Werner Riegler CERN, November 2003 CARIOCA Werner Riegler, CERN November 24 th, 2003, LHCb week Discussion of the final Prototype results Plans for CARIOCA.
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Werner Riegler CERN, November 2003 CARIOCA Werner Riegler, CERN November 24 th, 2003, LHCb week Discussion of the final Prototype results Plans for CARIOCA / ASDQ decision
Werner Riegler CERN, November 2003 CARIOCA TDR: ASDQ is our baseline solution CARIOCA is our preferred solution caveat: we cannot afford ASDQ the
Werner Riegler CERN, November 2003 CARIOCA CARIOCA is a responsibility of the CERN LHCb muon group. Francis Anghinolfi and Pierre Jarron are our ‘advisors’ from the MIC group.
Werner Riegler CERN, November 2003 CARIOCA Block Diagram Signal tail cancellation 2x pole/zero, t0=1.5ns, topology from ASDQ Preamp tail cancellation 1x pole/zero, topology from ATLAS MDT Topology from ATLAS MDT PreampLVDS, standard cell topology from ATLAS MDT prototype
Werner Riegler CERN, November 2003 Manpower Walter continues in Cagliari
CARIOCA We had a very useful review in February We got very useful suggestions in order to increase stability (coupling). Francis Anghinolfi got involved in order to help us ironing out some of the problems in the preamp.
Werner Riegler CERN, November 2003 CARIOCA10 We received CARIOCA10 on September 15 th. Test board designed by Davide (Cagliari) and produced at CERN. 17 CARIOCA boards were equipped 34 chips. Tests were started October 1 st. All test results can be found on http://home.cern.ch/riegler
Werner Riegler CERN, November 2003 CARIOCA10 8 channels pos/neg switch Test pulse even/odd 8 individual thresholds Can be switched to a single threshold Analog output of channel 8
Werner Riegler CERN, November 2003CARIOCA10 3x4mm chip 82 pins 25 pins on each side
Werner Riegler CERN, November 2003 CARIOCA10 Traditionally one does extensive LAB tests before putting the chip on the chamber. Because our last testbeam period in T11 was October 22 nd to Nov 11 th, lab test are not yet finished … There is no way we could have advanced further up to now … CARIOCA10 was tested on M3R3 (4boards), GEM (6 boards) and we fully equipped a CERN M3R1 chamber. We found a nice way for high rate tests in GIF without having beam – this is also ongoing. Results are preliminary
Werner Riegler CERN, November 2003 CARIOCA10 test board We wanted the results quickly, we don’t have the final package We did an ‘optimum’ and ‘worst case’ package: Optimum Package (‘no package’): Chip bulk is glued to the board gound with conductive Epoxi, Wire bonds are very short Worst Case Package: Chip bulk is insulated from the board gound Wire bonds are very long
Werner Riegler CERN, November 2003 Sensitivity (discriminator) On CARIOCA10, sensitivity was doubled in order to decrease minumum detectable charge (4fC 2fC) for GEM application. Maximum threshold is 300mV (limited by discriminator). Sensitivity decreases by factor 2 from 0 to 220pF.
Werner Riegler CERN, November 2003 Sensitivity variations Channel to channel variations are smaller than chip to chip variations
Werner Riegler CERN, November 2003 Sensitivity Variations, 0pF Pos: 16.0mV/fC, 0.56mV/fC r.m.s, i.e. 3.54%. Pos: 14.5mV/fC, 0.62mV/fC r.m.s, i.e. 4.31% ‘package’ causes a decrease of 9% Neg: 14.7mV/fC, 0.56mV/fC r.m.s., i.e. 3.8% Neg: 13.1mV/fC, 0.56mV/fC i.e. 4.3% ‘package’ causes a decrease of 11%.
Werner Riegler CERN, November 2003 Sensitivity Variations,0pF Subtracting average per chip and scaling by Sqrt(8/7) Pos: 16.0mV/fC, 0.34mV/fC r.m.s, i.e. 2.15%. Pos: 14.5mV/fC, 0.34mV/fC r.m.s, i.e. 2.36% Neg: 14.7mV/fC, 0.40mV/fC r.m.s., i.e. 2.7% Neg: 13.1mV/fC, 0.26mV/fC i.e. 2.0%
Werner Riegler CERN, November 2003 Sensitivity Variations Sensitivity is 16(14.7) mV/fC for the positive (negative) amplifier. Sensitivity variations are <5% r.m.s. The DIALOG DACs have 2.44mV LSB I.e. 0.16 fC @ 0pF and0.16 fC @ 0pF 0.32 fC @ 220pF
Werner Riegler CERN, November 2003 Extrapol. Minumum Detectable Charge 2.4 fC, 0.37 fC r.m.s. 2.4 fC, 0.24fC r.m.s Minumum detectable charge is correlated with the sensitivity, I.e. the reason for this Limit is a minimum voltage pulse at the Discriminator input in order to make it fire.
Werner Riegler CERN, November 2003 Offsets Offsets were measured on 272 channels by recording the threshold value that inverts the discriminator output. One DTV sets the threshold for all 8 channels.
Werner Riegler CERN, November 2003 Offsets Channel to channel variations are smaller than chip to chip variations
Werner Riegler CERN, November 2003 Offsets 795.6mV, 9.9mV r.m.s. The threshold DACs on the DIALOG chip have a range of 625mV to 1250mV in 8 bits i.e. bins of 2.44mV. This is perfectly compatible with this kind of offset spread.
Werner Riegler CERN, November 2003 Offsets Subtracting the average offset for each chip and multiplying by sqrt(8/7) gives an rms of 4.54mV. This is the ‘true’ channel to channel variation. It corresponds to 0.3fC at 0pF and 0.6fC at 220pF
Werner Riegler CERN, November 2003 The DTV applies the differential threshold voltage to the discriminator.
Werner Riegler CERN, November 2003 DTV itself has an offset of about 7.5mV r.m.s
Offsets+Sensitivity The channel to channel variation of the sensitivity is <5%. The channel to channel offset variation is around 5mV r.m.s. Together with the DTV the channel to channel offset variation is 10mV r.m.s. Both variations become ‘irrelevant’ when we use individual thresholds.
Werner Riegler CERN, November 2003 Noise Neg: 2240+42e-/pF At 0/100/200pF we can use Pos: 1880+45e-/pF threshold of 1.5/5/10 fC.
Werner Riegler CERN, November 2003 Power Consumption Power consumption is 43.3/46.6 mW/channel for the positive/negative amplifier. On on board (16 channels) the CARIOCA consumes 0.75W. +DIALOG +Voltage drop from regulator ….
Werner Riegler CERN, November 2003 Chamber Test in T11 M3R1 module 1 chamber (double cathode readout) Uniformity of this chamber was measured with CARIOCA9 for the CERN PRR. Crosstalk for single/double cathode readout was evaluated for this chamber with CARIOCA9.
Werner Riegler CERN, November 2003 Chamber test in T11
Werner Riegler CERN, November 2003 Chamber test T11 Dialog -1
Werner Riegler CERN, November 2003 Chamber test T11 Offsets are corrected by 194 individual thresholds. This will finally be done by DIALOG …
Werner Riegler CERN, November 2003 Chamber test T11 All outputs were connected to the LVDS-ECL converter with our ‘final’ shielded twisted pair cables.
Werner Riegler CERN, November 2003 Chamber Test in T11 We used 45mV threshold ( 6-7fC) on all 196 channels. All channels had <50Hz dark count rate. Excellent stability ‘without’ dummy capacitor and without shielding !
Werner Riegler CERN, November 2003 Symmetric Termination Due to the large detector capacitance the frontend is extremely 50 V sensitive to ground noise (C det =100pF, 50 V fires the 5fC threshold). With symmetric termination the chip becomes ‘immune’ to this effect. Penalty: larger noise ! ‘Up to CARIOCA8’ we needed this dummy capacitor since the discriminator firing was causing a large pulse on the chip ground. For CARIOCA9/10, many measures were taken in order to reduce this coupling, especially disconnection of substrate contacts in transistors of the digital part. With the final prototype things work perfectly fine without the dummy capacitor, but we still have this option !
Werner Riegler CERN, November 2003 HV Threshold 7.6,7.4 6.9,7.0 6.7,6.6 5.9,6.2 fC 7.3,6.6 7.3,6.2 6.6,6.8 6.5,6.5 fC Noise 1.3,1.3 1.3,1.2 1.1,1.3 0.6,1.1 fC 1.3,1.3 1.3,1.1 1.1,1.1 1.1,1.2 fC Capacitance 112 108 98 88 45mV threshold on all Pads - Cathode Pad numbers:
Werner Riegler CERN, November 2003 HV Wire Pad Capacitances 26.5-28.5pF Thresholds 6.2, 7.4 fC Noise 0.67, 0.69 fC 45mV threshold on all pads: wire pad numbers
Werner Riegler CERN, November 2003 Cathode Efficiency 95% 2.42kV 99% 2.54kV 95% 2.45kV 99% 2.56kV
Werner Riegler CERN, November 2003 Wire Efficiency 95% 2.4kV 99% 2.5kV 95% 2.43kV 99% 2.55kV
Werner Riegler CERN, November 2003 Detector Capacitance The cathode pad capacitance in the entire muon system will not exceed 120pF, so with the M3R1 chamber we have already tested the largest cathode capacitances ! We will however have wire pad chambers with capacitance up to 220 pF (R4) while the M3R1 chamber has only 30pF wire pad capacitances. Since we don’t have a wire pad chamber we measured the efficiency by adding capacitors to the wire pad.
Werner Riegler CERN, November 2003 On Chamber Wire pad Noise packaged and non packaged chip
Werner Riegler CERN, November 2003 Wire Pad Efficiency for different Capacitances nonpackage side package side
Werner Riegler CERN, November 2003 Efficiency 2.5kV is a good working point that gives >95% efficiency on the double gap (>99% on the quad gap). 2.65kV is a good working point that gives >99% efficiency on the double gap.
Werner Riegler CERN, November 2003 Crosstalk Crosstalk: Probability of firing the Neighboring pad (infinite time window) Plot presented at the PRR: Measured with CARIOCA9 on the M1R3 Prototype on Pad Position P9,7/10. We decided to use doubel cathode readout since we can survive with 10% crosstalk. In M2M3R1R2 the trigger granularity is given by the wire pads, not the cathode Pads. Crosstalk ‘only’ increases the rate.
Werner Riegler CERN, November 2003 Crosstalk CARIOCA9, single, thr 4.7fC, position P9,7/10 CARIOCA9, double, thr 6.8fC, positionP9, 7/10 CARIOCA10, double, thr 7fC, position P11,7/10,no package (S1S2) CARIOCA10, double, thr 7fC, position P11, 7/10, package (S3S4) CARIOCA10, double, thr7fC, position P13, 3/14, no package CARIOCA10, double, thr 6.7fC,position P13,3/14,package (S3S4) ??????????????
Werner Riegler CERN, November 2003 Crosstalk The preamp input stage was actually changed for CARIOCA10 in order to improve the signal tail at large capacitances (phase margin). The design value was 50 since from simulations we know that this is a good value (ASDQ++ used 25 ).
Werner Riegler CERN, November 2003 Crosstalk Fraction Injecting a delta signal in one pad finds a signal on a neighbour pad. We call the ratio of the two pulse heights the crosstalk fraction.
Werner Riegler CERN, November 2003 Crosstalk Fraction The crosstalk fraction of the M3R1 chamber using CARIOCA10 is 1.6-2.2%. It is 10-30% larger than for CARIOCA9. This is a small increase and the 2.2% crosstalk fraction is well within our specifications. Some time ago we found that we have >95% efficiency if our threshold is at 99% efficiency of our threshold is 95% efficiency if our threshold is at 99% efficiency of our threshold is <20% of the average signal (1.5mm pitch). With a crosstalk fraction of 20% and 2.2% crosstalk fraction there is no way to have such a large crosstalk !
Werner Riegler CERN, November 2003 Crosstalk Simulated Pulse Height Spectrum MEDIAN is at 50. Crosstalk is defined as the probability That a neighbor pad fires. This depends on Gas Gain and threshold. Crosstalk Fraction is defined as the fraction of Pulse height on a neighbor pad. This is defined by the pad-pad capacitance and Can be measured in the lab.
Werner Riegler CERN, November 2003 Crosstalk Threshold (fraction of MEDIAN) 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12%. 20%
Werner Riegler CERN, November 2003 Threshold Calibration At the point where the hitefficiency is 50%, the threshold is at the MEDIAN Pulse Height. The voltage where the double gap efficiency is 95% marks the beginning of our plateau. The voltage where the double gap shows 99% efficiency is difficult to find. Therefore we define it as the voltage Where the single gap efficiency exceeds 90%. Knowing the gas gain curve allows To define the threshold in terms of Fraction of the MEDIAN signal. Easy to obtain !
Werner Riegler CERN, November 2003 Gas Gain No space charge effects up to 2.75kV Gas gain doubles for V of 106V
Werner Riegler CERN, November 2003 Crosstalk >95% efficiency if the threshold is at <15% of the median signal. >99% efficiency if the threshold is <7% of the median signal. At 2.65kV threshold is at 5% of the median signal At 2.75kV threshold is at 2% of the median signal !!!! The large crosstalk is real ! The double cathode Readout and the change from 1.5mm to 2mm pitch brought us to the edge of the specifications !
Werner Riegler CERN, November 2003 High Rate Tests Inefficiency due to signal pileup. Since the muon trigger uses a 5 out of 5 coincidence, each of the 5 stations has to be >99% efficient. Therefore the signal width is a crucial number. It is not only determined by the electronics, there is a detector intrinsic Dead time due to arrival of the electrons. Since we use an OR of two frontend channels per station, the rate of correlated hits is the crucial number. For uncorrelated hits, we still have 99% efficiency per station even if one frontend (double gap) has only 90% efficiency. Out goal is a dead time of <50-60ns. In addition to the deadtime (geometrical) we have of course some baseline fluctuations … 1.5mm pitch, Arrival time of the last electron is 25ns.
Werner Riegler CERN, November 2003 High Rate Tests Positive AmplifierNegative Amplifier Am241 is definitely a ‘worst case’ background signal (60keV gamma)
Werner Riegler CERN, November 2003 Charge/Hit at GIF Cs 137, 662keV gammas Dividing the total chamber current by the count rate at 7fC threshold. The MIP charge is calculated by assuming 100e-/cm and a measured gain curve, It is not a very reliable number …..
Werner Riegler CERN, November 2003 TDR Numbers assuming correlations from LHCb 2000-089 Worst case behind the Calorimeter: 870kHz Cathode, 1150kHz Wires Station 1 doesn’t even work on paper
Werner Riegler CERN, November 2003 High Rate Tests at GIF In the experiment we will have high energy muons in presence of ‘photon’ (electron) background. The ideal situation is the muon beam at GIF. We didn’t have time to do this test – next chance only may next year. There is another way of testing the high rate behaviour I.e. signal pileup and baseline fluctuations – S-curve in presence of the background particles.
Werner Riegler CERN, November 2003 High Rate Tests at GIF Chamber was positioned very close to the source. Threshold set to 7fC like in the T11 testbeam. At out working Point of 2.5kV we find exactly the maximum rates expected in the experiment (behind Calo) 1255kHz wires 920kHz cathodes Rate increases with HV because of the Compton spectrum … The steep increase on the Cathodes is due to the crosstalk
Werner Riegler CERN, November 2003 S-Curve at High Rate Inject a signal delta signal on the pad and count the coincidence of the Chamber output signal with a correlated 20ns gate. With source off one gets the ‘standard S-curve. With source on one gets all the information on rate, efficiency and baseline fluctuations. Rate Efficiency Baseline Derivative gives the noise+baseline Fluctuation.
Werner Riegler CERN, November 2003 S-Curves at GIF 0, 2.5, 2.65 kV
Werner Riegler CERN, November 2003 EfficiencyEfficiency >99% efficiency at low rate About 4% ‘geometric’ Efficiency loss at 2.65 kV and 1.5MHz ! Compatible with <50ns deadtime. !
Werner Riegler CERN, November 2003 Noise Noise increases ‘slightly’ with the rate. Has to be evaluated more carefully … Derivative of the S-curve gives the ‘Baseline Probability’ (Noise+Baseline fluctuations) 0, 2.5, 2.65 kV
Werner Riegler CERN, November 2003Conclusions Up to now, CARIOCA10 works according to specifications. Still missing: Analog shapes, test pulse feature, input resistance, radiation tests, input protection, large pulse baseline recovery, …. DIALOG will arrive Feb1st 2004 There is still enough time for CARIOCA tests. In case we will find a problem on CARIOCA10 we will have to consider a submission in Q1 of 2004 which would shift our milestones but would not kill us. Francis Anghinolfi agreed to do the design changes in case it is necessary. The DIALOG still contains the ASDQ features, I.e. we are still free to chose ….. We have to understand M1 and all background rates much better We should by no means exceed 1MHz rate/fronted.