Post on 18-Dec-2015
Quad Module: 200μm ROC• Chip ID 1 – no longer working
due to accidental damage. Bonds will be checked
• Chip ID 3 – not working: no RX signal. Bonds will be checked.
• Chip ID 4 – not wire-bonded yet
• Chip ID 2 – Working: Tuned to 3200e and 1600e thresholds Working Chip
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Chip ID 2 Characterisation• Biased to -100V at room temperature
• Module kept from heating by constant airflow from fan from the side
• Kept from light exposure using dark box
• Leakage current 50nA in complete darkness
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Chip ID 2: Tune to 3200e threshold• Threshold tuned to 3200e
• Best result obtained through standard TDAC-FDAC-TDAC cycle during tuning
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• Initial TDAC tune gave better result but ToT had to be tuned
• Taken sample of pixels here to make scan shorter
Chip ID 2: Tune to 3200e threshold
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• See chip is tuned to ToT ~8 @ ref. charge of 20ke
• Again, best result obtained through TDAC-FDAC-TDAC cycle
Chip ID 2: Tune to 8ToT @ 3200e
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• Initial FDAC tune gave good ToT but altered threshold value considerably
Chip ID 2: Tune to 8ToT @ 3200e
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Noise Occupancy @ 3200e: 10 mill events
• Bias OFF
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• Mask produced for pixels with occupancy over 1,000
• Bias -100V
Noise Occupancy @ 3200e: 10 mill events
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• Mask produced for pixels with occupancy over 1,000
• A number of pixels are shown to be disconnected around the edges
• Will use ROOT macro to ascertain exact number of pixels that are disconnected
3200e Threshold Scan 0V – bump yield
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• Zoom into 120e region• Judging by eye, ~6,500 pixels exhibit noise around 120e giving a
yield of ~25% disconnected pixels
3200e Threshold Scan 0V – bump yield
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Behaviour of Single Chip• Noise plots of single chip (VTT Assembly 15) at threshold of 3200e:
0V 100V
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• Threshold tuned to 1600e• Some pixels remain tuned to
threshold of 3200e • Tuning down was very quickly
done
Chip ID 2: Tune to 1600e threshold
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• ToT not perfect but in correct region.• Could be improved with more
fine-tuning.
Chip ID 2: Tune to 8ToT @ 1600e
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• No discernible peak around 120e
• Compare to biased assembly in next slide
1600e Threshold Scan 0V – bump yield
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• Log Y used to look in detail at noise
• Pixels with highest noise values are on top in occupancy plot
1600e Threshold Scan 0V – bump yield
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• Zoom into top rows of occupancy plot
• Noise in these pixels is >500e
1600e Threshold Scan 0V – bump yield
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• Looking at SCURVES for a sample of pixels
• HOT PIXEL
1600e Threshold Scan 0V SCURVES
Row 4, Column 14:
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• Looking at SCURVES for a sample of pixels
• WELL-BEHAVED PIXEL
1600e Threshold Scan 0V SCURVES
Row 261, Column 31:
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• Looking at SCURVES for a sample of pixels
• SWITCHED-OFF/BROKEN PIXEL
1600e Threshold Scan 0V SCURVES
Row 144, Column 13:
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Summary• Chip 2 can be tuned to threshold of 3200e and 1600e and a ToT
of 8
• ~25% disconnected pixels
• In general, this assembly behaves as a single chip assembly• Nothing to indicate otherwise
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Work yet to do …• Fine-tuning of Chip 2 to threshold of 1600e/ToT=8
• Use ROOT macro to find number of disconnected bumps on Chip 2
• Set-up Sr90 scans – beta particles should penetrate to other side to be detected in PMT for triggering
• Try Am241 scans – HITOR not bonded and it is thought that this is needed for Am241 scans
• Wire-bonding of Chip 4
• Tuning and characterisation of Chip 4
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