Decays of new nuclides 169Au, 170Hg, 165Pt and the ground state of 165Ir discovered using MARA



Hilton, JB
(2019) Decays of new nuclides 169Au, 170Hg, 165Pt and the ground state of 165Ir discovered using MARA. PhD thesis, University of Liverpool.

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Abstract

New nuclides 169Au, 165Pt and 170Hg and new ground state 165Irg were produced using reactions of 96Ru(78Kr,XpXn) at bombarding energies of 390 MeV and 418 MeV and 92Mo(78Kr,XpYn) at a bombarding energy of 418 MeV. The MARA vacuum mode recoil mass separator was used to separate the new nuclei and implant them into a DSSD instrumented with digital readout electronics to measure their decay properties. The proton-emitting nuclei were identified using digitised preamplifier output ‘traces’, and the method used is discussed in depth. Fifteen proton-decay chains of 169Aum were measured with proton-emission energy Ep = 2182(28) keV and half-life T1/2 = 1.27+0.61−0.57 µs. One α-decay chain of 169Aum was also identified with α-particle energy Eα = 7333(27) keV, which occurred 1.3 µs after the recoil ion was implanted. Combining the data for both decay branches yielded a half-life of 1.16+0.50−0.47 µs and an estimated production cross section of 5 nb for this state in 169Au. Seven proton-decay chains of 165Irg were measured with proton emission energy Ep = 1454(38) keV and T1/2 = 1.20+0.82−0.74 µs. The results are compared with WentzelKramersBrillouin (WKB) calculations.The prospects of observing proton emission from even lighter gold and iridium isotopes are discussed. Four α-decay chains of 165Pt were measured with α-particle energy Eα = 7272(14) keV and T1/2 = 0.26+0.26−0.09 ms, with an assumed α branching ratio of ≈100%. One α-decay chain of 170Hg was measured with Eα = 7590(30) keV and T1/2 = 0.08+0.40−0.04 ms, with an assumed α branching ratio of ≈100%. Comparison of the reduced α-decay widths with systematics indicates that both α decays are unhindered. Although combining the measured α-decay Q values with extrapolated masses suggests that both new nuclides are unbound to 2-proton emission by more than 1 MeV, their α-decay halflives are too short for this decay mode to compete. Improved data were also obtained for the α emitters 166,167Pt, produced via the 96Ru(78Kr,α4n) and 96Ru(78Kr,α3n) reactions at bombarding energies of 390 MeV and 418 MeV, respectively.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Nuclear Physics, Proton Emission, Alpha Decay, Nuclear Structure, MARA, Mass Separator
Divisions: Fac of Science & Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 23 Oct 2019 14:38
Last Modified: 01 Sep 2020 17:34
DOI: 10.17638/03057808
Supervisors:
URI: http://livrepository.liverpool.ac.uk/id/eprint/3057808