Nuclear radiation moisture gauge calibration standard

• US 4,152,600 A
• Filed: 10/21/1976
• Issued: 05/01/1979
• Est. Priority Date: 10/21/1976
• Status: Expired due to Term

• Current Assignee: Troxler Electronic Laboratories, Inc.
• Original Assignee: Troxler Electronic Laboratories, Inc.
• Inventors: Berry, Richard L.
• Primary Examiner(s): Willis, Davis L.
• Application Number:
  US05/734,624
• Time in Patent Office: 922 Days
• Field of Search: 250/252, 250/253, 250/390, 250/391, 250/505
• US Class Current: 250/252.1
• CPC Class Codes: G01N 23/09 the radiation being neutrons

Abstract

A hydrophobic standard for calibrating nuclear radiation moisture gauges. In accordance with this invention, each standard has physical characteristics and dimensions effective for representing to a nuclear gauge undergoing calibration an infinite mass of homogeneous hydrogen content. Calibration standards are disclosed which are suitable for use with surface gauges and with depth gauges.

Claims

1. A hydrophobic calibration standard for thermal neutron moisture gauges comprising at least one body formed of a moderating material containing hydrogen in the molecular structure thereof and a substantially non-moderating material, with the materials arranged for a substantially uniform distribution of moderating material throughout the at least one body so as to impart thereto physical characteristics effective for representing a mass of homogenous hydrogen content to a gauge undergoing calibration.

2. A standard means according to claim 1 having physical dimensions effective for representing an infinite mass to a gauge undergoing calibration.

3. A standard means according to claim 1 comprising a body of material having a planar surface for receiving a surface gauge.

4. A standard means according to claim 1 comprising a body of material having a bore therein for receiving a depth gauge.

5. A hydrophobic standard means for calibrating thermal neutron moisture gauges comprising a plurality of bodies each effective for representing a corresponding, discrete hydrogen content to a gauge undergoing calibration for thereby providing a corresponding plurality of calibration points.

6. A hydrophobic calibration standard for nuclear radiation moisture gauges comprising a body of superposed interleaved thin layers of a moderating material containing hydrogen in the molecular structure thereof and of a substantially non-moderating material.

7. A standard according to claim 6 wherein said layers of moderating and non-moderating material have a substantially constant, substantially uniform thickness.

8. A standard according to claim 7 wherein said layers of moderating material alternate with said layers of non-moderating material for sandwiching layers of one material between pairs of layers of the other material.

9. A standard according to claim 7 wherein the number of layers of one material is a multiple of the number of layers of the other material for sandwiching layers of the other material between sets of multiple adjacent layers of the one material.

10. A standard according to claim 9 wherein the number of layers of non-moderating material is a multiple of the number of layers of moderating material.

11. A standard according to claim 6 wherein said layers of moderating material have a substantially constant, substantially uniform first thickness and said layers of non-moderating material have a substantially constant, substantially uniform second thickness differing from said first thickness.

12. A standard according to claim 6 wherein said moderating material is a polymer film and said non-moderating material is a metal sheet.

13. A standard according to claim 12 wherein said moderating material is a hydrocarbon polymer film.

14. A standard according to claim 6 further comprising fastener means for clamping said layers into engagement.

15. A hydrophobic calibration standard for nuclear radiation moisture gauges comprising a plurality of thin layers of a hydrocarbon polymer effective for moderating neutrons, a plurality of thin layers of a non-moderating material arranged in interleaved superposed relation with said polymer layers, and fastener means for clamping said layers into engagement, said layers together forming a body having physical characteristics and dimensions effective for representing to a nuclear gauge undergoing calibration an infinite mass of homogeneous hydrogen content.

16. A standard according to claim 15 wherein said polymer layers are of polyethylene and said non-moderating layers are of magnesium.