Batch production of microchannel plate photo-multipliers
In-situ methods for the batch fabrication of flat-panel micro-channel plate (MCP) photomultiplier tube (PMT) detectors (MCP-PMTs), without transporting either the window or the detector assembly inside a vacuum vessel are provided. The method allows for the synthesis of a reflection-mode photocathode on the entrance to the pores of a first MCP or the synthesis of a transmission-mode photocathode on the vacuum side of a photodetector entrance window.
1. A method of fabricating a reflection-mode photocathode in a microchannel plate photomultiplier tube detector, the method comprising:
(a) forming an unsealed detector outer package comprising:
a window having an outer surface and an inner surface, wherein the inner surface faces opposite the outer surface; and
a detector body comprising: (i) a base plate having an outer surface and an inner surface, wherein the window and the base plate are spaced apart and face each other, such that the inner surface of the window faces the inner surface of the base plate; and (ii) a side wall that separates the window from the base plate, wherein the side wall, the base plate, or both has one or more conduits extending through it;
(b) providing a microchannel plate detector in the unsealed detector package, the microchannel plate detector comprising:
a microchannel plate having a cathode surface that is coated with a photocathode precursor material and that faces the inner surface of the window; and
at least one spacer that separates the microchannel plate from the window; and
at least one spacer that separates the microchannel plate from the base plate;
(c) sealing the window to the detector body to form a sealed detector outer package;
(d) evacuating the sealed detector outer package through the one or more conduits;
(e) introducing an alkali metal-containing vapor into the evacuated sealed detector outer package through the one or more conduits, wherein the alkali metal-containing vapor reacts with the photocathode precursor material to form a photocathode material on the cathode surface of the microchannel plate; and
sealing the one or more conduits.
2. The method of claim 1 , wherein the photocathode precursor material comprises a Group V element.
3. The method of claim 2 , wherein the photocathode precursor material is Sb and the alkali metal-containing vapors comprise K and Cs.
4. The method of claim 3 , wherein the photocathode material comprises K 2 CsSb.
5. The method of claim 2 , wherein the photocathode precursor material is Sb and the alkali metal-containing vapor comprises vaporized K 2 Cs molecules.
6. The method of claim 5 , wherein the photocathode material comprises K 2 CsSb.
7. The method of claim 1 , wherein the photocathode precursor material comprises a Group III-V semiconductor alloy.
8. The method of claim 7 , wherein the photocathode precursor material is a GaN semiconductor alloy, the alkali metal-containing vapor comprises Cs, and the photocathode material comprises a Cs-activated GaN semiconductor alloy.