Romero, A., Rykalin, V., Santamarina, C., Saborido, J., Schacher, J., Schuetz, Ch.P., Sidorov, A., Smolik, J., Steinacher, M., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Triantis, F., Trusov, S., Utkin, V., Vázquez Doce, O., Vázquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Published
2003
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26. Searching for the H-Dibaryon at Brookhaven

Author

Bassalleck, B., primary, Athanas, M., additional, Barnes, P. D., additional, Berdoz, A., additional, Biglan, A., additional, Birchall, J., additional, Bürger, T., additional, Burger, M., additional, Chrien, R. E., additional, Davis, C., additional, Diebold, G. E., additional, En’yo, H., additional, Fischer, H., additional, Franklin, G. B., additional, Franz, J., additional, Gan, L., additional, Gill, D., additional, Iijima, T., additional, Imai, K., additional, Koran, P., additional, Landry, M., additional, Lee, L., additional, Lowe, J., additional, Magahiz, R., additional, Masaike, A., additional, Meyer, C. A., additional, McCrady, R., additional, Merrill, F., additional, Nelson, J. M., additional, Okada, K., additional, Page, S., additional, Pile, P. H., additional, Quinn, B., additional, Ramsay, D., additional, Rössle, E., additional, Rusek, A., additional, Rozon, M., additional, Sawafta, R., additional, Schmitt, H., additional, Schumacher, R. A., additional, Stearns, R. L., additional, Stotzer, R., additional, Sukaton, R., additional, Sum, V., additional, Sutter, R., additional, Szymanski, J. J., additional, Takeutchi, F., additional, van Oers, W. T. H., additional, Wolfe, D. M., additional, Yamamoto, K., additional, Yosoi, M., additional, Zeps, V., additional, and Zybert, R., additional

Published
1995
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27. First Measurement of a Long-Lived π^{+}π^{-} Atom Lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Romero Vidal, A., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π+π− atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 μm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, nAL=436−61+157|tot, the lifetime of the 2p state is found to be τ2p=(0.45−0.30+1.08|tot)×10−11 s, not contradicting the corresponding QED 2p state lifetime τ2pQED=1.17×10−11 s. This lifetime value is three orders of magnitude larger than our previously measured value of the π+π− atom ground state lifetime τ=(3.15−0.26+0.28|tot)×10−15 s. Further studies of long-lived π+π− atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

Published
2018

28. First measurement of a long-lived $��^+ ��^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mari��as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Physics::Atomic Physics, Nuclear Experiment (nucl-ex)
Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogen-like $��^+��^-$ atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96~mm and got broken up in the 2.1~\textmu{}m thick platinum foil. Analysing the observed number of atomic pairs, $n_A^L= \left.436^{+157}_{-61}\right|_\mathrm{tot}$, the lifetime of the 2$p$ state is found to be ${��_{2p}=(\left.0.45^{+1.08}_{-0.30}\right|_\mathrm{tot}) \cdot10^{-11}}$s, not contradicting the corresponding QED $2p$ state lifetime ${��_{2p}^\mathrm{QED}=1.17 \cdot 10^{-11}}$s. This lifetime value is three orders of magnitude larger than our previously measured value of the $��^+��^-$ atom ground state lifetime $��=(\left.3.15^{+0.28}_{-0.26}\right|_\mathrm{tot})\cdot 10^{-15}$s. Further studies of long-lived $��^+��^-$ atoms will allow to measure energy differences between $p$ and $s$ atomic states and so to determine $����$ scattering lengths with the aim to check QCD predictions., 7 pages, 8 figures

Published
2018
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29. First Measurement of a Long-Lived π+π− Atom Lifetime

Author

Adeva, B., primary, Afanasyev, L., additional, Anania, A., additional, Aogaki, S., additional, Benelli, A., additional, Brekhovskikh, V., additional, Cechak, T., additional, Chiba, M., additional, Chliapnikov, P. V., additional, Doskarova, P., additional, Drijard, D., additional, Dudarev, A., additional, Dumitriu, D., additional, Fluerasu, D., additional, Gorin, A., additional, Gorchakov, O., additional, Gritsay, K., additional, Guaraldo, C., additional, Gugiu, M., additional, Hansroul, M., additional, Hons, Z., additional, Horikawa, S., additional, Iwashita, Y., additional, Karpukhin, V., additional, Kluson, J., additional, Kobayashi, M., additional, Kruglov, V., additional, Kruglova, L., additional, Kulikov, A., additional, Kulish, E., additional, Lamberto, A., additional, Lanaro, A., additional, Lednicky, R., additional, Mariñas, C., additional, Martincik, J., additional, Nemenov, L., additional, Nikitin, M., additional, Okada, K., additional, Olchevskii, V., additional, Ovsiannikov, V., additional, Pentia, M., additional, Penzo, A., additional, Plo, M., additional, Prusa, P., additional, Rappazzo, G. F., additional, Romero Vidal, A., additional, Ryazantsev, A., additional, Rykalin, V., additional, Saborido, J., additional, Schacher, J., additional, Sidorov, A., additional, Smolik, J., additional, Takeutchi, F., additional, Trojek, T., additional, Trusov, S., additional, Urban, T., additional, Vrba, T., additional, Yazkov, V., additional, Yoshimura, Y., additional, and Zrelov, P., additional

Published
2019
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31. Dirac experiment

Author

Gómez, F., Adeva, B., Afanasev, L., Benayoun, M., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Constantinescu, S., Doudarev, A., Dreossi, D., Drijard, D., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Goldin, D., Gorin, A., Gortchakov, O., Guaraldo, C., Hansroul, M., Hosek, R., Iliescu, M., Jabitski, M., Kalinina, N., Karpoukhine, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Koulikov, A., Kouptsov, A., Krouglov, V., Krouglova, L., Kuroda, K.-I., Lanaro, A., Lapshine, V., Lednicky, R., Leruste, P., Levisandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Nunez Pardo, T., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Plo, M., Ponta, T., Pop, D., Riazantsev, A., Rodriguez, J.M., Rodriguez Fernandez, A., Rykaline, V., Santamarina, C., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Trusov, S., Vazquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Published
2001
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32. Active target-detector with scintillating fibers for hyperon–proton scattering

Author

Ahn, J.K., Akikawa, H., Arvieux, J., Bassalleck, B., Chung, M.S., En’yo, H., Fukuda, T., Funahashi, H., Golovkin, S.V., Gorin, A.M., Goto, Y., Hanabata, M., Hayakawa, T., Ichikawa, A., Ieiri, M., Imai, K., Ishino, M., Kanda, H., Kim, Y.D., Kondo, Y., Kozarenko, E.N., Kreslo, I.E., Lee, J.M., Masaike, A., Mihara, S., Nakai, K., Nakazawa, K., Ozawa, K., Sato, A., Sato, H.D., Sim, K.S., Tabaru, T., Takeutchi, F., Tlustỳ, P., Torii, H., Yamamoto, K., Yokkaichi, S., and Yoshida, M.

Published
2001
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33. Measurement of the $��K$ atom lifetime and the $��K$ scattering length

Author

DIRAC Collaboration, Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

After having announced the statistically significant observation (5.6~$��$) of the new exotic $��K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $��K$ data sample: $��= (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means of a precise relation ($, 18 pages, 17 figures

Published
2017
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37. First measurement of the π+π− atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Constantinescu, S., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Evangelou, I., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Goldin, D., Gómez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Hansroul, M., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Kuroda, K.-I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Levi Sandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manthos, N., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Núñez Pardo, T., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Pló, M., Ponta, T., Pop, D., Rappazzo, G.F., Rodriguez Fernandez, A., Romero, A., Ryazantsev, A., Rykalin, V., Santamarina, C., Saborido, J., Schacher, J., Schuetz, Ch.P., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Trusov, S., Utkin, V., Vázquez Doce, O., Vázquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
Nuclear and High Energy Physics
Published
2005
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38. First $��K$ atom lifetime and $��K$ scattering length measurements

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mari��as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Ponta, T., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

The results of a search for hydrogen-like atoms consisting of $��^{\mp}K^{\pm}$ mesons are presented. Evidence for $��K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $��K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using these results the analysis yields a first value for the $��K$ atom lifetime of $��=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $��K$ scattering length $\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|= \left(0.11_{-0.04}^{+0.09} \right)M_��^{-1}$ ($a_I$ for isospin $I$)., 14 pages, 8 figures

Published
2014
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40. Search for Long-Lived States of $\pi^+\pi^-$ Atoms : Addendum to the DIRAC Proposal

Author

Adeva, B, Afanasyev, L, Anania, A, Aogaki, S, Augsten, K, Batyuk, P, Benelli, A, Brekhovskikh, V, Cechak, T, Chiba, M, Ciortea, C, Curceanu, C, Doskarova, P, Dudarev, A, Dumitriu, D, Drijard, D, Fluerasu, D, Gortchakov, O, Gritsay, K, Guaraldo, C, Gugiu, M, Hansroul, M, Hosek, R, Hons, Z, Iwashita, Y, Karpukhin, V, Kluson, J, Kobayashi, M, Kruglov, V, Kruglova, L, Kulikov, A, Kulish, E, Kuptsov, A, Lamberto, A, Lednicky, R, Martincik, J, Nemenov, L, Nikitin, M, Okada, K, Pentia, M, Plo, M, Prusa, P, Rappazzo, G, Ryazantsev, A, Romero, A, Ronzhin, V, Rykalin, V, Saborido, J, Schacher, J, Shlyapnikov, P, Smolik, J, Takeutchi, F, Trojek, T, Urban, T, Vrba, T, Vazquez, P, Yazkov, V, Yoshimura, Y, Zhabitsky, M, and Zrelov, P

Subjects
Detectors and Experimental Techniques
Abstract

The proposed experiment is a further development of the DIRAC experiment already running at CERN PS. The observation of long-lived (metastable) states of $\pi^+\pi^-$ atoms ($A_{2\pi}$) will be performed with the same setup. This observation opens a possibility to measure the energy difference between $ns$ and $np$ states and to determine the value of the combination $2a_0+a_2$ of S-wave $\pi\pi$ scattering lengths in a model-independent way. In combination with the $A_{2\pi}$ lifetime measurement providing the value $|a_0-a_2|$ DIRAC is in the position to get $a_0$ and $a_2$ separately on the basis of $A_{2\pi}$ data only.

Published
2012

43. Search for Long-Lived States of $\pi^+\pi^-$ Atoms: Addendum to the DIRAC Proposal

Author

Adeva, B, Afanasyev, L, Amsler, C, Anania, A, Aogaki, S, Augsten, K, Benelli, A, Brekhovskikh, V, Cechak, T, Chiba, M, Ciortea, C, Ciocarlan, C, Constantinescu, S, Curceanu, C, Doskarova, P, Dudarev, A, Dumitriu, D, Drijard, D, Enulescu, A, Fluerasu, D, Gortchakov, O, Gritsay, K, Guaraldo, C, Gugiu, M, Hansroul, M, Hosek, R, Hons, Z, Karpukhin, V, Kluson, J, Kobayashi, M, Kulikov, A, Kulish, E, Kuptsov, A, Kruglov, V, Kruglova, L, Kuroda, K, Lamberto, A, Lednicky, R, Martincik, J, Nemenov, L, Nikitin, M, Okada, K, Pentia, M, Plo, M, Prusa, P, Rappazzo, G, Ryazantsev, A, Romero, A, Ronzhin, V, Rykalin, V, Saborido, J, Schacher, J, Shlyapnikov, P, Smolik, J, Takeutchi, F, Tarasov, A, Trojek, T, Urban, T, Vrba, T, Vazquez, P, Yazkov, V, Yoshimura, Y, Zhabitsky, M, and Zrelov, P

Subjects
Detectors and Experimental Techniques
Abstract

The proposed experiment is a further development of the DIRAC experiment already running at CERN PS. Up to now more than 21000 $\pi^+\pi^-$ pairs originated from the $\pi^+\pi^-$ atom ($A_{2\pi}$) breakup were identified and the overall accuracy of the $A_{2\pi}$ lifetime is about 9% in accordance with the DIRAC proposal. This measurement allowed to extract the difference $|a_0-a_2|$ of $s$-wave $\pi\pi$-scattering length with accuracy of 4.3%. The observation of long-lived (metastable) $A_{2\pi}$ states will be performed with the same setup. This observation opens a possibility to measure the energy difference between $ns$ and $np$ states and to determine the value of another combination $2a_0+a_2$ of $\pi\pi$ scattering length in a model-independent way. In combination with the first measurement it allows to get $a_0$ and $a_2$ separately. An additional measurement of the multiple scattering angles in different materials with accuracy better than 1% will be performed in parallel with the observation. This measurement is needed to improve the systematic accuracy in the $A_{2\pi}$ lifetime for the data already collected in 2008--2010.

Published
2011

44. Determination of pi pi scattering lengths from measurement of pi(+)pi(-) atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P. V., Ciocarlan, C., Constantinescu, S., Costantini, S., Curceanu, C., Doskarova, P., Dreossi, D., Drijard, D., Dudarev, A., Ferro-Luzzi, M., Pazos, J. L. F., Torreira, M. G., Gerndt, J., Gianotti, P., Goldin, D., Gomez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kuroda, K. I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Sandri, P. L., Aguera, A. L., Lucherini, V., Maki, T., Manuilov, I., Marin, J., Narjoux, J. L., Nemenov, L., Nikitin, M., Pardo, T. N., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J. M., Plo, M., Ponta, T., Rappazzo, G. F., Riazantsev, A., Rodriguez, J. M., Fernandez, A. R., Vidal, A. R., Ronjin, V. M., Rykalin, V., Saborido, J., Santamarina, C., Schacher, J., Schuetz, C., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M. J., Trojek, T., Trusov, S., Utkin, V., Doce, O. V., Vlachos, S., Voskresenskaya, O., Vrba, T., Willmott, C., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
pion scattering, probability, pionium, elementary atom, dirac experiment, pionium atom, cross-sections, qcd, target
Abstract

The DIRAC experiment at CERN has achieved a sizeable production of pi(+)pi(-) atoms and has significantly improved the precision on its lifetime determination. From a sample of 21 227 atomic pairs, a 4% measurement of the S-wave pi pi scattering length difference |a(0) - a(2)| = (0.2533(-0.0078)(+0.0080)|stat(-0.0073)(+0.0078)|syst)M(pi+)(-1) has been attained, providing an important test of Chiral Perturbation Theory. (C) 2011 Elsevier B.V. All rights reserved. Physics Letters B

Published
2011

45. First observation of long-lived π+π− atoms

Author

Adeva, B., primary, Afanasyev, L., additional, Anania, A., additional, Aogaki, S., additional, Benelli, A., additional, Brekhovskikh, V., additional, Cechak, T., additional, Chiba, M., additional, Chliapnikov, P., additional, Doskarova, P., additional, Drijard, D., additional, Dudarev, A., additional, Duma, M., additional, Dumitriu, D., additional, Fluerasu, D., additional, Gorin, A., additional, Gorchakov, O., additional, Gritsay, K., additional, Guaraldo, C., additional, Gugiu, M., additional, Hansroul, M., additional, Hons, Z., additional, Horikawa, S., additional, Iwashita, Y., additional, Karpukhin, V., additional, Kluson, J., additional, Kobayashi, M., additional, Kruglov, V., additional, Kruglova, L., additional, Kulikov, A., additional, Kulish, E., additional, Kuptsov, A., additional, Lamberto, A., additional, Lanaro, A., additional, Lednicky, R., additional, Mariñas, C., additional, Martincik, J., additional, Nemenov, L., additional, Nikitin, M., additional, Okada, K., additional, Olchevskii, V., additional, Ovsiannikov, V., additional, Pentia, M., additional, Penzo, A., additional, Plo, M., additional, Prusa, P., additional, Rappazzo, G., additional, Romero Vidal, A., additional, Ryazantsev, A., additional, Rykalin, V., additional, Saborido, J., additional, Schacher, J., additional, Sidorov, A., additional, Smolik, J., additional, Takeutchi, F., additional, Tauscher, L., additional, Trojek, T., additional, Trusov, S., additional, Urban, T., additional, Vrba, T., additional, Yazkov, V., additional, Yoshimura, Y., additional, Zhabitsky, M., additional, and Zrelov, P., additional

Published
2015
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46. Evidence for $��K$-atoms with DIRAC

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Benelli, A., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Curceanu, C., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fungueiri��o, J. L., Gerndt, J., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Sandri, P. Levi, Aguera, A. Lopez, Lucherini, V., Manuilov, I., Mari��as, C., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Pl��, M., Rappazzo, G. F., Regenfus, C., Rochet, J., Romero, A., Ronjin, V., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tarasov, A., Tauscher, L., Trojek, T., Trusov, S., Utkin, V., Doce, O. V��zquez, Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

We present evidence for the first observation of electromagnetically bound $��^\pm K^\mp$-pairs ($��K$-atoms) with the DIRAC experiment at the CERN-PS. The $��K$-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the $��^\pm$ and $K^\mp$-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 $\pm$ 54 $��K$-atoms. The mean life of $��K$-atoms is related to the s-wave $��K$-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level., 15 pages, 9 figures

Published
2009
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49. First measurement of the $\pi^+\pi^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Constantinescu, S., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Evangelou, I., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Goldin, D., Gómez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Hansroul, M., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Kuroda, K.-I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Levi Sandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manthos, N., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Núñez Pardo, T., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Pló, M., Ponta, T., Pop, D., Rappazzo, G.F., Rodriguez Fernandez, A., Romero, A., Ryazantsev, A., Rykalin, V., Santamarina, C., Saborido, J., Schacher, J., Schuetz, Ch.P., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Trusov, S., Utkin, V., Vázquez Doce, O., Vázquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., Zhabitsky, M., Zrelov, P., Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE), IFIN-HH, European Organization for Nuclear Research (CERN), Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (INFN, Sezione di Trieste), Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Frascati (LNF), and DIRAC

Subjects
pi(-) mesons, formalism, DIRAC experiment, scattering, Pion scattering, pionium, excitation, elementary atom, pionium atom, matter, High Energy Physics - Experiment, pion scattering, Elementary atom, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Pionium atom, spectrometer, 36.10.-k, 32.70.Cs, 25.80.E, 25.80.Gn, 29.30.Aj, dirac experiment, cross-sections, relativistic elementary atoms, energy
Abstract

The goal of the DIRAC experiment at CERN (PS212) is to measure the $\pi^+\pi^-$ atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the $S$-wave $\pi\pi$ scattering lengths combination $|a_0-a_2|$. Based on part of the collected data we present a first result on the lifetime, $\tau=[2.91 ^{+0.49}_{-0.62}]\times 10^{-15}$ s, and discuss the major systematic errors. This lifetime corresponds to $|a_0-a_2|=0.264 ^{+0.033}_{-0.020} m_{\pi}^{-1}$., Comment: 18 pages, 6 figures

Published
2005
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50. $\Sigma^+$p elastic scattering cross sections in the region of 350$\leq P\Sigma^+\leq 750 MeV/c$ with a scintillating fiber active target

Author

Ahn, J.K., Akikawa, H., Arvieux, J., Bassalleck, B., Chung, M.S., En'Yo, H., Fukuda, T., Funahashi, H., Golovkin, S.V., Gorin, A.M., Goto, Y., Hanabata, M., Hayakawa, T., Ichikawa, A., Ieiri, M., Imai, K., Ishino, M., Kanda, H., Kimi, Y.D., Kondo, Y., Kozarenko, E.N., Kreslo, I.E., Leek, J.M., Masaike, A., Mihara, S., Nakaig, K., Nakazawa, K., Ozawa, K., Sato, A., Sato, H.D., Sim, K.S., Tabaru, T., Takeutchi, F., Tlustý, P., Torii, H., Yamamoto, K., Yokkaichi, S., Yoshida, M., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and KEK-PS E289

Subjects
13.75.Ev, 21.30.Cb, 25.80.Pw, Hyperon–nucleon interaction, Scintillating fiber active target, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Σ+p elastic scattering, Differential cross sections
Abstract

PHASE; A hyperon–nucleon scattering experiment, KEK-PS E289, was carried out at the K2 beam line in KEK. We adopted a scintillating fiber active target as a hydrogen target for hyperon production and subsequent hyperon–nucleon scattering. We collected more data than in a previous experiment, KEK-PS E251. In this paper, the differential cross sections for Σ+p elastic scattering in the incident momentum range from 350 to 750 MeV/c are presented and compared with theoretical predictions from the Nijmegen group (Nijmegen Soft Core 97) and the Kyoto–Niigata group (RGM-FSS and fss2).

Published
2005
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