Stony Brook Update: T.K. Hemmick for the Tent Crew
Test box ready and given to Ilia • The test box was equipped with feet and the leaks were (mostly) sealed. • The windows were sealed with an extra ring of DP190 glue…works. • When the window seals were complete the next major leak was at the shaft for the source. • The source shaft repair involved cleaning away old grease, replacing O-ring with slightly thicker one. • The new shaft is sealed UNLESS it is torqued to one side or the other and then it leaks. • Handles were not installed. • Box was delivered to Ilia Wednesday.
ULPA Vac has an impact: • The ULPA Vaccuum arrived Wednesday. • The HBD vessel was closed for the cleaning to protect contents from flying dust and allow for the possibility of opening the glovebox for a permanent ceiling mount of the vacuum. • As second (final) “blow test” of the gain test box produced only minor increases in the dust level (50 400) as compared to the previous blow test (50 10000).
Water from ULPA vacuum • Although the vacuum was passed through the air lock disassembled (to avoid the burp of trapped air), its many interior surfaces nonetheless trapped some water. • Initial turn on of the vacuum spiked the water levels in the glovebox, but fortunately, the HBD was closed and flowing UHP Nitrogen. • The eventual solution was to turn on the vacuum and leave it on for hours. • The water went from 6.9 ppm over 40 ppm and then slowly decayed below 10 ppm before we turned the (now quite warm) unit off. • NOTE: Air exhaust from the vacuum registers zero dust particles of any size we can measure (0.3 microns and up) during any reasonable count time. • This is consistent with its rating as an ULPA device.
Cleaning Results • During the water purge, the vacuum was used to clean the HBD from one end to the other. • The initial result was that all visible surfaces seemed clear from debris. • The later result was that the dust meter when placed on the floor improved considerably: • Floor before: Class 200 • Floor after (Saturday morning): Class 20
Decision on Quad-GEMs • If we indeed go with the quad-GEM solution we must make modifications to the vessel for the new wire grids and re-route the internal HV connections. • This requires disassembly of the 4 stacks inside, removal of the HBD from the glovebox, and hardware work. • A preferred solution would be Ilia working with Bill Lenz on the mechanics • In this case, we should decide and act soon.
Idea for new grid mechanics • Bill Lenz correctly points out that the HV connection posts were not intended as precision devices and not placed with high precision. • Grid mount points, do require high precision. • A simple solution is to precisely position a piece that glues to the top of the HV block carrying the extra HV points as well as the extra mounting points for the grid.