PLATEAU SLOPES AND PULSE CHARACTERISTICS OF LARGE, HIGH-PRESSURE BF$sub 3$ COUNTERS

Technical Report · Wed Jul 01 04:00:00 EDT 1959

OSTI ID:4211618

Mendell, R B

Factors affecting the flatness of plateau of large diameter high- pressure BF/sub 3/ counters were examined. It was found that with gas and counter body free from contamination, counters up to 5 cm radius and filled with BF/sub 3/ gas at 64 cm Hg had acceptably flat plateaus. Desired gas purity was obtained by generating the gas from CaF/sub 2/BF/sub 3/ complex, trapping residual impurities, and isolating and collecting BF/sub 3/ vapor that had been in equilibrium with the liquid phase at a vapor pressure of 20 cm Hg. The resolution of counters of different pressures and cathode diameter for ionizing events with a known energy spectrum was compared. Specifically, the energies examined were those resulting from the reactions B/sup 10/(n, alpha )Li/sup 7/ and B/sup 10/(n, alpha )Li/sup 7/*. The effect of increasing pressure and counter diameter on measured pulse amplitude correlated with previous reports that electron attachment in BF/sub 3/ gas exists and increases with p/E. A rough estimate of capture cross section from the maximum of the pulse amplitude distributions in the various counters indicated a value of capture cross section smaller than that previously obtained. It was inferred that part of the capture cross section previously attributed to BF/sub 3/ may have resulted from electronegative impurities such as SiF/sub 4/ and SO/sub 2/. Pulse amplification characteristics of the different counters were determined, and results, including the effect of electron attachment on measured values for counters of large diameter and high pressure are discussed. (auth)

• Research Organization: New York Univ., New York. Coll. of Engineering
• NSA Number: NSA-14-003611
• OSTI ID: 4211618
• Report Number(s): AFOSR-TN-59-738
• Country of Publication: United States
• Language: English

Related Subjects

ALPHA PARTICLES
BERYLLIUM 10
BORON 10
BORON FLUORIDES
CALCIUM FLUORIDES
CATHODES
CONFIGURATION
CONTAMINATION
COUNTERS
CROSS SECTIONS
DIAGRAMS
DISTRIBUTION
EFFICIENCY
ENGINEERING AND EQUIPMENT
IMPURITIES
LITHIUM 7
NEUTRON BEAMS
NUCLEAR REACTIONS
OPERATION
PERFORMANCE
PRESSURE
PULSES
RESOLUTION
SILICON FLUORIDES
SULFUR OXIDES