Arrayed neutron detector with multi shielding allowing for discrimination between radiation types

• US 7,645,993 B2
• Filed: 12/28/2007
• Issued: 01/12/2010
• Est. Priority Date: 12/28/2007
• Status: Expired due to Fees

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Spansion LLC (Infineon Technologies AG)
• Inventors: Gazda, Jerzy, Hossain, Tim Z.
• Primary Examiner(s): Porta; David P
• Assistant Examiner(s): Malevic; Djura
• Application Number:
  US11/966,672
• Publication Number:
  US 20090166550A1
• Time in Patent Office: 746 Days
• Field of Search: 250/370.05, 257/252
• US Class Current: 250/370.05
• CPC Class Codes: G01T 3/08 with semiconductor detectors

Abstract

Neutron detectors including one or more gamma shields over memory dies and methods of making the neutron detectors are provided. The neutron detectors can contain two or more memory dies, neutron-reactant layers over the two or more memory dies, and one or more gamma shields over at least a portion of or an entire of the two or more memory dies. By containing the gamma shield over the at least a portion of or an entire of the two or more memory dies, the neutron detector can detect and discriminate neutrons in the presence of gamma rays.

Claims

1. A neutron detector comprising:

two or more memory dies comprising a plurality of memory cells, the memory dies comprising neutron-reactant layers over the memory cells; and

one or more gamma shields over at least a portion of or an entire of the two or more memory dies, the gamma shield substantially preventing gamma rays from penetrating into the memory die under the gamma shield.

2. The neutron detector of claim 1, wherein the two or more memory dies comprise a flash memory.

3. The neutron detector of claim 1, wherein the neutron-reactant layer comprises a borophosphosilicate glass that reacts with a neutron and emits a ⁴Alpha particle, and wherein the memory die uncovered with the gamma shield detects the ⁴Alpha particle and gamma rays, and the memory die covered with the gamma shield detects the ⁴Alpha particle and discriminates against gamma rays.

4. The neutron detector of claim 1, wherein the neutron-reactant layer comprises ¹⁰Boron that reacts with a neutron and emits a ⁴Alpha particle, and wherein the memory die uncovered with the gamma shield detects the ⁴Alpha particle and gamma rays, and the memory die covered with the gamma shield detects the ⁴Alpha particle and discriminates against gamma rays.

5. The neutron detector of claim 4, wherein the neutron-reactant layer comprises about 80 wt % or more and about 100 wt % or less of ¹⁰Boron in a total Boron concentration.

6. The neutron detector of claim 1, wherein the gamma shield comprises lead.

7. The neutron detector of claim 1, wherein about 5% of memory dies or more and about 95% of memory dies or less is covered with the gamma shield.

8. The neutron detector of claim 1 further comprising a passivation layer over the two or more memory dies.

9. A method of making a neutron detector, comprising:

forming neutron-reactant layers over two or more memory dies; and

forming one or more gamma shields over at least a portion of or an entire of the two or more memory dies, the gamma shield substantially preventing gamma rays from penetrating into the memory die under the gamma shield.

10. The method of claim 9, wherein the two or more memory dies comprise a flash memory.

11. The method of claim 9, wherein the neutron-reactant layer comprises a borophosphosilicate glass that reacts with a neutron and emits a ⁴Alpha particle, and wherein the memory die uncovered with the gamma shield detects the ⁴Alpha particle and gamma rays, and the memory die covered with the gamma shield detects the ⁴Alpha particle and discriminates against gamma rays.

12. The method of claim 9, wherein the neutron-reactant layer comprises ¹⁰Boron that reacts with a neutron and emits a ⁴Alpha particle, and wherein the memory die uncovered with the gamma shield detects the ⁴Alpha particle and gamma rays, and the memory die covered with the gamma shield detects the ⁴Alpha particle and discriminates against gamma rays.

13. The method of claim 9, wherein the neutron-reactant layer comprises about 80 wt % or more and about 100 wt % or less of ¹⁰Boron in a total Boron concentration.

14. The method of claim 9, wherein the gamma shield comprises lead.

15. The method of claim 9, wherein the gamma shield covers about 5% of memory dies or more and about 95% of memory dies or less.

16. The method of claim 9 further comprising forming a passivation layer over the two or more memory dies.

17. A method of detecting strength of a neutron field, comprising:

providing a neutron detector comprising two or more memory dies, neutron-reactant layers over the two or more memory dies, and one or more gamma shields over at least a portion of or an entire of the two or more memory dies, the memory die comprising a plurality of memory cells, the gamma shield substantially preventing gamma rays from penetrating into the memory die under the gamma shield;

reading a state of each of the memory cells of the memory dies to determine a number of memory cells changing from an initial state to a disturbed state; and

determining the strength of the neutron field by using the number of memory cells having the disturbed state.

18. The method of claim 17, wherein reading the state of each of the memory cells comprises reading the state of each of the memory cells uncovered with the gamma shield and reading the state of each of the memory cells covered with the gamma shield.

19. The method of claim 17, wherein determining the strength of the neutron field comprises determining a percentage of the memory cells having the disturbed state.

20. The method of claim 17, wherein determining the strength of the neutron field comprises comparing the disturbed percentage of the memory cells uncovered with the gamma shield and the disturbed percentage of the memory cells covered with the gamma shield.