Detailed low-spin spectroscopy of 65Ni via neutron capture reaction
C. Porzio, C. Michelagnoli, N. Cieplicka-Orynczak, M. Sferrazza, S. Leoni, B. Fornal, Y. Tsunoda, T. Otsuka, S. Bottoni, C. Costache, F. C. L. Crespi, L. W. Isk… 展开作者
C. Porzio, C. Michelagnoli, N. Cieplicka-Orynczak, M. Sferrazza, S. Leoni, B. Fornal, Y. Tsunoda, T. Otsuka, S. Bottoni, C. Costache, F. C. L. Crespi, L. W. Iskra, M. Jentschel, F. Kandzia, Y. -H. Kim, U. Koester, N. Marginean, C. Mihai, P. Mutti, A. Turturica
An extended investigation of the low-spin structure of the $^{65}$Ni nucleus was performed at the Institut Laue-Langevin, Grenoble, via the neutron capture reaction $^{64}$Ni(n,$γ$)$^{65}$Ni, using the FIPPS HPGe array. The level scheme of $^{65}$Ni was significantly expanded, with 2 new levels and 87 newly found transitions. Angular correlation analyses were also performed, allowing us to assign spins and parities for a number of states, and to determine multipolarity mixing ratios for selected $γ$ transitions. The low-energy part of the experimental level scheme (up to about 1.4 MeV) was compared with Monte Carlo Shell Model calculations, which predict spherical shapes for all states, apart from the 9/2$^+$ and the second excited 1/2$^-$ states of oblate deformation.
The 15N(p,n) reaction is a promising candidate for the production of monoenergetic neutrons with energies of up to 5.7 MeV at the facilities where the T(p,n)3He reaction cannot be used. The characteristic properties of this reaction were studied focusing on its suitability as a source of monoenergetic neutrons for the measurement of differential scattering cross sections in the neutron energy range of 2 MeV to 5 MeV. For this purpose differential and integral cross sections were measured and the choice of optimum target conditions was investigated. The reaction has already been used successful…
The average prompt-fission-neutron multiplicity $\barν$ is of significance in the areas of nuclear theory, nuclear nonproliferation, and nuclear energy. In this work, the surrogate-reaction method has been used for the first time to indirectly determine $\barν$ for $^{239}$Pu($n$,$f$) via $^{240}$Pu($α$,$α^{\prime}f$) reactions. A $^{240}$Pu target was bombarded with a beam of 53.9-MeV $α$ particles. Scattered $α$ particles, fission products, and neutrons were measured with the NeutronSTARS detector array. Values of $\barν$ were obtained for a continuous range of equivalent incident neutron en…
$^{1}S_{0}$ \textit{nn}-scattering length has been measured in the \textit{nd}-breakup reaction at 60 MeV. The experiment was performed in the final state interaction geometry with registration of all three secondary particles. The scattering length $a_{nn} = -16.3 \pm 0.5$~fm was obtained from a comparison of the experimental dependence of the \textit{nd}-breakup yield on the relative energy of \textit{nn}-pair with the simulation results. An analysis of this value of scattering length together with the data obtained in other experiments on \textit{nd}- and \textit{dd}-breakup confirms the hy…
The neutron-capture reaction plays a critical role in the synthesis of the elements in stars and is important for societal applications including nuclear power generation and stockpile-stewardship science. However, it is difficult - if not impossible - to directly measure neutron capture cross sections for the exotic, short-lived nuclei that participate in these processes. In this Letter we demonstrate a new technique which can be used to indirectly determine neutron-capture cross sections for exotic systems. This technique makes use of the $(d,p)$ transfer reaction, which has long been used a…
PINO - a tool for simulating neutron spectra resulting from the 7Li(p,n) reaction
7 Li（p，n）反应与3.7 MV的Van de Graaff加速器相结合，在FZK常规使用，以进行激活以及keV区域中子的飞行时间测量。计划中的具有更高质子电流的新装置（如SARAF和FRANZ）以及液体锂靶技术的可用性将引发这种方法的复兴。详细了解中子能谱不仅在实验计划阶段很重要，而且在活化实验分析过程中也很重要。因此，基于蒙特卡罗的程序PINO（质子在中子出）的开发，它允许考虑设置的几何形状和质子能量分布的中子谱的模拟。
A ThO$_{2}$ sample and a nickel activation foil were irradiated in the leakage neutron field of CFBR-II reactor. The activities of the activation products were measured after irradiation to obtain the reaction rates. The normalized reaction rates were also calculated based on the ENDF/B-VII.1, CENDL-3.1, JENDL-4.0, BROND-2.2 databases. The experimental reaction rate ratio is 4.37 with an uncertainty of 3.9\% which is coincident with each of the ratios calculated based on the ENDFB-VII. 1, JENDL-4.0, BROND-2.2 databases, but is 11.2\% larger than that based on CENDL-3.1 database.
Reliable neutron-induced reaction cross sections of unstable nuclei are essential for nuclear astrophysics and applications but their direct measurement is often impossible. The surrogate-reaction method is one of the most promising alternatives to access these cross sections. In this work, we successfully applied the surrogate-reaction method to infer for the first time both the neutron-induced fission and radiative-capture cross sections of 239Pu in a consistent manner from a single measurement. This was achieved by combining simultaneously-measured fission and gamma-emission probabilities f…
Observation of hidden nuclear reactions on fast neutron-irradiated Lu isotopes
International Nuclear Safety Center of Ukraine of Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学乌克兰国际核安全中心）；Department of Nuclear and High Energy Physics, Faculty of Physics, Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学物理学院核与高能物理系）；HUN-REN Institute for Nuclear Research (HUN-REN ATOMKI)（匈牙利研究与创新网络原子核研究所）
Effect of neutron composition and excitation energy on the primary fragment yield distribution in multifragmentation reaction
本文研究了30、40和47 MeV/核子下$^{58}$ Fe + $^{58}$ Ni和$^{58}$ Fe + $^{58}$ Fe反应多重碎裂中初级和次级碎片产额分布的同位素性质。从所观察到的碎片产额分布的减少的中子和质子密度显示初级碎片产额分布经历强烈的次级去激发。在最低的激发能和最小的中子-质子比下，该效应较小，而在较高的激发能和较高的中子-质子比下，该效应变大。从约化中子密度推导出的初级碎片的对称能明显低于饱和密度下正常核的对称能，表明碎片是高度激发的，并在约化密度下形成。此外，还观察到对称能随着激发能的增加而缓慢减小。观察到的效果解释使用统计多重碎裂模型。
The one neutron knock-out reaction $^1$H($^{20}$C,$^{19}$C$γ$) was studied at RIKEN using the DALI2 array. A $γ$ ray transition was observed at 198(10) keV. Based on the comparison between the experimental production cross section and theoretical predictions, the transition was assigned to the decay of the 3/2$_1^+$ state to the ground state.
The quest for the origin of the chemical elements, which we find in our body, in our planet (Earth), in our star (Sun), or in our galaxy (Milky Way) could only be resolved with a thorough understanding of the nuclear physics properties of stable and unstable atomic nuclei. While the elements until iron are either created during the big bang or during fusion reactions in stars, most of the elements heavier than iron are produced via neutron-induced reactions. Therefore, neutron capture cross sections of stable and unstable isotopes are important. So far, time-of-flight or activation methods hav…
Accurate multiplicities of prompt fission neutrons emitted in neutron-induced fission on a large energy range are essential for fundamental and applied nuclear physics. Measuring them to high precision for radioactive fissioning nuclides remains, however, an experimental challenge. In this work, the average prompt-neutron multiplicity emitted in the 239Pu(n,f) reaction was extracted as a function of the incident-neutron energy, over the range 1-700~MeV, with a novel technique, which allowed to minimize and correct for the main sources of bias and thus achieve unprecedented precision. At low en…
Influence of secondary neutrons on alpha-particle induced reaction cross section measurement below the Coulomb barrier
International Atomic Energy Agency（国际原子能机构）；The University of Osaka（大阪大学）；RIKEN（理化学研究所）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构）；The Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）；Hokkaido University（北海道大学）
A new method is proposed to deduce the neutron radii of neutron-rich nuclei. This method requires measuring the reaction cross sections of both the neutron-rich nucleus and its stable isotope at the same energy on a proton target. Using this method and the available experimental data of $^{12,22}$C + $p$ and $^{9,14}$Be + $p$ at 40$A$ MeV, the neutron radii of $^{22}$C and $^{14}$Be have been deduced for the first time.
The relative importance of neutron transfer and breakup process in reaction around Coulomb barrier energies have been studied for the $^{7}$Li+$^{124}$Sn system. Coupled channel calculations have been performed to understand the one neutron stripping and pickup cross sections along with the breakup in the $^{7}$Li+$^{124}$Sn system. The systematics of one and two neutron striping and pickup cross sections with $^7$Li projectile on several targets show an approximate universal behaviour that have been explained by a simple model. Complete reaction mechanism have been studied by comparing the re…
Background: Eclipse effect of the neutron and proton in a deuteron target is essential to correctly describe high-energy deuteron scattering. The nucleus-deuteron scattering needs information not only on the nucleus-proton but also the nucleus-neutron interaction, for which no direct measurement of the nucleus-neutron cross sections is available for unstable nuclei. Purpose: We systematically evaluated the total reaction cross sections by a deuteron target to explore the feasibility of extracting the nucleus-neutron interaction from measurable cross sections. Methods: High-energy nucleus-deute…
We investigate the contributions of various reaction channels to the interaction, reaction, charge-changing and neutron-changing cross sections. The goal is to investigate the relation between microscopic interactions and the symmetry energy component of the equation of state (EoS) of interest for the structure of neutron stars. We have made a comparison of the neutron skins extracted from diverse experimental techniques with those obtained with Hartree-Fock-Bogoliubov calculations with 23 Skyrme and with 8 density-dependent interactions used in the relativistic mean field method. We have show…
Probabilities for two-neutron transfer reactions, $P_{\rm 2n}$, are often discussed in comparison with the square of the corresponding probabilities for one-neutron transfer process, $(P_{\rm 1n})^2$, implicitly assuming that $(P_{\rm 1n})^2$ provides the probability of two-neutron transfer reactions in the absence of the pairing correlation. We use a schematic coupled-channels model, in which the transfers are treated as effective inelastic channels, and demonstrate that this model leads to $P_{\rm 2n}=(P_{\rm 1n})^2/4$, rather than $P_{\rm 2n}=(P_{\rm 1n})^2$, in the pure sequential limit. W…
Neutrons can induce background events in underground experiments looking for rare processes. Neutrons in a MeV range in deep underground laboratories are produced in spontaneous fission processes and ($α,n$) reactions. A number of computer codes are available to calculate cross-sections of ($α,n$) reactions, branching ratios to various states and neutron yields. We have used the SOURCES4 code to calculate neutron yields and energy spectra with input cross-sections and branching ratios taken from experimental data and calculations based on EMPIRE2.19/3.2.3 and TALYS1.9. We report here a compari…
We discuss the possibility to build a neutron target for nuclear reaction studies in inverse kinematics utilizing a storage ring and radioactive ion beams. The proposed neutron target is a specially designed spallation target surrounded by a large moderator of heavy water (D$_2$O). We present the resulting neutron spectra and their properties as a target. We discuss possible realizations at different experimental facilities.
Monte Carlo algorithm for calculating pre-neutron fragment mass and kinetic energy distributions from measurements using the 2E Technique for reaction 235U(nth, f)
A Neutron Time-Of-Flight (NTOF) spectrometer based on Heavy Ion Research Facility in Lanzhou (HIRFL) is developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production double-differential cross sections and the available experimental one, a detailed description of NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established. The comparisons of the test beam neutron spectra with those of GEANT4 s…
We report results of fast neutron response in plastic scintillator (PS) bars from deuterium-deuterium (D-D) and deuterium-tritium (D-T) reactions using Purnima Neutron Generator Facility, BARC, Mumbai. These measurements are useful in context of Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) detection, an array of 10x10 PS bars, used to measure reactor anti-neutrinos through inverse beta decay (IBD) signal. ISMRAN detector, an above-ground experiment close to the reactor core (~13m), deals with an active fast neutron background inside the reactor hall. A good understanding of fa…
Background: Multi-nucleon transfer reactions have recently attracted attention as a possible path to the synthesis of new neutron-rich heavy nuclei. Purpose: We study transfer reactions involving massive nuclei with the intention of understanding if the semi-classical model GRAZING coupled to an evaporation and fission competition model can satisfactory reproduce experimental data on transfer reactions in which fission plays a role. Methods: We have taken the computer code GRAZING and have added fission competition to it (GRAZING-F) using our current understanding of $Γ_n/Γ_f$, fission barrier…
Mono-energetic gamma-beams ($Δ\sim 10$ eV) based on thermal neutron capture, in a nuclear reactor, using the V(n, $γ$) and Fe(n,$γ$) reactions, were utilized for generating fast neutron sources from lead and thallium respectively, via the $^{207}$Pb($γ$,n) and $^{205}$Tl($γ$,n) reactions. It so happened that one of the incident gamma-lines of the V source, E$_γ$ = 7163 keV, photoexcites by chance a resonance level in $^{207}$Pb, which emits neutrons at an energy of 423 keV. In a similar manner, the incident $γ$-line at E$_γ$ = 7646 keV of the Fe(n, $γ$) source photoexcites by chance a resonanc…
