Response of large area avalanche photodiodes to low energy X-rays
Thomas R. Gentile, Uwe Arp, M J. Bales, R Farrell
For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) at liquid nitrogen temperature to detect X-rays with energies between 0.2 keV and 15 keV. Whereas there are numerous reports of X-ray spectrometry using APDs at energies above 1 keV, operation at liquid nitrogen temperature allowed us to reach a nominal threshold of 0.1 keV. However, due to the short penetration depth of X-rays below 1 keV, the pulse height spectrum of the APD become complex. We studied the response using monochromatic X-ray beams and employed phenomenological fits of the pulse height spectrum to model the measurement of a continuum spectrum from a synchrotron. In addition the measured pulse height spectrum was modelled using a profile for the variation in efficiency of collection of photoelectrons with depth into the APD. The best results are obtained with the collection efficiency model.
, Arp, U.
, Bales, M.
and Farrell, R.
Response of large area avalanche photodiodes to low energy X-rays, Review of Scientific Instruments, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=910652
(Accessed March 31, 2023)