STAR Forward GEM Tracker Readout/DAQ Integration

1. STAR Forward GEM Tracker Readout/DAQ Integration G. Visser Indiana University Cyclotron Facility 5/16/2008

2. Modular readout crate architecture backplane Remote regulated DC power ARM ARM ARM ARM ARM ARM ARC ALICE SIU (mezzanine board) Optical fiber to D-RORC 7 pair cable or optical fiber from STAR TCD Signal & Power cables, ≈ 8.3 m, to APV Connector/Motherboards • Two crates, each handles 12 cables, 10 APV’s per cable, a total of 15360 detector channels per crate • ARM (APV Readout Module): 20 ADC channels and data processing FPGA’s (zero suppression, pileup rejection); power for APV on ARM or separate new board (4/crate) • ARC (APV Readout Controller): control FPGA’s, STAR clock/trigger interface and ALICE SIU (data/control link) • Connected by passive backplane, 30 MHz synchronous 24 bit datapath • Uses commercial hardware (6U crate, VME P1 backplane) • Crates mounted on west end ring of STAR magnet, e.g., in former location of SVT crate; magnetic field tolerant design

3. FGT DC Power and Grounding south platform 2nd level readout crate (only 1 shown here) +1.8 V @ 0.90 A, -1.8 V @ 1.56 A +6 V @ 36 A, -6 V @ 22 A APV Motherboard assy. (1 of 24 shown here) 24 m ARM (only 1 shown here) 4x 4AWG 8.3 m Isolated dual DC supply (Wiener PL-508) 3x 20AWG Low-dropout low noise regulator +/-1.25V APV25 ASIC’s Quasi-isolated output +/-1.8V regulator sense lines 4C 18AWG 20AWG FEE GND OPTION JUMPER readout crate backplane GEM bias divider / bypass caps Local loads, not detailed here PREFERRED FEE GND OPTION STAR GND (magnet steel) STAR GND (TPC structure) Non-isolated HV DC supply Inside, at detector HV coax, shown here as two lines for clarity

4. (Stock) Cables from ARM to ACB/AMB • Power & ground, 7C #20 AWG – Belden #5405FE, 5.1mm dia., 56.7 g/m • +1.8 V force • +1.8 V sense • power return “ground” force • ground sense • -1.8 V force • -1.8 V sense • detector ground connection • foil shield w/ #22 AWG drain wire • Control & signal, 18Pair (3 unused) #28 AWG – Alpha #6398 or Belden #9819, 9.8mm dia., estimated 112 g/m • CLK to ACB/AMB • CLK loopback from ACB (arrives at ADC automatically in time w/ signals) • TRG • APV signals to RDO (10 pairs) • I2C SDA/GND • I2C SCLK/GND • foil shield w/ #28 AWG drain wire, and tinned copper braid (rather not have it) • Total cross-section passing last FGT disk: 19.2 cm2 (20 power & 20 signal cables), total mass about 5.5 kg

5. APV analog output driving a long cable In contrast to CMS, we will send the APV analog signals a considerable distance (8.3 m) from the detector, with no buffering or optical conversion at the detector. APV ONLY – NO CABLE – 110 Ω LOAD 19 m PVC CABLE IN/OUT (DOUBLE TERMINATED, AD8129 RECV.) 1 1 10 1 0 1 0 1 0 01 The APV “digital” header provides a convenient test pattern CABLE OUT (DOUBLE TERMINATED, AD8129 RECV., EQ.) Noise level <0.7 mV RMS, i.e., >11.5 bit dynamic range With equalization, full swing is restored, sample-sample crosstalk almost completely cancelled, within 1 sample time (56 ns) Remaining <1% sample-sample crosstalk may be robustly removed with FIR digital filter Works fine, even in this test w/ more than double the planned length (ok we could even consider to allow longer cable if we must… I’d like to know this soon!)