0000000000227388
AUTHOR
P.j.r. Mason
Electromagnetic transition strengths in 109Te
Lifetime measurements have been made in the neutron-deficient nucleus 109Te using the coincident recoil distance Doppler-shift method. The experimental B(E2) values have been compared with state-of-the-art shellmodel calculations using the monopole-corrected realistic charge-dependent Bonn nucleon-nucleon potential. Lifetimes in the νh11/2 band are consistent with an interpretation based on the deformation driving properties of a single valence neutron outside of the even-even tellurium core and highlight the unexpected presence of collective behavior as the N = 50 shell closure is approached. Lifetime measurements for the low-lying positive-parity states also appear to correlate well with …
Characterization of a neutron–beta counting system with beta-delayed neutron emitters
A new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known β-delayed neutron emission properties. The setup consists of BELEN-20, a 4π neutron counter with twenty 3He proportional tubes arranged inside a large polyethylene neutron moderator, a thin Si detector for β counting and a selftriggering digital data acquisition system. The use of delayed-neutron precursors with different neutron emission windows allowed the study of the effect of energy dependency on neutron, β and β-neutron rates. The observed effect is well reproduced by Monte Carlo simulations. The impact of this dependency on the accura…
Recoil-beta tagging study of the N=Z nucleus 66As
An in-beam study has been performed to further investigate the known isomeric decays and to identify T = 1 excited states in the medium-heavy N = Z = 33 nucleus 66As. The fusion-evaporation reaction 40Ca(28Si,pn) 66As was employed at beam energies of 75 and 83 MeV. The half-lives and ordering of two known isomeric states in 66As have been determined with improved accuracy. In addition, several prompt γ -ray transitions from excited states, both bypassing and decaying to the isomeric states in 66As, have been observed. Most importantly, candidates for the 4+ → 2+ and 6+ → 4+ transitions in the T = 1 band have been identified. The results are compared with shell-model calculations using the m…