Some studies on the development and applications of recoil particle track amplification by electrochemical etching for fast neutron dosimetry. Progress report. [For measuring neutron contamination in x-ray beams of medical accelerators]

Technical Report · Sat May 01 04:00:00 EDT 1976

OSTI ID:7176056

Sohrabi, M; Morgan, K Z

Further studies are reported on the development and application of fast-neutron-induced recoil particle track amplification in polycarbonate foils by electrochemical etching for fast neutron dosimetry. The performance of this dosimetry method for the measurement of fast neutron contamination in the high energy x-ray beams from three medical accelerators was investigated. Neutron dose equivalent ratios as well as their distributions in and out of the beam were determined. Neutron dose equivalent ratios of 0.66 and 1.27 percent were found in the beams of a 25 MeV Allis Chalmers and a 45 MeV Brown Boveri betatron, respectively. The fast neutron dose equivalent ratio in the beam of a Varian Clinac-18 were found to be zero due to insensitivity of this dosimetry approach to the soft neutron spectrum generated in this beam. The values for the two betatrons were in fair agreement with some values reported by other investigators. An electrochemical system was designed and constructed for large-scale neutron dosimetry. It is capable of etching 34 foils (each 2.5 cm in diameter) simultaneously. Improvements were made in the design of the chamber by using fixed stainless steel electrodes on the end walls of the chamber and reduced chamber length. These changes minimized the chamber volume and eliminated the effort of positioning and removing the electrodes each time the chambers are used. Background track densities in polycarbonate foils of different thicknesses obtained from different vendors are reported also. Masked foils gave the lowest and most reproducible background track densities (on the order of 0.8 +- 0.3 tracks/cm/sup 2/). Some further studies on the etching time and thickness dependence of this etching method are given also.

• Research Organization: Georgia Inst. of Tech., Atlanta (USA). School of Nuclear Engineering
• OSTI ID: 7176056
• Report Number(s): ORO-4814-9
• Country of Publication: United States
• Language: English

Related Subjects

440102* -- Radiation Instrumentation-- Radiation Dosemeters
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BARYONS
CARBON COMPOUNDS
CARBONATES
DIELECTRIC TRACK DETECTORS
DOSIMETRY
ELEMENTARY PARTICLES
ETCHING
FAST NEUTRONS
FERMIONS
HADRONS
MEASURING INSTRUMENTS
NEUTRON DOSIMETRY
NEUTRONS
NUCLEONS
OXYGEN COMPOUNDS
POLYCARBONATES
RADIATION DETECTORS
RECOILS
SURFACE FINISHING