Pixel telescope test in STAR at RHIC

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Pixel telescope test in STAR at RHIC

• Xiangming Sun

Lawrence Berkeley National Laboratory
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Motivation and Outline

• Test MAPS technology in STAR (heavy ion
  collision) environment

Hardware setup Installation in RHIC STAR Test
result Conclusion
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Hardware setup-MAPS chip
Monolithic Active Pixel SenorMimostar2 Based
on standard CMOS technology. Developed by IPHC(
http//iphc.in2p3.fr/) Chip size
0.56mm0.51mm Pixel number 128128 pixels,
Pixel size 30um30um Integration time 1.69
ms Work frequency 50MHZ Output type Analogy
output.
functional view of test chip Two subframe
consist of two different type of charge
collecting diodes standard and radiation
tolerance. for detail http//www.lbnl.leog.org/rd
o/index.html To make chip work, readout system is
needed
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Hardware setup-ideal data chain
Analogy signal from MimoStar2 is converted to
12bit digital signal. After correlated double
sampling, 12bit the data becomes 9bit. After
cluster finder, cluster address is reconstructed
based on 9bit data. cluster addresses are built
into event in event builder. Event is transmitted
by DDL statemachine by optical fiber to Linux Daq
PC Need to be realized in hardware
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Hardware setup-readout
MOTHER BOARD
DAUGHTER CARD
3 MimoStar2 chips telescope
Data flow
Control PC (Win)
RORC SIU
Acquisition Server (Linux)
ADC locates in daughter card FPGA in daughter
card implements CDS, cluster finder, event
builder. FPGA in stratix board implements DDL
statemachine. Chip alignment and optimal cut for
cluster finder are unknown Need to be tested on
some known beam
STRATIX BOARD
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Before Installation in RHIC STAR-ALS
1.2 GeV electrons at the ALS (http//www-als.lbl.g
ov/) The noise peak and signal peak are pretty
clear Two type of diodes works well
Efficiency vs accidental rate are obtained from
ALS beam test The optimal cut in cluster finder
and chip alignment is got base on this test
Ready to go to RHIC STAR
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Installation in RHIC STAR
Chip position
Electronics box
Telescope head is put under beam 5cm and 145cm
from interaction region (high particle flux and
possibility to do tracking ) Electronic box
locate on the endcap where submerging in magnetic
field. Stuff in electronic box daughter card,
mother board, stratix board and RORC SIU Lets
see it still work or not
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Test result
Clusters are clear in full frame data (directly
comes from ADC)
Measured charged particle flux was 3.9 per
sensor (1.7 µs integration time, L8?1026
cm-2s-1 ), which agrees with calculation. Noise
level of system in the STAR environment was 7.48
ADC counts, comparable to laboratory and ALS
measurements. DAQ for the telescope is
integrated with STAR Trigger. Events delivered in
the way STAR will upgrade to. Radiation dose
325 rad over running time. 3 hot pixel is found
per chip averagely Three chips, how about
tracking?
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Test result
Using clusters in 3 chips built track. Background
is obtained by the run in which two beams pass
each other without collision
Angle between source particle and background
Experiment 0.0331479 Expected 0.0344828
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Conclusion

• MAPS chip can work in heavy ion environment
  nothing weird happens
• Electronic supporting chip can work in about 0.5T
  magnetic field 3 weeks continuing work time.

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Thank you for your time