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Journal Articles

"Southwestern" boundary of the $$N = 40$$ island of inversion; First study of low-lying bound excited states in $$^{59}$$V and $$^{61}$$V

Elekes, Z.*; Juh$'a$sz, 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:0 Percentile:0.02(Physics, Nuclear)

The low-lying level structure of $$^{59}$$V and $$^{61}$$V was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for $$^{61}$$V while the neutron knock-out reaction provided the data for $$^{59}$$V. Four and five new transitions were determined for $$^{59}$$V and $$^{61}$$V, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed $$gamma$$ 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 ($$p$$,$$p'$$) excitation cross sections for $$^{61}$$V were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, $$^{61}$$V could not be unambiguously placed on the island of inversion.

Journal Articles

Extended $$p_{3/2}$$ neutron orbital and the $$N = 32$$ shell closure in $$^{52}$$Ca

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:0 Percentile:0(Physics, Multidisciplinary)

The one-neutron knockout from $$^{52}$$Ca was performed at $$sim$$230 MeV/nucleon combined with prompt $$gamma$$ spectroscopy. The momentum distributions corresponding to the removal of $$1f_{7/2}$$ and $$2p_{3/2}$$ neutrons were measured. The cross sections are consistent with a shell closure at the neutron number $$N = 32$$, found as strong as at $$N = 28$$ and $$N = 34$$ 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 $$1_{f7/2}$$ and $$2p_{3/2}$$ 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 $$2p_{3/2}$$ orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.

Journal Articles

A First glimpse at the shell structure beyond $$^{54}$$Ca; Spectroscopy of $$^{55}$$K, $$^{55}$$Ca, and $$^{57}$$Ca

Koiwai, Takuma*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; Miyagi, Takayuki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; et al.

Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04

 Times Cited Count:2 Percentile:77.37(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Development and testing of a delayed gamma-ray spectroscopy instrument utilizing Cf-252 neutrons evaluated for nuclear safeguards applications

Rodriguez, D.; Abbas, K.*; Koizumi, Mitsuo; Nonneman, S.*; Rossi, F.; Takahashi, Tone

Nuclear Instruments and Methods in Physics Research A, 1014, p.165685_1 - 165685_10, 2021/10

 Times Cited Count:2 Percentile:47.5(Instruments & Instrumentation)

Journal Articles

Investigation of the ground-state spin inversion in the neutron-rich $$^{47,49}$$Cl isotopes

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; G$'o$mez-Ramos, M.*; et al.

Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10

AA2021-0468.pdf:1.29MB

 Times Cited Count:2 Percentile:47.5(Physics, Nuclear)

no abstracts in English

Journal Articles

Improved experimental evaluation and model validation of a $$^{252}$$Cf irradiator for delayed gamma-ray spectroscopy applications

Tohamy, M.*; Abbas, K.*; Nonneman, S.*; Rodriguez, D.; Rossi, F.

Applied Radiation and Isotopes, 173, p.109694_1 - 109694_7, 2021/07

 Times Cited Count:5 Percentile:79.86(Chemistry, Inorganic & Nuclear)

Journal Articles

Pairing forces govern population of doubly magic $$^{54}$$Ca from direct reactions

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:5 Percentile:61.32(Physics, Multidisciplinary)

Direct proton-knockout reactions of $$^{55}$$Sc were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of $$^{54}$$Ca were investigated through $$gamma$$-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 $$^{55}$$Sc, valence proton removals populated predominantly the ground-state of $$^{54}$$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.

Journal Articles

Evaluation of high-energy delayed gamma-ray spectra dependence on interrogation timing patterns

Rodriguez, D.; Bogucarska, T.*; Koizumi, Mitsuo; Lee, H.-J.; Pedersen, B.*; Rossi, F.; Takahashi, Tone; Varasano, G.*

Nuclear Instruments and Methods in Physics Research A, 997, p.165146_1 - 165146_13, 2021/05

 Times Cited Count:1 Percentile:28.01(Instruments & Instrumentation)

Journal Articles

Model design of a deuterium-deuterium neutron generator moderator and evaluation for delayed gamma-ray nondestructive assay for safeguards verification

Rossi, F.; Koizumi, Mitsuo; Rodriguez, D.

Journal of Nuclear Science and Technology, 58(3), p.302 - 314, 2021/03

 Times Cited Count:4 Percentile:54.77(Nuclear Science & Technology)

Journal Articles

First spectroscopic study of $$^{51}$$Ar by the ($$p$$,2$$p$$) reaction

Juh$'a$sz, 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

AA2020-0747.pdf:0.83MB

 Times Cited Count:2 Percentile:47.5(Astronomy & Astrophysics)

The nuclear structure of $$^{51}$$Ar was studied by the ($$p$$,2$$p$$) reaction using $$gamma$$-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 $$^{51}$$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.

Journal Articles

$$N$$ = 32 shell closure below calcium; Low-lying structure of $$^{50}$$Ar

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Men$'e$ndez, J.*; Ogata, Kazuyuki*; Schwenk, A.*; Shimizu, Noritaka*; Simonis, J.*; et al.

Physical Review C, 102(6), p.064320_1 - 064320_9, 2020/12

AA2020-0748.pdf:0.75MB

 Times Cited Count:7 Percentile:73.84(Physics, Nuclear)

Low-lying excited states in the $$N$$ = 32 isotope $$^{50}$$Ar were investigated by in-beam $$gamma$$-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3$$^{-}$$ state. The level scheme built using $$gamma$$ $$gamma$$ coincidences was compared to shell-model calculations in the $$sd-pf$$ model space and to ${it ab initio}$ predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2$$^{+}$$ states, while the previously proposed 4$$^{+}_{1}$$ state could also correspond to a 2$$^{+}$$ state.

Journal Articles

Utilizing nuclear data in delayed gamma-ray spectroscopy inverse Monte Carlo analysis

Rodriguez, D.; Abbas, K.*; Crochemore, J.-M.*; Koizumi, Mitsuo; Nonneman, S.*; Pedersen, B.*; Rossi, F.; Seya, Michio*; Takahashi, Tone

EPJ Web of Conferences, 239, p.17005_1 - 17005_5, 2020/09

 Times Cited Count:0 Percentile:0.1

Journal Articles

Utilizing PUNITA experiments to evaluate fundamental delayed gamma-ray spectroscopy interrogation requirements for nuclear safeguards

Rodriguez, D.; Koizumi, Mitsuo; Rossi, F.; Seya, Michio; Takahashi, Tone; Bogucarska, T.*; Crochemore, J.-M.*; Pedersen, B.*; Takamine, Jun

Journal of Nuclear Science and Technology, 57(8), p.975 - 988, 2020/08

 Times Cited Count:3 Percentile:44.39(Nuclear Science & Technology)

Journal Articles

Corrigendum to "Model design of a compact delayed gamma-ray moderator system using $$^{252}$$Cf for safeguards verification measurements" [Appl. Radiat. Isot. 148C (2019) 114-125]

Rodriguez, D.; Rossi, F.; Takahashi, Tone; Seya, Michio*; Koizumi, Mitsuo

Applied Radiation and Isotopes, 159, P. 109083_1, 2020/05

 Times Cited Count:0 Percentile:1.49(Chemistry, Inorganic & Nuclear)

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:23 Percentile:95.85(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

AA2019-0306.pdf:0.57MB

 Times Cited Count:37 Percentile:92.33(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Delayed gamma-ray spectroscopy for nuclear material analysis, 2; Design of a practical system with DD neutron generator

Rossi, F.; Rodriguez, D.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo

Proceedings of INMM 60th Annual Meeting (Internet), 7 Pages, 2019/07

Journal Articles

Model design of a compact delayed gamma-ray moderator system using $$^{252}$$Cf for safeguards verification measurements

Rodriguez, D.; Rossi, F.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo

Applied Radiation and Isotopes, 148, p.114 - 125, 2019/06

 Times Cited Count:5 Percentile:56.26(Chemistry, Inorganic & Nuclear)

Journal Articles

Delayed gamma-ray spectroscopy, 2; Design study of moderator for a practical system

Rossi, F.; Rodriguez, D.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (CD-ROM), 3 Pages, 2018/11

This paper (presentation) reports on the design study for seeking compactness of moderator (and reflector) structure for the Delayed Gamma-ray Spectroscopy Non Destructive Assay system to be applied for verification of fissile isotopic (Pu-239, Pu-241 and U-235) composition ratio in High Radioactive Nuclear Material sample such as dissolved solution of reprocessing facility. We first investigated advantages and disadvantages of using different compact neutron sources as DT and DD neutron generators. This led us to the conclusion of using DD sources to achieve a compact (and practical) NDA system. Based on MCNP simulations, with the use of a DD neutron generator, a preliminary optimization study was performed and will be shown here.

Journal Articles

Delayed gamma-ray spectroscopy, 1; Phase-I summary, Phase-II preview, and continuous solution monitoring

Rodriguez, D.; Rossi, F.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (Internet), 2 Pages, 2018/11

Safeguards verification of high-radioactivity nuclear material (HRNM) solution samples is performed by HKED analysis for Pu/U element masses and time-consuming destructive analysis for isotopic compositions. To reduce the composition verification time, we have been collaborating with the EC-JRC to develop Delayed Gamma-ray Spectroscopy (DGS), which utilizes fission product $$gamma$$ rays with $$>$$ 3 MeV energy, above the intense passive background. We present the DGS Phase-I development summary and the Phase-II development plan. Additionally, we report about the $$gamma$$ ray pipe monitoring demonstration we performed at TRP and our process monitoring concept that includes GR pipe monitoring and self-interrogation DGS technique in reprocessing facilities.

36 (Records 1-20 displayed on this page)