Compton suppression

Landsberger S, and Peshev S (1996) Compton suppression neutron activation analysis Past, present and future. J Radioanal Nud Chem 202 201-224. 

Landsberger S, Swift G, and Neuhoff J (1990) Nondestructive determination of arsenic in urine by epithermal neutron activation analysis and Compton suppression. Biol Trace Elem Res 26-27 27-32. 

James WD, Boothe PN, Presley BJ (1998) Compton suppression garmna-spectroscopy in the analysis of radium and lead isotopes in ocean sediments. J Radioanal Nucl Chem 236 261-265 Jarvis KE, Gray AL, Houk RS (1992) Handbook of Inductively Coupled Plasma Mass Spectrometry, Blackie, Glasgow... 

A number of special techniques have evolved to increase the detection sensitivity in y-ray counting. One of the most important is the suppression of the Compton scattering events in the y-ray spectrum by the use of anticoincidence annulus around the central y-ray detector. The idea behind a Compton suppression spectrometer is that most events in which the incident photon undergoes one or more Compton scattering events in the central detector will result in partial energy deposition in the detector with a low-energy photon escaping the detector. 

This isotope has been determined in soil by low-level Compton suppression y-counting [1]. 

Ge detectors each provided with a cylindrical BGO + Nal Compton suppression shield. The conversion electrons were measured with two spectrometers each consisting of a mini orange filter and a Si(Li) detector. The transmission of the filter was optimized for detection of electrons with energies in the range 0.9- 1.3 MeV. For 196Pb the intensity of the E0 0t transition+in +... 

The y-ray spectra were taken with two Ge detectors both positioned at 135° with respect to the beam direction at the target position. One of the Ge detectors was provided with a BGO Compton suppression shield. 

Measurements were taken on 158Er at a total of 14 target-stopper distances. A portion of the total-projected spectra taken at four of the target-stopper separations is shown in Fig. 1. These spectra are of excellent statistical quality and reveal a favorable peak-to-background ratio in the 0° detector as a result of using the Compton suppression shield. 

The y-ray spectroscopic information was obtained using an array of five Ge detectors with pentagonal Nal anti-Compton shields located at 63° to the beam and three additional Ge detectors at 24°. Two-fold or higher coincident events from these detectors were used to trigger the 72 Nal detectors of the Spin Spectrometer (SS) at ORNL. [JAA83] An average Compton suppression factor of 3.5 for the Co spectrum was obtained. The Ge detectors were placed at 20.8 cm from the target. 

When it reaches its full capability, TASCC will accelerate all ions between lithium and uranium to energies up to 50 MeV/u and 10 MeV/u, respectively, It will feed some major pieces of apparatus the Q3D magnetic spectrometer, the isotope separator, a growing array of gas and solid-state detectors housed in a 1.5 m diameter scattering chamber, and the 8ir" Y-ray spectrometer [AND 84], All are currently operational except the 8ir spectrometer, which is being built by a consortium of Canadian universities and AECL Chalk River, with completion scheduled for late 1986. It will comprise two subsystems i) a spin spectrometer of 72 bismuth germanate (BGO) detectors, and ii) an array of 20 Compton-suppressed hyperpure (HP) Ge detectors. 

Fig. 3. Portion of the 108Pd(a,2nY) 10Cd gamma-ray spectrum observed a) with a single diode and b) with the Compton suppression spectrometer. Some transitions are identified by their energy in keV.

C19. Cooper, J. A., Evaluation of lithium-drifted germanium Compton-suppression spectrometers for non-destructive radiochemical analysis. J. Radioanal. Chem. 6, 177-184 (1970). 

Landsberger S and Wu D (1995) The impact of heavy metals from environmental tobacco smoke on indoor air quality as determined by Compton suppression neutron activation analysis. Sd Total Environ 173/174 323-337. 

The Compton continuum, present in gamma energy spectra recorded either by a Nal(Tl) scintillator or by a Ge detector, is a nuisance that impedes the analysis of complex spectra. It is therefore desirable to eliminate or at least reduce that part of the spectrum relative to the gamma energy peak. One way to achieve this is to use two detectors and operate them in anticoincidence. Such an arrangement, known as the Compton-suppression spectrometer, is shown in Fig. 12.9. A large NaI(Tl) scintillator surrounds a Ge detector, and the two detectors are operated in anticoincidence. The energy spectrum of the central... 

Figure 12.9 Diagram of a Compton suppression spectrometer using a Nal(Tl) and a Ge detector. The two detectors are operated in anticoincidence, with the Ge recording the energy spectrum.

Figure 12.10 The Co spectrum recorded with and without Compton suppression. Notice that the ordinate is in logarithmic scale.

Figure 8.3. Schematic drawing of an anticoincidence system for Compton suppression.

The field deployable tritium analysis system (FDTAS) (Hofstetter et al., 1999) samples water, purifies the sample, and performs Compton-suppressed LS counting to achieve laboratory-quality analyses. The system described by Fig. 15.10 has remote reporting and control capability. 

The normal and Compton-suppressed spectra of with the gamma energies of 1,369 keV and... 

The room-background data discussed here are based on a week-long measurement performed using the Compton-suppressed HPGe detector in Budapest (Belgya et al. 2003 Belgya et al. 1997 Revay et al. 2004). The majority of the peaks originate from the natural radioactive decay chains, i.e., the Th, Np series, and K. These nuclides are in... 

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