「物質創成の起源・進化を探り物質階層の普遍性を解明する」
原子核科学研究センターは東京大学大学院理学系研究科附属の施設として、理化学研究所加速器施設との共同事業および欧州原子核研究機構での共同研究を中心として、重イオンビームを用いた原子核物理学や加速器科学と周辺の応用分野を含む重イオン科学研究を推進しています。
東京大学原子核科学研究センター (CNS) では、原子核からクォークに至るハドロン多体系の物理を研究しています。加速器技術の発展に伴い、我々は従来到達し得なかった領域に踏み込む道具をこの手に得ることになりました。CNS と強い研究連携体制にある理化学研究所の RI ビームファクトリー、とりわけ東大CNSの建設した、SHARAQ、CRIBという2つの大型実験装置はその代表であり、さらに低速エキゾティックRIビームを生み出すためのOEDO計画が進行中です。 CNS は 7 人の教員(教授 1, 准教授 3, 講師 1, 助教 2)と大学院生・ポスドクを中心としたメンバーで、これらの巨大加速器施設における最先端研究を推進しています。個々の研究テーマについてはこちらをご覧ください。
研究室
研究者紹介
CNSに所属した研究者
CNS Seminar by Prof. Angela Bonaccorso (Mar13)
Place: Nishina-hall (onsite)
Date: Mar. 13 (Wed) 13:00(-14:30)
Speaker: Prof. Angela Bonaccorso (INFN-Pisa)
Title: Phenomenological and ab-initio optical potentials for nucleon-12C scattering
Abstract: Absolute values of neutron knockout cross sections from exotic projectile depend strongly on the optical potentials used to describe the core-target interaction and the neutron-target final state interaction. The strong dependence on other ingredients of the calculations, such as initial state wave function and method used to calculate the cross section have been also discussed at length in the past. Recently C. Hebborn , T.R. Whitehead, A.E. Lovell and F.M. Nunes PRC108.014601.2023 quantified the dependence on the optical potentials by a Bayesian analysis. On the other hand in a recent publication we studied the imaginary part of the nucleon-12C and nucleus-12C optical potential (I. Moumene and A.B, PRC108, 044609 (2023)) with the aim of finding the potentials that would best describe the reaction cross sections and eventually the stripping part of knockout. Now we concentrate on the real part of the n-12C potential and its effects on the elastic scattering angular distribution and total elastic cross sections. An important point to discuss is the method used to normalize the experimental distributions. This is necessary to then describe the diffractive part of knockout.
OEDO-SHARAQ研究成果のプレスリリース
OEDOとSHARAQを用いた放射性同位体79Seの核変換データの研究成果がPhysics Letters Bに出版され、 プレスリリースを行いました(「長寿命核廃棄物の減容および宇宙での元素の起源の解明へ」)。成果記事について英国の文学部の教授より詩が送られました。
RIKEN RIBF + CNS Seminar by Prof. Yi-Hua Lam (Feb27)
Place: Nishina Hall, RIKEN Wako Campus
Date: Feb. 27 (Tue) 13:30 - 15:00
Speaker: Prof. Yi-Hua Lam (Institute of Modern Physics, Chinese Academy of Sciences)
Title: Sensitivity of the SAX J1808.4−3658 Photospheric Radius Expansion Bursts to Thermonuclear Reaction-Rate Variations
Abstract: More than half of the discovered Type-I X-ray bursters generate photospheric radius expansion (PRE) bursts. Nevertheless, the PRE bursting mechanism is not adequately understood due to the intricate thermo-hydrodynamics, varying accretion rates and non-constant recurrence times throughout a series of consecutive type-I X-ray bursts (XRBs). A set of PRE-burst models matching with observations are highly desired within the community to understand the burst mechanism and evolution of thermo-hydrodynamics, and to unfold the information embedded in X-ray signals, especially the properties of the accreting neutron star of a low-mass X-ray binary, nucleosynthesis, and burst ash composition. To construct these PRE models, identifying and reducing the uncertainties of important thermonuclear reactions are our prime aims. Here we investigate the sensitivity of PRE-burst models for the SAX J1808.4–3658 X-ray source on the uncertainties in (alpha, p), (alpha, gamma), (p, alpha), and (p, gamma) nuclear reaction rates. The fully self-consistent PRE-burst models consider the mutual influence between changes in extreme astrophysical conditions and changes in nuclear energy generation throughout the evolution of the sequential bursts. These PRE-burst models are instantiated from the state-of-the-art one-dimensional multi-zone thermo-hydrodynamic stellar evolution code, KEPLER. The impacts of all relevant reaction rates of proton-rich isotopes up to around mass 80 are individually studied by scaling up and down the respective reaction rate for a factor of 10. We identify and present a number of uncertain reaction rates that significantly influence the reproduction of observables (i.e., burst light curves, fluences, and recurrence times) and the prediction of burst ashes. The PRE-burst model is more sensitive to the change of reaction rates compared to all previous sensitivity studies. Moreover, this is the first XRB sensitivity study based on direct comparison with observations. In this talk, I will present the sensitivity-study results, deepening our understanding of the nuclear processes that shape observables of PRE bursts, and serving as a guidance for future nuclear astrophysics to reduce nuclear uncertainties in PRE models.