FR2553897A1 - LARGE SURFACE PROPORTIONAL METER FOR DETECTION OF ALPHA AND BETA RADIATION - Google Patents

Abstract

A. LARGE-SURFACE PROPORTIONAL COUNTER. B. CHARACTERIZED IN THAT, AT CHAMBER 9 WITH NITROGEN METERING GAS, A GAS REGENERATION DEVICE 2-4 IS CONNECTED AND THAT METERING GAS IS LIKELY TO PASS THROUGH THE GAS REGENERATION DEVICE 2-4 . C. THE INVENTION RELATES TO LARGE-SURFACE PROPORTIONAL COUNTERS.

Description

1. Large area proportional counter for the detection of

  alpha and beta radiation "The invention relates to a proportional counter with a large area of reduced eigenvactivity for detecting alpha and beta radiation or gamma with

counting gas.

  Conventional large area meters can be operated either by gas circulation or as

  Waterproof meters with gas filling The disadvantage of the gas flow meter is its dependence on a permanent and in many cases expensive gas supply.

  In the case of a leak-tight meter with gas filling, the leakage rates and the chemical dematerialization determine its lifetime. The multiplication by gas of a feedstock highly depends on the purity of the metering gas. low leakage rates and therefore a long life, a meter with a fixed fill requires windows so thick that the alpha radiation does not

can it be measured?

  C The problem underlying the invention consists in obtaining a complete incompetence of the gas stored for

  a large area counter of the type initially mentioned.

  From the point of view of distortion, air is the ideal feed gas. Natural ambient air is, however, not usable as a counting gas. The adverse electrochemical properties of oxygen preclude the use of concentration. Oxygen at the oxygen content of the air Mixtures of nitrogen and oxygen with O 2 concentrations of up to 2%, however, are suitable as proportional gas. The gas amplification remains constant until this time. concentration and is identical to that of pure nitrogen. The solution of this problem is that, in the chamber with the nitrogen counting gas, a gas regeneration device is connected and that the counting gas is able to pass through the regeneration device. Other features allow advantageous embodiments of the invention to be considered, characterized in that the gas regeneration device comprises a molecular sieve and an absorber which removes oxygen from the metering gas and in that the counting gas which connects the volume of the chamber with the molecular sieve

  and the absorber is arranged a fan or a pump.

  The invention therefore provides for the use of nitrogen as a counting gas in a sealed meter. The gas purification device connected with a gas circulation guarantees for long periods the same concentration.

  counting gas and therefore a long life of the detector.

  Because of the low nitrogen gas amplification, electronics with the most favorable signal-to-noise ratio are required. As a result, the preamplifiers which are sensitive to

  load and detectors of low capacity, low noise.

  The invention will be explained below with reference to an exemplary embodiment shown in the accompanying single figure.

  A regeneration device 2, having the shape

  of a cartridge, is coupled on the bottom of a proport $ onal counter large area 1 (the figure schematically shows the installation).

  3. In the cartridge, between two frontal molecular sieves carried by front grids 3, there is an O 2 absorber. The cartridge can be screwed into a block 6 which has in a recess a fan 7, which is disposed below. 3 of this recess in the block 6, a pipe 8 leads to the chamber 9 of the large area proportional counter 1, so that

  circulation by pumping the metering gas is possible.

  The gas purification cartridge 24 removes oxygen and moisture from the air. The impurities penetrating from the outside, essentially O 2 and moisture, are thus eliminated. The diffusion-penetrating nitrogen is, on the other hand,

  desired in the sense of a renewal of the gas.

  The solution of the concept resides in the following components: 1. Conventional large area gas-tight meter with reduced clean capacitance, high amplification,

  235 r V / 106 ion pairs, the amplification factor 550.

  2. 3 A or 4 A oclecular gas purification cartridge for the elinination of water vapor, for example a catalyst R 3-11 (BASF), reduced, for the adsorptide of the oxygen,

  3. gas flow: Sealed pump S, fan built into the gas purifier cartridge or temperature drops.

4.

RE VE N D I C A T IO N S

  1. Large area proportional counter for the detection of alpha and beta radiation or gamma radiation with a metering gas and with a very reduced capacitance, characterized in that, in the chamber (9) with the gas of nitrogen count, a gas regeneration device (24) is connected and the counting gas is able to pass through the regeneration device

of gas (2 4).

  2 proportional large area counter according to claim 1, characterized in that the gas regeneration device (2 4) comprises a molecular sieve (4)

  and an O 2 absorber (5) which removes oxygen from the counting gas.

  3 Large proportional counter according to

  any of claims 1 and 2, characterized in that

  in a metering gas circuit which connects the volume (9) of the chamber with the molecular sieve (4) and the absorber (5), a fan (7) or a pump is arranged. 20