S.MonteilPS COMMISSIONING1 MaPMT-VFE-FE ELECTRONICS COMMISSIONING AND MONITORING. OUTLINE 1)Ma-PMT TEST BENCHES MEASUREMENTS 2)VFE AND FE ELECTRONICS FEATURES 3)MONITORING THE TUBES/VFE/FE SYSTEM IN THE EXPERIMENT. 4)LESSONS FOR COMMISSIONING STRATEGY DATABASE MEETING – JUNE 2007

S.MonteilPS COMMISSIONING2 0) Ma-PMT TEST BENCHES MEASUREMENTS 1)UNIFORMITY OF EACH TUBES : 64 VALUES NORMALIZED TO THE HIGHEST CHANNEL SET TO 1. 2)LINEARITY: DEVIATION TO A PERFECTLY LINEAR TUBE FOR EACH OF THE 64 CHANNELS. 3)SHORT TERM DRIFT : 16 VALUES PER TUBE. 4)CROSS-TALK: 8 ESTIMATORS FOR EACH TUBE. (IN ADDITION WE HAVE 1 MB FILE PER TUBE). 5)HAMAMATSU MEASUREMENTS : SKG, DARK CURRENT, HV AT G=3000….

S.MonteilPS COMMISSIONING3 0) Ma-PMT TEST BENCHES MEASUREMENTS All of these measurements are stored for the time being in an ORACLE- based database developped at lab. Shall be nice to have all of them in the Calorimeter Database. Useful information for Conf. database are : Gain of the channels, which, convoluted w/ the Evgueni’s detector uniformities by cosmics will give the first calibration of the detector. HV of the tubes. PS will use Hamamatsu gain measurement. SPD will use BCN bench measurements. Since both were very close, either solutions are acceptable.

S.MonteilPS COMMISSIONING4 1) TUBES AND VFE ELECTRONICS FEATURES WHAT DOES THIS SYSTEM DO ?

S.MonteilPS COMMISSIONING5 1) TUBES AND VFE ELECTRONICS FEATURES The PS detects signals from 0.1 MIP (a MIP is a typical pion) to 100 MIPS (a high energy electron or gamma) The detector signal is a highly fluctuating light pulse, larger than 50 ns, whose electronics has to cope with. A 64a-PMT device receives the light signal cell (100 tubes for the whole PS). The main issue as far as monitoring is concerned is the non-uniformity of the 64 channels. It has been measured to be less than a factor 2 for most of the tubes. The average charge dynamics is [ ] fc. The VFE electronics samples, integrates and shapes the charge signal of the tube without any dead-time. 16 chips dealing w/ 4 detector channels are set on the board. A jumper can be set to choose a double gain. Dynamics is [1/ ] MIPs.

S.MonteilPS COMMISSIONING6 1) FE ELECTRONICS FEATURES WHAT DOES THIS BOARD DO ? 1.Receives the 64 VFE signals through 16 cables for each of the chips. 2.Digitizes the analog signals 3.Treats the signals and produces a trigger bit in a 8-channels FPGA (AX1000 ) and sends it to DAQ and Trigger path. 4.A dedicated FPGA (APA450) gives to the trigger Validation Board the 2X2 cluster information for PS and SPD trigger bits. Huge connectivity.

S.MonteilPS COMMISSIONING7 1) FE ELECTRONICS FEATURES THE FIRST TREATMENTS AFTER DIGITISATION ARE PERFORMED WITHIN FEPGA: Pedestal subtraction for each half-channel (VFE offsets and FE ADC noise – same order of error magnitude). Pedestal values are parameters to be ECS-loaded and controlled regularly. The preceding 25 ns sample spill-over is subtracted. Governed by the ECS-loadable alpha parameters to be measured for each channel of the detector. The gain of each half-channel is corrected by ECS-loadable parameters. Corrective factor up to 2 can be given. Might handle, if wished, the tube and detector non-uniformities to the price of a loss of dynamics. A trigger bit is generated if the charge value is higher than a given threshold both for SPD (simply transmitted) and PS (typically 10 MIPs)

S.MonteilPS COMMISSIONING8 1) FE ELECTRONICS FEATURES THE TRIGGER PATH : Receives two addresses specifying the maximal cluster of the 2 corresponding 32-channels ECAL boards. Receives addresses and trigger bits from top and right neighbour boards. Computes and sends to the TVB the 2X2 trigger bits of interest for PS and SPD. Computes the SPD multiplicity for the 64-channels Sends the SPD multiplicity to the SPD Control Board. The ECS-loadable parameters are the latencies and phasers between the different electronics systems. Can be determined theoretically. Will be set up in a dedicated commissioning test.

S.MonteilPS COMMISSIONING9 1) SPD ELECTRONICS FEATURES For the SPD, all the calibration is in the adjustment of the trigger threshold in the VFE FPGA. This is completely analog to the correction of the non-uniformities at the level of FE electronics for the PS.

S.MonteilPS COMMISSIONING10 2) MONITORING THE SYSTEM IN DATA TAKING WHAT FOLLOWS IS OUR PREFERRED STRATEGY FOR MONITORING. OTHERS ARE POSSIBLE. PHASE 1 / PEDESTALS) Out of the data, a dedicated run for pedestal computation has to be performed. Values are stored in the parameters database, loaded by ECS and applied to the Board. Since the occupancy of the detector is small (10%), it shall be possible to run offline on data the pedestal measurements. Pedestal measurement is a check of the stability of the electronics.

S.MonteilPS COMMISSIONING11 2) MONITORING THE SYSTEM IN DATA TAKING WHAT FOLLOWS IS OUR PREFERRED STRATEGY FOR MONITORING. OTHERS ARE POSSIBLE. PHASE 2 / MAKE THE DETECTOR UNIFORM) In data taking, we first have to set the Ma-PMT HV value. Starting values at commissioning period WILL BE the Hamamatsu values. Particles at MI are needed for that purpose. Within one tube, we have to identify the channel w/ the largest MIP value and tune the HV such that it gives 10 ADC counts. Then, with this map of uniformity, we adjust the half-channel gain corrective factors such that everybody is at 10 ADC counts.

S.MonteilPS COMMISSIONING12 2) MONITORING THE SYSTEM IN DATA TAKING WHAT FOLLOWS IS OUR PREFERRED STRATEGY FOR MONITORING. OTHERS ARE POSSIBLE. PHASE 3 / CORRECT FOR THE PRECEDING SAMPLE) This is a tricky point. We need to have successive data samples. Hard to recover offline ! Test beams data showed the spread in alpha to be small. Lengthes of fibre bundles are corrected with the chip integration time delay. A dedicated run for PS would be needed. Take several 5 consecutives samples.

S.MonteilPS COMMISSIONING13 2) MONITORING THE SYSTEM IN DATA TAKING WHAT FOLLOWS IS OUR PREFERRED STRATEGY FOR MONITORING. OTHERS ARE POSSIBLE. PHASE 4 / APPLY THE TRIGGER THRESHOLD) Since in this scenario, all the channels are set to 10 ADC counts for MI Particles, the threshold value is the same for everyone. Alternatively, we could imagine to simply correct for half-channel gain differences instead of handling in addition the detector/tube non- uniformities. The clear advantage is that there is no loss of dynamics. The trigger threshold would vary from one channel to the other. The drawback is that the DAQ data shall be properly corrected offline. The virtue of dealing with equal response is that we have a clear and visual way to control the stability of the detector, at least at the beginning.

S.MonteilPS COMMISSIONING14 3) LESSONS FOR THE COMMISSIONING IN THE COMISSIONING PHASE, WE’LL HAVE LEDs AND HOPEFULLY LATER ON BEAM GAS INTERACTIONS WHAT TO DO WITH LEDs ? Nothing for the channel uniformity. Nothing for the alpha determination. Nothing for the trigger threshold. OF COURSE, IT’S VERY USEFUL FOR THE TIME ALIGNMENT AND THE DIAGNOSIS OF DYSFUNCTIONNING CHANNELS.

S.MonteilPS COMMISSIONING15 3) LESSONS FOR THE COMMISSIONING MAKE THE WHOLE CHAIN UNIFORM. FOR THE TIME BEING (ONCE FE BOARDS ARE PRODUCED), WE CAN FEED THE ELECTRONICS CORRECTIVE FACTORS BY MULTIPLYING THE MEASUREMENTS OF THE INDIVIDUAL NON- UNIFORMITY FACTORS WE HAVE SO-FAR : DETECTOR (MODULES AND FIBRE BUNDLES FROM COSMICS STAND RESULTS, INR) TUBES (MaPMT BENCHES, CLERMONT AND BARCELONA). THIS SHALL ENSURE A UNIFORMITY OF EACH DETECTOR WITHIN 20%;

S.MonteilPS COMMISSIONING16 3) LESSONS FOR THE COMMISSIONING NOT ONLY PARAMETERS ARE TO BE FILLED FROM CONFIGURATION DB BUT ALSO THE CONTROL REGISTERS OF ALL THE ASICS AND THE PHASES AND LATENCIES BETWEEN AND FOR ALL CONNECTED SYSTEMS (AS FOR XCAL BOARDS).