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Abstract An in-beam gamma-ray spectroscopy study of the even–even nucleus92Mo has been carried out using the30Si +65Cu,18O +80Se reactions at beam energies of 120 and 99 MeV, respectively. Angular distribution from the oriented state ratio (RADO) and linear polarization (Δasym) measurements have fixed most of the tentatively assigned spin-parity of the high-energy levels. A large-scale shell-model calculation using the GWBXG interaction has been carried out to understand the configuration and structure of both positive and negative parity states up to the highest observed spin. The high-spin states primarily originate from the coupling of excited proton- and neutron-core structures in an almost stretched manner. The systematics of the energy required to form a neutron particle-hole pair excitation,νg9/2→νd5/2, is discussed. The lifetimes of a few high-spin states have been measured using the Doppler shift attenuation method. Additionally, a qualitative argument is proposed to explain the comparatively strong E1 transition feeding the 7310.9 keV level.
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This content will become publicly available on August 22, 2026
63 Fe– 63 Mn: A Possible Strong Urca Pair and Its Potential Astrophysical Impact
Abstract The cooling strength of the Urca pair,63Fe–63Mn, exhibits an extensive range of variation due to the uncertainty in the spin parity of the ground state of63Fe. To investigate the cooling effect of this Urca pair on the thermal evolution of neutron star crusts, we performed simulations on neutron star structure and evolution under various spin-parity assignment scenarios. When adopting recently evaluated nuclear data,63Fe–63Mn emerges as one of the strongest Urca pairs. In the case of MAXI J0556-332,63Fe–63Mn is the only pair above the shallow heating layer, significantly impacting the cooling curve and the superburst ignition. Moreover, the constraint on the past nucleosynthesis reduced to one-quarter of its original value, falling within three decades, which enables the validation of nuclear reaction theories in the outer layers of neutron stars. Our results highlight the need for more precise measurements of theβ−decay of63Mn to better determine the Urca cooling effect of the63Fe–63Mn pair in accreted neutron star crusts.
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- Award ID(s):
- 1927130
- PAR ID:
- 10649164
- Publisher / Repository:
- IOP
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 990
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 13
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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