Determination of the half-life of the longer-lived 166Ho isomer

Purification of a 166mHo solution by successive high-performance liquid chromatography and gravitational chromatography for half-life determination

“…During the analytical session, the erbium sensitivity was found to be around 9 V/ppm by using Ar in the collision-reaction cell of the instrument. Before measurements, the recovered fractions from chromatography were evaporated to dryness and then dissolved in HNO 3 …”

“…The second is the metastable 166m Ho, used as a reference source for ionization chambers, since it provides a high detection efficiency due to the emission of several photons [2]. Its half-life was measured in 1965 and found to be 1,200 years with a high relative standard uncertainty of 15 % [3].…”

Measurement of Thermal Neutron Capture Cross Section and Resonance Integral of the 166mHo(n, .GAMMA.)167Ho Reaction using a Two-Step Irradiation Technique.

“…Figure 1 shows the reaction chains of the sample in the reactor. Since the activity of 166g Ho (half-life: 26.83 h 12) ) was too large in comparison with that of 166m Ho (half-life: 1,200 yr 7) ), the irradiated samples were cooled for 3 months in order to reduce the activity of 166g Ho. The activities of 166m Ho produced in the sample foils were determined by measuring the γ -ray intensities of 166m Ho from the sample foils using a high purity Ge detector.…”

“…In this regard, the present authors have measured the σ 0 and the I 0 of the important FP nuclides, such as 137 Cs, 1,2) 90 Sr, 3) 99 Tc, 4) 129 I 5) and 135 Cs. 6) Holmium-166m is also a long-lived fission product, whose half-life is 1,200 yr. 7) There is no experimental data of the σ 0 and the I 0 for 166m Ho, except the resonance parameters measured by Masyanov et al, 8) the effective capture cross section (σ ) measured by Harada et al, 9) and theσ measured by Krane. 10) Masyanov et al 8) identified three resonances of 166m Ho in the energy range from 0.001 eV to 137 eV, and calculated from the resonance parameters the σ 0 of 166m Ho to be 9.14±0.65 kb and the I 0 1.14±0.09 kb.…”

Measurement of Thermal Neutron Capture Cross Section and Resonance Integral of the166mHo(n, γ167Ho Reaction using a Two-Step Irradiation Technique

“…In this regard, the present authors have measured the σ 0 and the I 0 of the important FP nuclides, such as 137 Cs, 1, 2) 90 Sr, 3) 99 Tc, 4) 129 I 5) and 135 Cs. 6) Holmium-166m is also a long-lived fission product, whose half-life is 1,200 yr. 7) There is no experimental data of the σ 0 and the I 0 for 166m Ho, except the resonance parameters measured by Masyanov et al, 8) the effective capture cross section (σ ) measured by Harada et al,9) and theσ measured by Krane. 10) Masyanov et al 8) identified three resonances of 166m Ho in the energy range from 0.001 eV to 137 eV, and calculated from the resonance parameters the σ 0 of 166m Ho to be 9.14±0.65 kb and the I 0 1.14±0.09 kb.…”