- Количество слайдов: 21
Nuclear Theory at Surrey The Cosener’s House, Abingdon, Wednesday 23 rd May 2007 Jeff Tostevin, Department of Physics Faculty of Engineering and Physical Sciences University of Surrey, UK
People and connectedness
Theory Personnel - May 2007 Academic Staff Jeff Tostevin (Professor) *** Jim Al-Khalili (Professor) *** Makito Oi (Advanced Fellow and Lecturer) Paul Stevenson (Lecturer) Phil Walker (fraction, Professor) Ron Johnson (Emeritus Professor) Research Staff *** Qiang Zhao (Advanced Fellow) Natasha Timofeyuk (PDRA) A. N. Other (PDRA) *** Alex Brown (MSU, Visiting Fellow: 4 months) *** Ian Thompson (LLNL, Visiting Fellow: 2 months) Research students 12 PGR students *** *** ***
Collaboration and training We link strongly with both the UK and international experimental programmes in RIB (GSI, GANIL, TRIUMF, MSU, RIKEN) and hadron physics (MAMI, Beijing, JLab); Joint grants/investigators RISING (GSI) – Tostevin, Stevenson p-decay (L’pool, Daresbury) – Al-Khalili, Stevenson Laser Spectroscopy (B’ham, Manchester) - Stevenson ANU (Break-up and/on Fusion) -Tostevin Experimental proposals, e. g. RIKEN (RIBF) 80 Zn 78 Ni, 2 p knockout MSU (NSCL) 2 N knockout, pickup, break-up Training Schools (theoretical pull to attract Visiting Fellows) Mini-School on the Nuclear Shell Model – March 2007 - Brown Mini-School on Direct Nuclear Reactions (planned) – Thompson based on successful JINA event at MSU
Science base and scope
Activity – increasingly, the borders merge Nuclear reactions/dynamics: (Tostevin, Al-Khalili, Johnson) Reactions for exotic nucleus spectroscopy: e. g. nuclear- and nucleon-induced knockout, transfer, breakup, proton decay… Reaction dynamics and novel few- and many-body methodologies. Reactions for astrophysics and fusion reactions. Emphasis is on prediction of and quantitative confrontation of new data and phenomena. Nuclear structures/dynamics: (Stevenson, Oi, Walker) Few, many-body and collective dynamical models. Unconstrained deformed mean field (and beyond) calculations. Time-dependence, dynamics, the nuclear response, and the GR. 3 D rotation – novel rotational modes, Bose condensates. Isomeric states Hadron physics: (Zhao, Al-Khalili) Hadron resonances and spectroscopy, multi-quark models.
Theoretical activity – Recent “Letters” Nuclear reactions/dynamics: PRL 98, 152701 (2007), 96, 032502 (2006), 96, 162501 (2006), PRL 93, 042501 (2004), 91, 232501 (2003), 91, 012501 (2003), PRL 90, 159201 (2003), Nature 435, 922 (2005) Nuclear dynamics/structures: PLB 641, 34 (2006), 634, 30 (2006), PRL 92, 252501 (2004), PLB 606, 43 (2005), 576, 75 (2003), 545, 291 (2002) Hadron physics: PRL 96, 132003 (2006), 91, 022004 (2003), PLB 645, 173 (2007) PLB 636, 197 (2006), 631, 22 (2005), 596, 317 (2004), PLB 590, 176 (2004), 586, 91 (2004), 553, 211 (2003)
Nuclear Structure Theory
Effective interactions and nuclear responses Giant resonances + fusion reactions + correlations in TDHF nuclear matter + neutron stars effective interaction mean field + beyond isomeric states Ground state structure proton emitting nuclei Funded collaborations with the Surrey/UK experimental effort
Microscopic and Quantal descriptions of structure of many-body systems under rotation • High-spin nuclear structure (Fermion) – Self-consistency in collective and single-particle degrees of freedom – Variational approach with quantum-number projections (and Generator Coordinate Method) VAP (variation after projection) • Rotating Bose-Einstein condensate of ultracold atomic gases in a trap (Boson) – Quantum phase transition from collective modes to vortices and/or the Lowest Landau Level.
Influence of nuclear shapes on decay rates These effects are being investigated in collaboration with Professor F Xu (Beijing University) using a Woods-Saxon. Strutinsky method with a realistic treatment of pairing. J=7 isomer ground state deformation P. M. Walker and F. R. Xu, Phys. Lett. B 635 (2006) 286 F. R. Xu et al. , Phys. Rev. Lett. 92 (2004) 252501 Cut through the calculated energy surface for 256 Fm, versus quadrupole deformation Will high-spin isomers enable the observable stability limits to be further extended?
Nucleon and resonance decays (Halos and astrophysics)
Proton decay and 3 -body decay widths [accuracy of R-matrix methods (Barker), also relevant to knockout reactions to unbound states, e. g. 6 He(2+) ] Intermediate Initial Final 2+ Q 2 n 6 He E 3/2 U Q 1 n 5 He 4 He T h Three-body decay as two sequential decays r 0+
Nuclear reactions for astrophysics Improvements to theories of nucleon transfer and capture reactions - used to determine relevant reaction rates. Mirror symmetry as tool to pin down cross sections for (N, ), (N, ) reactions in stars. (Timofeyuk, Io. P Conf 2007) Possible pre-asymptotic abnormalities in singleparticle behaviour near the drip-line and their influence on (N, ) reaction rates. 1) 7 Li+8 Li (TRIUMF) will test transfer theory and constrain 7 Be(p, )8 B using mirror symmetry solar neutrino physics 2) Pre-asymptotic abnormalities in 9 C and 16 C uncertainties in 8 B(p, )9 C (explosive hydrogen burning) and 15 C(n, )16 C (neutrino-driven wind r-process of supernova explosions)
New reaction methodologies for the most rare, exotic systems
Knockout spectroscopy : First study of 36 Mg 1) Insufficient yield for, e. g. secondary beam inelastic scattering 2) Parent for beta decay, 37 Na, is particle unbound 3) So, use 2 p removal from n-rich (sd-shell) parent, 38 Si 9 Be 1 2 c Microscopic theory of 2 N removal developed at Surrey Phys Rev C 74 064604 (2006) Phys Rev C 70 064602 (2004) Experimental/theory advances: Phys Rev Lett 91 012501 (2003) NATURE 425, 570 (2003), NATURE 435, 924 (2005), NATURE 435, 897 (2005)
The Island of Inversion extends to 38 Si + p n Measured cross sections and those calculated assuming population of the 0 hw components of the final states by the direct 2 p knockout reaction mechanism p n 36 Mg? Monte-Carlo shell model calculations: SDPF-M interaction of Otsuka et al.
RISING: neutron rich systems near 208 Pb Cross section (mb) Work in progress is looking at multi-proton knockout from 208 Pb – and the yields/isomeric ratios of low seniority, high spin isomeric states in heavy neutron-rich systems (Steer, Podolyak, Regan) 208 Pb + Be 1 Ge. V/nucleon number of removed protons Data: T. Kurtukian Nieto, Ph. D Thesis, Universidade de Santiago de Compostela (2007) impact parameter (fm)
Science and connectedness
Collaboration, fundamental questions, training We link strongly with both the UK and international experimental programmes in RIB (GSI, GANIL, TRIUMF, MSU, RIKEN) and hadron physics (MAMI, Beijing, JLab); Joint grants/investigators RISING (GSI) – Tostevin, Stevenson p-decay (L’pool, Daresbury) – Al-Khalili, Stevenson Laser Spectroscopy (B’ham, Manchester) - Stevenson ANU (Break-up and/on Fusion) -Tostevin Experimental proposals: prediction and interpretation e. g. RIKEN (RIBF) 80 Zn 78 Ni, 2 p knockout MSU (NSCL) 2 N knockout, pickup, break-up, etc Training Schools: We have the ‘pull’ to attract first class theorists that enrich and stimulate our programme Fundamental theory developments: Structure, reactions, fewand many-body nuclear (and hadronic) systems.