High Rate Photon Irradiation Test with an 8-Plane TRT Sector Prototype Juan Valls CERN For the ATLAS-TRT Collaboration LECC 2002

Goals Characterize and study the performance of near to final TRT FE electronics Demonstrate basic operation of the detector at high counting rates Two high rate irradiation tests planned CERN X5 GIF 137Cs (662 keV photons), 0.5 MHz Weizmann Istitute Irradiation Facility 60Co (1.1 and 1.3 MeV photons), 0.5-20 MHz J. Valls - LECC 2002

Transition Radiation Tracker Radiator Straws Radiator Straws J. Valls - LECC 2002

Outline Goals FE Electronics Experimental Setup Results Summary CERN X5-GIF Weizmann Institute Irradiation Facility Results Occupancies and Rates Occupancy Cross-Talk Hit Detection Efficiencies Summary J. Valls - LECC 2002

TRT Endcap Sector Prototype FE Boards 8 planes x 24 straws = 192 straws Web boards J. Valls - LECC 2002

Web Boards Arc-shaped PC boards HV traces and petals Signal circuit J. Valls - LECC 2002

Endcap FE Electronics ASDBLR Boards (8x3 = 24 ICs) 192 channels DTMROC Flex Boards (4x3 = 12 ICs) J. Valls - LECC 2002

ASDBLR and DTMROC ASDBLR Amplifier Shaper Discriminator with Baseline Restoration DTMROC Digital Time Measurement and ReadOut Controller See yesterday talk from V. Ryjov on DTMROC-S Session A22 J. Valls - LECC 2002

FE Characterization Calibration of individual DTMROC threshold DACs relationship between DAC counts and voltages Calibration of individual ASDBLR channels relationship between input signal amplitude and discriminator thresholds Gains, Noise, Offset Threshold Spreads J. Valls - LECC 2002

DTMROC Calibrations ~5.3 mV/DAC V/DAC V/DAC (low1) (low0) V = f(DAC) (high0) V/DAC (high1) ~5.3 mV/DAC J. Valls - LECC 2002

ASDBLR Calibrations Measure S-curves for different input signals to extract gain and discriminator offsets Threshold scans for a given input signal are characterized by S-curves J. Valls - LECC 2002

ASDBLR Calibrations Low Threshold High Threshold Gain Gain Offset 0.86 ± 0.09 mV/eV (gain) 122 ± 30 mV (offset) 0.07 ± 0.01 mV/eV (gain) 99 ± 27 mV (offset) Noise ~ 30.8 mV  38.5 eV J. Valls - LECC 2002

ASDBLR Calibrations Occ = f (DAC) Before calibration Occ = f (eV) After Vinp = 0.5 mV (~ 230 eV) J. Valls - LECC 2002

ASDBLR Threshold Spread Offset Threshold Spread w.r.t. Nominal Threshold (chip average) Nominal Threshold = 200 eV 12 ASDs shown All 192 channels  50 eV  50 eV J. Valls - LECC 2002

X5- GIF Facility Irradiator X5 GIF Facility Radioactive 137Cs photon source (662 keV) X5 GIF Facility Test area with an adjustable high background flux of photons, simulating high rate background conditions Maximum Photon Flux ~ 107 /s/cm2 Hit Probability per Photon (0.2 mm Al converter) ~ 0.5 - 1 % Charged Particle Rate 5x104 electrons/s/cm2 (LHC ~ 106 particles/s/cm2) J. Valls - LECC 2002

Weizmann Irradiation Area 0.5 MHz 1.0 MHz Gamma Source 15.0 MHz 19.0 60Co 9.4 MHz 2.7 Gamma Source Shielded (5 cm Lead) 4.7 60Co 1.1, 1.3 MeV J. Valls - LECC 2002

Flex board WEB 1 WEB 2 Special web flap configuration with analog control Photon Source Straws sharing different web flaps (3 flaps per web) DTMROC (2 ASDBLRs) 16 straws ASDBLR (HV Group) Flex PCB J. Valls - LECC 2002

Occupancy Definitions Straw Occupancy Ratio of events with at least one hit over total number of events Rates calculated from occupancies Hits LT hits: at least one low threshold bit set LE hits: at least one leading edge HT hits: at least one high threshold bit set (Occupancies obtained from data for either 1 or 3 beam crosses) J. Valls - LECC 2002

Noise Occupancies and Rates Weizmann 1.3  1.7 % (3 BC) Noise Occupancy LE LT Occupancies (%) Rates (MHz) Noise Rate 169  221 kHz (3 BC) X5 GIF 1.0  1.1 % (3 BC) 130  143 kHz (3 BC) (200 eV) 250 eV 250 eV J. Valls - LECC 2002

Analog Monitoring Straw Rates Analog Monitoring Straw (MHz) Leading Edge (250 eV) High Threshold (3 keV) 0.5 1.4 ± 0.8 1.0 ± 0.2 1.0 2.4 ± 1.2 1.6 ± 0.2 2.7 3.6 ± 1.2 3.0 ± 0.5 4.7 5.2 ± 1.4 4.4 ± 1.0 9.4 9.6 ± 2.8 10.3 ± 1.8 15.0 10.5 ± 2.8 13.7 ± 1.9 19.0 12.0 ± 3.4 19.5 ± 3.1 J. Valls - LECC 2002

Irradiation Area High Rates (softer energy spectrum) Low Rates Gamma Source 15.0 MHz 19.0 60Co 60Co 9.4 MHz 4.7 MHz 2.7 MHz Gamma Source Shielded (5 cm Lead) High Rates (softer energy spectrum) 1.0 MHz Low Rates (harder energy spectrum) 0.5 MHz J. Valls - LECC 2002

Energy Spectrum Shapes Low Threshold Occupancies High Threshold Occupancies LE LT HT Harder energy spectrum at low rates Softer at high rates 1.0 MHz Low threshold occupancies higher at low thresholds for low rates Flat at high rates 15.0 MHz J. Valls - LECC 2002

Test-Beam Energy Spectrums 20 GeV electrons 20 GeV pions J. Valls - LECC 2002

Energy Spectrum Shapes 0.5 MHz 1.0 MHz Low Threshold 300 eV 2.7 MHz 4.7 MHz J. Valls - LECC 2002

Cross-Talk Ccoupl Conductive coupling in the straws which share the same decoupling capacitor Parasitic capacitive coupling at the end of the straws Cblock Riso Signal return HV + filter Internal channel-to-channel cross-talk of the analog ASDBLR chip Cross-talk through connecting traces on the flex-rigid boards and web board J. Valls - LECC 2002

Occupancy Cross-Talk High Threshold Hit Required on a Trigger Straw Straws sharing the same HV group Straws sharing the same web flap High Threshold Hit Required on a Trigger Straw J. Valls - LECC 2002

Occupancy Cross-Talk 5 keV 7 keV 11 keV Background Rate 0.5 MHz 2.7–2.1 increase 3.1–2.9 increase 11 keV 4.0–2.9 increase Background Rate 0.5 MHz ASDBLR HVgroup Web flap Away straws J. Valls - LECC 2002

Occupancy Cross-Talk 3 keV 5 keV Background Rate 2.7 MHz 9 keV 11 keV 1.3–1.2 increase Background Rate 2.7 MHz 1.4 increase 9 keV 11 keV 1.6–1.1 increase 1.6–1.1 increase J. Valls - LECC 2002

Occupancy Cross-Talk 250 eV 400 eV 250 eV 400 eV 0.5 MHz J. Valls - LECC 2002

HT Occupancy Cross-Talk 1.0 MHz 0.5 MHz 2.7 MHz ASDBLR HVgroup Web flap No Cross-Talk in High Threshold Occupancies J. Valls - LECC 2002

Hit Detection Efficiencies Use calibrated internal test pulse signals 15 DAC  600 eV (50% Occ) 21 DAC  1 keV (50% Occ) Test pulse signals adjusted in time to arrive always at the same position (middle BC) Hit efficiency (per channel): fraction of events with a LE hit in a selected time window over total number of events No Irradiation 3 bins J. Valls - LECC 2002

Time Over Threshold Low Threshold 250 eV No Irradiation 1.0 MHz J. Valls - LECC 2002

Time Over Threshold Low Threshold 600 eV 1.0 MHz 0.5 MHz 2.7 MHz J. Valls - LECC 2002

Time Distribution of LEs 15.0 MHz 1.0 MHz 4.7 MHz 19.0 MHz 2.7 MHz 9.4 MHz Low Threshold = 250 eV Loss of width from undershoot and pile-up J. Valls - LECC 2002

Hit Detection Efficiencies Low Threshold 250 eV 300 eV 400 eV 600 eV Test Pulse 600 eV Test Pulse 1000 eV J. Valls - LECC 2002

Hit Detection Efficiencies Lab Measurements 18.6 ns, 2.8 keV 37.2 ns, 3.9 keV 55.8 ns, 3.9 keV Input Test Pulse 600 eV Test Beam These Measurements J. Valls - LECC 2002

Hit Detection Efficiencies Test-Beam Drift-Time “2.5 ” Efficiency Input Test Pulse 1000 eV J. Valls - LECC 2002

Summary (part 1/3) Noise ocupancies (250 eV, middle BC) 0.5%  170 kHz Occupancies under irradiation (250 eV, middle BC) 3.6%  1.4 MHz (data)  0.5 MHz (monitor straw) 13.0%  5.2 MHz (data)  4.7 MHz (monitor straw) 26.3%  10.5 MHz (data)  15.0 MHz (monitor straw) Background energy shapes similar to those from past electron test-beams for most of the data. Harder energy spectrums for data taken at low rates (0.5-1.0 MHz) J. Valls - LECC 2002

Summary (2/3) Occupancy cross-talk Hit detection efficiencies Confirm results from previous X5 GIF test Low threshold occupancies (250 eV) 0.5 MHz  170% - 200% for 5 - 11 keV signals 1.0 MHz  100% - 160% for 5 - 11 keV signals 2.7 MHz  30% - 60% for 5 - 11 keV signals High threshold occupancies slightly affected (<10%) Hit detection efficiencies Up to 5 MHz  > 90% Rapid decrease for > 5 MHz J. Valls - LECC 2002