STFC Technology

XH Germanium Microstrip Detectorfor EDAS.

Janet Groves /Jon HeadspithSTFC Daresbury Laboratory

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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

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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

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-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

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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

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2.0E-001

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Io/It

Strip number

Io/It: It fixed, Io varying

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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)

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% IN

L

dyna

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rang

e (s

cale

d to

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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

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raw

cou

nts

strip number

Slit width vs bias voltage

50V

55V

60V

65V

20V

25V

30V

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40V

45V

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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

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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

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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

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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

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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

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-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