7 research outputs found
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Gamma-ray dosimetry measurements of the Little Boy replica
We present the current status of our gamma-ray dosimetry results for the Little Boy replica. Both Geiger-Mueller and thermoluminescent detectors were used in the measurements. Future work is needed to test assumptions made in data analysis
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Neutron dosimetry of the Little Boy device
Neutron dose rates at several angular locations and at distances out to 0.5 mile have been measured during critical operation of the Little Boy replica. We used modified remmetes and thermoluminescent dosimetry techniques for the measurements. The present status of our analysis is presented including estimates of the neutron-dose-relaxation length in air and the variation of the neutron-to-gamma-ray dose ratio with distance from the replica. These results are preliminary and are subject to detector calibration measurements
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Energy response and dose-rate calibration of a Geiger-Mueller gamma-ray detector
To obtain more precise dose-rate measurements, we have taken a commercial gamma-ray dosimeter that uses a Geiger-Mueller (GM) tube as its detector and, by supplying it with an externally regulated high voltage, counted the gamma-ray-induced pulses with suitable scaling and timing circuits. We have now improved the method of calibration by measuring detector response to 13 different sources, each with an independently verified strength, in the energy range from 60 keV to 2.6 MeV. With the use of computer codes, the resulting response curve can be folded into the spectrum of the source to be measured
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Critical commentary on dose-rate evaluations
Survivors of Hiroshima and Nagasaki present a unique problem in dosimetry: the effects of radiation exposure may be inferred although the exposure itself is unknown. Experience with a replica of Little Boy demonstrates the difficulties of measuring dose rates, the problems of comparing measurements with calculations, and the inadequacy of the conventional standards that are used to calibrate dosimeters
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Reactivity coefficients of heavy isotopes in LASL's fast critical assemblies
A systematic investigation of heavy isotope behavior in the Pajarito fast-neutron critical assemblies is described. Included will be central reactivity coefficient measurements and fission rate measurements in natural uranium reflected plutonium and 93%-enriched uranium metal assemblies and in Big Ten, a depleted uranium reflected 10%-enriched uranium metal assembly