Peter-Bernd Otte - 8th March 2010CB collaboration meeting, Mainz

today @DPG

1. New Moeller electronics 1. New Moeller electronics

2. Status of new trigger 2. cellular cluster counter (see Edinburgh talk)

What for?◦ Measure: beam polarity◦ Constituents: tagger, Moeller radiator, electronics◦ essential information for many experiments

Why built it new from scratch? ◦ faster

Used parts:◦ Splitter◦ Trigger◦ TDC (8x)◦ Readout of data

Realised on one FPGA (VUPROM) card◦ One VME CPU to read histograms after

measurement Time to save an event: 20ns Lifetime @ 2nA

◦ 99,999% (with gate)◦ 99% (without Gate)

outputinput

clock

logic cell („modules“):

programmable switches

Interconnection (“cables”):

“has” 1000’s of “modules” and “cables” ~300 I/O signals configuration via software

behaviour of cells and interconnection Not a CPU! Can act as: logic, scaler, TDC, …

New electronic cards arrived (10 cards) „VUPROM 2“ from GSI

◦ FPGA: „Virtex 4“ from Xilinx◦ 224 inputs, 32 outputs, LVDS◦ VMEbus connectivity◦ cheap: 2k€ apiece

TDC programed in FPGA:◦ RMS=30ps

Make use of propagation timetrough smallest entities inside FPGA

startend

How are these TDCs read out?How are these TDCs read out?

“Measure”-FSM1. Wait for 1st hit2. Wait for 2nd hit3. Compute time

differences and save temporally

2 Finite state machines (FSM):• (“Acqu Root on FPGA”)

“Store”-FSM1. Read RAM2. Increase Value by

13. Write RAM

• Each step needs 20ns• FSMs run in parallel

Add more channels without loosing lifetime• One FSM per TDC and per histogram

Detailed view of FPGA

1.8k cells used (9%)

inout

Old New

readout time 20 µs 20ns

lifetime ~50% > 95%

size 1 VME module

measured yesterday:

beam current: 5nA, 30min count asymmetry:

◦ Pfoil not clear yet

)%6(4.3

NN

NNA

N+ N-

improve calibration◦ eliminate ripples

arising from binning

connect more channels◦ Better statistics (@ constant lifetime!)

Possible triggersStatus of hardware

Planned so far:◦ Improved cluster counter

(cellular automata logic)◦ Coplanarity◦ in conjunction with PID:

differentiate charged/uncharged particles for above triggers

◦ Single Tagger signals for detector tests

Include (all) detectors...

Possible to include all detectors◦ All CB crystals (672x 720 cable pairs)◦ All PID stripes (24x)◦ Tagger channels (352x)◦ Endpoint Tagger (~64x)◦ TOF-Panels◦ Inner TAPS crystals (72x)◦ TAPS crystals and vetos (384x)

TAPS electronics has output of all CFD

Trigger modules are available

Moeller electronics working◦ New technique, 106 faster

Trigger◦ Enough inputs: feasible to include signals from all

detectors◦ Coming weeks: Installation of new trigger

electronics in parallel to existing

◦ Help to include TAPS needed