NEUTRON DETECTORS

Journal Article · Thu Oct 01 00:00:00 EDT 1959 · Atompraxis (West Germany) Incorporated in Kerntechnik

OSTI ID:4222226

Rinn, F H

The predominant part played by neutrons in nuclear physics and technology requires devices for measuring both intensity and energy distribuiion. Since neutrons cannot ionize, they are demonstrable only via nuclear reactions producing charged particles. Detectors for demonstrating thermal neutrons utilize the large effective cross-section of the isotopes B/sup 10/ and Li/sup 6/ for the (n, alpha ) reaction. Tubes filled with BF/sub 3/ are used as counters, since these are proportional counters, they provide good discrimination against gamma - quanta. For higher neutron fluxes. neutron chambers with boron-coated electrodes are used. A careful choice of chamber materials keeps self-activity and the resultant falsification of the measurement result at a low level. An extension of the measurement range to lower neutron fluxes is possible by using compensated neutron chambers which eliminate the chamber current from gamma radiation. Thermocolumns have proved useful for measuring high neutron fluxes. Neutron scintillationcounters have certain advantages over BF/sub 3/ counters: the alpha -particles from (n, alpha ) reactions as well as the gamma , quanta from (n, alpha ) reactions can be used for neutron demonstration. Fast neutrons can also be detected with these detectors if they have previouslly been decelerated to thermal velocity by suitable moderators. Counter tubes and scintillation counters are suitable for messuring intensity and energy if the fast neutrons are allowed to produce ionizing recoil nucleii by elastic collision. Here the problem of gamma discrimination is rather difficult, but a marked reduction of gamma sensitivity can be attained by registering anticoincidences and delayed coincidences, or by utilizing the different scintil;ation-time constants for different exciting particles. Nuclear reactions with a reaction threshold value are also suitable for neutron measurement. There are no good measurement methods for neutrons in the moderately fast range; thus at present they are undetectable. (auth)

• Research Organization: Siemens and Halske A.G., Karlsruhe, Ger.
• NSA Number: NSA-14-003665
• OSTI ID: 4222226
• Journal Information: Atompraxis (West Germany) Incorporated in Kerntechnik, Journal Name: Atompraxis (West Germany) Incorporated in Kerntechnik Vol. Vol: 5; ISSN ATPXA
• Country of Publication: Country unknown/Code not available
• Language: German

Related Subjects

ALPHA PARTICLES-- BERYLLIUM 10-- BORON FLUORIDES-- CHARGED PARTICLES-- COUNTERS-- CROSS SECTIONS-- DISTRIBUTION-- EFFICIENCY-- ENERGY-- GAMMA RADIATION-- IONIZATION-- LITHIUM 6-- MEASURED VALUES-- NEUTRON BEAMS-- NEUTRON DETECTION-- NEUTRONS-- NUCLEAR REACTIONS-- RADIATION DETECTORS-- THERMAL NEUTRONS
ALPHA PARTICLES-- BORON FLUORIDES-- COINCIDENCE METHODS-- COUNTERS-- ENERGY-- FAST NEUTRONS-- GAMMA RADIATION-- INTERACTIONS-- MEASURED VALUES-- MODERATORS-- NEUTRON BEAMS-- NEUTRON DETECTION-- NUCLEAR REACTIONS-- RECOILS-- SCINTILLATION COUNTERS-- SENSITIVITY-- THERMAL NEUTRONS-- THRESHOLD ENERGY
BORON-- COATING-- ELECTRODES-- ERRORS-- GAMMA
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