共查询到19条相似文献,搜索用时 281 毫秒
1.
在Smoluchowski方程的框架内,研究了同位旋对轻裂变同量异位素源110Tc,110Pd,110In和同位素源110,117,124In裂变前粒子发射的影响.计算结果表明:断前粒子发射对裂变源的同位旋有很强的依赖性,随着同位旋的增加,中子发射增强,而轻带电粒子则减弱;对一个高同位旋的系统,质子和α粒子不适合作为提取核耗散强度的实验观测量;核耗散强度的大小不改变同位旋对粒子发射的影响规律 相似文献
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对一个同量异位素链202Fr,202Po,202Tl和一个同位素链189,202,212Po,用裂变扩散模型考察了角动量对裂变前粒子发射同位旋效应的影响.发现断前粒子发射的同位旋效应敏感地依赖于系统的自旋.高的角动量不但弱化了同位旋对粒子蒸发的影响,而且也降低了核耗散对粒子发射的影响.因此,为了更准确地用粒子多重性来提取核耗散系数,选择一个低自旋的复合系统是重要的 相似文献
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用改进了的动力学与统计相结合的模型, 研究了曲率能及压缩能对\,4\,个缺中子裂变系统: 188Pt, 200Pb, 213Fr和224Th的断前中子发射的影响. 计算结果显示用改进模型得到的断前中子多重性相比原来模型的低估要更靠近实验数据. 对于目前工作考虑压缩能的原因进行了讨论. 相似文献
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研究了形变效应对10.6MeV/u 84Kr+27Al反应中断前粒子发射的影响.发现通过测量的裂变前粒子多重性提取的裂变延迟时间将因此从20×10-21s减少到5×10-21s,表明增强的断前粒子发射有一部分来自形变效应的贡献. 相似文献
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偶偶Cd同位素核的形变HF态及负宇称带研究 总被引:1,自引:0,他引:1
将具有正宇称的轨道空间扩大到包含具有负宇称的1h11/2轨道,采用修正的表面δ相互作用(MSDI),对104Cd,106Cd,108Cd,110Cd,112Cd,114Cd和116Cd等7个偶偶核作了形变HF计算.得到了基态和一些激发态的解.同时,还用近似角动量投影形变Hartree-Fock(PDHF)方法对108Cd和110Cd进行了能谱计算,得到其正、负宇称带的解,计算结果与实验谱基本一致. 相似文献
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在统计模型的框架内研究了In核在三维空间的转动自由度对10.6和8.5MeV/u 84Kr+27Al碰撞裂变前粒子发射的影响.发现对后一个轰击能,断前粒子发射不敏感于转动自由度;对前一个能量,转动自由度的引入使提取的裂变延迟时间从20×10-21s减少到7.5×10-21s,表明了它对裂变前粒子蒸发的影响,计算结果也表明仅有转动自由度并不能完全解释In核的断前粒子增强发射现象.发现了转动自由度在粒子发射中所起的作用对系统的激发能有一定的依赖关系. 相似文献
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将单粒子薛定谔液体理论应用于轴对称形变核的集体运动.也给出了一个相反的例子,即在各向异性谐振子势中处于稳定形变的任意数目的独立核子.而且,通过填充与主量子数nx,ny和nz的可能值相应的单粒子态来构成s-d壳偶偶核:20Ne,24Mg,28Si,32S和36Ar的基态,并计算了作为谐振子参数hωx,hωy和hωz的函数的这些核的推转模型、刚体模型和稳态模型转动惯量.这些谐振子参数用与质量数A、中子数N、质子数Z和形变参数β有关的非形变参数hω00来描述.这些核的推转模型转动惯量的理论计算结果与实验数据符合甚好.而且,所考虑的轴对称形变核可能是扁椭球形的,也可能不是扁椭球形的,其中24Mg是惟一高度形变的.20Ne和24Mg这两个核的刚体模型和稳态模型转动惯量也与实验数据符合甚好. 相似文献
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Isospin effects on particle emission of fissioning isobaric sources
202Fr, 202Po, 202Tl and isotopic sources
189,202,212Po, and its dependence on the excitation energy are studied via Smoluchowski equations. It is shown that with increasing the
isospin of fissioning systems, charged-particle emission is not
sensitive to the strength of nuclear dissipation. In addition, we
have found that increasing the excitation energy not only
increases the influence of nuclear dissipation on particle
emission but also greatly enhances the sensitivity of the emission
of pre-scission neutrons or charged particles to the isospin of
the system. Therefore, in order to extract dissipation strength
more accurately by taking light particle multiplicities it is
important to choose both a highly excited compound nucleus and a
proper kind of particles for systems with different isospins. 相似文献
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用扩散模型研究了壳对幻数附近的核,即204Pb,208Pb,212Pb和128Sn,132Sn,136Sn,在裂变过程中蒸发轻粒子多重性的影响.发现壳能够影响粒子发射的同位旋依赖性,并且该影响的大小与复合系统的自旋和激发能有关.计算表明角动量在壳影响同位旋相关的粒子发射中起到了显著的作用,而高激发能弱化了壳的影响. 相似文献
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利用兰州4π带电粒子探测器阵列测量带电粒子多重性,研究了55MeV/u 40Ar+58,64Ni核反应中He和中等质量碎片的产额与反应系统同位旋的关系,以及这种同位旋效应与反应系统的碰撞参数(即碰撞的激烈程度)、系统的激发能的变化关系,对两个反应系统,观察到带电粒子多重性中He的比分随带电粒子多重性的增加而增大,带电粒子多重性中IMF的比分随带电粒子多重性的增加而先增大,后减小的规律.两个反应系统虽然具有相同的核电荷数,但轻粒子He和中等质量碎片在多重性中的比分有明显的同位旋相关性。 相似文献
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WU Feng YE Wei CHEN Na 《理论物理通讯》2007,48(4):710-712
Using a Langevin equation coupled with a statistical model, we calculate pre-scission giant dipole resonance (GDR) γ-ray multiplicity of nuclei 194 pb, 200Pb, 206Pb, and 200 Os. It is demonstrated that with increasing the isospin asymmetry of these fissioning nuclei the sensitivity of the emitted γ multiplicity to the nuclear viscosity coefficient is decreased significantly. For 200Os nuc/eus, this γ-ray emission is no longer sensitive to the magnitude of the viscosity coefficient. In addition, the effect of the isospin asymmetry on the γ rays as a probe of nuclear dissipation is reduced with increasing angular momentum. These results suggest that to obtain a more accurate information of the viscosity coemfficient by the measurement of pre-scission GDR γ-ray multiplicity it is better to choose those compound systems with small isospin asymmetry and low spin. 相似文献
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The 140~MeV/u ^40,48Ca+^9Be and ^58,64Ni+^9Be
reactions are simulated by the statistical abrasion ablation model,
and the simulation results are compared to the National
Superconducting Cyclotron Laboratory (NSCL) experimental data. By
comparing the fragment isotopic distributions of ^40,48Ca and
^58,64Ni, we study the isospin effect in the projectile
fragmentation induced by the neutron-rich nuclei at intermediate
energy experimentally and theoretically. It is found that the
isospin effect in projectile fragmentation decreases and even
disappears as the violence of the collision increases. 相似文献
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Isospin Effect on Relative State Population Temperature in the Reactions 40Ar+ 112,124Sn at 30MeV/u
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HU Rong-Jiang WU He-Yu ZHU Yong-Tai JIN Gen-Ming DUAN Li-Min XIAO Zhi-Gang WANG Hong-Wei LI Zu-Yu WANG Su-Fang ZHANG Bao-Guo WEI Zhi-Yong LU Zhao-Hui ZHU Hai-Dong FENG Zhao-Qing YUAN Xiao-Hua 《中国物理C(英文版)》2004,28(2):152-157
An array of 13 detector telescopes has been used for detecting small-angle particle-particle correlations in the reactions 40Ar+112,124Sn at 30MeV/u. The α-α correlation functions were extracted from two-particle coincident events. A three-body trajectory code MENEKA was used to calculate the background correlation function. The detection efficiency was calculated by using the Monte-Carlo method. After subtracting the background correlation and making the detection efficiency correction, the temperatures of 4.18±0.25 0.21 MeV and 4.10±0.22 0.20MeV are obtained from relative populations of 8Be states for the reaction systems with different isospin,40Ar+112Sn and 40Ar+124Sn, respectively. From the relationship between the state population temperature and outgoing particle energies, it is found that the emission temperature decreases with increase of the particle energies for both studied reaction systems. For the neutron deficient system 40Ar+112Sn the emission temperature is 5.13±0.30 0.26MeV for the lower emitting particle energies and 3.87±0.37 0.29MeV for the higher emitting particle energies. And for the neutron rich system 40Ar+124Sn the emission temperature is 5.39±0.30 0.26MeV for the lower emitting particle energies and 3.32± 0.28 0.23MeV for the higher emitting particle energies. This kind of isospin dependence is discussed. 相似文献