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51. Nuclear temperature measurement and secondary decay

Author

M. D'Agostino, G. Vannini, M. Azzano, L. Celano, M. J. Huang, A. Ferrero, M. Bruno, J. D. Dinius, Giacomo Vito Margagliotti, L. Martin, C. K. Gelbke, A. Moroni, M. B. Tsang, G. J. Kunde, P. M. Milazzo, P. F. Mastinu, G. Tagliente, W. G. Lynch, I. Iori, R. Rui, M. L. Fiandri, F. Petruzzelli, C. P. Montoya, T. Glasmacher, Hongfei Xi, Nicola Colonna, S. J. Gaff, and F. Gramegna

Subjects
Physics, Phase transition, education.field_of_study, Decay scheme, Isotope, Excited state, Population, Neutron, Atomic physics, Nuclear Experiment, education, Temperature measurement, Excitation
Abstract

In heavy ion collisions, the products produced in the reaction are dominated by their phase space. It is quite common to interpret data by statistical physics. Temperature, which is a basic quantity of any statistical physics, needs to be addressed experimentally. Assuming thermal and chemical equilibrium are reached at freeze out time, two method can be used to measure nuclear temperature. One method is to measure the yields of particle unstable states in correlation experiments, from the ratios of the yields of excited states in the same isotope, temperatures are deduced by applying Bolztman factor1. Another method to measure temperature is based on the double ratios of two isotope pairs2, (y 1/y 2) and (y 3/y 4) differing by the number of neutrons and/ or protons. These two methods are only valid when measured yields are the same as the primary yields. The problem of nuclei temperature has been studied extensively in the last decad. Most work focus on the temperature measurement by excited states method3,4,5,6. These experimental results show that the temperatures deduced from excited states are around 5 MeV. More recently, nuclear temperature was studied by looking double isotope ratios for Au + Au collisions at E/A=600 MeV. The temperatures deduced from double ratio of (Y(6 Li)/Y(7 Li))/((Y(3 He)/Y(4 He)) remain relatively constant as a function of deduced excitation energy for 2.5 ≤ [ E/A ≤ 10 MeV but increase rapidly at E/A ≥ 10 MeV7, indicates a first order liquid gas phase transition. Since the fragments produced in the reaction normally are highly excited. The final isotope distribution could be quite different from primary distribution due to secondary decays, therefore it is very important to calibrate the thermometers used in the experiment due to secondary decay effect. In this report, we will show experimental results for temperature measurements both form excited states population and double isotope ratios. We will also compare experimental data to a model which take care of secondary decays carefully.

Published
1997

52. Understanding proton emission in central heavy-ion collisions

Author

Eugene Gualtieri, A. M. Vander Molen, T. Li, Sherry Yennello, C. P. Montoya, S. J. Gaff, Graham F. Peaslee, T. Glasmacher, C. K. Gelbke, Gary Westfall, M. B. Tsang, G. J. Kunde, R. Pak, R. Lacey, W. J. Llope, L. Martin, M. A. Lisa, C. Schwarz, S. Hannuschke, W. G. Lynch, M. J. Huang, F. Daffin, N. T. B. Stone, Scott Pratt, J. Yee, Wolfgang Bauer, and D. O. Handzy

Subjects
Physics, Nuclear reaction, Baryon, Nuclear physics, Hadron, General Physics and Astronomy, Elementary particle, Fermion, Atomic physics, Proton emission, Nucleon, Charged particle, Nuclear Physics
Abstract

Two-proton correlation functions for central collisions of {sup 36}Ar+{sup 45}Sc at {ital E}/{ital A}=80, 120, and 160 MeV are compared to calculations with the Boltzmann-Uehling-Uhlenbeck (BUU) transport model. Agreement is found at {ital E}/{ital A}=80MeV, but the model predicts too large correlations at {ital E}/{ital A}=120 and 160 MeV. The discrepancy may be due to delayed emission of protons from particle-unstable states not modeled in BUU. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Published
1995

53. Probing toroidal density distributions with two-proton correlation functions?

Author

F. Daffin, D. O. Handzy, C. K. Gelbke, Wolfgang Bauer, S. J. Gaff, and G. J. Kunde

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Proton, Nuclear Theory, Hadron, Elementary particle, Fermion, Breakup, Baryon, Atomic physics, Nuclear Experiment, Nucleon, Nuclear Physics
Abstract

Transport calculations based on the Boltzmann-Uehling-Uhlenbeck (BUU) equation predict the formation of toroidal density distributions for central [sup 36]Ar+[sup 45]Sc collisions at [ital E]/[ital A]=80 MeV. Calculations with the Koonin-Pratt formalism are performed to explore whether the occurrence of such nonspherical breakup configurations could be tested via two-proton correlation measurements. The predicted signal appears detectable, but weak, because most protons emerge early in the reaction when the source is more compact. Contributions from nonzero impact parameters give rise to additional complications.

Published
1994

54. Electroproduction of the Λ(1520) hyperon

Author

L. Farhi, C. Marchand, V. Sapunenko, S. K. Matthews, J. Domingo, E. Wolin, Baile Zhang, Gerard Gilfoyle, J. P. Ball, R. Fatemi, C. Djalali, A. V. Vlassov, D. Doughty, K. S. Egiyan, K. Mikhailov, W. Kim, B. Carnahan, R. W. Major, G. Ricco, P. Stoler, Sylvain Bouchigny, M. D. Mestayer, M. Lucas, M. Eckhause, Jochen Heisenberg, D. Heddle, S. O. Nelson, K. Hicks, D. G. Crabb, G. V. O'Rielly, G. A. Peterson, M. Spraker, R. A. Miskimen, Philip L. Cole, S. Dytman, Thierry Auger, D. Rowntree, V. Muccifora, S. Barrow, G. Asryan, R. A. Niyazov, John T. O'Brien, S. Boiarinov, Michael Dugger, A. R. Reolon, E. Polli, R. C. Minehart, C. A. Meyer, Moshe Gai, P. Corvisiero, S. Stepanyan, D. Branford, J. J. Manak, A. Longhi, M. Guidal, D. G. Jenkins, K. Sabourov, M. Mirazita, Friedrich Klein, R. S. Hicks, Brian Raue, G. Niculescu, J. M. Laget, J. P. Cummings, Dinko Pocanic, S. E. Kuhn, P. Dragovitsch, J. H. Kelley, J. R. Calarco, M. Holtrop, L. Y. Murphy, Volker D. Burkert, A. S. Biselli, Jing Zhao, V. Frolov, M. J. Amaryan, Michael Vineyard, M. Sanzone-Arenhovel, R. A. Demirchyan, F. Sabatié, M. M. Ito, M. Kossov, K. Paschke, Elton Smith, J. Hardie, B. M. Preedom, Laird Kramer, J. Ficenec, L. Ciciani, M. Anghinolfi, K. Beard, A.V. Stavinsky, James Mueller, Federico Ronchetti, N. Pivnyuk, Kalvir S. Dhuga, M. Klusman, P. D. Rubin, G. Capitani, F. W. Hersman, D. J. Tedeschi, J. Napolitano, Y. G. Sharabian, P. Rossi, S. A. Philips, J. Shaw, G. Gavalian, K. L. Giovanetti, B. Asavapibhop, C. Salgado, Larry Weinstein, J. S. McCarthy, S. Pozdniakov, E. Anciant, Z. L. Zhou, Daniel S. Carman, V. B. Gavrilov, G. Audit, A. K. Opper, G. Riccardi, M. Khandaker, Barry Ritchie, R. DeVita, M. Bektasoglu, J. W C McNabb, T. Y. Tung, R. A. Schumacher, Y. Kuang, K. Wang, T. A. Forest, Avraham Klein, G. E. Dodge, P. V. Degtyarenko, K. Kim, I. Niculescu, D. Lawrence, Hall Crannell, Y. V. Efremenko, S. Taylor, G. S. Adams, K. Joo, D. P. Weygand, S. McAleer, J. Hu, J. W. Price, M. Ripani, M. Battaglieri, D. I. Sober, K. Lukashin, E. DeSanctis, M. Witkowski, Bernhard Mecking, Y. Patois, Roy Thompson, A. V. Skabelin, G. S. Mutchler, H. Egiyan, K. A. Griffioen, C. S. Whisnant, M. Taiuti, Shalev Gilad, R. J. Feuerbach, J. Yun, D. Cords, D. Hancock, G. A. Leksin, L. C. Smith, S. J. Gaff, A. Yegneswaran, N. Bianchi, H. R. Weller, Airton Deppman, V. Gyurjyan, J. Connelly, L.C. Dennis, Herbert O. Funsten, S. M. Shuvalov, M. Guillo, A. Coleman, L. Elouadrhiri, W. K. Brooks, L. M. Qin, B. E. Bonner, H. Avakian, W. J. Briscoe, E. Pasyuk, K. Y. Kim, K. Park, R. Clark, A. Empl, O. Pogorelko, T. Smith, C. E. Hyde-Wright, A. Weisberg, Patrick Girard, and V. S. Serov

Subjects
Physics, Baryon, Nuclear physics, Nuclear and High Energy Physics, Meson, Yield (chemistry), Hyperon, Production (computer science), Atomic physics, Coupling (probability), Lambda, Helicity
Abstract

The reaction ep{yields}e'K{sup +}{Lambda}(1520) with {Lambda}(1520){yields}p'K{sup -} was studied at electron beam energies of 4.05, 4.25, and 4.46 GeV, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cos {theta}{sub K{sup +}}, {phi}{sub K{sup +}}, Q{sup 2}, and W dependencies of {Lambda}(1520) electroproduction are presented for the kinematic region 0.9

55. Observation of an Exotic Baryon with S = +1 in Photoproduction from the Proton

Author

L. C. Smith, S. J. Gaff, K. A. Griffioen, Elton Smith, J. R. Ficenec, R. A. Schumacher, G. Gavalian, V. Mokeev, M. Bellis, K. Park, M. Anghinolfi, B. L. Berman, L. M. Qin, James Mueller, P. D. Rubin, Y. G. Sharabian, C. I O Gordon, V. P. Kubarovsky, R. J. Feuerbach, J. Kuhn, Dinko Pocanic, S. E. Kuhn, J. H. Kelley, C. Tur, Roy Thompson, A. Empl, O. Pogorelko, K. Lukashin, M. Klusman, L. Morand, T. A. Forest, S. Stepanyan, E. De Sanctis, R. C. Minehart, C. A. Meyer, A. K. Opper, Shifeng Chen, D. I. Sober, P. Eugenio, M. Taiuti, L. C. Dennis, H. Avakian, P. Heimberg, B. M. Preedom, E. Polli, W. Kim, Daniel S. Carman, G. Audit, J. P. Santoro, P. Stoler, B. Carnahan, F. Sabatié, J. Hu, J. J. Melone, K. Wang, C. Salgado, D. P. Weygand, B. B. Niczyporuk, R. Fatemi, E. Wolin, G. E. Dodge, J. P. Cummings, H. Denizli, N. Pivnyuk, J. Napolitano, A. Longhi, Thierry Auger, A. V. Vlassov, S. O. Nelson, Ji Li, W. J. Briscoe, E. Pasyuk, M. D. Mestayer, M. Kossov, K. Hicks, J. R. Calarco, J. P. Ball, Y. Prok, S. A. Dytman, Susan Taylor, P. V. Degtyarenko, M. Sargsyan, Cynthia Marie Hadjidakis, S. Strauch, J. Connelly, A. V. Skabelin, S. Boiarinov, D. G. Crabb, Michael Dugger, Rakhsha Nasseripour, Alexei V. Klimenko, A. Weisberg, H. O. Funsten, K. S. Egiyan, R. DeVita, J. W C McNabb, M. Osipenko, C. Cetina, K. Mikhailov, Michael Vineyard, I. Niculescu, D. Lawrence, M. Guillo, Patrick Girard, C. S. Whisnant, J. Shaw, V. Gyurjyan, M. Nozar, Michael Wood, Barry Ritchie, K. Beard, M. U. Mozer, S. Mehrabyan, R. W. Major, L. Elouadrhiri, S. A. Morrow, C. Djalali, V. S. Serov, L. Farhi, J. J. Manak, P. Ambrozewicz, Sylvain Bouchigny, K. V. Dharmawardane, I. I. Strakovsky, P. Rossi, Kwangsoo Kim, G. Riccardi, G. S. Mutchler, M. Guidal, G. V. O'Rielly, G. Niculescu, O. P. Dzyubak, R. A. Niyazov, C. Butuceanu, H. Bagdasaryan, Hall Crannell, John T. O'Brien, N. Benmouna, C. Marchand, M. Ripani, D. Hancock, M. Battaglieri, P. Corvisiero, M. Holtrop, Thomas E. Smith, M. Ungaro, W. K. Brooks, R. Bradford, B. A. Mecking, D. G. Jenkins, K. Sabourov, K. Joo, J. Yun, D. Cords, A. Yegneswaran, G. S. Adams, S. McAleer, J. Langheinrich, S. A. Philips, U. Thoma, J. W. Price, M. M. Ito, Laird Kramer, E. Anciant, M. Bektasoglu, M. Khandaker, D. Doughty, F. W. Hersman, D. Heddle, Volker D. Burkert, A. S. Biselli, R. W. Gothe, K. Y. Kim, V. Frolov, L. Ciciani, S. Simionatto, K. L. Giovanetti, B. Asavapibhop, Hovanes Egiyan, M. Spraker, Larry Weinstein, R. A. Miskimen, H. G. Juengst, D. Branford, M. Mirazita, J. M. Laget, J. Lachniet, V. Sapunenko, Valeria Muccifora, Gerard Gilfoyle, D. Rowntree, R. S. Hakobyan, Federico Ronchetti, Philip L. Cole, Friedrich Klein, Brian Raue, P. Dragovitsch, Y. Ilieva, S. Niccolai, J. Hardie, Lei Guo, A.V. Stavinsky, D. J. Tedeschi, Nicola Bianchi, G. A. Peterson, S. Barrow, L. Todor, D. Protopopescu, S. Pozdniakov, M. Garçon, A. Shafi, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS, and Robert, Suzanne

Subjects
Physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Proton, POSITIVE-STRANGENESS, PENTAQUARK, Nuclear Theory, General Physics and Astronomy, FOS: Physical sciences, PENTAQUARK, Pentaquark, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Exotic baryon, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], POSITIVE-STRANGENESS, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The reaction $\gamma p \to \pi^+K^-K^+n$ was studied at Jefferson Lab using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass $M=1555\pm 10$ MeV/c$^2$ was observed in the $nK^+$ invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c$^2$), and its statistical significance is 7.8 $\pm$ 1.0 ~$\sigma$. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by a chiral soliton model for the $\Theta^+$ baryon. In addition, the $pK^+$ invariant mass distribution was analyzed in the reaction $\gamma p\to K^-K^+p$ with high statistics in search of doubly-charged exotic baryon states. No resonance structures were found in this spectrum., Comment: 5 pages, 5 figures, add references

56. Photoproduction of the ω meson on the proton at large momentum transfer

Author

M. Battaglieri, M. Brunoldi, R. De Vita, J. M. Laget, M. Osipenko, M. Ripani, M. Taiuti, G. Adams, M. J. Amaryan, E. Anciant, M. Anghinolfi, D. S. Armstrong, B. Asavapibhop, G. Asryan, G. Audit, T. Auger, H. Avakian, S. Barrow, K. Beard, M. Bektasoglu, B. L. Berman, A. Bersani, N. Bianchi, A. S. Biselli, S. Boiarinov, S. Bouchigny, R. Bradford, D. Branford, W. J. Briscoe, W. K. Brooks, V. D. Burkert, J. R. Calarco, G. P. Capitani, D. S. Carman, B. Carnahan, A. Cazes, C. Cetina, P. L. Cole, A. Coleman, D. Cords, P. Corvisiero, D. Crabb, H. Crannell, J. P. Cummings, E. DeSanctis, P. V. Degtyarenko, R. Demirchyan, H. Denizli, L. Dennis, K. V. Dharmawardane, K. S. Dhuga, C. Djalali, G. E. Dodge, D. Doughty, P. Dragovitsch, M. Dugger, S. Dytman, M. Eckhause, H. Egiyan, K. S. Egiyan, L. Elouadrhiri, L. Farhi, R. J. Feuerbach, J. Ficenec, T. A. Forest, A. P. Freyberger, V. Frolov, H. Funsten, S. J. Gaff, M. Gai, M. Garcon, G. Gavalian, S. Gilad, G. P. Gilfoyle, K. L. Giovanetti, E. Golovach, K. Griffioen, M. Guidal, M. Guillo, L. Guo, V. Gyurjyan, C. Hadjidakis, D. Hancock, J. Hardie, D. Heddle, F. W. Hersman, K. Hicks, R. S. Hicks, M. Holtrop, C. E. Hyde-Wright, M. M. Ito, K. Joo, J. H. Kelley, M. Khandaker, W. Kim, A. Klein, F. J. Klein, A. V. Klimenko, M. Klusman, M. Kossov, L. H. Kramer, Y. Kuang, S. E. Kuhn, J. Lachniet, D. Lawrence, M. Lucas, K. Lukashin, R. W. Major, J. J. Manak, C. Marchand, S. McAleer, J. McCarthy, J. W. C. McNabb, B. A. Mecking, M. D. Mestayer, C. A. Meyer, K. Mikhailov, M. Mirazita, R. Miskimen, V. Mokeev, S. Morrow, M. U. Mozer, V. Muccifora, J. Mueller, G. S. Mutchler, J. Napolitano, S. O. Nelson, S. Niccolai, B. B. Niczyporuk, R. A. Niyazov, M. Nozar, J. T. O’Brien, A. K. Opper, G. Peterson, S. A. Philips, N. Pivnyuk, D. Pocanic, O. Pogorelko, E. Polli, B. M. Preedom, J. W. Price, D. Protopopescu, L. M. Qin, B. A. Raue, A. R. Reolon, G. Riccardi, G. Ricco, B. G. Ritchie, F. Ronchetti, P. Rossi, D. Rowntree, P. D. Rubin, K. Sabourov, C. Salgado, V. Sapunenko, R. A. Schumacher, V. S. Serov, A. Shafi, Y. G. Sharabian, J. Shaw, A. V. Skabelin, E. S. Smith, T. Smith, L. C. Smith, D. I. Sober, M. Spraker, A. Stavinsky, S. Stepanyan, P. Stoler, S. Taylor, D. J. Tedeschi, L. Todor, U. Thoma, R. Thompson, M. F. Vineyard, A. V. Vlassov, K. Wang, L. B. Weinstein, H. Weller, D. P. Weygand, C. S. Whisnant, E. Wolin, M. Wood, A. Yegneswaran, J. Yun, B. Zhang, J. Zhao, and Z. Zhou

Subjects
Physics, Particle physics, Proton, Meson, Hadron, Momentum transfer, Nuclear Theory, High Energy Physics::Phenomenology, General Physics and Astronomy, Gluon, High Energy Physics - Experiment, Nuclear physics, Baryon, Pion, High Energy Physics::Experiment, Nucleon, Nuclear Experiment
Abstract

The differential cross section, $d\sigma/dt$ for $\omega$ meson exclusive photoproduction on the proton above the resonance region ($2.6, Comment: 5 pages, 5 figures

57. Temperature Measurements for Central Au+Au Collisions at A-35MeV

Author

Huang, M. J., Xi, H., Lynch, W. G., Tsang, M. B., Dinius, J. D., Gaff, S. J., Gelbke, C. K., Glasmacher, T., Kunde, G. J., Martin, L., Montoya, C. P., Scannapieco, E., Milazzo, P. M., Azzano, M., Margagliotti, Giacomo, Rui, Rinaldo, Vannini, G., Colonna, N., Celano, L., Tagliente, G., D’Agostino, M., Bruno, M., Fiandri, M. L., Gramegna, F., Ferrero, A., Iori, I., Moroni, A., Petruzzelli, F., Mastinu, P. F., M. J., Huang, H., Xi, W. G., Lynch, M. B., Tsang, J. D., Diniu, S. J., Gaff, C. K., Gelbke, T., Glasmacher, G. J., Kunde, L., Martin, C. P., Montoya, E., Scannapieco, P. M., Milazzo, M., Azzano, Margagliotti, Giacomo, Rui, Rinaldo, G., Vannini, N., Colonna, L., Celano, G., Tagliente, M., D’Agostino, M., Bruno, M. L., Fiandri, F., Gramegna, A., Ferrero, I., Iori, A., Moroni, F., Petruzzelli, and P. F., Mastinu

Subjects
Heavy ions
Abstract

The breakup temperatures for central Au+Au collisions at 35AMeV have been determined from the relative populations of excited states of 5Li, 4He, and 10B fragments and nine double ratios involving the yields of elements with 1≤Z≤6. Unlike results reported at significantly higher energies, all thermometers yield temperatures that are consistent within the experimental uncertainties. Extrapolation of the data to zero impact parameter yields Tem = 4.6±0.4MeV, somewhat lower than the temperature assumed in statistical multifragmentation model calculations which describe most of the other features of this reaction.

Published
1997

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