Physik-Institut
Experimental Methods in Particle Physics (HS 2015)
Electronics, Data Acquisition and
Trigger
- Introduction -
Lea Caminada
Lecture Program
• This week: Electronics and Data Acquisition
– Signal formation
– Analog data processing
– Electronic Noise
– Digitization
• Next week: Trigger and System Level Aspects
– Hardware and software trigger methods for data
selection and rate reduction
– Examples of readout system components and setups
– Thursday (December 10, 13:30): Excursion
à Visit of CMS Pixel Lab at UZH
Reading
• W.R. Leo, “Techniques for Nuclear and Particle Physics
Experiments”, Springer Verlag
• H. Spieler, “Semiconductor Detector Systems”, Oxford
Science Publications
• L. Rossi, P. Fischer, T. Rohe, N. Wermes, “Pixel Detectors”,
Springer Verlag
• U. Straumann, Vorlesungsskript,
http://www.physik.uzh.ch/~strauman/DaqTrigger.pdf
• ETH
– HS: Elektronik für Physiker I (Analog), R. Horisberger
– FS: Electronics for Physicists II (Digital), T. Delbrück
• UZH
– FS: PHY250 Elektronik, A. Vollhardt
– FS: PHY251 Elektronik Kurs, P. Robmann
Lectures
Data Acquisition (DAQ)
Wikipedia: “Data acquisition is the process of sampling signals that measure real world physical conditions and converting the resulting samples into digital numeric
values that can be manipulated by a computer.” Therefore need to:
1) Detect sensor signal (current, voltage) 2) Amplify signal and suppress noise
DAQ at CMS as an example
DAQ at CMS as an example
CMS Detector Cavern Counting Room 15m 7DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors CMS Detector Cavern Counting Room p p 15m
DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors 2) Analog processing of detector signal in electronics on detector • Signal amplification, noise suppression, threshold application, … CMS Detector Cavern Counting Room p p 15m 9
DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors 2) Analog processing of detector signal in electronics on detector • Signal amplification, noise suppression, threshold application, … 3) Data transmission to electronics in counting room CMS Detector Cavern Counting Room p p 15m
DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors 2) Analog processing of detector signal in electronics on detector • Signal amplification, noise suppression, threshold application, … 3) Data transmission to electronics in counting room 4) Digitization CMS Detector Cavern Counting Room p p 15m 11
DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors 2) Analog processing of detector signal in electronics on detector • Signal amplification, noise suppression, threshold application, … 3) Data transmission to electronics in counting room 4) Digitization
5) Digital data transfer to
CMS Detector Cavern Counting Room p p To s u rfa ce 15m
DAQ at CMS as an example
1) Particles produced in
collisions leave signals in sensors 2) Analog processing of detector signal in electronics on detector • Signal amplification, noise suppression, threshold application, … 3) Data transmission to electronics in counting room 4) Digitization
5) Digital data transfer to
servers on surface
• Data storage, event
reconstruction and data analysis CMS Detector Cavern Counting Room p p To s u rfa ce 15m 13
Signal formation in the sensor
Si
300um ~100V
• Charged particles passing through silicon sensor
Signal formation in the sensor
Si
300um ~100V
• Charged particles passing through silicon sensor
generates e/h pairs through ionization
Charge deposited in sensor:
Q = E/E
ie
E: particle energy
Ei: ionization energy
e = 1.602 10-19 C
Example: MIP in 300um Si
E = 100 keV (Bethe Bloch)
Ei (Si) = 3.6 eV
à Q = 4fC. Tiny current!
.
Signal formation in the sensor
Si
300um ~100V
• Charged particles passing through silicon sensor
generates e/h pairs through ionization
Charge deposited in sensor:
Q = E/E
ie
E: particle energy
Ei: ionization energy
e = 1.602 10-19 C
Example: MIP in 300um Si
E = 100 keV (Bethe Bloch)
Ei (Si) = 3.6 eV
à Q = 4fC. Tiny current!
Signal pulse duration
Si
300um ~100V
• Mobility of charge carriers defines pulse duration
v = µ
E(x)
v: velocity µ: mobility
E(x): electric field
Example: 100V across 300um Si
µ(e, Si) = 1350 cm2V-1s-1
µ(h, Si) = 450 cm2V-1s-1
à Collect electrons for
high rate applications
à ve ~ 4.5 106 cm/s
à t ~ 7 ns
Readout of sensor signal and analog
data processing
• Tailor the response of the system to optimize
(according to the experimental goal):
– The minimum detectable signal – The energy measurement
– The event rate
– The time of arrival
– The insensitivity to the sensor pulse shape
Silicon pixel readout electronics
1 cm
50
0 u
m
• Example of hybrid pixel detector: Pixelated sensor is
connected to pixelated readout electronics
Silicon pixel readout electronics
1 cm 50 0 u m 30 0 u m 20 u m 18 0 u m• Example of hybrid pixel detector: Pixelated sensor is
connected to pixelated readout electronics
Sensor pixel cell
Analog electronics in single pixel cell
Preamplifier Pulse Shaper Discriminator
ΔQ Cf Vthr G(ω) Bump-‐bond to sensor
CMS pixel readout chip
Send to periphery: - Further processing - Digitization - Readout - Data storage 21
Coupling of sensors
AC coupled strip detector:"
