Decay of the high-spin isomers inHo150,151,152

Abstract

The electron-capture decay properties of the high-spin isomers in " """Ho were investigated. The nuclides were produced in ', 8 bombardments of samarium and then transported to shielded areas with the use of gasjet systems. Singles and coincidence y-ray measurements were made. Each isomer decays primarily to one excited state in its dysprosium daughter by means of an allowed P transition (logft values are -4.5). The following explanations are proposed, For " Ho and '"Ho the transitions connect 9+(mh]&(2 vf7j2) levels with 8+ (vh9 ]2 Mfa (2) levels in " By(240 1 .8 keV) and ' "Dy(2437.6 keV). Deexcitation to the ground states then follows via a cascade of four E2 y rays. In '"Ho the P transition represents the changeover of an II»" proton orbital to an h9/2 neutron orbital in "'Dy. This single neutron state lies at 527.4 keV and deexcites directly to the ground state. The a decay of '"Ho was also investigated with the use of an on-line isotope separator. Its a-decay branching ratio was determined to be 10.5+ 3.0%%uo. l RADIOACTIVITY "'"Ho, "Ho, "Ho; Ineasured T&/2, F~, I, yy coin; By, '5'. )y, ' Dy deduced level.~&,~J". Ho; measured. I, I,, deduced o.-decay branching ratio: M.ass sepal" atlGIl.

New results in the decay of150Ho and152Tm

“…1) are assigned to the cascade from the 2402.0 keV, 8 + state to the 0 + groundstate of 15~ (Fig 2). Our measurements of the three first transitions give a single half-life of T1/2 =24_+ 1 s in agreement, within the limit of errors with previous reports [5]. But for the 803.7keV transition, corresponding to the 2 + ~ 0 + de-excitation of 1 ~ODy ' we observed a composite decay curve (Fig.…”

High spin levels in151Ho

“…Tentative assignments were made: U=ll/2-and 5/2 + to the ground (T1/2 = 36 s) and low-energy metastable (T1/2 =42 s) states, respectively. Toth et al [7] attributed an 11/2-spin to the 36-second state from the logft value of the/% decay branch to the h9/2 neutron state in ~51Dy.…”

“…Moreover, comparisons with neighbouring nuclei whose structure is already rather convincingly established could be useful in the understanding of level patterns. We report here on a * Work performed within the Grenoble-Swierk collaboration, operating under IN2 P3-Warsaw University agreement detailed study of 151Ho for which preliminary results have been given by us previously [4] and for which only e and r properties were known [5][6][7].…”

Beta-delayed gammas and QEC-values in the decays of150m,152mHo and149Dy

“…decay [14,15]. From the intensity of the 591 keV y-ray of 1 sOgHo in the singles spectrum and the relative intensities of the 591, 653, and 803 keV transitions in 15~ decay [16] a 3.6% feeding of the 803 keV level and a 0.6% feeding of the 1457 keV level from 15~ decay in our measurement were deduced.…”