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151. Measurement of Single Electrons and Implications for Charm Production inAu+AuCollisions atsNN=130GeV

Author

Charles Maguire, Y. Sumi, Wei Tian, D. J. Lim, Josh Moss, M. Tamai, V.A. Onuchin, Minghui Liu, Sean A. Kelly, E. Kistenev, M. Suzuki, Mikhail Ippolitov, Kenneth Francis Read, Agneta Oskarsson, Y. Berdnikov, S. Belikov, P. Pitukhin, Lennart Osterman, Kazuhiro Tanaka, S. N. White, V. S. Pantuev, M. Rosati, M. Velkovsky, Senta Greene, B. Khachaturov, C. L. Woody, V. Bumazhnov, C. P. Singh, Joakim Nystrand, Shunji Nishimura, Klaus Johannes Reygers, S. Garpman, A. Ster, E. O'Brien, Tai Sakuma, S. S. Adler, G. S. Kyle, James Alexander, S. Kametani, M. Ishihara, F. Messer, R. A. Soltz, An.A. Vorobyov, A. A. Vinogradov, Henrik Tydesjö, Junji Tojo, K. Adcox, Y. Tanaka, M. Grosse Perdekamp, H. A. Gustafsson, T. K. Shea, T. C. Sangster, G. Bunce, R. Averbeck, K. S. Sim, P. L. McGaughey, D. E. Fields, Byung-Sik Hong, T. Ushiroda, B. M. Johnson, A. Bazilevsky, J. T. Mitchell, T. E. Miller, B. V. Jacak, T. L. Thomas, M. Kann, L. L. Chavez, W. C. Chang, R. Santo, H. En'yo, W. W. Kinnison, M. J. Leitch, Jiangyong Jia, Y. Goto, Yongsun Kim, P. W. Stankus, Y. Watanabe, A. Denisov, S. Sawada, S. S. Kapoor, T. Ichihara, F. K. Wohn, H. Torii, T. K. Ghosh, E. J. Desmond, I. D. Ojha, M. Hibino, A. A. Rose, Alexandre Lebedev, Ryugo S. Hayano, T. A. Carey, L. Kochenda, S. Markacs, A. Kiyomichi, P. Chung, K. Pope, T. Ferdousi, A. P.T. Palounek, B. R. Schlei, P. J. Kroon, J. M. Burward-Hoy, Roy A. Lacey, J.R. Mahon, Y. Nakada, J. Chiba, A. Franz, S. F. Pate, Y. Riabov, Kenta Shigaki, H. J. Kim, S. Butsyk, D. M. Lee, V. Kochetkov, E. P. Hartouni, E. Taniguchi, G. C. Mishra, David Olle Rickard Silvermyr, Vladimir Samsonov, H. Tsuruoka, I. Otterlund, Vladislav Manko, M. D. Marx, J. S. Haggerty, A. S. Nyanin, A. L. Godoi, S. Y. Kim, Viktor Riabov, M. Chiu, Ajit Kumar Mohanty, J. Chang, T. A. Shibata, A. Soldatov, M. A. Volkov, Takao Sakaguchi, Juergen Thomas, S. K. Mark, P. D. Barnes, O. Dietzsch, Y. J. Kwon, B. K. Nandi, X. Liu, S. Yokkaichi, C. Klein-Boesing, N. N. Ajitanand, David D'Enterria, T. Chujo, I. E. Yushmanov, Hideki Hamagaki, V. Papavassiliou, G. David, Y. Akiba, H. Hara, J. L. Nagle, S. Y. Fung, A. D. Frawley, Dipanwita Dutta, L. Paffrath, S. Esumi, M. S. Chung, R. P. Pisani, E. Vznuzdaev, K. Imai, German Martinez, T. Kohama, B. V. Dinesh, C. A. Ogilvie, F. G. Bellaiche, W. A. Zajc, V. Baublis, Julia Velkovska, Z. Sun, J. Simon-Gillo, T. Peitzmann, Saskia Mioduszewski, Susumu Sato, J. P. Sullivan, T. K. Hemmick, Nikolay Tyurin, Hiroyuki Sako, M. Muniruzzaman, Yasuo Miake, V. Cianciolo, R. K. Choudhury, P. Steinberg, A. G. Hansen, Y. I. Makdisi, H. W. Van Hecke, T. Shiina, S. K. Tuli, H. Delagrange, Zhongfan Liu, S. Bathe, John Hill, K. Oyama, S. H. Aronson, Sergey Fokin, H. Wang, R. E. Mischke, Yves Roland Schutz, C. Pinkenburg, T. C. Awes, Shiv K. Gupta, A. A. Tsvetkov, Jason Newby, K. Yagi, S. Zhou, P. Chand, Jun Kikuchi, Kensuke Homma, E. Melnikov, A. Hoover, S. Botelho, J. M. Heuser, J. Murata, A. Durum, Toru Sugitate, A. Glenn, W. Y. Jang, Markus Merschmeyer, L. Aphecetche, S. Chernichenko, W. Guryn, I. G. Sibiriak, I. Shein, M. J. Tannenbaum, Alexei Khanzadeev, M. Pollack, N. Bruner, E. Stenlund, B. Bassalleck, F. Mühlbacher, L. Ewell, D. S. Brown, E. M. Takagui, B. A. Cole, Z. Li, Athanasios Petridis, F. Matathias, M. Sugioka, D. Bucher, I. Ravinovich, S. Nagamiya, R. S. Towell, F. Plasil, Norio Saito, Akira Masaike, J. Barrette, J. H. Thomas, S. Klinksiek, Yoshio Arai, A. Drees, S. S. Ryu, N. Starinsky, J. Lauret, Aya Sakaguchi, M. J. Bennett, Ju Hwan Kang, N. Hayashi, S. T. Belyaev, D. S. Ho, C. Y. Chi, Wei Xie, G. R. Young, K. El Chenawi, Martin Purschke, D. Kotchetkov, Z. Fraenkel, S. C. Johnson, Y. J. Mao, M. J. Kweon, Atsushi Taketani, Alexander Milov, C. Witzig, D. P. Morrison, V. E. Semenov, A. Deshpande, T. Christ, I. Tserruya, Yu. Efremenko, V. Singh, Y. H. Shin, D. Koehler, K. Kurita, K. Ebisu, S. P. Stoll, M. Sivertz, Hirohiko Sato, Hiroaki Ohnishi, X. He, L. Nikkinen, K. S. Joo, Dong Jo Kim, Takehiko Matsumoto, K. N. Barish, M. Ono, H. Buesching, Yasushi Nagasaka, M. L. Brooks, Xingguo Li, S. P. Sorensen, M. Messer, A. Kozlov, C. Velissaris, R. Seto, Zhedong Zhang, Peter M. Nilsson, J. G. Lajoie, and T. Hachiya

Subjects
Physics, Particle physics, Photon, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Nuclear Theory, Hadron, General Physics and Astronomy, Electron, 01 natural sciences, 7. Clean energy, Spectral line, Nuclear physics, Yield (chemistry), 0103 physical sciences, Transverse momentum, High Energy Physics::Experiment, Charm (quantum number), Nuclear Experiment, 010306 general physics, Relativistic Heavy Ion Collider
Abstract

Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) > 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mub per binary nucleon-nucleon collision.

Published
2002

152. Longitudinal Flow of Protons from(2–8)AGeVCentralAu+AuCollisions

Author

D. Best, C. Law, T. Wienold, Lei Huo, S. Gushue, Morton Kaplan, David Krofcheck, C. Pinkenburg, M. Anderson, Z. Milosevich, N. T. Porile, M. Heffner, S. Wang, D. Keane, P. Chung, E. Hjort, J. E. Draper, R. L. McGrath, Y. M. Liu, T. Case, N. T. B. Stone, W. N. Zhang, J. Whitfield, Kenneth M. Crowe, James Alexander, N. N. Ajitanand, H. G. Ritter, L. S. Schroeder, G. Rai, J. L. Romero, A. C. Das, T. J. M. Symons, J. C. Kintner, R. P. Scharenberg, H. Liu, Roy A. Lacey, A. S. Hirsch, J. Klay, R. Witt, M. L. Gilkes, J. Lauret, B. K. Srivastava, M. Justice, D. L. Olson, W. Caskey, L. Wood, Russell Wells, F. P. Brady, G. Odyniec, M. A. Lisa, S. Y. Panitkin, J. L. Chance, D. Cebra, and Brian Cole

Subjects
Physics, Range (particle radiation), 010308 nuclear & particles physics, General Physics and Astronomy, 01 natural sciences, Nuclear physics, Flow velocity, Flow (mathematics), 0103 physical sciences, Physics::Accelerator Physics, Rapidity, Atomic physics, Thermal model, Nuclear Experiment, 010306 general physics, Beam energy, Energy (signal processing)
Abstract

Rapidity distributions of protons from central ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ collisions measured by the E895 Collaboration in the energy range from $(2--8)A\mathrm{GeV}$ at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, $〈\ensuremath{\beta}\ensuremath{\gamma}{〉}_{L}$, as a function of the logarithm of beam energy.

Published
2002

153. Suppression of Hadrons with Large Transverse Momentum in CentralAu+AuCollisions atsNN=130GeV

Author

J. Chiba, M. Ishihara, A. Denisov, S. Sawada, S. N. White, T. L. Thomas, S. S. Kapoor, A. Franz, H. Torii, R. E. Mischke, Martin Purschke, Hiroaki Ohnishi, L. Aphecetche, Y. Tanaka, S. F. Pate, X. He, H. Tsuruoka, V. Papavassiliou, T. Ichihara, Ryugo S. Hayano, Alexei Khanzadeev, T. K. Shea, H. En'yo, R. A. Soltz, G. C. Mishra, J. Jia, A. Ster, S. Markacs, Akira Masaike, M. Grosse Perdekamp, L. Nikkinen, Y. Riabov, R. S. Towell, D. Kotchetkov, J. H. Thomas, Kenta Shigaki, F. K. Wohn, Alexander Milov, T. K. Ghosh, M. Pollack, N. Bruner, E. Stenlund, S. T. Belyaev, M. Kann, Kwang Souk Sim, Vladislav Manko, C. Witzig, Takao Sakaguchi, I. G. Sibiriak, C. Klein-Boesing, S. S. Adler, G. S. Kyle, E. Taniguchi, H. Buesching, P. Pitukhin, M. J. Bennett, David Olle Rickard Silvermyr, A. S. Nyanin, M. D. Marx, F. Messer, D. J. Lim, V. Kochetkov, Z. Fraenkel, Xingguo Li, N. Hayashi, M. Rosati, I. D. Ojha, Takehiko Matsumoto, S. Nagamiya, Sean A. Kelly, K. N. Barish, An.A. Vorobyov, D. P. Morrison, G. R. Young, C. L. Woody, D. S. Ho, Minghui Liu, C. Y. Chi, A. D. Frawley, M. Suzuki, M. Ono, M. Velkovsky, D. E. Fields, Shunji Nishimura, T. Ushiroda, T. Chujo, K. Kurita, James Alexander, Youngil Kwon, B. V. Jacak, V. E. Semenov, Charles Maguire, Y. Sumi, Wei Tian, T. Christ, N. Starinsky, Senta Greene, B. R. Schlei, K. Adcox, J. Simon-Gillo, M. Sivertz, Kenneth Francis Read, C. P. Singh, B. Khachaturov, Wei Xie, Yasushi Nagasaka, Y. H. Shin, M. Chiu, Ajit Kumar Mohanty, T. A. Carey, A. Deshpande, E. O'Brien, R. Averbeck, A. Kiyomichi, T. Peitzmann, Josh Moss, Tai Sakuma, Saskia Mioduszewski, P. D. Barnes, A. A. Vinogradov, Henrik Tydesjö, M. L. Brooks, K. S. Joo, Byung-Sik Hong, M. Tamai, S. P. Sorensen, P. L. McGaughey, V.A. Onuchin, S. Belikov, Y. Goto, W. Guryn, M. Sugioka, V. Bumazhnov, Peter M. Nilsson, A. Bazilevsky, T. A. Shibata, L. Paffrath, S. K. Tuli, E. Kistenev, Dong Jo Kim, Joakim Nystrand, J. C. Hill, P. J. Kroon, J. M. Burward-Hoy, J. G. Lajoie, H. Wang, Yves Roland Schutz, C. Pinkenburg, N. N. Ajitanand, A. Glenn, Agneta Oskarsson, T. Kohama, A. L. Godoi, J. Lauret, Mikhail Ippolitov, Susumu Sato, M. Messer, Aya Sakaguchi, A. Kozlov, C. Velissaris, T. C. Sangster, Y. Berdnikov, R. Seto, Zhedong Zhang, X. Liu, S. Yokkaichi, Lennart Osterman, Shiv K. Gupta, J. M. Heuser, I. Tserruya, Yu. Efremenko, Kazuhiro Tanaka, V. Singh, B. K. Nandi, M. Muniruzzaman, Y. Akiba, A. G. Hansen, Klaus Johannes Reygers, Y. I. Makdisi, Z. Sun, S. Botelho, Jason Newby, E. Vznuzdaev, J. Murata, E. M. Takagui, B. A. Cole, A. Durum, V. Baublis, S. Esumi, S. Kametani, J. P. Sullivan, E. P. Hartouni, A. A. Rose, Alexandre Lebedev, P. Steinberg, J. Chang, B. V. Dinesh, T. Shiina, W. A. Zajc, D. Koehler, S. Bathe, K. El Chenawi, Y. Nakada, S. K. Mark, K. Ebisu, S. P. Stoll, T. C. Awes, S. C. Johnson, Y. J. Mao, David D'Enterria, M. J. Kweon, D. S. Brown, A. A. Tsvetkov, L. Kochenda, D. M. Lee, Kensuke Homma, S. Y. Fung, E. J. Desmond, E. Melnikov, V. Cianciolo, P. Chand, Jun Kikuchi, O. Dietzsch, Sergey Fokin, Hirohiko Sato, German Martinez, J. T. Mitchell, B. M. Johnson, A. Hoover, S. Chernichenko, B. Bassalleck, F. Mühlbacher, L. Ewell, R. P. Pisani, I. Shein, H. W. Van Hecke, M. Hibino, Nikolay Tyurin, K. Oyama, A. P.T. Palounek, Dipanwita Dutta, Toru Sugitate, F. G. Bellaiche, S. Garpman, S. H. Aronson, M. J. Tannenbaum, J.R. Mahon, H. A. Gustafsson, Julia Velkovska, Z. Li, Atsushi Taketani, T. E. Miller, L. L. Chavez, K. Imai, I. E. Yushmanov, Y. Watanabe, V. S. Pantuev, R. Santo, Viktor Riabov, J. S. Haggerty, S. Y. Kim, Juergen Thomas, I. Ravinovich, F. Plasil, A. Soldatov, P. Chung, K. Pope, D. Bucher, S. S. Ryu, Junji Tojo, R. K. Choudhury, W. C. Chang, H. Delagrange, Hiroyuki Sako, W. W. Kinnison, M. J. Leitch, K. Yagi, Roy A. Lacey, S. Zhou, Markus Merschmeyer, Norio Saito, S. Butsyk, Yoshio Arai, Vladimir Samsonov, I. Otterlund, H. Hara, J. L. Nagle, M. S. Chung, Hyun-Chul Kim, M. A. Volkov, Hideki Hamagaki, G. David, C. A. Ogilvie, J. Kang, T. K. Hemmick, Yasuo Miake, Yongsun Kim, P. W. Stankus, Zhongfan Liu, W. Y. Jang, G. Bunce, T. Ferdousi, Athanasios Petridis, F. Matathias, J. Barrette, S. Klinksiek, and A. Drees

Subjects
Physics, Range (particle radiation), Particle physics, 010308 nuclear & particles physics, Nuclear Theory, Hadron, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Central region, Spectral line, Nuclear physics, Pion, 0103 physical sciences, Transverse momentum, Nuclear Experiment, 010306 general physics, Jet quenching, Scaling
Abstract

Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 Gev/c < P-T < 5 GeV/c have been measured by the PHENIX experiment at RHIC in Au + Au collisions at rootS(NN) = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p + p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p + p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.

Published
2001

154. Pion Imaging at the AGS

Author

S. Wang, S. Gushue, Z. Milosevich, D. L. Olson, W. Caskey, N. N. Ajitanand, F. P. Brady, Kenneth M. Crowe, M. A. Lisa, M. Justice, Y. M. Liu, Lei Huo, Brian Cole, R. Witt, C. Pinkenburg, T. Wienold, J. L. Chance, D. Cebra, B. K. Srivastava, Morton Kaplan, J. C. Kintner, Xiaodong Yang, N. T. B. Stone, A. S. Hirsch, T. J. M. Symons, S. Y. Panitkin, N. T. Porile, J. Whitfield, E. Hjort, G. Odyniec, L. S. Schroeder, T. Case, Y. Zhang, R. L. McGrath, M. L. Gilkes, L. Wood, James Alexander, J. L. Romero, Russell Wells, H. Liu, J. E. Draper, A. C. Das, H. G. Ritter, J. L. Klay, Roy A. Lacey, M. Heffner, W. N. Zhang, Michael W. Anderson, R. P. Scharenberg, G. Rai, D. Keane, P. Chung, D. Best, and David Krofcheck

Subjects
Physics, Nuclear physics, Pion, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Source imaging analysis was performed on two-pion correlations in central Au + Au collisions at beam energies between 2 and 8$A$ GeV. We apply the imaging technique by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. We found that extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional HBT analysis., Talk given at Bologna 2000 - Structure of the Nucleus at the Dawn of the Century, Bologna, Italia, May 29 - June 3, 2000

Published
2000

155. Isotropic emission components in splintering central collisions:(17−115)AMeV40Ar+Cu,Ag, Au

Author

A. M. Vander Molen, N. N. Ajitanand, Eugene Gualtieri, Rulin Sun, A. Elmaani, P. A. DeYoung, John M. Alexander, S. D. Sundbeck, J. Lauret, Ludwik Kowalski, E. Colin, G. D. Westfall, C. J. Gelderloos, Roy A. Lacey, S. Hannuschke, K. L. Drake, J. A. Jaasma, E. Norbeck, N. T. B. Stone, R. Pak, M. A. Barton, M. Stern, D. Guinet, L. B. Yang, Graham F. Peaslee, and J. Yee

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, Isotropy, Evaporation, chemistry.chemical_element, Kinetic energy, Copper, Spectral line, Entrance channel, Nuclear physics, chemistry, Atomic physics, Nuclear Experiment, Energy (signal processing)
Abstract

The ensemble of charged isotropically emitted ejectiles is studied for central collisions of $(17\ensuremath{-}115)A$ MeV ${}^{40}\mathrm{Ar}\mathrm{}+\mathrm{}\mathrm{Cu},$ Ag, Au. Measurements of average multiplicities, spectral slopes, and masses of the heaviest fragments are compared to statistical models for multifragmentation or sequential evaporation. The multifragmentation models predict much more complete nuclear disassembly than is observed. The evaporation model reproduces the data much more closely except for the spectra of $Z=1$ ejectiles. The kinetic energies of $Z=1$ and 2 ejectiles are much less than found for $1A$ GeV ${}^{197}\mathrm{Au}{+}^{12}\mathrm{C}$ for similar energy depositions. Entrance channel dynamics seem to affect the isotropic emission ensembles, often taken to define an equilibrated emission source.

Published
2000

156. Nuclear disassembly in violent central collisions at intermediate energies:(65−115)AMeV40Ar+Cu,Ag, Au

Author

Eugene Gualtieri, N. N. Ajitanand, A. Elmaani, C. J. Gelderloos, R. Pak, Paul DeYoung, M. Stern, N. T. B. Stone, D. Guinet, Graham F. Peaslee, L. B. Yang, A. M. Vander Molen, S. Hannuschke, J. Lauret, S. D. Sundbeck, John M. Alexander, Rulin Sun, G. D. Westfall, J. A. Jaasma, K. L. Drake, Ludwik Kowalski, J. Yee, E. Norbeck, E. Colin, M. A. Barton, and Roy A. Lacey

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics
Published
2000

157. The NA61/SHINE Collaboration

Author

V. P. Kondratiev, Fotis K. Diakonos, A. Wojtaszek, A. Marchionni, T. Palczewski, S. Igolkin, Jan Kisiel, A. I. Malakhov, T. Montaruli, K. Nishikawa, T. Kobayashi, A. Meregaglia, Ioana Codrina Maris, M. Tada, K. U. Choi, R. Ulrich, Ralph Engel, J. Blümer, Biagio Rossi, Vladimir Vechernin, Z. Fodor, Gyorgy Vesztergombi, André Rubbia, M. Vassiliou, S. Kowalski, D. P. Kikola, A. Haungs, P. Mijakowski, M. Słodkowski, N. Abgrall, Andras Laszlo, A. Marcinek, S.A. Bunyatov, M. Messina, J. Stepaniak, A. G. Asryan, Antonio Ereditato, W. Zipper, P. Christakoglou, P. A. Naumenko, G. Pálla, M. Posiadala, M. Kirejczyk, G. A. Feofilov, R. Planeta, T. R. Schuster, Andrew Ivanov, M. B. Golubeva, A. Grzeszczuk, J. Pluta, E. Rondio, V. Nikolic, G. Stefanek, P. Seyboth, T. Sekiguchi, M. K. Mitrovski, T. Hasegawa, Jean Willy Andre Cleymans, Dieter Røhrich, K. Kadija, J. Argyriades, A. Bubak, R. Tsenov, W. Dominik, Katarzyna Grebieszkow, R. S. Kolevatov, M. Szuba, S. Murphy, A. N. Sissakian, St Mrówczyński, P. Przewlocki, W. Rauch, A. Ferrero, A. B. Kurepin, J. Brzychczyk, J. Dumarchez, G. L. Melkumov, M. Roth, B. A. Popov, F. Guber, Roy A. Lacey, Viktor Matveev, C. Strabel, B. Baatar, Antoni Aduszkiewicz, T. Matulewicz, A. Taranenko, N. Katrynska, Marek Gaździcki, T. Antičić, M. Shibata, Alexander Sorin, M. Ravonel, I. Szentpetery, A. Sadovsky, K. Sakashita, R. Renfordt, N. G. Antoniou, V. V. Lyubushkin, Apostolos Panagiotou, H. Stroebele, W. Peryt, Maciej Rybczyński, D. Derkach, Laszlo Boldizsar, Zbigniew Wlodarczyk, P. Staszel, E. Skrzypczak, D. Kielczewska, V. I. Kolesnikov, T. Nakadaira, D. Kolev, A. Blondel, A. Bravar, A. Ivashkin, B. Andrieu, P. Chung, Z. Majka, M. Unger, and Tatjana Susa

Subjects
Physics, Nuclear and High Energy Physics, Visual arts
Published
2009

158. Odd-evenZisospin anomaly in heavy-ion reactions

Author

A. M. Vander Molen, W. A. Friedman, E. Norbeck, Roy A. Lacey, A. Nadasen, L. B. Yang, Sherry Yennello, N. T. B. Stone, M. L. Miller, O. Bjarki, D. J. Magestro, R. Pak, F. D. Ingram, and G. D. Westfall

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Isospin, Heavy ion, Anomaly (physics)
Published
1999

159. The Bombarding Energy Dependence of π- Inteferometry at the Ags

Author

Xiaodong Yang, A. S. Hirsch, J. L. Romero, G. Rai, J. L. Chance, D. Cebra, I. Chemakin, J. Klay, D. Best, B. Caskey, K.M. Crowe, N. T. B. Stone, E. LeBras, R. Witt, David Krofcheck, P. Brady, S. Gushue, Y. M. Liu, T. Case, R. Wells, D. L. Olson, R. Soltz, Yanxi Zhang, C. Pinkenburg, D. Keane, P. Chung, L. S. Schroeder, V. Cianciolo, S. Wang, M. A. Lisa, L. Wood, N. N. Ajitanand, S. Y. Panitkin, J. E. Draper, R. Scharenburg, M. Justice, N. T. Porile, M. Heffner, B. K. Srivastava, Brian Cole, R. L. McGrath, T. J. M. Symons, H. Hiejima, J. C. Kintner, A. C. Das, H. Liu, Roy A. Lacey, J. Whitfield, T. Wienold, Morton Kaplan, James Alexander, H. G. Ritter, J. Lauret, M. Gilkes, E. L. Hjort, Lei Huo, and W. M. Zhang

Subjects
Excitation function, Nuclear physics, Physics, Correlation function (statistical mechanics), Time projection chamber, Reaction dynamics, Nuclear Theory, Plasma, Sensitivity (control systems), Nuclear Experiment, Energy (signal processing), Intensity (physics)
Abstract

We present a preliminary excitation function of π - intensity inteferometry at AGS energies (2-8 AGeV). The sensitivity of the multidimensional correlation functions to both the geometry and dynamics of the hot pionemitting system provide a stringent test of transport models of heavy ion collisions. Detailed comparisons are performed with the RQMD transport model, both with and without an explicit nuclear meanfield. These comparisons suggest that the evolution in the reaction dynamics with beam energy is different in the model and the data. A suggested signal of the onset of the transition to quark-gluon plasma in the inteferometry excitation function is not observed.

Published
1999

160. The E895 π− Correlation Analysis — A Status Report

Author

Lei Huo, W. M. Zhang, S. Y. Panitkin, Y. M. Liu, S. Wang, M. L. Gilkes, T. J. M. Symons, J. E. Draper, R. Scharenburg, E. Hjort, T. Case, R. Witt, T. Wienold, D. Keane, P. Chung, James Alexander, E. LeBras, Morton Kaplan, B. K. Srivastava, A. C. Das, N. T. Porile, Z. Milosevic, L. Wood, Russell Wells, H. Liu, Roy A. Lacey, G. Rai, R. L. McGrath, N. N. Ajitanand, H. G. Ritter, J. L. Romero, M. Heffner, D. Best, N. T. B. Stone, Xiaodong Yang, L. S. Schroeder, David Krofcheck, A. S. Hirsch, I. Chemakin, B. Caskey, J. Whitfield, V. Cianciolo, Kenneth M. Crowe, R. Soltz, H. Hiejima, J. C. Kintner, Y. Zhang, M. Justice, J. Lauret, D. L. Olson, M. A. Lisa, J. L. Chance, D. Cebra, C. Pinkenburg, P. Brady, S. Gushue, and Brian Cole

Subjects
Physics, High Energy Physics::Phenomenology, Nuclear Theory, Hadron, Nucleation, Degrees of freedom (physics and chemistry), Plasma, Status report, Ion, Nuclear physics, Correlation function, Correlation analysis, High Energy Physics::Experiment, Nuclear Experiment
Abstract

A primary goal of high-enery heavy ion physics is to create and study the quark-gluon plasma (QGP), a phase of matter in which partonic- instead of hadronic- degrees of freedom describe the system. Several transport, hydrodynamic, and nucleation theories1,2,3,4 suggest that energy densities achieved in central collisions between heavy ions at AGS energies may be sufficient to create the QGP.

Published
1998

161. Disappearance of Elliptic Flow, a new probe for the nuclear equation of state

Author

J. M. Alexander, R. L. McGrath, P. Chung, Pawel Danielewicz, Pol Bernard Gossiaux, C. Pinkenburg, Roy A. Lacey, Laboratoire SUBATECH Nantes (SUBATECH), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes)

Subjects
Excitation function, Physics, Phase transition, Nuclear Theory, 010308 nuclear & particles physics, Critical phenomena, Hadron, Elliptic flow, FOS: Physical sciences, General Physics and Astronomy, Nuclear equation of state, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear matter, 01 natural sciences, 7. Clean energy, Nuclear Theory (nucl-th), Nuclear physics, 0103 physical sciences, Quark–gluon plasma, High Energy Physics::Experiment, 010306 general physics, Nuclear Experiment
Abstract

Using a relativistic hadron transport model, we investigate the utility of the elliptic flow excitation function as a probe for the stiffness of nuclear matter and for the onset of a possible quark-gluon-plasma (QGP) phase-transition at AGS energies 1 < E_Beam < 11 AGeV. The excitation function shows a strong dependence on the nuclear equation of state, and exhibits characteristic signatures which could signal the onset of a phase transition to the QGP., 11 pages, 4 Postscript figures, uses epsf.sty, submitted to Physical Review Letters

Published
1998

162. Momentum dependence of the nuclear mean field from peripheral heavy-ion collisions

Author

J. Lauret, R. Pak, W. J. Llope, N. T. B. Stone, Gary Westfall, A. Nadasen, S. Hannuschke, O. Bjarki, A. M. Vander Molen, and Roy A. Lacey

Subjects
Physics, Momentum, Nuclear and High Energy Physics, Transverse plane, Mean field theory, Plane (geometry), Heavy ion, Impact parameter, Atomic physics, Nuclear matter, Energy (signal processing), Nuclear Physics
Abstract

The energy at which the collective transverse flow in the reaction plane disappears, the balance energy ${\mathit{E}}_{\mathrm{bal}}$, is found to increase linearly as a function of impact parameter for $^{40}\mathrm{Ar}$${+}^{45}$Sc reactions. Comparison of our measured values of ${\mathit{E}}_{\mathrm{bal}}$(b) with predictions from quantum molecular dynamics (QMD) model calculations agrees better with an approach incorporating momentum dependence in the nuclear mean field. \textcopyright{} 1996 The American Physical Society.

Published
1996

163. Impact parameter dependence of the disappearance of transverse flow in nuclear collisions

Author

Alice Mignerey, Gary Westfall, S. Hannuschke, Roy A. Lacey, J. Yee, Darren Craig, J. Lauret, W. J. Llope, N. T. B. Stone, D. E. Russ, R. Pak, A. M. Vander Molen, and Eugene Gualtieri

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Transverse plane, Flow (mathematics), Plane (geometry), Impact parameter, Atomic physics, Kinetic energy, Quantum molecular dynamics, Energy (signal processing), Nuclear Physics
Abstract

The impact parameter dependence of the disappearance of directed transverse flow has been investigated for $^{40}\mathrm{Ar}$+$^{45}\mathrm{Sc}$ reactions using the Michigan State University $4\ensuremath{\pi}$ Array upgraded with the High Rate Array (HRA). The energy at which collective transverse flow in the reaction plane disappears, the balance energy (${E}_{\mathrm{bal}}$), is found to increase approximately linearly as a function of impact parameter. Comparison of our measured values of ${E}_{\mathrm{bal}}(b)$ shows agreement with predictions of Quantum Molecular Dynamics (QMD) model calculations.

Published
1996

164. Isospin dependence of collective transverse flow in nuclear collisions

Author

A. Nadasen, D. E. Russ, P. Pogodin, A. M. Vander Molen, Bao-An Li, Sherry Yennello, O. Bjarki, N. T. B. Stone, M. Steiner, R. Pak, J. A. Brown, Gary Westfall, E. Norbeck, L. B. Yang, Roy A. Lacey, W. Benenson, and S. Hannuschke

Subjects
Physics, Particle physics, Physics::Medical Physics, Nuclear Theory, General Physics and Astronomy, Function (mathematics), Nuclear matter, Nuclear physics, Transverse plane, Flow (mathematics), Isospin, Neutron, Sensitivity (control systems), Nuclear Experiment, Nucleon, Nuclear Physics
Abstract

Collective transverse flow of nuclear matter was measured as a function of the ratio of neutrons to protons ( $N/Z$) of the interacting system for the first time. The collisions of three isotopically pure beams of $A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}58\mathrm{nuclei}$ with two $A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}58\mathrm{targets}$ were studied at 55 MeV/nucleon. The results for the flow variables demonstrate the sensitivity of transport models to elementary aspects of the nucleon-nucleon collisions.

Published
1996

165. The Impact Parameter Dependence of the Disappearance of Flow

Author

D. E. Russ, Roy A. Lacey, N. T. B. Stone, Eugene Gualtieri, S. Hannuschke, Darren Craig, J. Yee, A. M. Vander Molen, W. J. Llope, R. Pak, G. D. Westfall, Alice Mignerey, and J. Lauret

Subjects
Nuclear physics, High rate, Physics, Geometric efficiency, Detector, Transverse momentum, Solid angle, Polar, Impact parameter, Nucleon
Abstract

The Michigan State University 4π Array has been recently upgraded to include the High Rate Array (HRA), a close-packed 45 element phoswich array which covers laboratory polar angles from ≈ 3° to ≈ 18°. The HRA subtends all solid angle between the Maryland Forward Array and the detectors of the main Ball resulting in ≈ 90% geometric efficiency for the entire array. With this improved detector configuration, we studied the reaction 40Ar + 45Sc at beam energies from 35 to 115 MeV/nucleon. We present preliminary results on the impact parameter dependence of the disappearance of flow in nuclear collisions, extending the systematics of our previous work.

Published
1996

166. The Disappearance of Fusion/Fission

Author

N. T. B. Stone, Eugene Gualtieri, E. Norbeck, R. Pak, Sherry Yennello, A. Nadasen, Roy A. Lacey, A. M. Vander Molen, J. S. Winfield, T. Li, J. Yee, W. J. Llope, S. Hannuschke, Darren Craig, and Gary D. Westfall

Subjects
Nuclear physics, Physics, Fusion, Fission, Nuclear Theory, Observable, Fusion fission, Nuclear Experiment, Nucleon, High momentum, Charged particle, Shape analysis (digital geometry)
Abstract

The disappearance of fusion/fission has been studied for reactions of 40Ar + 232Th at incident energies ranging from 15 to 115 MeV/nucleon using the MSU 4π Array. We have studied these reactions using a variety of observables including fission fragment opening angles, fission fragment azimuthal correlations, intermediate mass fragment and light charged particle production, and event shape analysis. We observe a change in the decay characteristics of high momentum linear transfer collisions as a function of incident energy from fission-like to multifragment emission.

Published
1996

167. Time relationships between direct particle emission and fragmentation: A probe for nuclear expansion prior to fragment freeze-out

Author

N. N. Ajitanand, María-Ester Brandan, A. Elmaani, F. Merchez, A. Giorni, E. Bauge, D. Rebreyend, J. M. Alexander, C. J. Gelderloos, Brigitte Cheynis, D. Drain, A. Menchaca-Rocha, L. Kowalski, Roy A. Lacey, D. Heuer, Annick Lleres, J. B. Viano, C. Pastor, B. Chambon, T. Ethvignot, S. Kox, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Physics, Particle emission, Fragmentation (mass spectrometry), Deuterium, General Physics and Astronomy, Atomic physics, Nuclear Experiment, Spectral line, Delay time
Abstract

A previously unexploited experimental observable is used to explore emission times for intermediate mass fragments relative to directly emitted ${}^{2}\mathrm{H}$ and ${}^{3}\mathrm{H}$ particles. Small-angle correlations are reported in central collisions for $34A\phantom{\rule{0ex}{0ex}}\mathrm{MeV}$ ${}^{40}\mathrm{Ar}{+}^{\mathrm{nat}}\mathrm{Ag}$. High-velocity ${}^{3}\mathrm{H}$ and ${}^{2}\mathrm{H}$ particles follow a direct emission scenario with mean lifetime $\ensuremath{\tau}\ensuremath{\sim}30\ensuremath{-}60\phantom{\rule{0ex}{0ex}}\mathrm{fm}/c$. Fragmentation to Li is characterized by $\ensuremath{\tau}\ensuremath{\sim}120\mathrm{fm}/c$. Current model calculations suggest a delay time of $\ensuremath{\sim}100\ensuremath{-}200\phantom{\rule{0ex}{0ex}}\mathrm{fm}/c$ for expansion of the central collision zone prior to the onset of ``freeze-out'' into fragments. But the observed velocity difference spectra limit the delay time to $\ensuremath{\lesssim}50\mathrm{fm}/c$ for expansion between direct emission and fragmentation.

Published
1995

168. The sphericity of central heavy-ion reactions

Author

S. Hannuschke, Darren Craig, C. M. Mader, J. Lauret, A. Nadasen, G. Peilert, A. M. Vander Molen, R. Pak, Wolfgang Bauer, J. Yee, N. T. B. Stone, Sherry Yennello, G. D. Westfall, E. Norbeck, Roy A. Lacey, T. Li, W. J. Llope, and Eugene Gualtieri

Subjects
Physics, Nuclear and High Energy Physics, Projection (relational algebra), Heavy ion, Experimental methods, Impact parameter, Atomic physics, Nucleon, Hybrid model, Beam (structure), Sphericity
Abstract

We have experimentally studied small impact parameter heavy-ion collisions in the (nearly) symmetry entrance channels $^{12}\mathrm{C}$${+}^{12}$C, $^{20}\mathrm{Ne}$${+}^{27}$Al, $^{40}\mathrm{Ar}$${+}^{45}$Sc, $^{84}\mathrm{Kr}$${+}^{93}$Nb, and $^{129}\mathrm{Xe}$${+}^{139}$La, each at many intermediate beam energies. The results from a number of analyses based on a projection of the ``shapes'' of the experimental events called the sphericity are presented. Comparisons of the relative efficiencies of various experimental methods for the selection of central events are made. The importance of autocorrelations between the sphericity and the various impact-parameter--dependent variables is evaluated. Searches for beam energy-dependent transitions from sequential binary disassembly to multifragmentation in the central events are described. Comparisons to dynamic and hybrid model code calculations will be discussed. The average sphericities of the intermediate mass fragments (IMF's, for which 3\ensuremath{\le}Z\ensuremath{\lesssim}20), are presented. The possibility that the IMF emission occurs following the formation of transient toroidal or disk-like geometries in the central events is explored. Increases in the average sphericities of the central events for increasing beam energies are observed which is attributed to transitions from sequential binary disassembly to multifragmentation. The transitional beam energies for the central $^{40}\mathrm{Ar}$${+}^{45}$Sc, $^{84}\mathrm{Kr}$${+}^{93}$Nb, and $^{129}\mathrm{Xe}$${+}^{139}$La reactions are near \ensuremath{\sim}50, \ensuremath{\sim}40, and \ensuremath{\sim}40 MeV/nucleon, respectively.

Published
1995

169. Tracking fission-like processes in central collisions of $^{40}$Ar + $^{232}$Th: E = 15-115 A MeV

Author

J. S. Winfield, Eugene Gualtieri, S. Hannuschke, Darren Craig, A. Nadasen, N. T. B. Stone, T. Li, A. M. Vander Molen, W. J. Llope, Roy A. Lacey, G. D. Westfall, J. Yee, R. Pak, E. Norbeck, and Sherry Yennello

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Range (particle radiation), Coincident, Fission, Nuclear Theory, Atomic physics, Nuclear Experiment, Tracking (particle physics), Charged particle, Beam (structure), Nuclear Physics
Abstract

Fission-like fragments and coincident charged particles have been measured in a 4π geometry over a wide energy range (15–115 A MeV) for the reaction 40 Ar+ 232 Th. The exclusive folding angle distribution data provide direct evidence that fission-like processes following incomplete-fusion are still an appreciable exit channel for beam energies as high as 115 A MeV.

Published
1995

170. Mass dependence of critical behavior in nucleus-nucleus collisions

Author

Eugene Gualtieri, Sherry Yennello, A. Nadasen, Wolfgang Bauer, Roy A. Lacey, Gary Westfall, E. Norbeck, R. Pak, R. S. Tickle, J. S. Winfield, S. Hannuschke, Darren Craig, T. Li, J. Yee, and A. M. Vander Molen

Subjects
Physics, Nuclear and High Energy Physics, Proton, Computer Science::Information Retrieval, Lambda, Kinetic energy, Power law, Spectral line, Physics::Accelerator Physics, Atomic physics, Nuclear Experiment, Nucleon, Energy (signal processing), Excitation
Abstract

The {ital Z} distributions of fragments emitted from central collisions of {sup 40}Ar+{sup 45}Sc at beam energies from 15 to 115 MeV/nucleon have been fitted to power laws {sigma}({ital Z}){proportional_to}{ital Z}{sup {minus}{lambda}}. The {lambda} parameter reaches a minimum at a beam energy of 23.9{plus_minus}0.7 MeV/nucleon. A percolation model calculation reproduces the observed {ital Z} distributions for all beam energies, using the mean excitation energy as extracted from proton kinetic energy spectra. We extract the critical value of the deposited excitation energy for our system and make predictions for the dependence of this quantity on the size of the fragmenting system.

Published
1994

171. PHENIX measurements of higher order flow harmonics in Au+Au collisions at \boldsymbol{\sqrt{s_{{\rm NN}}} = 200} GeV

Author

Roy A. Lacey

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Intrinsic viscosity, Plasma, Physics::Fluid Dynamics, Nuclear physics, Viscosity, Strange matter, Flow (mathematics), Harmonics, Quark–gluon plasma, Nuclear Experiment, Anisotropy
Abstract

Flow coefficients vn for n = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at GeV, are presented. They indicate the expected growth of viscous damping for sound propagation in the quark–gluon plasma (QGP) produced in these collisions. Hydrodynamical model comparisons which include the effects of initial state geometry fluctuations highlight the role of higher harmonics (vn, n > 2) as a constraint for disentangling the effects of viscosity and initial conditions and suggest a small specific viscosity for the QGP.

Published
2011

172. Observation of lifetime effects in two-proton correlations for well-characterized sources

Author

W. G. Gong, Eugene Gualtieri, W. G. Lynch, Roy A. Lacey, M. A. Lisa, Scott Pratt, G. D. Westfall, T. Reposeur, J. Yee, Sherry Yennello, C. K. Gelbke, Graham F. Peaslee, S. Hannuschke, P. Decowski, T. Li, and A. M. Vander Molen

Subjects
Baryon, Physics, Nuclear reaction, Proton, Computer Science::Information Retrieval, Hadron, General Physics and Astronomy, Elementary particle, Fermion, Radius, Atomic physics, Nuclear Experiment, Nucleon
Abstract

Differences between longitudinal and transverse two-proton correlation functions, consistent with finite lifetime effects, are observed for central [sup 36]Ar+[sup 45]Sc collisions at [ital E]/[ital A]=80 MeV. The correlations between two protons emitted with low total momenta are consistent with emission from a source of Gaussian radius [ital r][sub 0][approx]4.7[plus minus]0.3 fm and characteristic lifetime [tau][approx]25[plus minus]15 fm/[ital c].

Published
1993

173. Excitation of giant resonances in $^{208}$Pb $^{120}$Sn $^{90}$Zr and $^{60}$Ni by 84 MeV/nucleon $^{17}$O ions

Author

A. Gillibert, J. Barrette, B. Fernandez, S. K. Mark, Y. Blumenfeld, A. van der Woude, P. Roussel-Chomaz, J.P. Garron, J. Gastebois, J. A. Scarpaci, J.C. Roynette, R. Liguori Neto, A. Miczaika, T. Suomijärvi, N. Frascaria, N. Alamanos, F. Auger, R. Turcotte, Roy A. Lacey, A.M. van den Berg, L. Rochais, D. Pierroutsakou, Institut de Physique Nucléaire d'Orsay (IPNO), and 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)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Isoscalar, Nuclear Theory, Resonance, Coulomb excitation, Inelastic scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, 0103 physical sciences, Quadrupole, Sum rule in quantum mechanics, Atomic physics, 010306 general physics, Excitation
Abstract

Elastic and inelastic scattering of 1435 MeV 17O ions on 208Pb, 120Sn, 90Zr and 60Ni have been measured. Hindrance in the excitation of the first 3− states is observed. Parameters of the isoscalar giant monopole and quadrupole resonances are obtained. The quadrupole resonance exhausts ∼ 55% of the energy-weighted sum rule while the observed monopole resonance corresponds to more than 100% of the sum rule. Strength is also observed at high excitation energy in all targets.

Published
1993

174. Editors' Preface

Author

Scott Pratt, Rene Bellwied, and Roy A. Lacey

Subjects
History, Series (mathematics), Library science, Computer Science Applications, Education
Published
2010

175. Hadronic dissipative effects on transverse dynamics at RHIC

Author

Tetsufumi Hirano, Roy A. Lacey, Ulrich Heinz, Dmitri E. Kharzeev, and Yasushi Nara

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, High Energy Physics::Phenomenology, Hadron, FOS: Physical sciences, Perfect fluid, Plasma, Phi meson, Resonance (particle physics), Nuclear Theory (nucl-th), Nuclear physics, Cascade, Nuclear Physics - Theory, Dissipative system, High Energy Physics::Experiment, Nuclear Experiment, Relativistic Heavy Ion Collider
Abstract

We simulate the dynamics of Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) with a hybrid model that treats the quark-gluon plasma macroscopically as an ideal fluid, but models the hadron resonance gas microscopically using a hadronic cascade. We find that much of the mass-ordering pattern for v_2(p_T) observed at RHIC is generated during the hadronic stage due to build-up of additional radial flow. We also find that the mass-ordering pattern is violated for phi meson due to small interaction cross section in the hadron resonance gas., Comment: 4 pages, 4 figures. To be published in the proceedings of Quark Matter 2008, Jaipur, India

Published
2008

176. Editors' Preface

Author

Wolfgang Bauer, Dmitri Kharzeev, Roy A. Lacey, Michael A. Lisa, and Sergey Panitkin

Subjects
Nuclear and High Energy Physics, General Physics and Astronomy
Published
2005

177. High-pT charged hadron suppression in Au+Au collisions at √sNN=200 GeV

Author

T. Ichihara, A. Litvinenko, M. A. Volkov, A. Isupov, F. K. Wohn, T. K. Ghosh, Matthew G. Reuter, T. L. Thomas, David D'Enterria, H. Tsuruoka, C. A. Ogilvie, S. Bathe, R. P. Pisani, V. Ladygin, M. Gonin, T. K. Hemmick, Kensuke Homma, Yasuo Miake, N. N. Ajitanand, Nikolay Tyurin, E. Melnikov, S. Afanasiev, X. He, Y. J. Kwon, Takahiro Nakamura, R. A. Soltz, Ryugo S. Hayano, M. E. Sadler, S. Chernichenko, H. Lim, A. Ster, L. Sanfratello, I. D. Ojha, Alexander Malakhov, V. Peresedov, B. Bassalleck, F. Mühlbacher, K. Kurita, S. Borenstein, L. Ewell, A. Durum, Y. Kuroki, W. Y. Jang, Y. Riabov, B. D. Fox, Kenta Shigaki, M. Sivertz, M. Grosse Perdekamp, D. S. Brown, Norio Saito, V. Bumazhnov, A. S. Nyanin, M. Issah, H. Masui, F. Messer, P. D. Barnes, A. Yanovich, N. Kamihara, S. Garpman, M. Heffner, E. Vznuzdaev, V. Baublis, V. Babintsev, Jen-Chieh Peng, S. S. Adler, G. S. Kyle, F. Matathias, David Olle Rickard Silvermyr, James Alexander, P. Tarján, J. Chiba, M. Sakai, W. C. Chang, T. Shiina, D. E. Fields, B. V. Jacak, G. Gogiberidze, Y. Jeong, R. Averbeck, A. Drees, Byung-Sik Hong, S. Sawada, A. Bazilevsky, J. D. Tepe, A. Franz, O. Dietzsch, V. S. Pantuev, H. A. Gustafsson, M. Harvey, Roy A. Lacey, Philippe Rosnet, S. N. White, Charles Maguire, S. Leckey, A. K. Purwar, G. C. Mishra, Alexandre Lebedev, E. J. Desmond, S. S. Kapoor, Dipanwita Dutta, Junji Tojo, J. B. Choi, D. M. Lee, Martin Purschke, Takao Sakaguchi, S. Butsyk, B. Khachaturov, Vladimir Samsonov, I. Otterlund, Sean A. Kelly, L. Aphecetche, R. E. Mischke, C. Zhang, C. Klein-Boesing, R. du Rietz, Josh Moss, K. Okada, S. P. Stoll, Julia Velkovska, M. Hibino, J. T. Mitchell, E. P. Hartouni, H. En'yo, P. Constantin, A. G. Hansen, Shingo Sakai, W. E. Sondheim, T. Matsumoto, M. Tamai, A. D. Frawley, J. Park, Vladislav Manko, M. D. Marx, Dong Jo Kim, G. Bunce, Osamu Jinnouchi, M. J. Leitch, E. Kistenev, D. Isenhower, H. W. Van Hecke, C. L. Woody, S. Y. Fung, Joakim Nystrand, J. L. Nagle, T. Chujo, S. H. Aronson, X. Camard, M. Rosati, M. Velkovsky, A. Kozlov, R. Seto, D. Jouan, G. R. Young, V. Kochetkov, A. Parmar, Senta Greene, M. Nara, W. Holzmann, John Hill, K. Oyama, Christine Angela Aidala, R. Amirikas, S. F. Pate, D. Kotchetkov, Viktor Riabov, S. Bhagavatula, A. A. Vinogradov, Henrik Tydesjö, Jiangyong Jia, Y. I. Makdisi, J. E. Frantz, Toru Sugitate, C. P. Singh, I. E. Yushmanov, I. V. Sourikova, H. Torii, Shih-Chang Lee, K. S. Sim, X. R. Wang, Y. Tanaka, Y. Goto, Alexander Milov, S. L. Fokin, K. N. Barish, P. Chand, E. O'Brien, O. Drapier, T. K. Shea, Alexei Khanzadeev, S. Batsouli, T. C. Awes, Wei Xie, V. Papavassiliou, Z. Fraenkel, R. K. Choudhury, A. Deshpande, N. Bruner, E. Stenlund, François Fleuret, M. J. Tannenbaum, M. Ono, L. Kochenda, K. Imai, D. P. Morrison, V. E. Semenov, V. V. Ikonnikov, Jun Kikuchi, H. Kobayashi, Jan Rak, W. Guryn, S. C. Johnson, Agneta Oskarsson, Y. J. Mao, M. J. Kweon, A. P.T. Palounek, R. Granier de Cassagnac, D. Bucher, Y. Berdnikov, H. J. Kim, S. Esumi, K. Ozawa, I. Tserruya, Y. Akiba, Yu. Efremenko, M. L. Brooks, V. Singh, Kazuhiro Tanaka, S. Nagamiya, L. Villatte, Klaus Johannes Reygers, G. B. Kim, D. Koehler, W. A. Zajc, J. S. Chai, Herve Borel, A. Denisov, V. Cianciolo, E. Kim, A. Hoover, Atsushi Taketani, V.A. Onuchin, P. L. McGaughey, Hirohiko Sato, S. K. Tuli, S. Belikov, K. S. Joo, J. M. Burward-Hoy, K. El Chenawi, M. R. Shaw, N. Grau, Jason Newby, A. Glenn, J. Murata, Minghui Liu, Kenneth Francis Read, L. Zolin, P. W. Stankus, Do-Won Kim, P. J. Kroon, Dong-Hun Kim, S. P. Sorensen, Peter M. Nilsson, Hideki Hamagaki, J. G. Lajoie, T. Hachiya, I. J. Choi, Hiroaki Ohnishi, J. Milan, G. David, C. H. Kuberg, H. Buesching, Xingguo Li, Y. Yang, B. M. Johnson, H. Delagrange, R. S. Towell, Yanwen Liu, M. Kopytine, S. Zhou, M. Chiu, Ajit Kumar Mohanty, T. A. Shibata, K. Kiyoyama, C. Y. Chi, B. K. Nandi, S. Kametani, T. Peitzmann, Saskia Mioduszewski, J. H. Kang, J. S. Haggerty, A. Romana, Yves Roland Schutz, German Martinez, J. M. Heuser, D. Pal, E. M. Takagui, B. A. Cole, J. Gosset, J. P. Sullivan, S. Yokkaichi, T. E. Miller, J. G. Boissevain, K. Katou, R. Santo, A. Enokizono, A. Kiyomichi, C. Pinkenburg, M. Stepanov, G. Roche, Y. Watanabe, A. Soldatov, K. Tanida, Alberto Baldisseri, C. L. Silva, T. Kohama, Masayasu Ishihara, Susumu Sato, M. Muniruzzaman, F. Staley, I. Ravinovich, F. Plasil, S. S. Ryu, R. Azmoun, D. Mukhopadhyay, Y. Cobigo, Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), PHENIX, Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and 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)

Subjects
Nuclear and High Energy Physics, Particle physics, quark-gluon plasma, Hadron, Nuclear Theory, pion production, FOS: Physical sciences, nuclei with mass number 190 to 219, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Spectral line, Nuclear physics, Pion, heavy ion-nucleus scattering, 0103 physical sciences, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, hadron production, 010308 nuclear & particles physics, Antiproton, Quark–gluon plasma, High Energy Physics::Experiment, Relativistic Heavy Ion Collider, Centrality
Abstract

The PHENIX experiment at RHIC has measured charged hadron yields at mid-rapidity over a wide range of transverse momentum (0.5 < p_T < 10 GeV/c) in Au+Au collisions at sqrt(s_NN)=200 GeV. The data are compared to pi^zero measurements from the same experiment. For both charged hadrons and neutral pions, the yields per nucleon-nucleon collision are significantly suppressed in central compared to peripheral and nucleon-nucleon collisions. The suppression sets in gradually and increases with increasing centrality of the collisions. Above 4-5 GeV/c in p_T, a constant and almost identical suppression of charged hadrons and pi^zeroes is observed. The p_T spectra are compared to published spectra from Au+Au at sqrt(s_NN)=130 in terms of x_t scaling. Central and peripheral pi^zero as well as peripheral charged spectra exhibit the same x_t scaling as observed in p+p data., 325 authors, 22 pages text, 18 figures, 6 tables, RevTeX 4. Minor revisions to address referee concerns during journal review. Now published in Physical Review C as a regular article. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are publicly available at http://www.phenix.bnl.gov/papers.html

Published
2004

178. Particle-particle coincidence measurements for1,2,3H andHe4in the reaction 480 MeVAg56

Author

Graham F. Peaslee, John M. Alexander, Louis C. Vaz, N. N. Ajitanand, D. Logan, Roy A. Lacey, Morton Kaplan, M. Kildir, D. J. Moses, and Michael S. Zisman

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Deuterium, Fission, Nuclear Theory, Hadron, Alpha particle, Inelastic scattering, Atomic physics, Nuclear Experiment, Nucleon, Charged particle
Abstract

Particle-particle coincidence measurements have been made between light charged particles (/sup 1,2,3/H and /sup 4/He) produced in the reaction (8.5 MeV/nucleon) /sup 56/Fe+/sup nat/Ag. This coincidence requirement emphasizes central collisions leading to evaporation residues. Average multiplicities are found to be approximately three alphas and approximately four protons per evaporation residue; these values imply that approximately (1/2 the initial excitation energy of about 211 MeV is evacuated from the evaporation residues by these particles. This fractional energy evacuation by charged particles is considerably larger than that found for the similar reaction (8.5 MeV/nucleon) /sup 40/Ar+/sup nat/Ag. In both reactions the effective emission barriers for /sup 1/H and /sup 4/He (as deduced from the energy spectra) are found to be significantly lower than corresponding empirical fusion barriers between cold nuclei. This is particularly surprising for emitter nuclei that survive fission.

Published
1989

179. Mechanisms for light charged particle emission in the reactions 247 and 337 MeVAr40+natAg

Author

Graham F. Peaslee, Morton Kaplan, Michael S. Zisman, Ludwik Kowalski, D. M. de Castro Rizzo, N. N. Ajitanand, G. La Rana, D. J. Moses, Roy A. Lacey, Paul DeYoung, W. E. Parker, M. Kildir, Louis C. Vaz, John M. Alexander, and D. Logan

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Thermalisation, Transition metal, Fission, Nuclear Theory, Multiplicity (mathematics), Atomic physics, Nuclear Experiment, Spectral line, Charged particle, Coincidence
Abstract

Light charged particles from the reactions 247 and 337 MeV $^{40}\mathrm{Ar}$${+}^{\mathrm{nat}}$Ag have been measured in singles and in coincidence with fission-like products. Most of the $^{1}\mathrm{H}$ and $^{4}\mathrm{He}$ in coincidence with fusion-fission and quasifission can be accounted for by evaporation from the composite nucleus or by the fragments. Multiplicities are determined for $^{1}\mathrm{H}$ and $^{4}\mathrm{He}$ in association with evaporation residues, fusion-fission, and quasifission. The probability for composite nucleus emission decreases with increasing spin zone of the emitter and gives a view of the role of emitter lifetime. The ratio of composite-nucleus multiplicities for quasifission/fusion-fission is about 1/2 ((1/4) for 337 MeV $^{40}\mathrm{Ar}$ (247 MeV $^{40}\mathrm{Ar}$) which implies a similar ratio for the lifetimes of the respective composite nuclei between thermalization and scission. Energy spectra and angular distributions of particles (in coincidence with fusion-fission and quasifission) are consistent with emission from a strongly distorted nuclear system en route toward scission. Prethermalization emission of $^{4}\mathrm{He}$ is observed at 10\ifmmode^\circ\else\textdegree\fi{} in comparable amounts for peripheral collisions (quasifission and fusion-fission) and for central collisions.

Published
1988

180. LARGE-ANGLE CORRELATIONS IN EVAPORATIVE PARTICLE EMISSION : SHAPE DISTORTION ? SURFACE EXPANSION ?

Author

John M. Alexander, D. Logan, D. J. Moses, G. La Rana, Louis C. Vaz, Paul DeYoung, Roy A. Lacey, N. N. Ajitanand, D. M. de Castro Rizzo, W. E. Parker, Graham F. Peaslee, and Morton Kaplan

Subjects
Nuclear reaction, Physics, Photon, Spins, Distortion, Nuclear Theory, General Engineering, Evaporation, Atomic physics, Deformation (engineering), Nuclear Experiment, Spectral line, Charged particle
Abstract

Evaporation-like emission of light particles (n, H, He...) has been observed for many nuclear reactions that populate composite nuclei with temperatures of up to ≤ 5 MeV and spins as high as ≤ 150h. The measured average energies for the light charged particles are often significantly lower than calculations for evaporation from spherical nuclei. Detailed calculations have not been reported for the role of deformation in evaporative emission patterns, and thus the interpretation of such data has been severely limited. In this paper we describe a method for making evaporation calculations for deformed nuclei, and we present results for several systems. The trends of the calculated results are compared to those for spherical emitters in order to get a feeling for those effects peculiar to the deformations. The patterns of calculated spectra and angular distributions encourage the notion that such studies can give valuable clues to the shapes and surface properties of these very hot nuclei. Comparisons are made to experimental data for 1H-4He and 4He-4He correlations in the reaction 337 MeV 40Ar + natAg. These comparisons point out some novel features of the nuclear surface.

Published
1986

181. Surprising properties of the nuclear stratosphere indicated by energy spectra and large-angle correlations between and or

Author

D. J. Moses, D. Logan, W. E. Parker, Graham F. Peaslee, Louis C. Vaz, D. M. de Castro Rizzo, P. A. DeYoung, G. La Rana, John M. Alexander, N. N. Ajitanand, Roy A. Lacey, Morton Kaplan, and L. Kowalski

Subjects
Physics, Nuclear and High Energy Physics, Proton emission, Atomic physics, Stratosphere, Energy (signal processing), Spectral line, Common emitter
Abstract

Angular and energy distributions are reported for 4 He in correlation with 1,2,3 H and 4 He in the reaction 337 MeV 40 Ar+ nat Ag. Comparisons are made to a statistical model that includes emitter. Energy spectra important barrier reductions compared to those for cold nuclei, ≈25%, 12%, 8% and 0 for 1 H, 4 He, 2 H and 3 H respectively. Emitter deformation alone cannot give an explanation. A transitory nuclear stratosphere is suggested with proton emission favored from its fringes of lowest density.

Published
1987

182. Sources of light-charged-particle emission in the reaction 480 MeVFe56+natAg

Author

Michael S. Zisman, D. Guerreau, John M. Alexander, M. Kildir, D. Logan, D. J. Moses, Roy A. Lacey, Morton Kaplan, Graham F. Peaslee, Louis C. Vaz, and N. N. Ajitanand

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Deuterium, Fission, Hadron, Elementary particle, Alpha particle, Atomic physics, Inelastic scattering, Charged particle
Abstract

Inclusive and exclusive measurements of light-charged particles (/sup 1,2,3/H,/sup 4/He) and heavy fragments have been made for the reaction 480 MeV /sup 56/Fe+/sup nat/Ag. The backward hemisphere emission of /sup 4/He and /sup 1/H in coincidence with a heavy fragment can be well described by evaporative emission from a combination of three sources: the detected fragment, the undetected fragment, and the composite system prior to scission. Multiplicities for each of these sources are determined for two coincident fragment groups: a fusion-fission-like group and a deeply-inelastic-reaction group. These multiplicities have also been studied at two angles for the trigger fragment (theta/sub TR/ = 26/sup 0/ and 50/sup 0/). For theta/sub TR/ = 26/sup 0/ the multiplicity of the light-charged particles (/sup 1/H or /sup 4/He) emitted from the composite nuclear system (i.e., prior to scission) is approx. =(2/3 for the fusion-fission-like fragments, compared to approx. =(1/3 for the deeply inelastic reactions. This decrease implies that the deeply inelastic reactions occur in approx. =(1/2 the time required for fission reactions. For the deeply inelastic reactions, these multiplicities change with trigger angle. This result also suggests that the lifetime of the composite system exerts some control on the extent of evaporative particle emission.more » Energy and angular distributions of the coincident light particles suggest extensive emission from a strongly deformed composite system, such as that of a system en route to scission. Low-energy /sup 4/He particles at forward angles, which cannot be attributed to evaporation, exhibit a dependence on the angle with respect to the scission axis. This result is attributed to emission that occurs very near to the instant of scission.« less

Published
1988

183. GANES: A computer program for the simulation of laboratory spectra of evaporative light particles in heavy ion reactions

Author

N. N. Ajitanand, Graham F. Peaslee, E. Duek, Roy A. Lacey, and John M. Alexander

Subjects
Physics, Nuclear and High Energy Physics, Photon, Fission, Monte Carlo method, Inelastic collision, Atomic physics, Moment of inertia, Nuclear Experiment, Breakup, Instrumentation, Spectral line, Spin-½
Abstract

A computer program called GANES has been written to simulate the evaporation of light particles in heavy ion reactions. The program uses the very efficient “weighted Monte Carlo” method. GANES has been designed to treat two-body breakup reactions such as fusion fission and three-body breakup reactions such as sequential fission (of a heavy product) after a primary inelastic collision. GANES calculates energy spectra for light particles evaporated from a composite nucleus before scission, and also from fully accelerated fragments after scission. Mass, energy and angular distributions of the heavy fragments are taken into account. Energy spectra (inclusive and exclusive) of the evaporated particles are calculated by a semiclassical formulation for detectors of finite size at a number of laboratory directions, both in and out of the reaction plane. Detector thresholds and various coincidence gates are also considered. GANES has been used to identify the emission sources of evaporative particles and to determine their multiplicities. It has also been used to study the thermodynamic properties of the emitters, such as effective emission barrier, temperature, moment of inertia and root-mean-square spin.

Published
1986

184. Large-angle correlations betweenHe4and1,2,3H orHe4in the reactions 247 and 337 MeVAr40+natAg: Unexpected properties of the nuclear stratosphere

Author

G. La Rana, Graham F. Peaslee, Roy A. Lacey, John M. Alexander, D. J. Moses, D. Logan, D. M. de Castro Rizzo, N. N. Ajitanand, Ludwik Kowalski, Morton Kaplan, Louis C. Vaz, M. Kildir, Paul DeYoung, Michael S. Zisman, and W. E. Parker

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Helium-4, Hadron, Atomic physics, Coupling (probability), Nucleon, Isotopes of helium, Charged particle, Energy (signal processing)
Abstract

We have measured coincidences between $^{4}\mathrm{He}$ and $^{1}$,2,3H or a second $^{4}\mathrm{He}$ (large-angle correlations) in the reactions 247 and 337 MeV $^{40}$Ar${+}^{\mathrm{nat}}$Ag. These coincidences are dominated by reactions leading to evaporation residues with spins of about 0--70\ensuremath{\Elzxh}. Large values of the angle-integrated double and triple coincidence cross sections indicate that many particle evaporation chains involve 2 or 3 protons and/or 2 or 3 alphas. The angular and energy distributions are well described by an evaporation model with Hauser-Feshbach coupling. However, one must employ effective evaporation barriers for $^{1}\mathrm{H}$ and $^{4}\mathrm{He}$ that are strongly reduced compared to empirical fusion barriers. The barrier reduction required for $^{2}\mathrm{H}$ is rather small, and for $^{3}\mathrm{H}$ no barrier reduction is needed. Evaporation calculations that include emitter deformation do not give a satisfactory explanation for these results. We suggest a new aspect of composite nucleus excitation and evaporation-like decay. A hot, very diffuse nuclear surface may be formed that promotes evaporative decay prior to its relaxation. The low barriers for $^{1}\mathrm{H}$ and $^{4}\mathrm{He}$ reflect the radial extent of this transitory, diffuse surface.

Published
1988

185. Need for new physics in statistical models of nuclear de-excitation

Author

D. Logan, Welberry Rj, John M. Alexander, D. J. Moses, W. E. Parker, La Rana G, Roy A. Lacey, and Morton Kaplan

Subjects
Nuclear physics, Physics, Nuclear reaction, Nuclear and High Energy Physics, Helium-4, Mathematical model, Spins, Moment of inertia, Atomic physics, Isotopes of helium, Excitation, Spectral line
Abstract

We have measured energy spectra and angular distributions of /sup 1/H and /sup 4/He from 190--MeV /sup 40/Ar+ /sup 27/Al reactions. Comparisons with statistical model calculations show that evaporation from spherical nuclei cannot account for both the energy spectra and angular distributions, using entrance channel spins and evaporation barriers derived from fusion data. Alterations are required in both the emission barriers and the moments of inertia. Extensive nuclear deformation could explain the /sup 4/He data but discrepancies remain with the /sup 1/H spectra, suggesting that additional effects are needed in the models.

Published
1987

186. Light charged particle emission in 485 MeV 56Fe + 197Au reactions: Correlations with heavy fragments and relationships to spin and lifetime

Author

D. Logan, Michael S. Zisman, N. N. Ajitanand, M. Kildir, D. J. Moses, G. La Rana, Graham F. Peaslee, Morton Kaplan, Roy A. Lacey, Louis C. Vaz, John M. Alexander, and W. E. Parker

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Fission, Excited state, Thermal equilibration, Equal probability, Beam direction, Multiplicity (mathematics), Atomic physics, Nuclear Experiment, Charged particle
Abstract

Emission of 4 He and 1 H has been studied in reactions of 485 MeV 56 Fe + 197 Au, using low-threshold detector arrays for light charged particles, and two heavy-fragment trigger detectors placed at symmetrically opposite angles with respect to the beam direction. The light charged particles were measured both in singles and in coincidence with heavy products of deeply inelastic and fission reactions detected near the grazing angle. Statistical model analyses of the data show that most of the 4 He/ 1 H intensity is due to evaporation from energy equilibrated emitters both in deeply inelastic and fission reactions. In deeply inelastic reactions, the observed 4 He/ 1 H emission can be attributed to evaporation from the post-scission reactant-like products, while in fusion-like fission reactions evaporation from pre- and post-scission sources are observed in comparable amounts. Angle-integrated multiplicities for 4 He and 1 H are deduced for each source of emission, and are compared with results from similar systems. The experimental 4 He/ 1 H multiplicity ratios indicate roughly equal probability for 4 He and 1 H evaporation from a given excited source. The observation of pre-scission 4 He/ 1 H in fusion-like fission reactions supports the notion that thermal equilibration and subsequent particle evaporation proceed more rapidly than the collective motions that drive the system toward fission. Conversely, the lack of appreciable 4 He/ 1 H emission from pre-scission sources in deeply inelastic reactions implies that the interaction times are short compared to the time required for particle evaporation.

Published
1987

187. Multiplicities for evaporative4He emission in heavy ion reactions: Relationships to spin and lifetime expectancy of the composite nucleus

Author

Graham F. Peaslee, Michael S. Zisman, Morton Kaplan, E. Duek, D. Logan, D. J. Moses, John M. Alexander, H. Delagrange, Ludwik Kowalski, Louis C. Vaz, D. Ø. Eriksen, Roy A. Lacey, N. N. Ajitanand, M. Kildir, D. Guerreau, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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 Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear and High Energy Physics, Spins, 010308 nuclear & particles physics, Nuclear Theory, Composite number, Evaporation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Coincidence, Spectral line, medicine.anatomical_structure, 0103 physical sciences, medicine, Nuclear fusion, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleus, Spin-½
Abstract

Multiplicities are compared for4He evaporation in reactions of40Ar and56Fe projectiles (8.5 MeV/u) with withnatAg and238U targets. Coincidence requirements involving fusion-fission and projectile-like fragments have been used to select separate entrance-channel spin zones. Evaporation-like4He emission from the composite nuclei is shown to be large for mean spins ≦100ℏ, and to decrease dramatically with increasing spin. Coincidence measurements between two4He particles have also been studied for40Ar+natAg. This requirement is shown to select reactions that lead to evaporation residues and therefore to a zone of relatively low spin. The shapes of the4He spectra provide an interesting probe of the mechanism and also of the thermodynamic properties of hot nuclei.

Published
1984

188. Clues to the shapes of very hot nuclei: Calculated patterns for evaporative emission from deformed nuclei

Author

Louis C. Vaz, Roy A. Lacey, N. N. Ajitanand, D. J. Moses, Graham F. Peaslee, Morton Kaplan, D. M. de Castro Rizzo, John M. Alexander, and G. La Rana

Subjects
Physics, Baryon, Nuclear reaction, Nuclear and High Energy Physics, Semi-empirical mass formula, Nuclear Theory, Neutron, Fermion, Atomic physics, Nuclear Experiment, Nucleon, Charged particle, Spectral line
Abstract

Evaporation-like emission of light particles (n, H, He, . . .) has been observed for many nuclear reactions that populate composite nuclei with temperatures of up to roughly-equal5 MeV and spins as high as roughly-equal150h-dash-bar. The measured average energies for the light charged particles are often significantly lower than calculations for evaporation from spherical nuclei. Detailed calculations have not been reported for the role of deformation in evaporative emission patterns, and thus the interpretation of such data has been severely limited. In this paper we describe a method for making evaporation calculations for deformed nuclei, and we present results for several systems with temperatures of 2--5 MeV. The trends of the calculated results are compared to those for spherical emitters in order to get a feeling for those effects peculiar to the deformations. The patterns of calculated spectra and angular distributions encourage the notion that such studies can give valuable clues to the shapes of these very hot nuclei.

Published
1986

189. Hadronic transport model with a phase transition

Author

Roy A. Lacey, Pawel Danielewicz, and Pol Bernard Gossiaux

Subjects
Excitation function, Quantum phase transition, Physics, Equation of state, Phase transition, Nuclear Theory, Condensed matter physics, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Degrees of freedom (physics and chemistry), FOS: Physical sciences, Observable, Plasma, Nuclear matter, Nuclear Theory (nucl-th), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

We specify a tractable transport model with thermodynamic properties close to those expected for the strongly interacting matter. In particular, at high temperatures, the matter undergoes a phase transition, such as to the quark-gluon plasma, with a drop in masses of elementary excitations and a rapid increase in the number of degrees of freedom. We show that a softening of the equation of state such as associated with the transition to quark-gluon plasma should be observable in the elliptic-flow excitation function from heavy-ion reactions., Comment: Talk given at the Workshop on Nuclear Matter in Different Phases and Transitions, Les Houches, March 31 - April 10, 1998; 16 pages, 10 Postscript figures, LateX requires crkpab.sty, graphicx.sty, and amssymb.sty

190. First results from RHIC-PHENIX

Author

V. S. Pantuev, R. A. Soltz, Y. Nakada, J. Kikuchi, Y. Kwon, M. Grosse Perdekamp, H. Wang, A. Kiyomichi, Junji Tojo, P. Pitukhin, T. A. Carey, Shunji Nishimura, T. L. Thomas, O. Dietzsch, V. Kochetkov, W. W. Kinnison, M. J. Leitch, E. Taniguchi, Dipanwita Dutta, David Olle Rickard Silvermyr, K. S. Sim, M. Sugioka, M. D. Marx, Julia Velkovska, S. Nagamiya, J. S. Haggerty, C. Witzig, Ryugo S. Hayano, S. T. Belyaev, S. Markacs, Y. Riabov, H. Tsuruoka, Alexei Khanzadeev, H. D. Sato, Kenta Shigaki, S-Y Fung, L. Kochenda, T. Matsumoto, M. A. Volkov, D. J. Lim, Sean A. Kelly, M. Rosati, A. S. Nyanin, M. Suzuki, M. Velkovsky, J. Chiba, V. Bumazhnov, P. W. Stankus, M. Pollack, E. Stenlund, E. P. Hartouni, S. Esumi, M. Messer, M. Chiu, A. A. Vinogradov, Henrik Tydesjö, A. Franz, Terry C Awes, G. C. Mishra, Agneta Oskarsson, B. V. Dinesh, A. Kozlov, W. A. Zajc, C. Velissaris, G. R. Young, R. Seto, I. Ravinovich, C. A. Ogilvie, T. K. Hemmick, Y. Berdnikov, Martin Purschke, N. N. Ajitanand, T. Peitzmann, Saskia Mioduszewski, Z. Sun, J. P. Sullivan, J. Simon-Gilio, James Alexander, Jiangyong Jia, Y. Goto, Yasuo Miake, V. Cianciolo, N. Starinsky, Lennart Osterman, C. L. Woody, Senta Greene, Kazuhiro Tanaka, Sergey Fokin, W. C. Chang, F. Plasil, Zhongfan Liu, Roy A. Lacey, Klaus Johannes Reygers, B. R. Schlei, C. P. Singh, S. F. Pate, F. G. Bellaiche, Minghui Liu, B. M. Johnson, Takao Sakaguchi, S. K. Mark, C. Klein-Boesing, Juergen Thomas, A. L. Godoi, S. Bathe, X. Liu, S. Yokkaichi, X. He, S. K. Tuli, Hyun-Chul Kim, Kenichi Imai, A. Hoover, J. Murata, B. K. Nandi, A. D. Frawley, Yves Roland Schutz, G. S. Kyle, C. Pinkenburg, S. S. Adler, M. Ishihara, N. Bruner, E. Vznuzdaev, V. Baublis, D. J. Kim, Hideki Hamagaki, H. A. Gustafsson, S. H. Aronson, S. Butsyk, E. O'Brien, P. Steinberg, Vladimir Samsonov, David D'Enterria, J. M. Heuser, S. K. Gupta, R. P. Pisani, E. M. Takagui, W. Y. Jang, T. Shiina, I. Shein, R. S. Towell, T-A Shibata, G. David, Y. I. Makdisi, T. K. Shea, L. L. Chavez, R. Averbeck, Byung-Sik Hong, Z. Fraenkel, A. A. Tsvetkov, Athanasios Petridis, Nikolay Tyurin, I. Otterlund, A. Bazilevsky, S. S. Ryu, Y. Akiba, A. A. Rose, Alexandre Lebedev, J. H. Thomas, F. Matathias, M. Kann, Kensuke Homma, E. Melnikov, S. Chernichenko, Wei Xie, J. Barrette, German Martinez, A. Deshpande, J. T. Mitchell, S. N. White, L. Paffrath, B. Bassalleck, F. Mühlbacher, Viktor Riabov, Kenneth Francis Read, Zhen Zhang, S. C. Johnson, Y. J. Mao, S. Klinksiek, Charles Maguire, N. Hayashi, A. Drees, M. J. Kweon, H. Hara, J. L. Nagle, H. W. Van Hecke, W. Guryn, Y. Sumi, Josh Moss, M. Tamai, D. M. Lee, L. Ewell, S. Garpman, R. E. Mischke, D. S. Ho, C. Y. Chi, A. Durum, K. N. Barish, Y. G. Kim, M. S. Chung, M. J. Bennett, A. Denisov, E. Kistenev, P. Chung, Mikhail Ippolitov, M. Ono, S. Kametani, S. Sawada, I. G. Sibiriak, D. S. Brown, S. Botelho, S. S. Kapoor, M. J. Tannenbaum, H. Torii, Y. Watanabe, M. Merschmeier, Yasushi Nagasaka, V. Papavassiliou, Atsushi Taketani, D. Bucher, M. L. Brooks, S. Y. Kim, D. E. Fields, T. Ushiroda, A. Masaike, B. V. Jacak, Vladislav Manko, Brian Cole, Y. Tanaka, A K Mohanty, V.A. Onuchin, S. Belikov, G. Bunce, A. G. Hansen, H. Delagrange, A. Soldatov, T. Ferdousi, T. Chujo, John Hill, K. Oyama, J. Chang, Norio Saito, T. C. Sangster, Toru Sugitate, J.R. Mahon, K. El Chenawi, Z. Li, Yoshio Arai, J. Lauret, T. Ichihara, F. K. Wohn, Aya Sakaguchi, T. Kohama, K. Yagi, S. Zhou, T. K. Ghosh, I. D. Ojha, W. Tian, Susumu Sato, R. K. Choudhury, Ju Hwan Kang, M. Muniruzzaman, P. D. Barnes, T. E. Miller, Laurent Bernard Aphecetche, R. Santo, K. Pope, A. Glenn, Hiroyuki Sako, B. Khachaturov, D. Kochetkov, Alexander Milov, D. P. Morrison, V. E. Semenov, T. Christ, I. Tserruya, Yu. Efremenko, V. Singh, D. Koehler, Joakim Nystrand, K. Ebisu, S. P. Stoll, P. Chand, Y. H. Shin, Tai Sakuma, P. L. McGaughey, P. J. Kroon, J. M. Burward-Hoy, A. Ster, K. S. Joo, F. Messer, Paul Nilsson, An.A. Vorobyov, K. Adcox, S. P. Sorensen, J. G. Lajoie, H. En'yo, K. Kurita, M. Sivertz, Hiroaki Ohnishi, L. Nikkinen, H. Buesching, Xingguo Li, Jason Newby, E. J. Desmond, A. P.T. Palounek, and I. E. Yushmanov

Subjects
Physics, Quantum chromodynamics, Particle physics, Large Hadron Collider, Calorimeter (particle physics), Physics::Instrumentation and Detectors, General Physics and Astronomy, Particle identification, Charged particle, Nuclear physics, Quark–gluon plasma, High Energy Physics::Experiment, Nuclear Experiment, Relativistic Heavy Ion Collider, Glauber
Abstract

The PHENIX experiment consists of a large detector system located at the newly commissioned relativistic heavy ion collider (RHIC) at the Brookhaven National Laboratory. The primary goal of the PHENIX experiment is to look for signatures of the QCD prediction of a deconfined high-energy-density phase of nuclear matter quark gluon plasma. PHENIX started data taking for Au+Au collisions at √sNN=130 GeV in June 2000. The signals from the beam-beam counter (BBC) and zero degree calorimeter (ZDC) are used to determine the centrality of the collision. A Glauber model reproduces the ZDC spectrum reasonably well to determine the participants in a collision. Charged particle multiplicity distribution from the first PHENIX paper is compared with the other RHIC experiment and the CERN, SPS results. Transverse momentum of photons are measured in the electro-magnetic calorimeter (EMCal) and preliminary results are presented. Particle identification is made by a time of flight (TOF) detector and the results show clear separation of the charged hadrons from each other.

192. Influence of finite volume and magnetic field effects on the QCD phase diagram.

Author

Niseem Magdy, M Csanád, and Roy A Lacey

Subjects
FINITE volume method, MAGNETIC field effects, QUANTUM chromodynamics, PHASE diagrams, BARYONS
Abstract

The 2 + 1 SU(3) Polyakov linear sigma model is used to investigate the respective influence of a finite volume and a magnetic field on the quark-hadron phase boundary in the plane of baryon chemical potential () versus temperature (T) of the quantum chromodynamics (QCD) phase diagram. The calculated results indicate sizable shifts of the quark-hadron phase boundary to lower values of for increasing magnetic field strength, and an opposite shift to higher values of for decreasing system volume. Such shifts could have important implications for the extraction of the thermodynamic properties of the QCD phase diagram from heavy ion data. [ABSTRACT FROM AUTHOR]

Published
2017
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193. Acoustic scaling of anisotropic flow in shape-engineered events: implications for extraction of the specific shear viscosity of the quark gluon plasma.

Author

D Reynolds, N N Ajitanand, J M Alexander, Yi Gu, A Mwai, Roy A Lacey, A Taranenko, and Fu-Hu Liu

Subjects
SCALING laws (Nuclear physics), QUARK-gluon plasma, VISCOSITY, EXTRACTION techniques, COLLISIONS (Nuclear physics)
Abstract

It is shown that the acoustic scaling patterns of anisotropic flow for different event shapes at a fixed collision centrality (shape-engineered events), provide robust constraints for the event-by-event fluctuations in the initial-state density distribution from ultrarelativistic heavy ion collisions. The empirical scaling parameters also provide a dual-path method for extracting the specific shear viscosity of the quark-gluon plasma (QGP) produced in these collisions. A calibration of these scaling parameters via detailed viscous hydrodynamical model calculations, gives estimates for the plasma produced in collisions of Au + Au () and Pb + Pb (). The estimates are insensitive to the initial-state geometry models considered. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
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194. Multifragmentation and possible experimental signatures of a liquid-gas phase transition of nuclear matter

Author

Tamain, B., Guesnon, Sandrine, Roy A Lacey, Augusto O Macchiavelli, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
2006

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