Der Zerfall des¹⁶³Tb

Abstract

The beta and gamma radiations of¹⁶³Tb have been investigated employing scintillation and semiconductor spectrometers and coincidence techniques. The sources were produced by the¹⁶³Dy(n,p)¹⁶³Tb reaction. A half-life of 19.5 min has been measured without evidence for an isomeric state in the half-life range of 2 sec to 7 d; especially a 6.5 h activity previously assigned to¹⁶³Tb could not be confirmed. 76 of the total of 82 gamma-ray transitions, representing 99.6% of the gamma-ray intensity, could be assigned to 23 levels in¹⁶³Dy. From beta and beta-gamma coincidence measurements aQβ-value of 1.7 ± 0.1 MeV has been determined. Spin and parity of 3/2⁺ are deduced for the ground state of¹⁶³Tb with the Nilsson configuration [411↑]. The level at 884 keV is interpreted as aJ ^π=1/2⁺ state with a high contribution of the three-quasiparticle configurationp[411↑]-p[523↑]-n[523↓] because of an allowed unhindered beta-ray transition to this level.