May 14, 2015Pavel Řezníček, IPNP Charles University, Prague1 Tests of ATLAS strip detector modules: beam, source, G4 simulations Pavel Řezníček Content: ATLAS SCT modules Analog x binary readout Source tests x beam tests Testbeam simulation Source tests simulation

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague2 ATLAS LHC

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague3 ATLAS SCT - one of 3 inner detector subsystems: Pixel, SCT, TRT - length 5.6 m, diameter 1.2 m - rapidity coverage:  placed in solenoidal magnetic field 2 T - optical readout - involved in 2 nd level trigger – holds data in pipelines for 3  s - provides 4 precise point measurement (16 x 580  m) - 4 barrel layers (2112 modules) and 2 x 9 forward wheels (1976 modules) - radiation environment – tests of modules PS by 3·10 14 p (24 GeV) /cm 2 - SCT modules requirements: efficiency > 99%, noise occupancy < x 768 strips, 6/12 cm long - strip pitch 80  m (barrel), 54 ÷ 95  m (forward) - 2/4 64mm x 64mm x 285  m p-on-n detectors (barrel) - opposite planes stereo angle 40 mrad - AC coupled readout - 2 x 6 readout chips (128 channels) - ~ 20 ns shaping time - calibration circuit (mV  fC) - data compression - binary readout

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague4 Analog readoutBinary readout (digitized amplitude)(scanned threshold) - monoenergetic signal (for example calibration pulse) + Gaussian noise (zero mean signal): threshold scan results in s-curve with  ~ noise and threshold of 50% efficiency = monoenergetic signal - particles passing through the detector: energy loss fluctuations + particle energy spectrum sources of signal: calibration pulse, MIP,  -, laser working conditions: threshold ~ 1 fC Landau distribution 90 Sr ( 90 Y)  - spectrum Testbeam threshold scan  - test threshold scan Calibration process, noise measurement (QA tests of all modules) Test of few modules only

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague5  - source testsTestbeam - relativistic electrons (kinetic energy < 2.2 MeV)- MIP (180 GeV pions) - simple construction- expensive - various geometrical settings- also possible + strong magnetic field (1.56 T) - repeated tests (before and after irradiation)- only few (up to ~ 15) modules can be tested - available at any time- available ~ 3 x 14 days a year - quick measurement and analysis- slower measurement, complicated analysis (alignment) - no particle track measurement (except DUT)- analogue telescopes (microstrip detectors) - angular spread of particle tracks, multiple scattering- parallel tracks energy loss (Geant4)

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague6 - efficiency (not reliable at low thresholds) - efficiency (reliable at all thresholds) - median (threshold of 50% efficiency)- median - noise occupancy (reliable measurement- noise occupancy and efficiency within from QA tests – ENC in advance)specifications (99% efficiency, 5·10 -4 noise occupancy) - average width of strips clusters ……charge sharing,- angular and magnetic field dependence at 1 fC  -electrons,threshold for (un)irradiated modules crosstalk  - source testsTestbeam - multiple scattering => stronger charge sharing => different results on both detector planes

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague7 - bias voltage dependence of medians for (un)irradiated modules  - source testsTestbeam - checking bonding - dead or noisy channels can be found- dead and noisy channels are found as well, wrong using standard QA tests, laser tests can be used as wellbonding by using residuals (alignment, telescopes) - detector behavior at its edges - wrong bonding - large clusters needed (incidence angle)- interstrip position dependences

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague8 - bias voltage dependence of medians for (un)irradiated modules  - source testsTestbeam - checking bonding - dead or noisy channels can be found- dead and noisy channels are found as well, wrong using standard QA tests, laser tests can be used as wellbonding by using residuals (alignment, telescopes) - detector behavior at its edges - wrong bonding - large clusters needed (incidence angle)- interstrip position dependences

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague9 Simulation - histogram: deposited energy spectrum of 180 GeV pions from Geant4 simulation - solid curve: integral of the spectrum - dashed curve: efficiency threshold scan – result of digitization under Athena Geant4 simulation - to explain differences between source and beam tests - to compare simulation to newer beam tests results (2001) Geant4 simulation – energy track segments,  -electrons, multiple scattering, … Athena digitization – S. Gadomski, detectors and electronics response, magnetic field Digitization

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague10 Beam tests simulation – angular and bias dependence - median underestimated (can be fixed) and average cluster 1fC overestimated (?), trends of angular and bias dependencies match - bias dependence – depleted region, diffusion, drift time - angular and magnetic field (0T blue line, 1.56T red line) dependence – charge sharing, track length simulation measurementsimulation measurement

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague11 Beam tests simulation – interstrip position dependence 16 degrees incidence angle perpendicular incidence - pure simulation - simulation corrected to particle track determination uncertainities (multiple scattering, telescopes resolution) and averaging over 6  m wide interval as in testbeam analysis - beam tests -  -dependencies: detailed study of the detectors - can be measured using laser (in development) - efficiency and average cluster size analyzed - low beam tests simulation measurement

May 14, 2015Pavel Řezníček, IPNP Charles University, Prague12 simulation (efficiency, cluster sizes) beam tests (blue) and source test (red) Beam and source tests simulation - ratio of medians from beam tests to the source tests: simulation:1.12 ± 0.02 measured:1.11 ± source tests sensitivity to geometrical settings – low on the detector plane nearer to the radioactive source (both simulation and measurements)