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Internship Presentation
Detectors Calibration
BONAMY Geoffrey
Under the supervision of Nicolas Delerue
01/07/2016
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Contents
I. Introduction
II.Theory
III. Experiment equipment
IV. Acquisition module characterization
V.Detectors calibration
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INTRODUCTION
● Coherent Smith-Purcell Radiation
● Pyrodetectors
Fig. Nicolas Delerue
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THEORY
Coherent Smith-Purcell Radiation
Coherence :
Bunches Size :
Wavelength :
Picosecond bunch 300μm
Fig. Nicolas Delerue
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EXPERIMENT EQUIPMENT
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Pyrodetectors
Sensitive part
Surface Charge :
Current :
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Acquisition Module
1 Channels input
2 Connections
3 Trigger input
4 Supply input
The DAQ have Two thread :
● Read from the ADC and save in files
● Communication with the user with an interface.
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Acquisition Module
CommunicationEach channel is referenced by is number ( 0 to 7 )
Value for the Amplitude and Offset goes from 0 to 255
Characteristics
Give an answer on 4.096V.
Coded in 8 bits gives 256 values
Uncertainty on each sample in Volts :
4.096/256 = 16mV
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DAQ Characterization
● Why ?➔ Detectors plugged into the DAQ
➔ Need to understand the errors
● How ?➔ Find a reproducible method
➔ Analyse data with Python
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DAQ Characterization
● Reproducible Assembly
➔ Pulse generator.➔ Very precise➔ different signals shapes➔ Tree to split the signal
● Code in python
➔ Licence free
Approach
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DAQ CharacterizationApproach
Observations
● Dependency : Amplitude/ frequency
● Difference between the 8 Channels response
30Hz 50Hz
100Hz70Hz
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DAQ Characterization
Solution
Fit : Offset + A * sin(ω*x + φ )
● Python code using curve_fit* function
● Analyse Amplitude, offset, sampling rate.● Uncertainty on the value
*Return the best parameters using non linear least squares method.
Approach
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DAQ CharacterizationApproach
Uncertainties ● 16mV uncertainty included in the
fit function.● Plot on 1800 samples
Uncertainty order :0,1 mV for 30Hz and 50Hz.1mV for 70Hz and 100Hz.
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AmplitudeLink with the frequency
Oscilloscope signal Acquisition with the DAQ
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Amplitude
● Link with the frequency● Difference regarding :
● Channels● Days
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Offset
● No significant link with the frequency during one day.
● Difference regarding :● Channels● Days within the uncertainty
Easily manageable.
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Sampling rate
No Difference regarding :
● Channels● Days
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DAQ Characterization
Amplitude Offset Sampling rate
Variation with channels
Yes Yes No
Variation regarding the day
Yes Yes No
Variation with frequency
Yes Not significant X
Conclusion
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Detectors CalibrationAssembly
Translation stage
Pyrodetectors
Parabolic Mirrorf=10cm Lens
Light bulb
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Detectors Calibration
Conversion between Motor steps and mm100 000 steps = 7.79mm ± 0.61
Photo-diode Intensity and translation characterization
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Detectors CalibrationMisalignment Transversal
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Detectors CalibrationMisalignment Longitudinal
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DAQ characterizationAssembly characterisation
Detectors calibration with light
Studies with IR and FIR
Conclusion
