JPS60159675A - Radiation detector - Google Patents

Abstract

PURPOSE:To improve space resolving power and linearity by arranging plural pieces of optical fiber-like scintillators each formed by coating the circumference of a transparent scintillator with a clad layer having a high refractive index in parallel and detecting the light emitted from each end. CONSTITUTION:A transparent plastic scintillator is used as a core material 31 and the circumference there of is coated with a clad layer 32 consisting of a material having the refractive index higher than the refractive index of the core material 31 into a fiber shape, by which an optical fiber-like scintillator 1 is formed. The plural fiber-like scintillators 1-16 formed in such a way are arranged in parallel. Each of the scintillators 1-16 emits light from both ends and therefore if the ends of the respective fiber-like scintillators are conducted to eight pieces of photor multipliers A-H, the fiber-like scintillators which emit light can be identified. The one-dimensional light emitting place with respect to the arraying direction of the fiber-like scintillators, i.e., the incident position of charge particles is thus known.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a radiation detector used in an autoradiographic camera or the like, and particularly to a radiation detector suitable for detecting the position of charged particles.

(B) Prior Art Conventionally, spark chambers and the like have been used to detect the positions of charged particles, but there have been problems in that high spatial resolution cannot be obtained and there are many cases of missing counts at a high 41 number rate.

(C) Objective The object of the present invention is to provide a radiation detector that has high spatial resolution, excellent linearity of detection positions, and has fewer missed counts even at a high counting rate.

(D) Structure The radiation detector according to the present invention uses an optical fiber-like scintillator that has a transparent scintillator as a core material and is coated with a cladding layer made of a material having a higher refractive index than the core material to form a fiber. A plurality of scintillators are arranged in parallel, and the light emitted from the end of each fiber-shaped scintillator is detected by a photodetector.

(E) Embodiment In FIG. 1, a transparent plastic scintillator is used as the core material 31, and its periphery is covered with a cladding layer 32 made of a material with a higher refractive index than the core material 31 to form a fiber shape. An optical fiber scintillator 1 is formed. This cladding layer 32 may be made of glass, plastic, or the same plastic scintillator as the core material 31 as long as it satisfies the refractive index conditions. In this fiber-shaped scintillator l, when a charged particle passes through this fiber-shaped scintillator l as shown by the trajectory 33,
The core material 31 emits light along a locus 33, and the light is transmitted in the longitudinal direction while being totally reflected at the interface with the cladding layer 32, and is emitted from both ends.

A one-dimensional position detector can be constructed by arranging a large number of fiber-shaped scintillators 1-16 (16 in this embodiment) in parallel as shown in FIG. 2. Each of the fiber-shaped scintillators 1 to 16 emits light from both ends, so if the ends of each fiber-shaped scintillator are guided to eight photomultiplier tubes A to H in the combination shown in FIG. It can be seen whether the fiber-shaped scintillator emitted light. That is, for example, if light emission is detected simultaneously by photomultiplier tube A and photomultiplier tube E, it can be seen that light emission has occurred in fiber-shaped scintillator l. Therefore, the simultaneous detection of 164v4 is sufficient to enable simultaneous detection of 16 combinations when one Yamariki is taken out from each group of photomultiplier tubes A-D and photomultiplier tubes E-H and combined. By providing a counting circuit, it is possible to know the one-dimensional light emitting location, that is, the incident position of the charged particles in the arrangement direction of the phi/<-shaped scintillators.

Furthermore, a two-dimensional position detector can be constructed by using two sets of such one-dimensional position detectors so that their detection directions do not overlap. That is, as shown in FIG. 3, 10 fiber-shaped scintillators 1-10 are arranged in parallel to form a first layer, and this is layered with other lO-tree fiber-shaped scintillators 1-10.
-20 are stacked on top of the second layer formed by arranging them in parallel so that the directions of the two are substantially perpendicular. Then, the charged particles penetrate these two layers as shown in trajectory 33, so one-dimensional position detection in each layer can be performed as in Section 2.
A two-dimensional position can be detected by both. In this case, it is also possible to stack three or more layers. Further, by arranging two sets of two-layer two-dimensional position detectors so as to overlap each other with a space in between, it is possible to know the flight trajectory (position and direction) of charged particles passing through them. - Here, charged particles include electrons, positrons, gamma rays, proton beams, etc., and these can be detected. Moreover, neutral r-rays can be detected by providing a converter for converting neutrons into charged particles on the incident side surface of these position detectors.

Fiber-shaped scintillators can be manufactured in various thicknesses from lOILm to about 1 mm, and high-resolution position detection can be performed by arranging a large number of thin fiber-shaped scintillators.

Furthermore, the linearity of the detection position is determined by the accuracy of arranging the fiber-shaped scintillators (accuracy of pitch), and by arranging them with high precision, extremely excellent linearity can be easily achieved.

Note that although the light emitted from the end of the fiber-shaped scintillator is detected by a photomultiplier tube in the above example, the present invention is not limited to this, and other photodetectors may be used. Furthermore, the number of fiber-shaped scintillators is not limited, and it goes without saying that the cords used when combined as shown in FIG. 2 are not limited to those shown in this figure.

(f) Effects According to the radiation detector of the present invention, the spatial resolution can be increased because it is determined by the thickness of the fiber-shaped scintillator, and the linearity of the detection position can be improved by arranging the fiber-shaped scintillators in parallel with high precision. can be easily increased, and high count rate characteristics can be obtained depending on the configuration of the processing circuit for the light emitted from the end of the fiber-shaped scintillator.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a single fiber scintillator according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a one-dimensional detector in which fiber scintillators are arranged in one direction, and FIG. is 2 in which fiber-shaped scintillators are arranged in two directions.
FIG. 2 is a schematic diagram showing an example of a dimensional detector. 1 to 20...Fiber scintillator 31...Core material of plastic scintillator 32...Clad layer 33...Trajectories of charged particles A to II...Photomultiplier tube answer 1 diagram calculation 3"

Claims (1)

[Claims] (1) A plurality of optical fiber-like scintillators are arranged in parallel with a transparent scintillator as a core material, and the periphery thereof is covered with a cladding layer made of a material with a higher refractive index than the core material. A radiation detector configured so that a photodetector detects light emitted from the end of a scintillator.