|
|
Double Chooz collaboration(Abe, Y. et al), & Novella, P. (2016). Muon capture on light isotopes measured with the Double Chooz detector. Phys. Rev. C, 93(5), 054608–18pp.
Abstract: Using the Double Chooz detector, designed to measure the neutrino mixing angle theta(13), the products of mu(-) capture on C-12, C-13, N-14, and O-16 have been measured. Over a period of 489.5 days, 2.3 x 10(6) stopping cosmic mu(-) have been collected, of which 1.8 x 10(5) captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent beta decays, and, in some cases, beta-delayed neutrons. The most precise measurement of the rate of C-12(mu(-), nu)B-12 to date is reported: 6.57(-0.21)(+0.11) x 10(3) s(-1), or (17.35(-0.59)(+0.35))% of nuclear captures. By tagging excited states emitting gamma s, the ground state transition rate to B-12 has been determined to be 5.68(-0.23)(+0.14) x 10(3) s(-1). The heretofore unobserved reactions C-12(mu(-), nu alpha)Li-8, C-13(mu(-), nu n alpha)Li-8, and C-13(mu(-), nu n)B-12 are measured. Further, a population of beta n decays following stopping muons is identified with 5.5 sigma significance. Statistics limit our ability to identify these decays definitively. Assuming negligible production of He-8, the reaction C-13(mu(-), nu alpha)Li-9 is found to be present at the 2.7 sigma level. Limits are set on a variety of other processes.
|
|
|
|
Goldkuhle, A. et al, & Perez-Vidal, R. M. (2020). Lifetime measurements of excited states in neutron-rich Ti-53: Benchmarking effective shell-model interactions. Phys. Rev. C, 102(5), 054334–10pp.
Abstract: Level lifetimes of the yrast (5/2(-)) to 13/2(-) states in the neutron-rich nucleus Ti-53, produced in a multinucleon-transfer reaction, have been measured for the first time. The recoil distance Doppler-shift method was employed and lifetimes of the excited states were extracted by a lineshape analysis aided by GEANT4-based Monte-Carlo simulations. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility in Caen, France, by using the Advanced Gamma Tracking Array for the gamma-ray detection coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification and the Cologne plunger for deep-inelastic reactions. Reduced transition probabilities, deduced from the lifetimes, give new information on the nuclear structure of Ti-53, and are used to benchmark different shell-model calculations using established interactions in the f p shell.
|
|
|
|
Brunet, M. et al, & Nacher, E. (2021). Competition between allowed and first-forbidden beta decays of At-208 and expansion of the Po-208 level scheme. Phys. Rev. C, 103(5), 054327–13pp.
Abstract: The structure of Po-208 populated through the EC/beta(+) decay of At-208 is investigated using gamma-ray spectroscopy at the ISOLDE Decay Station. The presented level scheme contains 27 new excited states and 43 new transitions, as well as a further 50 previously observed. rays which have been (re)assigned a position. The level scheme is compared to shell model calculations. Through this analysis approximately half of the beta-decay strength of At-208 is found to proceed via allowed decay and half via first-forbidden decay. The first-forbidden transitions predominantly populate core excited states at high excitation energies, which is qualitatively understood using shell model considerations. This mass region provides an excellent testing ground for the competition between allowed and first-forbidden beta-decay calculations, important for the detailed understanding of the nucleosynthesis of heavy elements.
|
|
|
|
Briz, J. A., Nacher, E., Borge, M. J. G., Algora, A., Rubio, B., Dessagne, P., et al. (2015). Shape study of the N = Z nucleus Kr-72 via beta decay. Phys. Rev. C, 92(5), 054326–10pp.
Abstract: The beta decay of the N = Z nucleus Kr-72 has been studied with the total absorption spectroscopy technique at ISOLDE (CERN). A total B(GT) = 0.79(4)g(A)(2)/4 pi has been found up to an excitation energy of 2.7 MeV. The B(GT) distribution obtained is compared with predictions from state-of-the-art theoretical calculations to learn about the ground state deformation of Kr-72. Although a dominant oblate deformation is suggested by direct comparison with quasiparticle random phase approximation (QRPA) calculations, beyond-mean-field and shell-model calculations favor a large oblate-prolate mixing in the ground state.
|
|
|
|
Gottardo, A. et al, Gadea, A., & Algora, A. (2019). New spectroscopic information on Tl-211,Tl-213: A changing structure beyond the N=126 shell closure. Phys. Rev. C, 99(5), 054326–7pp.
Abstract: The neutron-rich isotopes Tl-211,Tl-213, beyond the N = 126 shell closure, have been studied for the first time in isomer gamma-ray decay, exploiting the fragmentation of a primary uranium beam at the Fragment Separator-Rare Isotopes Investigation at GSI setup. The observed isomeric states in Tl-211,Tl-213 show a deviation from the seniority-like scheme of Tl-209. The possible interpretation of the data is discussed on the basis of energy-level systematics and shell-model calculations.
|
|
