The Sensitivity of AgBr Crystals in Ionographic Emulsions (thesis); SUR LA SENSIBILITE DES CRISTAUX DE AgBr DANS LES EMULSIONS IONOGRAPHIQUES (theses)

Technical Report · Fri Jan 01 04:00:00 EST 1960

OSTI ID:4016690

Gentil, M -C.L.-Le

The Gurney-Mott theory and the Mitchell theory on the formation of the latent image and the effect of photographic sensitizers were reviewed. in conformance with the Gurney-Mott theory the granulation of a particle track was determined, using the Berriman theory but introducing the effect of fluctuation on the specific loss of energy. A preliminary evaluation was made of the number of positive holes produced in order to obthin an order of magnitude. The loss of energy of the incident particle was determined first in the different constituents of the emulsion and then in the electrons of the different layers of the two atoms of AgBr. The quantum theory and classical theory were used to determine the energy of the electrons emitted during the interactions of the incident particle with the crystal. The results obtained by the two methods were compared and extended to hydrogenoid atoms. The sensitivity of crystals was defined. The case of the track produced by an incident proton crossing the Br/ sup -/ and Ag/sup +/ ions of a G5 emulsion was studied. The energy distribuion of all the electrons ionized along the trajectory of the cident panticle was calculated. The sensitivity of the AgBr crystal of the G5 emulsion was studied first at the ionization minimum and then at variable energies. The the correerimental ed in conclusion. (J.S.R.) O H20337 Design features of a whole- body counter are described. The counter employs two 8- x 4-in. NaI crystals inside a steel room, a scanning system to utilize the increased sensitivity of the large crystals, and collimators with a 5-in. focal distance. The system allows the estimation of radioactivity in vivo independent of its distribution within the human body by the use of geometrical and gamma -absorption corrections. Iodine-131 scans, comparable to those obtained with a smaller moving crystal, were obtained by one crystal placed inside a 3-in.-thick Pb shield with a focusing head at the side of the crystal face. The advantages of using the larger crystals include increased focal distance, higher sensitivity, and adaptability to high energy gamma emitters. (C.H.)

• Research Organization: Paris. Universite
• NSA Number: NSA-18-020336
• OSTI ID: 4016690
• Report Number(s): NP-13851
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ATOMIC MODELS
CRYSTALS
ELECTRONS
EMISSION
ENERGY
GRAIN SIZE
IMAGES
INSTRUMENTATION
INTERACTIONS
IONIZATION
LOSSES
NUCLEAR EMULSIONS
ORBITS
PARTICLE TRACKS
PARTICLES
QUANTUM MECHANICS
SENSITIVITY
SILVER BROMIDES