[en] In this paper we give the main characteristics of a great dynamic fission chamber (11 decades)

[en] This invention refers to a detector of particles that enables accurate determinations to be effected at high temperature, irrespective of the particle flux to which it is subjected (for example, a neutron flux in the core of a reactor) and preferentially is of elongated shape and particularly reduced radial section. According to the invention, the specifications of this detector include a body in a single piece, made of a ceramic material, in which are embedded and sealed two concentric tubular electrodes forming between them an annular chamber filled with a gas under pressure and electric wires connecting the electrodes to the outside of the body

[en] Multiplate fission chambers were used in experiments at TRIUMF to measure the absolute muon induced fission yield. To determine the yield, the fission chamber detection efficiencies must be known. In this paper, the methods of efficiency calibration have been discussed. (author)

[en] Published in summary form only

[en] The neutron detector consists of a fission chamber and a compensated ionisation chamber for neutron flux between 1 and 10¹⁰/cm²/sec. The maximum flux for neutron detectors in impulse counting operation is limited by the saturation and the minimum which is detectable due to DCα signal noise. The detector contains a small quantity of UO₂ which is deposited on an electrode. Part of the detector is in the form of a compensation chamber. It contains Ra²²⁶. The α signal noise is suppressed by the reduction of the U 234 content in UO₂ to less than 100 ppm. The γ compensation signal can be produced by an external circuit. (DG) 891 HP

[en] A prototype fission chamber has been extensively tested and several chambers assembled in preparation for the Fast Flux Test Facility - Reactor Characterization Program (FFTF - RCP). The major portion of our report concerns the chamber design and performance characteristics. The absolute efficiency of the device will not be explicitly discussed. In ruggedizing the chamber, great care has been taken not to significantly alter the absolute efficiency as compared to the more conventional NBS configuration. This configuration and the measurement of absolute fission rates have already been rigorously discussed in an earlier report. The FFTF characterization effort will be reported in a future paper after the measurements have been completed

[en] The main causes of residual activation currents in dc mean current ionisation chambers are briefly discussed. Theoretical and experimental aspects of fission product and wall activation effects are considered and performance data for a typical chamber derived. The likely ways in which this performance can be changed by modifications to the design are stated. (author)

No abstract available

No abstract available

[en] The signals of fission chambers are usually evaluated with the help of the co-called Campbelling techniques. These are based on the Campbell theorem, which states that if the primary incoming events, generating the detector pulses, are independent, then relationships exist between the moments of various orders of the signal in the current mode. This gives the possibility to determine the mean value of the intensity of the detection events, which is proportional to the static flux, from the higher moments of the detector current, which has certain advantages. However, the main application area of fission chambers is measurements in power reactors where, as is well known, the individual detection events are not independent, due to the branching character of the neutron chains (neutron multiplication). Therefore it is of interest to extend the Campbelling-type theory for the case of correlated neutron events. Such a theory could address two questions: partly, to investigate the bias when the traditional Campbell techniques are used for correlated incoming events; and partly, to see whether the correlation properties of the detection events, which carry information on the multiplying medium, could be extracted from the measurements. This paper is devoted to the investigation of these questions. The results show that there is a potential possibility to extract the same information from fission chamber signals in the current mode as with the Rossi- or Feynman-alpha methods, or from coincidence and multiplicity measurements, which so far have required detectors working in the pulse mode. It is also shown that application of the standard Campbelling techniques to neutron detection in multiplying systems does not lead to an error for estimating the stationary flux as long as the detector is calibrated in in situ measurements