Standardization of 192Ir

Methods for primary standardization of activity

“…Hence, this is truly a 4π solid angle method for particles and photons with a very high total efficiency for most nuclides. It is well suited for the standardization of radionuclides with a complex decay [54,66], but also for pure β-and α-decay [17][18][19] and even electron capture [67]. Limitations are the rather high noise level, equivalent to an energy threshold of about 10 keV, and the escape probability of high-energy photons.…”

Assessment of the uncertainty budget associated with 4πγcounting

“…The most commonly used detector for 4πγ counting is a large well-type NaI(Tl) detector; various dimensions are given in the literature (152.4 mm × 152.4 mm [10], 75 mm × 75 mm [11], 127 mm × 127 mm [12], 152 mm × 127 mm [13]) and also larger crystals have been installed (e.g. 203 mm × 203 mm at the JRC-IRMM).…”

“…In those cases, pulses delivered by both detectors are first summed in coincidence before feeding the electronic chain. An existing configuration consists of sandwiching the source between two windowless Cs(Tl) crystals, which offers the possibility to measure particles in coincidence with γ and x rays [10,14].…”

“…The branching ratios are a 1 = 0.0964(9) and a 2 = 0.9030 (9), respectively. The detection efficiency (equation (1)) is calculated from the nondetection probabilities of the photons and particles involved: (10) The contributions from EC and bremsstrahlung are generally negligible, so that both branches are detected via the γ ray, but the β + branch has the additional probability of the annihilation photons being detected. If the gamma detection efficiency is high, the difference between the detection efficiency in both branches is small and the activity determination is almost insensitive to uncertainty in the branching ratio.…”

“…Three 4πγ counting instruments were used: the CsI(Tl) sandwich spectrometer [14], an old 152.4 mm × 152.4 mm [10] and a new 203 mm × 203 mm NaI(Tl) well detector. It was the first application with the new detector, whereas the others had been used before to standardize, e.g.…”