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Ogata, Kazuyuki*; Yoshida, Kazuki; Chazono, Yoshiki*
Computer Physics Communications, 297, p.109058_1 - 109058_16, 2024/04
Times Cited Count:0 Percentile:0.01(Computer Science, Interdisciplinary Applications)PIKOE is a Fortran 90 program that calculates triple- and quadruple-differential cross sections, vector analyzing powers, and momentum distributions of reaction residues, for proton-induced nucleon knockout reactions in normal and inverse kinematics. The distorted-wave impulse approximation is adopted, and the distorted waves are calculated quantum mechanically. Kinematics of the reaction particles are treated in a relativistic manner, which gives the proper asymptotics of the three-body scattering wave in the plane-wave limit.
Shim, S.-I.*; Yoshida, Kazuki; Ogata, Kazuyuki*
Journal of the Physical Society of Japan, 92(9), p.094201_1 - 094201_8, 2023/09
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)We systematically investigate the absorption effects on the cross sections of the nucleon and alpha knockout reactions. To do this, we calculate the ratio of the cross sections of the distorted-wave impulse approximation and plane-wave impulse approximation and examine its dependence on the mass number and single-particle orbital of the knocked-out particles.
Nakada, Hibiki*; Yoshida, Kazuki; Ogata, Kazuyuki*
Physical Review C, 108(3), p.034603_1 - 034603_8, 2023/09
Times Cited Count:1 Percentile:0.02(Physics, Nuclear)The description of deuteron-induced inclusive reactions has been an important subject in direct nuclear reaction studies and nuclear data science. For proton-induced inclusive processes, the semiclassical distorted wave model (SCDW) is one of the most successful models based on quantum mechanics. We improve SCDW for deuteron-induced inclusive processes. The changes in the kinematics due to the distortion effect, the refraction effect, is taken into account by the local semiclassical approximation. The calculated cross section of reasonably reproduce experimental data in the small energy-transfer region and at forward and middle angles with some exceptions. The angular distributions of the cross section are improved by including the refraction effect. The effect on the cross section is significant compared to that on the proton-induced inclusive process because of the stronger distortion effect on the deuteron.
Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Chazono, Yoshiki*; Hagen, G.*; Holt, J. D.*; et al.
Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08
Times Cited Count:1 Percentile:64.66(Astronomy & Astrophysics)Gamma decays were observed in Ca and Ca following quasi-free one-proton knockout reactions from Sc. For Ca, a ray transition was measured to be 1456(12) keV, while for Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the decays. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the and orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic Ca and potentially drives the dripline of Ca isotopes to Ca or even beyond.
Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count:2 Percentile:83.53(Astronomy & Astrophysics)Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Edagawa, Tomoatsu*; Yoshida, Kazuki; Chazono, Yoshiki*; Ogata, Kazuyuki*
Physical Review C, 107(5), p.054603_1 - 054603_7, 2023/05
Times Cited Count:4 Percentile:83.53(Physics, Nuclear)The effective polarization of the residual nucleus in the proton-induced knockout reaction is investigated within the distorted wave impulse approximation framework. The strong absorption of the emitted particle results in strong selectivity on the reaction "position" depending on the third component of the single-particle orbital angular momentum of the particle inside a nucleus, hence on the spin direction of the reaction residue.
Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.
Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04
Times Cited Count:5 Percentile:93.15(Physics, Multidisciplinary)We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.
Elekes, Z.*; Juhsz, M. M.*; Sohler, D.*; Sieja, K.*; Yoshida, Kazuki; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; Baba, Hidetada*; et al.
Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12
Times Cited Count:2 Percentile:49.92(Physics, Nuclear)The low-lying level structure of V and V was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for V while the neutron knock-out reaction provided the data for V. Four and five new transitions were determined for V and V, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed rays for each isotope could be placed in the level scheme and assigned to the decay of the first 11/2 and 9/2 levels. The (,) excitation cross sections for V were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, V could not be unambiguously placed on the island of inversion.
Chazono, Yoshiki*; Yoshida, Kazuki; Ogata, Kazuyuki*
Physical Review C, 106(6), p.064613_1 - 064613_10, 2022/12
Times Cited Count:2 Percentile:30.99(Physics, Nuclear)As a new cluster phenomenon in nuclei, a deuteron like pn cluster is in our interest. The traditional alpha cluster state can be probed by the knockout reaction analysis assuming the alpha particle is inert because the alpha particle is tightly bound. On the other hand, since deuteron is fragile, deuteron cannot be treated as an inert particle in describing the reaction. In this work, we treated the breakup and reformation of the deuteron (p-n pair) by describing the p, n, and the reaction residue in the final channel as a three body scattering state using the continuum discretized coupled channels method. We showed that the interference between the deuteron ground state and the breakup states are strong and has to be included in the deuteron knockout reaction analysis.
Enciu, M.*; Liu, H. N.*; Obertelli, A.*; Doornenbal, P.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; et al.
Physical Review Letters, 129(26), p.262501_1 - 262501_7, 2022/12
Times Cited Count:5 Percentile:65.23(Physics, Multidisciplinary)The one-neutron knockout from Ca was performed at 230 MeV/nucleon combined with prompt spectroscopy. The momentum distributions corresponding to the removal of and neutrons were measured. The cross sections are consistent with a shell closure at the neutron number , found as strong as at and in Ca isotopes from the same observables. The analysis of the momentum distributions leads to a difference of the root-mean-square radii of the neutron and orbitals of 0.61(23) fm, in agreement with the modified-shell-model prediction of 0.7 fm suggesting that the large root-mean-square radius of the orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.
Yoshida, Kazuki; Tanaka, Junki*
Physical Review C, 106(1), p.014621_1 - 014621_6, 2022/07
Times Cited Count:5 Percentile:80.72(Physics, Nuclear)Alternative to the decay lifetime measurement, we propose the proton-induced knockout reaction, (,), as a new probe for the surface formation probability of decay nuclei. Po(,)Pb reaction is described by the distorted-wave impulse approximation framework. It is shown that the Po/Po ratio of the knockout cross sections agree with that of the surface formation probabilities determined by the lifetime measurements. The result implies that the (,) cross section is a direct probe for the surface formation probability, which is an essential quantity to lead us to a complete understanding of the decay phenomena.
Koiwai, Takuma*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; Miyagi, Takayuki*; Navrtil, P.*; Ogata, Kazuyuki*; et al.
Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04
Times Cited Count:4 Percentile:74.12(Astronomy & Astrophysics)no abstracts in English
Yoshida, Kazuki; Atkinson, M. C.*; Ogata, Kazuyuki*; Dickhoff, W. H.*
Physical Review C, 105(1), p.014622_1 - 014622_7, 2022/01
Times Cited Count:2 Percentile:49.92(Physics, Nuclear)We apply the dispersive optical model (DOM) wave functions to the traditional (,) analysis and investigate the consistency of the DOM spectroscopic factor that describes the (,) cross section with the result of the (,) analysis. DOM + distorted wave impulse approximation analysis on Ca(,)K data generates a proton spectroscopic factor of 0.560, which is meaningfully smaller than the DOM value of 0.71 shown to be consistent with the (,) analysis. The inconsistency in the spectroscopic factor suggests there is urgent need for improving the description of - scattering in a nucleus.
Yoshida, Kazuki
Few-Body Systems, 62(2), p.28_1 - 28_7, 2021/06
Times Cited Count:2 Percentile:29.32(Physics, Multidisciplinary)Atomic nucleus is a quantum many-body system consisting of protons and neutrons. Nevertheless, it is known that their characteristics can be well described and understood by the few-body picture. One of such pictures is the single-particle motion of a nucleon in a mean-field potential made by all nucleons. Another one is the clustering phenomenon, clustering for example. One of the powerful probes for such states of a nucleus is the nucleon and cluster knockout reactions. In this paper, I overview how these states can be probed by the knockout reaction and discuss the present status and the future perspectives of this research field.
Juhsz, M. M.*; Yoshida, Kazuki; 77 of others*
Physical Review C, 103(6), p.064308_1 - 064308_9, 2021/06
Times Cited Count:4 Percentile:55.56(Physics, Nuclear)The level structure of V was studied for the first time by the inelastic proton scattering and the proton knock-out reaction. The comparison of the newly observed -ray transitions at 696(8) keV and 889(16) keV with our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja interaction established two excited states proposed to be the first 11/2 and 9/2 levels. The (,) excitation cross sections were analyzed by the coupled channel formalism assuming pure quadrupole as well as quadrupole+hexadecapole deformations. This resulted in large deformation parameters placing V in the island of inversion located below Ni.
Browne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Ogata, Kazuyuki*; Utsuno, Yutaka; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; Calvet, D.*; et al.
Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06
Times Cited Count:10 Percentile:74.2(Physics, Multidisciplinary)Direct proton-knockout reactions of Sc were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of Ca were investigated through -ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological inter-nucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of Sc, valence proton removals populated predominantly the ground-state of Ca. This counter-intuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.
Taniguchi, Yasutaka*; Yoshida, Kazuki; Chiba, Yohei*; Kanada-En'yo, Yoshiko*; Kimura, Masaaki*; Ogata, Kazuyuki*
Physical Review C, 103(3), p.L031305_1 - L031305_5, 2021/03
Times Cited Count:11 Percentile:86.51(Physics, Nuclear)Based on the Ti(,)Ca reaction analysis, this study reports that -particle formation in the medium-mass Ti nucleus is pronounced more compared to that expected through mean-field approximations. Moreover, the estimated average distance between the particle and residue equals approximately 4.5 fm. This result poses a challenge to describe the four nucleon correlations using microscopic nuclear models.
Juhsz, M. M.*; Elekes, Z.*; Sohler, D.*; Utsuno, Yutaka; Yoshida, Kazuki; Otsuka, Takaharu*; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Baba, Hidetada*; et al.
Physics Letters B, 814, p.136108_1 - 136108_8, 2021/03
Times Cited Count:5 Percentile:63.69(Astronomy & Astrophysics)The nuclear structure of Ar was studied by the (,2) reaction using -ray spectroscopy for the bound and unbound states. Comparing the results to our shell-model calculations, two bound and six unbound states were established. The low cross sections populating the two bound states of Ar could be interpreted as a clear signature for the presence of significant sub-shell closures at neutron numbers 32 and 34 in argon isotopes.
Chazono, Yoshiki*; Yoshida, Kenichi*; Yoshida, Kazuki; Ogata, Kazuyuki*
Physical Review C, 103(2), p.024609_1 - 024609_7, 2021/02
Times Cited Count:2 Percentile:33.7(Physics, Nuclear)The isoscalar pair is expected to emerge in nuclei. We aim to clarify the correspondence between the pairing strength in many-body calculation and the cross section of proton-induced deuteron knockout (, ) reaction on O. The radial wave function of the isoscalar pair with respect to the center of O is calculated with the energy density functional (EDF) approach and is implemented in the distorted wave impulse approximation framework. The pairing strength in the EDF calculation is varied and the corresponding change in the cross section is investigated. A clear dependence of the cross section is found. The nuclear distortion is found to make the dependence stronger. Because of the clear -coross section correspondence, the (, ) reaction will be a promising probe for the isoscalar pair in nuclei. For quantitative discussion, further modification of the description of the reaction process will be necessary.
Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
Times Cited Count:45 Percentile:96.69(Physics, Multidisciplinary)A quasifree (,) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for and orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.