A directional gas Cherenkov counter, which employed six phototubes to sample Cherenkov light from single particles having a gamma greater than ~10 was used to achieve accidental rates of less than one per day if operated near targets with surface radiation levels of as high as 10/sup +3/ r/hr. The cosmic ray background measured by the apparatus was reduced to less than one per day by mounting our directional Cherenkov counter above the irradiated targets and facing toward the earth. Two searches of a few days duration, after bombardments at energies of 300 and 400 GeV with >10/sup 16/ protons at NAL, were made in four inch thick targets of aluminum, mounted just down stream from another aluminum target. No long-lived particles were observed with cross sections for production and capture of approximately less than a micro-micro barn in a lifetime range of a few to a few thousand hours. (auth) from the decay of a long-lived intermediate state. (auth)

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From eighteenth Health Physics Society meeting; Miami Beach, Florida, USA (17 Jun 1973). A refresher course to provide a practical approach to the use of statistical concepts in interpreting data related to problems of applied health physics is given. After a brief review of the theoretical probability distributions, emphasis is placed on counting statistics, in particular the concept of the standard deviation. In this category the following topics are covered: (1) calculation of the standard deviation, (2) propagation of errors (when two or more quantities are combined arithmetically or via a formula), (3) confidence limits, and (4) the null hypothesis. The following topics are also discussed. (1) Chi-Square in relation to checking the reliability of a counting instrument, (2) correction factors for deadtime losses, and (3) for the case of a decaying source. (auth)