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CALIBRATION OF THE T(D,N) HE-4 YIELD FROM THE NUCLEAR DEFENSE LABORATORY'S POSITIVE ION ACCELERATOR
ARMY NUCLEAR EFFECTS LAB EDGEWOOD ARSENAL MD
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The Cockcroft-Walton Positive Ion Accelerator, with a maximum energy of 780 kev, is capable of producing neutron or gamma reactions, or of providing a direct beam of approximately one milliampere of low Z nuclei. The Td,nHe-4 reaction which produces 14-mev neutrons and 3.5-mev alpha particles is treated. Two methods were used to measure the neutron flux at a given point. The first method employed the use f a flux measuring device known as a long counter. The second method calculated the neutron flux at a given point from a knowledge of the total neutron production, their angular distribution, and the distance to the point of interest. This latter technique consisted of determining the D-T yield by the associated alpha method. It was concluded that the long counter is most useful as a monitor of neutron production. Its use as an absolute flux measurement device required the determination of efficiency at the given energy and background neutron count rate, Io. The first requirement is difficult and the second is a nuisance. When neutrons are produced from a reaction that does not involve a readily counted associated particle, it will be useful to have the long counter calibrated for flux measurements. The alpha particles may be counted with high accuracy. The flux, however, must be calculated, and such a calculation involves assumptions. The errors involved become more important as deuteron energy increases. Author
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