共查询到20条相似文献,搜索用时 265 毫秒
1.
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
2.
Linear Momentum Transfer in the Reactions Induced by 50MeV/A12C Bombarding 209Bi and 197Au 下载免费PDF全文
JIANG Dong-Xing YE Yan-Lin LIU Hong-Tao LU Xi-Ting HUANG Xiao-Lin XIAO Bin ZHAN Wen-Long ZHU Yong-Tai GUO Zhong-Yan FENG En-Pu XI Hong-Fei LIU Guan-Hua ZHOU Jian-Qun YIN Shu-Zhi ZHU Xiang WANG Bing FENG Jun 《中国物理C(英文版)》1992,16(6):556-562
The Distributions of the linear momentum transfer (LMT) in the reactions induced by 50MeV/u 12C with 209Bi and 197Au were measured using fission fragment angular correlation technique.The most probable value of the linear momentum transfer per projectile,pmp is dependent on the target.173MeV/c and 184MeV/c for 209Bi and 197Au were obtained.In these distributions,there exists a small hump around 0.3 of LMT,which can probably be attributed to the alpha cluster transfer. 相似文献
3.
The behaviour of prompt γ-ray emission in the cold fission of 252Cf was investigated experimentally using a four-parameter correlation technique. A twin gridded ionization chamber was employed to detect the fission signals and to determine the fragment emission angles, and a φ10cm×10cm NaI(T1) detector was used to record the γ-ray energies. The result shows that the angular distribution coefficient of γ-rays emitted in cold fission is twice as large as that in the normal fission.The fact that in the cold fission the number of γ-rays emitted from the light fragments is approximately three times as large as that from the heavy ones can not be explained satisfactorily so far. 相似文献
4.
Liu Zuhua Xu Jincheng Zhang Huanqiao Qian Xing Qiao Yu Lin Chengjian Xu Kan 《中国物理C(英文版)》1994,18(6):489-495
We have succeeded in isolating the complete arising from complete fusion-fission in terms of the fragment folding angle technique,and measured complete fusion-fission cross sections and fragment angular distributions for the 16O+232Th system in the center-of-mass energies between 72.61 and 80.11 MeV.The observed fission excitation function is in quite good agreement with the expectation of the coupled-channels theory.However,the measured fragment angular distributions are more anisotropic than the predictions of both the saddle-point transition-state model and scission model. 相似文献
5.
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
6.
LI Er-Tao LI Zhi-Hong LI Yun-Ju YAN Sheng-Quan BAI Xi-Xiang GUOBing SU Jun WANG You-Bao WANG Bao-Xiang LIAN Gang ZENGSheng FANG Xiao ZHAO Wei-Juan LIU Wei-Ping 《中国物理快报》2009,26(7)
Angular distribution of the 12C(6He,7Li)11B transfer reaction is measured with a secondary 6He beam of 36.4MeV for the first time. The experimental angular distribution is well reproduced by the distorted-wave Born approximation (DWBA) calculation. The success of the present experiment shows that it is feasible to measure one-nucleon transfer reaction on a light nucleus target with the secondary beam facility of the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), Beijing. 相似文献
7.
THE MEASUREMENT OF COMPLETE FUSION CROSS-SECTIONS FOR THE REACTIONS 12C+27Al, 12C+209Bi AND 14N+Pb 下载免费PDF全文
Mica track detectors were used for the measurement of evaporation residues and fission fragments of compound nuclei formed in 12C+27Al, 12C+209Bi and 14N+Pb reactions. The complete fusion cross-sections and excitation functions were then obtained. By using the sharp cut-off model approximation, the values of the critical angular momenta were extracted from the complete fusion cross-sections. The results obtained were compared with the calculations based on current theories for critical angular momentum; they were found to agree within experimental uncertainties. 相似文献
8.
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
9.
RADIOCHEMICAL INVESTIGATION OF MASS DISTRIBUTIONS IN 12C-INDUCED FISSION OF 209Bi AND 238U 下载免费PDF全文
The yields of 15 and 17 fission, products have been obtained by radiochemical determinations in 12C-induced fission of 209Bi and 238U respectively. From these data, the mass distributions of fission fragments are calculated based on three different hypotheses for the charge distribution. The results seem to indicate that the hypothesis of equal charge displacement gives the best fit to the Gaussian distribution for the masses of the fission fragments. By comparison with the mass distributions for 209Bi (12C, f), 238U(12C, f) and 197Au(12C, f) in our early measurement, we find that for fission parameter Z2/A>37, the width of the mass distributions increases with Z2/A rapidly. 相似文献
10.
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
11.
Liu Guoxing Cheng Keliang Yu Xian Zheng Jiwen Jin Weiyang Sun Tongyu Wu Dingqing Zhao Lili Zhang Xiang Yin Xinmin Qin Zhi 《中国物理C(英文版)》1995,19(4):305-309
The angular distributions of the fragments in the range of 4π solid angle for the 600 MeV 40Ar+197Au reaction have been measured using the beam-off γ-ray spectroscopy technique. The features of the fragment angular distributions and the reaction mechanisms of the production of fragments have been discussed. 相似文献
12.
The prompt fission neutron spectra for the neutron-induced fission of 235U at En < 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and constant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well. For the n(thermal)+235U reaction, the average nuclear temperature of the fission fragment, and the probability distribution of the nuclear temperature, are discussed and compared with the Los Alamos model. The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data. 相似文献
13.
LI WEN-XIN SUN TONG-YU SUN XIU-BUA ZHANG TIAN-MEI ZHENG MAN-JIAO DONG TIAN-RONG FU MING 《中国物理C(英文版)》1982,6(3):365-372
Independent yields of 82Br, 96Nb, 112Ag, 130I,132I, 134I, 134mCs, 135mCs, 136Cs and upper limitof independent yield for 140La in the fission of 232Th induced by neutrons of 14 MeVwere determined with nuclear chemistry techniques. The correlation of the fractionalindependent yields in the high yield mass chains with a Gaussian curve of charge dis-tribution has been investigated using various mass formulae and charge distributionhypotheses. The results indicate that the hrpothesis of minimum potential energy witha shell-effected mass equation gives the best fit to the data. The width parameter Cof the charge distribution is found to be 0.80. The large deviations of 32Br and 112Ag from the Gaussian curve seem to show that the low yield in very asymmetric fissioncan be attributed to a narrower width of charge distribution, whereas the high yield insymmetric fission may correlate with a wider width. The trends have been explainedqualitatively in terms of a liquid drop model. There is no evidence for 40-proton subshell effect on the fission yield. 相似文献
14.
Elastic scattering angular distributions of the 14^N+16^O system and the angular distributions of transfer reaction 16^O(14^N,13^C)17^F at ELab=76.2 MeV and 57 MeV have been measured and calculated by means of the exact finiterange distorted-wave Born approximation with the PTOLEMY code. The optical potential parameters for the weakly bound nuclear system 17^F+13^C have been deduced and applied to analyse the elastic scattering angular distributions of the similar systems 17^F+12^C and 17^F+14^N which are taken from literature. The result shows that the transfer reaction with stable projectile and target combination can be used as an alternative method to extract the optical potential parameters for the weakly bound nuclear system. 相似文献
15.
He Zhiyong Li Zuyu Duan Limin Zhang Baoguo Dai Guangxi Jin Genming Fu Yanbiao Wang Hongwei 《中国物理C(英文版)》1998,22(1):13-19
Light charged particles and complex fragments have been measured at forward angles in coincidence with two fission fragments for 40Ar+159Tb reaction at 25MeV/u. These three-body coincident events were sorted as a function of the impact parameter using linear momentum transfer and total transverse momenta methods. Equilibrium statistical emissions of complex fragments from quasi-target residues accompanied by non-equilibrium mid-rapidity components were found to dominate in central collisions, while projectile fragmentations were found to dominate in peripheral collision. Three components of complex-fragments from quasi-target, quasi-projectile and mid-rapidity soures were found in mid-central collision. 相似文献
16.
A SEMI-CLASSICAL ANALYSIS ON THE REACTION 12C+209Bi AT BOMBARDING ENERGIES SLIGHTLY ABOVE THE COULOMB BARRIER 下载免费PDF全文
For reactions induced by light heavy ion such as 12C, at bombarding energy slightly above the coulomb barrier, using semi-classical theory, neglecting macroscopic frictional force, the reaction mechnisms are sorted by the orbital angular momentum of the entrance channel from the classical deflection functions fitting elastic scattering. Moreover, inserting a transfer probability factor representing the Q-Window effect into the semi-classical angular distribution formula of Kalinkin and Grabowski, we obtain a formula for the differential cross-section per unit energy interval. The calculated results, including the elastic scattering angular distributions, energy spectrum and angular distributions of emitted α-particles in quasi-elastic process, complete fusion cross-section, fusion-fission cross-sections and the exitation functions of evaporated neutron, agree with the experimental data on the reaction 12C+209Bi reported by our Institute. 相似文献
17.
WANG DA-YAN LI ZU-YU YUAN SHUANG-GUI GUO ZHONG-YAN JIN GEN-MING XU GUO-JUN YUE HAI-KUI WANG XI-MING CHEN JU-SHENG ZENG WEN-BING XIE HONG-MEI QIAN ZHENG-GUANG ZHANG LI DAI GUANG-XI 《中国物理C(英文版)》1982,6(5):609-615
In this paper, we present energy spectra and angular distributions for the α-par-ticles emitted in the reaction of 12C+197Au at 64 and 67 MeV and for α, Be and B emittedin the reaction at 71.5 MeV. The most-probable energles of the variousproducts emittedin this reaction decrease.with decreasing incident energy. The angular distributions peak near grazing angle.The peak position of the angular distributions shift from--80°to--120°while the projec-tile energy decreases from 71.5 MeV to 64 MeV. These all show the features of the transferreaction. The 6Li product also has been measured and the 8Be particle emitted from thisreaction was detected at 90°to the beam direction using α-α coincident technique at 71.5MeV. The coross section of the 3Be is only few percent at the same angle. 相似文献
18.
DAI Guang-Xi JIN Gen-Ming YUAN Shuang-Gui GUO Zhong-Yan ZENG Wen-Bing CHEN Ju-Sheng LI Zu-Yu WANG Da-Yan XU Guo-Jun 《中国物理C(英文版)》1983,7(1):86-94
The energy spectra and angular distributions of α-particle emitted from 12C-induced reactions with 159Tb, Ag and 89Y targets have been measured. Meanwhile the emitted deutron's angular distributions with 159Tb and 89Y targets and proton's with 89Y target have been also obtained.
The α-energy spectra associated with mentioned reactions have bell-like shape with probable energy near coulomb barrier. However, the main characteristic of the α-angular distribution for 159Tb and Ag targets is peaked at or near the grazing angles. For the case of 89Y target, α-differential cross-sections monotonically decrease with angles beyond 40º. The angular distributions of potons and deutrons nearly decrease exponentially.
The measured α-angular distributions could be divided into two components, one coming from α-evaporation is isotropic, another is anisotropic. The anisotropic component may be explained incomplete-fusion process in which the cross-section can be reproduced by a "Sum-Rule Model" due to J.Wliczynski.
In order to explain the anisotropic component of emitted α-particle, we propose in complete fusion model with a strong-damped sticking rotation, in which the rotation angles and interaction time of the composite system are also estimated. 相似文献
The α-energy spectra associated with mentioned reactions have bell-like shape with probable energy near coulomb barrier. However, the main characteristic of the α-angular distribution for 159Tb and Ag targets is peaked at or near the grazing angles. For the case of 89Y target, α-differential cross-sections monotonically decrease with angles beyond 40º. The angular distributions of potons and deutrons nearly decrease exponentially.
The measured α-angular distributions could be divided into two components, one coming from α-evaporation is isotropic, another is anisotropic. The anisotropic component may be explained incomplete-fusion process in which the cross-section can be reproduced by a "Sum-Rule Model" due to J.Wliczynski.
In order to explain the anisotropic component of emitted α-particle, we propose in complete fusion model with a strong-damped sticking rotation, in which the rotation angles and interaction time of the composite system are also estimated. 相似文献
19.
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
20.
The ^8Li(p, d)^7 Li reaction plays an important role in the inhomogeneous Big Bang nucleosynthesis and in the seed-nuclide production phase for the r-process. For the first time, its angular distribution at backward angles was measured in inverse kinematics at Ec.m.=4.0 MeV by using an ^8Li secondary beam. The result of measurement includes the contributions of ^8Li(p, d0)^7Li and ^8Li(p, d1)^7Li^*. The ^8Li(p, d0)^7Li component is estimated to be 40%-58% in the mixture angular distribution by analysing the measured result. 相似文献