Downhole gas-filled radiation detector with optical fiber

Patent metadata

Field	Value
Publication number	US-9841511-B2
Application number	US-201314646726-A
Country	US
Kind code	B2
Filing date	Dec 5, 2013
Priority date	Dec 6, 2012
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

Systems and devices are provided that relate to a gas-filled radiation detector with an internal optical fiber. The internal optical fiber may detect photons emitted during ionization avalanche events triggered by incident radiation. Such a radiation detector may include a housing, a fill gas within the housing, and an optical fiber within the housing. The fill gas may interact with radiation through an ionization avalanche that produces light. The optical fiber within the housing may capture the light and transmit the light out of the housing.

First claim

What is claimed is:

1. A radiation detector comprising:
a housing configured to serve as a cathode in an ionization avalanche;
a fill gas disposed within the housing, wherein the fill gas is configured to interact with radiation through the ionization avalanche that produces light; and
an optical fiber within the housing configured to capture the light and transmit the light out of the housing, wherein the optical fiber is doped with a conductive material and is configured to serve as an anode in the ionization avalanche.

2. The radiation detector of claim 1 , wherein the housing comprises a reflective inner surface configured to reflect the light from the ionization avalanche toward the optical fiber.

3. The radiation detector of claim 1 , wherein the conductive material comprises arsenic or gallium, or a combination thereof.

4. The radiation detector of claim 1 , wherein the optical fiber is doped with an impurity configured to enable optically stimulating luminescence when the optical fiber is struck by the light, by radiation that does not otherwise interact with the fill gas, or by both.

5. The radiation detector of claim 4 , wherein the impurity is configured to enable optically stimulating luminescence when the optical fiber is struck by ionizing radiation, wherein the ionizing radiation comprises:
the light; or
the radiation that does not otherwise interact with the fill gas; or
both.

6. The radiation detector of claim 4 , wherein the impurity is configured to enable optically stimulating luminescence when the optical fiber is struck by non-ionizing radiation.

7. The radiation detector of claim 4 , wherein the impurity comprises MgS doped with a rare earth, BaS doped with a rare earth, SrS doped with a rare earth, SrSe doped with a rare earth, αAl 2 O 3 , Al 2 O 3 :C, a quartz, a phosphor, BeO, CaF 2 :Mn, or CaSO 4 , or any combination thereof.

8. The radiation detector of claim 1 , wherein the optical fiber is doped with an optically amplifying material configured to amplify the light that is captured by the optical fiber from the ionization avalanche.

9. The radiation detector of claim 8 , wherein the optically amplifying material comprises neodymium (Nd 3+ ), ytterbium (Yb 3+ ), erbium (Er 3+ ), Thulium (Tm 3+ ), praseodymium (Pr 3+ ), or holmium (Ho 3+ ), or any combination thereof.

10. The radiation detector of claim 1 , wherein the optical fiber comprises one of a plurality of optical fibers in a bundle of optical fibers disposed within the housing, the optical bundle of optical fibers being configured to capture the light from the ionization avalanche event.

11. The radiation detector of claim 1 , wherein the optical fiber is wrapped back and forth along at least one dimension of the radiation detector to enlarge a surface area of the optical fiber within the radiation detector and capture more of the light from the ionization avalanche than otherwise.

12. The radiation detector of claim 1 , wherein the housing is generally cylindrical and the optical fiber comprises a central segment and a radial segment, the central segment being disposed centrally and axially within the cylindrical housing and being doped with a conductive material to enable the central segment to serve as an anode while also capturing some of the light from the ionization avalanche, and the radial segment being disposed generally axially within the cylindrical housing a radial distance from the central segment and wrapping back and forth axially within the cylindrical housing to enlarge a surface area of the optical fiber within the radiation detector and capture more of the light from the ionization avalanche than otherwise.

13. The radiation detector of claim 1 , wherein the optical fiber is connected to an electrical power source.

14. A downhole radiation detection system configured to detect radiation in a borehole of a geological formation, the system comprising:
a gas tube radiation detector configured to generate photons when struck by incident radiation, the photons being captured and transmitted out of the gas tube radiation detector as an optical signal by an optical fiber inside the gas tube radiation detector; and
a signal detection component configured to detect the optical signal from the optical fiber,
wherein the gas tube radiation detector includes:
a housing configured to serve as a cathode in an ionization avalanche;
a fill gas disposed within the housing, wherein the fill gas is configured to interact with radiation through the ionization avalanche that produces light; and
the optical fiber disposed within the housing configured to capture the light and transmit the light out of the housing, wherein the optical fiber is doped with a conductive material and is configured to serve as an anode in the ionization avalanche.

15. The system of claim 14 , wherein the gas tube radiation detector is disposed within a downhole tool and the signal detection component is remote from the downhole tool.

Assignees

• Schlumberger Technology Corp

Inventors

• Saenger Richard G

Classifications

• G01V5/04

  specially adapted for well-logging · CPC title

• G01T1/2002

  Optical details, e.g. reflecting or diffusing layers · CPC title

• G01T1/18 Primary

  with counting-tube arrangements, e.g. with Geiger counters (tubes H01J47/08; {with alarm provision G01T7/125}) · CPC title

• G01T1/205 Primary

  the detector being a gas · CPC title