1. Mentor: Chris Kenney 12 August 2010
Research and Development of Silicon Detectors for High Energy Physics and X-Ray Spectrometry
ATLAS, CMS and CXI
Emily R. Brown
Mentor: Chris Kenney 12 August 2010

2. 3-D Pixel Detectors
Electrodes bored through entire wafer vs. planar technologies where they aren’t
Are more difficult to produce than planar detectors
Higher resistance to radiation, faster
Planar detector
3-D detector
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3. LHC Experiments CMS and ATLAS 2 of 6 experiments on the LHC at CERN
-General detectors looking for various physical phenomena
including but not limited to: searching for the Higgs Boson,
evidence of dark energy, SUSY
-Both are roughly similar in design as well as purpose
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4. Inner Pixel Detector
Precise semiconducting silicon pixel detector to track
charged particles and record their energies
Indium bump-bonding
Silicon sensor – initially detects particles, FE processes info from sensor, amplifies signal, MCC then combines individual events, further processes info
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5. SINTEF Problems
ATLAS Chips*
CMS Chips**
Large leakage currents have been recorded after bump-bonding and dicing of ATLAS chips made at SINTEF
Could be from Cu in the metal used for bump-bonding, something with the dicing process, or packaging and handling process
Data above taken after bumps were applied but before dicing
*Angela Kok et. al SINTEF - Oslo, Norway
**E. Alagoz et. al Purdue University, Fermilah
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6. ATLAS vs. CMS
Wafer tested was not diced, and had no copper bumps added
ATLAS chips showed lower leakage current than the CMS chips
current is averaged over the three pixels where data was taken on the chip
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7. Conclusions
The new data is basically completely different from data from SINTEF
- ATLAS chips performed better than CMS, so it may not be something about the
packaging or intrinsic geometry of the two
- Argues against copper as cause
- Argues against dicing as cause
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8. CXI Detector
Will be in LCLS hutch to use short, hard x-ray pulses to image nanoparticles, study x-ray matter interactions, individual biological molecules and more
Silicon detector diode
2 ASIC read-out chips
2-D ASIC read out chips + 1 sensor diode + 1 analog PCB provides power, voltage, grounding, controls interface=carrier board
2 carrier boards +Al strong-back w/cooling feet= 1 module
4 modules = full detector
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9. X-Ray Fluorescence
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10. One quadrant of CXI detector
CXI Beamline Setup
Metal foil
One quadrant of CXI detector
Detector box
Data taken with foils of Cu, Se, and Mo which emit photons of energies 8, 11 and 17 keV
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11. Mo (17.4 keV) 450 μS Pixel energy (ADU) vs. count histogram of ASICs
An Al plate was added to the front to block lower energy photons, lower noise
Very preliminary, simplistic analysis
2 ASICs are not like the others
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12. Mo (17.4 keV) 450 μS, high gain 0 photon Peak Single photon peak
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13. Cu (8 keV) 12 μS, high gain
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14. Se (11 keV) 24 μS, high gain
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15. Cu Low Gain Integration Curve
- In low gain dynamic range about photons
ADU
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16. Se Low Gain Integration Curve
ADU
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17. Mo Low Gain Integration Curve
ADU
CS Pad/CXI Detector
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18. ALS Testing Preliminary Conclusions
Dynamic range within design specifications
Data looks reasonably linear
14 out of 16 ASICs worked
Successfully assembled and operated full quadrant with four working 2x2 modules
Data should provide calibration of all pixels with further analysis
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19. Acknowledgements Chris Kenney for being an outstanding mentor
John Morse and Stevan Veljovic for being an awesome research group at the ALS and being a great support
Steve Rock and the SULI staff for overall wonderful support
The DOE for funding and organizing SULI