Monitoring system for the HCAL prototype

1
Monitoring system for the HCAL
prototype

• Preparation of the test beam for HCAL
• LED monitoring system
• - monitor stability of tile-fiber system SiPM
• - cover the dynamic range of data taking
• maybe monitor the saturation of SiPM
• Temperature monitoring system

2
Requests for LED monitoring system
Monitoring stability of MIP calibration ?
during run, in between spills, 1Hz measurement
low gain, MIP-like LED light ? need to
take 2 pedestals one for LED (in between
spills) one for data (during
spills) Calibration determination of SiPM gain
? at the beginning of every
run, 100Hz measurement 10k events,
high gain, low LED light (single pe)
10k events, high gain, MIP-like LED
10k events, low gain, MIP-like LED Monitoring
saturation curve parameters ? daily/weekly
10k events x 5 points, high gain,
min-3MIP LED light 10k events x 20
points, low gain, ½ MIP-max LED light
5 min
30 min
3
LED monitor design
18 pairs LEDPhotodiode

• Present status of design
• LED PD board easy to exchange
• Light-tight connection of the board l on
  cassette frame
• Connections
• 1 LED voltage supply 30-60V
• 1 Photodiode voltage supply
• 1 PD-preamp V supply
• 1 Trigger input (NIM, neg.)
• 18 signal outputs from the PDs, pos., 500 ns
  shape
• 1-2 Temp. sensors on board

4
LED choice Blue vs UV
UV LED to monitor scintillator WLS fiber
SiPM - several types tested - best one 30
above the others - small LY spread over many
fibers 15 - all of them very slow 20ns to
max LY ? NEW LED from NIU 30 more LY Blue
LED monitor only WLS fiber SiPM - slightly
less LY than UV (20 ) when
shining on tile LED from
www.roithner-laser.com and www.led-shop24.de Best
choice UV LED LED405-02V (405 nm, 10mV _at_ 20mA,
12o)
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Status of LED monitoring system

• Chosen LED monitoring setup 1 LED 20 clear
  fibers 1 PD ?
• 18 tiles monitored by each LED
• Fiber inserted in a 0.5cm hole on the G10 board,
  fixed with reflector foil
• Max LY achieved with our best LED 0.5mm
  Luminous fiber ? 60 MIP
• Improvements
• ? 0.75mm Luminous fiber factor 2
• ? new LED from NIU factor 30
  (3mm Ø, 30o,UV)
• Still to check (on LED side)
• gt LY spread form new LED (smaller diameter)
• gt LY spread on new mock-up
• gt UV light attenuation on clear fiber
• gt ageing of clear fiber with UV light
• gt comparison of LED signal to MIP signal

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Test setup
30 fibers, ? 0.5 mm UV LED LY spread on bundle
output 15
0-11 V, 20ns pulse 100 Hz ? LED
signal rise time MIP rise time
MIP rise 11 ns
fall 46 ns
LED rise 11 ns fall 45 ns
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Driving monitoring the LED
-LED pulser -LY _at_ 30V with Petr pulser LY _at_
11V on standard pulser -saturation of LED light
_at_ 30 V in Petr pulser ? is 60 V needed? -LED
frequency -during beam data taking ? 1
Hz -during special calibration ? 100Hz -PIN
diode signal (with present preamp) -rise 50ns,
fall 80ns -noise factor 10 larger than SiPM
noise -S/N factor 2-3 larger than PM
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More about the system stability
-long term LED stability checked (1 month of
data analyzed by Evgeni) -often jumps observed in
LED LY -after correction stability of 1 for
SiPM (3 on APD dominated by noise)
APD/PD APD PD
15days
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Temperature stability
Warm up LED directly Warm up
LED in water
Preliminary check
27oC?? oC
26oC?41oC
Consistent response of PM and PIN diode Direct
warm up is too fast and T cannot be controlled ?
LED variation lt 0.5 / oC
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LED Stability in the lab
Almost stable temperature over 15h
Study the spectral changes of LED light
emission 2 deviation of PM and PD measurement
can be related to sensitivity to different light
spectra ? maybe use WLS-fiber to
connect PD ?
PM PD
First look
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LED/SiPM cross talk

• measured SiPM signal with LED off
• compared to LED on but light screened
• 0.25pC cross talk on SiPM with LED at lt 1cm
  distance
• (MIP 10mV 2.5pC)

LED MIP max LED LY
LED off
Peak to peak 2.8 mV
5.8 mV
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SiPM saturation curve

• Response function of SiPM obtained with 3 LED
  fibers perpendicular to the tile
• good reproducibility
• good agreement with saturation curve with

Npixel 1500 , geom. eff. 0.12 , xtalk 0.15
a.u.
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Temperature monitoring

• Platinum resistors
• interpolate 5 readout points
• 2 r/o on LED board
• 2 r/o on mother board
• Total gt 300 readout signals
• Multiplexed r/o

Project in collaboration between Prague-DESY
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Temperature monitoring(scalable system)
no time constrain all ch. can be multiplexed
AD590 Current RO
from Sven Karstensen Milan
15
Slow control schematic
Temperaturemonitoring(Phoenix contact)
Motor control and monitoring(Siemens S7)
Power Supply control and monitoring(W-ie-ne-r)
CAN-bus
CAN-bus
Linux PCwith PVSS
TCPIP
Connection to the worldORACLE, ODBC, TCPIP,
HTTP, WAP
from Sven Karstensen