Low-spin particle/hole-core excitations in $^{41,47,49}$Ca isotopes studied by cold-neutron capture reactions
S. Bottoni, N. Cieplicka-Oryńczak, S. Leoni, B. Fornal, G. Colò, P. F. Bortignon, G. Bocchi, D. Bazzacco, G. Benzoni, A. Blanc, A. Bracco, S. Ceruti, F. C. L. C… 展开作者
S. Bottoni, N. Cieplicka-Oryńczak, S. Leoni, B. Fornal, G. Colò, P. F. Bortignon, G. Bocchi, D. Bazzacco, G. Benzoni, A. Blanc, A. Bracco, S. Ceruti, F. C. L. Crespi, G. de France, E. R. Gamba, Ł. W. Iskra, M. Jentschel, U. Köster, C. Michelagnoli, B. Million, D. Mengoni, P. Mutti, Y. Niu, C. Porzio, G. Simpson, T. Soldner, B. Szpak, A. Türler, C. A. Ur, W. Urban
We present recent results on the structure of the one-valence-particle $^{41}$Ca and $^{49}$Ca, and one-valence-hole $^{47}$Ca, nuclei. The isotopes of interest were populated via the cold-neutron capture reactions $^{40}$Ca(n,$γ$), $^{48}$Ca(n,$γ$) and $^{46}$Ca(n,$γ$), respectively. The experiments were performed at the Institut Laue-Langevin, within the EXILL campaign, which employed a large array of HPGe detectors. The $γ$ decay and level schemes of these nuclei were investigated by $γ$-ray coincidence relationships, leading to the identification of 41, 10, and 6 new transitions in $^{41}$Ca, $^{47}$Ca, and $^{49}$Ca, respectively. Branching ratios and intensities were extracted for the $γ$ decay from each state, and $γ$-ray angular correlations were performed to establish a number of transition multipolarities and mixing ratios, thus helping in the spin assignment of the states. The experimental findings are discussed along with microscopic, self-consistent beyond-mean-field calculations performed with the Hybrid Configuration Mixing model, based on a Skyrme SkX Hamiltonian. The latter suggests that a fraction of the low-spin states of the $^{41}$Ca, $^{49}$Ca, and $^{47}$Ca nuclei is characterized by the coexistence of either 2p-1h and 1p-2h excitations, or couplings between single-particle/hole degrees of freedom and collective vibrations (phonons) of the doubly-magic "core".
In this paper, the production and spectroscopic investigation of Mercury and Radon isotopes was performed using complete fusion reactions neutron evaporation residues and multi-nucleon transfer reaction at the mass-separator MASHA. The MASHA setup is installed on the beam line of Cyclotron U-400M at Flerov Laboratory of Nuclear Reactions (FLNR) in Joint Institute for Nuclear Research (JINR), Dubna, Russia. The isotopes produced in complete fusion reactions 148Sm(40Ar, xn)188-xHg, 166Er(40Ar, xn)206-xRn and multi-nucleon transfer reaction 48Ca + 242Pu were passed through the magnetooptical syst…
The analysis results of the isotopic yields for products obtained in reactions of protons at energies 0.66, 1, 8.1GeV with separated tin isotopes are presented. The experimental data are compared in form of reactions of element cross sections for two targets of different isotope compositions. The scaling behaviour have been shown in the dependence of this ratios from neutron and proton composition at the reaction products. The discussion of scaling parameters allows to explain the mechanism of light and medium mass fragment production.
In the given paper the total inelastic cross-sections of the reactions of protons and deuterons on nuclear targets of enriched tin isotopes were compared. The factorization of cross-sections of reactions was discussed. Furthermore, the comparison of theoretical estimations on total inelastic cross-sections with corresponding experimental ones was made.
The reaction mechanisms best suited for the production of neutron-rich nuclei, fragmentation and fission, are discussed. Measurements of the production cross sections of reaction residues together with model calculations allow to conclude about the expected production rates of neutron-rich isotopes in future facilities.
Coherent photonuclear isotope transmutation (CPIT) produces exclusively radioactive isotopes (RIs) by coherent photonuclear reactions via E1 giant resonances. Photons to be used are medium energy photons produced by laser photons backscattered off GeV electrons. The cross sections are as large as 0.2 - 0.6 b, being independent of individual nuclides. A large fraction of photons is effectively used for the photonuclear reactions, while the scattered GeV electrons remain in the storage ring to be re-used. CPIT with medium energy photons provides specific/desired RIs with the high rate and the hi…
We treat the bremsstrahlung induced by initial electron beam in converter, and the production of a desirable radio-isotope due to the photo-nuclear reaction caused by this bremsstrahlung. By way of illustration, the yield of a number of some, the most in practice applicable, radio-isotopes is evaluated. The acquired findings persuade us that usage of modern electron accelerators offers a practicable way to produce the radio-isotopes needful nowadays for various valuable applications in the nuclear medicine.
Yields of isotopically separated light fragments and residual nuclei produced in p(1GeV)+A collisions have been analyzed. For both fragmentation and spallation reactions isotopic scaling, i.e. factorization of the isotope ratios, was observed. A generalized isoscaling for arbitrary combinations of two systems has been demonstrated. The average isotopic temperature about 4 MeV for fragmentation process was found.
The coefficients of symmetry energy term for fragments with Z=4,11,12 measured in multifragmentation reactions initiated by proton and deuteron with energy of 3.65A GeV on enriched tin isotopes 112,118,120,124Sn are determined. The dependence of isoscaling parameter on the excitation energy, the temperature of fragmenting systems and the density ratio for heavy mass products are analised.
The cross sections of 70Ge(n,2n)69Ge, 72Ge(n,2n)71Ge, 76Ge(n,gamma)77(g+0.21m)Ge, 76Ge(n,2n)75Ge nuclear reactions were measured at the energy of neutrons 13.96(6) MeV by activation method with gamma-ray and X-ray spectra studies.
Isospin effects in 12C ion induced reactions on enriched tin isotopes are investigated. The isoscaling parameter B is determined for different mass regions of product nuclei. It is shown that the isoscaling parameter is sensitive to the formation mechanism of products, and increases as the difference in the asymmetry is increasing. Using the exitatation energy obtained with the catcher technique temperatures, density ratio ro/ro0 for product nuclei in different mass regions and the values of symmetry energy coefficient for light mass regions of product nuclei for proton and deuteron induced re…
The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron (γ,xn)) and proton (photo-proton (γ,xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. Accordin…
Experimental isomeric yield ratios for the 113In(γ,n)112m,gIn reactions on the betatron B25/30 bremsstrahlung gamma beam of energy range 12-25 MeV are measured. Effective cross-sections of (γ,n)-reactions with 112mIn and 114mIn isomers output are calculated. The Penfold-Leiss and Tikhonov methods are applied to solve the Volterra integral equation. The obtained experimental cross-sections are compared with theoretical calculations using the TALYS-1.6 code.
A systematic study of the radiative proton capture reaction for all stable nickel isotopes is presented. The results were obtained using 2.0 - 6.0 MeV protons from the 11 MV tandem Van de Graaff accelerator at the University of Notre Dame. The γ-rays were detected by the NSCL SuN detector utilising the γ-summing technique. The results are compared to a compilation of earlier measurements and discrepancies between the previous data are resolved. The experimental results are also compared to the theoretical predictions obtained using the NON-SMOKER and SMARAGD codes. Based on these comparisons a…
The stellar reaction rates of radiative $α$-capture reactions on heavy isotopes are of crucial importance for the $γ$ process network calculations. These rates are usually derived from statistical model calculations, which need to be validated, but the experimental database is very scarce. This paper presents the results of $α$-induced reaction cross section measurements on iridium isotopes carried out at first close to the astrophysically relevant energy region. Thick target yields of $^{191}$Ir($α$,$γ$)$^{195}$Au, $^{191}$Ir($α$,n)$^{194}$Au, $^{193}$Ir($α$,n)$^{196m}$Au, $^{193}$Ir($α$,n)$^…
The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that highest yield for 244,246,248Cf isotopes are for the fragments with isotope of Pb (Z=82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z=80) as one fragment. In the case…
Multi-nucleon transfer reactions in $^{40}$Ca+$^{208}$Pb have been studied at several bombarding energies close to the Coulomb barrier. Light reaction products have been identified in mass and charge with a time-of-flight spectrometer. The energy spectra of the inclusive two neutron pick-up channel show a population in a narrow region of excitation energies which corresponds to the predicted energy of pairing vibration states in $^{42}$Ca.
Photonuclear reactions on stable isotopes of cadmium and tellurium at bremsstrahlung end-point energies of 10-23 MeV
Joint Institute for Nuclear Research（联合核研究所）；Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan（乌兹别克斯坦共和国科学院核物理研究所）；Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University（莫斯科国立大学斯科别尔琴核物理研究所）；Faculty of Physics of Lomonosov Moscow State University（莫斯科国立大学物理系）；Bogoliubov Laboratory of Theoretical Physics of Joint Institute for Nuclear Research（联合核研究所博戈留博夫理论物理实验室）；Dzhelepov Laboratory of Nuclear Problems of Joint Institute for Nuclear Research（联合核研究所杰列波夫核问题实验室）；Institute of Nuclear Physics, Almaty（阿拉木图核物理研究所）
As a continuation of a systematic study of reactions relevant to the astrophysical p process, the cross sections of the 74,76Se(p,gamma)75,77Br and 82Se(p,n)82Br reactions have been measured at energies from 1.3 to 3.6 MeV using an activation technique. The results are compared to the predictions of Hauser-Feshbach statistical model calculations using the NON-SMOKER and MOST codes. The sensitivity of the calculations to variations in the optical proton potential and the nuclear level density was studied. Good agreement between theoretical and experimental reaction rates was found for the react…
Isotope yields have been analyzed within the framework of a Modified Fisher Model to study the power law yield distribution of isotopes in the multifragmentation regime. Using the ratio of the mass dependent symmetry energy coefficient relative to the temperature, $a_{sym}/T$, extracted in previous work and that of the pairing term, $a_{p}/T$, extracted from this work, and assuming that both reflect secondary decay processes, the experimentally observed isotope yields have been corrected for these effects. For a given I = N - Z value, the corrected yields of isotopes relative to the yield of $…
The production of heavy neutron-rich nuclei has been investigated using cold fragmentation reactions of $^{238}$U projectiles at relativistic energies. The experiment performed at the high-resolving-power magnetic spectrometer FRS at GSI allowed to identify 45 new heavy neutron-rich nuclei: $^{205}$Pt, $^{207-210}$Au, $^{211-216}$Hg, $^{213-217}$Tl, $^{215-220}$Pb, $^{219-224}$Bi, $^{221-227}$Po, $^{224-229}$At, $^{229-231}$Rn and $^{233}$Fr. The production cross sections of these nuclei were also determined and used to benchmark reaction codes that predict the production of nuclei far from st…
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）
The cross sections and velocity distributions of projectile-like fragments from the reaction of 25 MeV/nucleon 86Kr + 64Ni have been measured using the MARS recoil separator at Texas A&M, with special emphasis on the neutron rich isotopes. Proton-removal and neutron pick-up isotopes have been observed with large cross sections. A model of deep-inelastic transfer (DIT) for the primary interaction stage and the statistical evaporation code GEMINI for the deexcitation stage have been used to describe the properties of the product distributions. The results have also been compared with the EPAX pa…
Experimental excitation functions for long-lived products in proton induced reactions were measured with the activation method in the 37-65 MeV energy range on natural holmium. Stacked foil irradiation technique and high resolution gamma spectrometry were used in order to measure cross-section data for the production of $^{161}$Er, $^{160}$Er and $^{159,157}$Dy. For comparison of the production routes of medically related $^{161}$Er and $^{160}$Er radioisotopes new experimental cross section data were deduced for the $^{162}$Er(p,x)$^{161,160}$Er and $^{162}$Er(d,x)$^{161,160}$Er reactions by …
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 …
The $γ$-process in core-collapse and/or type Ia supernova explosions is thought to explain the origin of the majority of the so-called $p$ nuclei (the 35 proton-rich isotopes between Se and Hg). Reaction rates for $γ$-process reaction network studies have to be predicted using Hauser-Feshbach statistical model calculations. Recent investigations have shown problems in the prediction of $α$-widths at astrophysical energies which are an essential input for the statistical model. It has an impact on the reliability of abundance predictions in the upper mass range of the $p$ nuclei. With the measu…
Efficient production of short-lived radioactive isotopes in inverse reaction kinematics is an important technique for various applications. It is particularly interesting when the isotope of interest is only a few nucleons away from a stable isotope. In this article production via charge exchange and stripping reactions in combination with a magnetic separator is explored. The relation between the separator transmission efficiency, the production yield, and the choice of beam energy is discussed. The results of some exploratory experiments will be presented.
Cross sections of the residual nuclei production in $^{129}$I, $^{237}$Np and $^{241}$Am target irradiated by proton beam with energy 660 MeV are measured by means of activation analysis with the use of HPGe detectors. The number of product nuclei identified amounts to 74 for $^{129}$I target, 53 for $^{237}$Np target and 80 for $^{241}$Am target. Theoretical model analysis employing eleven contemporary computer models of hadron-nuclear interactions is performed. Insufficient for practical purposes precision of modelling of the reactions under study is demonstrated. Methods for short-lived bet…
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…
Isoscaling, where ratios of isotopes emitted from two reactions exhibit an exponential dependence on the neutron and proton number of the isotope, has been observed over a variety of reactions including evaporation, strongly damped binary collision, and multifragmentation. The conditions for isoscaling to occur as well as the conditions when isoscaling fails are investigated.
The (p,$γ$) cross sections of three stable Sr isotopes have been measured in the astrophysically relevant energy range. These reactions are important for the $p$-process in stellar nucleosynthesis and, in addition, the reaction cross sections in the mass region up to 100 are also of importance concerning the $rp$-process associated with explosive hydrogen and helium burning. It is speculated that this $rp$-process could be responsible for a certain amount of $p$-nuclei in this mass region. The (p,$γ$) cross sections of $^{84,86,87}$Sr isotopes were determined using an activation technique. The…
Rare isotopes are most often studied through nuclear reactions. Nuclear reactions can be used to obtain detailed structure information but also in connection to astrophysics to determine specific capture rates. In order to extract the desired information it is crucial to have a reliable framework that describes the reaction process accurately. A few recent developments for transfer and breakup reactions will be presented. These include recent studies on the reliability of existing theories as well as effort to reduce the ambiguities in the predicted observables.
Reactions are an important tool to study nuclear structure and for extracting reactions relevant for astrophysics. In this paper we focus on deuteron induced reactions which can provide information on neutron shell evolution as well as neutron capture cross sections. We review recent work on the systematic comparison of the continuum discretized coupled channel method, the adiabatic wave approximation and the Faddeev momentum-space approach. We also explore other aspects of the reaction mechanism and discuss in detail difficulties encountered in the calculations.
One of the few p nuclei with an odd number of protons is 113In. Reaction cross sections of 113In(alpha,gamma)117Sb and 113In(alpha,n)116Sb have been measured with the activation method at center-of-mass energies between 8.66 and 13.64 MeV, close to the astrophysically relevant energy range. The experiments were carried out at the cyclotron accelerator of ATOMKI. The activities were determined by off-line detection of the decay gamma rays with a HPGe detector. Measured cross sections and astrophysical S factor results are presented and compared with statistical model calculations using three di…
The intensity interferometry is applied as a chronometer of the particle emission of hydrogen isotopes from the intermediate velocity source formed in $^{40}$Ar+$^{197}$Au reactions at 30 MeV/u. The dynamic emission order of $τ_{\rm p}>τ_{\rm d}>τ_{\rm t}$ is evidenced via the correlation functions of nonidentical particle pairs. Assuming the similar source size, the same emission order is inferred from the correlation functions of identical particle pairs, where $τ_{\rm p} \approx 100 {\rm ~fm/c}$ is extracted by the fit of Koonin-Pratt equation to p-p correlation function. Transport model si…
The reaction rates of neutron capture reactions on light nuclei are important for reliably simulating nucleosynthesis in a variety of stellar scenarios. Neutron capture reaction rates on neutron-rich C-, N-, and O-isotopes are calculated in the framework of a hybrid compound and direct capture model. The results are tabulated and compared with the results of previous calculations as well as with experimental results.
Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes.
A systematic analysis is made on the total reaction cross sections for Ne, Mg, Si, and S isotopes. The high-energy nucleus-nucleus collision is described based on the Glauber model. Using the Skyrme-Hartree-Fock method in the three-dimensional grid-space representation, we determine the nuclear density distribution for a wide range of nuclei self-consistently without assuming any spatial symmetry. The calculated total reaction cross sections consistently agree with the recent cross section data on Ne$+^{12}$C collision at 240$A$\,MeV, which makes it possible to discuss the radius and deformati…
In this work we propose to investigate the cluster structure of the excited states of nuclei produced in the photodisintegration reactions on 6 Li and 7Li targets, with three bodies (clusters and nucleons) in final state using bremsstrahlung and linear polarized beams. The analysis of the experimental data with the use of Dalitz diagrams allows to investigate 16 cluster structures of 9 isotopes of H, He and Li nuclei in four reactions of photodisintegration with the above-mentioned targets.
Spectroscopic factors have been extracted for proton rich 34Ar and neutron rich 46Ar using the (p,d) neutron transfer reaction. The experimental results show little reduction of the ground state neutron spectroscopic factor of the proton rich nucleus 34Ar compared to that of 46Ar. The results suggest that correlations, which generally reduce such spectroscopic factors, do not depend strongly on the neutron-proton asymmetry of the nucleus in this isotopic region as was reported in knockout reactions. The present results are consistent with results from systematic studies of transfer reactions b…
Muon capture isotope production (MuCIP) using negative ordinary muon capture reactions (OMC) is used to efficiently produce various kinds of nuclear isotopes for both fundamental and applied science studies. The large capture probability of muon into a nucleus, together with the high intensity muon beam, make it possible to produce nuclear isotopes in the order of 10^{9-10} per second depending on the muon beam intensity. Radioactive isotopes (RIs) produced by MuCIP are complementary to those produced by photon and neutron capture reactions and are used for various science and technology appli…
Resonant photonuclear isotope detection (RPID) is a nondestructive detection/assay of nuclear isotopes by measuring gamma rays following photonuclear reaction products. Medium-energy wideband photons of 12-16 MeV are used for the photonuclear reactions and gamma rays characteristic of the reaction products are measured by means of high-sensitivity Ge detectors. Impurities of stable and radioactive isotopes of the orders of micro-nano gr and ppm-ppb are investigated. RPID is used to study nuclear isotopes of astronuclear and particle physics interests and those of geological and historical inte…
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.
The interaction cross sections of $^{22,23}$O nuclei at 900 MeV/nucleon have been measured recently by Kanungo {\it et al.}. We show that the odd-even staggering parameter of interaction cross sections deduced from these new data agrees well with the theoretical systematics expected for the neutron separation energy of $S_n$=2.74$\pm$0.120 MeV for $^{23}$O. We also discuss briefly the energy dependence of the staggering parameter.
$^{117m}$Sn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of $^{116}$Cd metal onto high purity 12 $μ$m thick Cu backing. The average deposited thickness was 21.9 $μ$m. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil c…
The nuclear reaction induced by photon is one of the important tools in the investigation of atomic nuclei. In the reaction, a target material is bombarded by photons with high-energies in the range of gamma-ray energy range. In the bombarding process, the photons can statistically be absorbed by a nucleus in the target material. Then the excited nucleus can decay by emitting proton, neutron, alpha and light particles or photons. By performing photonuclear reaction on the target, it can be easily investigated low-lying excited states of the nuclei. In the present work, (γ, n) photonuclear reac…
Taking into account more accurately the isospin dependence of nucleon-nucleon interactions in the in-medium many-body force term of the Gogny effective interaction, new expressions for the single nucleon potential and the symmetry energy are derived. Effects of both the spin(isospin) and the density dependence of nuclear effective interactions on the symmetry potential and the symmetry energy are examined. It is shown that they both play a crucial role in determining the symmetry potential and the symmetry energy at supra-saturation densities. The improved single nucleon potential will be usef…
Radioactive isotopes produced in core-collapse supernovae (CCSNe) provide useful insights into the underlying processes driving the collapse mechanism and the origins of elemental abundances. Their study generates a confluence of major physics research, including experimental measurements of nuclear reaction rates, astrophysical modeling, and $γ$-ray observations. Here we identify the key nuclear reaction rates to the nucleosynthesis of observable radioactive isotopes in explosive silicon-burning during CCSNe. Using the nuclear reaction network calculator SkyNet and current REACLIB reaction ra…
The cross sections of the nuclear reactions induced by neutrons at $E_n$= 14.6 MeV on the isotopes of Dy, Er, Yb with emission of neutrons, proton and alpha-particle are studied by the use of new experimental data and different theoretical approaches. New and improved experimental data are measured by the neutron-activation technique. The experimental and evaluated data from EXFOR, TENDL, ENDF libraries are compared with different systematics and calculations by codes of EMPIRE~3.0 and TALYS~1.2. Contribution of pre-equilibrium decay is discussed. Different systematics for estimations of the c…
A large enhancement in the production of neutron-rich projectile residues is observed in the reactions of a 25 MeV/nucleon 86Kr beam with the neutron rich 124Sn and 64Ni targets relative to the predictions of the EPAX parametrization of high-energy fragmentation, as well as relative to the reaction with the less neutron-rich 112Sn target. The data demonstrate the significant effect of the target neutron-to-proton ratio (N/Z) in peripheral collisions at Fermi energies. A hybrid model based on a deep-inelastic transfer code (DIT) followed by a statistical de-excitation code appears to account fo…
Neutron reaction data for the set of major chromium isotopes were reevaluated from the thermal energy range up to 20 MeV. In the low energy region, updates to the thermal values together with an improved $R$-matrix analysis of the resonance parameters characterizing the cluster of large $s$-wave resonances for $^{50,53}$Cr isotopes were performed. In the intermediate and high energy range up to 20 MeV, the evaluation methodology used statistical nuclear reaction models implemented in the EMPIRE code within the Hauser-Feshbach framework to evaluate the reaction cross sections and angular distri…
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…
The cross sections for the $Z=$ 10 -- 19 with isotopes $T_{z}=-3/2$ to $-5$ in the 140$A$ MeV $^{40}$Ca + $^{9}$Be projectile fragmentation reaction have been predicted. An empirical formula based on the correlation between the cross section and average binding energy of isotope has been adopted to predict the cross section. The binding energies in the AME16, WS4, and the theoretical prediction by the spherical relativistic continuum Hartree$-$Bogoliubov theory have been used. Meanwhile, the {\sc fracs} parametrization and the modified statistical abrasion-ablation model are also used to predi…
The measurement and interpretation of isotopic yield ratios in heavy ion reactions at intermediate and high energies are discussed and the usefulness of these observables for establishing equilibrium properties and for determining thermodynamic parameters is illustrated. The examples are mainly taken from work performed with lighter projectiles at intermediate and high energies and from studies of spectator reactions at relativistic energies. As an application, the caloric curve of nuclei, as derived for Au on Au collisions, is introduced and discussed.
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…
The aim of the present work is to measure the $^{121}$Sb($α,γ$)$^{125}$I, $^{121}$Sb($α$,n)$^{124}$I, and $^{123}$Sb($α$,n)$^{126}$I reaction cross sections. The $α$-induced reactions on natural and enriched antimony targets were investigated using the activation technique. The ($α$,$γ$) cross sections of $^{121}$Sb were measured and are reported for first time. To determine the cross section of the $^{121}$Sb($α$,$γ$)$^{125}$I, $^{121}$Sb($α$,n)$^{124}$I, and $^{123}$Sb($α$,n)$^{126}$I reactions, the yields of $γ$-rays following the $β$-decay of the reaction products were measured. For the me…
Short lived $^{212,213,214}$Ra isotopes have been produced at the TRI$μ$P facility in inverse kinematics via the fusion-evaporation reaction $^{206}$Pb+$^{12}$C at 8 MeV/u. Isotopes are separated from other reaction products online using the TRI$μ$P magnetic separator. The energetic radium (Ra) isotopes at the exit of the separator were converted into low energy ions with a thermal ionizer. Ra isotopes have been identified by observing their $α$ decay and life times.
Within the Unified ternary fission model (UTFM), the alpha accompanied ternary fission of even-even $^{244-260}$Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. For the alpha accompanied ternary fission of 244^Cf isotope, the highest yield is obtained for the fragment combination 108^Ru+4^He+132^Te, which contain near doubly magic nuclei 132^Te (N=80, Z=52). In the case of 246^Cf and 248^Cf isotopes, the highest yield is obtained for the fragment combinations with near doubly magic nuclei 134^Te (N=82, Z=52) as the heavier fragment. …
The Coulomb effect hypothesis in cold fission, formerly used to interpret fluctuations in the curve of maximal total kinetic energy as a function of fragments mass, in reactions 233U(nth,f), 235U(nth,f) and 239Pu(nth,f), is confirmed by the preference for more asymmetrical charge splits observed in cold fragmentations. Several experimental results on reactions 233U(nth,f) and 235U(nth,f) show that, for two isobaric fragmentations with similar Q-values, the greater is the value of the kinetic energy of the fragments, the greater will be the probability of more asymmetric charge split.
The isotope $ {}^{99} \rm{Mo} $, the generator of $ {}^{99m} \rm{Tc} $ used for diagnostic imaging, is supplied by extracting from fission fragments of highly enriched uranium in reactors. However, a reactor-free production method of $ {}^{99} \rm{Mo} $ is searched over the world from the point of view of nuclear proliferation. Recently, $ {}^{99} \rm{Mo} $ production through a muon capture reaction was proposed and it was found that about $ 50 \, \% $ of $ {}^{100} \rm{Mo} $ turned into $ {}^{99} \rm{Mo} $ through $ {}^{100} \rm{Mo} \left( μ^-, n \right) $ reaction [arXiv:1908.08166]. However…
We explore two-particle transfer reactions as a unique probe of the occurence of shape coexistence in shape phase transitions. The (t,p) reactions to the ground state and to excited $0^+$ states are calculated for the isotope chain of even-even Zirconium isotopes starting from stable nuclei up to beyond current experimental limits. Two-particle spectroscopic factors derived from Monte Carlo Shell Model calculations are used, together with the sequential description of the two-particle transfer reaction mechanism. The calculation shows a clear signature for a shape phase transition between $^{9…
