1 european synchrotron radiation facility, grenoble, 38043, france

X-Ray Beam Monitoring Tests with Single Crystal
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1st ADAMAS Workshop 20121217-18 (edited PDF version) John Morse, ESRF Grenoble
1European Synchrotron Radiation Facility, Grenoble, 38043, France
2Deutsches Elektronen-Synchrotron, Hamburg, 22607, Germany
3Synchrotron Soleil, L'Orme des Merisiers -Saint Aubin, 91192, France
4Commissariat à l'Energie Atomique …, Gif s/Yvette, 91191, France
5Dromedar d.o.o., abnica, 4209, Slovenia
6GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, 64220, Germany
7Instrumentation Division, Brookhaven National Laboratory, Upton, NY, USA
J Morse1, M Salomé1, K Detlefs1
H Graafsma2
K Desjardins3
M Pomorski4
B Solar5
E Berdermann6
J Smedley7

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1. Synchrotrons and X-ray beam monitoring needs:
why diamond? why single crystal?
CVD single crystal diamond bulk- and surface- challenges
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5. 'superthinning’ project
6. Conclusions / status
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Now (2012) about 50 major X-ray synchrotrons in the world…
sources of infra-red to MeV photon beams, but main interest 1 ~ 100keV
the big three, commissioned early 1990's…
synchrotron sources:
ESRF-Grenoble, France
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J-L Revol, ESRF (ASD)

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3rd generation synchrotron beamlines
ΔE/E ~10 -4
flux on sample

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X-ray beamline monitoring goals
but beam powers to 100Wmm-2 (C-W) in undulator ‘white’ beams:
heat load → ONLY possible with diamond
accuracy & linearity requirement typically ≤ 1% (sometimes <0.01% ratiometric)
Intensity:
NINA upgrade beamline, nanofocusing → 10nm beam on sample
measurements ~dc (thermal drifts) to ~ 1kHz (acoustic vibrations)
Position
Timing:
absorption, coherence loss, scattering
lifetime >months under ionizing radiation loads to >104 Gray/sec
device…
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why diamond ?
Z = 6 → low X-ray absorption by photoelectric effect … ~8-fold less than silicon for 10keV X-rays
5.5eV bandgap
→ ‘zero’ leakage current at room temperature and at high E-fields
→ nanosec pulse response times
→ insensitive to ambient light, (λc ~ 215nm )
- ‘all diamond’ devices are (X-ray) radiation hard --no atomic displacement damage
extreme thermal conductivity:
diamond ~2000 Wm-1 °K-1 at 273°K , cf. silicon ~150
…at energies >20keV, short range of Compton-electrons
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high purity diamond plate ~10…100µm thick
metal surface electrical contacts ~100nm thick ( e.g. Al, Pt, W)
externally applied bias field 0.5 ~5 Vµm-1
quadrant diamond X-ray beam monitor: principle
photocurrent readout of beam position and intensity → simple, compact devices
photocharge drifts for ~ nanosecond in applied E field to electrodes
charge cloud lateral thermal diffusion ~10µm
→ induced signals can be measured with 'integrating'
electrometer (charge), or drift current pulses observed directly (wideband)
…beam 'center of gravity' determined by interpolation
surface
contact
beam
DIAMOND
directly intercepting beam, diamond bulk acts as solid state ‘ionization chamber’
electron thermalization range a few µm for <20keV X-rays

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Polycrystalline:
& signal response lag
XBIC: signal current map made from x, y raster scan of sample with a ~7keV micron-focused X-ray beam
LIST-CEA Saclay data (ESRF ID21)
but
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& signal response lag

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SLS MX beam 15 x 100µm2, 1.3 x 1012 ph/sec at 12keV
data Ralf Menk, 2006: polycrystalline ~10µm thick, grown on Si substrate by Diamond Materials GmbH, Freiburg, contacts fabricated at PSI Nanofab (?)
polycrystalline diamond: trapping and signal lag
signal decay after beam cut off
Charge collection efficiency ~1…10%,
variable (prompt + detrapped components) with applied E field 1…5 V/µm,
10 sec

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J. Keister and J. Smedley, NIM A 606, (2009), 7
electrical responsivity with X-ray energy
responsivity
(no field dependence observed)
caused by incomplete carrier collection for near surface absorption

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Linearity at high currents, single crystal diamond with Pt electrodes
(measurements at BNL NSLS-X28C white beam, absorbed power density up to 20 Wmm-2)
signal linearity with beam flux
1.E
Gas ion chamber calibration
J. Synch. Rad 17, (2010)
ESRF ID21 microbeam, 7keV
at ESRF, signal linearity observed over range ~10pA to >10µA
(monochromatic beams, 7 - 20 keV data)
→ operation in linear mode shown over
total >10 orders magnitude
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exploits diffusion splitting (~10µm) of charge
between A, B, C, D contacts of quadrant motif
→ difference/sum of currents A, B, C, D
gives beam 'centre of gravity’ *
→ sum of currents gives beam intensity
*requires high signal/noise !

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position measurement: resistive contacts
first device used in
ESRF & Soleil beam tests ~2009
signal current is shared between edge strip electrodes as ratio of resistances through
resistive contact
position sensitivity independent of
slower response (RC ~µsec)

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quadrant designs: contact fabrication
-multiple designs on single mask;
-electrode features to < 1µm
post-clean handling
ESRF-DESY-OSU XBPM and microdosimetry mask set , 2010
~100nm Al contacts on
30 and 100µm diamonds

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single crystal I-V response in X-ray beam
ESRF ID21 beam ~0.6x1.5µm2, ~4x109ph/sec at 7.2keV,
cross polarizer-selected e6 plates, two-side ion beam etched to final 100µm thickness,
100nm Al sputtered contacts using lift off lithogaphy (OSU-Kagan, 2010)
full charge collection for >10V bias (0.1Vµm-1)
dark leakage current <0.1pA (measurement sensitivity limit) at 200V bias
no hotspot defects found over 7mm2 contact areas for 3/3 preselected samples tested
calibration relative to silicon diode
→ εDiamond = 13.05 +/-0.2 eV/e-h pair

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position response of diamond quadrant devices
For large beamsize (> 50µm), device ‘crossover response’ is simply the line integral across the beam intensity profile
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isolation gap ~120µm
…beam focused <1µm
For a small beam (< 5µm), crossover response is ~independent of beam size:
convolution of

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beamline tests : position timescan and ‘vibrations’,
ESRF ID09B, single bunch mode (355kHz)
charge generated in diamond ~ 0.1pC/pulse
currents measured by Keithley 485 electrometers
(10Hz BW, mean current measured ~10µA/contact)
390um thick diamond sample ‘S361-1’ with TiW quadrant contacts inserted before final slitbox, pink undulator beam peaking at 20keV
4.4 hours

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compact diamond mounting
IBM-etched e6 single crystals 4.2 x 4.2mm2, thicknesses 30 & 100µm
Rogers multilayer PCB,
microcoax wire leadouts
guard-ringed direct PCB
homogeneous response map
<0.1pA leakage current at 2Vµm-1
vertical streaks are from beam Io
normalization errors during scan
sample x,y piezo stage

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quadrant device, electrometer readout: time scans
ESRF ID21 FZP microfocus beam tracking 1sec/point:
vertical beam jumps on synchrotron e-beam refills
X-ray flux ~108 ph/sec at 7keV (FZP optic):
~ 20fC in diamond per X ray bunch
~ 10nA ‘dc equivalent’ signal current
2010 data, 4x109ph/sec at 7.2keV (FZP → K-B mirror)
14(18)nm vertical(horizontal), 1sec integration
33(48)nm, 0,1 sec integration
σ =13.3nm
1sec V-F
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ID22 nanofocus beamline: stability measurements
5-6 Sept 2012:
23:00, successive time scans:
red data: diamond axially displaced 5mm
17keV, flux 2.5x 109 ph/sec
25µm
x
x
x

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ID22 nanofocus beamline: stability measurements
short term vertical and horizontal stabilities
17keV, flux 5.0 x 109 ph/sec
(16 bunch mode)
beam absorption in diamond 1.8% (~70% via photoelectric effect)
measured quadrant currents sum <i > 13nA (ESRF 16 bunch mode, peak pulse currents ~2µA)
for photoelectric absorption,
i = x Exray / ε (Amps) = absorbed X-ray flux;
EX-ray = photon energy (eV)
quasi-linear crossover
10nm steps clearly visible
2.5nm rms
3.9nm rms

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‘resistive contact’ BPMs
40µm e6 plate, with sputtered diamond-like carbon (DLC) contacts (CEA-LIST, M. Pomorski),
ESRF-ID06 beam test:
long term radiation, temperature stability…?
DLC resistive layer
metal collecting electrodes
DLC resistive layer
intrinsic diamond slab
DLC resistive layer
(~0.5µA measured photocurrents)
non-injecting contact

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Position noise of first device tested at ESRF measured was limited by the 20kΩ resistance of the DLC contacts (electrometer input voltage noise driven currents)
new device installed at ID06 June 2012, 265µm thick, 170-200kΩ resistance contacts
resistive contact BPM: device #2 at ESRF-ID06
PCB mounted over hole and electrodes connected by Ag loaded thermoplastic
shadow-mask Au electrodes over full-surface DLC
signal current reaches a well defined plateau corresponding to complete photo-charge collection.
excess signal current and noise seen with >100V 'negative' bias
-->local diamond bulk defect(s)

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device linearity across entire 2mm spacing between the gold line contacts
~zero horizontal-vertical crosstalk
(orientation alignment errors?)
performance, device #2 at ESRF-ID06
beam 12keV, 1.3x 1013ph/sec, ~25x25µm2
x,y mesh plot shows uniform response over most of the 2x2 mm2 active area: no local defects.

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duo-lateral Resistive Electrode, position resolutions
σ = 258nm
device #1, 20 k contacts, 40 µm thick diamond, S/N ~104 (electrometer offset induced noise limit)
active area 2 x 2 mm2, 100msec integrations
[µm]
[µm]
ID06
1 M contacts, 300µm thick diamond, S/N ~105, active area 2.5 x 2.5 mm2, 100msec integrations
σ = 27nm
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narrowband RF readout: Libera Brilliance
'rotating' crossbar RF switch removes electronic drift between A,B,C,D input channels
~500 systems installed at ESRF + DESY
for electron orbit stabilization using capacitive pick-up buttons
analog stage: SAW narrowband tuned filter (352MHz ESRF, 500MHz DESY)
digital sampling at 110MHz, FPGA digital filtering → output data stream ~130ksample/sec
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over fast network
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narrowband RF readout, first tests
Quadrant electrode device first test at DESY-DORIS F1 (white bending magnet, Al filtered beam
!! with Libera brilliance system, measure 'narrowband' (~5MHz BW ) power at 500MHz center frequency
→ only measure ‘ fast drift’ signal components
signal vs. detector bias
550V
217V
138V
May 2012 monochromatic beam tests at DESY P11 with 100µm thick plate
higher field, thinner plate
→ shorter transit times ( <2ns )
electrode ground bounce crosstalk

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Libera dynamic position response
first test at DESY Doris synchrotron white beam (filtered bending magnet F4)
stability timescan (Libera ADC buffer data, 130KHz readout digital sampling-averages)
J. Morse, B. Solar and H. Graafsma, J. Synchrotron Rad. 17, 456464 (2010)
position noise includes real beam-sensor movements
µm
µm
in
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RF readout tests DESY Petra P11 (May 2012)
Tests of series of 8 quadrant BPMs (OSU- and INEX-fabricated Al electrodes)
beam vibrations measured 30m from monochromator with bad LN cooling turbulence
beam
~ 50x100µm2
responses, Libera data (sum map)
Q1
Q2
Q3
Q4
time (secs)
BPM 1 BPM2
diamond BPM-1
diamond BPM-2

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Superthinned diamond membrane beam monitors
40µm thick plate shows significant trapping
– I-V plot with X-ray beam shows no plateau region …
…but 7µm membrane area has a good I-V plateau ,
i.e. bulk trapping in membrane is at ‘acceptable’ level
fast response and no polarization effects seen
can we use material with ~ppm N impurity ??
DDK scaife-polished optical grade CVD single crystal
(optical grade material!)
cental area thickness ~3µm
ceramic mounting/wire bonding
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conclusions / status / future:
quality of CVD single crystal material --threading dislocation clusters-- remains a serious limit on
device yield (bad samples shows high dark signal currents and local signal ‘gain’ effects…)
Element Six ‘electronic grade’ samples have not improved over past ~7 years
→ selection of material still necessary to avoid local 'hotspots'
for intensity and position measurements, ‘proof of principle’ now well established by several groups
using quadrant devices, with electrometer or RF signal readout approaches
ongoing work:
- testing / deployment of devices: electrometer readout at ESRF; Soleil… RF readout at Petra; NSLS-BNL
- investigating commerical fabrication (INEX; Micron; …) for series production of 'standard' device(s)
and sourcing of superthin plates <10µm by deep dry etching
- robust contacts and devices: - DLC variants for resistive contacts
- boron doped CVD overgrowth
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Thank-you for your attention
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1 european synchrotron radiation facility, grenoble, 38043, france

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