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Iain Lee


Postgraduate Research Student

Academic and research departments

Theoretical Nuclear Physics Group.

My research project

My publications

Publications

J J Valiente-Dobon, R H Regan, C Wheldon, C Y Wu, N Yoshinaga, K Higashiyama, J F Smith, D Cline, R S Chakrawarthy, R Chapman, M Cromaz, P Fallon, S J Freeman, A Gorgen, W Gelletly, A Hayes, H Hua, S D Langdown, I Y Lee, X Liang, A O Macchiavelli, C J Pearson, Z Podolyak, G Sletten, R Teng, D Ward, D D Warner, A D Yamamoto (2004)Ba-136 Studied Via Deep-Inelastic Collisions: Identification of the (vh(11/2))(10+)(-2) Isomer, In: Physical Review C69(2)

A multinucleon transfer reaction between a thin self-supporting Pt-198(78) target and an 850 MeV Xe-136(54) beam has been used to populate and study the structure of the N=80 isotone Ba-136(56). Making use of time-correlated gamma-ray spectroscopy, evidence for an I-pi=(10(+)) isomeric state has been found with a measured half-life of 91+/-2 ns. Prompt-delayed correlations have also enabled the tentative, measurement of the near-yrast states which lie above the isomer. Shell-model calculations suggest that the isomer has a structure which can be assigned predominantly as (nuh(11/2))(10+)(-2). The results are discussed in terms of standard and pair-truncated shell-model calculations, and compared to the even-Z N=80 isotones ranging from Sn-130(50) to Er-148(68). A qualitative explanation of the observed dramatic decrease in the B(E2:10(+)-->8(+)) value for the N=80 isotones at Ba-136 is given in terms of the increasing single-hole energy of the h(11/2) neutron configuration as the proton subshell is filled. The angular momentum transfer to the binary fragments in the reaction has also been investigated in terms of the average total gamma-ray fold versus the scattering angle of the recoils.

HN Liu, J Lee, P Doornenbal, H Scheit, S Takeuchi, N Aoi, KA Li, M Matsushita, D Steppenbeck, Handing Wang, H Baba, E Ideguchi, N Kobayashi, Y Kondo, G Lee, S Michimasa, T Motobayashi, A Poves, H Sakurai, M Takechi, Y Togano, Jeffrey Tostevin, Y Utsuno (2017)Intruder configurations in the ground state of 30Ne, In: Physics Letters Section B: Nuclear, Elementary Particle and High-Energy Physics767pp. 58-62 Elsevier

We report on the first detailed study of intruder configurations in the ground state of 30Ne by means of the 12C(30Ne,29Ne+γ)X one-neutron knockout reaction at 228 MeV/nucleon. Using a combined analysis of individual parallel momentum distributions and partial cross sections we find: (a) comparable p- and d-wave removal strength to 29Ne final states with excitation energies below 200 keV, and (b) significant p-wave removal strength to the 620 keV state of 29Ne, and (c) no evidence for f-wave intruder strength leading to bound 29Ne final states. The SDPF-U-MIX shell model calculation in the sd-pf model space provides a better overall agreement with the measured energy levels of 29Ne and the fp-intruder amplitudes in 30Ne than the SDPF-M prediction, suggesting that the refinement of the sd-pf cross shell interaction and extension of the model space to include the 2p1/2 and 1f5/2 levels are important for understanding the island of inversion.

H Liu, J Lee, P Doornenbal, H Scheit, S Takeuchi, N Aoi, K Li, M Matsushita, D Steppenbeck, H Wang, H Baba, E Ideguchi, N Kobayashi, Y Kondo, G Lee, S Michimasa, T Motobayashi, H Sakurai, M Takechi, Y Togano, JA Tostevin, Y Utsuno (2015)Single-Neutron Knockout Reaction from 30Ne, In: JPS Conference Proceedings6pp. 030003-1

Intruder configurations in the ground state of 30Ne were studied using the one neutron knockout reaction 12C(30Ne,29Ne + γ)X at 228 MeV/nucleon at the Radioactive Isotope Beam Factory. Individual parallel momentum distributions and partial cross sections were measured by tagging γ rays. A significant population of the p-wave intruder state in 29Ne is observed, providing further experimental evidence for the vanishing of the N = 20 shell closure.

Iain Lee, Alexis Diaz-Torres (2019)Populating high spin states of a compound nucleus with the incomplete fusion mechanism: the effectiveness of heavy projectiles, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS IOP PUBLISHING LTD

Using a classical dynamical reaction model, angular momentum (____textit{L}) values of a compound nucleus due to incomplete fusion at energies near and above the Coulomb barrier are studied. In this model, a projectile consisting of two cluster nuclei is fired at a stationary target nucleus. After breakup of the projectile due to Coulombic and nuclear forces, an ____(____alpha____)-cluster fuses with a ____textsuperscript{208}Pb target, forming an excited ____textsuperscript{212}Po compound nucleus. Results show that all incomplete fusion reactions produced higher angular momentum in the compound nucleus compared to a direct beam of ____(____alpha____) particles at the same incident energy. The highest angular momentum values produced in ____textsuperscript{212}Po for near and above Coulomb barrier energies were obtained using a ____textsuperscript{20}Ne projectile, at 16____(____hbar____) and 40____(____hbar____) respectively. This produced 25____% and 50____% ____textit{L} values above the next highest-Z projectile used, ____textsuperscript{8}Be, respectively.