阿部さん、杉浦さん、修士取得。土田さん、学士取得(Abe-san and Sugiura-san got Msc degree, and Tsuchida-san got Bsc)

Mrs. Abe and Sugiura have been awarded degrees of the Master of Science. Mr Tsuchida has been awarded the Bachelor degree on March 25th, 2021.


Paper by Hinohara and Nakatsukasa was selected as Editors’ Suggestion 日野原さん、中務さんの論文がEditors’ suggestionに

A paper by N. Hinohara and T. Nakatsukasa collaborating with K. Washiyama (Kyushu Univ.) has been published in Physical Review C of American Physical Society, and selected as an Editors’ Suggestion. The paper proposes a new computational method for the collective inertial masses in spontaneous fission dynamics.

日野原さん・中務さんが九州大学の鷲山さんとの共同研究として提案した、自発核分裂における集団慣性質量の新しい計算手法に関する論文が、アメリカ物理学会のPhysical Review Cに出版され、Editors’ Suggestionに選ばれました。

集中講義 (Lectures) 2021.1.13-15:日高義将氏、HIDAKA, Yoshimasa(KEK)

A series of lectures will be delivered by Dr Hidaka (KEK) on “QCD matter at Extreme Conditions”, at Meeting Room A, CCS, University of Tsukuba, in January 13-15, 2021. The lecture is given in Japanese.

日程:2021年1月13日 10:30-16:45、1月14日 10:30-16:45、1月15日 13:30-16:45
場所:筑波大学計算科学研究センター 会議室A
内容: 宇宙初期や高密度天体の内部などに現れる超高温,超高密度,超磁場中といった極限状態におけるハドロン(QCD)の物性について講義する.このような極限状態のQCDの性質を理解するための解析手法について基本的な事柄を紹介し,それがどのようにQCDへ応用され,どのような理解に至っているか解説する.また,最近の物性物理で発展しているトポロジーを用いた量子相のアプローチのQCDへの応用についても紹介する.

セミナー(Seminar) 2020.12.11: Dr Cheng-Jun Xia (Zhejiang University, China)

Lecturer: Cheng-Jun Xia (Zhejiang University)
Date/Time: 15:30, December 11 (Fri), 2020
Place: Meeting Room A in Center for Computational Sciences, together with Zoom.
Title: Nuclear pasta structures and symmetry energy
Abstract: In the framework of the relativistic mean field model with Thomas-Fermi approximation, we study the structures of low density nuclear matter in a three-dimensional geometry with reflection symmetry. The numerical accuracy and efficiency are improved by expanding the mean fields according to fast cosine transformation and considering only one octant of the unit cell. The effect of finite cell size is treated carefully by searching for the optimum cell size. Typical pasta structures (droplet, rod, slab, tube, and bubble) arranged in various crystalline configurations are obtained for both fixed proton fractions and β-equilibration. It is found that the properties of droplets/bubbles are similar in body-centered cubic (BCC) and face-centered cubic (FCC) lattices, where the FCC lattice generally becomes more stable than BCC lattice as density increases. For the rod/tube phases, the honeycomb lattice is always more stable than the simple one. By introducing an ω-ρ cross coupling term, we further examine the pasta structures with a smaller slope of symmetry energy L = 41.34 MeV, which predicts larger onset densities for core-crust transition and non-spherical nuclei. Such a variation due to the reduction of L is expected to have impacts on various properties in neutron stars, supernova dynamics, and binary neutron star mergers.

This seminar is given in English. Contact the organizer (Kai Wen) to obtain the Zoom link.

セミナー(Seminar) 2020.11.20: Dr Simin Wang (MSU, USA)

Lecturer: Simin WANG (MSU)
Date/Time: 14:00, November 20 (Fri), 2020
Place: Meeting Room A in Center for Computational Sciences, together with Zoom.
Title: Study of the two-proton radioactivity
Abstract: Two-proton (2p) radioactivity is a rare decay mode found in a few very proton-rich isotopes. The 2p decay width and properties of emitted protons carry invaluable information on nuclear structure in the presence of a low-lying proton continuum. For example, in mid-heavy nuclei, the measured 2p decay of 67Kr turned out to be unexpectedly fast [1]. And more recently, as the mirror of the halo nucleus 11Li, 11O was observed for the first time with a very broad peak [2]. To understand these exotic phenomena, we apply the Gamow coupled-channel method, which describes structure and decays of three-body systems within one coherent theoretical framework by utilizing resonant and scattering states in eigenfunction expansion [3]. The calculated lifetimes, angular correlations, and other properties indicate that the nuclear inner structure and continuum effect play a significant role in the decay process [2,3]. Moreover, to provide insights into the impact of nucleonic superfluidity on two-nucleon decay processes, we are developing a novel time-dependent approach, which will allow us to consider different experimental initial-setups and directly compare the predictions and data without losing structural information. With this new approach, we reveal the different dynamics of 2p and 2n decays.
[1] Goigoux et al., Phys. Rev. Lett. 117, 162501 (2016).
[2] T.B. Webb et al., Phys. Rev. Lett. 122, 122501 (2019).
[3] S. M. Wang and W. Nazarewicz, Phys. Rev. Lett. 120, 212502 (2018).

This seminar is given in English. Contact the organizer (Kai Wen) to obtain the Zoom link.

Young Faculty Award in University of Tsukuba (Dr Shunsuke Sato); 筑波大学若手教員奨励賞受賞(佐藤駿丞)

Dr Shunsuke Sato, International Tenure-Track Assistant Professor, has been awarded Young Faculty Award in University of Tsukuba, for his outstanding contributions to increasing research activities.


セミナー(Seminar) 2020.10.23: Dr Toshimi Suda (Tohoku Univ.)

Lecturer: Toshimi SUDA (Tohoku University) [東北大学 電子光理学研究センター 須田利美]
Date/Time: 14:00, October 23 (Fri), 2020
Place: Meeting Room A in Center for Computational Sciences, together with Zoom
Title: Electron scattering for structure studies of proton and exotic nuclei
Abstract: 本セミナーでは、東北大学と理化学研究所の電子加速器を利用して進めている電子散乱による陽子と短寿命不安定核の構造研究について紹介します。
1)陽子電荷半径 : ULQ2 (Ultra Low Q2)@東北大電子光理学研究センター
史上最低エネルギー(Ee = 20 – 60 MeV)の電子・陽子弾性散乱から、最も信頼度の高い陽子電荷半径を決定します。ここ数年、科研費により電子光理学研究センター内に新しくビームラインと2連の散乱電子スペクトロメータを建設しています。本研究は、「陽子半径パズル」と呼ばれる陽子電荷半径に関する混乱に決着をつけ、正しい陽子電荷半径の決定が目標です [1,2]。セミナーでは、陽子半径パズル、ULQ2 計画そしてコミッショニングの現状と今後の展望を紹介します。
2)短寿命不安定核の電荷密度分布 : SCRIT@理化学研究所 RIBF
 私たちは、前例のない電子散乱による短寿命不安定核研究を可能にするSCRIT電子散乱施設を理化学研究所 RIビームファクトリーに建設し稼働を開始させました [3]。SCRIT 施設の現場と今後の研究展望について紹介します。
 電子弾性散乱で決定される電荷密度分布は主として陽子分布の情報を与えますが、電荷密度分布の4次モーメントから核内中性子分布の平均二乗半径が決定できる可能性が理論的に指摘されました [4,5]。この指摘を受けて、原子核構造研究に最適な電子散乱で不安定核の陽子と中性子分布を同時決定する可能性の検討を進めています。セミナーではこの可能性についても皆さんと議論したいと考えています。
1. “Measurement of proton charge radius by low-energy electron scattering.”, T. Suda et al., J. Part. Acc. Soc. Japan 15 (2018) 52-59.
2. 「極運動量移行領域での電子・陽子弾性散乱による陽子電荷半径の精密決定.」須田利美、塚田暁、 原子核研究 61 (2017) 87.
3. “Prospects for electron scattering on unstable exotic nuclei.”, T. Suda and H. Simon, Prog. Part. Nucl. Phys. 96 (2017) 1.
4. “The n-th order moment of the nuclear charge density and contribution from neutron”, H. Kurasawa and T. Suzuki, Prog. Theor. Exp. Phys. 11 (2019) 113D01
5. “The mean square radius of the neutron distribution and the skin thickness derived from electron scattering.”, H. Kurasawa, T. Suda and T. Suzuki, arXiv 2009.00759

This seminar is given in Japanese.

新メンバー:尾﨑さん、小澤さん、土田さん New members: Ozaki, Ozawa, and Tsuchida

New graduate students in the Master course, Ozaki and Ozawa, and a new undergraduate student, Tsuchida, have joined our group.


International external review (2020.2.19-21)

The external review of Center for  Computational Sciences (CCS) will take place in February 19-21, 2020. Our staff members are associated with both Division of Nuclear Physics  (T. Nakatsukasa [Division Head], Y. Hashimoto, N. Hinohara) and Division of Quantum Condensed Matter Physics (K. Yabana [Division Head], S. Sato).


セミナー(Seminar) 2019.12.13: Dr Shuichiro Ebata (Saitama)

We have a seminar as follows:

Lecturer: Shuichiro EBATA (Saitama University)

Date: December 13 (Fri), 2019

Place: Meeting Room B in Center for Computational Sciences

Tittle: Mean-field studies for nuclear fission and fusion

Abstract: Nuclear fission and fusion are fundamental phenomena in nuclear physics, and so far, many studies have been actively carried out. With the developments of effective interaction and computational resources, it has become realistic to approach theses phenomena by the theoretical calculations. We have developed the method based on mean-field theories to describe fission and fusion. In this presentation, we will show the charge polarization of fission products deduced by the constraint Skyrme Hartree-Fock+BCS model represented in the three-dimensional Cartesian coordinates. And the procedure to describe the superheavy element synthesis using the canonical-basis time-dependent Hartree-Fock-Bogoliubov theory is introduced.