We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-...We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-area parallel-plate avalanche counters, which can deliver the position and arrival timing information of the fragments. The start timing information is provided by the radio frequency of the cyclotron. Fission events were reconstructed using the velocities of the two FFs. The broadening of both the velocity distribution and azimuthal difference of the FFs decreases with the folding angle, in accordance with the picture that fast fission occurs. The anisotropic angular distribution of the fission axis also consistently reveals the dynamic features of fission events.展开更多
In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou (HIRFL) was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12...In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou (HIRFL) was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12C and ^18O ions with energies up to 75 MeV/u were obtained using the activation method. The neutron dose equivalent rates of 60 MeV/u ^18O on various thick targets at different angles were measured with a modified A-B remmeter. Our results are compared with those of other reports.展开更多
In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragmen...In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and |β| with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.展开更多
The high spin states of 106pd have been populated through the 100Mo(11B, lp4n)106Pd reaction using a beam energy of 60 MeV provided by the Beijing HI-13 tandem accel- erator at China Institute of Atomic Energy. By a...The high spin states of 106pd have been populated through the 100Mo(11B, lp4n)106Pd reaction using a beam energy of 60 MeV provided by the Beijing HI-13 tandem accel- erator at China Institute of Atomic Energy. By analyzing the V-3' coincidence relation and DCO raios of transitions, 3 rotational bands with 13 new states and 22 new 7 transitions belonging to 106pd were constructed. Bands 2 and 3 with negative parity were supposed to build on the vh1l/297/2 and vh11/2ds/2 configuration, respectively.展开更多
Using the isospin-dependent quantum molecular dynamics model, the entropy of an intermediate-energy heavy ion collision system after the reaction and the number of deuteronlike and protonlike particles produced in the...Using the isospin-dependent quantum molecular dynamics model, the entropy of an intermediate-energy heavy ion collision system after the reaction and the number of deuteronlike and protonlike particles produced in the collision is calculated. In the collision, different parameters are used and the mass number used here is from40 to 93 at incident energy from 150 MeV to 1050 MeV. We build a new model in which the density distribution of the reaction product is used to calculate the size of the entropy. The entropy calculated with this model is in good agreement with experimental values. Our data reveals that with the increase of the neutron-proton ratio and impact parameter, the entropy of the reaction system decreases, and it increases with the increase of system mass and reaction energy.展开更多
Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information abou...Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information about the decaying nuclei.Fragmentation events may result in high yields of boson particles,especially alpha particles,and may carry important information about the nuclear Bose Einstein condensate(BEC).We study‘in medium’fourαcorrelations and link them to the‘fission’of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α.Using novel techniques for the correlation functions,we confirm the resonance of 16O at 15.2 MeV excitation energy,and the possibility of a lower resonance,close to 14.72 MeV.The latter resonance is the result of allαparticles having 92 keV relative kinetic energies.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11875174,11961131010,and 11961141004)the Polish National Science Center(No.2018/30/Q/ST2/00185)。
文摘We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-area parallel-plate avalanche counters, which can deliver the position and arrival timing information of the fragments. The start timing information is provided by the radio frequency of the cyclotron. Fission events were reconstructed using the velocities of the two FFs. The broadening of both the velocity distribution and azimuthal difference of the FFs decreases with the folding angle, in accordance with the picture that fast fission occurs. The anisotropic angular distribution of the fission axis also consistently reveals the dynamic features of fission events.
文摘In this work, the neutron radiation field at Heavy Ion Research Facility in Lanzhou (HIRFL) was investigated. Total neutron yields, spectra and angular distributions in the bombardment of various thick targets by 12C and ^18O ions with energies up to 75 MeV/u were obtained using the activation method. The neutron dose equivalent rates of 60 MeV/u ^18O on various thick targets at different angles were measured with a modified A-B remmeter. Our results are compared with those of other reports.
基金Project supported in part by the Shanghai Development Foundation for Science and Technology of China (Crant Nos 05XD14021 and 03QA14066), the National Natural Science Foundation of China (Grant Nos 10328259, 10135030, 10405032, 10405033 and 10475108), the Major State Basic Research Development Program of China (Contract No G200077404).
文摘In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and |β| with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.
基金supported by the Major State Basic Research Development Program (2007CB815000)by National Natural Science Foundation of China (Nos. 11075214,10927507, 10975191, 10675171, 10105015, 10375092, 10575133, 11175259)
文摘The high spin states of 106pd have been populated through the 100Mo(11B, lp4n)106Pd reaction using a beam energy of 60 MeV provided by the Beijing HI-13 tandem accel- erator at China Institute of Atomic Energy. By analyzing the V-3' coincidence relation and DCO raios of transitions, 3 rotational bands with 13 new states and 22 new 7 transitions belonging to 106pd were constructed. Bands 2 and 3 with negative parity were supposed to build on the vh1l/297/2 and vh11/2ds/2 configuration, respectively.
文摘Using the isospin-dependent quantum molecular dynamics model, the entropy of an intermediate-energy heavy ion collision system after the reaction and the number of deuteronlike and protonlike particles produced in the collision is calculated. In the collision, different parameters are used and the mass number used here is from40 to 93 at incident energy from 150 MeV to 1050 MeV. We build a new model in which the density distribution of the reaction product is used to calculate the size of the entropy. The entropy calculated with this model is in good agreement with experimental values. Our data reveals that with the increase of the neutron-proton ratio and impact parameter, the entropy of the reaction system decreases, and it increases with the increase of system mass and reaction energy.
基金Supported by the National Natural Science Foundation of China(11765014,11865010,11905120,I1605097,U2032146,11421505)the Robert A.Welch Founda-tion(A-1266)+6 种基金the US Department of Energy(DE-FG02-93ER40773)Natural Science Foundation of Inner Mongolia(2018MS01009,20191001)the Chinese Academy of Sciences(CAS)President's International Fellowship Initiative(2015VW A070)the Strategic Priority Research Program of the Chinese Academy of Sci-ences(XDB16,XDPB09)the Program for Young Talents of Science and Technology in Univrities of Inmer Mongolia Autonomous Region(NJYT-18-B21)the Doctoral Seientifie Research Foundation of Inner Mongolia University for Nationalities(BS365.BS400)The Fundamental Research Funds for the Central University(GK201903022)。
文摘Heavy ion collisions near the Fermi energy produce a‘freezout’region where fragments appear and later decay,emitting mainly neutrons,protons,alpha particles,and gamma rays.These decay products carry information about the decaying nuclei.Fragmentation events may result in high yields of boson particles,especially alpha particles,and may carry important information about the nuclear Bose Einstein condensate(BEC).We study‘in medium’fourαcorrelations and link them to the‘fission’of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α.Using novel techniques for the correlation functions,we confirm the resonance of 16O at 15.2 MeV excitation energy,and the possibility of a lower resonance,close to 14.72 MeV.The latter resonance is the result of allαparticles having 92 keV relative kinetic energies.