EIC Tracking R&D Meetings: Mondays 9:00am - 11:00pm
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Link to the previous meeting: https://wiki.bnl.gov/eic/index.php/RD-2018-02-12
Link to all previous meetings: https://wiki.bnl.gov/eic/index.php/Eic-rd-meeting
Kondo (chair); Klaus, Marcus, Matt, Silvia, Tom
Progress at BNL
- BNL crew at Fermilab for preparation for the Test Beam
Progress at FIT (Marcus)
- Hardware: Just acquire longer screws needed the compensate the non uniformity of the carbon fiber frames to tighten to the pull outs to stretch the foil. First attempt with shorter screws suspected to be one of the reason for the gas leak observed with the mock up chamber
- Software: Matt (Bomberger) has made good progress in getting familiar with eicRoot and run start basic simulation and produce generic plots like resolution (residual of reconstructed vs. simulated etc ...) Produce a first internal report too early to share.
Progress at INFN Trieste (Silvia)
- Small pad readout: Prototype working as expected, Preliminary measurement shows non uniform gain with the micromegas amplification. But this is likely caused by a minor problem under investigation by the team. Expected a Master thesis on this R&D work in the coming weeks
- Novel photo cathode material: Silvia's team went to Bari with 3 fully characterized Thick GEM samples.
The 3 samples have been coated with the nano diamond (ND) layer at Bari and brought back to Trieste. Plan to characterized again the samples, study the performances such as the gain distribution, robustness & stability of the ND layer deposition.
Progress at SBU (Klaus)
- Indirectly related to EIC R&D work: The group has been preparing the sPHENIX TPC prototype for test beam at FNAL.
- The prototype will be move and installed to FNAL FTBF on March 15th-17th. The prototype of the same size of the inner field cage of sPHENIX with a 10 cm x 10 cm GEM readout
Progress at UVa (Kondo)
- Hardware: Design of the low cost GEM support frames completed and production at UVa machine shop has started. Expected to have the frames ready this week and start the gluing next week.
- Simulation: UVa grad. student Siyu is no longer going to be involved in eicRoot simulation work. He has a lot of other duties that will keep him busy and unable to dedicate time to it. We are looking for a replacement for him
Progress at Temple U. (Matt)
- Recently built FGT design based Triple GEM prototype with Kapton ring as spacers died after a week of cosmic data taking. The prototype together with the second prototype built with standard straight spacers had, from the start a leakage current through the divider significantly higher than the expected value. Matt report that after the dead Kapton ring chamber was removed from the cosmic stand and tested, they found out that all the HV sectors were drawing a very higher current than the expected 1 nA One source of the problem can be that the foil used to assembled the prototype were Tech Etch GEM foil, but this has not yet been clearly demonstrated. The group is investigating the problem and stopped for now the testing of the second prototype with straight spacers.
- Marcus ask about which layer was located the displaced kapton ring in the small 10 cm x 10 cm prototype tested in x-ray test beam by Bob. x-ray imaging shows a bigger efficiency drop around this single displaced kapton ring than the accumulated drop in the 3 stacked ring in the center of the chamber suggesting than the impact of efficiency drop due to presence of spacers is not of the same amplitude in different layers of a Triple-GEM detector. Klaus seems to remember that Bob mentioned that the displaced kapton ring occurs in the induction region of the chamber => we need confirmation from Bob on that issue. Matt confirm that that the Kapton ring wall are 125 microns thick, which shows that the efficiency drop is more far sensitive to the dielectric property of the material modifying locally the electric field because of the charging up of the dielectric than the thickness of the of the spacers, which would also explain why the loss is far more severe in the induction region where the charging up is more pronounced due to the 3rd amplification than elsewhere in the GEM chamber
- Tom shares a picture of a 3D printed frames with 200 micron spacer that his group just developed for the sPHENIX GEM readout prototype. The 3D printed frame material is TLA and concern about outgassing is raised by Klaus. One solution to prevent outgassing would be to coat the frames with the same varnish used for SBS GEM chambers and CMS GEM frames. Tom obtains information about the varnish (NUVOVERN) from Kondo but find the manual painting of the frames tedious specially in the context of mass production frames. Marcus mentioned the approach adopted by CMS with a spray technique for the coating. This solution is faster and ensure an uniform coating. Silvia share her recipe with "cooking" fiberglass material used for thick GEM (heating in oven at 180 degree for a couple hours) to cure or at least drastically reduce outgassing. However this approach would not work for most o the materials (plastics) used for 3D printing because of the high temperature. Marcus is planning to test ABS plastics (another 3D printing material) in the CMS GEM aging test facility at CERN for radiation tolerance and aging.
- Tom provide a couple of links (see below) relevant to the discussion about 3D printing technologies with comments Some papers on 3D printed parts outgassing:
Tom comment: Tests less common materials: polyamide, glass, acrylic, and sterling silver...concludes for ultra high vacuum that only silver is OK".
Tom comment: Concern that plastic printing technique (most all parts are hollow) creates long term virtual leaks. Concludes: " At room temperature the RGA showed no measurable increase in the background signals and the overall base pressure did not increase, indicating that any outgassing from the plastic was insignificant at these moderate pressures regardless of the infill percentage. Our assumption is that the printed parts are porous enough that any trapped air volume is rapidly evacuated from the interior of the part and the vapor pressure of the plastic was small."
Tom comment: This one notes that NASA has updated their database to include both ABS and PLA. The results for both materials are encouraging!!! They worry about virtual leaks
- Marcus ask Tom and Klaus if they would be willing to join eRD3-eRD6 Tracking effort to submit a proposal for 3D printing GEM frames development at the next EIC R&D funding cycle. Tom and Klaus seems enthusiastic about the idea. Klaus mentioned ongoing R&D effort at CERN RD51 for 3D printing and related development with the ultimate goal of 3D printing of MPGD prototype for R&D
- Silvia report on the R&D on Experimental Technologies of the CERN EP Department to shape CERN detectors R&D program for the period of 2020 - 2025. The effort is aimed at providing some input for the future particle physics ex[experiment in Europe but is also oriented outside CERN and look for synergies with the international HEP and NP communities need.
- Working group WG2 of this R&D plan concerns Gaseous Detector Technologies, which is relevant for our activities. There was a first meeting involving mostly CERN affiliated speakers.
- A second WG2 meeting held today with a broader audience and participants and 20 short contributions (see https://indico.cern.ch/event/702148/) on MPGD technologies relevant to the RD51 communities as well as couple of other talks on associated technologies such as RPCs or Electronics.
- A third meeting is scheduled in March with a 45 min report about the outcome of the discussion with the community followed by a more comprehensive meeting sometime in 2019 to discuss the way forward