Accession Number : AD0770112


Title :   Charge Collection Characteristics of an Air Ion Chamber for 0.2-microsec Pulses of 25 MeV Electrons


Descriptive Note : Technical note


Corporate Author : ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD


Personal Author(s) : Kiker, W E


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD= AD0770112


Report Date : Aug 1973


Pagination or Media Count : 21


Abstract : The charge collection characteristics of a parallel-plate transmission air ion chamber have been measured for 0.2-microsec pulses of 25 MeV electrons over a range of initial charge densities from 0.6 to 430 esu/cc. Plate spacings of 0.07, 0.40 and 0.73 cm were used with E/p values of 1 and 6; 1, 3 and 6; and 1 and 3 V/cm mm Hg, respectively. Electron beam monitoring was done with a graphite Faraday cup. The results of the experiment were compared with calculated values of charge collection efficiency from a model that accounts for negative ion collection by means of Boag's theory and electronic charge collection by an empirical model. The relative proportion of negative ions to electron charge carriers was calculated from a theory due to Thomson and to Boag and Wilson. Charge collection efficiency as calculated from the model was in good agreement with experimental values.


Descriptors :   *ELECTRON BEAMS , *IONIZATION CHAMBERS , COMPUTATIONS , EFFICIENCY , LINEAR ACCELERATORS , MONITORS , SPACE CHARGE


Subject Categories : Nuclear Instrumentation
      Particle Accelerators


Distribution Statement : APPROVED FOR PUBLIC RELEASE