JPH0244283A - Radiation measuring apparatus - Google Patents

Abstract

PURPOSE:To enhance accuracy and to improve a frequency characteristic by mounting a radiation sensor outputting the current proportional to the energy of incident radiation and an element for detecting the magnetic field generated by the output current of said radiation sensor. CONSTITUTION:One terminal of a radiation sensor 1 is directly earthed and, in place of a conventional output resistor 3, an output element 4 measuring the magnetic field generated by the conductor connected to one terminal of the radiation sensor 1 and the earth is provided. A superconducting quantum interference device (SQUID)4 is formed by connecting both ends of a pair of semicircular members 4a, 4b composed of a superconductive material through Josephson junctions X, Y to form the same into a ring shape and connected to a bias circuit so that a bias current IC flows from the upper part R of the ring member 4a to the lower part S of the ring member 4b. Whereupon, the electron hole pair corresponding to the energy of radiation in the radiation sensor is generated and a magnetic field is generated around a circuit conductor by said hole pair. By this method, a fine magnetic field wherein a current flowing by radiation is generated can be measured with high accuracy by the detection element 4 having a radius of 5mm.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a radiation measuring device used in a medical radiation examination device.

As a radiation measuring device since the conventional technology μS, for example, Japanese Patent Application Laid-Open No. 1983-1
There is one shown in Japanese Patent No. 400885.

FIG. 3 shows a configuration for extracting the output from the radiation sensor of the radiation and line measurement stack disclosed in this publication, in which 1 is a radiation sensor, 2 is a power source, and 3 is an output resistor.

When radiation is incident on the radiation sensor 1, a number of electron-hole pairs are generated within the radiation sensor 1 according to the energy of the radiation. Since the radiation sensor 1 is biased by the power supply 2, a current proportional to the electron-hole pairs generated in the radiation sensor 1, that is, proportional to the energy of the incident radiation, flows in this circuit. This current causes a voltage drop across the resistor 3, and the voltage across the resistor 3 is taken out as an output voltage.

Problems to be Solved by the Invention In the above-mentioned conventional configuration, the output current of the radiation sensor is a weak current of several μm or less, and in order to obtain relatively stable changes in this weak current, the output resistance is set to a resistance value. Ω or more is required for 1. However, this circuit has parasitic capacitance of the radiation sensor 1 and stray capacitance of the signal line, and when the resistance value of the output resistor is increased, the time constant of the circuit becomes large and the frequency characteristics become very poor. Therefore, it is impossible to use an output resistor whose pressing value is too large, so there is a problem that a stable detection output with high accuracy cannot be obtained.

The present invention solves the above problems, and aims to provide a radiation measuring device that can measure radiation energy accurately and stably.

Means for Solving the Problems In order to achieve the above object, the radiation measuring device of the present invention has the following features:
A magnetic field detection element detects the magnetic field generated by the output current of the radiation sensor according to the energy of the incident radiation,
Radiation measurement output is obtained from the detection output of this magnetic field detection element.

Effect With the above configuration, the current flowing due to the radiation incident on the radiation sensor 1 is detected as a magnetic field and does not require a resistance to obtain an output. Therefore, the frequency characteristics due to the output resistance and the parasitic capacitance component in the circuit are No more deterioration,
It becomes possible to stably obtain a highly accurate detection output.

EXAMPLE Hereinafter, one implementation of the radiation apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of a radiation measuring device according to an embodiment of the present invention. Components in FIG. 1 that are similar to the conventional configuration shown in FIG. 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted. In FIG. 1, 1 is a radiation sensor that generates electron-hole pairs proportional to the energy of radiation when radiation is incident. 2 is a bias power source. In the configuration shown in FIG. 3, the output resistor 3 is inserted between one end of the radiation sensor 1 and the ground, but in this embodiment, one end of the radiation sensor 1 is directly grounded.

In place of the output resistor 3, an output element 4 is provided to measure the magnetic field generated by a conductor connecting one end of the radiation sensor 1 and the ground.

Figure 2 shows a superconducting quantum interference device (S) as a magnetic field detection element.
QUID: Superconductl
ng Quantum 1nterference D
evIce) is a plan view showing a schematic configuration of the evIce. This 5Q
In the UID 4, a pair of semicircular members 4 al 4 b made of a superconducting material are joined at both ends via Josephson junctions X and Y to form an annular shape.

A bias current ■ is applied from the upper part R of the ring member 4a to the lower part S of the ring member 4b. Connect to a bias circuit (not shown) so that the current flows. Electron-hole pairs are generated in the wire sensor according to the energy of the radiation, and current flows through the upper five paths including the sensor, and this current generates a magnetic field around the circuit and path conductors. For example, when the current flowing through the main circuit is 1 μA, the strength of this magnetic field is 1 μA from the circuit etc.
Approximately 8 x 10-mouth T at the Oram location. radius 5
The detection element 4 of II1m can measure with an accuracy of approximately 2.6×10 to LIT.

This accuracy can be adjusted by adjusting the radius of the element 4. Therefore, a minute magnetic field generated by a current flowing due to radiation can be measured by a magnetic field detection element through which an appropriate bias current Ic is flowing. Moreover, since one end of the radiation sensor 1 is directly grounded without passing through a resistor for output detection, a circuit with good frequency characteristics can be constructed.

Effects of the Invention According to the present invention, it is possible to construct a radiation measuring device with high accuracy and good frequency characteristics, although it has a simple configuration, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a radiation measuring device according to an embodiment of the present invention, FIG. 2 is a plan view showing the configuration of a magnetic field detection element, and FIG. 3 is a circuit diagram showing the configuration of a conventional radiation measuring device. It is. 1... Radiation sensor, 2... Power supply, 4... Magnetic field detection element. Name of agent: Patent attorney Shigetaka Awano Haka1/- Ho'F
7 bead death diagram

Claims (1)

[Claims] A radiation measuring device comprising: a radiation sensor that outputs a current proportional to the energy of incident radiation; and an element that detects a magnetic field generated by the output current of the radiation sensor.