The decays of 21.55 min 162gTm and 24.3 s 162Tm (a new isomer)

doi:10.1016/0375-9474(74)90260-7

Nuclear Physics A

Volume 236, Issue 2, 30 December 1974, Pages 349-378

https://doi.org/10.1016/0375-9474(74)90260-7 Get rights and content

Abstract

The decay of the 21.55 min ground state and of the 24.3 s isomeric state of ¹⁶²Tm was investigated with semiconductor detectors. The γ-ray spectrum was investigated with a Compton-suppression Ge(Li)-NaI(Tl) arrangement. A Si (Li) detector, mounted in an electron transport solenoid, was used to investigate the conversion electron spectrum. Three-dimensional coincidence measurements were performed with large-volume Ge(Li) detectors. The ¹⁶²Tm ground state has spin-parity 1⁻ and Nilsson assignment p[411]↓−n[521]↑. An allowed β-transition (log ft ≈ 6.4) was observed to a 2⁻, 2 octupole vibrational level at 1572.84 keV. The Q-value determined from positon-gamma coincidence measurements is 4705 ± 70keV. The discrepancy of the experimental K /β⁺ ratio with theoretical predictions might possibly be explained by a large number of unobserved weak γ-rays besides the total of 315 stronger ones observed in this study. The average β-strength function was calculated to be 1.2 × 10⁻⁵. Among the 50 levels observed in the decay, the 2⁺, 4⁺ and 6⁺ members of the ground-state band, the 2⁺, 3⁺ and 4⁺ members of the γ-band, several 0⁺ and 2⁺ members of the K = 0 β-bands and 1⁻, 2⁻ and 3⁻ octupole vibrational levels were identified. Parameter values Z_γ(0) and Z_γ(2) determining the mixing between the γ-band and the ground-state band, allow no conclusive evidence about unequalness of the intrinsic quadrupole moments of the ground states and the γ-band. The Z(0) parameters, determining the mixing between the β-bands and the ground-state band, and X parameters determining the ratio of E0 to E2 transition probabilities, were deduced. A previously unreported 24.3 sec isomer in ¹⁶²Tm was observed to decay in 10% of the cases by an allowed unhindered (log ft = 4.7) β-ray transition to a level at 1712.20 keV in ¹⁶²Er. The Nilsson configurations assigned to the isomeric and 1712.20 keV levels are p[523]↑ + n[521]↑₅₊ and n[523]↓ + n[521]↑₄₊ respectively. The isomeric level decays in 90% of the cases by an E3 transition (E_IT < 125 keV) to a p[404]↓ −n[521]↑₂₋ level at 66.90 keV in ¹⁶²Tm, which decays by an (M1+ < 40 % E2) to the 21.55 min ¹⁶²Tm 1⁻ ground state.

References (42)

A. Abdumalikov et al.
Phys. Lett.
(1963)
H. Morinaga
Nucl. Phys.
(1966)
A. Johnson et al.
Phys. Lett.
(1971)
P.O. Tjøm et al.
Nucl. Phys.
(1968)
F.W.N. de Boer et al.
Nucl. Phys.
(1971)
J. Konijn et al.
Nucl. Instr.
(1973)
D.C. Camp et al.
Nucl. Phys.
(1971)
E.W.A. Lingeman et al.
Nucl. Instr.
(1974)
J.L. Wood et al.
Nucl. Phys.
(1972)
E.W.A. Lingeman et al.
Nucl. Instr.
(1972)

P.F.A. Goudsmit et al.

Nucl. Phys.

(1972)

C. Ekström et al.

Nucl. Phys.

(1971)

P.F.A. Goudsmit et al.

Nucl. Phys.

(1970)

C.W. Reich et al.

Nucl. Phys.

(1970)

F.W.N. de Boer et al.

Nucl. Phys.

(1974)

B. Fogelberg et al.

Nucl. Phys.

(1971)

K. Neergård et al.

Nucl. Phys.

(1970)

S.B. Burson et al.

Nucl. Phys.

(1973)

A. Charvet et al.

Nucl. Phys.

(1973)

G. Bayer et al.

Y.Y. Chu

Phys. Rev.

(1971)

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The decays of 21.55 min 162gTm and 24.3 s 162Tm (a new isomer)

Abstract

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The decays of 21.55 min ^162gTm and 24.3 s ¹⁶²Tm (a new isomer)