Testing Goals and Notes Sarah Lockwitz, FNAL
Mini-Review Planned for July 28, 2016 • Tentative Charge: • 1. Is the proposed setup and test plan sufficient for evaluating the proposed ProtoDUNE-SP field cage design with regard to high voltage? • 2. Are there any electrical or mechanical problems with the design of the test apparatus? • 3. Are there any safety issues to be addressed? • 4. Does the TSW contain the needed resources to do this? • Tentative Schedule: • 1. Overview and Motivation for the Test (20 min+10) • 2. Plan for ProtoDUNE-SP HV (20+10 min) (Bo or Francesco) • 3. Technical Review: Mechanical Specifications (Jeff) (25+15 min) • 4. Technical Review: Electrical Specifications (Glenn) (25+15 min) • 5. Cryogenics and plan for instrumentation (Alan with input from WM on camera) • 6. Phase II Plans (Cheng-Ju) (20 min) 2
Goals of Testing: Ensure that the ProtoDUNE design is a success • Expose any weaknesses so that we can fix them • Test the high voltage features of the ProtoDUNE design • The beam plug is a challenging feature of the design • Beam plug must be tested in the field cage • There are enough untested features of the field cage that testing everything at once would make it difficult to determine the source of instabilities (if they arise) • Test the field cage without the beam plug first. Characterize performance. • Test the field cage with the beam plug to understand the beam plug performance. 3
Testing Goals & Plans • We cannot do a full size test of ProtoDUNE • We will do a partial & scaled test in 35t. (Size effects?) • Cathode at full voltage (-180 kV), 10 TPC stages at correct voltage, anode plane at -47 kV, resistor chain to ground. • TPC has 4 parallel chains of 5.5 G Ω (11 stages x 500 M Ω . The 500 M Ω is from 2 1 G Ω resistors in parallel between each profile) • Resistors will have surge protection. The last stage beyond the TPC is under development. • Test interfaces. •Really want to evaluate these edges. •First one is at 177 kV •To get that voltage w/o the tail of resistors, one really gets into large tube to tube Δ Vs (~20 kV) 147 153 162 171 180 171 162 153 147 4
Let’s think about this…it would be good to have an What is a successful test? answer by the review • We want the HV+TPC design to not adversely affect data-taking at ProtoDUNE • TPC should be robust (no breakage of field cage from HV) • We shouldn’t have instabilities that affect data-taking • HV system should not create troublesome noise for the DAQ (filter can be tested separately)* • System should not create light that adversely affects data-taking • Have not found this to be an issue in a non-broken TPC • Might want to put a PMT in the cryostat • Should not have freq. breakdowns (relative term, aim for zero). 5
Rough Schedule • July: • Clean pieces • Complete design of field cage components • September: Install PhaseI HV Test including TPC circuit (resistors & varistors) • October: Purge, cool down & fill cryostat • Order long lead time materials • November: Perform Test • Mini-Review week of July 25th • December: Transfer LAr to LAPD. Warm up cryostat. • Fabricate parts Takes a little over 1 month • August: • January: Install Phase II • Remove 35t TPC • February: Purge cooldown & fill • Continue fabrication • March: Test Phase II • Test fit? 6
Blips: Toroid and FCT signals while running Do not cause trips • Monitoring Ideas Can affect data-taking (shield plane reduces this) • 35t and another experiment have seen them • Both positive & negative polarities • • Toroid: Polarity of first pulse tells you where the Small test stand has not. • voltage drop was Not a deal breaker at this time, but something to be aware of. • Pick off/Field cage termination (required port) • HV Supply: Heinzinger offers much better current readout ability (~100 nA vs 10s uA with a Glassman) • Camera: M. Kordosky & group (required window(s) and/or feedthrough ports) • PMT/SiPMs? (required ports) • Any other ports needed? • Not planned at the moment: Antenna, microphones 7
Membrane Performance? • The proposed test does not evaluate the effect of the TPC+cryostat membrane performance. This should be a low risk (40 cm away). • The 35t was done by a Japanese company and has a different profile than what Proto-DUNE will have (GTT). • We have some GTT profile onsite. We have some that people are willing to allow us to test. • If there’s a strong motivation, we can test them in a small test vessel we have onsite with access to TPC-quality argon. Would only be able to test up to ~100 kV at the moment (likely < 1 inch). We would have to pay for the argon. 8
A Note on Cable Terminations • I saw Bo has requested DS 2134 cable. • I am sure people already have ideas about cable terminations. • If anyone would like an additional idea, we’ve used this technique for cable terminations at FNAL. Tevatron used them for decades. • I’m willing to share parts, help with drawings, etc. if anyone wants to use this. 9
Cleaning G10/FR4 • An option for cleaning the G10/FR4 parts is an ultrasonic bath the TD at From T. Strauss FNAL has • The parts in the photo are ~2.5 m in length • On the G10, the cleaner used was Elba-Clean 65 (total cost to arrive at the lab was ~$1k) • If there’s interest, I can ask if this is available to use at the end of the summer. 10
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