Digital positron lifetime spectrometer for measurements of radioactive materials

Influence of different chemical elements on irradiation-induced hardening embrittlement of RPV steels

“…Depending on the radioactivity of the samples, the distance separating the detectors was adjusted to minimize the background. Care was taken to separate correctly the c-peaks coming from the specimens and those related to the positrons, by following the procedure described by Jardin et al [23]. Due to their activation, the acquisition of statistically relevant number of counts, namely at least one million, has required up to one week for each of these high-dose irradiated samples.…”

“…The resolution of the setup was constantly checked to be about 175 ps, while the source contribution was set to 15% with a single lifetime of 393 ps. More detailed information about the experimental setup is given in [23,25]. All measurements were performed at room temperature using a 22 Na positron source, with a strength of 2 MBq, wrapped in Kapton foils.…”

Positron annihilation study of neutron irradiated model alloys and of a reactor pressure vessel steel

“…The main lifetime used within this paper has been measured, but it is very close to the calculated value (s m = I 1 Â s 1 + I 2 Â s 2 ). More detailed information about the experimental setup is given by Jardin et al [18,20]. Here, it has been shown that for our setup, the lifetime measured in non-irradiated pure Fe samples corresponds to (107.57 ± 0.38) ps.…”

“…Depending on the radioactivity of the samples, the distance separating the detectors was adjusted to minimise the background. Care was taken to separate correctly the c-peaks coming from the specimens and those related to the positrons, by following the procedure described by Jardin et al [18]. Due to their activation, the acquisition of statistically relevant number of counts, namely at least one million, has required up to 1 month for these high dose irradiated samples.…”

Digital positron lifetime spectrometer for measurements of radioactive materials

“…A complete discussion of the setup and results can be found in Ref. [7]. Co-source of respectively 6, 12 and 23 MBq.…”