Detector for a bipolar time-of-flight mass spectrometer
View Patent ↗A replaceable, electronically-isolated, MCP-based spectrometer detector cartridge with enhanced sensitivity is disclosed. A mass detector is electro-optically isolated from a charge collector with an electron multiplier for converting a charged particle into a multiplicity of electrons and a scintillator for converting the multiplicity of electrons into a multiplicity of photons. A light sensor is provided to convert the multiplicity of photons back into electrons which are summed into a charge pulse. The light sensor is realized by any of a plurality of photo-responsive devices.
1. A detector for a time-of-flight mass spectrometer comprising:
an electron multiplier, for converting a charged particle into a multiplicity of electrons;
a scintillator, for converting the multiplicity of electrons into a multiplicity of photons; and
a collector disposed for receiving the multiplicity of photons and adapted for reconverting said photons into a second multiplicity of electrons and integrating said second multiplicity of electrons into a charge pulse corresponding to the mass of the charged particle;
wherein said collector comprises a light sensor selected from the group consisting of an avalanche photodiode, an avalanche photodiode array, a charge coupled device, a photovoltaic device, a CdS photoconductive cell, a PN photodiode, a PIN photodiode, a phototransistor, a vacuum photodiode, an image intensifier tube having a metal anode in place of a luminescent screen, a microchannel plate type photomultiplier, and a photomultiplier tube incorporating stage skipping.
2. The detector set forth in claim 1 , wherein said electron multiplier comprises a coating formed on a surface thereof, said coating being formed of a material selected from the group consisting of aluminum oxide (Al 2 O 3 ), magnesium oxide (MgO), tin oxide (SnO 2 ), quartz (SiO 2 ), barium fluoride (BaF 2 ), rubidium tin (Rb 3 Sn), beryllium oxide (BeO), diamond and combinations thereof.
3. The detector set forth in claim 1 , wherein said electron multiplier comprises a microchannel plate.
4. The detector set forth in claim 1 comprising a cartridge configured to receive said microchannel plate, said cartridge being readily removable from and installable in said detector.
5. The detector set forth in claim 1 , wherein said scintillator is configured to provide a frequency bandwidth which accommodates arrival times of the multiplicity of electrons.
6. The detector set forth in claim 1 , wherein said scintillator is constructed from a plastic scintillator material.
7. The detector set forth in claim 1 , further comprising a conductive coating on said scintillator configured to internally reflect photons generated therein.
8. The detector set forth in claim 7 , wherein the conductive coating on said scintillator is selected from the group consisting of aluminum, chrome and combinations thereof.
9. The detector set forth in claim 1 wherein the light sensor is an avalanche photodiode.
10. The detector set forth in claim 1 wherein the light sensor is an avalanche photodiode array.
11. The detector set forth in claim 1 wherein the light sensor is a charge coupled device.
12. The detector set forth in claim 1 wherein the light sensor is a photovoltaic device.
13. The detector set forth in claim 1 wherein the light sensor is a CdS photoconductive cell.
14. The detector set forth in claim 1 wherein the light sensor is a PIN photodiode.
15. The detector set forth in claim 1 wherein the light sensor is a phototransistor.
16. The detector set forth in claim 1 wherein the light sensor is a vacuum photodiode.
17. The detector set forth in claim 1 wherein the light sensor is an image intensifier tube having a metal anode in place of a luminescent screen.
18. The detector set forth in claim 1 wherein the light sensor is a microchannel plate type photomultiplier.
19. The detector set forth in claim 1 wherein the light sensor is a photomultiplier tube incorporating stage skipping.
20. A detector for a time-of-flight mass spectrometer comprising:
a microchannel plate disposed for receiving a charged particle and formed for converting the charged particle into a multiplicity of electrons;
a scintillator disposed for receiving the multiplicity of electrons from said microchannel plate for converting the multiplicity of electrons into a multiplicity of photons; and
a collector disposed for receiving the multiplicity of photons and adapted for reconverting the multiplicity of photons into a second multiplicity of electrons and integrating said second multiplicity of electrons into a charge pulse corresponding to the mass of the charged particle;
wherein said collector comprises a light sensor selected from the group consisting of an avalanche photodiode, an avalanche photodiode array, a charge coupled device, a photovoltaic device, a CdS photoconductive cell, a PN photodiode, a PIN photodiode, a phototransistor, a vacuum photodiode, an image intensifier tube having a metal anode in place of a luminescent screen, a microchannel plate type photomultiplier, and a photomultiplier tube incorporating stage skipping.