A simple crystal spectrometer for low-energy photons emitted from radioactive sources, Part II

Further developing our previous crystal spectrometer, a new spectrometer has been fabricated for observing lowenergy photons (2–5 keV) emitted from radioactive sources. The absorption of such low-energy photons in air has been diminished by flowing hydrogen gas in a chamber, inside which the spectrometer is mounted. Large background counts caused by electrons from the source have been greatly decreased by a small magnet placed in front of the source. With the present spectrometer, we have succeeded in high-resolution observation of photons of very weak intensity in radiations emitted from the β-active nuclide 35S, i.e., the 2.62 keV Cl K X rays which are emitted as a result of filling up K-holes produced by the K-shell internal ionization and excitation during the β decay of 35S.