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 at four different $α$-particle energies from $E_α= 10.5$ MeV to $E_α= 12$ MeV. The measured total cross-section values are in excellent agreement with previous results obtained with the activation technique, which proves the validity of the applied method. The experimental data was compared to Hauser-Feshbach calculations using the nuclear reaction code TALYS. A modified version of the semi-microscopic $α$+nucleus optical model potential OMP 3, as well as modified proton and $γ$ widths, are needed in order to obtain a good agreement between experimental data and theory. It is found, that a model using a local modification of the nuclear-physics input parameters simultaneously reproduces total cross sections of the $^{112}$Sn($α$,$γ$) and $^{112}$Sn($α$,p) reactions. The measurement of partial cross sections turns out to be very important in this case in order to apply the correct $γ$-ray strength function in the Hauser-Feshbach calculations. The model also reproduces cross-section values of $α$-induced reactions on $^{106}$Cd, as well as of ($α$,n) reactions on $^{115,116}$Sn, hinting at a more global character of the obtained nuclear-physics input.
The proton-rich isotope 68Br was discovered in secondary fragmentation reactions of fast radioactive beams. Proton-rich secondary beams of 70,71,72Kr and 70Br, produced at the RIKEN Nishina Center and identified by the BigRIPS fragment separator, impinged on a secondary 9Be target. Unambiguous particle identification behind the secondary target was achieved with the ZeroDegree spectrometer. Based on the expected direct production cross sections from neighboring isotopes, the lifetime of the ground or long-lived isomeric state of 68Br was estimated. The results suggest that secondary fragmentat…
We studied the production of neutron-rich nuclides in multinucleon transfer collisions of stable and radioactive beams in the mass range A=40-60. We first presented our experimental cross section data of projectile fragments from the reaction of 40Ar(15 MeV/nucleon) with 64Ni, 58Ni and 27Al. We then compared them with calculations based on either the deep-inelastic transfer (DIT) model or the constrained molecular dynamics (CoMD) model, followed by the statistical multifragmentation model (SMM). An overall good agreement of the calculations with the experimental data is obtained. We continued …
To get the energy spectrum distribution and cross-sections of emitted light charged particles and explore the nuclear reaction, a experiment of 80.5 MeV/u 12C beam bombarding on C, W, Cu, Au, Pb targets has been carried out at Institute of Modern Physics, Chinese Academy of Science. 30, 60 and 120 degree relative to the incident beam have been detected using three sets of telescope detectors. The results indicate that there is a tendency that heavier targets have larger double differential cross-sections and the emitted fragments are more likely to go forward. Besides, the decrease of cross-se…
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…
Validation of Product Nuclide Activity Calculations in IAEA Charged-Particle Cross Section Database for Beam Monitor Reactions
Istanbul Technical University, Energy Institute（伊斯坦布尔理工大学能源研究所）；Istanbul Technical University, Energy Institute, Nuclear Researches Division（伊斯坦布尔理工大学能源研究所核研究部）
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…
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. …
Measurement of beam-recoil observables Ox, Oz and target asymmetry for the reaction gamma p -> K Lambda
双极化（束反冲）可观测量Ox和Oz已被测量的反应γ p -> K λ从阈值生产到Egamma = 1500 MeV。这些数据是用GRAAL装置的线偏振光束获得的。尽管使用非偏振目标，也可以提取目标不对称性T的值。我们的结果分析两个等压模型倾向于确认的必要性，包括新的或鲜为人知的共振在1900兆电子伏的质量区域。
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.
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…
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…
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…
Over the last two decades transfer reactions have seen a resurgence following developments in methods to use them with exotic beams. An important step in this evolution was the ability to perform the (d,p) reaction on fission fragment beams using the inverse kinematics technique, built on the experience with light beams. There has been renewed interest in using ($^9$Be, $^8$Be) and ($^{13}$C, $^{12}$C) reactions to selectively populate single-particle like states that can be studied via their subsequent decay. These reactions have been successfully utilized in the $^{132}$Sn region. Additional…
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…
Beam-helicity asymmetry measurements in the Virtual Compton Scattering reaction in the g*N-Delta transition at Q2=0.20 (GeV/c)^2
本文报道了在Delta（1232）$ resonance at Q2=0.20 (GeV/c)2. The measurements were performed at MAMI and were carried out simultaneously with the measurement of the H(\vec{e},e'p)π^0 reaction channel. It is the lowest Q2 for which the $中H（\vec{e}，e 'p）γ反应的束流螺旋度不对称性的新测量。测量的不对称性进行了比较，并已被发现是很好地描述的色散关系（DR）计算的色散。本文用DR方法研究了数据对质子的广义极化率（GPs）和核子激发到Delta（1232）的振幅的敏感性。测量的不对称性已被发现表现出更高的灵敏度的GP，而它是建议，未来的测量更高的统计精度将提供更强的约束理论计算，并将提供有价值的洞察力对更完整的理解的GP的质子和π-N振幅。
In this review article we discuss the present status of direct nuclear reactions and the nuclear structure aspects one can study with them. We discuss the spectroscopic information we can assess in experiments involving transfer reactions, heavy-ion-induced knockout reactions and quasifree scattering with (p,2p), (p,pn), and (e,e'p) reactions. In particular, we focus on the proton-to-neutron asymmetry of the quenching of the spectroscopic strength.
Opportunities for investigations of nuclear reactions at the future nuclear physics facilities such as radioactive ion beam facilities and high-power laser facilities are considered. Post-accelerated radioactive ion beams offer possibilities for study of the role of isospin asymmetry in the reaction mechanisms at various beam energies. Fission barrier heights of neutron-deficient nuclei can be directly determined at low energies. Post-accelerated radioactive ion beams, specifically at the future facilities such as HIE-ISOLDE, SPIRAL-2 or RAON-RISP can be also considered as a candidate for prod…
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…
A novel pathway for the formation of multi-particle-multi-hole (np-mh) excited states in rare isotopes is reported from highly energy- and momentum-dissipative inelastic-scattering events measured in reactions of an intermediate-energy beam of 38Ca on a Be target. The negative-parity,complex-structure final states in 38Ca were observed following the in-beam gamma-ray spectroscopy of events in the 9Be(38Ca,38Ca+gamma)X reaction in which the scattered projectile lost longitudinal momentum of order p = 700 MeV/c. The characteristics of the observed final states are discussed and found to be consi…
Direct nuclear reactions with radioactive ion beams represent an extremely powerful tool to extend the study of fundamental nuclear properties far from stability. These measurements require pure and dense targets to cope with the low beam intensities. The $^3$He cryogenic target HeCTOr has been designed to perform direct nuclear reactions in inverse kinematics. The high density of $^3$He scattering centers, of the order of 10$^{20}$ atoms/cm$^2$, makes it particularly suited for experiments where low-intensity radioactive beams are involved. The target was employed in a first in-beam experimen…
Halo nuclei are excellent examples of few-body systems consisting of a core and weakly-bound halo nucleons. Where there is only one nucleon in the halo, as in 11Be, the many-body problem can be reduced to a two-body problem. The contribution of the 1s1/2 orbital to the ground state configuration in 11Be, characterized by the spectroscopic factor, S, has been extracted from direct reaction data by many groups over the past five decades with discrepant results. An experiment was performed at the Holifield Radioactive Ion Beam Facility using a 10Be primary beam at four different energies with the…
