Y. Alhassid, G. F. Bertsch, P. Fanto, T. Kawano
A recent article (D.A. Brown, et al., Phys. Rev. C98 024616 (2018)) rproposed a modification of the cross section formula used in practical calculations of compound nucleus reactions. We discuss the main concepts and approximations of statistical reaction theory and conclude that the standard practical implementations of the cross section formula remain the preferred choice.
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Model for compound nucleus formation in various heavy-ion systems
本文提出统一统计模型描述轻、重及超重离子系统中复合核形成，揭示形成势垒与准弹性势垒的竞争机制，计算结果与实验数据吻合。
Modelling of compound nucleus formation in fusion of heavy nuclei
提出了一个新的模型，该模型包括单粒子（s.p.）本文提出了一种结合系统宏观演化的运动模型来描述重核聚变中复合核的形成。非绝热性最初使入口系统保持在其接触构型附近，但从非绝热到绝热势能面（PES）的逐渐转变导致聚变或准裂变。CN形成概率的直接测量对于区分当前模型至关重要。
The understanding of the fusion probability is of particular importance to reveal the mechanism of producing superheavy elements. We present a microscopic study of the compound nucleus formation by combining time-dependent density functional theory, coupled-channels approach, and dynamical diffusion models. The fusion probability and compound nucleus formation cross sections for cold-fusion reactions $^{48}$Ca+$^{208}$Pb, $^{50}$Ti+$^{208}$Pb, and $^{54}$Cr+$^{208}$Pb are investigated and it is found that the deduced capture barriers, capture cross sections for these reactions are consistent w…
Entrance-channel Mass-asymmetry Dependence of Compound-nucleus Formation Time in Light Heavy-ion Reactions
在半经典耗散碰撞模型的框架下，研究了轻重离子反应中复合核形成时间与入口道质量不对称性的关系。模型计算成功地应用于$^{38}$复合核的形成，如通过$^{9}$ + $^{29}$，$^{11}$ + $^{27}$，$^{12}$ + $^{26}$和$^{19}$-F + $^{19}$-F进入通道布居。其他几个轻复合系统的形状演变似乎与实验观察到的所谓的“融合抑制因子”一致。正如先前在更大质量的系统中发现的那样，对于聚变-蒸发过程，入口通道的质量不对称自由度似乎决定了不同机制之间的竞争以及所涉及的时间尺度。
The large body of experimental data on the fission fragments anisotropies are analyzed in several heavy-ion induced fission reaction systems. The entrance channel mass asymmetry parameters of these systems put on the both sides of the Businaro-Gallone mass asymmetry parameters. The role of the mass numbers of the projectile and the target in the prediction of a normal or an anomalous behavior in angular anisotropy, as well as the validity of standard saddle-point statistical model are considered. The average contribution of non compound nucleus fission for the systems with an anomalous behavio…
A statistical model description of heavy ion induced fusion-fission reactions is presented where shell effects, collective enhancement of level density, tilting away effect of compound nuclear spin and dissipation are included. It is shown that the inclusion of all these effects provides a consistent picture of fission where fission hindrance is required to explain the experimental values of both pre-scission neutron multiplicities and evaporation residue cross-sections in contrast to some of the earlier works where a fission hindrance is required for pre-scission neutrons but a fission enhanc…
Multi-channel algebraic scattering theory and the structure of exotic compound nuclei
本文提出了一种多道代数散射（MCAS）理论，用它从耦合道问题中找到复合核的性质。该方法定义了复合核的束缚态和共振态，即使复合核是粒子不稳定的。系统的所有共振都被发现，无论多么微弱和/或狭窄。给出了质量为7的核和{}^{15}F的能谱，以及辐射俘获截面的MCAS结果。
Our present studies has shown that the mass dependence of EVF show mass asymmetry independent behaviour. This is due the fact that with increase in asymmetry, the number of nucleon-nucleon collisions and repulsive Coulomb interactions decreases, therefore EVF increases. The increase in EVF with asymmetry is more for lighter nuclei as compared to heavier nuclei due to the further less magnitude of Coulomb repulsions in lighter nuclei as compared to heavier ones.
Multi-Nucleon Transfer Reactions and the Creation and the Evolution of the Compound Nucleus
本文提出增强的GCM方法，用于描述多核转移反应，展示与TDHF和传统GCM方法的显著差异。
Possibility of synthesizing doubly closed superheavy nucleus
本文从涨落耗散动力学出发，研究了合成双幻数超重核$^{298}114_{184}$的可能性。为了合成这种核，我们必须产生更多的丰中子复合核，因为激发复合核的中子发射。复合核$^{304}114$具有两个优点以实现高存活概率。首先，由于小的中子分离能和快速冷却，壳层校正能量恢复得很快。第二，由于中子发射，核的中子数接近双闭合壳层的中子数，核获得大的裂变势垒。由于这两种效应，$^{304}114$的存活概率直到激发能$E^{*}= 50$ MeV才降低。这些性质导致相当高的蒸发残留物截面。
The evaporation residue yields from compound nuclei $^{220}$Th formed in the $^{16}$O+$^{204}$Pb, $^{40}$Ar+$^{180}$Hf, $^{82}$Se+$^{138}$Ba, $^{124}$Sn+$^{96}$Zr reactions are analyzed to study the entrance channel effects by comparison of the capture, fusion and evaporation residue cross sections calculated by the combined dinuclear system (DNS) and advanced statistical models. The difference between evaporation residue (ER) cross sections can be related to the stages of compound nucleus formation or/and at its surviving against fission. The sensitivity of the both stages in the evolution of…
Isoscaling in statistical fragment emission in an extended compound nucleus model
基于扩展的复合核模型，研究了激发核系统统计碎片发射中的同位旋效应。从理论上预测了实验观察到的来自两个具有不同中子-质子比的相似发射源的同位素产额比$Y_i(N,Z)$的标度行为，即，证明了$Y_2/Y_1 \propto exp(αN + βZ)$的关系。从模拟结果中提取的对称能量系数$C_{sym}$为$\sim$ 27 MeV，这与现实的理论估计和最近的实验数据是一致的。详细讨论了表面熵对等标度行为的影响。结果表明，虽然表面熵增加了等标度参数$α$和$β$的数值，但对等标度行为没有定性影响，对提取的对称能系数影响很小.
We present detailed results of a theoretical investigation on the production of evaporation residue nuclei obtained in a heavy ion reaction when charged particles (proton and $α$-particle) are also emitted with the neutron evaporation along the deexcitation cascade of the formed compound nucleus. The almost mass symmetric $^{82}$Se+$^{138}$Ba reaction has been studied since there are many experimental results on individual evaporation residue (ER) cross sections after few light particle emissions along the cascade of the $^{220}$Th compound nucleus (CN) covering the wide 12--70 MeV excitation …
We present an evidence of isospin effects in nuclear fission by comparing the fission widths for reactions involving different isospin states of the same compound nucleus (CN). Yadrovsky suggested this possibility in 1975. Yadrovsky obtained the fission widths for two reaction data sets, namely $^{206}$Pb($α$,f) and $^{209}$Bi(p,f), both leading to same CN, and concluded that "a nucleus remembers the isospin value of the nuclear states leading to fission". We obtain the fission decay widths for both the $T_0+1/2$ and $T_0-1/2$ states of CN by using two appropriate reaction data sets. We then c…
We extend a conventional description of the fusion-fission fragment angular distributions by introducing the correlation between compound nucleus states carrying different total angular momenta. This correlation results in the strong anisotropy and mass-angle correlation of fission fragments for compact saddle-point nuclear shapes for which the conventional description predicts almost isotropic angular distributions. The spin off-diagonal phase relaxation timescale, $\simeq 10^{-19}$ sec, obtained from analysis of anomalous fission fragment angular distributions in $^{12}$C+$^{236}$U, $^{16}$O…
The properties of deexcitation of the same $^{220}$Th compound nucleus (CN) formed by different mass (charge) asymmetric reactions are investigated. It is demonstrated that the effective fission barrier $<B_{\rm fis}>$ value being a function of the excitation energy $E^*_{\rm CN}$ is strongly sensitive to the various orbital angular momentum $L=\ell\hbar$ distributions of CN formed with the same excitation energy $E^*_{CN}$ by the very different entrance channels $^{16}$O+$^{204}$Pb, $^{40}$Ar+$^{180}$Hf, $^{82}$Se+$^{138}$Ba and $^{96}$Zr+$^{124}$Sn. Consequently, the competition between the …
The nuclear evaporation process is reformulated by taking into account simultaneous multiparticle emission from a hot compound nucleus appearing as an intermediate state in many nuclear reaction mechanisms. The simultaneous emission of many particles is particularly relevant for high excitation energy of the compound nucleus.These channels are effectively open in competition with the single particle emissions and fission in this energy regime. Indeed, the inclusion of these channels along the decay evaporating chain shows that the yield of charged particles and occurrence of fission are affect…
In this paper a role of many-nucleon dynamics in formation of the compound $^{5}{\rm Li}$ nucleus in the scattering of protons off $α$-particles at the proton incident energies up to 20 MeV is investigated. We propose a bremsstrahlung model allowing to extract information about probabilities of formation of such nucleus on the basis of analysis of experimental cross-sections of the bremsstrahlung photons. In order to realize this approach, the model includes elements of microscopic theory and also probabilities of formation of the short-lived compound nucleus. Results of calculations of the br…
Effects of shell structure in reactions leading to the same compound nucleus or different isotopes
通过对实验得到的产生同一复合核反应的蒸发残渣激发函数的理论分析，研究了入口通道在聚变-裂变反应中的作用。在结合双核系统概念和先进统计模型的框架下，计算了xn通道的蒸发剩余物截面。导致^{216}Th^* 复合核的^{40}Ar+^{176}Hf、^{86}Kr + ^{130} Hf和^{124}Sn + ^{92}Zr反应中蒸发残留物的实验数据之间所揭示的差异，可以用所形成的复合核的不同自旋分布来解释。结果表明，对于不同的入射通道，本征熔合势垒B^* fus和势阱的大小是不同的。
Shell Effects in Quasi-fission in Reactions Forming 226Th Compound Nucleus
使用Sky3D程序模拟形成226Th复合核的两种反应，发现准裂变轨迹遵循非对称裂变谷，证实壳效应在准裂变碎片形成中起关键作用。
The model for the cold-fusion reactions related to the synthesis of super-heavy nuclei in collisions of heavy projectile-nuclei with $^{208}$Pb target nucleus is discussed. In the framework of this model the production of the compound nucleus by two paths through, the di-nuclear system and the fusion way, are taken into account simultaneously. The formation of the compound nucleus in the framework of the di-nuclear system is related to the transfer of nucleons from the light nucleus to the heavy one. The fusion way is linked to the sequential evolution of the nuclear shape from the system of c…
Pre-saddle neutron multiplicity has been calculated for several fission reactions induced by heavy ions and light particles. Experimentally, it is impossible to determine the contribution of neutrons being emitted before the saddle point and those emitted between the saddle and the scission points. Determination of the pre-saddle neutron multiplicity in our research is based on the comparison between the experimental anisotropies and those predicted by the standard saddle-point statistical model. Analysis of the results shows that the pre-saddle neutron multiplicity depends on the fission barr…
Consideration of memory of spin and parity in the fissioning compound nucleus by applying the Hauser-Feshbach fission fragment decay model to photonuclear reactions
该研究将 HF$^3$D 模型用于铀、钚光核裂变，计算瞬发与延迟中子、产额及 $γ$ 能谱，结果支持同激发能下光致裂变与中子诱发裂变相似的假设。
Fission and cluster decay of $^{76}$Sr nucleus in the ground-state and formed in heavy-ion reactions
本文计算了$^{76}Sr$处于基态或在重离子反应中形成激发态复合体系时的裂变和团簇衰变。对于$^{76}Sr$裂变假设的动态集体传质过程，预测的质量分布明显不对称，有利于$α$ -核。在一个预制的团簇模型中研究了团簇的衰变，包括从基态到基态的衰变以及从激发态到碎片的基态或激发态的衰变。
The statistical model of compound-nucleus reactions predicts that the fluctuations of the partial $γ$-decay widths for a compound-nucleus resonance are governed by the Porter-Thomas distribution (PTD), and that consequently the distribution of total $γ$-decay widths is very narrow. However, a recent experiment [Koehler, Larsen, Guttormsen, Siem, and Guber, Phys. Rev. C 88, 041305(R) (2013)] reported large fluctuations of the total $γ$-decay widths in the $^{95}$Mo$(n,γ)^{96}$Mo* reaction, contrary to this expectation. Furthermore, in recent theoretical works it was argued that sufficiently str…
Bayesian calibration of a regional optical potential and uncertainty-quantified predictions for compound nucleus reactions
本文提出区域光学势CHiRP，通过贝叶斯校准锆同位素弹性散射数据，改进复合核反应预测精度，降低不确定性，优于全局势CHUQ。
An algebraic solution of the multichannel problem applied to low energy nucleon-nucleus scattering
核子-核散射中的复合共振与靶的离散谱有关。这样的共振可以研究在一个统一的和一般的框架下，散射模型，使用sturmian展开的假设碰撞核之间的多通道相互作用。与这种扩展的多通道相互作用相关联的是代数多通道散射矩阵。固有的格林函数的矩阵结构，不仅有利于提取的亚阈值（复合核）的束缚态自旋宇称值和能量，但也很容易给出的能量和宽度的共振散射制度。我们还利用了sturmian展开方法处理非局部相互作用的能力，以考虑到由泡利原理引入的强非局部效应。作为一个例子，我们已经使用的集体模型（二阶），以定义一个多通道的潜力矩阵的低能中子C12散射允许之间的耦合0+（地面），2+（4.4389 MeV），0+（7.64 MeV）的状态。计算了该体系的代数S矩阵，预测了亚阈束缚态、截面和极化率随能量的变化。结果反映在实际测量的数据，并显示出与预期一致，可能是基于壳模型描述的目标和复合核。
It is well established that physical systems exhibit both ordered and chaotic behavior. The chaotic behavior of nanostructure such as open quantum dots has been confirmed experimentally and discussed exhaustively theoretically. This is manifested through random fluctuations in the electronic conductance. What useful information can be extracted from this noise in the conductance? In this contribution we shall address this question. In particular, we will show that the average maxima density in the conductance is directly related to the correlation function whose characteristic width is a measu…
We generalize the theory of nuclear decay and capture of Gamow that is based on tunneling through the barrier and internal oscillations inside the nucleus. In our formalism an additional factor is obtained, which describes distribution of the wave function of the $α$ particle inside the nuclear region. We discover new most stable states (called quasibound states) of the compound nucleus (CN) formed during the capture of $α$ particle by the nucleus. With a simple example, we explain why these states cannot appear in traditional calculations of the $α$ capture cross sections based on monotonic p…
Adiabatic nucleus-nucleus potential at near-barrier energies from selfconsistent calculations
本文用静态Hartree-Fock方法和Skyrme SkM ~* 相互作用计算了若干反应的绝热熔合势，并将绝热熔合势扩展到复合核区。计算的熔合势垒同意相当好的数据，尽管相当大的误差反应Q值。这表明可能用相对动能项来消除某些误差。计算的berrier高度与尖端碰撞中的熔合阻碍的想法是一致的。绝热势与冻结密度近似的结果差别很大。我们简要地讨论了相对位置和高度的融合和裂变的潜力，并推测它们可能与大Zt Zp的融合障碍。
The de-excitation of compound nuclei has been successfully described for several decades by means of statistical models. However, accurate predictions require some fine-tuning of the model parameters. This task can be simplified by studying several entrance channels, which populate different regions of the parameter space of the compound nucleus. Fusion reactions play an important role in this strategy because they minimise the uncertainty on the entrance channel by fixing mass, charge and excitation energy of the compound nucleus. If incomplete fusion is negligible, the only uncertainty on th…
During last 20 years there was revealed and published the phenomenon of the appearing of the time advance instead of the time delay at the region of a compound-nucleus resonance, distorted by the non-resonant background (in the center-of-mass (C-) system). This phenomenon is usually accompanied by a minimum in the cross section near the same energy. Here we analyze the cross section and the time delay of the nucleon-nucleus scattering in the laboratory (L-) system. In the L-system the delay-advance phenomenon does not appear. We use and concretize the non-standard analytical transformations of…
Saturation of product's exoticity in compound nuclear reactions and its role in the production of new n-deficient nuclei with radioactive projectiles
用一个新的参数--奇异性（exoticity）来表示复合核反应中产物的最大奇异性，可以清楚地看出随着复合核被放射性射弹（RIBs）制造得越来越奇异，产物的最大奇异性趋于饱和。这种饱和度的影响上的生产新的质子丰富的物种与RIBs在很宽的Z-范围内进行了讨论。
The excitation functions of capture, complete fusion, and evaporation residue formation in the $^{16}$O+$^{184}$W and $^{19}$F+$^{181}$Ta reactions leading to the same $^{200}$Pb compound nucleus has been studied theoretically to explain the experimental data showing more intense yield of evaporation residue in the former reaction in comparison with that in the latter reaction. The observed difference is explained by large capture cross section in the former and by increase of the quasifission contribution to the yield of fission-like fragments in the $^{19}$F+$^{181}$Ta reaction at large exci…
Phenomena of Time Resonances Explosions for the Compound-Clot Decays in High-Energy Nuclear Reactions
时间共振（或爆炸）现象可以解释能量的指数下降，在某些条件下，在能量强烈重叠的复合共振范围内，能量指数下降在一定程度上伴随着轻微的波动。这些共振爆炸对应于几个高度激发的非指数衰减核凝块（由几个小的抛射核子和靶组成的部分复合核）的形成。本文是理论工作者工作的继续和扩展，与传统的Izumo-Araseki时间复合核模型相比，它是时间演化方法的一个更一般的自洽版本。
Significance of the compound nucleus surface energy coefficients in the synthesis of the superheavy nuclei with $\textbf{Z=112-120}$
本文基于双核系统模型和邻近势，研究了表面能系数对 $Z=112-118$ 超重核合成的影响，确定了 $k_{s}$ 和 $\gamma_{0}$ 的最佳值，并预测了合成 $Z=119$ 和 $120$ 超重核的最优反应组合。
Alpha-nucleus potential for alpha-decay and sub-barrier fusion
α核势的参数集是通过使用α衰变半衰期和α +40 Ca，α +59 Co，α +208 Pb反应势垒周围的熔合截面的数据导出的。α-衰变半衰期的框架中获得的集群模型使用WKB近似。评价的α衰变半衰期和融合截面与数据吻合良好。α粒子和重核之间的聚变反应既可以用于形成超重核，也可以用于对所形成的复合核进行光谱研究。
The concept of compound nucleus was proposed by Niels Bohr in 1936 to explain narrow resonances observed in scattering of a slow neutron off atomic nuclei. A compound nucleus is a metastable state with a long lifetime, in which all the degrees of freedom are in a sort of thermal equilibrium. Fusion reactions are defined as reactions to form such compound nucleus by merging two atomic nuclei. Here a short description of heavy-ion fusion reactions at energies close the Coulomb barrier is presented. This includes: (i) an overview of a fusion process, (ii) a strong interplay between nuclear struct…
Quantum effects in the diffusion process to form a heavy nucleus in heavy-ion fusion reactions
讨论了描述两个核从熔合接触组态到复合核的形状演化的扩散过程中的量子效应。将量子效应理论应用到势场、质量和摩擦参数与重离子碰撞实际值相适应的情况下，我们证明了量子效应在低温下起着重要作用，这与超重元素的合成有关.
Background: Synthesis of superheavy elements (SHE) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure of the reactants. New SHE have been recently produced with doubly-magic $^{48}$Ca beams. However, SHE synthesis experiments with single-magic $^{50}$Ti beams have so far been unsuccessful. Purpose: In connection with experimental searches for $Z=117,119$ superheavy elements, we perform a theoretical study of fusion and quasifission mechanisms in $^{48}$Ca,$…
Background: At energies near the Coulomb barrier, capture reactions in heavy-ion collisions result either in fusion or in quasifission. The former produces a compound nucleus in statistical equilibrium, while the second leads to a reseparation of the fragments after partial mass equilibration without formation of a compound nucleus. Extracting the compound nucleus formation probability is crucial to predict superheavy-element formation cross-sections. It requires a good knowledge of the fragment angular distribution which itself depends on quantities such as moments of inertia and excitation e…
Cross sections for $^{40}$Ca + $α$ at low energies have been calculated from two different models and three different $α$-nucleus potentials. The first model determines the cross sections from the barrier transmission in a real nuclear potential. Second, cross sections are derived within the optical model using a complex nuclear potential. The excitation functions from barrier transmission are smooth whereas the excitation functions from the optical model show a significant sensitivity to the chosen imaginary potential. Cross sections far below the Coulomb barrier are lower from barrier transm…
Global Transmission Coefficients in Hauser-Feshbach Calculations for Astrophysics
本文讨论了在Hauser-Feshbach形式中，光学势在天体物理热核反应反应速率预测中的应用现状。特别强调的是$α$ +核电位。提出了一种预测$α$ +核电位的新方法。进一步的实验努力的动机。
Compound nucleus effective moment of inertia has been calculated for several fission reaction systems induced by nucleons, light particles, and heavy ions. Determination of this quantity for these systems is based upon the comparison between the experimental data of the fission fragment angular distributions as well as the prediction of the standard saddle-point statistical model (SSPSM). For the systems, the two cases, namely with and without neutron emission corrections were considered. In these calculations, it is assumed that all the neutrons are emitted before reaching the saddle point.It…
Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum
通过测量17种同位素的同核异能态产率比，发现其与复合核激发能无关而仅受复合核自旋影响，证明裂变碎片角动量部分源于复合核自身角动量。
We have already measured the ER excitation function of $^{48}$Ti + $^{138}$Ba reaction around the Coulomb barrier. While a detailed report of measurement of ER excitation function of $^{48}$Ti + $^{138}$Ba is available in literature, the present paper compares it with other channels forming the same compound nucleus. The experiment was performed at IUAC, New Delhi for lab energies from 189.3 to 234.4 MeV, where the ER cross sections show an abrupt fall beyond 160.03 MeV. The decrease in ER cross section is attributed to non compound nuclear reaction such as quasi-fission (QF). A comparison wit…
Presence of closed proton and/or neutron shells causes deviation from macroscopic properties of nuclei which are understood in terms of the liquid drop model. It is important to investigate experimentally the stabilizing effects of shell closure, if any, against fission. This work aims to investigate probable effects of proton shell ($Z = 82$) closure in the compound nucleus, in enhancing survival probability of the evaporation residues formed in heavy ion-induced fusion-fission reactions. Evaporation residue cross sections have been measured for the reactions $^{19}$F+$^{180}$Hf, $^{19}$F+$^{…
Microscopic study of nuclei synthesis in pycnonuclear reaction $^{12}$C + $^{12}$C in neutron stars
研究通过折叠近似和多重内部反射法，探讨了中子星密实介质中$^{12}$C + $^{12}$C反应中$^{24}$Mg核的合成过程，发现复合核形成概率在特定能量下显著增强。
An attempt to unfold the respective influence of the fusion and fission stages on typical fission observables, and namely the neutron pre-scission multiplicity, is proposed. A four-dimensional dynamical stochastic Langevin model is used to calculate the decay by fission of excited compound nuclei produced in a wide set of heavy-ion collisions. The comparison of the results from such a calculation and experimental data is discussed, guided by predictions of the dynamical deterministic HICOL code for the compound-nucleus formation time. While the dependence of the latter on the entrance-channel …
Statistical Theory of Neutron-Induced Nuclear Fission and of Heavy-Ion Fusion
本文基于随机矩阵理论和复合核反应理论，将裂变与聚变系统建模为两个由势垒连接的统计独立系统，推导出固定自旋和宇称下裂变与聚变总概率的闭式解析表达式。
Medium effects in K^+ nucleus interaction from consistent analysis of integral and differential cross sections
在500-700 MeV/c动量范围内，用“t_{eff}（rho）rho”势对K^+在几个核上的透射测量进行了自洽分析，得到了总截面的新结果。发现t_{eff}振幅的虚部随着超过阈值的平均核密度线性增加。K^+原子核光学势的密度依赖性也与最近对715 MeV/c K^+被Li ^6和C弹性散射的微分截面的测量结果吻合得很好。
We investigate different formulations of the transmission coefficient $T_c$, including the form implied by Moldauer's ``sum rule for resonance reactions'' [P.A. Moldauer, Phys. Rev. Lett. 19, 1047 (1967)], the SPRT method [G. Noguere, et al. EPJ Web Conf. 146, 02036 (2017)] and the Moldauer-Simonius form [M. Simonius, Phys. Lett. 52B, 279 (1974); P.A. Moldauer, Phys. Rev. 157, 907 (1967)]. Within these different formulations, we compute the neutron transmission coefficients in the resolved and unresolved resonance regions, allowing a direct comparison with the transmission coefficients compute…
Fission Barriers of Compound Superheavy Nuclei
裂变势垒对复合核激发能的依赖性影响着重离子聚变合成超重核的存活几率。本文用自洽核密度泛函理论研究了等熵裂变势垒。等温和等熵描述之间的关系被证明。对$^{264}$ Fm、$^{272}$ Ds、$^{278}$ 112、$^{292}$ 114和$^{312}$ 124进行了计算。对于“冷聚变”反应中产生的$^{278}$ 112周围的原子核，我们预测与“热聚变”实验中合成的$^{292}$ 114周围的原子核相比，裂变势垒随激发能的降低更快。这可以用基态温度和鞍点温度之间的差异来解释。在所研究的温度范围内，粒子气体的影响可以忽略不计。
A Microscopic T-Violating Optical Potential: Implications for Neutron-Transmission Experiments
从唯一确定的具有相同对称性的两体$ρ$ -交换相互作用出发，导出了中子-核散射的T-破坏P-守恒光学势。然后，我们从$^{165}$ Ho的中子传输实验中得到了T破坏的$ρ$ -核子耦合$\overline{g}_ρ$的极限。这些极限可能很快就会与原子电偶极矩测量的极限相竞争。
Behavior of the giant-dipole resonance in $^{120}$Sn and $^{208}$Pb at high excitation energ
计算了$^{120}$ Sn和$^{208}$ Pb的巨偶极共振（GDR）性质随激发能、角动量和复合核粒子衰变宽度的变化，并与最近的实验数据进行了比较.在$^{120}$ Sn和$^{208}$ Pb的GDR的半峰全宽的行为中观察到的差异归因于在$^{208}$ Pb中的壳修正比在$^{120}$ Sn中更强的事实，并且在低温下有利于球形。详细讨论了壳修正对自由能和转动惯量的影响。在高温下，半高宽在$^{120}$ Sn表现出由于化合物核心的蒸发宽度的影响，而这些影响被预测为$^{208}$ Pb。
Planning and interpretation of the experiments searching for the time reversal (T) and parity (P) violation in neutron reactions require values of the matrix elements of the T,P-violating nuclear forces between nuclear compound states. We calculate the root mean square values and the ratio of the matrix elements of the T,P-violating and P-violating interactions using statistical theory based on the properties of chaotic compound states and present the results in terms of the fundamental parameters in four different forms: in terms of the constants of the contact nuclear interaction, meson exch…
A variety of phenomena connected with the formation of a dinuclear complex is observed in the heavy ion collisions at low energies. The dinuclear system model allows us to analyze the experimental data and to interpret them by comparison of the partial capture, fusion and evaporation residue cross sections measured for the different reactions leading to the same compound nucleus. The comparison of theoretical and experimental values of the mass and angular distributions of the reaction products gives us a detailed information about reaction mechanism forming the observed yields. The observed v…
The time-dependent version of nuclear density functional theory, using functionals derived from Skyrme interactions, is able to approximately describe nuclear dynamics. We present time-dependent results of calculations of dipole resonances, concentrating on excitations of valence neutrons against a proton plus neutron core in the neutron-rich doubly-magic $^{132}$Sn nucleus, and results of collision dynamics, highlighting potential routes to ternary fusion, with the example of a collision of $^{48}$Ca+$^{48}$Ca+$^{208}$Pb resulting in a compound nucleus of element 120 stable against immiedate …
Using a random-matrix approach and Monte-Carlo simulations, we generate scattering matrices and cross sections for compound-nucleus reactions. In the absence of direct reactions we compare the average cross sections with the analytic solution given by the Gaussian Orthogonal Ensemble (GOE) triple integral, and with predictions of statistical approaches such as the ones due to Moldauer, to Hofmann, Richert, Tepel, and Weidenmüller, and to Kawai, Kerman, and McVoy. We find perfect agreement with the GOE triple integral and display the limits of validity of the latter approaches. We establish a c…
We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around 1 GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Liège Intranuclear Cascade Model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions types with the same parameter sets. However, no unique parameter set was obtained for the fission probability…
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