vlvnt09, athens, greece, 13-15 october 2009 time over threshold electronics for neutrino telescopes...
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VLVnT09, Athens, Greece, 13-15 October 2009
Time over Threshold Electronics Time over Threshold Electronics for Neutrino Telescopesfor Neutrino Telescopes
Time over Threshold Electronics Time over Threshold Electronics for Neutrino Telescopesfor Neutrino Telescopes
George Bourlis
In the framework of the KM3NeT Design Study
VLVnT09, Athens, Greece, 13-15 October 2009
Time over ThresholdTime over ThresholdTime over ThresholdTime over Threshold
Analogue signal
Comparators’ output
t1t2t3 t4 t5 t6 HPTDC output
VLVnT09, Athens, Greece, 13-15 October 2009
Readout ElectronicsReadout ElectronicsReadout ElectronicsReadout Electronics
GPS Input
USB PortTrigger Output5 PMT Signal Inputs
25ps accuracy TDC
HPTDC
• 32 channels (LR) – 8 Channels (HR)
•25ps (HR) to 100 ps (LR) accuracy
•Self Calibrating
VLVnT09, Athens, Greece, 13-15 October 2009
Readout ElectronicsReadout ElectronicsReadout ElectronicsReadout Electronics
VLVnT09, Athens, Greece, 13-15 October 2009
EZ-USB FX2 HPTDC CONTROLEZ-USB FX2 HPTDC CONTROLEZ-USB FX2 HPTDC CONTROLEZ-USB FX2 HPTDC CONTROL
VLVnT09, Athens, Greece, 13-15 October 2009
Board Debugging ConfigurationBoard Debugging ConfigurationBoard Debugging ConfigurationBoard Debugging Configuration
Trigger
Input
splitter
splitter
discriminator
- Offset of each input
- Scale of each input
- Timing among input channels
- Minimum threshold that can be applied to the channels of each input
VLVnT09, Athens, Greece, 13-15 October 2009
Multiplication factor vs ThresholdsMultiplication factor vs ThresholdsMultiplication factor vs ThresholdsMultiplication factor vs Thresholds
- Pulses exceeding 2V are not distorted but truncated and can still be reconstructed
Multiplication factor 1x 1x 1.5x 2.5x 5x
Measured factor 0.991 1.0035 1.503 2.7735 4.995
Minimum Threshold (mV) 9.78 5.25 1.69 1.57 1.42
Maximum Threshold (mV) 2000 2000 1333 800 400
- 1.57mV corresponds to around 1/3 of a MIP for the HELYCON detectors
- 800mV corresponds to 150-200 MIPs for the HELYCON detectors
VLVnT09, Athens, Greece, 13-15 October 2009
Charge (pCb)
Single pe
HELYCON PMT & DetectorHELYCON PMT & DetectorHELYCON PMT & DetectorHELYCON PMT & Detector
Photomultiplier Tube
PH: XP1912
At “nominal” High Voltage
Gain: ~ 4 105
<charge>/p.e. ~ 0.07pCb
<pulse height>/p.e. ~ 1.05mV
Rise Time: 1.2 ns
Charge (in units of mean p.e. charge)
At the Detector Center
Data
- Monte Carlo Prediction
VLVnT09, Athens, Greece, 13-15 October 2009
Sample PulsesSample PulsesSample PulsesSample PulsesInput 1
VLVnT09, Athens, Greece, 13-15 October 2009
Charge vs Time over ThresholdCharge vs Time over ThresholdCharge vs Time over ThresholdCharge vs Time over ThresholdC
ha
rge
(p
C)
Time Over Threshold (s)
1st Threshold only 1st & 2nd Threshold 1st, 2nd & 3rd Threshold
4mV
50mV
15mV
3 thresholds
VLVnT09, Athens, Greece, 13-15 October 2009
Charge versus Time over ThresholdCharge versus Time over ThresholdCharge versus Time over ThresholdCharge versus Time over Threshold
3mV
70mV
10mV20mV
40mV
100mV
6 thresholds
The chosen thresholds allow the reconstruction of higher pulses with good accuracy, while smaller pulses (fewer thresholds crossed) can still be reconstructed with acceptable accuracy
VLVnT09, Athens, Greece, 13-15 October 2009
Charge ParameterizationCharge ParameterizationCharge ParameterizationCharge Parameterization
kkCharge= a (tot)
Parameterization of the charge vs the sum of the times over threshold for each of the areas were 1, 2, 3, 4, 5 or 6 thresholds were crossed
VLVnT09, Athens, Greece, 13-15 October 2009
Charge EstimationCharge EstimationCharge EstimationCharge Estimation
- Estimated Resolution 4.3%
- Pull distribution sigma of 1.04 ± 0.07
Measured Charge – Estimated Charge
Measured Charge
4 thresholds
Measured Charge – Estimated Charge
Estimated Error
VLVnT09, Athens, Greece, 13-15 October 2009
Charge Estimation ResolutionCharge Estimation ResolutionCharge Estimation ResolutionCharge Estimation ResolutionCharge estimation resolution vs number of thresholds crossed
Thresholds crossed 1 2 3 4 5 6
Charge estimation resolution (%) 13.6 6.9 5.6 4.3 3.4 2.9
VLVnT09, Athens, Greece, 13-15 October 2009
ConclusionsConclusionsConclusionsConclusions
- The time over threshold technique allows for charge estimation with very good resolution for higher pulses (even if the thresholds do not go very far up the pulse height). This resolution goes down to ~3% with 6 thresholds which is sufficient both for the HELYCON and the KM3NeT telescopes.
- Lower pulses can still be reconstructed with acceptable accuracy if the lower thresholds are more closely spaced near the baseline.
- Charge estimation resolution depends on the number of thresholds crossed and on their specific values. The choice of the applied thresholds depends on the pulses recorded.
VLVnT09, Athens, Greece, 13-15 October 2009
Sample PulsesSample PulsesSample PulsesSample PulsesInput 1