A position sensitive ionization chamber for thermal neutrons

• Published in: 2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149) Vol. 1; pp. 5/163 - 5/166 vol.1
• Main Authors: Yu, B., Mahler, G.J., Schaknowski, N.A., Smith, G.C.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2000
• Subjects: Anodes; Backscatter; Helium; Ionization chambers; Neutrons; Noise shaping; Position sensitive particle detectors; Signal resolution; Spectroscopy; Strips
• ISBN: 9780780365032; 0780365038
• ISSN: 1082-3654; 2577-0829
• DOI: 10.1109/NSSMIC.2000.949106

A position-sensitive neutron detector based on /sup 3/He is being developed for a national Crystal Backscattering Spectrometer (CBS) at a pulsed neutron source. It comprises a single gas volume, of constant depth, in the form of an annulus that is also part of a truncated cone. Charge from each event is collected on one or two, anode strips, out of a total 336 around the annulus, yielding an angular resolution of about 1/spl deg/. Low noise signal processing, in the form of a monolithic preamplifier/shaping amplifier connected to each anode, provides electronic noise that is small enough to permit detector operation in ionization mode, and without the need for an electron-transmitting Frisch grid. This new detector therefore has significant advantages over previous detectors used in CBS instruments, which primarily consisted of arrays of individual /sup 3/He filled cylindrical counters with dead regions and nonuniform detection efficiency. The correct choice of gas mixture/pressure, drift field and shaping time is significant in achieving a successful performance in the new detector.