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

2. 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), MHz
J. Valls - LECC 2002

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

4. 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

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

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

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

8. 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

9. 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

10. 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

11. 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

12. 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  eV
J. Valls - LECC 2002

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

14. 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

15. 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)
~ %
Charged Particle Rate
5x104 electrons/s/cm2
(LHC ~ 106 particles/s/cm2)
J. Valls - LECC 2002

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

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

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

25. 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

26. 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

27. 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

28. 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

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

30. 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

31. 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

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

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

34. 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

35. 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

36. 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

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

38. Summary (part 1/3)
Noise ocupancies (250 eV, middle BC)
0.5%  170 kHz
Occupancies under irradiation (250 eV, middle BC)
3.6%  MHz (data)  MHz (monitor straw)
13.0%  MHz (data)  MHz (monitor straw)
26.3%  MHz (data)  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 ( MHz)
J. Valls - LECC 2002

39. 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 keV signals
1.0 MHz  100% - 160% for keV signals
2.7 MHz  30% % for 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