Preliminary Results of the Beetle Readout for the MaPMTs  Part 1: as presented on  Achievements since last LHCb week  Common Mode correction  Light scan  High Voltage scan  Conclusion  Part 2: new results  Calibration  Measured all connected MaPMT pixels  Preliminary analysis of spectra  Conclusions MaPMT workshop, IC, Stephan Eisenhardt University of Edinburgh J. Bibby, S. Eisenhardt, F. Muheim, N. Smale

2 MaPMT workshop, IC, Stephan Eisenhardt Achievements since last LHCb week o o New Beetle chip è èvisible noise factor 2-3 lower compared to the old chip which had died (another sign that the old chip was dodgy…) o o Tuning of existing setup: è ènoise reduction of factor ~2 o o Noise reduction session: (2 1/2 days together with John and Nigel) – –rerouting of power supplies!! – –shielding of LED pulser! – –new coax cables between MaPMT and HD board!!!! – –new GND routing layout for unused channels at PMT base!!!! – –new star point for GND at front-end!!!! – –massive (1/2 inch) Al GND plate below HD mother board!!! è èall-in-all a noise reduction of factor ~5 o o Common mode reduction: – –problem: 12 connected channels move more than the others – –solution: split into different groups and treat independently è ènoise reduction of factor ~3 – –problem: individual channels have ~10% weight  artificial dip at cut position in corrected spectrum – –solution: iterative CM reduction  dip reduced and moved to pedestal, CM reduction stays efficient

3 MaPMT workshop, IC, Stephan Eisenhardt Data Frame from Ntuple o FED takes 160 samples / event o header samples: –show double peak –also visible on oscilloscope èstructure comes from the front-end of the system o 12 channels bonded –1 analog TestOut –1 outside the sampled frame due to mismatch in timing è10 channels visible o bent base line –Beetle1.2 ‘feature’ –signal inverted for better match to FED ègives positive charge signals 128  1 data frame header bits:  200mV bonded channel w/o CM correction

4 MaPMT workshop, IC, Stephan Eisenhardt Signal w/o CM correction o Uncorrected pedestal width:  ~ 4.5 ADC o Double peak structure variable with runs (two peaks, shoulder or broader flank)  ~ 2 pedestal run signal run

5 MaPMT workshop, IC, Stephan Eisenhardt Signal with CM correction o Uncorrected pedestal width:  ~ 4.5 ADC o Corrected pedestal width:  ~ 1.4 ADC o artificial dip in spectrum from CM correction on few channels  ~ 2 w/o CM correction with CM correction

6 MaPMT workshop, IC, Stephan Eisenhardt w/o CM correction with CM correction LED Light scan o Varied amount of light to determine a working point with:  ~ 1 80% signal65% 20%38%  ~ 2  ~ 1.5  < 1  ~ 1

7 MaPMT workshop, IC, Stephan Eisenhardt w/o CM correctionwith CM correction HV scan I - corner pixel o HV: -750…-825V o Uncorrected pedestal width:  ~ 4.5 ADC o Corrected pedestal width:  ~ 1.4 ADC o clear single photon signal 750V775V 825V800V

8 MaPMT workshop, IC, Stephan Eisenhardt w/o CM correctionwith CM correction HV scan II - corner pixel o HV: -850…-925V o Uncorrected pedestal width:  ~ 4.5 ADC o Corrected pedestal width:  ~ 1.4 ADC o clear single photon signal 850V875V 925V900V

9 MaPMT workshop, IC, Stephan Eisenhardt w/o CM correctionwith CM correction HV scan - center pixel o HV: -750…-900V o this pixel has a significantly higher gain 750V800V 900V850V

10 MaPMT workshop, IC, Stephan Eisenhardt Things to do: o calibration of signaldone o proper S/N calculationdone o straighten out shifts in timingdone o check LED pulse width with analog TestOut channelnot done o get proper BoardBeetledue to be submitted o the whole issue about digital readout is not yet touched...still

11 MaPMT workshop, IC, Stephan Eisenhardt Part 1: Conclusions o Great progress since last LHCb week –level of noise using the HD board is down by 2 orders of magnitude –setup much better understood –this knowledge is put into the design of the BoardBeetle –analog readout of 8-stage MaPMT with Beetle1.2 is possible –proper S/N figure still to be determined o Binary readout option (no CM correction) still to be evaluated with BoardBeetle o Readout of 12-stage MaPMT with Beetle1.2MA0 (Nigel) looks very promising as well  report at MaPMT workshop o a great ‘Thank you!’ to John and Nigel!

12 MaPMT workshop, IC, Stephan Eisenhardt Beetle Readout Calibration o Voltage step: 0.0V,0.5V,…5.0V,5.5 o Error:  0.025V…  0.2V o Rise time: <10ns o Ringing: within 25ns o Attenuation: 400  10 o C eff : 3.0  0.1pC o 1V: Q = CV = 47  2.3 ke - = ~150mV è 1 photoelectron o Linear description up to 2.5V (2.5 photons) o Quadratic description beyond Polynom fit to peak positions 12 runs with varied voltage step individual Gauss fits no CM correction!

13 MaPMT workshop, IC, Stephan Eisenhardt Signal in Low Gain Pixel o Poisson fit: o No photo conversion at 1 st dynode included o Shoulder not described è Gain underestimated o = V (850V): o Gain = 26 (37) o Noise = 1.2 (1.2) o S/N = 22 (31) o K 1 = 3.5 (3.4) o Signal loss: ~13% (~10%)

14 MaPMT workshop, IC, Stephan Eisenhardt Signal in High Gain Pixel o Poisson fit: o No photo conversion at 1 st dynode included o Shoulder not described è Gain underestimated o = V (850V): o Gain = 51 (78) o Noise = 1.6 (1.6) o S/N = 33 (50) o K 1 = 3.5 (4.6) o Signal loss: ~9% (~7%)

15 MaPMT workshop, IC, Stephan Eisenhardt Noise Status o where are we: –CM correction gives factor of ~3 reduction –then we get a pedestal width of 1…1.5ADC channels –calibration gives a noise level of 2000…3000 e - èthat is a factor 2…3 larger than what we expect for a channel with 10pF o where can we get with BoardBeetle: –track lengths 25…75mm (instead of ~175mm + two connectors) –all channels connected (no bricolage to care about unused channels) –less antennas –low impedance ground –lower capacity –great care taken to avoid noise brought in from the outside (e.g. via supplies, grounds or fast control) èwith that there is reasonable hope to get a noise level of O(1000 e - ) without CM correction

16 MaPMT workshop, IC, Stephan Eisenhardt Room for Improvement o with the HD system: –Improve fits –Try to understand shoulder (real photo conversion at dynode??) –Comparison with Beetle1.2MA0 and 12-stage MaPMT –Trial run of Binary operation (noise still a factor of 3…6 too high) o with the BoardBeetle: –Improved noise situation –Full MaPMT readout –Serious evaluation of binary readout –Test beam

17 MaPMT workshop, IC, Stephan Eisenhardt Things to do: o study LED pulse behaviour through analog TestOut channel o get proper BoardBeetle, cabeling and jigs and get it operational o compare results from HD board to BoardBeetle to see what we gained o compare Beetle1.2(8-dyn) and Beetle1.2(12-dyn) o get through the learning curve of the digital readout

18 MaPMT workshop, IC, Stephan Eisenhardt Part 2: Conclusions o Calibration: linear up to 2.5 photons, quadratic behaviour beyond 150mV/47ke - or 26ADC/47ke - o Noise level: 2000…3000 e - o Still room for improvement and reason to get it with BoardBeetle o Present Poisson fit underestimates gain: but we already get: Gain: 26…51ADC S/N: 22…33 Signal loss: 13…9% Gain: 37…78ADC S/N: 31…50 Signal loss: 10…7% o That already looks very nice! o This promises to get an exciting test beam! o Do I have to mention that there still is lots of work to be done?