China
Africa
Explore chapters and articles related to this topic
Radiation Measurements and Spectroscopy
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Compton suppression is an anti-coincidence method used to enhance the full-energy peaks in a gamma-ray pulse height spectrum. In this method the gamma-ray spectrometer is surrounded by a second detector (or a ring of detectors). For example, a HPGe detector is often used as the spectrometer, with a scintillator detector (or detectors), formed into a ring around the HPGe detector, operated as a coincidence detector. Because the total coincidence energy is of less concern than the recording of a full-energy event in the HPGe detector, low-resolution scintillators with relatively high gamma-ray absorption efficiency are preferred (e.g., BGO and NaI:Tl). With this configuration an incident photon that Compton scatters in the HPGe detector and then escapes has a reasonable chance of subsequently interacting in the surrounding scintillation detector(s). Both interactions occur at almost the same time. The partial photon energy deposited by the Compton scattered photon in the HPGe detector can thus be suppressed by an anti-coincidence gate that accepts only pulses in the HPGe detector that are anti-coincident with pulses in the scintillator(s). Thus, events in the HPGe detector are recorded only if no simultaneous event occurs in the surrounding scintillator detector(s). The resulting HPGe spectrum has a much reduced Compton continuum at all energies, thereby enhancing the full-energy peak in the spectrum. Dramatic improvements in the pulse height spectrum can be achieved [Molnar 2004; Bender et al. [2015]. Example spectra recorded with the technique are shown for LaBr3:Ce in Fig. 20.27 and HPGe in Fig. 20.28, both having an annular NaI:Tl guard detector for the coincidence gate [Bender et al. [2015].
Development of an integrated non-destructive analysis system, Active-N
Published in Journal of Nuclear Science and Technology, 2023
Harufumi Tsuchiya, Yosuke Toh, Akira Ohzu, Kazuyoshi Furutaka, Fumito Kitatani, Makoto Maeda, Masao Komeda
The PGA detector is located above the cavity (Figure 1). Its main detector is a Ge detector whose relative efficiency is 70%. The Ge detector is surrounded by bismuth germanate (Bi4Ge3O12) scintillation detectors for the Compton suppression. These detectors are surrounded by LiFPE (LiF 50 wt%), LiF tiles (6Li enriched to 95 atom%), and lead blocks.