Note

Preparation of long-lived holmium-163☆

The available data from the various reaction and decay studies leading to nuclides having mass number A=163 have been reviewed. These data are summarized and presented, together with adopted level schemes and properties, for nuclides from Eu (Z=63) through Os (Z=76). ¹⁶³Eu represents a new addition to these nuclides. Level structures are now known for ¹⁶³Ta and ¹⁶³W through high-spin studies and recoil-decay tagging techniques. Several radioactive decays in this mass chain are not known at all or poorly established. No β or γ-ray data are available for ¹⁶³Re–¹⁶³W–¹⁶³Ta–¹⁶³Hf ε decay chain. Those for ¹⁶³Hf–¹⁶³Lu–¹⁶³Yb ɛ decay chain and ¹⁶³Eu–¹⁶³Gd–¹⁶³Tb ${\mathrm{\beta }}^{-}$ decay chain are very sketchy. This evaluation is an update and revision of the previous one (2000Si01).

Nuclear spectroscopic information for known nuclides of mass number 163 (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os) has been evaluated and presented together with adopted energies, J??, and decay modes of levels in these nuclei. No data are yet available for excited states inn ¹⁶³Gd, ¹⁶³Ta, ¹⁶³W and ¹⁶³Os. This evaluation represents a revision of earlier Nuclear Data Sheets for A = 163 (1989Bu02, 1980Da03, 1972Bu43).

The IBEC theory has been tested for the case of ¹⁹³Pt. The Q_EC value is 56.3 ± 0.3 keV, and the data make it possible to give an upper limit on the electron neutrino mass of 500 eV (90% C.L.). The partial beta-decay half-life for M capture in ¹⁶³Ho is (4.0 ± 1.2) × 10⁴ y and the ¹⁶³Ho-¹⁶³Dy mass difference is 2.3 ± 1.0 keV. From these independent Ho results a half-life of (7 ± 2) × 10³ y and an upper limit on m_ve of 1.3 keV can be deduced.

The partial beta-decay half-life for capture of M electrons in ¹⁶³Ho is (4.0 ± 1.2) × 10⁴ yr, and the ¹⁶³Ho¹⁶³Dy mass difference is 2.3 ± 1.0 keV. From these independent results we deduce a half-life of (7 ± 2) × 10³ yr and an upper limit on the electron neutrino mass of 1.3 keV.

Nuclear structure data for all nuclei with mass number A=163 have been evaluated. Adopted values for level properties and detailed level and decay schemes are presented for each nucleus, along with the experimental data upon which they are based.

Theoretical (Hager-Seltzer) conversion coefficients for pure multipole transitions are presented without uncertainties. For mixed transitions, the stated conversion-coefficient uncertainties take into account the uncertainty of the mixing ratio as well as the uncertainties of the theoretical conversion coefficients for the pure multipole components (2% for M1, E2, and E1 transitions and 5% for all others).

Nuclear structure data for mass 163 nuclei are compiled, and adopted level and gamma-ray properties are presented. The adopted values are based on all data received before June 1972.