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for the 19.40-MeV state in 
Be for studying the 
Be(
,
)Li
reaction relevant to the cosmological lithium problem岩佐 直仁*; 西尾 勝久; 廣瀬 健太郎; 牧井 宏之; Orlandi, R.; 洲嵜 ふみ; Smallcombe, J.; 他7名*
Physical Review C, 112(3), p.035801_1 - 035801_6, 2025/09
The Li(
He,
)Be(
)Li reaction was measured at 
(He) = 28 MeV for studying the Be(,)Li reaction, which is a Be destruction reaction in the big bang nucleosynthesis. Resonant states at 18.9
20.1 MeV in Be were populated by the Li(He,)Be reaction and decay protons to the ground (
) and first-excited states () in Li were well separated and measured. The resonance width 
and branching ratio / for the 19.40-MeV state in Be were deduced to be 342
112 keV and 11.2 3.5 5.0 (syst.)%, respectively. The 
Be(,)Li reaction cross section was deduced.
Sn using the GRIFFIN spectrometer at TRIUMFSyeda, N. K.*; Smallcombe, J.; 他44名*
Nuclear Physics A, 1059, p.123090_1 - 123090_5, 2025/07
The semi-magic 
Sn isotopes display signs of shape coexistence in their excited 0
states, which, in contrast to the spherical 0 ground states, are deformed. This paper investigates the nuclear structure of Sn using the competing 
decay and electron capture of a radioactive beam of Sb produced at the TRIUMF-ISAC facility using the GRIFFIN spectrometer. This study will allow for an in-depth understanding of the excited 0 states in Sn, by focusing on their decay patterns. In the present experiment, transitions at 856.2-keV and 1405.0-keV, which were observed in an earlier decay study but not placed in the Sn level scheme, have been assigned to the level scheme in connection to the 0 3 level at 2156.0-keV. Properly assigning these transitions refines the level scheme and enhances our understanding of the nuclear structure in Sn.
HfAlayed, B.*; Page, R. D.*; Joss, D. T.*; Uusitalo, J.*; Qi, C.*; Briscoe, A. D.*; AlAqeel, M. A. M.*; Andel, B.*; Antalic, S.*; Auranen, K.*; et al.
Physical Review C, 110(3), p.034303_1 - 034303_9, 2024/09
Excited states in the neutron-deficient nuclide Hf have been investigated in experiments performed at the Accelerator Laboratory of the University of Jyvaskyla.
Se from combined conversion-electron and 
-ray spectroscopySmallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Muir, D.*; Pr
chniak, L.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; et al.
Physical Review C, 110(2), p.024318_1 - 024318_16, 2024/08
被引用回数：1 パーセンタイル：32.65(Physics, Nuclear)In the selenium isotopes various shape phenomena are present, in particular the emergence of a dominant oblate deformation in the most neutron-deficient isotopes has been observed. The scenario of shape coexisting oblate and prolate bands has been proposed across the isotopic chain, with the crossing point of such bands being located near Se, where no coexistence has yet been identified. To determine the presence or absence of any low-lying 
state in Se, confirm the level structure, and interpret the nuclear deformation with theoretical models. A combined internal conversion electron and -ray spectroscopy study was undertaken with the SPICE and TIGRESS spectrometers at the TRIUMF-ISAC-II facility. Nuclear models were provided by the Generalised Triaxial Rotor Model (GTRM) and the collective Generalised Bohr Hamiltonian (GBH). Despite a comprehensive search, no evidence was found for the existence of a state below 2 MeV in Se. Significant discrepancies to the previously established positive parity level scheme were found. GBH calculations using UNEDF1 mass parameters were found to reproduce the revised low-lying level structure well. Se does not have a well defined axial shape. The 2
state at 1601 keV resembles a quasi- excitation rather than a member of a shape coexisting band; the presence of such a band is all but ruled out.
Martel, I.*; Acosta, L.*; Aguado, J. L.*; Smallcombe, J.; 他68名*
Nuclear Instruments and Methods in Physics Research B, 541, p.176 - 179, 2023/08
被引用回数：4 パーセンタイル：59.67(Instruments & Instrumentation)The ISOLDE Scientific Infrastructure at CERN offers a unique range of post-accelerated radioactive beams. The scientific program can be improved with the Isolde Superconducting Recoil Separator (ISRS), an innovative spectrometer able to deliver unprecedented (A, Z) resolution. In this paper we present an overview of the physics and ongoing technical developments.
Eu; Quasiparticle configurations of excited states and structure of 
= 4 bandheads in GdYates, D.*; Kr
cken, R.*; Dillmann, I.*; Garrett, P. E.*; Smallcombe, J.; 他44名*
Physical Review C, 107(6), p.064309_1 - 064309_20, 2023/06
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the 
-process path and following freeze-out region impact the resulting -process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei.
Sun, L. J.*; Fry, C.*; Davids, B.*; Esker, N.*; Wrede, C.*; Smallcombe, J.; 他27名*
Physics Letters B, 839, p.137801_1 - 137801_8, 2023/04
被引用回数：2 パーセンタイル：34.66(Astronomy & Astrophysics)Motivated primarily by the large uncertainties in the thermonuclear rate of the 30PS reaction that limit our understanding of classical novae, we carried out lifetime measurements of 
S excited states using the Doppler Shift Lifetimes (DSL2) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility.
0 transition strength for 
Se using the SPICE spectrometerSmallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.
Physical Review C, 106(1), p.014312_1 - 014312_9, 2022/07
被引用回数：5 パーセンタイル：54.12(Physics, Nuclear)The selenium isotopes lie at the heart of a tumultuous region of the nuclear chart where shape coexistence effects grapple with neutron-proton pairing correlations, triaxiality, and the impending proton dripline. In this work a study of Se by internal conversion electron and -ray spectroscopy was undertaken with the SPICE and TIGRESS arrays. New measurements of the branching ratio and lifetime of the 
state were performed yielding a determination of 
milliunits. Two state mixing calculations were performed that highlighted the importance of interpretation of such 
strength values in the context of shape-coexistence.
decay of 
Te with a novel recoil-decay scintillation detectorXiao, Y.*; Go, S.*; Grzywacz, R.*; Orlandi, R.; Andreyev, A. N.; 浅井 雅人; Bentley, M. A.*; de Angelis, G.*; Gross, C. J.*; Hausladen, P.*; et al.
Physical Review C, 100(3), p.034315_1 - 034315_8, 2019/09
被引用回数：19 パーセンタイル：81.55(Physics, Nuclear)A search for super-allowed decay of N=Z nuclei Te and 
Xe was carried out using a novel recoil-decay scintillator detector at the tandem accelerator facility at Japan Atomic Energy Agency. Inorganic crystal scintillation material of YAP:Ce (Yttrium Aluminium Perovskite) coupled to position-sensitive photo-multiplier tube (PSPMT) was implemented for the first time in a radioactive decay experiment. Residues from the fusion-evaporation reaction 
Ni+
Fe
Xe
were separated by the JAEA Recoil Mass Separator (RMS) and implanted into the YAP:Ce crystal. decays of neutron-deficient tellurium isotopes were identified and proton-emission of 
I was observed. No conclusive evidence was found for the decay chain XeTe 
Sn within 3 days experiment. The cross section limit of 130 pb was obtained for production of two events of Xe, about an order of magnitude below the expectation based on earlier cross section measurements and HIVAP calculations.
廣瀬 健太郎; 西尾 勝久; 田中 翔也*; L
guillon, R.*; 牧井 宏之; 西中 一朗*; Orlandi, R.; 塚田 和明; Smallcombe, J.*; Vermeulen, M. J.; et al.
Physical Review Letters, 119(22), p.222501_1 - 222501_6, 2017/12
被引用回数：60 パーセンタイル：91.03(Physics, Multidisciplinary)JAEAタンデム加速器施設で行った
O+
U反応における多核子移行チャンネルを用いた実験により、
U, 
Np、および
Puの核分裂質量分布を励起エネルギー10
60MeVにおいて測定した。これらのうち、
U, 
Npのデータは本実験により初めて観測された。原子核の殻効果の減衰によって対称分裂すると予想されていた高励起エネルギーにおいても、質量分布が非対称を示すことがわかった。搖動散逸定理に基づく動力学モデル計算との比較から、この振る舞いはマルチチャンス核分裂によるものであることを明らかにした。
西尾 勝久; 廣瀬 健太郎; Lguillon, R.*; 牧井 宏之; Orlandi, R.; 塚田 和明; Smallcombe, J.*; 千葉 敏*; 有友 嘉浩*; 田中 翔也*; et al.
Proceedings of 6th International Conference on Fission and Properties of Neutron-rich Nuclei (ICFN-6), p.590 - 597, 2017/11
We are promoting a fission study using multi-nucleon transfer reactions, where excited states in neutron-rich actinide nuclei, which cannot be accessed by particle capture and/or fusion reactions, are populated. This allows us to study fission in the new region of chart of nuclei. Also, the excited states in the fissioning nucleus are widely populated in the reactions, thus the effects of excitation energy on fission can be investigated. Experiments were carried out at the JAEA tandem facility in Tokai, Japan. We studied reactions using the O beam (9MeV/u) and several actinide target nuclei such as 
Th, U, 
Np, 
Cm. Ejectile nuclei and thus the transfer channels were identified by a newly developed silicon 
E-E detectors. The produced nuclei in one experiment reached more than fifteen. Fission fragment mass distributions (FFMDs) were measured for each isotopes. Measured FFMDs are reproduced by a calculation based on the fluctuation-dissipation model (Langevin-type calculation), where effects of multi-chance fission were included. We also started to measure the prompt neutrons accompanied by fission.
西尾 勝久; 廣瀬 健太郎; Lguillon, R.*; 牧井 宏之; Orlandi, R.; 塚田 和明; Smallcombe, J.*; 千葉 敏*; 有友 嘉浩*; 田中 翔也*; et al.
EPJ Web of Conferences, 146, p.04009_1 - 04009_6, 2017/09
被引用回数：3 パーセンタイル：82.51(Nuclear Science & Technology)The objective of this work is to extend fission data for actinide nuclei not investigated so far in order to understand the fission mechanism, especially for neutron-rich nuclei. Multi-nucleon transfer reactions were used to populate the compound nuclei which cannot be accessed by particle capture or fusion reactions. The experiment was carried out at the tandem facility of Japan Atomic Energy Agency. In the multi-nucleon transfer reactions using O beam, a wide variety of nuclei around a target nucleus was produced. By identifying transfer channels, fission data of nuclei more than fifteen compound nuclei were generated in one experiment. Another feature of transfer reaction is that the excitation energies of a compound nucleus can be populated continuously from the ground state up to several tens MeV, allowing us to study the excitation energy dependence of fission properties. From the excitation function of fission probabilities, fission-barrier heights of neutron-rich actinide nuclei were obtained. Experiments were carried out in the reactions of O + U, Th, Cm, Np. The obtained fission fragment mass distributions were reproduced by a model calculation based on a fluctuation dissipation model.
O + Th reactionLguillon, R.; 西尾 勝久; 廣瀬 健太郎; 牧井 宏之; 西中 一朗*; Orlandi, R.; 塚田 和明; Smallcombe, J.*; 千葉 敏*; 有友 嘉浩*; et al.
Physics Letters B, 761, p.125 - 130, 2016/10
被引用回数：46 パーセンタイル：92.31(Astronomy & Astrophysics)It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the O + Th reaction are used to study fission of fourteen nuclei 
Th, 
Pa, and 
U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 
Th and 
Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model.
Smallcombe, J.
no journal, ,
Recent developments in nuclear physics have elucidated exotic nuclear structure such as new magic numbers and exotic clustering. Even near stable nuclei, state-of-the-art theories provide new interpretations for well-known nuclear-structure problems like the nature of the side bands. To establish such an interesting scenario, direct reactions play a crucial role as a unique tool to access the characteristics of those states. The importance of direct reactions is becoming more evident in the study of exotic nuclei, which can only be accessed by few available methods. Hence it is a good time for specialists in nuclear structure and nuclear reactions to get together and to consider future collaboration schemes.
西尾 勝久; 岩本 修; 牧井 宏之; 廣瀬 健太郎; Orlandi, R.; 洲嵜 ふみ; 塚田 和明; 浅井 雅人; Smallcombe, J.
no journal, ,
長寿命マイナーアクチノイド(MA)原子核を核変換する加速器駆動炉など次世代の原子炉システムを設計するためには高エネルギーまでの中性子入射断面積が必要である。本発表では、実験データがほとんどない非弾性散乱断面積に加え、核分裂断面積、捕獲断面積、(n,2n)断面積を同時に測定する技術開発の計画を示す。
線の測定西尾 勝久; 牧井 宏之; 廣瀬 健太郎; 西中 一朗; Orlandi, R.; Smallcombe, J.; 大槻 勤*; 関本 俊*; 高宮 幸一*
no journal, ,
福島第一原子力発電所の廃止措置において燃料デブリを取り出す際、臨界監視を行って安全を確保する必要がある。これは、体系内での核分裂事象の頻度を検出することで決定するが、環境からの強いバックグランド線下で事象を検出する必要がある。ここでは、核分裂に伴って放出される高エネルギーの即発線(6MeV以上)を測定する方法を提案する。本研究は、このための基礎データとなる
U(n
,f)の線スペクトルを高エネルギー領域まで測定することを目的とする。発表では、開発した線検出器のテスト実験について報告する。
廣瀬 健太郎; 西尾 勝久; Lguillon, R.; 牧井 宏之; 西中 一朗; Orlandi, R.; Smallcombe, J.; 石井 哲朗; 塚田 和明; 浅井 雅人; et al.
no journal, ,
We have developed a measurement system for the multi-nucleon transfer reaction and been studying fission of short-lived minor actinides and neutron-rich nuclides. The experiment was performed at the tandem accelerator facility of Japan Atomic Energy Agency where targets of U, Th, Cm were irradiated with O beams. In this experiment, more than ten nuclides were excited up to few tens of MeV at a time. Projectile-like scattered particles after the multi-nucleon transfer reaction were detected and identified using a E-E silicon telescope. The mass distribution was deduced from the time difference between two fission fragments from the compound nucleus which were detected using two pairs of multi-wire proportional counters. Neutrons accompanied by fission were also measured using liquid scintillators placed around the reaction chamber. In the nucleon transfer reaction, the axis of the angular-momentum transfer can be determined from the direction of the scattered particle. This is one of the most different point from the neutron/ion-induced fusion-fission reaction where only the plane on which the axis lies can be determined. The fission angular distributions with respect to this axis as well as the mass yield, the prompt neutron multiplicity and so on will be presented.
洲嵜 ふみ; 西尾 勝久; 牧井 宏之; 廣瀬 健太郎; Orlandi, R.; Smallcombe, J.
no journal, ,
Multinucleon transfer (MNT) reaction has attracted attention in the fields of nucleosynthesis and the production of superheavy elements because they can produce nuclei with a large neutron number. To produce desired nuclei efficiently and investigate their nuclear properties, it is necessary to determine the optimal beam and target combination and reaction energy, as well as detection angle. The objective of this study is to measure ER cross sections by changing various experimental conditions in order to establish a reliable theoretical model. We have started a program to study MNT reaction using the JAEA Recoil Mass Separator (JAEA-RMS). In contrast to kinematic separators dedicated for fusion reaction, the RMS is advantageous as it can rotate around the target chamber, essential for the study of MNT reactions. As a first attempt, we performed the experiment in the reaction of 
Si + 
Bi. The production rate as a function of recoil angle, recoil energy (thus excitation energy), and incident beam-energy dependence were studied. The alpha-decay of the implanted ERs in the focal plane Si detector was observed online. The result is the first to realize the decay measurement in correlated with ERs, produce in the MNT reaction at a finite angle.
82 nuclei at the JAEA Tandem FacilitySmallcombe, J.; 西尾 勝久; 廣瀬 健太郎; 西中 一朗; 牧井 宏之; Orlandi, R.; 田村 信行*; 後藤 真一*; 大槻 勤*; Andreyev, A.*; et al.
no journal, ,
Recent -delayed fission studies of proton rich 
Hg showed the fission to be dominated by asymmetric fragment masses, in contrast to initial predictions. Models of the potential-energy surface for the path toward scission showed a lower fission barrier for an asymmetrically deformed Hg volume. As a probe of this theoretical interpretation, fission of Hg was induced through the symmetric reaction 
Z
Z. Mass and energy distributions of fragments for a series of bombarding energies were recorded using 2 MWPCs. As a continuation of Z 
fission studies, fission induced in the Li
W reactions were measured. Near A190 a new region of asymmetric fission is predicted to emerge as one moves towards neutron rich nuclei. In preliminary investigations mass asymmetry was observed in fragments of the Li
W reaction. However, fragment kinematics were inconsistent with fission of 
Ir formed by fusion. A follow up experiment was conducted in an attempt to confirm the first observation of fission induced by the Li breakup-fusion reaction 
W
Li,
He
Re. Experimental details and initial results will be presented.
洲嵜 ふみ; 西尾 勝久; 牧井 宏之; 廣瀬 健太郎; Orlandi, R.; Smallcombe, J.
no journal, ,
多核子移行反応は、中性子過剰核を生成する反応として宇宙での元素合成や超重元素合成の分野で注目されている。標的核と入射核が多核子移行反応を通して励起状態の複合核を形成し、これが核分裂をすることなく脱励起すれば蒸発残留核ができる。この生き残り確率は、複合核のスピン分布に依存するが、スピン分布を実験的に決定した例はない。蒸発残留核としての生成核種に基底状態と異なるスピン状態のアイソマーが存在する場合、これらの割合は、複合核スピン分布を知る手がかりとなる。本研究では、JAEA反跳生成核分離装置(JAEA-RMS)を用いて、蒸発残留核を分離し、焦点に設けたシリコン検出器で崩壊を観測することで、生成核種を同定するとともに基底またはアイソマー状態の生成割合を決定した。特に、JAEA-RMSを0度から40度の範囲で回転できること、また電磁場設定で反応のQ値を特定しながら測定できる特徴を活かし、アイソマー比の変化を詳細に調べた。BiにSiを照射し、3核種についてアイソマー比
At(J
=9-)/At(1-), 
Fr(J=8-)/Fr(1-), 
Po(J=25/2+)/Po(9/2+))を獲得したので報告する。
