Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich Sb51122–131 isotopes

Background: Levels fulfilling the seniority scheme and relevant isomers are commonly observed features in semimagic nuclei; for example, in Sn isotopes (Z=50). Seniority isomers in Sn, with dominantly pure neutron configurations, directly probe the underlying neutron-neutron (νν) interaction. Furthermore, an addition of a valence proton particle or hole, through neutron-proton (νπ) interaction, affects the neutron seniority as well as the angular momentum. Purpose: Benchmark the reproducibility of the experimental observables, like the excitation energies (EX) and the reduced electric-quadrupole transition probabilities [B(E2)], with the results obtained from shell-model interactions for ne…

Direct observation of theBa114→Xe110→Te106→Sn102tripleα-decay chain using position and time correlations

The triple $\ensuremath{\alpha}$-decay chain $^{114}\mathrm{Ba}\ensuremath{\rightarrow}^{110}\mathrm{Xe}\ensuremath{\rightarrow}^{106}\mathrm{Te}\ensuremath{\rightarrow}^{102}\mathrm{Sn}$ has been directly observed for the first time, following the $^{58}\mathrm{Ni}(^{58}\mathrm{Ni},2n)$ reaction. Implantation of $^{114}\mathrm{Ba}$ nuclei into a double-sided silicon-strip detector has allowed their $\ensuremath{\alpha}$ decays to be correlated in position and time with the $\ensuremath{\alpha}$ decays of the daughter $(^{110}\mathrm{Xe})$ and granddaughter $(^{106}\mathrm{Te})$ nuclei. In total, 17 events have been assigned to the $^{114}\mathrm{Ba}\ensuremath{\rightarrow}^{110}\mathrm{Xe}…

Lifetime measurements in Ti52,54 to study shell evolution toward N=32

Lifetimes of the excited states in the neutron-rich Ti-52,Ti-54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance D ...

Direct observation of the Ba 114 → Xe 110 → Te 106 → Sn 102 triple α -decay chain using position and time correlations

The triple α-decay chain 114Ba → 110Xe → 106Te → 102Sn has been directly observed for the first time, following the 58Ni(58Ni ,2n) reaction. Implantation of 114Ba nuclei into a double-sided silicon-strip detector has allowed their α decays to be correlated in position and time with the α decays of the daughter (110Xe) and granddaughter (106Te) nuclei. In total, 17 events have been assigned to the 114Ba → 110Xe → 106Te → 102Sn triple α-decay chain. The energy of the 114Ba α decay has been measured to be Eα = 3480(20) keV, which is 70 keV higher than the previously measured value, and the half-life of 114Ba has been measured with improved accuracy, to be 380+190 −110 ms. A revised Q12C value …

Evidence of octupole-phonons at high spin in 207Pb

A lifetime measurement of the 19/2 state in Pb has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a Pb beam impinging on a Mo enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt γ rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3,19/2→13/2)=40(8) W.u. is the first indication of the octupole phonon at high spin in Pb. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in Pb is compa…

Compton imaging with AGATA and SmartPET for DESPEC

DESPEC (DEcay SPECtroscopy) is a spectrometer, currently under construction, which is to be used at the FAIR (Facility for Antiproton and Ion Research) facility at GSI Darmstadt, Germany, as part of the NuSTAR (Nuclear STructure, Astrophysics and Reactions) project. Its goal is to analyse the decay of exotic nuclei produced via the Super-FRS (SUPERconducting FRagment Separator). The optimal configuration of certain elements of the spectrometer, namely a HPGe (High Purity Germanium) tracking array, is still under consideration. Work currently being carried out at the University of Liverpool using a segmented, coaxial HPGe detector (AGATA B009) and a pixelated, planar HPGe detector (SmartPET …

Pairing-quadrupole interplay in the neutron-deficient tin nuclei: First lifetime measurements of low-lying states in 106,108Sn

The lifetimes of the low-lying excited states 2(+) and 4(+) have been directly measured in the neutron-deficient Sn-106,Sn-108 isotopes. the nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. the emitted gamma rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2; 2(1)(+) -> 0(g.s)(+)) values and it describes well the experimental pattern for Sn104-114 ; the B…

Isospin dependence of electromagnetic transition strengths among an isobaric triplet

*Aydın, Sezgin ( Aksaray, Yazar )

Low-lying electric dipole gamma-continuum for the unstable Fe-62,64 nuclei : Strength evolution with neutron number

6 pags., 4 figs.

Delayed or absent π(h11/2)2 alignment in Xe111

Evidence of Partial Seniority Conservation in the pi g9/2 Shell for the N=50 Isotones

The reduced transition probabilities for the 4-> and 2->0 transitions in 92Mo and 94Ru and for the 4->2 and 6->4 transitions in 90Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f5/2, p3/2, p1/2, and g9/2 proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N=50 g9/2 orbital to be understood. The conclusion is that seniority is largely conserved in the first πg9/2 orbital.

Interaction position resolution simulations and in-beam measurements of the AGATA HPGe detectors

WOS: 000290082600015

AGATA-Advanced GAmma Tracking Array

WOS: 000300864200005

Isospin Properties of Nuclear Pair Correlations from the Level Structure of the Self-Conjugate Nucleus Ru88

The low-lying energy spectrum of the extremely neutron-deficient self-conjugate (N = Z) nuclide 88 44Ru44 has been measured using the combination of the Advanced Gamma Tracking Array (AGATA) spectrometer, the NEDA and Neutron Wall neutron detector arrays, and the DIAMANT charged particle detector array. Excited states in 88Ru were populated via the 54Fe(36Ar; 2n )88Ru fusion-evaporation reaction at the Grand Acc�el�erateur National d'Ions Lourds (GANIL) accelerator complex. The observed -ray cascade is assigned to 88Ru using clean prompt - -2-neutron coincidences in anti-coincidence with the detection of charged particles, con�rming and extending the previously assigned sequence of low-lyin…