Post on 26-Jul-2020
STFC Technology
XH Germanium Microstrip Detectorfor EDAS.
Janet Groves /Jon HeadspithSTFC Daresbury Laboratory
2
Slide titleOutline
• Brief History of EDXAS detectors at STFC– Photodiode array (PDA)– Prototype Si microstrip– XCHIP– XSTRIP
• XH– Technical details– Experimental results
• Developements
PDA
• 512/1024 strips– Hamamatsu and Reticon
devices• 1ms frame rates• Efficiency poor• Radiation damage
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Slide titlePrototype Si microstrip
• Building on the Si microstrip technology and the MX4 readout ASICs implemented in particle phyisics detectors
• Prove that a system could be developed.
Comparison of stepped and silicon microstrip EDE data for 5 micron nickel foil
0
0.2
0.4
0.6
0.8
1
1.2
8300 8350 8400 8450 8500 8550 8600 8650
Energy (eV)
Abs
orbt
ion
(arb
uni
ts)
Io raw
Io Kapton
Stepped data
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Slide titleXCHIP/X2CHIP
The XCHIP is: 128-channel integration amplifier array with data storageand multiplexed outputs• Data storage – allows simultaneous readout and integration• Multiplexing allows reduction of 128 channels to 4 (or 1) output node• Integration time ~1μs to ~1s• Feedback capacitor 2pF or 10pF• Maximum charge 15pC positive, 10pC negative (for 10pF feedback)• Gain -500mV/pC (2pF) or -100 mV/pC (10pF)• Noise at output <50 mV rms• Non-linearity <0.1% over +10pC dynamic range• Output settling 200ns (to within 0.1mV of final value)
High frame rates and high linearity for the XH andXSTRIP detectors are accomplished by using customdesigned ASIC frontend the XCHIP
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Slide titleXCHIP linearity
For EDXAS the linearity is everything
XSTRIP
XSTRIP on ID24
500μm thick Si detector1024 strips, 25μmpitch
8 XCHIPs providing the parallel readout
32 channel DAQ system
XH
Worlds first 1024 strip 50um pitch Ge detector
Designed to address-:Detection Efficiency.Radiation Damage.
XH on ID24
Ge Sensor
a‐GeAl
Ge (p)
B implantAlBias
Outer guard ring Inner guard ring
XH detector headCold plate
Thermally isolated readout circuit (230k)
32 channel DAC (offset control)
LVDS control signal inputs
Ceramic thermal break
Ge sensor (105k)
X2CHIP readout ASICs (x8)
32 Buffer amplifiers
Thermal control via
•PT100
•Power Resistors
XH DAQ
• PC Based• What we have now:
– PC running XP, hosting– 32 ADC channels, 14 bit 10MHz (running at 4.16MHz)– 2 large Xilinx FPGA carrying out data accumulation– 2 DSP processors – acting as host interface processors
• DAQ specific– Readout in 10us– Frame storage 20us – 1700 frames
STFC Technology
-1900000
-1880000-1860000
-1840000-1820000
-1800000
-1780000-1760000
-1740000-1720000
-17000000 200 400 600 800 1000
-54.06V_dark1_10us -54.07V_dark1_1000us
Radiation tolerance: Dark current baseline
Data taken prior to start of experimental beamtime on ESRF ID24Average dark current ~ 26.6pA
High leakage strips
Faulty readout circuit
STFC Technology
Radiation tolerance: 1 week of beamtime
-1900000-1880000-1860000-1840000-1820000-1800000-1780000-1760000-1740000-1720000-1700000
0 200 400 600 800 1000
Dark13_10_50.02V Dark13_1000_50.01V
High leakage strips
Faulty readout circuit
Data taken at completion of experimental beamtime on ESRF ID24Average dark current ~ 29.9pA
0.0E+000
2.0E-001
4.0E-001
6.0E-001
8.0E-001
1.0E+000
350 450 550 650 750 850
Io/It
Strip number
Io/It: It fixed, Io varying
-500000
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
0 200 400 600 800 1000
Inte
nsity
(arb
)
strip number
Io, It data at various integration timesIo-Iod(220us)It-Itd(220us)Io-Iod(200us)Io-Iod(180us)Io-Iod(160us)Io-Iod(140us)Io-Iod(120us)Io-Iod(100us)Io-Iod(80us)Io-Iod(60us)Io-Iod(40us)Io-Iod(20us)Io-Iod(10us)Io-Iod(5us)Io-Iod(1us)
-0.1
-0.05
0
0.05
0.1
0.15
0
0.2
0.4
0.6
0.8
1
0 50 100 150 200
% IN
L
dyna
mic
rang
e (s
cale
d to
1)
integration time (us)
Linearity Io/It varying Io
Sum(350:850) %error
STFC Technology
System Linearity
Linearity data taken from measurement of ESRF-ID24 undulator profile
-1900000
-1700000
-1500000
-1300000
-1100000
-900000
-700000
-500000
-300000661 662 663 664 665 666 667 668 669 670 671
raw
cou
nts
strip number
Slit width vs bias voltage
50V
55V
60V
65V
20V
25V
30V
35V
40V
45V
70V
75V
STFC Technology
Spatial resolution
At a bias of => 50V • spatial resolution ~ 3 strips FWHM LSF
At a bias of 50V•minimised dark current noise
Increasing bias improves LSF
Increasing bias increase the dark current contribution
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Slide titleSpatial resolution - Rh foil
-1
-0.5
0
0.5
1
1.5
2
23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 24
Ln Io
/It
E (keV)
Rh Foil comparison
BM29 Stepped scan SRS9.3 ESRFID24
-0.2
0.3
0.8
1.3
1.8
2.3
350 370 390 410 430 450 470 490
Ln ((
Io-Io
d)/(I
t-Itd
))
strip number
Rh foil, accumulated readouts at low and high rates
Scan=1, lowrate
Scan=1, highrate
Scan=10, lowrate
Scan=10, highrate
Scan=100, lowrate
Scan=100, highrate
Scan=1000, lowrate
Scan=1000, highrate
STFC Technology
More Spatial resolution- Rh foil
Low rate : I0=13μs, It 35μsHigh rate : I0=0.6μs, It 1.6μs
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Slide titleSingle bunch
3
3.5
4
4.5
5
5.5
6
-20
0
20
40
60
80
100
400 450 500 550 600 650 700 750 800
Ln Io
/It
It-Itd
(ful
l dyn
amic
rang
e =
4095
)
strip number
Single bunch Fe foil
It-Itd
Ln((Io-Iod)/(It-Itd))
~520 ph
~120 ph
ESRF 4 bunch mode, 700ns gaps, capture a single bunch
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Slide titleMore bunches
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
400 450 500 550 600 650 700 750 800
Ln(Io
/It) +
sca
ling
strip number
Fe foil for various numbers of bunches
1 bunch
10 bunches
50 bunches
500 bunches
Recording bunches around orbit
-9.4E+08
-9.3E+08
-9.2E+08
-9.1E+08
-9E+08
-8.9E+08
-8.8E+08
-8.7E+08
-8.6E+08-300 200 700 1200 1700 2200 2700
inte
nsity
(arb
)
delay from orbit Clock (ns)
sum of detector data vs orbit delay
Tint500-12 Tinit250-12 Tinit100-12
Developments
• Development with DLS I20• New Ge sensor from LBNL • New readout system for detector being developed by P Coleman-
Smith for the AIDA nuclear physics programme – currently awaiting final project approval– Support up to 2048 strips via 64 ADC channels– FPGA data acquisition system running LINUX with Gbit Ethernet
connectivity .– Increased sampling rate– Support 7.5μs readout and frame storage– Support 65536 frames– Support for integration times <500ns (aiming for 300ns) – readout
time will remain at 7.5μs incurring dead time
Longer term developments
• New XCHIP is designed for high linearity not high speed -Potentially a new XCHIP design that trades off linearity (and signal to noise) specifically for single bunch experiments
• 1536 element Ge – currently the limit of the wafer diameter
• 2048 element Si device
• IO measurement – concurrent I0 would greatly improve data quality. This needs to be addressed.
Acknowledgements – in no particular order!
• LBNLP N Luke, J S Lee, M Annan, W D Goward
• STFCG Salvini, M Kogimtzis, S L Thomas, R Farrow,I Harvey, S Fiddy, G Derbyshire, I Lazarus, P Coleman-Smith, Zhi-Jun Xin
• Southampton UniversityJ Evans, M Tromp
• DLSA Dent, S Diaz-Moreno, T Rayment
• ESRFO Mathon, C Ponchut, S Pascarelli, Mark Newton
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Slide titleScan Showing beam movement on
Id24
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Slide titleEnd
End
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Slide title
Specification
Germanium1024 strips
Silicon1024 strips
50um pitch 25um pitch
5mm Strip length 2.5mm Strip length
1mm Thick 500um Thick
Leakage current<30pA
Leakage current<10pA
100v bias 70v bias
Energy Range5-40Kev Energy Range5-15Kev
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Slide title
• Detection medium• Ge• Number of strips• 1024• Strip pitch• 50mm• Strip length• 5mm• Detector thickness• 1mm• Energy range• 5 - 40keV.• Efficiency @ 30keV
>90% f th h l t