Measurements of Decay Data of ¹⁷³Lu and ^174gLu

Key words: 
• ¹⁷³Lu /
• ¹⁷⁴Lu /
• half life /
• gamma-ray emission probabilities /
• HPGe /

Abstract: ¹⁷⁵Lu(n,2n)^174m,gLu(n,2n)¹⁷³Lu are important neutron reactions to monitor the high energy neutron fluxes and the residual nuclei, ^174m,gLu and ¹⁷³Lu, are usually measured by a HPGe spectrometer conveniently so that the decay data such as half lives and gamma-ray emission probabilities of ^174m,gLu and ¹⁷³Lu must be accurate. There are evaluated decay data only in ENDF/B 7.1 and JEFF 3.1.1 among the major evaluated nuclear data libraries, where the most data are almost same besides the gamma-ray emission probabilities of ¹⁷³Lu are higher in ENDF/B 7.1 than that in JEFF 3.1.1. Yb metal as a target was irradiated by 20 MeV proton beams on a tandem accelerator in CIAE to produce ^174m,gLu and ¹⁷³Lu, and ¹⁷⁶Lu isotopic dilution methods based upon a laser resonance ionization mass spectrometer (LRIMS) and a thermal surface ionization mass spectrometer (TIMS) were employed to determine the numbers of nuclides of ¹⁷⁴Lu and ¹⁷³Lu in a solution containing the irradiated target. Several radioactive sources made from the solution had been measured by a HPGe detector during the past 7 years and the peak intensities of the characteristic gamma-rays from ^174gLu and ¹⁷³Lu were analyzed to determine the half lives and gamma-ray emission probabilities. According to the measurements, the half life of ¹⁷³Lu is 1.45 a, which is about 6.1% longer than the evaluated 1.37 a, and the gamma-ray emission probabilities of ¹⁷³Lu is also different from the evaluated data, especially the emission probability of 636.1 keV gamma-ray of ¹⁷³Lu is 7% higher than the value in ENDF/B 7.1. The half life of ^174gLu is 3.37 a, about 1.8% longer than the evaluated 3.31 a, and the emission probabilities of 76.5 keV and 1 241.8 keV gamma-rays of ¹⁷⁴Lu are 1.87% and 12.8% lower than the evaluated data in ENDF/B 7.1, respectively.