Photo-detector Tube Construction Laboratory Considerations Dean Walters Argonne National Laboratory

D. Walters Collaboration Meeting 11 June Requirements of a Tube Construction Laboratory Center will need to include: –Wet chemistry cleaning –Plasma Etching –Vacuum Firing –Test Equipment –Photocathode deposition and photo-detector assembly system The center should locate all of the operations in a central location to minimize handling and to control the surface qualities for repeatable results. –The center needs to control dust and particulate contamination. –It needs to control temperature and humidity, important in the Midwest. –It needs services for water, electrical, dry nitrogen, liquid nitrogen, compressed air, process gases, and exhaust gas venting. –It should be near the materials characterization laboratories. This will be the central point where the parts from external suppliers will be delivered This is a tube construction center where the anticipated production rate will be 1-2 units a week.

D. Walters Collaboration Meeting 11 June Initial Steps Prior to starting the construction of the tube the parts need to be prepared.

D. Walters Collaboration Meeting 11 June Outline of Processes for the Manufacture of a Photo-detector Tube Lower Body Construction Cleaning Facility Photocathode Fabrication Photo Detector Assembly System

D. Walters Collaboration Meeting 11 June Lower Tube Assembly The parts making up the Lower Tube Assembly will be pre-processed prior to being assembled. –The anode plate will be glass fritted sealed to the side-wall. –The NEG strip will be cut and formed to fit within the glass locating pins. –The MCP’s will be plasma cleaned and then assembled into the Tube Assembly. MCP’s Anode plate fritted to side-wall NEG Strip The top face of the side-wall will be coated with chromium & indium to facilitate the top seal. Indium on side-wall

D. Walters Collaboration Meeting 11 June Top Plate Wet chemistry and plasma cleaning The top plate will need to be prepared for the top seal. –Using a mask to protect the area of the photocathode, chromium & indium will be deposited onto the glass plate. –Then heat cleaning can be employed to purify the indium which will aid in the integrity of the joint.

D. Walters Collaboration Meeting 11 June Photocathode Deposition & Photo-detector Assembly System Dual chamber manual process system Deposition Chamber –Ability to degas sources without contaminating other parts. –Once shutter is open, it will act a shield for the other parts to prevent accidental deposition –There will be the ability to monitor the deposition through current measurement while the photocathode is being illuminated Scrubbing and Bonding Chamber –This will house the electron source to scrub the MCP. –The detachable cylinder will apply the force necessary to affect a pressure indium seal. System will be bakeable to 350 C

D. Walters Collaboration Meeting 11 June Industrial Photo-detector Processing System

D. Walters Collaboration Meeting 11 June Conclusions As steps are worked out more of the requirements for the construction of the tube become better known. –The anode will be silk screen onto the bottom plate. –The side-wall will be frit sealed onto the bottom plate –The MCP’s will be coated using ALD and processed in an high temperature that will leave them in a very clean condition. –An indium joint is being worked on that will be the final tube seal. –The processes within the final processing station are now becoming better known. Final vacuum bake of all components Activation on NEG Final plasma clean-up of MCP Deposition of photocathode using in-situ monitoring Indium seal to complete the tube Determination of indium seal integrity Determination of photo-detector operation Controlled venting of the system