A. I. Levon, G. Graw, Y. Eisermann, R. Hertenberger, J. Jolie, N. Yu. Shirikova, A. E. Stuchbery, A. V. Sushkov, P. G. Thirolf, H. -F. Wirth, N. V. Zamfir
备注：
35 pages in PDF, 14 figures in text and 8 figures in appendix Extended version of the paper published in Phys.Rev
The excitation spectra in the deformed nucleus 230Th were studied by means of the (p,t) reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons are measured for about 200 excitations seen in the triton spectra up to 3.3 MeV. Firm 0+ assignments are made for 16 excited states by comparison of experimental angular distributions with the calculated ones using the CHUCK code. Additional assignments are possible: relatively firm for 4 states and tentative also for 4 states. Assignments up to spin $6^+$ are made for other states. Sequences of the states are selected which can be treated as rotational bands and as multiplets of excitations. Experimental data are compared with interacting boson model IBM) and quasiparticle-phonon model (QPM) calculations.
The origin of the large $α$ particle production and incomplete fusion in reactions involving weakly-bound $α$+$x$ cluster nuclei still remains unresolved. While the (two-step) process of breakup followed by capture of the ``free" complementary fragment ($x$) is widely believed to be responsible, a few recent studies suggest the dominant role of (direct) cluster stripping. To achieve an unambiguous experimental discrimination between these two processes, a coincidence measurement between the outgoing $α$ particles and $γ$ rays from the heavy residues has been performed for the $^7$Li($α$+triton…
Background: The $^{136}$Ba isotope is the daughter nucleus in $^{136}$Xe $ββ$ decay. It also lies in a shape transitional region of the nuclear chart, making it a suitable candidate to test a variety of nuclear models. Purpose: To obtain spectroscopic information on states in $^{136}$Ba, which will allow a better understanding of its low-lying structure. These data may prove useful to constrain future $^{136}$Xe $\to$ $^{136}$Ba neutrinoless $ββ$ decay matrix element calculations. Methods: A $^{138}\mathrm{Ba}(p,t)$ reaction was used to populate states in $^{136}$Ba up to approximately 4.6 MeV…
The excitation spectra in the deformed nucleus 232U have been studied by means of the (p,t) reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for 162 excitations seen in the triton spectra up to 3.25 MeV. 0+ assignments are made for 13 excited states by comparison of experimental angular distributions with the calculated ones using the CHUCK3 code. Assignments up to spin 6+ are made for other states. Sequences of states are selected which can be treated as rotational bands. Moments of inertia have been derived fro…
The excitation spectra in the deformed nucleus 158Gd have been studied with high energy resolution by means of the (p,t) reaction using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for more than 200 excited states seen in the triton spectra up to 4.3 MeV. A number of 36 excited 0+ states (five tentative), have been assigned by comparison of experimental angular distributions with the calculated ones using the CHUCK code. Assignments for levels with higher spins are the following: 95 for 2+ states, 64 for 4+ states, 14 for 6+…
用25 MeV/核子的6 He（p，t）4 He转移反应研究了6 He基态的4 He +2n和t+t团簇.该实验是在GANIL进行的逆运动学与SPEG光谱仪耦合到MUST阵列。通过DWBA计算，包括两个中子和triton转移的转移反应的实验数据进行了分析。考虑到~ 6 He → ~ 4 He + 2n破裂通道的耦合作用，同时对~ 6 He +1H弹性散射进行了耦合离散连续通道分析，得到了极化势。对4 He +t出口势和triton顺序转移计算的影响进行了讨论。最后的计算给出了一个光谱因子接近1的4 He +2n配置的预期。对于t+t构型得到的光谱因子比理论预测小得多。
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 structure of $^{33}$Mg was investigated by means of two knockout reactions, one-neutron removal from $^{34}$Mg and one-proton removal from $^{34}$Al. Using comparative analysis of the population of observed excited states in the residual $^{33}$Mg, the nature of these states can be deciphered. In addition, the long-standing controversy about the parity of the $^{33}$Mg ground state is resolved using momentum distribution analysis, showing a clear signature for negative parity. Partial cross section measurements are compared with the results of eikonal reaction theory combined with large-sc…
Volume II of two. This document could be of interest to anyone who wants to have a comprehensive inside information about the research in nuclear physics from its early beginnings to later years. It describes highlights of my research work from the late 1950s to the late 1980s. It presents a panorama of experimental and theoretical methods used in the study of nuclear reactions (their mechanism and their application to the study of nuclear structure), the panorama ranging from simple detection techniques used in the early research to more complicated in later years, from simple theoretical int…
Volume I of two. This document could be of interest to anyone who wants to have a comprehensive inside information about the research in nuclear physics from its early beginnings to later years. It describes highlights of my research work from the late 1950s to the late 1980s. It presents a panorama of experimental and theoretical methods used in the study of nuclear reactions (their mechanism and their application to the study of nuclear structure), the panorama ranging from simple detection techniques used in the early research to more complicated in later years, from simple theoretical inte…
We report on the in-beam gamma spectroscopy of $^{102}$Sn and $^{100}$Cd produced via two-neutron removal from carbon and CH$_2$ targets at about 150 MeV/nucleon beam energy. New transitions assigned to the decay of a second 2$^+$ excited state at 2470(60) keV in $^{102}$Sn were observed. Two-neutron removal cross sections from $^{104}$Sn and $^{102}$Cd have been extracted. The enhanced cross section to the 2$^+_2$ in $^{102}$Sn populated via the $(p,p2n)$ reaction is traced back to an increase of shell-model structure overlaps, consistent with the hypothesis that the proton-induced two-deeply…
The neutron-deficient Ca isotopes continue to attract attention due to their importance for testing isospin symmetry and their relevance in capture reactions of interest for nova nucleosynthesis and the shape of light curves in Type I X-ray bursts. To date, spectroscopic information on 38,39 Ca is largely limited to data on lower-spin excited states. Here, we report in-beam γ-ray spectroscopy of complementary higher-spin, complex-structure states in 39 Ca populated in fast-beam-induced, momentum-dissipative processes leading to neutron pickup onto excited configurations of the projectile, 9 Be…
Coupling of cluster and deformed structures are important for dynamics of nuclear structure. Threshold energy has been discussed to explain cluster structures coupling to deformed states but relation between threshold energy and excitation energy has open problems. Negative-parity superdeformed (SD) states were observed by a $γ$-spectroscopy experiment in $^{35}$Cl but its detailed structure is unclear. By analyzing coupling of cluster structures in deformed states and high-lying cluster states in $^{35}$Cl, cluster structures coupling to deformed states and excitation energy of high-lying clu…
Neutron transfer reactions with fast secondary beams of $^{17}$Ne, $^{15}$O, and $^9$C have been studied with the HiRA and CAESAR arrays. Excited states of $^{18}$Ne, $^{16}$O, and $^{10}$C in the continuum have been identified using invariant-mass spectroscopy. The best experimental resolution of these states is achieved by selecting events where the decay fragments are emitted transverse to the beam direction. We have confirmed a number of spin assignments made in previous works for the negative-parity states of $^{18}$Ne. In addition we have found new higher-lying excited states in $^{16}$O…
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 com…
An extended database of experimental data is needed to address uncertainties of the nuclear-physics input parameters for Hauser-Feshbach calculations. Especially $α$+nucleus optical model potentials at low energies are not well known. The in-beam technique with an array of high-purity germanium (HPGe) detectors was successfully applied to the measurement of absolute cross sections of an ($α$,$γ$) reaction on a heavy nucleus at sub-Coulomb energies. The total and partial cross-section values were measured by means of in-beam $γ$-ray spectroscopy. Total and partial cross sections were measured a…
Knockout reactions with heavy ion targets in inverse kinematics, as well as "quasi-free" (p,2p) and (p,pn) reactions are useful tools for nuclear spectroscopy. We report calculations on \textit{ab-initio} many-body wavefunctions based on the no-core shell model to study the nucleon removal reactions in light nuclei, including beryllium, carbon, and oxygen isotopic chains, and explore the importance of using an \textit{ab-initio} method. Our study helps clarifying how the extraction of spectroscopic factors from the experiments depend on the details of the many-body wavefunctions being probed. …
Using adiabatic distorted-wave approximation (ADWA) with nonlocal optical potentials (NLOP) for $(d,p)$ transfer reactions [G.W. Bailey, N.K. Timofeyuk, and J.A. Tostevin, Phys. Rev. Lett. 117, 162502 (2016)] reported strong sensitivity to the $n$-$p$ force model. This sensitivity disappears in rigorous three-body Faddeev-type results. Some shortcomings of ADWA with NLOP are pointed out.
We observed the atomic $1s$ and $2p$ states of $π^-$ bound to ${}^{121}{\rm Sn}$ nuclei as distinct peak structures in the missing mass spectra of the ${}^{122}{\rm Sn}(d,{}^3{\rm He})$ nuclear reaction. A very intense deuteron beam and a spectrometer with a large angular acceptance let us achieve potential of discovery, which includes capability of determining the angle-dependent cross sections with high statistics. The $2p$ state in a Sn nucleus was observed for the first time. The binding energies and widths of the pionic states are determined and found to be consistent with previous experi…
The missing-mass spectroscopy of $Λ$ hypernuclei via the $(e,e^{\prime}K^{+})$ reaction has been developed through experiments at JLab Halls A and C in the last two decades. For the latest experiment, E05-115 in Hall C, we developed a new spectrometer system consisting of the HKS and HES; resulting in the best energy resolution ($E_Λ \simeq0.5$-MeV FWHM) and $B_Λ$ accuracy ($B_Λ\leq0.2$ MeV) in $Λ$-hypernuclear reaction spectroscopy. This paper describes the characteristics of the $(e,e^{\prime}K^{+})$ reaction compared to other reactions and experimental methods. In addition, the experimental…
The precise knowledge of the half-life of the reaction product is of crucial importance for a nuclear reaction cross section measurement carried out with the activation technique. The cross section of the $^{92}$Mo($α$,n)$^{95}$Ru reaction was measured recently using this experimental approach. The preliminary results indicated that the literature half-life of $^{95}$Ru, derived about half a century ago, is overestimated. Therefore, the half-lives of $^{95}$Ru and its daughter isotope $^{95}$Tc and $^{95m}$Tc have been measured with high precision using $γ$-spectroscopy. The results are t$_{1/…
The structure of $^{35}$P was studied with a one-proton knockout reaction at88~MeV/u from a $^{36}$S projectile beam at NSCL. The $γ$ rays from thedepopulation of excited states in $^{35}$P were detected with GRETINA, whilethe $^{35}$P nuclei were identified event-by-event in the focal plane of theS800 spectrograph. The level scheme of $^{35}$P was deduced up to 7.5 MeV using$γ-γ$ coincidences. The observed levels were attributed to protonremovals from the $sd$-shell and also from the deeply-bound $p\_{1/2}$ orbital.The orbital angular momentum of each state was derived from the comparisonbetw…
Theoretical models of low-energy (d,p) single-neutron transfer reactions are a crucial link between experimentation, nuclear structure and nuclear astrophysical studies. Whereas reaction models that use local optical potentials are insensitive to short-range physics in the deuteron, we show that including the inherent nonlocality of the nucleon-target interactions and realistic deuteron wave functions generates significant sensitivity to high n-p relative momenta and to the underlying nucleon-nucleon interaction. We quantify this effect upon the deuteron channel distorting potentials within th…
We report on the first in-beam $γ$-ray spectroscopy of the proton-dripline nucleus $^{40}$Sc using two-nucleon pickup onto an intermediate-energy rare-isotope beam of $^{38}$Ca. The $^{9}$Be($^{38}$Ca,$^{40}$Sc$+γ$)X reaction at 60.9 MeV/nucleon mid-target energy selectively populates states in $^{40}$Sc for which the transferred proton and neutron couple to high orbital angular momentum. In turn, due to angular-momentum selection rules in proton emission and the nuclear structure and energetics of $^{39}$Ca, such states in $^{40}$Sc then exhibit $γ$-decay branches although they are well above…
In order to provide data for the simulation of the astrophysical $γ$-process, the cross section measurement of the $^{124}$Xe(p,$γ$)$^{125}$Cs reaction is in progress at MTA Atomki using the activation technique. Precise information on the decay characteristics of the reaction products is of crucial importance for measurements carried out using this method. The half-lives of the produced $^{125}$Cs and its daughter $^{125}$Xe are published in previous works, but with large uncertainties and ambiguous values. To make these nuclear parameters more precise, the half-lives have been re-measured wi…
We review the last two decades of using photon beams to measure the production of mesons, and in particular the information that can be obtained on the spectrum of light, non-strange baryons. This is a compendium of experimental results, which should be used as a complement to theoretical reviews of the subject. Lists of data sets are given, together with a comprehensive set of references. An indication of the impact of the data is presented with a summary of the results.
The two-body core+$2n$ cluster structure was implemented to describe the two-neutron halo nucleus $^{\mathrm{14}}\mathrm{Be}$, where the core$^{\mathrm{12}}\mathrm{Be}$ was assumed inert and at ground state and the dineutron was assumed at pure $2S_0$ state. Based on such a structure the three-body continuum-discretized coupled-channel (CDCC) calculation was successfully used to deal with the $^{\mathrm{14}}\mathrm{Be}$ breakup reactions of $^{\mathrm{14}}\mathrm{Be}+^{\mathrm{12}}\mathrm{C}$ at 68~MeV/nucleon and $^{\mathrm{14}}\mathrm{Be}+ $Pb at 35~MeV/nucleon.Consequently, we modeled the k…
We point out that after presenting our results on high $n$-$p$ momentum sensitivity of the $(d,p)$ cross sections in [Phys. Rev. Lett. 117 162502 (2016)] the last paragraph of our Letter refers to a need of going beyond the leading order of Weinberg state treatment. This task could be achieved by using any method that can provide exact solution of the three-body problem. Deltuva [arXiv:1806.00298] uses Faddeev equations to study the NN-model dependence of the $(d,p)$ cross sections. His results are consistent with a new study performed at Surrey which is undergoing a reviewing process at Physi…
Recent results on the study of light-quark baryons with the ANL-Osaka dynamical coupled-channels (DCC) approach are presented, which contain the N* and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the Lambda* and Sigma* spectroscopy via the analysis of K- p reactions. A recent application of our DCC approach to neutrino-nucleon reactions in the resonance region is also presented.
Observation of Tensor-Driven High-Momentum Neutrons in ${}^{16}$O via ($p,d$) Reactions and Zero-Degree Deuteron Momentum Spectroscopy
School of Physics, Beihang University（北京航空航天大学物理学院）；Research Center for Nuclear Physics, Osaka University（大阪大学核物理研究中心）；State Key Laboratory of Heavy Ion Science and Technology, Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所重离子科学和技术国家重点实验室）；School of Nuclear Science and Technology, University of Chinese Academy of Sciences（中国科学院大学核科学与技术学院）；Joint Department for Nuclear Physics, Lanzhou University and Institute of Modern Physics, Chinese Academy of Sciences（兰州大学与中国科学院近代物理所联合核物理系）；Nishina Center for Accelerator-Based Science, RIKEN（理化学研究所仁科加速器科学中心）；High Energy Nuclear Physics Laboratory, RIKEN（理化学所高能核物理实验室）
States in the $N=28$ nucleus $^{46}$Ar have been studied by a two-neutron transfer reaction at REX-ISOLDE (CERN). A beam of radioactive $^{44}$ at an energy of 2.16~AMeV and a tritium loaded titanium target were used to populate $^{46}$ by the t($^{44}$,p) two-neutron transfer reaction. Protons emitted from the target were identified in the T-REX silicon detector array. The excitation energies of states in $^{46}$ have been reconstructed from the measured angles and energies of recoil protons. Angular distributions for three final states were measured and based on the shape of the differential…
Background: The nucleus $^{32}$Mg ($N=20$ and $Z=12$) plays a central role in the so-called "island of inversion" where in the ground states $sd$-shell neutrons are promoted to the $fp$-shell orbitals across the shell gap, resulting in the disappearance of the canonical neutron magic number $N=20$. Purpose: The primary goals of this work are to extend the level scheme of $^{32}$Mg, provide spin-parity assignments to excited states, and discuss the microscopic structure of each state through comparisons with theoretical calculations. Method: In-beam $γ$-ray spectroscopy of $^{32}$Mg was perform…
The missing mass spectroscopy of $Ξ^{-}$ hypernuclei with the $(K^{-},K^{+})$ reaction is planned to be performed at the J-PARC K1.8 beam line by using a new magnetic spectrometer, Strangeness $-2$ Spectrometer (S-2S). A $Č$cerenkov detector with a radiation medium of pure water (refractive index of 1.33) is designed to be used for on-line proton rejection for a momentum range of 1.2 to 1.6 GeV/$c$ in S-2S. Prototype water $Č$erenkov detectors were developed and tested with positron beams and cosmic rays to estimate their proton-rejection capability. We achieved an average number of photoelect…
