# US 5,349,194 A · Microgap ultra-violet detector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,194 A - Document ID: US5349194A - Status: Granted - Kind: A - Application number: 08/011,636 - Filed: 1993-02-01 - Granted: 1994-09-20 - Earliest claimed: 1993-02-01 - Assignees: The United States of America as represented by the United States Department of Energy - Inventors: Craig R. Wuest; Richard M. Bionta - Web page: https://patentgrep.com/patent/US5349194A ## CPC - H01J 47/06: Proportional counter tubes - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A microgap ultra-violet detector of photons with wavelengths less than 400 run (4000 Angstroms) which comprises an anode and a cathode separated by a gas-filled gap and having an electric field placed across the gap. Either the anode or the cathode is semi-transparent to UV light. Upon a UV photon striking the cathode an electron is expelled and accelerated across the gap by the electric field causing interactions with other electrons to create an electron avalanche which contacts the anode. The electron avalanche is detected and converted to an output pulse. ## Claims ### Claim 1 A detector for ultra-violet photons comprising: a cathode composed of material that expels electrons when impinged on by ultra-violet photons; an anode composed of material that collects electrons; one of said cathode and anode being constructed of a layer of material which is semitransparent to ultra-violet photons; said layer of material semitransparent to ultra-violet photons extending over an entire surface of said one of said cathode and anode constructed thereof; a window composed of material transparent to ultra-violet photons; one of said cathode and anode being located adjacent to said window; aid cathode and said anode being located in spaced relation to form a gap therebetween; said gap being filled with a gas; means for applying an electric potential between said anode and said cathode for producing an electrical field in said gap; and means for detecting electron avalanches on said anode. ### Claim 2 (depends on 1) The detector of claim 1, wherein said anode is constructed of material sen-ti-transparent to ultra-violet photons. ### Claim 3 (depends on 2) The detector of claim 2, wherein said anode material is selected from the group consisting of gold, copper, silver and platinum. ### Claim 4 (depends on 3) The detector of claim 3, wherein said anode material is gold having a thickness of about 200 .ANG.. ### Claim 5 (depends on 2) The detector of claim 2, wherein said cathode is constructed of material selected from the group of yttrium, cesium iodide, gold, silver and chromium. ### Claim 6 (depends on 5) The detector of claim 5, wherein said cathode is constructed of yttrium having a thickness of about 1000 .ANG.. ### Claim 7 (depends on 1) The detector of claim 1, wherein said gap has a width of 5 .mu.m to 1 mm. ### Claim 8 (depends on 7) The detector of claim 7, wherein said gap has a width of about 100 microns. ### Claim 9 (depends on 1) The detector of claim 1, wherein said gas has a pressure in the range of 0.1 atm to 2 atm, and is selected from the group consisting of 90% argon/10% methane, argon/isobutane mixtures, and CO.sub.2 /CF.sub.4. ### Claim 10 (depends on 9) The detector of claim 9, wherein said gas is composed of 90% argon/10% methane at a pressure of 1 atm. ### Claim 11 (depends on 1) The detector of claim 1, wherein said electric field, E, is determined by the electric potential, V, applied between said anode and said cathode divided by the dimension, D, of said gap, namely, E=V/D. ### Claim 12 (depends on 11) The detector of claim 11, wherein said electric potential, V, is 500 volts and said dimension, D, is 100 microns, whereby said electric field is 5.times.10.sup.6 volts/meter. ### Claim 13 (depends on 1) The detector of claim 1, wherein said cathode is constructed of material semi-transparent to ultra-violet photons. ### Claim 14 (depends on 13) The detector of claim 13, wherein said anode is constructed of opaque metallic material selected from the group consisting of gold, silver, copper, chromium and platinum. ### Claim 15 (depends on 13) The detector of claim 13, wherein said cathode is constructed of material selected from the group consisting of yttrium, cesium iodide, gold, silver and chromium. ### Claim 16 (depends on 15) The detector of claim 15, wherein said cathode is constructed of semi-transparent yttrium having a thickness of 200 .ANG.. ### Claim 17 (depends on 16) The detector of claim 16, wherein said anode is constructed of gold. ### Claim 18 (depends on 17) The detector of claim 17, wherein said gold anode has a thickness of 1000 .ANG.. ### Claim 19 A micro-gap ultra-violet detector comprising: a photocathode; an anode; one of said photocathode and said anode being constructed of material which is semi-transparent to ultra-violet photons; said photocathode and said anode being located in coplanar spaced relationship along all surfaces thereof an forming a gap therebetween; said gap being filled with gas; means for applying an electrical potential between said anode and said photocathode for producing an electric field in said gap; and means for detecting and removing a charge on said anode created by a photon striking said photocathode. ### Claim 20 (depends on 19) The detector of claim 19, wherein said anode is constructed of semi-transparent material. ### Claim 21 (depends on 19) The detector of claim 19, wherein said photocathode is constructed of semi-transparent material. ### Claim 22 A micro-gap detector for detecting photons with wavelengths less than 400 nm, comprising: a housing having an opening therein; a photocathode and an anode being located in coplanar spaced relationship at all points thereon, and located in said opening of said housing and forming a gap therebetween; one of said coplanar photocathode and anode being composed of material which is semi-transparent to ultra-violet photons; said gap being filled with a gas; means for producing an electric filed in said gap; and means for detecting and removing electrons collected on said anode. ### Claim 23 A micro-gap detector for detecting photons with wavelengths less than 400 nm, comprising: a housing having an opening therein; a photocathode and an anode being located in coplanar spaced relationship, and located in said opening of said housing and forming a gap therebetween; one of said coplanar photocathode and anode being composed of material which is semi-transparent to ultra-violet photons; said gap being filled with a gas; means for producing an electric field in said gap; and means for detecting and removing electron collected on said anode; each of said photocathode and said anode being configured to have a width and length, said photocathode having a width dependent upon the configuration of the anode, and said anode being configured in differing widths when selected from the group consisting of a continuous plane, and a plurality of sections.