The development of {sup 3}He neutron detectors for applications in high level gamma-ray backgrounds
To measure high-level-activity scrap and waste, it is necessary to use neutron detectors that are insensitive to the high gamma-ray background. We have developed a combination of {sup 3}He tubes and custom preamplifiers to provide the high efficiency associated with {sup 3}He detectors with good gamma-ray rejection. We have preamplifiers with short time constants in the signal processing to help separate the neutron signals from the slower risetime gamma signals. We have compared AMPTEK (A-111) preamplifiers with Precision Data Technology (PDT 110A) preamplifiers with experimental tests for gamma rejection and radiation damage. Hot cell radiation tests using a 4.5 Ci radium source were performed using {sup 10}B and {sup 3}He detectors to evaluate relative efficiency and the ability to separate neutrons and gamma rays. The AMPTEK A-111 and PDT-110A amplifiers were exposed to gamma doses between {approximately}0.1 R/h and 1500 R/h to observe where the gamma pileup would interfere with the neutron counting. The conclusion is that both amplifiers can operate in gamma fields up to {approximately}500 R/h with modest loss of neutron efficiency. This is valid for the case of only one {sup 3}He tube (30-cm active length) connected to a single amplifier. If an amplifier services multiple tubes or longer tubes, the gamma rejection will get worse. Studies are in progress to determine the lifetime of the amplifiers and {sup 3}He tubes in the high-radiation fields.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 187227
- Report Number(s):
- LA-UR-95-3449; CONF-951091-9; ON: DE96003146
- Resource Relation:
- Conference: 4. nondestructive assay and nondestructive examination waste characterization conference, Salt Lake City, UT (United States), 24-26 Oct 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
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