ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
The signal processing electronics used for the NE451 detectors on the TFTR multichannel neutron collimator are presently showing saturation effects at high counting rates equivalent to neutron yields of ∼1016 n/s. While nonlinearity due to pulse pileup can be corrected for in most present TFTR experiments, additional steps are required for neutron source strengths above ∼3×1016 n/s. These pulse pileup effects could be reduced by inserting sleeves in the collimator shielding to reduce the neutron flux in the vicinity of the detectors or by reducing the volume of detector exposed to the flux. We describe a novel method of avoiding saturation by optically controlling the number neutron events processed by the detector electronics. Because of the optical opacity of the ZnS-plastic detectors such as NE451, photons from a proton-recoil scintillation arise from a spatially localized area of the detector. By imaging a selected portion of the detector onto a photomultiplier, we reduce the effective volume of the detector in a controllable, reversible way. A prototype system, consisting of a focusing lens, a field lens, and a variable aperture, has been constructed. Results of laboratory feasibility tests are presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1143713
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