1. Status of the PMT light detection system Gian Luca Raselli 20-AUG-2015 ICARUS executive meeting

2. ● The present T600 light detection system will be refurbished with new 8” HAMAMATSU R5912-MOD PMTs. ● Given the present TPC mechanical structure, the layout allows a PMT deployment of 90 devices behind each chamber (a total of 360 PMT in the whole T600 detector). ● This design yields a 5% photocathode coverage of the wire plane area. ● The number of photoelectrons collected per MeV of deposited energy in a single TPC is ≈ 5 phe/MeV, allowing the possibility to trigger low energy events (100 MeV) with fairly high threshold and multiplicity. PMT deployment Slide: 220-AUG-2015 - ICARUS executive meeting Z axis (beam direction) X axis (vertical direction)

3. PMT procurement The PMT order has been sent to Hamamatsu in August 2015. The supply of 400 samples is organized in two parts: 1)a pre-series (20 samples), expected delivery in the second half of September 2015; 2)a series production (380 samples), expected delivery from October 2015, about 100 samples/month. All PMT delivered shall be compliant with the technical requirements reported in the IT-4126/DG-DI/WA104 Tender Form, which specify all the deliverables included in the supply and their technical details. Slide: 320-AUG-2015 - ICARUS executive meeting

4. Acceptance conditions Upon delivery the units will be verified if they conforms to the technical requirements. a)For the pre-series units all the 20 PMTs will be tested at warm and at cryogenic temperature. b)For the series production, all the PMTs will be tested at warm temperature, 10% of each batch will be verified in LAr. In case of a deviation of ±10% with respect to one or more of the parameters specified: a)The pre-series will be rejected by CERN and the contractor shall deliver new pre-series units within six weeks at no additional cost to CERN, subject to verification by CERN; b)The number of units to be verified will be increased to 20%. In case the additional 10% of quantity verified is not conform to the parameters specified the entire batch will be rejected by CERN. In such a case the contractor shall deliver a new batch within six weeks at no extra cost for CERN. Slide: 420-AUG-2015 - ICARUS executive meeting

5. Areas for PMT activities The main activities for PMT tests, certification, instrumentation and preparation for the final installation will be organized in three different areas at CERN: 1) Warm tests at IdeaSquare building (B3179); 2) Cold tests at building 182; 3) TPB deposition at TE-Laboratory hall (B169). All these areas are being instrumented in order to be ready as soon as the first PMT batches (20 samples) will be delivered. Some complementary measurements (for ex. photo-cathode Quantum Efficiency, TPB deposition certification, Transit Time Spread…) will be carried out in other properly instrumented laboratories. Slide: 520-AUG-2015 - ICARUS executive meeting

6. Test area 1 (warm tests) Preparation of an area for PMT warm tests is in progress in the IdeaSquare building (B3179) and it will be completed during the first half of September. A set of optical fibers and cables will connect up to 16 samples under test placed in a dark room to the electronics and optical equipment installed in an adjacent site. Slide: 6 Main planned activities: PMT bases mounting; Functionality check for a few days in dark environment; Single electron response (peak- to-valley ratio and pulse shape); Gain response vs. power supply; Dark count rate; Pulse linearity; … 20-AUG-2015 - ICARUS executive meeting

7. Test area 2 (cryogenic tests) Preparation for the cryogenic tests in B182 is progressing. All materials have been ordered and most of them are already available. The dewar for the tests will become available at the end of September. Slide: 7 Planned activities: Functionality check for working at LAr temperature; Operation stability at cryogenic temperature by measuring the gain response for few days. 20-AUG-2015 - ICARUS executive meeting

8. Test area 3 (TPB evaporation) Slide: 8 Laboratory tests for the definition of the evaporation procedures (temperature, duration, required compound quantity, TPB coating quality,…) have been already started in Pavia with a local device and will continue at CERN. 20-AUG-2015 - ICARUS executive meeting TPB evaporation will be carried out in the B169 “TE-Laboratory hall”. The area will become available the first week of September. Transport of the evaporator and related equipment has already been organized.

9. PMT bases The production of bases for R5912 PMTs is progressing. All the passive components have been ordered and are available for mounting. Printed circuits have been ordered and few prototypes have been checked. The component mounting for 50 samples will be completed the first week of September. Slide: 920-AUG-2015 - ICARUS executive meeting

10. Conclusions Slide: 10 ● The PMT procurement and test organization at CERN are well proceeding. ● Other ancillary activities, in particular material supply (cables, TPC compound, optical fibers…) and design of the supports for the final mounting, are going on. ● The upgrade of the light detection system is progressing according to the planned time schedule. 20-AUG-2015 - ICARUS executive meeting