Excitation functions have been measured for different projectile-like fragments produced in ^27Al（^19F, x ）y reactions at incident energies from 110. 25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctu...Excitation functions have been measured for different projectile-like fragments produced in ^27Al（^19F, x ）y reactions at incident energies from 110. 25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctuations of the excitation functions are observed. The cross-correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle θcm have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion collision of ^27Al（^19F, x）y.展开更多
Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,prot...Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,proton emission provied a dominant contribution to neutralize the system N/Z in the decay process of the hot nuclei.The emission of hydrogen isotopes with high energies is much enhanced in the ^(112)Sn system.The original temperature of the hot nuclei in the ^(40)Ar+^(112)Sn reaction is 5.8±0.3 MeV,about 0.7 MeV higher than 5.1±0.3 MeV as in the ^(40)Ar+^(124)Sn reaction.展开更多
Measurements of the total reaction cross section for^(12-16)C,^(14-17)N and^(16-18)O on carbon target at intermediate energies were performed on RIBLL of HIRFL.A larger enhancement ofσR for^(15)C was observed than th...Measurements of the total reaction cross section for^(12-16)C,^(14-17)N and^(16-18)O on carbon target at intermediate energies were performed on RIBLL of HIRFL.A larger enhancement ofσR for^(15)C was observed than that for its neighbors.The analysis of these data indicates possible existence of an anomalous nuclear structure in^(15)C.A new quantity was suggested as the criterion to distinguish anomalous structure nuclei from normal nuclei.展开更多
Correlation measurements of neutrons and fragments have been performed in a reaction of 33.4MeV/u ^(17)N on a ^(9)Be target.Energy spectra of n and nitrogen fragments were obtained at different angles.Based on the nuc...Correlation measurements of neutrons and fragments have been performed in a reaction of 33.4MeV/u ^(17)N on a ^(9)Be target.Energy spectra of n and nitrogen fragments were obtained at different angles.Based on the nuclear diffraction dissociation model,the measured energy spectra and the neutron angular distributions were reproduced quite well assuming that ^(17)N was composed of ^(16)N and n or ^(15)N and 2n interacting with the nonlocal separable potential.The satisfactory agreement between the theoretical calculations and the experimental data shows that the contribution of Coulomb dissociation is negligible in the reaction concerned.展开更多
文摘采用主动式光电倍增管分压电路,通过改变分压电路中电阻和电容的参数值,调节PMT级间电压,以优化输出信号的性能;利用MATLAB编程,控制高频示波器采集信号的形状,对这些数值信号形状数据进行拟合计算,得到信号的平均上升时间,通过不断改变电路元件参数值,对比分析结果,得到分压电路最优的元件工作参数,使PET系统的时间分辨从397 ps上升到359 ps.
基金Supported by the National Natural Science Foundation of China under Grant No 10675149, the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No KJCX3.SYW.N1, and the National Basic Research Programme of China under Grant No 2007CB81500.
文摘Excitation functions have been measured for different projectile-like fragments produced in ^27Al（^19F, x ）y reactions at incident energies from 110. 25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctuations of the excitation functions are observed. The cross-correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle θcm have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion collision of ^27Al（^19F, x）y.
基金Supported by the One Hundred Talents Project and Major Subjects of the Chinese Academy of Sciences under Grant No.KJ95T-03。
文摘Protons are emitted much more affluently in neutron-deficient system ^(40)Ar+^(112)Sn while triton emissions are greater in a neutron-rich system ^(40)Ar+^(124)Sn at incident energy of 30 MeV/u.Similar to neutron,proton emission provied a dominant contribution to neutralize the system N/Z in the decay process of the hot nuclei.The emission of hydrogen isotopes with high energies is much enhanced in the ^(112)Sn system.The original temperature of the hot nuclei in the ^(40)Ar+^(112)Sn reaction is 5.8±0.3 MeV,about 0.7 MeV higher than 5.1±0.3 MeV as in the ^(40)Ar+^(124)Sn reaction.
基金Supported by the National Natural Science Foundation of China for Distinguished Young Scholar under Grand No.19625513National Natural Science Foundation of China under Grant No.19675059+1 种基金Shanghai Science,Technology Development Fund under Grant No.96XD14011Major State Basic Research Development Program(G200077400).
文摘Measurements of the total reaction cross section for^(12-16)C,^(14-17)N and^(16-18)O on carbon target at intermediate energies were performed on RIBLL of HIRFL.A larger enhancement ofσR for^(15)C was observed than that for its neighbors.The analysis of these data indicates possible existence of an anomalous nuclear structure in^(15)C.A new quantity was suggested as the criterion to distinguish anomalous structure nuclei from normal nuclei.
基金Supported by the National Natural Science Foundation of China under Grant No.19575003。
文摘Correlation measurements of neutrons and fragments have been performed in a reaction of 33.4MeV/u ^(17)N on a ^(9)Be target.Energy spectra of n and nitrogen fragments were obtained at different angles.Based on the nuclear diffraction dissociation model,the measured energy spectra and the neutron angular distributions were reproduced quite well assuming that ^(17)N was composed of ^(16)N and n or ^(15)N and 2n interacting with the nonlocal separable potential.The satisfactory agreement between the theoretical calculations and the experimental data shows that the contribution of Coulomb dissociation is negligible in the reaction concerned.
