CS237644B1 - Gamma radiation dose rate detector - Google Patents

Abstract

The detector consists of 2 to 100 P N junctions, arranged one after the other, preferably in a sandwich arrangement, with recombination centers introduced into the volume of the semiconductor. The invention is intended for all workplaces using gamma radiation.

Description

BACKGROUND OF THE INVENTION The present invention relates to a gamma dose rate detector having increased sensitivity and detecting either photocurrent or photovoltaic.

The state of the art in the field of accurate and continuous targeting of gamma radiation for the purposes of experiments conducted in intense neutron-gamma mixed fields can be characterized as less satisfactory. Ionization chambers commonly used in reactor technology for these purposes are generally not suitable. In the ranges of exposure rates and doses occurring in these fields, methods using individually designed calorimeters based on the measurement of the heating of absorbent bodies of different materials predominate. Among the activation methods, the possibilities of using platinum or lead-free soldering detectors were rarely investigated. The method of calorisation of special types of glass has very limited applicability. Standardly produced sensors for experimental purposes are not produced at all.

The exact applications of semiconductor materials for the purposes of the above mentioned experiments in intensive neutron and gamma mixed fields are also unknown, only some of the laboratory or pilot plant measurements are performed under completely different conditions. However, the response pattern in these cases is not usually satisfactory and requires a number of supplementary calibration measurements in particular. Detector sensitivity determination is mostly related to a number of difficult to determine conditions, such as energy spectrum of the source, arrangement geometry and the like.

According to the invention, these are eliminated by a gamma radiation dose rate detector consisting of 2 to 100 P ⁺ N transitions arranged in series, preferably in a sandwich arrangement, with recombination centers introduced into the semiconductor volume.

The basic effect of the detector of the present invention lies in the ease of dose rate evaluation. Semiconductor sensors of this structure can be easily manufactured, which is associated with their low cost. The sensitivity can be controlled by the volume of the detector. Neutron radiation resistance increases the introduction of platinum atoms into the semiconductor volume. A wide range of measured dose rates is possible, ranging from 6.45 · 10 "$ to 2.58.10" ^ c kg s ^- '.

The invention is described in more detail below with reference to a specific embodiment in which conductive regions of type P ⁺ and N ⁺ of depth were formed in silicon wafers of conductivity type N / resistivity of 0.2 µm / o thickness of 200 µm by diffusion operations / diffusion B and P /. 30 / im. After these operations, recombination centers were introduced into the silicon wafers by Pt diffusion. After chemical cleaning of the Si plates, the required number of plates (25pcs) was fused together with aluminum foils to form a cylinder of fl plates. Individual 10 x 10 mm and 16 x 16 mm sandwich detectors were cut from the lead-coated cylinder and subjected to chemical treatment to stabilize the surface. After these modifications, the sandwich detectors were equipped with leads on the front surfaces and light-tight encapsulated. System sensitivity of the surface of 10 x 10 mm ² ^ MVC agent 812,2.10 kg ^{-1 _1,} of an area of 16 × 16 mm ² was 1 550.4 x 0 ⁴ mVC'kg with ^{the first}

The detector was connected to the input of the MAC 156 amplifier, which operated in I / U mode with a 1 zpět feedback resistor. The results are shown in the table below:

Emitter Co 60 Dose rate (R / hour)

0.1 0.5 1.0 5.0 10.0 50.0 '

Amplifier Output Voltage / mV /

-2.1

-12.65

-22.76

-123.1

-2 (64.75

-1 281.8

100 ALIGN!

200

-2 506.8 -4 941.8

The energy dependence is similar to all semiconductor detectors made

2 on silicon. The radiation resistance is 10 neutrons / om for the input of thermal and fast neutrons. with no decrease of response to 30% approx. 200 hours. The noise itself is in the order of tens of pV, which is negligible for the signal in mV units.

The sandwich detector can be used in all workplaces using gamma rays, eg energy in experimental work in medicine, agriculture, geology and the like.

Claims (1)

OF THE INVENTION A gamma radiation dose rate detector characterized in that it consists of 2 to 100 P ⁺ N transitions arranged in series, for example in a sandwich arrangement, wherein recombination centers are introduced into the volume of the semiconductor.