CMS WeekDec 2002E. Hazen HF Electronics Status Report E. Hazen, J. Rohlf, E. Machado Boston University.
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CMS WeekDec 2002E. Hazen HF Electronics Status Report E. Hazen, J. Rohlf, E. Machado Boston University
CMS WeekDec 2002E. Hazen HF Electronics Installation Preliminary HF Readout Boxes 24 PMTs each Cable Route ~5m through shielding Electronics Housed in standard racks (3U card cages)
CMS WeekDec 2002E. Hazen HF QIE Crate Proposal QIE Board 6 Channels 4 Boards = 1 PMT box Clock and Control Module (3 boards) Standard 3U subrack (custom backplane) ROB 1ROB 2ROB 3ROB 4CCM Typically only 3 of 4 ROBs used Calibration module can occupy unused ROB site (up to 5 slots - 10cm)
CMS WeekDec 2002E. Hazen PMT Base PCB Base Supports 8 PMTs with HV distribution Rear detail showing dual coax (signal plus reference) for each PMT This is fine for current testing but should probably change to a solder termination for production.
CMS WeekDec 2002E. Hazen PMT to QIE connection Preliminary PMT Anode 93Ω coax 100Ω pair (or multi-coax) Coax shield ground at each PMT base Overall shield connected to QIE ground Separate Ground for each PMT QIE Signal Input QIE Reference Input PMT Box Two pairs per PMT channel Multi-pin shielded connectors
CMS WeekDec 2002E. Hazen PMT Box Patch Panel MDR-36 Connector Site Mini-coax compatible with existing PMT boards We plan to make a small PCB which connects 6 PMTs to one multi-pin connector. These can be retro-fitted to existing PMT boxes for the test beam. The final box could use a similar PCB or a larger one which would handle 24 PMTs.
CMS WeekDec 2002E. Hazen HF QIE Digitizer Board Change to 36 pin MDR Connector (12 pairs, each with GND) Optical Outputs change to Honeywell ST connector VCSEL (but still near rear) Electrically identical to HCAL version 3U Eurocard form factor
CMS WeekDec 2002E. Hazen Amphenol Skew-Clear TM Cable ● High-performance, compact ● Available in zero-halogen version (ATLAS, CMS) ● Terminates to convenient Mini-D connectors with overall metal shell
CMS WeekDec 2002E. Hazen Skew-Clear Cable Drawing Will supply zero-halogen version on request OD = 10mm (28AWG) or 12mm (24AWG)
CMS WeekDec 2002E. Hazen MDR Connector Proposed Pinout RefSignal Ref Return Signal Return Shield 12-pair Skew-Clear cable handles 6 QIE channels Each channel has: Pair 1: Signal, Signal Return, Shield Pair 2: Reference, Reference Return, Shield Overall Shield connected to metal connector backshell
CMS WeekDec 2002E. Hazen Coax Cable Noise vs Length
CMS WeekDec 2002E. Hazen Skew-Clear Cable Noise vs Length Scatter due to inconsistent results (probably a bad connection)
CMS WeekDec 2002E. Hazen HF Noise Test Summary ● PMT Test setup comissioned with QIE/HTR/DCC chain. ● Extensive testing done with two cable types, lengths from 1-6m: – Dual RG-174 coax with overall braid shield – Amphenol Skew-Clear(tm) 100Ω shielded pair ● Noise performance is excellent: – 9500e rms (1.5fC) for 6m skew-clear cable – 12500e rms (2.0fC) for 6m RG-174 coax cable (single pe is 8fC for PMT gain of 5E4)
CMS WeekDec 2002E. Hazen PMT Pulse Examples fC ~ 125 pe PMT pulsed using Nichia blue LED and avalanche pulser Coupled through 2m RG-174 coax QIE Samples (30ns each) ~ 35 pe
CMS WeekDec 2002E. Hazen Cable Matching Issues ● Problems with impedance matching: – RG-174 coax okay, but overall braid lowers impedance --> reflections – Paired cable (like skew-clear) is 100 ohm differential impedance only... single-ended impedance to ground is lower... not well matched to high-impedance setting of QIE. ● 93 ohm ribbon coax may be the best choice
CMS WeekDec 2002E. Hazen HF Front-End Status Summary
CMS WeekDec 2002E. Hazen Critical Issues for FE ● Cable / Connector: – Pair vs coax issue still open: must settle ASAP so new QIE prototype can proceed. Need proper PCBs to make meaningful measurements of dispersion, crosstalk. – ROBOX design follows: PMT board, patch panel. ● Crate issues: – Backplane design – Power & Cooling ● LVPS – How best to utilize 'common LV' scheme without compromising performance
CMS WeekDec 2002E. Hazen Web Page for HF Front-End http://ohm.bu.edu/~emachado/HF New web page with cable/connector documentation. Will be expanded as more documents become available...
CMS WeekDec 2002E. Hazen HF Electronics Meeting Proposal ● Start with video conferences ● Follow up with 'workshop' style meeting at Boston or Fermilab (late Jan or early Feb)