A SLOW AND FAST NEUTRON SCINTILLATION COUNT-RATE AND DOSE-RATE METER

摘要

A compact, scintillation, transistorized slow and fast neutron count-rate and dose-rate portable instrument was developed. The basic instrument weighs approximately six pounds without moderator. A spherical 10-inch diameter paraffin moderator weighing 15 pounds is used with the instrument for fast neutron dose-rate determinations. A spherical polyethylene, 10-inch diameter moderator may also be used. The polyethylene moderator weighs 10 pounds.nThe thermal and slow neutron sensitivity is approximately 100 c/m/n/ cm /sec of the first range full scale sensitivity is approximately 0.1 mrem/hr for thermal neutrons.nUsed with the 10-inch moderator, the instrument has an approximate dose-rate sensitivity of 10, 000 c/m millirad/hour. For fast neutrons the instrument is energy independent to - 20 per cent from 0. 3 Mev to 2. 5 Mev. This curve approached the curve of the double-moderator and BF„ tube of Dr. De Pangher.nThe three ranges employed are: 0-1000, 0-10,000 and 0-100,000 c/m with the first range corresponding to 0.1 mrem/hr for thermal and slow neutrons and to 0.1 mrad/hr for fast neutrons. The range sensitivities can be decreased by merely masking part of the crystal detector light-output window or by using a smaller crystal. The battery life is 110 hours with continuous operation. The, instrument is not affected by radium gamma fields of less than three r/hr.