15 research outputs found
Detailed structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>131</mml:mn></mml:mmultiscripts></mml:math> populated in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>ÎČ</mml:mi></mml:math> decay of isomerically purified <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>In</mml:mi><mml:mprescripts/><mml:none/><mml:mn>131</mml:mn></mml:mmultiscripts></mml:math> states
The excited structure of the single-hole nucleus Sn131 populated by the ÎČâ decay of In131 was investigated in detail at the ISOLDE facility at CERN. This new experiment took advantage of isomeric purification capabilities provided by resonant ionization, making it possible to independently study the decay of each isomer for the first time. The position of the first-excited Îœh11/2 neutron-hole state was confirmed via an independent mass spectroscopy experiment performed at the Ion Guide Isotope Separator On-Line facility at the University of JyvĂ€skylĂ€. The level scheme of Sn131 was notably expanded with the addition of 31 new Îł-ray transitions and 22 new excited levels. The Îł-emitting excited levels above the neutron separation energy in Sn131 were investigated, revealing a large number of states, which in some cases decay by transitions to other neutron-unbound states. Our analysis showed the dependence between the population of these states in Sn131 and the ÎČ-decaying In131 state feeding them. Profiting from the isomer selectivity, it was possible to estimate the direct ÎČ feeding to the 3/2+ ground and 11/2â isomeric states, disentangling the contributions from the three indium parent states. This made possible to resolve the discrepancies in logft for first-forbidden transitions observed in previous studies, and to determine the ÎČ-delayed neutron decay probability (Pn) values of each indium isomers independently. The first measurement of subnanosecond lifetimes in Sn131 was performed in this work. A short T1/2=18(4)âps value was measured for the 1/2+ neutron single-hole 332-keV state, which indicates an enhanced l-forbidden M1 behavior for the Îœ3s1/2â1âÎœ3d3/2â1 transition. The measured half-lives of high-energy states populated in the ÎČ decay of the (21/2+) second isomeric state (In131m2) provided valuable information on transition rates, supporting the interpretation of these levels as core-excited states analogous to those observed in the doubly-magic Sn132.
Published by the American Physical Society
2024
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Properties of low-lying states in 65Co from lifetime measurements
© 2019 American Physical Society. The low-energy structure of Co65 was studied by means of Îł-and fast-timing spectroscopy at the ISOLDE/CERN facility. The known level scheme of Co65 populated following the ÎČ-decay of Fe65 was expanded. The experimental results were compared with large-scale shell-model calculations. The measured long lifetime of the (1/21-) level confirms its nature as a highly collective state with proton excitations across the Z=28 gap and neutrons across the N=40 subshell.status: publishe
Search for shape-coexisting 0+ states in 66Ni from lifetime measurements
The lifetime of the 0+3 state in 66Ni, two neutrons below the N=40 subshell gap, has been measured. The transition B(E2;0+3â2+1) is one of the most hindered E2 transitions in the Ni isotopic chain and it implies that, unlike 68Ni, there is a spherical structure at low excitation energy. We have performed extensive shell-model calculations that correctly predict this result, obtaining a spherical 0+ state at the correct energy and with an extremely low B(E2;0+3â2+1) value.status: publishe
Investigation of Low-lying States in 133Sn Populated in the ÎČ Decay of 133In Using Isomer-selective Laser Ionization
Excited states in the neutron-rich isotope 133Sn were studied via the ÎČ decay of 133In. Isomer selective ionization using the ISOLDE RILIS enabled the ÎČ decays of 133Ings (IÏ = 9â2+) and 133mIn (IÏ = 1â2â) to be studied independently for the first time. A description of the experimental setup at the ISOLDE Decay Station is presented together with preliminary results from the experiment.status: publishe