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

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

Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive $^{222}$Ra and $^{228}$Ra Beams

There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of $E$3 matrix elements for different nuclear transitions is explained by describing $^{222}$Ra as pear-shaped with stable octupole deformation, while $^{228}$Ra behaves like an octupole vibrator.

Restoring the valence-shell stabilization in 140Nd

A projectile Coulomb-excitation experiment was performed at the radioactive-ion beam facility HIE-ISOLDE at CERN to obtain $E2$ and $M1$ transition matrix elements of $^{140}$Nd using the multistep Coulomb-excitation code GOSIA. The absolute $M1$ strengths, $\textrm{B}(M1;2^+_2→2^+_1)=0.033(8)μ^2_N,\textrm{B}(M1;2^+_3→2^+_1)=0.26^{+0.11}_{−0.10}μ^2_N$, and $\textrm{B}(M1;2^+_4→2^+_1)<0.04μ^2_{\textrm{N}}$, identify the $2^+_3$ state as the main fragment of the one-quadrupole-phonon proton-neutron mixed-symmetry state of $^{140}$Nd. The degree of F-spin mixing in $^{140}$Nd was quantified with the determination of the mixing matrix element $V_{\textrm{F−mix}}<7^{+13}_{−7}$keV.

The observation of vibrating pear-shapes in radon nuclei (vol 10, 2473, 2019)

Low-energy Coulomb excitation of Fe-62 and Mn-62 following in-beam decay of Mn-62

Collective 2(1)(+) excitations in Po-206 and Rn-208,Rn-210

In the present study, values have been measured in the 208,210Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. These nuclei have been proposed to lie in, or at the boundary of the region where the seniority scheme should persist. However, contributions from collective excitations are likely to be present when moving away from the N=126 closed shell. Such an effect is confirmed by the observed increased collectivity of the transitions. Experimental results have been interpreted with the aid of theoretical studies carried out within the BCS-based QRPA framework. ispartof: European Physical Journal A, Hadrons and Nuclei vo…

Octupole states in 207Tl studied through β decay

The β decay of 207Hg into the single-proton-hole nucleus 207Tl has been studied through γ-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the πs−11/2, πd−13/2, and πh−111/2 shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s1/2-coupled) are identified and three more states (d3/2-coupled) are tentatively assigned using spin-parity inferences, while further h11/2-coupled states may also have been observed for the first time. Comparisons are made with st…

Normal and intruder configurations in $^{34}$Si populated in the $β^-$ decay of $^{34}$Mg and $^{34}$Al

The structure of $^{34}$Si was studied through $\gamma$ spectroscopy separately in the $\beta^-$ decays of $^{34}$Mg and $^{34}$Al at the ISOLDE facility of CERN. Different configurations in $^{34}$Si were populated independently from the two recently identified $\beta$-decaying states in $^{34}$Al having spin-parity assignments $J^\pi = 4^-$ dominated by the normal configuration $\pi (d_{5/2})^{-1} \otimes \nu (f_{7/2})$ and $J^\pi = 1^+$ by the intruder configuration $\pi (d_{5/2})^{-1} \otimes \nu (d_{3/2})^{-1}(f_{7/2})^{2}$. The paper reports on spectroscopic properties of $^{34}$Si such as an extended level scheme, spin and parity assignments based on log($ft$) values and $\gamma$-ray…

Fast-timing study of the l -forbidden 12+→32+ M1 transition in Sn 129 FAST-TIMING STUDY of the l -FORBIDDEN ⋯ R. LICǎ et al.

© 2016 authors. Published by the American Physical Society.The levels in Sn129 populated from the β- decay of In129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 12+ state and the 32+ ground state in Sn129 are expected to have configurations dominated by the neutron s12 (l=0) and d32 (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 12+ 315.3-keV state, T12= 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-…

Beta-delayed proton emission from Mg-20

New beta-decaying state in Bi-214

13 pags., 7 figs., 3 tabs.

(208)po populated through EC/beta(+) decay

The structure of 208Po resulting from the EC/β + decay of 208At was studied at CERN’s ISOLDE Decay Station (IDS). The high statistics afforded by the high yield of 208At and the high efficiency HPGe clusters at the IDS allowed for greater insight into lower intensity transitions and thus significant expansion of the 208Po level scheme. Furthermore, investigation into the isomeric state yielded a new half life 377(9) ns in addition to uncovering new transitions populating the state.