Ideas for finding UV from streamers in ProtoDUNE Ideas, drawings, photos, etc. by Francesco Pietropaolo, Jim Stewart, Heng-Ye Liao, Bo Yu... and possibly others (slides put together by Glenn H-S.) 1
What are the streamer-vulnerable locations in SP? We need to know where it is happening to know how to scale “HV downtime”. (~10% in PD-SP) At a cathode corner: FD-SP has 2x more cathodes. -> 20% HV downtime. Anywhere along cathode vertical edge or endwall HV edge: FD-SP has 2x as many cathodes, 2x height. -> 40% HV downtime. Anywhere on cathode horizontal edge, or on horizontal FC or ground plane: FD-SP 10x length, 2x cathode or 2x width. -> 200% HV downtime. On beam plug. FD-SP has 0x as many beam plugs. -> 0% downtime. 2
Replace NP04 camera 202 with PMT Cameras 201, 202, and 203 are fisheye cameras installed in acrylic tubes that intrude into the cryostat from ports 14.2, 18.2, and 9.3 (resp.). They can be removed and replaced without draining the detector. Cam-202 is upstream beam right, near beam plug. Francesco: Replace camera tube 202 with a TPB-coated PMT. Acrylic is non UV-transparent, so entire tube must be removed, replaced. Some exposure of argon to air inevitable [unless some kind of large “glove bag” can be rigged]. The PMT could be positioned to aim at the Top/Upstream/BeamLeft GP in the CPA surrounding with the possibly to rotate it from outside. 3
View from Cam-202 before filling. Endwall Beam right Upstream wall field cage and ground plane Beam plug 4
Another photo, and Glenn’s sketch of Francesco’s idea Rotatable tube or other structure Not drawn to scale! PMT TPB Beam right Beam left Beam plug Photo (provided by Heng-Ye) of steel tube 5 intrusion at bldg 182.
More-directional UV detector using SiPM (Jim) TPB-coated Aperture SiPM Tube lined with absorbing baffles. 6
Rotate and tilt on fork with control rods 7
Tiltable mirror design (MicroBooNE paper) Camera and UV pinhole can look down to know well where we’re pointing Mirror 8
Other miscellaneous thoughts so far For deployment: try large “glove bag” to prevent contamination. (Similar idea used ● to prevent KamLAND contamination during camera viewport installation.) Could we put a UV-transparent acrylic dome on Cam-202 tube? Then mount ● pinhole UV detector on conventional ethernet-controlled pan-tilt-zoom (PTZ) camera used as guide cam. Less complicated than mirror? Mirror: “Al+MgF2 is measured to have a specular reflectivity of ∼ 91% at argon ● emission wavelength” -- https://arxiv.org/pdf/physics/0511093.pdf If we really need a 128-nm UV CCD camera, could one take an astronomical CCD ● and coat it with TPB? (Commercial EUV-VUV-xray cameras exist, but all seem to have low QE right where we need it. Also horribly expensive) 9
Pros, cons, and timeliness PMT: Pro: quick, not much R&D needed. Pro: large area, large sensitivity. Con: not ● very directional. SiPM “pinhole camera”: Pro: quick, not much R&D needed. Pro: more directional. ● Con: high directionality requires higher pointing accuracy, more raster scans. Con: small aperture means low flux sensitivity. Visible camera + pinhole UV schemes (mirror or PTZ camera mount): Pro: good ● directionality and pointability, easier to have controlled raster scan. Con: low flux sensitivity. Con: more R&D needed, not quick. Multi-pixel UV camera: Pro: real imaging. Con: lots more R&D needed, could be ● costly. 10
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