Precise γ-ray energies for calibration of Ge semiconductor spectrometers to 3.5 MeV

Abstract

Precise measurements with Ge(Li) detectors of γ-ray energies from several radionuclides that are useful as calibration standards in Ge semiconductor spectroscopy have been extended up to 3.5 MeV. The technique generally employed has utilized cascade-crossover combinations, with the energies of the cascade γ-rays being measured relative to other close-lying γ-rays whose energies were already known and the energy of the crossover γ-ray being computed from the cascade sum. All the energies are referenced, in a traceable manner, to the 198Au γ-ray energy value of 411.80441 keV recently measured at the National Bureau of Standards. Radionuclides for which γ-ray energies are reported include: 24Na, 48V, 56Co, 58Co, 60Co, 82Br, 84Rb, 88Y, 110mAg, 124Sb, 125Sn, 132Cs, 144Ce, 207Bi and 228Th. Typical uncertainties in the measured energies range from 5 to 15 eV between 1.3 and 3.5 MeV.