Update on PMMA cathode developments Status Mechanical - electrical - PowerPoint PPT Presentation

Update on PMMA cathode developments Status • Mechanical - electrical - optical - operation in TPC mode — successfully tested • Basic double sided ITO coated units of up to 1x1m 2 feasible • Large evaporator for TPB built and commissioned @ CERN • A prototype ITO/PMMA cathode (ton scale LAr TPC) long term test ongoing News • Cool-down for spring loaded contact test to the ITO surface successful • ITO coating quality issue (under investigation with Visiontek) • Progress on the conceptual design WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ

Cathode for ton scale LAr TPC (ArDM) — tests at CERN Aims • Mechanical robustness during T variation • Contact and electrical resistances • Contact failures WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 2

Getting experience with the mechanics - the components Cathode plate Mechanical structure Electrical contact by spring washers and bolts WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 3

Arrangement of T-sensors and test contacts to the ITO surface Spring loaded contacts (CuBe washer) Elastic at low T Non-sparking Tsens upper Surface 11 12 1 Tsens lower Surface 2 10 CuBe washer 9 3 4 8 ITO PMMA Plate 5 7 CuBe washer 6 Plastic Copper Screw Wire WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 4

Test cycle At T LAr Lifting the plate, LAr evaporating Cool down, warm up overnight immersing in Lar WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 5

Open cryostat tests at CERN — ETHZ laboratory Electrical connections to 12 points on lower ITO surface Temperature sensors LAr bath WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 6

Preliminary results Resistance V.S. Temperature Resistance V.S. Temperature 2000 400 1500 1000 300 500 0 -200 -150 -100 -50 0 200 100 At low temperature (87 K), two rings (point 2 and 9) lost contact, (resistances are out of the range) 0 -120 -88 -55 -23 10 Other resistances look reasonable (not measures with 4-wire method) Contact problem related to mechanical imperfection of holes (not related to ice formation) WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 7

ITO coating problems Appeared only on 2 surfaces out of 6 Presently under investigation with Visiontek WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 8

Conceptual design Plate / PMT units ITO/TPB coating lattice spacing: 0.5 … 1m Resistive connections Resistive connections ITO coating PMT array WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 9

Possible arrangement in WA105 PMT and Cathode structures ITO coated PMMA Plates installed at the Cathode WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 10

Summary / next steps Summary • Basic R&D finished • Company identified capable to provide ITO coatings up to 1 x 1 m 2 • Quality issues to be understood (process) — need to develop QA procedure • Conceptual design more or less existing Plans • Continue tests in the 3L cell • Long term tests ongoing • Developing the mechanical design (ongoing with Adamo) WA105 Technical Board meeting 29.6.2016 C.Regenfus ETHZ 11