Neutron individual dose meter neutron dose rate meter, neutron detector and its method of manufacture

Abstract

PCT No. PCT/JP91/00574 Sec. 371 Date Dec. 27, 1991 Sec. 102(e) Date Dec. 27, 1991 PCT Filed Apr. 26, 1991 PCT Pub. No. WO91/17462 PCT Pub. Date Nov. 4, 1991A neutron individual dose meter and a neutron dose rate meter, both capable of implementing the effective dose equivalent response. The neutron individual dose meter is capable of being accomplished by providing a composite layer made up of a converter such as boron, and a proton radiator, on the surface of a semiconductor neutron detection element. The neutron dose rate meter is capable of being accomplished through such a structure as to surround a neutron detector with a neutron moderator and a thermal neutron absorber which has openings. Thus, a neutron individual dose meter and a neutron dose rate meter, both capable of implementing the effective dose equivalent response and measurement at lower operating voltage have been provided. Further, these meters are capable of being implemented by utilizing a single semiconductor detection element, respectively.

What is claimed is: 
     
       1. A neutron individual dose meter comprising: a neutron detector comprising a plurality of grains of a first material which generates charged particles through a nuclear reaction with thermal neutrons, and a second material different from the first material, both provided in a mixture state bonded to the surface of a semiconductor detection element; a processing circuitry for processing signals obtained from said neutron detector; and a power source for supplying power to said neutron detector and the processing circuitry. 
     
     
       2. The neutron individual dose meter claimed in claim 1, wherein said first material is characterized by being boron. 
     
     
       3. A neutron individual dose meter claimed in claim 1, wherein said second material is a hydride compound, and said first material is bonded by calcination on the surface of the semiconductor element. 
     
     
       4. A neutron individual dose meter comprising: a neutron detector comprising a grain-formed material which generates charged particles through a nuclear reaction with thermal neutrons and another material which generates no charged particles through interactions with fast neutrons, both formed on the surface of a semiconductor detection element; a processing circuitry for processing signals from said neutron detector; and a power source for supplying power to said neutron detector and processing circuitry. 
     
     
       5. The neutron individual dose meter claimed in claim 4 wherein, said grain-formed material characterized by being boron. 
     
     
       6. A meter according to claim 4, wherein said another material has a thermal expansion coefficient approximately equal to that of said semiconductor detection element or an elasticity which absorbs a thermal expansion of said grain-formed material, both said grain-formed material and said another material are bonded by calcination to a surface of said semiconductor detection element. 
     
     
       7. A neutron dose rate meter comprising: a neutron detector having a plurality of grains of a first material which generates charged particles in a semiconductor radiation detection element through a nuclear reaction with thermal neutrons and a second material different from the first material, both provided in a mixture state in the surface of the semiconductor detector element; a thermal neutron absorber disposed in the direction of incidence of said neutrons with respect to said neutron detector; a processing circuitry for processing signals from said neutron detector; and a power source for supplying power to said neutron detector and processing circuitry. 
     
     
       8. A neutron dose rate meter comprising: a neutron detector having a plurality of grains of a first material which generates charged particles in a semiconductor radiation detection element through a nuclear reaction with thermal neutrons and a second material different from the first material, both provided in a mixture state on the semiconductor radiation detection element; a thermal neutron absorber disposed so as to surround said neutron detector; a processing circuitry for processing signals from said neutron detector; and a power source for supplying power to said neutron detector and processing circuitry. 
     
     
       9. The neutron dose rate meter of claim 8 wherein, said thermal neutron absorber is characterized by having openings. 
     
     
       10. A neutron dose rate meter claimed in claim 8, further comprising a neutron moderator, said neutron moderator and said thermal neutron absorber both being disposed so as to surround said neutron detector. 
     
     
       11. A method of fabricating a neutron detector characterized by comprising steps of: bonding by calcination grain-formed boron which generates charged particles through a nuclear reaction with thermal neutrons on the surface of a semiconductor detection element; and infiltrating a hydride compound into the interstices of the bonded grain-formed boron to be retained firmly therein. 
     
     
       12. A neutron individual dose meter, comprising: a neutron detector having a layer made up of grain-formed material which generates charged particles through a nuclear reaction with thermal neutrons and another material which generates charged particles through an interaction with fast neutrons, said another material being infiltrated into interstices in the grains of said grain-formed material, the layer being formed on a surface of a semiconductor detection element;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and processing circuitry.   
     
     
       13. A neutron individual dose meter claimed in claim 12, wherein said grain-formed material is boron. 
     
     
       14. A neutron individual dose meter claimed in claim 12, wherein said another material is a hydride compound, and said grain-formed material is bonded by calcination on the surface of the semiconductor detection element. 
     
     
       15. A neutron individual dose meter claimed in claim 12, wherein a neutron sensitivity of said dose meter is adjusted to a desired dose equivalent response by varying an amount of said grain-formed material and said another material in said layer. 
     
     
       16. A neutron individual dose meter claimed in claim 12, wherein a grain thickness is varied so as to improve a detection sensitivity to thermal neutron. 
     
     
       17. A neutron individual dose meter, comprising: a neutron detector having a layer made up of a first material which generates charged particles through a nuclear reaction with thermal neutrons and a second material which generates charged particles through an interaction with fast neutrons, said first material being provided in a substantially plate form having openings therein, said second material being provided in said openings, the layer being formed on a surface of a semiconductor detection element;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and processing circuitry.   
     
     
       18. A neutron individual dose meter claimed in claim 17, wherein a neutron sensitivity of said dose meter is adjusted to a desired dose equivalent response by varying areas of the openings of said second material. 
     
     
       19. A neutron dose rate meter, comprising: a neutron detector having a layer made up of a grain-formed material which generates charged particles through a nuclear reaction with thermal neutrons and another material which generates charged particles through an interaction with fast neutrons, said another material being infiltrated into interstices in the grains of said grain-formed material, said layer formed on a surface of a semiconductor detection element;   a neutron moderator provided either on or above said neutron detector in the direction of incidence of said neutrons;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and processing circuitry.   
     
     
       20. A neutron dose rate meter, comprising: a neutron detector having a layer made up of a grain-formed material which generates charged particles through a nuclear reaction with thermal neutrons and another material which generates charged particles through an interaction with fast neutrons, said another material being infiltrated into interstices in the grains of said grain-formed material, said layer being formed on a surface of a semiconductor detection element;   a neutron moderator disposed so as to surround said neutron detector;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and processing circuitry.   
     
     
       21. A neutron dose rate meter as claimed in claim 20, wherein said grain-formed material is boron, and said another material is a hydride compound. 
     
     
       22. A neutron dose rate meter, comprising: a neutron detector having a plurality of grains of a first material which generates charged particles in a semiconductor detection element through a nuclear reaction with thermal neutrons and a second material different from said first material, both provided in a mixture state on said semiconductor detection element;   a human body simulating phantom firmly attached to said neutron detector;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and said processing circuitry.   
     
     
       23. A neutron dose rate meter as claimed in claim 22, wherein said phantom is constituted of acrylic having a surface area of 40 cm×40 cm and a height of 15 cm, or a vessel of the same size containing water, and said neutron detector being fixed firmly on a surface of said phantom. 
     
     
       24. A neutron detector comprising a layer made up of a grain-formed material which generates charged particles through a nuclear reaction with thermal neutrons and another material which generates charged particles through an interaction with fast neutrons, said another material being infiltrated into interstices in the grains of said grain-formed material, the layer being formed on a surface of a semiconductor detection element. 
     
     
       25. A neutron detector comprising a layer made up of a first material which generates charged particles through a nuclear reaction with thermal neutrons and a second material which generates charged particles through an interaction with fast neutrons, said first material being provided in a substantially plate form having openings therein, said second material being provided in said openings, the layer being formed on a surface of a semiconductor detection element. 
     
     
       26. A neutron individual dose meter, comprising: a neutron detector having a semiconductor detection element made up of a single wafer of semiconductor, electrodes formed on obverse and reverse sides of said wafer, at least one electrode on a p-n junction side of said electrodes being formed so as to cover a portion of a depletion region therein, said at least one of said electrodes having a reduced area so that an amount of charged particles entering said semiconductor element is increased, a power source for applying voltage to said electrodes;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and said processing circuitry.   
     
     
       27. A neutron detector, comprising: a single wafer of semiconductor;   electrodes provided on obverse and reverse surfaces of said wafer;   a semiconductor detection element, in which at least one of said electrodes on a p-n junction side of said electrodes is formed so as to cover a portion of a depletion region therein, said at least one of said electrodes having a reduced area so that an amount of charged particles entering said semiconductor element is increased; and   a power source for applying voltage to said electrodes.   
     
     
       28. A neutron individual dose meter, comprising: a neutron detector having a semiconductor detection element made up of a single wafer of semiconductor, electrodes formed on obverse and reverse sides of said wafer, a p-n junction formed inside the obverse side of said semiconductor element, at least one of said electrodes being connected to said p-n junction with a small area compared with that of said p-n junction and being formed so as to cover a portion of a depletion region therein, a power source for applying voltage to said electrodes;   a processing circuitry for processing signals from said neutron detector; and   a power source for supplying power to said neutron detector and processing circuitry.   
     
     
       29. A neutron detector, comprising: a single wafer of semiconductor;   electrodes provided on obverse and reverse surfaces of said wafer;   a semiconductor detection element, in which a p-n junction is formed inside the obverse side of said semiconductor element, at least one of said electrodes being connected to said p-n junction with a small area compared with that of said p-n junction and being formed so as to cover a portion of a depletion region therein; and   a power source for applying voltage to said electrodes. .Iadd.   
     
     
       30.  A neutron detecting apparatus comprising one semiconductor detection element having different materials for producing charged particles in accordance with incident neutrons and for detecting the charged particles produced by the different materials, wherein the neutron detecting apparatus has at least one sensitivity value for neutrons having an energy over 1 MeV which is at least about 20 times greater than at least one sensitivity value for neutrons having an energy under 10 KeV. .Iaddend..Iadd.31. A neutron detecting apparatus as claimed in claim 30, wherein the different materials includes a plurality of a first material for producing the charged particles in accordance with the incident neutrons having the energy under 10 KeV, and a second material for producing the charged particles in accordance with the incident neutrons having the energy over 1 MeV. .Iaddend..Iadd.32. A neutron detecting apparatus as claimed in claim 31, wherein the first material and the second material are provided in a mixture state and are bonded to the surface of the one semiconductor detection element. .Iaddend..Iadd.33. A neutron detecting apparatus as claimed in claim 31, wherein the first material is boron. .Iaddend..Iadd.34. A neutron detecting apparatus as claimed in claim 31, wherein the second material is a hydride compound. .Iaddend.