Commissioning and Operation of the CMS Tracker analogue optical link system at TIF with CMSSW: R.Bainbridge, A.Dos Santos Assis Jesus, K.A.Gill, V. Radicci

Commissioning of the Optical Link: 5189 laser diodes were tested in the slice test at TIF each laser was tuned, to determine the optimal gain and bias setting, during the standard commissioning procedure with the CMS Tracker online software XDAQ and the analysis software RootAnalyser. A commissioning run is performed for each temperature: 15,10,0,-10,-15 0 C. This analysis is performed using the offline commissioning CMSSW framework (by Rob) Almost completed: 1)Validate CMSSW procedure for the basic configuration of the Optical Link Debug/test the code  Check using TIF data 2)Compare CMSSW – Root Analyser 3)Compare the performances of different Subsystems (TIB TOB TEC) 4)Study performance and detailed temperature effects (nominal 15 0 C, 10 0 C, 0 0 C, C, C) Ongoing: 1.Propose new histograms and variables for link performance (E.g. link noise contribution at different bias values... ) 2.Propose a standard procedure for monitoring of link performance during the Tracker operations (Reliability and radiation effects)

Package: /CMSSW_1_4_0/src/DQM/SiStripCommissioning: /SiStripCommissioningClients/src/OptoScanHistograms.cc (RB) (  /SiStripCommissioningAnalysis/src/OptoScanAnalysis.cc) Source_run#.root For each Gain produces: 1) Summary Histos_run#.root (not yet implemented!) 2) debug_7531.log file RU file stored on Castor + Cabling from Online DB /SiStripCommissioningSources/src/OptoScanTask.cc (RB) GainSummaryPlot.cc (VR) Summary plots.gif.root *Actual Gain : 0 *LLD bias setting : 21 *Measured gain [V/V] : *'Zero light' level [adc] : *Link noise [adc] : *Baseline 'lift off' [mA] : *Laser threshold [mA] : *Tick mark height [adc] : *Actual Gain : 1 *LLD bias setting : 20 *Measured gain [V/V] : *'Zero light' level [adc] : *Link noise [adc] : *Baseline 'lift off' [mA] : *Laser threshold [mA] : *Tick mark height [adc] : *Optimum LLD gain setting : 1 Analysis Procedure:

W W/2 Lift Off Laser Threshold = Lift Off –W/2 Tick Mark hight = W * Base Slope Measured Gain = Tick Mark * (1/0.8) * (1.024/1024) Best Gain ~= 0.8 Bias setting = Lift off + 2 Zero Light Level Laser Bias (I2C) 1 count = 0.45 mA FED output Laser Current = (Laser Thr * 0.45) mA Overlapping range 50% range “Tick” “Base” Fit to points within the 20% and the 80% of the range Coded by Rob

RUN #T nom ( 0 C)Partition TIBTOBTEC (reduced # of Connection) TIBTOBTEC TIBTOBTEC TIBTOBTEC TIBTOBTEC TIBTOBTEC TOB PP TEC TEC TIB PP TIB TOB Variables Monitored: 1)Best Gain 2)Bias Setting 3)Measured Gain 4)Base Slope 5)Tick Mark hight 6)Zero Light Level 7)Lift Off 8)Laser Thresold

Few Plots

@ different gains Bias Setting for different subsystem Measured Gain Target Gain = 0.8 Mainly Gain = C - Run 11309

Tick Height Slope vs Tick Base slope W = (Slope / Tick) -1 Independent on the subsystems and Gains (Laser + LLD) (Laser + LLD + APV) Input tick to link (=APV output tick) Different behavior TIB, TOB, TEC due to the different low voltage drop (see A. Venturi talk) C - Run 11309

Baseline lift off (mA) Laser threshold (mA) Zero Light Level  Trim DAQ value C - Run This distribution strongly depends on the temperature of each Fed channel. Gain 0 Correlated to Laser th = Lift off – W/2 - Related to the AOH temperature Double peak in TIB modules Structured peak in TOB and TEC TOB always higher  To compare with the distribution from the production

Digression: “Why double peak in laser th distribution?”

TIB Double SidedTIB Single Sided Fiber 1 Fiber 2 Fiber 3 Ccu26 ccu28 ccu30 Ccu27 ccu29 ccu31

CERN, 9 th October 2007 V. Radicci 12 Laser temperature “Tracker Map”: (fiber gain T=150C) “CMS Tracker Map Visualization” tool used here to map the laser temperatures: - TOB is hotter - two different temperatures for TIB modules (green and yellow in the map)  double peak in the TIB distribution Laser Threshold distribution Color scale from Red = hot to Blue = cool TIB Layers TOB Layers TID Disks TEC Disks - Powerful tool also for mapping the tick height, base slope… - Interesting results will come from the correlation between Tick and Laser Temperature CERN, 9 th October 2007 V. Radicci 12

CMSSW vs RootAnalyser:

CMSSW RA (T=-10 0 C) Difference channel by channel between Best Gain(CMSSW) – Best Gain (RA) 3.4% with diff>0 1) Comparison of Best Gain chosen for each laser

CMSSW RA Difference channel by channel between Bias (CMSSW) – Bias (RA) 16% with diff>0 mainly ±1 1) Comparison of Bias setting chosen for each laser

Due to the different gain Good agreement Robust performance of new code

Measured Selected Gain  comparison with the simulation

T=15 0 C T=10 0 C T=0 0 C T=-15 0 C T=-10 0 C Range 0.62 V/V – 0.96 V/V independent from temperature in Agreement with simulation! G0G1G2G3 T=15 0 C3.8%84.4%10.4%1.2% T=10 0 C7.3%84%7.8%0.7% T=0 0 C18.9%76.4%4.1%0.5% T=-10 0 C34%63.4%2%0.3% T=-15 0 C40.1%58.3%1.3%0.3% Gain spread looks reasonable. Usual effect of increased gain with higher temperature. Values to be compared with simulation

Temperature dependence – all distributions are fitted with a Gauss function, the mean and the error are plotted as a function of Temperature

Nominal cooling temperatures !! The parameterhave to be determined by comparing with other measurements: PLC, DCU - Laser threshold current is temperature dependent. - Different values with gain and subsystems at the same nominal temperature! - The the laser threshold (I th ) can be used to evaluate the actual laser temperature T according its known exponential behavior:

T Warm – T +10 T Warm – T 0 T Warm – T -10 T Warm – T -15 In order to compare the AOH temperature and 1)the temperature of the cooler or of the air (PLC measurements), 2)the temperature of the sensor and of the hybrid (DCU readings) we can considering the temperature variation ΔT=(T 1 -T 2 ), measure on the same element (laser, hybrid…), for different experimental condition. ΔT evaluated from I th for different values of

Mpv from the fit Warm : C Warm : 0 0 C Warm : C Warm : C C : C DCU- Hybrid DCU- Sensor PLC Warm : C ~4.9 Warm : 0 0 C ~15.1 Warm : C ~23.5 Warm : C ~ C : C To be checked!!!! A. Venturi

Now “the laser is a good thermometer” !!! Note large ΔT over nominal

Effect of T on link gain and tick mark height (Laser + LLD) Tick height at FED (Laser + LLD + APV) Input tick to link (=APV output tick) Laser alone W = Tick Height / Base Slope Measured gain prop to Tick

Fit slope: G0: G1: G2: G3: Decrease = (0.55±0.02) % / 1 0 C Fit slope: G0: -2.4 G1: -3.1 G2: -4.4 G3: -5.8 Decrease = (0.49±0.03) % / 1 0 C Gain change seems dominated by laser –Individual lasers vary more and do not necessarily follow average trace APV tick is constant!

Fit slope: G0: G1: G2: G3: Decrease = (1.0±0.1) % / 1 0 C Fit slope: G0: 0.18 G1: 0.19 G2: 0.18 G3: 0.18 Decrease = (1.0±0.1) % / 1 0 C Particular behavior of the Zero light level an explanation could be considering the fed temperature channel by channel

Conclusion –Links commissioning software/analysis in use on TIF data CMSSW code stable –New parameters included »Laser threshold, noise, tick input height –Able to check out detailed effects –Move development effort now onto details of performance (e.g. noise) and monitoring (Ana talk)