Comparison of nonequilibrium processes in p+Ni and p+Au collisions at GeV energies
A. Budzanowski, M. Fidelus, D. Filges, F. Goldenbaum, H. Hodde, L. Jarczyk, B. Kamys, M. Kistryn, St. Kistryn, St. Kliczewski, A. Kowalczyk, E. Kozik, P. Kuless… 展开作者
A. Budzanowski, M. Fidelus, D. Filges, F. Goldenbaum, H. Hodde, L. Jarczyk, B. Kamys, M. Kistryn, St. Kistryn, St. Kliczewski, A. Kowalczyk, E. Kozik, P. Kulessa, H. Machner, A. Magiera, B. Piskor-Ignatowicz, K. Pysz, Z. Rudy, R. Siudak, M. Wojciechowski
The energy and angular dependence of double differential cross sections d2sigma/dOmega dE were measured for p, d, t, 3,4,6He, 6,7,8Li, 7,9,10Be, 10,11B, and C produced in collisions of 1.2, 1.9, and 2.5 GeV protons with a Ni target. The shape of the spectra and angular distributions does almost not change whereas the absolute value of the cross sections increases by a factor about 1.7 for all ejectiles in this beam energy range. It was found that energy and angular dependencies of the cross sections cannot be reproduced by the microscopic model of intranuclear cascade with coalescence of nucleons and the statistical model for evaporation of particles from excited, equilibrated residual nuclei. The inclusion of nonequilibrium processes, described by a phenomenological model of the emission from fast and hot moving sources, resulting from break-up of the target nucleus by impinging proton, leads to very good reproduction of data. Cross sections of these processes are quite large, exhausting approximately half of the total production cross sections. Due to good reproduction of energy and angular dependencies of d2sigma/dOmega dE by model calculation it was possible to determine total production cross sections for all studied ejectiles. Results obtained in this work point to the analogous reaction mechanism for proton induced reactions on Ni target as that observed previously for Au target in the same beam energy range.
Beam asymmetry for pi+ and pi0 photoproduction on the proton for photon energies from 1.102 to 1.862 GeV
用CEBAF大接收谱仪（CLAS）和能量为1.102 - 1.862 GeV的线偏振光子束测量了γ p -> p π 0和γ p -> n π +反应的束流不对称性。本文介绍了一种从实验数据中提取光束非对称性的傅里叶矩技术。这里报道的结果具有更高的精度和更精细的能量分辨率比以前的测量。我们的两个π介子反应的数据似乎有利于SAID和Bonn-Gatchina散射分析的老美因茨MAID预测。在将目前的光束不对称性集合并入世界数据库之后，用SAID分析进行的探索性拟合表明，与先前拟合相比的最大变化是针对Delta（1700）3/2-和Delta（1905）5/2+状态的性质。
Mean-field update in the JAM microscopic model: Mean-field effects on collective flow in high-energy heavy-ion collisions at $\sqrt{s_{NN}}=2-20$ GeV energies
