Solid state neutron detector

• US 4,419,578 A
• Filed: 06/15/1981
• Issued: 12/06/1983
• Est. Priority Date: 06/15/1981
• Status: Expired due to Fees

• Current Assignee: Government of the United States of America
• Original Assignee: Government of the United States of America
• Inventors: Kress, Kenneth A.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Fields, Carolyn E.
• Application Number:
  US06/281,255
• Time in Patent Office: 904 Days
• Field of Search: 250/390, 250/370, 250/371, 250/391, 250/392, 357/29, 357/59, 357/15 R
• US Class Current: 250/390.01
• CPC Class Codes: G01T 3/08 with semiconductor detectors

Abstract

A solid-state neutron detector for detecting both fast and slow neutrons comprises two layers, one of which contains a neutron-sensitive first material and the other of which contains a semiconducting second material containing hydrogen, the first and second materials meeting to form a rectifying junction therebetween. The neutrons are detected by detecting electron-hole pairs migrating in opposite directions relative to the junction. The electron-hole pairs are created by energetic free protons produced by the fast neutrons travelling through the second material and by energetic reaction particles produced by the slow neutrons travelling through the first material. Stacking several of these detectors next to each other enhances overall sensitivity for detecting both fast and slow neutrons.

Claims

1. A neutron detector for detecting neutrons travelling in at least a first direction and comprising at least one neutron detecting assembly, said neutron detecting assembly comprising:

a neutron-sensitive first material which produces energetic reaction particles when bombarded by neutrons;

a semiconducting second material forming a rectifying junction with said first material and containing hydrogen, said second material producing energetic free protons when bombarded by neutrons, said second material also producing electron-hole pairs as a result of energy deposited therein by said reaction particles and free protons, said electron-hole pairs migrating in opposite directions relative to said junction to produce an electrical current across said junction; and

means for measuring said electrical current flowing across said junction.

2. A detector as claimed in claim 1 further comprising means for biasing said junction in order to almost fully deplete said second material.

3. A detector as claimed in claim 2 further comprising at least one additional neutron detecting assembly, said assemblies being stacked on top of each other so that each assembly is in the path of a neutron travelling in said first direction.

4. A detector as claimed in claim 3 further comprising subdivided, multiple electrode means for determining the point of origin of said free protons and said reaction particles.

5. A detector as claimed in claim 4 wherein said first material in each said assembly is surrounded by a corresponding second material.

6. A detector as claimed in claim 1 wherein said first material is a semiconducting non-metal thereby creating a p-n rectifying junction between said first and second materials.

7. A detector as claimed in claim 1, wherein said first material is a metal thereby creating a Schottky barrier rectifying junction between said first and second materials.

8. A detector as claimed in claim 1, 6 or 7, wherein said second material comprises hydrogen compensated amorphous silicon.

9. A detector as claimed in claim 1, 6 or 7 wherein said second material comprises a straight or branched chain semiconducting hydrocarbon.

10. A method of detecting neutrons travelling in at least a first direction, comprising the steps of:

generating energetic reaction particles by disposing at least one neutron-sensitive first material in the path of said neutrons travelling in said first direction;

generating energetic free protons by disposing at least one semiconducting second material containing hydrogen in said path of said neutrons travelling in said first direction, said second material forming a rectifying junction with said first material;

generating electron-hole pairs in said second material as a result of energy deposited therein by said reaction particles and free protons, said electron-hole pairs migrating in opposite directions relative to said junction thereby producing an electrical current across said junction; and

measuring said electric current flowing across said junction.

11. A method of detecting neutrons as claimed in claim 10 further comprising the step of biasing said junction in order to almost fully deplete said second material.

12. A method of detecting neutrons as claimed in claim 11 further comprising the step of disposing a plurality of said first and second materials in said paths of said neutrons travelling in said first direction, each first material being surrounded by a corresponding second material.

13. A method of detecting neutrons as claimed in claim 12 further comprising the step of determining the point of origin of said reaction particles and free protons.

14. A method of detecting neutrons as claimed in claim 10, further comprising the step of creating a Schottky barrier rectifying junction between said first and second materials by forming said first material from a metallic material.

15. A method of detecting neutrons as claimed in claim 10, further comprising the step of creating a p-n rectifying junction between said first and second materials by forming said first material from a semiconducting non-metal material.

16. A method of detecting neutrons as claimed in claim 10, 14 or 15, further comprising the step of forming said second material from a straight or branched chain hydrocarbon material.

17. A method of detecting neutrons as claimed in claim 10, 14 or 15, further comprising the step of forming said second material from a hydrogen compensated amorphous silicon material.