First beta-decay spectroscopy of In-135 and new beta-decay branches of In-134

Identification of the crossing point at N=21 between normal and intruder configurations

The β− decay of 34Mg was used to study the 34Al nucleus through γ spectroscopy at the Isotope Separator OnLine facility of CERN. Previous studies identified two β-decaying states in 34Al having spin-parity assignments J π = 4− dominated by the normal configuration π(d5/2) −1 ⊗ ν(f7/2) and J π = 1+ by the intruder configuration π(d5/2) −1 ⊗ ν(d3/2) −1(f7/2) 2. Their unknown ordering and relative energy have been the subject of debate for the placement of 34Al inside or outside the N = 20 “island of inversion.” We report here that the 1+ intruder lies only 46.6 keV above the 4− ground state. In addition, a new half-life of T1/2 = 44.9(4) ms, that is twice as long as the previously measured 20…

β decay of 133In : γ emission from neutron-unbound states in 133Sn

Excited states in 133Sn were investigated through the β decay of 133In at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for 133In, allowing us to study separately, and in detail, the β-decay branch of 133In Jπ = (9/2+) ground state and its Jπ = (1/2−) isomer. Thanks to the large spin difference of the two β-decaying states of 133In, it is possible to investigate separately the lower and higher spin states in the daughter, 133Sn, and thus to probe independently different single-particle and single-hole levels. We report here new γ transitions observed in the decay of 133In, including those assigned to the deexcitation of th…

Identification of the crossing point at N=21 between normal and intruder configurations

R. Lica et al. -- 6 pags., 3 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0

Fast-timing study of the l-forbidden 1/2+ -> 3/2+ M1 transition in 129Sn

The levels in 129Sn populated from the β− decay of 129In isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 1/2+ state and the 3/2+ ground state in 129Sn are expected to have configurations dominated by the neutron s1/2 (l = 0) and d3/2 (l = 2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we have measured the half-life of the 1/2+ 315.3-keV state, T1/2 = 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effect…

Normal and intruder configurations in 34Si populated in the β- decay of 34Mg and 34Al

The structure of 34Si was studied through γ spectroscopy separately in the β− decays of 34Mg and 34Al at the ISOLDE facility of CERN. Different configurations in 34Si were populated independently from the two recently identified β-decaying states in 34Al having spin-parity assignments Jπ=4− dominated by the normal configuration π(d5/2)−1⊗ν(f7/2) and Jπ=1+ by the intruder configuration π(d5/2)−1⊗ν(d3/2)−1(f7/2)2. The paper reports on spectroscopic properties of 34Si such as an extended level scheme, spin and parity assignments based on log(ft) values and γ-ray branching ratios, absolute β feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 tr…

Detailed spectroscopy of doubly magic 132Sn

The structure of the doubly magic Sn-132(50)82 has been investigated at the ISOLDE facility at CERN, populated both by the beta(-) decay of In-132 and beta(-)-delayed neutron emission of In-133. The level scheme of Sn-13(2) is greatly expanded with the addition of 68 gamma transitions and 17 levels observed for the first time in the beta decay. The information on the excited structure is completed by new gamma transitions and states populated in the beta-n decay of In-133. Improved delayed neutron emission probabilities are obtained both for In-132 and In-133. Level lifetimes are measured via the advanced time-delayed beta gamma gamma(t) fast-timing method. An interpretation of the level st…

Beta-delayed proton emission from Mg-20

New beta-decaying state in Bi-214

13 pags., 7 figs., 3 tabs.