Fabrication of a Set of Realistic Torso Phantoms for Calibration of Transuranic Nuclide Lung Counting Facilities

A set of 16 tissue equivalent torso phantoms has been fabricated for use by major laboratories involved in counting transuranic nuclides in the lung. These phantoms, which have bone equivalent plastic rib cages, duplicate the performance of the DOE Realistic Phantom set. The new phantoms (and their successors) provide the user laboratories with a highly realistic calibration tool. Moreover, use of these phantoms will allow participating laboratories to intercompare calibration information, both on formal and informal bases. 3 refs., 2 figs

Tissue-Equivalent Torso Phantom for Calibration of Transuranic-Nuclide Counting Facilities

Several tissue-equivalent human-torso phantoms have been constructed for the calibration of counting systems used for in-vivo measurement of transuranic radionuclides. The phantoms contain a simulated human rib cage (in some cases, real bone) and removable model organs, and they include tissue-equivalent chest plates that can be placed over the torso to simulate people with a wide range of statures. The organs included are the lungs, liver, and tracheobronchial lymph nodes. Polyurethane with varying concentrations of added calcium was used to simulate the linear photon-attenuation properties of various human tissues, including lean muscle, adipose-muscle mixtures, cartilage, and bone. Foamed polyurethane was used to simulate lung tissue. Organs have been loaded with highly pure /sup 238/Pu, /sup 239/Pu, /sup 241/Am, and other radionuclides of interest. The validity of the phantom as a calibration standard has been checked in separate intercomparison studies using human subjects whose lungs contained a plutonium simulant. The resulting phantom calibration factors generally compared to within +-20% of the average calibration factors obtained for the human subjects

Lawrence Livermore Laboratory AMBIENT ENVIRONMENTAL RADIATION MONITORING AT THE LAWRENCE LIVERMORE LABORATORY EWIFONMEOTAL RADIATION KWITORMG AT THE LAWREUCE LTVEFWJEE LABORATORY*

Abstract Thermoluminescence dosimetry Is the principal means of measuring ambient ganira radiation at the Lawrence Livermare laboratory. These dosimeters are used at 12 perimeter locations and 41 locations in t;ie off-site vicinity of the Laboratory, and are exchanged quarterly. Cc.trol doslTeters are stored i/i a 75-mm-thick lead shield located out-of-doors to delicate tenperature cycling of field dostiteters. Effect of dosimeter response to radiation in the shield is determined each quarter. Calibration lrradiatior.s are made midway through the exposure cycle to compensate for signal fading. TerrestrL-.l exposure rates calcu lated from the activities of naturally occurring uranium, thorium, and potassium in Uvernore ,J alley soils vary from 3 to 7 pR/hr. Local Inferred exposure rates from cosMc radiation are approximately 4 uR/hr. TLD measurements are in good agreement with these data. Off-site and site perimeter data are conparad, and differences related to Laboratory operations are discussed

Balance of Mass, Momentum, and Energy in Splintering Central Collisions for 40Ar up to 115 MeV/Nucleon

For central collisions of (17–115)AMeV 40Ar+Cu, Ag, Au, an overall balance is determined for the average mass, energy, and longitudinal momentum. Light charged particles and fragments are separated into forward-focused and isotropic components in the frame of the heaviest fragment. Energy removal by the isotropic component reaches 1–2 GeV. For such high deposition energies, statistical multifragmentation models predict much more extensive nuclear disassembly than is observed

Isotropic Emission Components in Splintering Central Collisions (17-115)A MeV 40Ar+Cu, Ag, Au

Matière Nucléair