The theory of self-focusing has been applied to beams propagating in the atmosphere. The effects of density variation, absorption, and air breakdown which limit the self-focusing through power driven instabilities are estimated. It is found that laser pulses whose pulse lengths are between 10 ns and 10 micros with powers from 10(2)P(c) to 10(3)P(c) have a chance to self-focus. Here P(c) is the critical power for self-focusing in an ideal nonattenuating medium with a nonlinear index of refraction.

In the first hours or days after an unplanned release of radioactive material to the environment, the radiation detection instruments most widely available to local first responders may be those currently fielded for interdiction missions. This study investigated how such preventative radiological/nuclear detection instruments could perform if repurposed for consequence management missions. A representative sample of three archetypes (body-worn, human-carried, and other/large-detection-volume equipment) encompassed six categories: personal radiation detector, extended-range personal radiation detector, personal emergency radiation detector, radioisotope identification device, human-portable detector/backpack, and vehicle-mounted large-detection-volume detector. Overall 19 models of equipment were included in the study. Laboratory evaluations were designed to assess the capabilities of the instruments in four consequence management missions: exposure rate, integrated exposure, radiation survey, and contamination screening. As applicable, the evaluations included measurement of exposure rate, integrated exposure, overrange response, and angular response. The results were compared to benchmarks from the American National Standards Institute N42.49A. The performance of the instruments for initial screening for contamination was assessed by an automated radioactive source moving past the detectors at various speeds and distances. The results demonstrate that if the equipment is used in accordance with the mission analysis and categories and within the original equipment manufacturer specifications, it is possible to achieve sufficient accuracy to estimate and document doses to responders, plan entries into contaminated areas, detect contamination, and protect the public until such time as outside resources arrive with sufficient numbers of standard health physics instruments and personnel dosimetry to replace the preventative radiological/nuclear detection instruments. This evaluation campaign was conducted to complement the National Council on Radiation Protection and Measurements Report 179, Guidance for Emergency Response Dosimetry.

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