Isotopic cross-sections in proton induced spallation reactions based on the Bayesian neural network method *
Chun-Wang Ma, Dan Peng, Hui-Ling Wei, Zhong-Ming Niu, Yu-Ting Wang, and R. Wada
The Bayesian neural network (BNN) method is proposed to predict the isotopic cross-sections in proton induced spallation reactions. Learning from more than 4000 data sets of isotopic cross-sections from 19 experimental measurements and 5 theoretical predictions with the SPACS parametrization, in which the mass of the spallation system ranges from 36 to 238, and the incident energy from 200 MeV/u to 1500 MeV/u, it is demonstrated that the BNN method can provide good predictions of the residue fragment cross-sections in spallation reactions.The Bayesian neural network (BNN) method is proposed to predict the isotopic cross-sections in proton induced spallation reactions. Learning from more than 4000 data sets of isotopic cross-sections from 19 experimental measurements and 5 theoretical predictions with the SPACS parametrization, in which the mass of the spallation system ranges from 36 to 238, and the incident energy from 200 MeV/u to 1500 MeV/u, it is demonstrated that the BNN method can provide good predictions of the residue fragment cross-sections in spallation reactions.
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014104
Skyrmion stability at finite isospin chemical potential and temperature *
Wen-Li Yuan, Zhen-Ni Xu, Jin-Li Zhang, and Hong-Shi Zong
The skyrmion stability at finite isospin chemical potential is studied using the Skyrme Lagrangian with a finite pion mass . A critical value , above which a stable soliton does not exist, is found. We also explore some properties of the skyrmion as function of , i.e., the isoscalar rms radius and the isoscalar magnetic rms radius. Finally, considering the finite temperature effect on the skyrmion mass, we obtain a critical temperature , using the profile function of the skyrmion, above which the skyrmion mass does not have a minimum, which can be interpreted as the occurrence of the deconfinement phase transition.The skyrmion stability at finite isospin chemical potential
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014103
Antiproton production in heavy-ion collisions at subthreshold energies *
Zhao-Qing Feng
Within the framework of the Lanzhou quantum molecular dynamics model, the deep subthreshold antiproton production in heavy-ion collisions has been investigated thoroughly. The elastic scattering, annihilation and charge exchange reactions associated with antiproton channels are implemented in the model. The attractive antiproton potential extracted from the G-parity transformation of nucleon selfenergies reduces the threshold energies in meson-baryon and baryon-baryon collisions, and consequently enhances the antiproton yields to some extent. The calculated invariant spectra are consistent with the available experimental data. The primordial antiproton yields increase with the mass number of the colliding system. However, annihilation reactions reduce the antiproton production which becomes independent of the colliding partners. Anti-flow phenomena of antiprotons correlated with the mean field potential and annihilation mechanism is found by comparing them with the proton flows. Possible experiments at the high-intensity heavy-ion accelerator facility (HIAF) in China are discussed.Within the framework of the Lanzhou quantum molecular dynamics model, the deep subthreshold antiproton production in heavy-ion collisions has been investigated thoroughly. The elastic scattering, annihilation and charge exchange reactions associated with antiproton channels are implemented in the model. The attractive antiproton potential extracted from the G-parity transformation of nucleon selfenergies reduces the threshold energies in meson-baryon and baryon-baryon collisions, and consequently enhances the antiproton yields to some extent. The calculated invariant spectra are consistent with the available experimental data. The primordial antiproton yields increase with the mass number of the colliding system. However, annihilation reactions reduce the antiproton production which becomes independent of the colliding partners. Anti-flow phenomena of antiprotons correlated with the mean field potential and annihilation mechanism is found by comparing them with the proton flows. Possible experiments at the high-intensity heavy-ion accelerator facility (HIAF) in China are discussed.
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014102
Constituent quark number scaling from strange hadron spectra in pp collisions at TeV *
Jian-Wei Zhang, Hai-Hong Li, Feng-Lan Shao, and Jun Song
We show that the spectra of and at midrapidity in the inelastic events in collisions at 13 TeV exhibit a constituent quark number scaling property, which is a clear signal of quark combination mechanism at hadronization. We use a quark combination model with equal velocity combination approximation to systematically study the production of identified hadrons in collisions at = 13 TeV. The midrapidity spectra for protons, , , , and in the inelastic events are simultaneously fitted by the model. The multiplicity dependence of the yields of these hadrons are also well understood. The strong dependence of the ratio is well explained by the model, which further suggests that the production of two hadrons with similar masses is determined by their quark content at hadronization. The spectra of strange hadrons at midrapidity in different multiplicity classes in collisions at 13 TeV are predicted for further tests of the model. The midrapidity spectra of soft ( GeV/c) strange quarks and up/down quarks at hadronization in collisions at 13 TeV are extracted.We show that the
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014101
Measurement of the differential cross sections and angle-integrated cross sections of the 6Li(n, t)4He reaction from 1.0 eV to 3.0 MeV at the CSNS Back-n white neutron source *
Huaiyong Bai, Ruirui Fan, Haoyu Jiang, Zengqi Cui, Yiwei Hu, Guohui Zhang, Zhenpeng Chen, Wei Jiang, Han Yi, Jingyu Tang, Liang Zhou, Qi An, Jie Bao, Ping Cao, Qiping Chen, Yonghao Chen, Pinjing Cheng, Changqing Feng, Minhao Gu, Fengqin Guo, Changcai Han, Zijie Han, Guozhu He, Yongcheng He, Yuefeng He, Hanxiong Huang, Weiling Huang, Xiru Huang, Xiaolu Ji, Xuyang Ji, Hantao Jing, Ling Kang, Mingtao Kang, Bo Li, Lun Li, Qiang Li, Xiao Li, Yang Li, Yang Li, Rong Liu, Shubin Liu, Xingyan Liu, Guangyuan Luan, Yinglin Ma, Changjun Ning, Binbin Qi, Jie Ren, Xichao Ruan, Zhaohui Song, Hong Sun, Xiaoyang Sun, Zhijia Sun, Zhixin Tan, Hongqing Tang, Pengcheng Wang, Qi Wang, Taofeng Wang, Yanfeng Wang, Zhaohui Wang, Zheng Wang, Jie Wen, Zhongwei Wen, Qingbiao Wu, Xiaoguang Wu, Xuan Wu, Likun Xie, Yiwei Yang, Li Yu, Tao Yu, Yongji Yu, Jing Zhang, Linhao Zhang, Liying Zhang, Qingmin Zhang, Qiwei Zhang, Xianpeng Zhang, Yuliang Zhang, Zhiyong Zhang, Yingtan Zhao, Zuying Zhou, Danyang Zhu, Kejun Zhu, and Peng Zhu
The 6Li(n, t)4He reaction was measured as the first experiment involving neutron-induced charged particle emission reactions at the CSNS (China Spallation Neutron Source) Back-n white neutron source. The differential cross-sections of the 6Li(n,t)4He reaction at 15 detection angles ranging from 19.2° to 160.8° are obtained from 1.0 eV to 3.0 MeV at 80 neutron energy points; for 50 energy points below 0.1 MeV they are reported for the first time. The results indicate that the anisotropy of the emitted tritium is noticeable above En = 100 eV. The angle-integrated cross-sections are also obtained. The present differential cross-sections agree in general with the previous evaluations, but there are some differences in the details. More importantly, the present results indicate that the cross-sections of the 6Li(n, t)4He reaction might be overestimated by most evaluations in the 0.5 - 3.0 MeV region, although they are recommended as standards below 1.0 MeV.The 6Li(n, t)4He reaction was measured as the first experiment involving neutron-induced charged particle emission reactions at the CSNS (China Spallation Neutron Source) Back-n white neutron source. The differential cross-sections of the 6Li(n,t)4He reaction at 15 detection angles ranging from 19.2° to 160.8° are obtained from 1.0 eV to 3.0 MeV at 80 neutron energy points; for 50 energy points below 0.1 MeV they are reported for the first time. The results indicate that the anisotropy of the emitted tritium is noticeable above En = 100 eV. The angle-integrated cross-sections are also obtained. The present differential cross-sections agree in general with the previous evaluations, but there are some differences in the details. More importantly, the present results indicate that the cross-sections of the 6Li(n, t)4He reaction might be overestimated by most evaluations in the 0.5 - 3.0 MeV region, although they are recommended as standards below 1.0 MeV.
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014003
Search for QCD critical point by transverse velocity dependence of anti-deuteron to deuteron ratio *
Ning Yu, Dingwei Zhang, and Xiaofeng Luo
We propose the transverse velocity ( ) dependence of the anti-deuteron to deuteron ratio as a new observable to search for the QCD critical point in heavy-ion collisions. The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is known as the focusing effect. To quantify this effect, we employ the thermal and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near the critical point. We found that the focusing effect can lead to anomalous dependence on , and ratios. We examined the dependence of and ratios of central Au+Au collisions at 7.7 to 200 GeV measured by the STAR experiment at RHIC. Surprisingly, we only observe a negative slope in dependence of ratio at 19.6 GeV, which indicates the trajectory evolution has passed through the critical region. In the future, we could constrain the location of the critical point and/or width of the critical region by conducting precise measurements on the dependence of the ratio at different energies and rapidity.We propose the transverse velocity (
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014002
Deformed dispersion relation constraint with hydrogen atom 1S-2S transition *
Jin Pu, Guo-Ping Li, Qing-Quan Jiang, and Xiao-Tao Zu
We use the latest results of the ultra-high accuracy 1S-2S transition experiments in the hydrogen atom to constrain the forms of the deformed dispersion relation in the non-relativistic limit. For the leading correction of the non-relativistic limit, the experiment sets a limit at an order of magnitude for the desired Planck-scale level, thereby providing another example of the Planck-scale sensitivity in the study of the dispersion relation in controlled laboratory experiments. For the next-to-leading term, the bound is two orders of magnitude away from the Planck scale, however it still amounts to the best limit, in contrast to the previously obtained bound in the non-relativistic limit from the cold-atom-recoil experiments.We use the latest results of the ultra-high accuracy 1S-2S transition experiments in the hydrogen atom to constrain the forms of the deformed dispersion relation in the non-relativistic limit. For the leading correction of the non-relativistic limit, the experiment sets a limit at an order of magnitude for the desired Planck-scale level, thereby providing another example of the Planck-scale sensitivity in the study of the dispersion relation in controlled laboratory experiments. For the next-to-leading term, the bound is two orders of magnitude away from the Planck scale, however it still amounts to the best limit, in contrast to the previously obtained bound in the non-relativistic limit from the cold-atom-recoil experiments.
- Jan. 01, 1900
- Chinese Physics C
- Vol. 44, Issue 1, (2020)
- DOI：10.1088/1674-1137/44/1/014001
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