Cs134/Cs137 Geiger Counter/Gamma Ray Spectrometry

Spectrometry of Cs134 and Cs137 from nuclear reactor accident

Cs134 has peaks at 569, 604, 795, and 801keV.
Cs137 has a peak at 661keV.

Cs134+Cs137 spectrum with iMetry

iMetry is a basic spectrometer, uses a big scintillator for high sensitivity, but that cause lower energy resolution than professional equipments. Thus, Cs134's spectrum peaks, 569, 604keV and Cs137's 661keV are combined and appear as one wide peak.
Cs134 also emits beta ray, but iMetry's closure, 1mm thick in front and back, 2mm in other sides, is sufficient for blocking beta ray of Cs134, not causing any disturbance on measurement. In addition, raise observed lower than Cs134 and Cs137's 600keV peak is derived from gamma ray's back scattering, not from beta rays.

Peak around 600keV

It's up to blend ratio of Cs134 and Cs137, how much keVs would the combined peak be, but must be somewhere between their characteristic peaks of 600keV and 661keV. So, verifying the existence of Cs134 only with this combined peak is difficult, but you may guess Cs134/137 blend ratio and detect Cs134/137 mixed spectrum when examined with 800keV peak derived from Cs134.

Yellow guide is displayed around 600keV
Linear Logarithmic
Cs134_600_liner.png Cs134_600_log.png

Peak around 800keV

As Cs134's other spectrum peaks, 795 and 801keV are not observed in Cs137, if peak around 800keV is observed, existence of Cs134 can be verified.

Yellow guide is displayed around 800keV
Linear Logarithmic
Cs134_800_liner.png Cs134_800_log.png

With Cs134 and Cs137 mixed samples, you may observe 2 peaks around 600keV and 800keV. As Cs134's half life is much shorter than that of Cs137, Cs137 may become dominant as years elapsed from its generation.

  • 最終更新:2013-06-16 22:22:13