Beta- and gamma-decay studies of neutron-rich chromium, manganese, cobalt and nickel isotopes including the new isotopes 60Cr and 60gMn

The neutron-rich cobalt isotopes up to A = 67 have been studied through multinucleon transfer reactions by bombarding a 238 U target with a 460-MeV 70 Zn beam. Unambiguous identification of prompt γ rays belonging to each nucleus has been achieved using coincidence relationships with the ions detected in a high-acceptance magnetic spectrometer. The new data are discussed in terms of the systematics of the cobalt isotopes and interpreted with large-scale shell-model calculations in the fpgd model space. In particular, very different shapes can be described in 67 Co, at the edge of the island of inversion at N = 40, where a low-lying highly deformed band coexists with a spherical structure.

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“…[29]. This (7/2 − ) assignment is consistent with the systematics of the lighter odd-mass cobalt isotopes.…”

Section: B the 65 Co Isotopesupporting

confidence: 69%

Spectroscopy of odd-mass cobalt isotopes toward theN=40subshell closure and shell-model description of spherical and deformed states

Recchia¹,

Lenzi²,

Lunardi³

et al. 2012

Phys. Rev. C

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“…The ISOLTRAP value for the mass of 58 Mn is now the sole input to the new AME, due to its small uncertainty. 59 Mn The mass of 59 59 Mn reaction energy of −19610(30) keV was used in AME2003, which combined with the most recent mass value of 64 Ni, resulted in a mass excess of −55480(30) keV. Our result yields a corresponding reaction energy of −19563.4(2.6) keV, moving the Kashy et al result 1.6σ from ours.…”

Section: Resultssupporting

confidence: 41%

“…A clear improvement of the experimental uncertainties, mainly due to improved statistics, can be distinguished between the first and the second experimental runs. As an example, the statistical uncertainty of the 63 Mn frequency ratio was 8.1 × 10 −8 in the first run while in the second run the 64 Mn statistical uncertainty was 4.4 × 10 −8 . Unfortunately, due to the drop in the production yield of 66 Mn associated with the total transport efficiency and the decay loss due to the short half-life (64 ms), the uncertainty of 66 Mn is the largest.…”

Section: Resultsmentioning

confidence: 99%

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Surveying theN=40island of inversion with new manganese masses

et al. 2012

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High-precision mass measurements of neutron-rich 57−66 Mn and 61−63 Fe isotopes are reported. The new mass surface shows no shell closure at N = 40. In contrast, there is an increase of the two-neutron separation energy at N = 38. This behavior is consistent with the onset of collectivity due to the occupation of intruder states from higher orbits, in analogy with the well known "island of inversion" around N = 20. Our results indicate that the neutron-rich Mn isotopes, starting from 63 Mn, are most likely within the new island of inversion. From the new mass surface, we evaluate the empirical proton-neutron interaction and the pairing gap, both playing a significant role in the structural changes in this region.

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mentioning

confidence: 99%

Production of beams of neutron-rich nuclei between Ca and Ni using the ion-guide technique

Perajärvi¹,

Cerny²,

Hager³

et al.

The 4th International Conference on Exotic Nuclei and Atomic Masses

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Abstract.Since several elements between Z=20-28 are refractory in their nature, their neutron-rich isotopes are rarely available as low energy Radioactive Ion Beams (RIB) in ordinary Isotope Separator On-Line facilities [1][2][3][4]. These low energy RIBs would be especially interesting to have available under conditions which allow high-resolution betadecay spectroscopy, ion-trapping and laser-spectroscopy. As an example, availability of these beams would open a way for research which could produce interesting and important data on neutron-rich nuclei around the doubly magic 78 Ni. One way to overcome the intrinsic difficulty of producing these beams is to rely on the chemically unselective Ion Guide Isotope Separator On-Line (IGISOL) technique [5]. Quasi-and deep-inelastic reactions, such as 197 Au( 65 Cu,X)Y, could be used to produce these nuclei in existing IGISOL facilities, but before they can be successfully incorporated into the IGISOL concept their kinematics must be well understood. Therefore the reaction kinematics part of this study was first performed at the Lawrence Berkeley National Laboratory using its 88" cyclotron and, based on those results, a specialized target chamber was built, see Fig. 1 [6].The target chamber shown in Fig. 1 was recently tested on-line at the Jyväskylä IGISOL facility. Yields of massseparated radioactive projectile-like species such as 62,63 Co are about 0.8 ions/s/pnA, corresponding to about 0.06 % of the total IGISOL efficiency for the products that hit the Ni-degrader, see Fig.1. (The current maximum 443 MeV 65 Cu beam intensity at Jyväskylä is about 20 pnA.) This total IGISOL efficiency is a product of two coupled loss factors, namely inadequate thermalization and the intrinsic IGISOL efficiency. In our now tested chamber, about 9 % of the Co recoils are thermalized in the flowing He gas (p He =300 mbar) and about 0.7 % of them are converted into the mass-separated ion beams.In the future, both of these physical/chemical conditions can be suppressed by introducing Ar as a buffer gas and by relying on selective laser re-ionization. This combination will produce isobarically pure beams and it will increase the existing yields by at least a factor of 100, making this overall approach to the study of neutron rich nuclei even more attractive.

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Beta- and gamma-decay studies of neutron-rich chromium, manganese, cobalt and nickel isotopes including the new isotopes 60Cr and 60gMn

Cited by 61 publications

References 23 publications

Spectroscopy of odd-mass cobalt isotopes toward theN=40subshell closure and shell-model description of spherical and deformed states

Spectroscopy of odd-mass cobalt isotopes toward theN=40subshell closure and shell-model description of spherical and deformed states

Surveying theN=40island of inversion with new manganese masses

Production of beams of neutron-rich nuclei between Ca and Ni using the ion-guide technique

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