A NEUTRON MONITOR FOR ENERGIES ABOVE 20 MeV

Technical Report · Fri Aug 01 04:00:00 EDT 1958

OSTI ID:4299281

Holt, P D; Clare, A B

Details are presented of the carbon-11 scintillation threshold detector of neutrons, with a summary of the preseat performance. A polystyrene phosphor is irradiated in the neutron flux and carbon-11 is produced by the C/sup 12/ (n,2n)C/sup 11/ reaction; the phosphor is then removed and the positron activity of the carbon-11 observed with a photomultiplier. The main problems are reduction of the background for the carbon-11 counting, determination of the carbon-11 counting efficiency and assessment of the statistical accuracy of the result. The threshold energy is 20.4 Mev; assuming that the maximum permissible flux of neutrons of energy greater than this is independent of the energy, then the carbon-11 activity will be approximately proportional to the tissue dose, up to at least 400 Mev. A flux of 1O neutrons/cm/sup 2//sec (half the maximum perzmissible flux) may be measured with a statistical standard deviation of 10%, the total time required (including that for the background count) being 2 hours. (auth)

• Research Organization: United Kingdom Atomic Energy Authority. Research Group. Atomic Energy Research Establishment, Harwell, Berks, England
• NSA Number: NSA-13-001281
• OSTI ID: 4299281
• Report Number(s): AERE-HP/R-2644
• Country of Publication: United Kingdom
• Language: English

Related Subjects

ACTIVATION
BACKGROUND
CARBON 11
CARBON 12
DECAY
EFFICIENCY
ENERGY
ENERGY RANGE
ERRORS
FAST NEUTRONS
INSTRUMENTS
IRRADIATION
MEV RANGE
MONITORING
NEUTRON DETECTION
NEUTRON FLUX
NUCLEAR REACTIONS
PERFORMANCE
PHOSPHORS
PHOTOMULTIPLIERS
PLANNING
POLYSTYRENE
POSITRONS
QUANTITATIVE ANALYSIS
RADIATION DETECTORS
RADIATION DOSES
RADIOACTIVITY
SCINTILLATION COUNTERS
STATISTICS
THRESHOLD DETECTORS
TISSUES
VARIATIONS