We report on the first in-beam gamma-ray spectroscopy study of the very neutron-rich nucleus 46S. The N=30 isotones 46S and 48Ar were produced in a novel way in two steps that both necessarily involve nucleon exchange and neutron pickup reactions, 9Be(48Ca,48K)X followed by 9Be(48K,48Ar+gamma)X at 85.7 MeV/u mid-target energy and 9Be(48Ca,46Cl)X followed by 9Be(46Cl,46S+gamma)X at 87.0 MeV/u mid-target energy, respectively. The results are compared to large-scale shell-model calculations in the sdpf shell using the SDPF-NR effective interaction and Z-dependent modifications.
Study of cluster structures of excited states for the light nuclei He, Li and Be in three-body photodisintegration processes. Application for the excited states of the 6He* nucleus
The fragmentation of quasi-projectiles from the nuclear reaction 40Ca + 12C at 25 MeV/nucleon was used to produce alpha-emission sources. From a careful selection of these sources provided by a complete detection and from comparisons with models of sequential and simultaneous decays, strong indications in favour of $α$-particle clustering in excited 16O, 20Ne and 24}Mg are reported.
Using a fully quantum mechanical post-form finite-range distorted-wave Born approximation theory of Coulomb breakup, I study the parallel momentum distribution of the core in the Coulomb breakup of suggested excited-state one-neutron halo nuclei considered in their different bound excited states. Narrow momentum distributions obtained in the present calculations for some cases indicate the possibilities of the excited-state halo structure in the nuclei under consideration and therefore favor the previous predictions.
A search for alpha and double beta decays of ytterbium isotopes was performed with an ultra-low background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb$_2$(C$_2$O$_4$)$_3$ powder sample was measured for 11.3~d with a total Yb exposure of 1.25 kg$\times$d. Half-life limits for $α$-decay modes of $^{168}$Yb, $^{170}$Yb, $^{171}$Yb, $^{172}$Yb, $^{173}$Yb, $^{174}$Yb and $^{176}$Yb into the first excited states have been obtained between $6\times10^{14}$ yr and $2\times10^{16}$ yr. These are the first experimental constraints of these decay modes. Doub…
The spin and parity ($J^π$) assignments in even-even nuclei were reviewed across the nuclear chart using the Evaluated Nuclear Structure Data File (ENSDF). The prevalence of 2$^+_1$ first or lowest excited states is confirmed. The properties of 0$^+_2$, 1$^-_1$, and 3$^-_1$ lowest excited states were reexamined using the ENSDF data evaluation procedures. The $J^π$ systematic trends and correlations between level quantum numbers and nuclear physics phenomena are discussed.
Parameters of Cascade Gamma-Decay of Compound-Nuclei Nd-146, Gd-156, Yb-172, Ta-182, W-184, Os-191, Th-231,233, U-239, Pu-240 from Experimental Data of Reaction $(n,γ)$
Starting from experimental studies on alpha-clustering in excited self-conjugate nuclei (from $^{16}$O to $^{28}$Si), temperature and density conditions for such a clustering are determined. Measured temperatures have been found in the range of 5.5 - 6.0 MeV whereas density values of 0.3 - 0.4 times the saturation density are deduced, i.e., 0.046 to 0.062 $fm^{-3}$. Such a density domain is also predicted by constrained self-consistent mean field calculations. These results constitute a benchmark for alpha clustering from self-conjugate nuclei in relation to descriptions of stellar evolution a…
Systematic Study of Survival Probability of Excited Superheavy Nuclei
用统计模型研究了含$100 \leq Z \leq 134$的超重核对中子发射和裂变的稳定性。特别是对这些SHN的1n沟道中抗裂变的生存概率进行了系统的研究。在目前的计算中，中子分离能和壳层修正能始终取自有限程液滴模型的计算结果，该模型预测了SHN在Z=115和N=179附近的稳定岛。事实证明，在最佳激发能下激发SHN的1n通道中计算的存活概率在Z=115和N=179附近最大化的意义上，这种稳定岛对于激发SHN持续存在。这表明1n沟道中的存活几率主要由核壳效应决定。
Particle emission from $^{40}$Ar nuclei excited in fixed-target $^{208}$Pb+$^{40}$Ar UPC at the LHC
Institute of Nuclear Physics PAN（波兰科学院核物理研究所）；Universitá degli Studi di Ferrara（费拉拉大学）；INFN Sezione di Ferrara（意大利国家核物理研究所费拉拉分部）；University of Rzeszów（热舒夫大学）
In highly dissipative collisions between heavy ions, the optimal conditions to investigate different de-excitation channels of hot nuclei such as evaporation, fission or multifragmentation are well known. One crucial issue remains the excitation energy region where fission gives way to multifragmentation. In this paper, the onset of multi-fragment exit channels is investigated in terms of sequential fission. For the first time, the dynamical approach based on solving Langevin transport equations in multidimensional collective coordinate space is used to follow the de-excitation of highly excit…
An increasing number of experimental data indicates the breaking of axial symmetry in many heavy nuclei already in the valley of stability: Multiple Coulomb excitation analysed in a rotation invariant way, gamma transition rates and energies in odd nuclei, mass predictions, the splitting of Giant Resonances (GR), the collective enhancement of nuclear level densities and Maxwellian averaged neutron capture cross sections. For the interpretation of these experimental observations the axial symmetry breaking shows up in nearly all heavy nuclei as predicted by Hartree-Fock-Bogoliubov (HFB) calcula…
We present ab initio predictions for ground and excited states of doubly open-shell fluorine and neon isotopes based on chiral two- and three-nucleon interactions. We use the in-medium similarity renormalization group, in both flow-equation and Magnus formulations, to derive mass-dependent sd valence-space Hamiltonians. The experimental ground-state energies are reproduced through neutron number N=14, beyond which a new targeted normal-ordering procedure improves agreement with data and large-scale multi-reference calculations. For spectroscopy, we focus on neutron-rich 23-26F and 24-26Ne isot…
One of the prominent decay modes of heavy nuclei which are produced in astrophysical environments at temperatures of the order of $10^9$ K is the $α$ ($^4$He) decay. Thermally enhanced $α$ decay rates are evaluated within the standard scheme of a tunneling decay where the $α$ particle tunnels through the potential barrier formed by its interaction with the daughter nucleus. Following the observation that there exist several excited levels with the possibility of an $α$ decay when the daughter nucleus is at a shell closure, we focus in particular on decays producing daughter nuclei with the neu…
采用Fayans { \it et al}的EDF方法，在自洽的TFFS中计算了100多个球奇核的基态和激发态的磁矩.我们把自己限制在有一个中子和一个质子粒子（空穴）的原子核中，这些粒子被添加到魔法或半魔法的核心中。一个简单的模型，没有相互作用的奇核子。在大多数情况下，我们分析，得到了良好的协议与实验数据。考虑了几种情况下，这种简单的模型不工作，有必要超越。对许多不稳定奇核和奇-奇核的磁矩的未知值进行了预测，其中包括60个激发态奇-奇核的磁矩。
We develop a statistical approach for the description of complex nuclei formation from dynamically produced baryons in high energy heavy-ion reactions. We consider a finite highly-excited expanding nuclear system formed after central nucleus-nucleus collisions. This system is sub-divided into primary equilibrated nucleon clusters. The final nuclei are produced after the decay of these excited clusters. By the successful comparison with the FOPI experimental data we prove the possibility of such a local equilibrium in nuclear matter with the temperature corresponding to the phase coexistence re…
Novel chiral-wobbling excitation mode in atomic nuclei
Islamic University of Science and Technology（伊斯兰科学技术大学）；University of Kashmir（克什米尔大学）；Institute of Physics (IOP)（物理研究所（IOP））；Homi Bhabha National Institute（霍米·巴巴国家研究所）；Government Degree College Shopian（肖皮安政府学位学院）；Government Degree College Kulgam（库尔加姆政府学位学院）；Shandong University（山东大学）
We have used effective reaction rates (ERR) for the helium burning reactions to predict the yield of the gamma-emitting nuclei 26Al, 44Ti, and 60Fe in core col- lapse supernovae. The variations in the predicted yields for values of the reaction rates allowed by the ERR are much smaller than obtained previously, and smaller than other uncertainties. A "filter" for supernova nucleosynthesis yields based on pre-supernova structure was used to estimate the effect of failed supernovae on the initial mass function-averaged yields; this substantially reduced the yields of all these isotopes, but the …
A recent theoretical prediction of a breaking of axial symmetry in quasi all heavy nuclei is confronted to a new critical analysis of photon strength functions of nuclei in the valley of stability. For the photon strength in the isovector giant dipole resonance (IVGDR) regime a parameterization of GDR shapes by the sum of three Lorentzians (TLO) is extrapolated to energies below and above the IVGDR. The impact of non-GDR modes adding to the low energy slope of photon strength is discussed including recent data on photon scattering and other radiative processes. These are shown to be concentrat…
