SENSITIVE PERSONNEL DOSIMETRY OF 3KEV TO 20MEV NEUTRONS

A FAST NEUTRON DOSIMETER IS PLANNED THAT WOULD BE USED BY PERSONNEL INVOLVED IN RESEARCH OR MEDICAL TREATMENT WITH NEUTRONS, AND WOULD THUS SATISFY SOME OF THE NEEDS OF THE NATIONAL CANCER INSTITUTE (NCI). THE DOSIMETER WILL BE SENSITIVE TO NEUTRONS OF >3-KEV ENERGY WITH NEGLIGIBLE RESPONSE TO OTHER RADIATION. THE NOVEL SYSTEM USES RESONANCE IONIZATION SPECTROSCOPY (RIS) TO COUNT NOBLE GAS ATOMS SPUTTERED FROM A SOLID MATRIXMATERIAL BY COLLISION EVENTS THAT CORRELATE WITH NEUTRON DOSE. THE SOLID MATRIX MATERIAL AND THE NOBLE GAS ATOMS RELEASED FROM IT WOULD BE CONTAINED IN THE "NEUTRON BADGE"; THE NOBLE GAS ATOMS RELEASED DURING THE EXPOSURE PERIOD WOULD THEN BE COUNTED IN A LABORATORY "READER" USING RIS. THE ULTRAHIGH SENSITIVITY AND SELECTIVITY OF RIS ALLOW RELIABLE DETERMINATION OF THE SMALL NUMBER OF ATOMS RELEASED. CALCULATIONS INDICATE SENSITIVITY BELOW 1 MREM, AND NCRP 39 REM RESPONSE CONSTANT WITHIN A FACTOR OF TWO TO NEUTRONS FROM 3 KEV TO 20 MEV. PHASE I WILL INVESTIGATE FEASIBILITY BY EXPERIMENTALLY VERIFYING THAT NOBLE GAS ATOMS ARE RELEASED FROM THE SOLID MATRIX BY NEUTRON IRRADIATION AND THAT THE SPONTANEOUS RELEASE OF NOBLE GAS ATOMS FROM THE MATRIX CAN BE REDUCED TO ACCEPTABLE LEVELS. PHASE II WILL REQUIRE SENSITIVITY ANDENERGY RESPONSE MEASUREMENTS, DEVELOPMENT OF LOW-BACKGROUND PACKAGING AND PRACTICAL READERS, AND FIELD TESTS OF PROTOTYPE UNITS IN MIXED RADIATION ENVIRONMENTS.