共查询到20条相似文献,搜索用时 11 毫秒
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Nevinitsa V. A. Boyarinov V. F. Fomichenko P. A. Zimin A. A. Glushkov A. E. Moroz N. P. Volkov Yu. N. Kruglikov A. E. 《Physics of Atomic Nuclei》2021,84(8):1397-1404
Physics of Atomic Nuclei - Computational modeling of experiments on measurement of axial distributions of fission reaction rates in configurations of the ASTRA critical facility simulating a HTGR... 相似文献
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From the comparison of terrestrial atmospheric Xe with the primordial Xe (solar, AVCC), a strange component with a fine structure at 132Xe and 131Xe have been found. It was shown that the isotopic composition of this component can be explained neither by mass fractionation of primordial Xe, nor by an admixture of fission products of known nuclei. An analogous Xe was extracted at a low temperature from substances of the natural nuclear reactor, fine-grain samples from Colorado type deposits, ordinary pitchblendes and samples from the epicenter of a A-bomb explosion. It was proved that the strange Xe is a result of different migration rates of β-radioactive Xe precursors which are fission fragments. It is quite possible that the strange component of atmospheric Xe originated as a result of global neutron-induced fission processes during early stages of geological history of the Earth. 相似文献
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M. Maier C. Boudreau F. Buchinger J.A. Clark J.E. Crawford J. Dilling H. Fukutani S. Gulick J.K.P. Lee R.B. Moore G. Savard J. Schwartz K.S. Sharma 《Hyperfine Interactions》2001,132(1-4):517-521
An ion catcher as presented in this contribution is able to create cooled and very clean singly-charged ion pulses out of
a ‘hot’ beam within a very short period of time. Precision measurements on shortlived radioactive nuclides become possible.
This contribution describes experiments with a 252Cf fission source at the ‘gas-cooler’ at ATLAS (Argonne Tandem Linac Accelerating System) at the Argonne National Laboratories
(ANL), Argonne, USA[1]. The system consists of a gas-cell to stop and thermalize the ions, two extraction radio frequency
quadrupole structures (RFQ) to separate the ions from the buffer gas and a buncher RFQ to cool and accumulate the ions. The
system and its performance is investigated with two independent measurements. The transported activity was measured to determine
the efficiency of the system and time of flight measurements (TOF) were performed to determine the transported masses with
respect to the transported activity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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研究了15 MeV/u 197Au+197Au 体系三裂变反应过程中体系的集体运动动能、核-核相互作用势、集体运动总动能以及核子激发能的演化过程,并讨论了该反应过程的能量耗散问题。通过与两裂变时体系总动能εtot 和Θc.m.:关联图作对比,初步得出三裂变反应体系的第一次裂变是极端深度非弹性散射过程;进一步分析了三裂变与两裂变反应体系总动能与碰撞参数的关系,发现小碰撞参数下两裂变比三裂变反应耗散的能量多大约150 MeV,大碰撞参数下三裂变比两裂变反应多消耗300 MeV。We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary ssions of 197Au +197Au system at 15 Mev/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary ssions, we preliminarily concluded that the rst ssion of ternary ssion was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary ssion with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions. 相似文献
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Fission Fragment Angular Correlation in the Reaction Induced by 84.0MeV 16O Bombarded 238U 下载免费PDF全文
QIAN Xing ZHANG Huan-Qiao LIU Zu-Hua XU Jin-Cheng CHEN Shao-Lin XU Kan LU Li-Xin 《中国物理C(英文版)》1993,17(2):173-178
Fission fragment angular distribution and angular correlation in the reaction induced by 84.0MeV 16O bombarded 238U have been measured by using two position-sensitive PPAC with large area.Transfer fission has been removed from total fission using fission fragment angular correlation technique.The contribution to the total fission cross section arising from transfer is about 10%.The anisotropy of fission fragment for transfer-fission is rather small,thus the removal of the transfer fission has little effect on the total fragment angular distribution.Indeed the anisotropy becomes larger by about 5% and anomalously anisotropies still persist. 相似文献
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The dynamical calculation of quasi-fission reaction induced by 10.6MeV/u 84Kr on 27Al is performed using one-body dissipation model.The calculation suggests a fission time larger than 200×10-22 sec.It is found that the threshold for emergence of quasi-fission in the reactoin system is 8MeV/u. 相似文献
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25MeV/u 40)Ar+209Bi裂变反应研究 总被引:1,自引:0,他引:1
实验对25MeV/u 40Ar+209Bi体系的裂变反应,利用线性动量转移的分窗选择不同的激发能,研究裂变动能分布和质量分布与热核初始激发能的关系.实验证实激发能小于380MeV时裂变总动能分布与低激发能复合核相似.激发能大于380MeV时,最可几动能呈现出随激发增加而增加,并出现高能非对称性,而且质量分布宽度随激发能增加而迅速增大. 相似文献
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质子交换膜燃料电池阴极电化学反应对其性能有至关重要的影响。论文基于二电子反应机理,模拟了质子交换膜燃料电池阴极氧和质子电化学反应路径,分析了电化学反应过程中各个步骤能量变化规律和氢氧键形成机制。研究发现,氧分子还原过程中,4个质子逐个接近氧分子,形成氢氧键,最终生成2个水分子;第一个质子采用和氧分子氢氧键102°夹角的方向接近其中一个氧原子,形成第一个氢氧键;当第二个质子和另一个氧原子构成氢氧键时,需要很大的活化能,这是氧还原反应的控制步骤,生成中间产物过氧化氢。研究结果为理解质子交换膜燃料电池电化学反应原理,推动质子交换膜燃料电池的应用具有重要意义。 相似文献
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Measurements of Reaction Cross Section for F Isotopes and Possible Proton Skin Structure for 17F 下载免费PDF全文
ZHANG Hu-Yong SHEN Wen-Qing MA Yu-Gang CAI Xiang-Zhou FANG De-Qing ZHONG Chen YU Li-Ping ZHAN Wen-Long GUO Zhong-Yan XIAO Guo-Qing WANG Jian-Song WANG Jin-Chuan 《中国物理C(英文版)》2002,26(1):35-39
The reaction cross sections σ R of F isotopes on carbon target were measured at intermediate energies via the transmission method. It was found that the reaction cross section of 17F has a little enhancement compared with that of its neighbor isotopes. The difference factor d has been deduced from the measured σ R by using the BUU model and Glauber model. It is enhanced also for 17F compared with its neighbor isotopes. From the above analysis, a possible proton skin structure is suggested for 17F. 相似文献
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The neutron emission is studied following the formation of muonic atoms of 232Th and 239Pu. Energy and time distributions are measured. Various processes which contribute to the measured spectra are considered. A collective resonance model of the muon capture is used to calculate the nuclear excitation function. The probability of the radiationless nuclear excitations and the influence of the presence of the bound atomic muon on the fission barrier are discussed. The existing data for the , are analysed. As a result of the analysis the rates of the prompt and delayed fission events (due to the radiationless mu-atomic transitions and the nuclear muon capture, respectively) are deduced from the experimental data to be 0.006/muon and 0.045/muon for 232Th and 0.10/muon and 0.49/muon for 239Pu, respectively. The increase of the fission barrier for muonic atoms is confirmed. The experimental neutron rates can be consistently explained only if it is assumed that in both nucleides the Kα radiationless transitions do not induce fission. The increase of the fission barrier for 239Pu is hence deduced to be not less than 1.2 MeV. The fate of the atomic muon after the nuclear fission is briefly discussed. Its influence on the interpretation of the present results is found to be small. 相似文献
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本文对含有Botryococcus Braunii UTEX 572的微生物碳捕获电池阴极室内的光合有效辐射(Photosyntheticallyactive radiation,PAR)分布建立数学模型。采用离散坐标法(Discrete Ordinate Method,DOM)求解一维稳态辐射传递方程(Radiative transfer equation.RTE),使用SMARTS(the Simple Model for Atmospheric Transmission of Sunshine)模式对边界条件进行计算。在所建模型基础上,对400~800 nm波长范围的阴极室内PAR分布情况进行计算,并结合Botry-ococcusBraunii UTEX 572的生长动力学对CO2的局部吸收速率进行研究。同时对不同散射处理方法,气泡含量以及藻类浓度对CO2捕获速率的影响进行对比,为改善光在微生物碳捕获燃料电池阴极室的分布和阴极室优化设计提供依据。 相似文献
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Donev Aleksandar Rockwell Jeff ben-Avraham Daniel 《Journal of statistical physics》1999,95(1-2):97-112
Journal of Statistical Physics - We study diffusion-limited coalescence, A+A?A, in one dimension, in the presence of a diffusing trap. The system may be regarded as a generalization of von... 相似文献
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采用广义微扰理论和离散纵标输运计算方法,推导了中心反应率比值对重要核反应参数的灵敏度的计算公式。以一维快基准装置Jezebel-Pu239为例,计算了其中心反应率比值对关键核数据的灵敏度,并结合多群协方差数据,分析了其中心反应率比值计算中由于核数据的不确定度所引入的不确定度及其来源。根据计算结果以及评价数据的协方差信息,建议对Pu-239的非弹截面数据进行更精细的评价,以期降低反应率比的模拟计算不确定度。On the base of the generalized perturbation theory and SN method, the theoretical model for calculating the sensitivity and uncertainty of reaction rates ratio (RRR) versus nuclear data is developed. Taking Jezebel-Pu239 critical benchmarking facility as an example, the sensitivity of F49/F25 ratio versus important nuclear data is calculated, as well as the uncertainty arising from the nuclear data. Basing on the sensitivity and uncertainty analysis as well as the covariance information of input evaluated data, refined evaluation of the inelastic data of Pu-239 is considered as a feasible measure to reduce the uncertainty of reaction rates ratios. 相似文献
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The nuclear potential-energy surface has been calculated on the basis of the modified-oscillator model with the inclusion of the degrees of freedom of axial asymmetry. For the heavier actinides the inner barrier is found to be reduced by up to one MeV. This is in agreement with the results obtained by Pashkevich. For superheavy elements a similar reduction is obtained. 相似文献
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Cross Section Measurements of Neutron-Rich Hg Isotopes in Reaction of 28MeV/u 18O with Thick Natural Lead Target 下载免费PDF全文
By using 28MeV/u 18O beam,an on-line melting lead target equipment and 4π-ΔEβ-γcoincident technique,the relative cross section ratios and absolute cross sections of neutron-rich nuclides 205—208Hg have been measured. The production cross section of 209Hg is extrapolated.The cross section of 207Hg produced by-2p +1n from target decreases suddenly,which may be explained by change of reaction Q value. 相似文献