共查询到20条相似文献,搜索用时 31 毫秒
1.
Isospin Effect on the Emission Mechanism of Hot Nuclei in 35MeV/u 40Ar +112Sn/124Sn Reactions 下载免费PDF全文
Wu Heyu Xiao Zhigang Li Zuyu Wang Hpmgweo Duan Limin Zhang Baoguo Liu Yongying Wang Sufang Jin Genming Xiao Guoqing Guo Zhongyan Zhu Yongtai 《中国物理C(英文版)》1999,23(11):1115-1118
As an extension of radioactive ion beam physics, the research on isospin dependent properties of hot nuclei has increasingly attracted considerable interest. The isospin effect on the decay of hot nuclei in reactions 35MeV/u 40Ar+112Sn/124Sn has been investigared. It is concluded that due to Coulomb repulsion and instability, proton-rich hot nuclei probably emit prides such as a with high energy to increase their neutron-proton ratio. Moreover, the decay chain for those particles is seemingly long and the emission Probability is high. Thus, the conventional observations, for instance, the ‘slope temperature’ extracted from energy spectrum, may very appreciably with the measured particles. 相似文献
2.
Entrance Channel Dependence of the Correlation Function of IMFs in 36Ar+112,124Sn at 35MeV/u 下载免费PDF全文
HU Rong-Jiang XIAO Zhi-Gang WU He-Yu DUAN Li-Min WANG Hong-Wei YUAN Xiao-Hua JIN Gen-Ming ZHU Yong-Tai LI Zu-Yu WANG Su-Fang XU Hu-Shan ZHANG Bao-Guo WEI Zhi-Yong FENG Zhao-Qing FU Fen 《中国物理C(英文版)》2007,31(4):350-356
The reduced velocity correlation functions of the Intermediate Mass Fragments (IMFs) were measured in the reactions of 36Ar+112,124Sn at 35MeV/u. The anti-correlation at small reduced velocities is more pronounced in 36Ar+124Sn system than that in 36Ar+112Sn system. The difference of the correlation functions between the two reactions is mainly contributed by the particle pairs with high momenta. A three-body Coulomb repulsive trajectory code (MENEKA) is employed to calculate the emission time scale of IMFs for the both systems. The time scale is 150fm/c in the 36Ar+112Sn system and 120fm/c in the 36Ar+124Sn system, respectively. A calculation based on an Isospin dependence Quantum Molecular Dynamics code (IQMD) reveals that the emission time spectrum of IMFs is shifted slightly leftwards in 36Ar+124Sn compared with that in the 36Ar+112Sn system, indicating a shorter emission time scale. Correspondingly, the central density of the hot nuclei decreases faster in 36Ar+124Sn than in 36Ar+112Sn. 相似文献
3.
XIAO Zhi-Gang WU He-Yu LI Zu-Yu JIN Gen-Ming WANG Hong-Wei DUAN Li-Min ZHANG Bao-Guo HU Rong-Jiang WEI Zhi-Yong LIU Yong-Ying WANG Su-Fang LU Zhao-Hui ZHU Yong-Tai ZHU Hai-Dong 《中国物理C(英文版)》2001,25(6):494-499
Isotope ratios,defined as the yield ratio of two isotopes with the same charge,were analyzed as a function of kinetic energy of outgoing particles at 20° in the reactions of 40Ar+112,124Sn and 5°in36Ar+112,124Sn at incident energy of 35MeV/u. Isotope ratios between the neutron-deficient isotopes and stable isotope increase with kinetic energy,while those between the neutron rich isotopes and stable isotope decrease. This different behavior was observed similar for both 112Sn and 124Sn targets. The isotope ratios show rather obvious target dependence at 20° and little target dependence at 5°. As the outgoing energy getting down,the N/Z ratio of the fragmentation products at 5° diverts gradually from the N/Z ratio of the projectile to that of the system. These observations indicate that the isospin degree of freedom does not reach complete equilibrium in the peripheral or semi-peripheral collision at this bombarding energy. 相似文献
4.
INFLUENCE OF THE NEUTRON NUMBER OF TARGET NUCLEUS ON CROSS SECTIONS OF PARTICLES EMISSION IN 12C+112,124Sn 下载免费PDF全文
The energy spectra and angular distributions of Li, Be, B particles emitted from the 12C+112Sn and 12C+124Sn reactions at EL=70.0MeV are measured. The angular distributions of the Li, Be, and B particles are found to be peaked around the grazing angle, without any forward peaked component.
The experimental results also showed that the cross section for emission is larger in 12C+112Sn reaction than that in 12C+124Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability. 相似文献
The experimental results also showed that the cross section for emission is larger in 12C+112Sn reaction than that in 12C+124Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability. 相似文献
5.
Temperatures and Excitation Energies of Hot Nuclei in Reactions of 40Ar+natAg,209Bi at MeV/u 下载免费PDF全文
Yin Shuzhi Jin Weiyang Zhang Chun Jin Genming Zheng Jiwen Wu Enjiu Tan Jilian Li Zuyu Wang Sufang Song Mingtao Wu Heyu He Zhiyong Jiang Dongxing Qian Xing 《中国物理C(英文版)》1997,21(8):680-685
Coincidence measurements of fission fragment and light charged particle have been perfotrmed for the reactions of 40Ar+natAg,209Bi at E/A=25MeV using 4 PPAC and 11 sets of ΔE-E telescopes.Angular correlations of fission fragment were ploted as a function of the folding angle between the two detected fission fragments.The linear momentum transfer distributions were derived by measuring angular correlations.The backward spectra of light particles detected in coincidence with fission fragments having different average〈LMT〉are analyzed with Maxwell distribution.After some corrections the initial temperatures of the hot nuclei are determined from the energy spectra.The excitation energies corresponding to the different average〈LMT〉are obtained considering the reaction Q values and pre-equilibrum emission.In the central collision of the 40Ar+natAg,209Bi reactions,excitation energies are measured to be about 4.2MeV/u,2.4MeV/u and temperatures about 6.1MeV,5.5MeV,respecdvely.In semi-central collision,excitaionen energies are measured to be about 3.5MeV/u,1.9MeV/u and temperatures about 5.8MeV,4.8MeV respectively. 相似文献
6.
7.
By means of using an isospin-dependent Boltzmann-Langevin equation which includes isospin-dependent symmetry energy, Coulomb energy, isospin-dependent nucleon-nucleon cross sections, Pauli blocking, and initialization, the radial expansion flow of reaction systems 40Ca+58Ni and 40Ca+58Fe at 53, 100, 150, and 200 MeV/u in the central collisions were studied. It has shown that the more neutron rich system exhibits smaller radial expansion flow. It was found that the neutron rich system had smaller threshold energy which may provide a new method to determine the isospin dependent nuclear equation of state from calculated result and linear fitting result. 相似文献
8.
The Angular Distributions of intermediate Mass Fragments Emittsd in 30 MeV/u 40Ar+58,64Ni and 115In Reactions 下载免费PDF全文
Gou Quanbu Zhu Yongtai Xu Hushan Wei Zhiyong Lu Jun Zhang Yuhu Wang Qi Li Songlin Wu Zhongli 《中国物理C(英文版)》1999,23(4):328-333
The angular distributions of intermediate mass fragments with Z=3-19 emitted in 30 MeV/u 40Ar+58,64Ni and 115In reactions over an angular range of 5°—140°have been measured.Exponential distribution function: dσ/dΩ=N·exp(-θ/a) was used tO fit the measured angular distributions.We have extracted the decay factor a that can be connected with the interaction time τ, and the factor N that is related to the intensity of the emission source.The relationships of a(Z) with Z and N(Z) with Z for different reaction systems and different angular ranges have been discussed. The dependence of angular distributions on isospin and the symmetry of reaction system have also been discussed. 相似文献
9.
Emission Time Measurements of Light Particles from 40Ar+197Au Collisions in Intermediate Energies 下载免费PDF全文
He Zhiyong Duan Limin Li Zuyu Jin Genming Luo Qingzheng Wu Heyu Zhang Baoguo Wen Wanxin Qi Yujin Dang Bingrong Dai Guangxi 《中国物理C(英文版)》1996,20(1):8-12
Particle-particle correlation functions have been measured for 40Ar+197Au collisions at E=25 MeV/u.Emission time of light particles has been extracted from correlation functions using the three-body trajectory model.The average emission time varies with the energy of particles. It decreases from about 300 fm/c for low energy particles to about 100fm/c for energetic particles. 相似文献
10.
In order to treat the waste material of nuclear power and develop new type of clean nuclear power,it is necessary to measure the neutron adta of long half life nuclei existed in the waste material.The prompt spontaneous neutron spectrum is one of the most important unclear data for new type nuclear power facilities as well as for understanding the mechanism of fission neutron emission.The measurements of 248Cm/252Cf spontaneous prompt fission neutron spectrum in the neutron energy range form 200keV to 12MeV wer performed by using TOF method.A micro-ionization chamber aws used as fission fragment detector and stibene crystal as neutron detector.The flying paths of neutrons for the measurements were 30cm,50cm and 100cm respectively.The spontaneous prompt fission neutron spectrum of 248Cm was fitted by the Maxwellian distribution and the temperature was determined as (1.401±0.006)MeV in the corresponding neutron energy range. 相似文献
11.
Measurement of Angular Distributions for Elastic Scattering of 16O+94Zr and 16O+116Sn Reactions 下载免费PDF全文
HU GuiQing ZHAO Kui JIANG Hua GUO JiYu FU ChangBo LU XiuQin LIANG Gang LI ZhiChang LI ShuYuan LIU JianCheng 《中国物理C(英文版)》2000,24(8):725-731
The angular distributions for elatic scattering of the two systems,16O+94Zr at energies 52,57,59,62,72,82 and 92 MeV and 16O+116Sn at energies 57,59,62,67,72,82 and 92 MeV have been measured.The scattered ions were datected by the Beijing Q3D magnetic spectrometer and its heavy ion focal plane detector.The optical model analysis of the data was made with the Coupled Channels code ECIS, and the optical potential parameters have been obtained by fitting the data.Within the limited data,the phenomenon of the ‘threshold anomaly’is observed. 相似文献
12.
Space-Time Evolution of Projectile-Like Fragment Emission for 40Ar +natAg Reaction at 30MeV/u 下载免费PDF全文
WANG HongWei LI ZuYu HE ZhiYong DUAN LiMin ZHANG BaoGuo FU YanBiao JIN GenMing WU HeYu DAI GuangXi 《中国物理C(英文版)》2000,24(1):35-40
The emission time of intermediate mass fragments (IMF) has been studied as a function of spatial evolution of the emission source for 40Ar+natAg reaction at 30MeV/u, and the spatial-time evolution of projectile-like fragments emission has also been discussed. The investigation for spatial-time evolution of the reaction system shows that the emission time of the IMF mainly depends on the correlation functions and the density of nuclear matter, and that it is not sensitive to the mass number of emitting sources. For high-energy fragments, a smaller nuclear density would lead to a smaller assignment for emission time τ; therefor the τ values extracted from the normal nuclear density could be taken as upper limits of real τ values. For the mid-velocity fragments, their emission times do not change with size of the source and these τ values could be taken as the real values directly. 相似文献
13.
Excitation Energy and Temperature of Compound Nuclei in the Reaction of 35MeV/u 40Ar+197Au 下载免费PDF全文
DUAN Li-Min WU He-Yu JIN Gen-Ming WANG Su-Fang LI Zu-Yu WEI Zhi-Yong ZHANG Bao-Guo WANG Hong-Wei XIAO Zhi-Gang LIU Yong-Ying HU Pei-Gang LU Zhao-Hui TIAN Wen-Dong GOU Quan-Bu 《中国物理C(英文版)》2003,27(2):118-123
The fission fragments in the reaction of 40Ar+197Au have been measured coincidently with light charged particles at 35MeV/u by using large area position sensitive detectors and Si-detectors. The velocities of the fissioning compounds are deduced based on the fragments and the excitation energies of the compounds calculated with a hypothesis of massive transfer and taking into account the influence of pre-equilibrium emission of light particles. As the same time,the temperatures of the compounds are extracted by using the energy spectra of the backward light charged particles measured coincidently with fission fragments. The temperature-excitation energy curve does not present the behaviour predicted by the theories. 相似文献
14.
Azimuthal Correlations of Fragments with Light Charged Particles in Reaction of 25MeV/u 40Ar+115In 下载免费PDF全文
WANG Jin-Chuan ZHAN Wen-Long GUO Zhong-Yan XI Hong-Fei ZHOU Jian-Qun ZHAO You-Xiong 《中国物理C(英文版)》2001,25(1):16-22
The large angle correlations for in-plane and out-of-plane have been measured for the pairs of the fragments and light charged particles (LCPs) in the reaction of 25MeV/u 40Ar+115In. The azimuthal correlation functions and the azimuthal asymmetry factors were obtained. The azimuthal correlation functions of all pairs between fragments and a particles are of minimum value in φ=90°plane. It indicates that the LCPs and fragments formed in the reaction exhibit an enhanced emission in the reaction plane due to collective rotation-like effect induced by attractive mean field. The more heavier the masses of the coincident LCPs and fragments are, the more stronger the left-right asymmetries of the coincident particles with respect to the beam direction in the reaction plane are, the more preferential the particle emission to the direction opposite to the coincident reaction products is. Along with the increase of the mass of the coincident LCPs and fragments, the influences of the sequential decay and particle final state interactions on the azimuthal correlation functions of the correlated pairs in the φ=0° plane decrease and vanish at last, the collective rotation-like effect is enhanced, and the azimuthal asymmetries increase. 相似文献
15.
36Ar+112,124Sn反应中小角关联出射的中等质量碎片(IMF)约化速度关联函数. 结果表明36Ar+124Sn反应系统中的约化速度关联函数在小约化速度处的反关联程度比36Ar+112Sn反应系统中的强, 表现出明显的入射道依赖性. 考察出射粒子对的单核子总动量时, 发现这种差异主要来自于高动量粒子对的贡献. 用三体弹道理论模型MENEKA分别计算了两个系统的IMF发射时标, 在36Ar+112Sn反应系统中约为150fm/c, 而在36Ar+124Sn反应系统中, 约为120fm/c. 同位旋相关的量子分子动力学计算表明, 36Ar+124Sn系统中IMF的发射时间谱比36Ar+112Sn系统略有前移, 相应地, 其中心密度从最高点随时间的下降亦比36Ar+112Sn系统略快. 相似文献
16.
WANG Hua-Min WANG Yong-Chang YUAN Jun-Qian WANG Xue-Zhi REN Zhong-Liang 《中国物理C(英文版)》1989,13(4):353-356
The cross section for 107Ag(n,2n)106mAg has been measured by using the activation method relative to the cross section of 27Al(n,α)24Na in the neutron energy range of 13.50—14.73MeV.The values of 469±22,480±22,503±24,538±25,555±25,572±26mb were obtained at the 13.50,13.60,13.90,14.10,14.35,and 14.73MeV neutron energy,respectively.The results are compared with the published data.The neutron energies were determined by activity ratios of Nb and Zr foils. 相似文献
17.
Azimuthal Distribution and Azimuthal Correlation of the Particles in 10.6MeV/u 84Kr+27Al Collision 下载免费PDF全文
The light charged particle emission in coincidence with fragmemts in 10.6MeV/u 84Kr+27Al collision is studied.Emphasis is laid on the characters of two-order anisotropy coefficient of Fourier expansion up to two order from fitting particle azimuthal distribution and particle-particle azimuthal correlation.The derived results prove that particle emission is statistically independent with the same azimuthal distribution in each event.It is found that two-order anisotropic coefficient depends weakly on the fragment mass and increases with increasing emitted particle mass. 相似文献
18.
Using the isospin- and momentum-dependent hadronic transport model IBUU04, we have in-vestigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three isotopic reaction systems 132Sn+124Sn, 124Sn+112Sn and 112Sn+112Sn which are of the same total proton number but different isospin asymmetry. We find that the kinetic-energy distributions of the pre-equilibrium neutron/proton ratio are quite sensitive to the density-dependence of symmetry energy at incident beam energy E/A = 400 MeV,and the sensitivity increases as the isospin asymmetry of the reaction system increases. 相似文献
19.
Space-Time Evolution During Emission of Intermediate Mass Fragmentform 40Ar+159Tb Reaction at 30 MeV/u 下载免费PDF全文
He Zhiyong Li Zuyu Duan Limin Zhang Baoguo Jin Genming Dai guangxi Wang Hongwei Fu Yanbiao 《中国物理C(英文版)》1998,22(8):678-683
The emission time of intermediate mass fragments has been studied as afunction of spatial evolution of the source for 40Ar+159Tb reaction at 30 MeV/u.Reduction of the mass number of source has a very small effect on the extractedemission time. For the high-energy fragments with a short emission time ≤100fm/c,a smaller nuclear density would lead to a smaller assignment for, therefore thevalues extracted in the normal nuclear density could be taken as upper limits of realvalues. For the low-energy fragments, their emission times do not vary with size ofthe source and these values could be taken as real values. 相似文献
20.
LIU Shao-Xiang 《中国物理C(英文版)》1985,9(3):321-326
The angular distribution has been measured for elastic scattering on 40Ar with 11B and for the single proton transfer reaction 40Ar(11B, 10Be)41K at the incident beam energy of 50 MeV. The elastic scattering cross section has been fitted in terms of the optical model. The EFR-DWBA aproach with recoil effect has been used to analyze the differential cross section. The spectroscopic factor was extracted. 相似文献