1. PMT cabling Gian Luca Raselli INFN Pavia
WA104 meeting 14 September 2017

2. PMT installation layout
The new light collection system consists of 360 PMTs 8‘’ HAMAMATSU R5912-MOD. Behind each wire chamber, 90 PMTs find place according to the proposed geometry which allows the detection of interacting events down to less than 100 MeV deposited energy.

3. Cable distribution
For each T300, cables and fibers are grouped 10 by 10, according to the following deployment scheme which uses the 36 central chimneys of each TPC:
PMT signal cables and optical fibers make use of the same chimneys, 9+9 for each TPC.
HV cables are distributed along the remaining 9+9 chimneys.
Signal cables + Optical fibers
HV cables

4. Available ports for feed-through flanges
PMT signal and HV feed-throughs can be placed on the DN100CF ports available on the top of the chimneys. PMT optical feed- throughs can exploit some of the remaining DN200CF flanges.
DN200CF
DN100CF

5. HV distribution
Each PMT requires a power supply of about 1500V to get a gain of about 107. This will be provided independently for each device, using an external HV system (the same adopted at LNGS):
Two power suppliers Bertan R, for the generation of the primary HV (2000 V);
8 x CAEN A1932 (4 boards per T300) for the HV regulation and distribution;
8 x R648 units to adapt the output RADIAL 48 ch. connectors to SHV standard.
HV flanges and HV system will be connected by means of 360 SHV-SHV cables (+40 spares).
11 (10+1 spare)

6. PMT HV racks PMT HV system can be assembled in two racks.
2 BERTAN R HV power supply;
2 CAEN SY1527 crates;
8 A1932 distributors;
8 CAEN R648 Radial-to-SHV adapters;
Ancillary devices for network and slow control.

7. PMT HV cable deployment
HV rack are assembled on the mezzanine.
All the HV cables (400 HV, SHV-SHV cables) are grouped in bunches of 11 cables (10 cables + 1 spare).
Length ~ 25-30m.
PMT HV Rack(s)
MEZZANINE
Radial-SHV adapters
PMT HV cables
(Bunches of 11 cables)
TOP

8. PMT DAQ racks
PMT electronics are assembled in 4 racks, positioned on the mezzanine.
8 VME Crates hosting 3 V1730B each (LNGS old stock).
24 CAEN V1730B digitizers;
BNC-MCX adapters + ancillary devices.
All the cables (400 RG58/U, BNC-BNC) are grouped in bunches of 11 (10+1 spare) cables. Length ~ 25-30m.
~360 BNC-MCX adapters are needed for interconnection.

9. Summary
For HV we need 36 bunches of 11 (10+1 spare) cables SHV- SHV, RG58 (red color) ~25-30m length.
For PMT signal we need 36 bunches of 11 (10+1 spare) cables BNC-BNC, RG58 (red color) ~25-30m length.
In addition ~360 BNC – MCX adapters.
We are considering to buy the cables in US. Linda is asking an offer to local vendors.

10. Mounting on the TOP/Mezzanine
For the cabling/fiber deployment it is important to define the available space on the detector TOP and on the mezzanine, together with the access points and interconnection passages.