Subnanosecond scintillation detector

Patent metadata

Field	Value
Publication number	US-9739898-B2
Application number	US-201514670365-A
Country	US
Kind code	B2
Filing date	Mar 26, 2015
Priority date	Mar 26, 2014
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

First claim

What is claimed is:

1. One or more scintillation detectors useful for detecting energetic photons or particles, the detectors each comprising:
one or more scintillators that emit light (scintillation) in response to interactions with energetic photons or particles, the scintillation having a first component with a decay time less than 100 nanoseconds and a second component having a decay time longer than 100 nanoseconds;
one or more semiconductor photodetectors each comprising a passivation layer having a surface area for receiving the scintillation, wherein:
the passivation layer comprises a layer of silicon that is doped with a sheet density of at least 10 14 cm −2 that at least partially passivates the surface area, and
the one or more semiconductor photodetectors have built in gain through avalanche multiplication, such that charge generated in the one or more semiconductor photodetectors in response to the scintillation is amplified through impact ionization to produce an output pulse; and

a bandpass filter integrated with each of the one or more semiconductor photodetectors, wherein:
the bandpass filter comprises a metal-dielectric coating on the surface area,
the bandpass filter transmits light within a range of wavelengths corresponding to the first component of the scintillation, and
the bandpass filter suppresses transmission of light corresponding to the second component with wavelengths outside said range of wavelengths.

2. The one or more scintillation detectors of claim 1 , wherein:
the coating includes alternating dielectric and metal;
the bandpass filter couples the first component of the scintillation into one of the semiconductor photodetectors, the first component:
having a decay time faster than 1 nanosecond, and
having a peak intensity with the wavelength in a range of 190-250 nanometers; and

the one or more semiconductor photodetectors detect the first component of the scintillation.

3. The one or more scintillation detectors of claim 1 , wherein the bandpass filter transmits the first component having a wavelength of 300 nanometers or less and the photodetectors detect the scintillation comprising ultraviolet scintillation.

4. The one or more scintillation detectors of claim 1 , wherein the energetic particles or photons comprise gamma radiation.

5. The one or more scintillation detectors of claim 1 , wherein:
the coating includes alternating dielectric and metal.

6. The one or more scintillation detectors of claim 1 , wherein:
the coating includes one or more dielectric layers having one or more first thicknesses and one or more metal layers having one or more second thicknesses.

7. The one or more scintillation detectors of claim 1 , wherein:
the coating comprises transparent dielectric and reflective metal, and
the bandpass filter comprises a Fabry-Perot cavity and/or a photonic bandgap.

8. The one or more scintillation detectors of claim 1 , wherein the layer of silicon comprises at least one delta-doped layer.

9. The one or more scintillation detectors of claim 1 , wherein the layer of silicon comprises at least two delta-doped layers.

10. The one or more scintillation detectors of claim 1 , wherein the one or more scintillators comprise one or more doped or undoped Barium Fluoride (BaF 2 ) crystals.

11. The one or more scintillation detectors of claim 1 , wherein the one or more scintillators emit the scintillation having the first component including a peak wavelength near 220 nanometers and a second component including a peak wavelength near 300 nanometers.

12. The one or more scintillation detectors of claim 1 , wherein the one or more scintillators are chosen from at least one doped or undoped crystal selected from LaBr 3 , CsI, CeF 3 , PWO, LSO, and LYSO.

13. A system for performing Positron Emission Tomography (PET) and including the one or more scintillation detectors of claim 1 , further comprising:
pairs of the scintillators each comprising a first scintillator and a second scintillator, the first scintillator positioned to receive a first gamma photon and emit a first scintillation in response thereto, the second scintillator positioned to receive a second gamma photon and emit a second scintillation in response thereto, the first and the second gamma photons emitted as a pair from an electron-positron annihilation, and the positron from the electron-positron annihilation emitted by a radionuclide tracer introduced into a biological cell;
one of the semiconductor photodetectors positioned to detect the scintillation comprising the first scintillation and one of the detectors positioned to detect the scintillation comprising the second scintillation;
one or more computers for performing a three-dimensional calculation of a location of the radionuclide tracer, wherein:
the first and the second scintillations define a line of response and the intersections of the lines of response are used to determine the position of the radionuclide tracer with a first uncertainty, and
the relative detection times of the first scintillation and the second scintillation are used to determine the position of the radionuclide tracer in an additional dimension with a second uncertainty determined by the temporal resolution of the detectors.

14. A high energy particle detecting system comprising the one or more scintillation detectors of claim 1 , wherein the scintillation comprises ultraviolet electromagnetic radiation and/or gamma electromagnetic radiation.

15. The one or more scintillation detectors of claim 1 , wherein the coating, grown on the semiconductor, comprises a metal layer between two dielectric layers, the dielectric layers comprising at least one material selected from HfO 2 , Al 2 O 3 , SiO 2 , MgF 2 , and AlF 3 .

16. A method of fabricating one or more scintillation detectors useful for detecting energetic photons or particles, the detectors each comprising:
providing one or more scintillators that emit light (scintillation) in response to interactions with energetic photons or particles, such that at least a first component of the scintillation has a decay time less than 100 nanoseconds;
obtaining one or more semiconductor photodetectors each comprising a passivation layer having a surface area for receiving the scintillation, wherein:
the passivation layer comprises a layer of silicon that is doped with a sheet density of at least 10 14 cm −2 that at least partially passivates the surface area, and
the one or more semiconductor photodetectors have built in gain through avalanche multiplication, such that charge generated in the one or more semiconductor photodetectors in response to the scintillation is amplified through impact ionization to produce an output pulse; and

integrating a bandpass filter with each of the one or more semiconductor photodetectors, comprising applying a metal-dielectric coating on the surface area, wherein:
the bandpass filter comprises the coating on the surface area, and
the bandpass filter transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths.

17. One or more scintillation detectors useful for detecting energetic photons or particles, the detectors each comprising:
one or more scintillators that emit light (scintillation) in response to interactions with energetic photons or particles, the scintillation having a first component with a decay time less than 100 nanoseconds and a second component having a decay time longer than 100 nanose

Assignees

• California Inst Of Techn

Inventors

• Hoenk Michael
• Hennessy John
• Hitlin David

Classifications

• H01L27/14663

  Electricity · mapped topic

• G01T1/249 Primary

  specially adapted for use in SPECT or PET (SPECT imaging G01T1/1642; PET imaging G01T1/2985; detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects G01V5/20) · CPC title

• H01L27/14685

  Electricity · mapped topic

• G01T1/2018 Primary

  Scintillation-photodiode combinations · CPC title

• G01T1/248

  Silicon photomultipliers [SiPM], e.g. an avalanche photodiode [APD] array on a common Si substrate · CPC title