Correlated fission fragments from the reaction of 25MeV/u ^(40)Ar+^(209)Bi and their further correlation with a par-tides have been studied for peripheral and central collisions simultaneously.The excitation energy at...Correlated fission fragments from the reaction of 25MeV/u ^(40)Ar+^(209)Bi and their further correlation with a par-tides have been studied for peripheral and central collisions simultaneously.The excitation energy at scission deduced from postscission multiplicity is about 1725 MeV.The fission timescale deduced from prescission multiplicity is about 4×10^(21)s.Systematic analysis of the mass and energy distributions of Hssion fragments as a function of the initial temperature of hot fissioning nuclei reveals the existence of different fission behavior of hot nuclei formed in central and peripheral collisions.Experimental data demonstrate the change of Hssion behavior at T~4MeV.展开更多
In order to clarify whether statistical or dynamical treatments for emission of intermediate mass fragments(IMFs)will be needed in the intermediate energy heavy ion collisions,the measured angular and energy distribut...In order to clarify whether statistical or dynamical treatments for emission of intermediate mass fragments(IMFs)will be needed in the intermediate energy heavy ion collisions,the measured angular and energy distributions of IMF(3≤Z≤6)in 25 MeV/n ^(40)Ar+^(nat)Ag were analyzed by means of statistical calculation code GEMINI and quantum molecular dynamics code(QMD).While the angular distribution calculations with GEMINI code are not compatible with the experimental ones,the QMD calculations for inclusive angular distributions and energy spectra of IMF are in good agreement with the measured ones.展开更多
Two-fragment correlation functions have been measured for ^(40)Ar+^(197)Au collisions at E/A=25 MeV.Based on the three-body trajectory calculation,a mean emission time of T~450 fm/c for light fragments was extracted f...Two-fragment correlation functions have been measured for ^(40)Ar+^(197)Au collisions at E/A=25 MeV.Based on the three-body trajectory calculation,a mean emission time of T~450 fm/c for light fragments was extracted from the measured correlation functions.This result suggests that the sequential decay occurs at this energy.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
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
The in-plane and out-of-plane emissions of light charged particles and intermediate mass fragments were measured for ^(40)Ar+^(159)Tb collisions at 30 MeV/nucleon.An in-plane enhancement was observed for mid-rapidity ...The in-plane and out-of-plane emissions of light charged particles and intermediate mass fragments were measured for ^(40)Ar+^(159)Tb collisions at 30 MeV/nucleon.An in-plane enhancement was observed for mid-rapidity light particles and fragments,indicating that a rotational effect exists in this reaction system.This enhancement increased with mass for light particles with Z≤2,but became nearly constant values for fragments with Z≥3.This enhancement was observed to increase strongly with increasing impact parameter.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19235011.
文摘Correlated fission fragments from the reaction of 25MeV/u ^(40)Ar+^(209)Bi and their further correlation with a par-tides have been studied for peripheral and central collisions simultaneously.The excitation energy at scission deduced from postscission multiplicity is about 1725 MeV.The fission timescale deduced from prescission multiplicity is about 4×10^(21)s.Systematic analysis of the mass and energy distributions of Hssion fragments as a function of the initial temperature of hot fissioning nuclei reveals the existence of different fission behavior of hot nuclei formed in central and peripheral collisions.Experimental data demonstrate the change of Hssion behavior at T~4MeV.
基金Supported by the National Natural Science Foundation of China under Grant No.19235011。
文摘In order to clarify whether statistical or dynamical treatments for emission of intermediate mass fragments(IMFs)will be needed in the intermediate energy heavy ion collisions,the measured angular and energy distributions of IMF(3≤Z≤6)in 25 MeV/n ^(40)Ar+^(nat)Ag were analyzed by means of statistical calculation code GEMINI and quantum molecular dynamics code(QMD).While the angular distribution calculations with GEMINI code are not compatible with the experimental ones,the QMD calculations for inclusive angular distributions and energy spectra of IMF are in good agreement with the measured ones.
基金Supported by the National Natural Science Foundation of Chinathe Foundation of the Chinese Academy of Sciences.
文摘Two-fragment correlation functions have been measured for ^(40)Ar+^(197)Au collisions at E/A=25 MeV.Based on the three-body trajectory calculation,a mean emission time of T~450 fm/c for light fragments was extracted from the measured correlation functions.This result suggests that the sequential decay occurs at this energy.
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 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.
基金Supported by the Science Foundation of the Chinese Academy of Sciences。
文摘The in-plane and out-of-plane emissions of light charged particles and intermediate mass fragments were measured for ^(40)Ar+^(159)Tb collisions at 30 MeV/nucleon.An in-plane enhancement was observed for mid-rapidity light particles and fragments,indicating that a rotational effect exists in this reaction system.This enhancement increased with mass for light particles with Z≤2,but became nearly constant values for fragments with Z≥3.This enhancement was observed to increase strongly with increasing impact parameter.
