材料期刊网

175Lu(n,2n) 174m,gLu(n,2n) 173Lu反应在高能中子通量监测中具有重要作用,其产物的放射性活度通常用HPGe探测器测量,这就需要174m,gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误.在主要的评价核数据库中,只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和γ射线的发射几率等衰变数据,其中173Lu的γ射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高,其他评价数据两个数据库非常一致.在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu,174m,gLu的放射性溶液,用激光共振电离质谱(LRIMS)和热表面电离质谱(TIMS)两种同位素稀释法测定了该溶液中173Lu和174m,gLu核素浓度,然后制备测量源在HPGe探测器上进行了近7年的跟踪测量,发现173Lu的半衰期为1.45 a,比目前评价的数据1.37 a高6.1％,636.1 keV γ射线发射几率的偏差最大,比ENDF/B 7.1的评价数据偏高7％.174gLu半衰期的测量结果3.37 a,比评价数据3.31 a高约1.8％,174gLu 76.5 keV和1 241.8 keV γ射线的发射几率比ENDF/B 7.1的评价数据分别低1.87％和12.8％.

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 kcV and 1241.8 keV gamma-rays of 174Lu are 1.87％ and 12.8％ lower than the evaluated data in ENDF/B 7.1,respectively.