集中講義 (2015.12.28-29)：飯田圭氏（高知大）

2015年9月4日 | 新着情報

2日間の集中講義を以下の日程で行います。

題目：「中性子星の物理」

講師：飯田　圭氏（高知大学　教授）

日程：

12月　28日（月）10：30～12：00, 14：00～15：30, 16：00～17：30

12月　29日（火）10：30～12：00, 14：00～15：30, 16：00～17：30

場 所：筑波大学自然学系棟D312

内容：中性子星は超新星爆発のあとに残るコンパクトな天体の一形態である。中性子星で見られる多彩な現象から、地上では作り得ない高密度物質の性質をさぐる。講義内容は主に、以下の通り。

１．中性子星の魅力とパルサーの魔力

２．中性子星物質の多彩な物性

３．中性子星の進化と高密度物質

４．パルサーグリッチ現象と中性子渦糸のピン止め

５．中性子星クラストとパスタ原子核

講義資料（制限あり）PPT1, PPT2, PPT3, PPT4, PPT5

セミナー(2015.9.15)：渡辺元太郎氏 (IBS)

2015年8月18日 | 新着情報

9月13-15日の日程で、Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS)[韓国]から渡辺元太郎氏の訪問があり、筑波大の当研究室に滞在します。また、以下のセミナーを開催する予定です。

Date: September 15th (Tue) 11:00-
Place: Meeting Room A, Center for Computational Sciences (1F)
Lecturer: Dr Gentaro Watanabe (IBS, Korea)
Title: Quantum fluctuation theorems and generalized measurements: towards their verification using cold atomic gases
Abstract: We discuss transient fluctuation theorems in quantum systems, i.e., quantum Jarzynski equality and Tasaki-Crooks relation. In these quantum fluctuation theorems, work is defined by the projective energy measurements at the beginning and the end of the force protocol. However, projective measurements are difficult to implement experimentally. This is a major obstacle to the direct verification of the transient fluctuation theorems in quantum systems. It is thus important to ask whether these projective measurements can be replaced with generalized measurements which could be easier to implement [1-3]. First, we prove a kind of no-go theorem that only projective measurements can satisfy the Crooks relation for an arbitrary force protocol [1]. Then we show that, however, we can overcome this no-go theorem [3]. We will also discuss the future prospects towards the verification of the quantum fluctuation theorems using cold atomic gases.
[1] B. P. Venkatesh, G. Watanabe, and P. Talkner, New J. Phys. 16, 015032(2014).
[2] G. Watanabe, B. P. Venkatesh, P. Talkner, M. Campisi, and P. Haenggi, Phys. Rev. E 89, 032114 (2014).
[3] G. Watanabe, B. P. Venkatesh, and P. Talkner, Phys. Rev. E 89, 052116 (2014).
* The seminar is given in English.

不安定核セミナー開催（2015.9.2)

2015年8月7日 | 新着情報

以下の内容で、第34回つくば不安定核セミナーを開催致します。また、セミナーに先立ち、13:30-15:45まで、同じ会場において講義を行います。また、すべて日本語での講演（スライドは英語）で行います(PDF)。

題目：RIBFにおける不安定核の崩壊測定と重元素合成 (Study of decay properties and synthesis of heavy elements at RIBF)

講師: 西村 俊二

所属: 理化学研究所・仁科加速器研究センター、先任研究員 日時: 2015年9月2 日( 水 )16:00より

場所: 筑波大学、総合研究棟B、1階110講義室

概要：

A new generation radioactive isotope facility (RIBF) has started providing highest intensity neutron-rich nuclei using in-flight fission of a 345 MeV/nucleon 238U beam. Bringing together with high detection efficiency gamma-ray detectors (Euroball HPGe) and newly developed beta-counting system (WAS3ABi), harvest of decay properties for several hundreds of exotic nuclei has been conducted using the EURICA spectrometer [1-5].
My talk will describes the basis and recent progress made in beta-gamma spectroscopy and related topics of the rapid-neutron capture process (r process), sequence of neutron-capture and beta-decay processes. Future projects related to nuclear structure and nuclear astrophysics will be presented to discuss our perspective at RIBF.
[1] S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006 (2012).
[2] H. Watanabe et al., Phys. Rev. Lett. 111, 152501 (2013).
[3] Z.Y. Xu et al., Phys. Rev. Lett. 113, 032505 (2014).
[4] G.S. Simpson et al., Phys. Rev. Lett. 113, 132502 (2014).
[5] G. Lorusso et al., Phys. Rev. Lett. 114, 192501 (2015).

セミナー(2015.7.1)：Dr Anatoli Afanasjev (Mississippi State University)

2015年6月19日 | 新着情報

学振招へい（短期）で滞在されるミシシッピ州立大学の Anatoli Afanasjev氏のセミナーを7月1日午前10:30より自然学系D棟312号室で開催します。

Lecturer: Prof. Anatoli Afanasjev (Mississippi State University)
Title: Addressing theoretical uncertainties in nuclear DFT
Abstract:
Even with new generation of experimental facilities such as RIKEN, FRIB and SU- PERHEAVY FACTORY, almost half of the Z ≤ 120 nuclei will be beyond of experimental reach. However, the modeling of nuclear astrophysical processes requires precise nuclear information on masses, β-decay rates, fission properties etc. In such a situation it is im- portant to understand theoretical uncertainties on global scale and their sources. This will also allow to improve nuclear structure models and to define better fitting protocols. In my talk these questions will be addressed within the framework of covariant density functional theory.
I will start from the global assessment of the description of ground state observables of even-even nuclei in the CDFT framework. Calculated binding energies, the deformations, radii, neutron skins, two-neutron separation energies and the positions of the proton-drip line will be compared in a systematic way with available experimental data. The estimates of theoretical uncertainties in these observables with increasing isospin and their evolution up to two-neutron drip line will be provided. Then I will focus on two-neutron drip line and superheavy nuclei and the sources of theoretical uncertainties in their description.
It is clear that the current generation of energy density functionals has some important limitations. The possibilities of their extension and thus the improvement of the descrip- tion of experimental data and the decrease of theoretical uncertainties will be discussed.

不安定核セミナー開催（2015.6.10)

2015年6月9日 | 新着情報

6月10日に不安定核セミナー＆講義を筑波大学において開催します。

詳細はこのページをご覧ください。

セミナー(2015.6.8)：Dr Panagiota PAPAKONSTANTINOU (IBS, RISP)

2015年6月3日 | 新着情報

韓国のiBSからPapakonstantinou氏が来られて以下のセミナーを行います。場所は自B214です。

Date/Time: June 8 (Mon), 13:45 pm-
Place: B214 (Institute of Natural Sciences, Univ. of Tsukuba)
Lecturer:  Panagiota PAPAKONSTANTINOU (Institute for Basic Science, Rare Isotope Science Project)
Title: Beyond the mean-field picture, with realistic nuclear interactions
Abstract:
In the past decades, energy-density functional methods have advanced greatly the field of nuclear structure. They have allowed a microscopic and unified description of many properties in medium-mass and heavy nuclei, from masses and sizes to giant resonances, as well as nuclear matter. Known issues include the poorly constrained time-odd terms and the concept of non-linear density dependencies. Fitting the free parameters on the mean-field level means, moreover, that double counting of unknown effects is inevitable in beyond-mean-field applications. In this talk I will present an effort to describe nuclear properties, starting from microscopic NN(N) Hamiltonians, which allows for systematic and controlled extensions of mean-field theory, and can thus be applied in heavy nuclei. The Hamiltonians are first softened via unitary transformations. They can describe nuclear ground states within perturbation theory. They are then applied in linear response theory, namely the random phase approximation and its extensions, to study giant resonances and other vibrational modes. This line of work bridges strictly ab initio methods, restricted to very low energies and light nuclei, and more phenomenological, traditional approaches. It exploits nsights from both and could help them advance in tandem.

セミナー(2015.5.22)：Dr Javier Menendez (東大理)

2015年5月15日 | 新着情報

東京大学に学振・外国人特別研究員・Javier Menendez氏のセミナーが5月22日(金) に予定されています。場所・時間等は、セミナーページをご覧ください。

Lecturer: Javier Menendez (Univ. of Tokyo)
Title: From nuclear structure to double-beta decay
Abstract:
First I will cover the main achievements, and point to future work, in nuclear structure shell model calculations of medium-mass nuclei based on nuclear forces predicted by chiral effective field theory. These include very successful description of masses and spectroscopy of oxygen, calcium isotopes as well as ‘sd-shell’ nuclei. Secondly I will discuss neutrinoless double-beta decay, a key process to access neutrino properties given that the nuclear matrix elements of the process are known accurately. I will present state-of-the-art shell-model neutrinoless double-beta decay calculations, and a comparison to other approaches such as based on mean-field, which is essential to improve our understanding of the nuclear matrix elements.

セミナー(2015.5.18)：Drs Rozzi and Pittalis (Istituto Nanoscienze)

2015年5月13日 | 新着情報

イタリアCNRのIstituto Nanoscienzeから、Carlo Andrea Rozzi氏とStefano Pittalis氏が研究室を訪問し、5/18(月) にセミナーをする予定です。場所と時間は通常と異なりますのでご注意ください。

(1)
Title: Ultrafast dynamics in light-harvesting and photovoltaics: a theoretical and experimental investigation
Speaker: Carlo Andrea Rozzi (CNR – Istituto Nanoscienze)
Place: Workshop room, Center for Computational Sciences
Time: May 18, 11:00-12:00
Abstract:
It is known that the primary steps of photoinduced energy and charge transfer occur on extremely fast time scales in many natural and man-made compounds that perform conversion of sunlight into chemical or electrical energy. These processes have traditionally been interpreted in terms of the incoherent kinetics of optical excitations and of charge hopping, but recently signatures of quantum coherence were observed in energy transfer in photosynthetic bacteria and algae [1,2]. We have studied the early steps of photoinduced charge separation in reference systems for artificial photosynthesis and photovoltaics by combining Time-dependent Density Functional Theory simulations of the quantum dynamics and high time resolution femtosecond spectroscopy. Our results show that the coherent coupling between electronic and nuclear degrees of freedom is of key importance for charge delocalization and transfer in both of covalently and non-covalently bonded systems [3,4]. We have exploited the results of our research to design, synthesize and characterize a novel molecular scaffold for photovoltaic applications [5].
[1] Engel, G. S. et al. Nature 446, 782-786 (2007).
[2] Collini, E. et al. Nature 463, 644-647 (2010).
[3] Rozzi, C. A., Falke S. et al., Nat. Comm. 4, 1602 (2013)
[4] Falke S., Rozzi, C. A. et al., Science, 344, 1001 (2014)
[5] Pittalis S., et al., Adv. Func. Mat. (2014)
(2)
Title: A roundtrip journey from spin-entanglement in atoms and molecules
to density functional theory
Speaker: Stefano Pittalis (CNR – Istituto Nanoscienze)
Place: Workshop room, Center for Computational Sciences
Time: 13:30-14:30
Abstract:
I will present an investigation on spin entanglement in many-electron systems within the framework of density functional theory [1]. In particular, I will show that, the entanglement length — which is extracted from the spatial dependence of the local concurrence — is a sensitive indicator of atomic shells, and reveals the character, covalent or metallic, of chemical bonds. These findings shed light on the remarkable success of modern density functionals, which tacitly employ the entanglement length as a variable, and open the way to further research on entanglement-based functionals.
[1] S. Pittalis, F. Troiani, C. A. Rozzi, G. Vignale, Phys. Rev. B 91, 075109 (2015)

ビジター（2015.6.22~8.16）：Dr Anatoli Afanasjev氏（ミシシッピ州立大学）

2015年5月1日 | 新着情報

ミシシッピ州立大学教授 Anatoli Afanasjev氏が6月22日より2ヶ月間、日本学術振興会外国人招へい研究者（短期）として筑波大学原子核理論研究室に滞在される予定です。

新メンバー：鷲山さん、齊藤さん、八百板さん。

2015年4月1日 | 新着情報

我々の研究グループに、理化学研究所から鷲山公平さんが研究員として着任し、新たにメンバーとして加わりました。柏葉さんは修士課程M1に進学。また、物理学類4年生の齊藤さん、八百板さんが新たに研究室配属となりました。