Transcript Poster_TWEPP08a4

Electronics of LHCb calorimeter monitoring
system
A.Konoplyannikov for the LHCb Calorimeter Group
Poster for Topical Workshop on Electronics for Particle Physics September 15-19, 2008, Naxos, Greece
LHCb calorimeter Detectors
Calorimeter System Photo-Detectors and LED monitoring Optics
for precise measurements of CP violation and rare decays:
for precise monitoring phototube stability
All calorimeters are equipped with Hamamatsu photo tubes as devices for light
to signal conversion. Eight thousand R7899-20 tubes are used for the
electromagnetic and hadronic calorimeters and two hundred 64 channels
multi-anode R7600 -00-M64 for Scintillator-Pad/Preshower detectors. The
main aim of the calorimeter light emitting diode (LED) monitoring system is to
monitor the PMT gain in time of data taking. The other important role of the
system will be during the detector commissioning and testing in the LHC
machine stops for PMT, cables and FE board tests and relative time alignment.
Each LED of the system illuminates up to 40 tubes and total amount of the
monitoring channels is about 700.
PIN
amplifie
r
PM
T
Phototube Parameters:
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The aim of the LHCb experiment is to fully investigate
CP violation in the Bd and Bs systems,
and to possibly reveal new physics beyond the Standard model.
LED driver with PIN amplifier
board
Number of dynodes: 10
Supply voltage: 1800 V max
Average Anode Current: 0.1 mA max
Quantum Efficiency: 15 % at 520 nm
Current Amplification: 106
Dark Current: 2.5 nA
Time Response: 2.4 ns
Pulse Linearity:+- 2 %
Pulse shapes of the PMT and PIN
signals from LED flash and PMT 50 GeV
particles.
For LED light stability
monitoring the PIN diode
is used. The PIN diode
signal after amplification
is sent to the FE
electronics board.
50 Gev pions
Electronics of LED Monitoring System
1. LED monitoring System Overview
CROC
LEDTSB
2. LED driver and intensity control
LED
The LED intensity control
voltage 3V - 12V
1
Front-End Crate
SPECS
slave
The LED intensity signal distribution board consists of the mother card and
four types of the mezzanine board:
 SPECS slave for interconnection with the LHCb ECS system.
 Control Logic board for interface between the SPECS slave and
others functional parts of Distribution board.
 HV control signal generation mezzanine.
 LED control signal generation mezzanine
TL072CD
LED driver Simplified circuit diagram
TTCrx
15 ns
Air transformer
Bchannel
8
Driver
Shaping
and overshot
circuit
Fast
Shaper
EL7212
"Flashing" pulse
LVDS levels
CLK
Time alignment
circuits
PIN with
Amplifier
2
PMT
6
Inner
Middle
Outer
5
LED
The LED monitoring consists of three
functional parts:
 Subsystem for a LED intensity
control for variation of the LED
intensity across a wide range
includes 40 boards.
 12 9U –VME bards for a LED
triggering pulse control and
distribution placed into the
front-end crates.
 700 of the LED drivers with LV
power distribution.
4
3
HV_LED_DAC
SPECS
System Overview
LED intensity control board
OA
FEBs
Specification:
 Precision of the PMT gain monitoring is about 0.3 %.
Individual time setting for each LED in range of 400 ns with 1 ns step.
PIN diode with amplifier is used for monitoring the LED stability itself.
Control Logic FPGA is placed on a mezzanine card and equipped with radiation
tolerant ACTEL pro-ASIC chip APA300.
Memory of the scanning algorithm FPGA with 64 patterns of the output trigger
signals allows perform all needed sequences for LED flashing.
The calorimeter monitoring system is linked to the LHCb ECS system by the SPECS
serial bus (developed in LAL).
ACT Logic
DS92LV010A
Produce LED signal in a wide intensity range with pulse shape similar the
particle response.
Peculiarities: 1) Edge triggering circuit with fast pulse shaper on the board;
2) Decoupling by air transformer
LEDTSB
3. LEDTSB – 64 channels LED triggering board
Scanning Algorithm
Memory
LED trigger pulse
Channel Mask
1
Coarse
Clk
Phase
Shifter
Delay
0 - 15 ckl
Back Plane
of FE crate
Control Logic
ACTEL FPGA
Broadcast
Command
Decoder
BCALIB[3..0]
SPECS Bus
64
Clk
Phase
Shifter
Parallel
Bus [16..0]
Clk
Phase
Shifter
4 channels
TDC
18
I2C
Signal
Shaper
32
33
34
Signal
Shaper
Clk
Phase
Shifter
16
17
Signal
Shaper
Signal
Shaper
SPECS slave
Mezzanine
Broadcast
commands
from
TTCrx
2
Signal
Shaper
AND
Coarse
Delay
0 - 15 ckl
1
Signal
Shaper
Signal
Shaper
48
49
50
Signal
Shaper
40 MHz ClkBlock diagram of the LED triggering signal distribution
board
Main changes of LEDTSB specification:
Each of 64 channels of LEDTSB is delayed Calibration
signal in range up to 400 ns with 1 ns step. There is no a
channel grouping now.
12.5 ns coarse delay step in range of 5 bits is
implemented, that allows exclude a synchronization
problem when CLK and calibration signal edges close to
each other.
Four TDC’s are added on the board for calibration and
test purpose.
Firmware for APA300 ACTEL FPGA has been
developed and tested.
64
1-4
LVDS
64 output channels of the LEDTSB board is divided on four group
with an individual Coarse delay up to 15 clock cycles with a time
step of 25 ns.
Each output channel is equipped with the shaper for synchronization
with Clock and generation a pulse of 50 ns width.
Detector quality monitoring & Integration into the Experiment Control System (ECS)
1. Monitoring System performance
2. ECS Software for control of the LED monitoring system
LED signal scanned shapes of the HCAL module
Typical LED and PMT stability
ADC (cnt)
Normalized amplitude
8 channels of
Crate_22 (outer)
and
Each point corresponds of the mean value
of PM amplitude for 200 events
Normalized amplitude
8 channels of
Crate_23 (inner)
Eight tubes stability
< +- 0.1 %
Eight LEDs stability measured by PIN
Time (ns)
< +- 0.4 %
Time (Hour)
Performance:
 PMT gain monitoring with precision less then 0.3 %;
 LED stability monitoring by a PIN diode with precision of
0.1 %;
 Online visualization of the calorimeters LED response;
 LED monitoring system is precise tool for the detector
performance study during commissioning and experiment
running time.
 Time scan technique is used for a
correct time adjustment of the LED
monitoring system and checking an
inter-crate synchronization.
 For doing the detector time alignment the
automated process has been implemented to
scan the LED delay from PVSS and collect
data by DAQ (increment step by step the 1 ns
delay of the LEDTSB).
 Precision and stability of the signal arriving
time measurement is about of 0.3 ns.
RMS = 1.16 ns
Time (ns)
ADC (cnt)
1%
Time (min)
PVSSII panels for LED
monitoring system
Device Unit panel of the LEDTSB triggering pulse
sequence configuration
PMT Stabilizing Time of about 15 min
HCAL module 5 normalized
ADC response vs time after
HV ON. 16 Channels
Device Unit panel of the LEDTSB delay
triggering pulse configuration
Specification:
LHCb's Experiment Control System is in charge of
the configuration, control and monitoring of all the
components of the online system. This includes all
devices in the areas of: data acquisition, detector
control (ex slow controls), trigger, timing and the
interaction with the outside world.
The control framework of the LHCb is based on a
SCADA (Supervisory Control and Data Acquisition)
system called PVSSII. Which provides the
following main components and tools:
•A run time database
•Archiving
•Alarm Generation & Handling
•A Graphical Editor
•A Scripting Language
•A Graphical Parameterization tool
Time and amplitude distributions of the PMT
response on LED for HCAL A side.
Control and monitoring parameters:
The LEDTSB and LED intencity boards configuring
is performed by standard FSM way. In the same
time to prepare or modify a recipe one needs a
mechanism to update a recipe content. The LEDTSB
half Configuration panel allows to load new values
from the configuration files or from the dedicated
CALO Data Base. The LEDTSB parameters could be
modified and with using the expert LEDTSB panels
too. After updating the recipe content one can save
the recipe with specified name.
Panel of the HCAL LED intensity configuration