Thermoluminescence radiation dosimetry using transparent glass containing nanocrystalline phosphor

• US 5,656,815 A
• Filed: 02/08/1996
• Issued: 08/12/1997
• Est. Priority Date: 02/08/1996
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Huston, Alan L., Justus, Brian L.
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US08/598,677
• Time in Patent Office: 551 Days
• Field of Search: 250/337
• US Class Current: 250/337
• CPC Class Codes: G01T 1/11 Thermo-luminescent dosimeters thermo-luminescent compositions C09K11/00

Abstract

Radiation is detected using a light transparent thermoluminescent dosimeter that comprises a nanocrystalline phosphor dispersed in a light transparent glassy matrix, such as Vycor glass. The dosimeter is placed in an environment in which radiation is present for a period of time, removed from the environment and then heated to emit light, the intensity of which is indicative of the radiation dose. The method of the invention is useful for detecting and recording the dosage of both UV and ionizing radiation. In one embodiment in which the dosimeter is in the form of a flat plate. Ambient α or β radiation populates traps and, upon heating of the flat dosimeter, the emitted light is guided to the edges of the dosimeter by total internal reflection, where it is detected and recorded.

Claims

1. A method for detecting the presence of radiation in an environment in which radiation is present, said method comprising:

placing a thermoluminescent radiation dosimeter in said environment for a predetermined period of time,

removing said irradiated dosimeter from said environment and then heating said irradiated dosimeter so that it emits thermoluminescent light of an intensity indicative of the absorbed dose and determining the absorbed dose from said emitted light,

wherein said dosimeter comprises nanocrystalline thermoluminescent phosphor particles dispersed throughout a light transparent, glassy matrix.

2. A method according to claim 1 wherein said phosphor comprises a phosphor which, when heated after being exposed to ionizing radiation, emits thermoluminescent light, the intensity of which is indicative of the absorbed dose.

3. A method according to claim 2 wherein said nanocrystalline particles are present in pores in said glassy matrix.

4. A method according to claim 3 wherein said radiation comprises UV or ionizing radiation.

5. A method according to claim 4 wherein said radiation is selected from the group consisting essentially of UV, α

, β

, γ and

X-radiation and neutron radiation.

6. A method according to claim 5 wherein said glassy matrix is partially consolidated to seal said nanocrystalline particles within.

7. A method according to claim 6 wherein said phosphor comprises Group II_A, II_B, VI_A, VI_B and II-VI semiconductors.

8. A method according to claim 6 wherein said phosphor is selected from the group consisting essentially of ZnS, doped with at least one activating metal ions of Cu, Mn, Ag, Pb and Eu, LiF doped with at least one activating metal ions of Ti, Mg, Cu and P, Li₂ B₄ O₇ :

Mn, SrS, BaS, GaS, CaF₂ doped with Mg or rare earth metal ions, alkali metal sulfates doped with at least one of Cu, Dy or Th ions, MgS doped with one or both of Eu and Sm activating metal ions, and alkali metal halides doped with lanthanide metal ions.

9. A method according to claim 8 wherein said radiation consists of UV radiation.

10. A method for detecting radiation and determining absorbed dosage using a thermoluminescent dosimeter which comprises nanocrystalline thermoluminescent phosphor particles dispersed throughout a light transparent, glassy matrix, said method comprising the steps of:

(i) exposing said dosimeter to a radiation containing environment for a predetermined period of time;

(ii) removing the irradiated dosimeter from said environment;

(iii) heating said irradiated dosimeter to produce a thermoluminescent glow curve;

(iv) recording said glow curve and comparing it with glow curves obtained from a known radiation dose, and

(v) determining the radiation dosage experienced by said dosimeter.

11. A method according to claim 10 wherein said phosphor comprises a phosphor which, when heated after being exposed to ionizing radiation, emits thermoluminescent light, the intensity of which is indicative of the absorbed dose.

12. A method according to claim 11 wherein said nanocrystalline particles are present in pores in said glassy matrix.

13. A method according to claim 12 wherein said radiation comprises UV or ionizing radiation.

14. A method according to claim 13 wherein said radiation is selected from the group consisting essentially of UV, α

, β

, γ and

X-radiation and neutron radiation.

15. A method according to claim 14 wherein said glassy matrix is partially consolidated to seal said nanocrystalline particles within.

16. A method according to claim 15 wherein said phosphor comprises Group II_A, II_B, VI_A, VI_B and II-VI semiconductors.

17. A method according to claim 15 wherein said phosphor is selected from the group consisting essentially of ZnS, doped with at least one activating metal ions of Cu, Mn, Ag, Pb and Eu, LiF doped with at least one activating metal ions of Ti, Mg, Cu and P, Li₂ B₄ O₇ :

Mn, SrS, BaS, CaS, CaF₂ doped with Mg or rare earth metal ions, alkali metal sulfates doped with at least one of Cu, Dy or Th ions, MgS doped with one or both of Eu and Sm activating metal ions, and alkali metal halides doped with lanthanide metal ions.

18. A method according to claim 17 wherein said radiation consists of UV radiation.

19. A method for detecting radiation in an environment in which said radiation is present, said method comprising placing a thermoluminescent radiation dosimeter in said environment for a predetermined period of time, removing said irradiated dosimeter from said environment and then heating said irradiated dosimeter so that it emits thermoluminescent light of an intensity indicative of the absorbed dose and determining the absorbed dose from said emitted light, wherein said dosimeter is in the form of a flat plate with parallel faces and comprises nanocrystalline thermoluminescent phosphor particles dispersed throughout a light transparent, glassy matrix, and wherein said emitted light is guided by total internal reflection to the edges of said dosimeter where it is detected.

20. A method according to claim 19 wherein said radiation is α

or β

radiation.

21. A thermoluminescent dosimeter which comprises nanocrystalline thermoluminescent phosphor particles dispersed throughout a light transparent, glassy matrix in the form of a flat plate with parallel faces, whereby thermoluminescent light emitted by said dosimeter is guided by total internal reflection to the edges of said dosimeter.