Radiation measurement apparatus and method
An apparatus for measuring radiation includes a plurality of detectors ( 2 ), each detector ( 2 ) including: a scintillating material ( 4 ) for emitting light in response to incident radiation ( 6 ), and a photodetector ( 8 ) for receiving light emitted by the scintillating material ( 4 ) and outputting an electrical pulse in response to light received from the scintillating material ( 4 ), wherein a parameter characterising the electrical pulse is related to an energy associated with the incident radiation ( 6 ); and a power supply ( 10 ) for supplying power to a plurality of the photodetectors ( 8 ). The apparatus reduces the volume of hardware to be transported to the measurement location and therefore provides particular advantages for scanning pipelines and other structures located deep underwater.
1. A subsea apparatus for measuring radiation, comprising:
a plurality of detectors, each detector comprising:
a scintillating material configured to emit light in response to incident radiation, and
a photodetector configured to receive light emitted by the scintillating material and output an electrical pulse in response to light received from the scintillating material, a parameter characterizing the electrical pulse being related to an energy associated with the incident radiation; and
a power supply configured to supply power to a plurality of said photodetectors connected in parallel to the at least one power supply.
2. The subsea apparatus according to claim 1 , further comprising a plurality of power supplies, each power supply being configured to supply power to a respective plurality of photodetectors.
3. The subsea apparatus according to claim 1 , further comprising at least one capacitor configured to stabilize the voltage supplied by a respective power supply.
4. The subsea apparatus according to claim 1 , further comprising at least one data acquisition part configured to receive electrical pulses output by a respective detector and count a number of said electrical pulses having a value for said parameter within a predetermined range,
wherein said data acquisition part is configured to:
count a respective number of electrical pulses having a value for said parameter within each one of a plurality of sampling ranges,
identify a value of interest for said parameter based on the counted numbers of electrical pulses in said sampling ranges,
determine a measurement range centered on said value of interest, and
count a number of electrical pulses having a value for said parameter within said measurement range.
5. The subsea apparatus according to claim 4 , wherein said data acquisition part is configured to count said respective numbers of electrical pulses successively.
6. The subsea apparatus according to claim 4 , wherein said value of interest of said parameter corresponds to the full energy of the incident radiation.
7. The subsea apparatus according to claim 1 , wherein said radiation is gamma radiation.
8. The subsea apparatus according to claim 1 , wherein said photodetector is a photomultiplier tube.
9. The subsea apparatus according to claim 1 , further comprising a source of radiation.
10. The subsea apparatus according to claim 1 , wherein said plurality of detectors is disposed in an arc around a space capable of receiving a structure to be scanned.
11. The subsea apparatus according to claim 10 , further comprising:
a source of radiation, said plurality of detectors and said source of radiation being disposed on opposite sides of said space; and
a rotation system configured to rotate said plurality of detectors and said source of radiation around a structure to be scanned, in fixed spatial relation to each other.
12. A method for measuring radiation, using the subsea apparatus according to claim 1 , comprising the steps of:
positioning the subsea apparatus at a subsea measurement location;
counting a respective number of electrical pulses having a value for said parameter within each one of a plurality of sampling ranges;
identifying a value of interest for said parameter based on the counted numbers of electrical pulses in said sampling ranges;
determining a measurement range centered on said value of interest; and
counting a number of electrical pulses having a value for said parameter within said measurement range.
13. The method according to claim 12 , wherein said respective numbers of electrical pulses are counted successively.
14. The method according to claim 12 , wherein the subsea measurement location is at a depth of 1000 m or greater.
15. The subsea apparatus according to claim 5 , wherein said value of interest of said parameter corresponds to the full energy of the incident radiation.