Cosmic ray neutron background reduction using localized coincidence veto neutron counting

Patent · Tue Jan 01 00:00:00 EST 2002

OSTI ID:874590

Menlove, Howard O ^[1]; Bourret, Steven C ^[1]; Krick, Merlyn S ^[1]

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1. Los Alamos, NM

This invention relates to both the apparatus and method for increasing the sensitivity of measuring the amount of radioactive material in waste by reducing the interference caused by cosmic ray generated neutrons. The apparatus includes: (a) a plurality of neutron detectors, each of the detectors including means for generating a pulse in response to the detection of a neutron; and (b) means, coupled to each of the neutrons detectors, for counting only some of the pulses from each of the detectors, whether cosmic ray or fission generated. The means for counting includes a means that, after counting one of the pulses, vetos the counting of additional pulses for a prescribed period of time. The prescribed period of time is between 50 and 200 .mu.s. In the preferred embodiment the prescribed period of time is 128 .mu.s. The veto means can be an electronic circuit which includes a leading edge pulse generator which passes a pulse but blocks any subsequent pulse for a period of between 50 and 200 .mu.s. Alternately, the veto means is a software program which includes means for tagging each of the pulses from each of the detectors for both time and position, means for counting one of the pulses from a particular position, and means for rejecting those of the pulses which originate from the particular position and in a time interval on the order of the neutron die-away time in polyethylene or other shield material. The neutron detectors are grouped in pods, preferably at least 10. The apparatus also includes means for vetoing the counting of coincidence pulses from all of the detectors included in each of the pods which are adjacent to the pod which includes the detector which produced the pulse which was counted.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• Assignee: The Regents of the University of California (Oakland, CA)
• Patent Number(s): US 6420712
• OSTI ID: 874590
• Country of Publication: United States
• Language: English

Related Subjects

cosmic
ray
neutron
background
reduction
localized
coincidence
veto
counting
relates
apparatus
method
increasing
sensitivity
measuring
amount
radioactive
material
waste
reducing
interference
caused
generated
neutrons
plurality
detectors
including
means
generating
pulse
response
detection
coupled
pulses
fission
vetos
additional
prescribed
period
time
50
200
embodiment
128
electronic
circuit
leading
edge
generator
passes
blocks
subsequent
alternately
software
tagging
position
rejecting
originate
interval
die-away
polyethylene
shield
pods
10
vetoing
included
adjacent
pod
detector
produced
counted
leading edge
neutron count
/250/