Beam Diagnostics

The 18th KEKB Accelerator Review Committee
March 5th, 2013
KEKB Monitor Group
M. Arinaga, J. Flanagan, H. Fukuma, H. Ikeda, H. Ishii,
S. Kanaeda, K. Mori, M. Tejima and M. Tobiyama

Contents• Introduction• Beam Position Monitor System• Bunch Feedback Systems• Photon Monitor System• Misc.
• Construction Plan
• SummaryIntroduction
SystemQuantity
HER

LER

Beam position monitor (BPM)

466

445

Displacement sensor

100

100

Transverse bunch by bunch feedback

1

1

Longitudinal bunch by bunch feedback

DR
84
1

1

Visible light monitor

1

1

X-ray light monitor

1

1

Beamstrahlung monitor

11

Gated measurement

11Tune monitor

11

Loss Monitor

1

200

34

DCCT

1

1

1

Bunch current monitor

1

1

1

Beam Position Monitor System

Beam Position Monitor System
Decisions made after last ARC
1. 70 turn-by-turn BPM detectors out of 270, 35 in each ring, will be installed
for Phase 1.
The detectors will be mainly used for injection tuning.
2. Four medium-band detectors will be installed for Phase 1.
The detectors will be used for measuring orbit variation near local
chromaticity correction sextupoles. No orbit feedback will be applied.
HER : SLYTRE.1, SLYTRE.2
LER : SLYTRP.1, SLYTRP.2
3. Four BPMs will be used for triggering the beam abort if a large horizontal
orbit deviation is observed. The purpose of the monitors is to protect
extraction windows for aborted beams.
4. A monitor measuring longitudinal position/phase of the injected bunch will
be installed.
We are considering the use of commercial Libera based detectors for items 2,
3 and 4 above.

Configuration of main BPM system

Gated TbT

•Super-heterodyne detectors in
KEKB BPM system are also
main detectors in SuperKEKB.
•Detection frequency in LER islowered to 509 MHz due to thechamber cutoff frequency of 989
MHz.

Gated TbT

•Selected 270 BPMs have gatedturn-by-turn monitoring function.

BPM system at Phase 1
Type

Function

Resolution

Repetition

umber ofunits

Narrow-band of
KEKB

Closed orbit
correction, CCC,
optics measurement

3µm

0.25Hz109 (alreadyhave.)New narrow-bandwith 509MHz
detection

As above

2 to 3 µm

0.25Hz133

Gated turn by turnInjection tuning,
optics measurement

50 - 100µm 100kHz

70

Medium-band

Measurement oforbit variation< 2 to 3 µm 10kHz

4

One narrowband detector covers four BPMs.
IP feedback detectors might be tested though they are not needed at Phase 1.

Button electrode and BPM support for the LER•Button electrodeProduction of all electrodes is completed.
The electrodes are being installed on BPM blocks after coating with TiN.
•Diameter : 6mm•Flange type for easy replacement and for removal during TiN coating of
the chamber•Pin-type inner conductor for tight electrical connection..
•BPM block•All BPM blocks connected to LER arc chambers have been made by thevacuum group.

Button electrode

BPM block at wiggler sections

BPM block in arc sections

509 MHz Narrowband Detector•Twenty 509 MHz narrowband detectors have been ordered inthis FY.
•Mass production of 120 units is scheduled in next FY.
Super heterodyne detector with 509MHz detection
MUX 4:1

BPM

VXI module509 MHz Narrowband Detector : Performance (tentative)•Performance of the detectors is being measured at thecompany as part of the production.
1) Ratio SNRs (B/A, C/A, D/A) are larger than 90 dB.
(A, B, C, D : voltages of four electrodes)

Temperature at the measurement: 25deg.

2) Apparent position shift by changing attenuation of thevariable attenuator from 0 to 55dB is about 3 µm p-p.
3) Linearity is better than 0.05% in the voltage range of 1/4 fullscale to full scale.
Channel A
deviation from a line

•Linearity was measured
by changing input power
level with variable andfixed attenuators.
•Attenuation at eachsetting of the attenuators
was calibrated by the fit
to data.
Example of linearity analysis

Gated turn-by-turn detector•Twelve turn-by-turn detectors have been ordered in this FY.
•60 turn-by-turn detectors will be ordered in next FY for Phase 1.
Fast gate•

glitch cancellation circuit
FPGA(Spartan6)

Log amp & ADC

Switch : Hittite GaAs MESFET, DC – 12GHz
Log amp : ADL5513 (AD)ADC : ADS850 (TI)

Fast gate

IP Feedback Detector

Main sources of orbit movement: vibration of quadrupoles closest to IP
Main frequency components: 3, 36, 53Hz (simulation)
Tentative specification for the detector
Resolution < 1 µm
Repetition 5kHz
Bandwidth 1kHzHz
Movement of QC1RP by a simulation (H. Yamaoka)

IP Feedback Detector : Detector

PrototypeµTCA•Down-convert 508.8MHz component tointermediate frequency (IF) of 16.9 MHz
Analog partwith an analog mixer to reduce thedegradation of the SNR by the clock jitterof ADC.
•AD conversion•Digital filters (2 CICs, 1 FIR)
• Position calculation

analogue down converter

Digital part

Digital processor board•The digital part is implemented
in a µTCA board developed forSuperKEKB LLRF system.
•EPICS is embedded in the board.

IP Feedback Detector : Activity in this FY
1) New digital processor board• A new digital processor board developed for LLRF was tested.
• Difference of SINAD among four channels is improved comparing withthe old module.
•
73-taps FIR was implemented to reduce the group delay to 1ms.
A measurement showed that resolution is about 0.1µm after the change of FIR.

new board

old board

Comparison of SINAD between old and new LLRF digital boards.

90
85
80
SR [dB ]2) Improvement of analog parta)Expansion of dynamic range of thedown converter to remove saturationof SINAD.
•
Rearrangement of level distribution
through circuit elements by removing
LNA and using a high P1dB(30dBm)
and high gain(36) IF amp.
b)Phase noise improvement•Replacement of the switching power
unit with a series dropper regulator.
•A new oscillator board for samplingclocks and local signals
Separation of power lines between
analogue and digital parts
Hoping for clock jitter reduction from1.66 ps to 1ps.
The modified circuit will be tested thisspring.

75
70
ch A

65

cb B
60

ch C

55

ch D

50
-60

-50

-40

-30

-20

Input power [dBm]

Saturation of SNR-100

IP Feedback processor unit (µTCA)•Prototype of a feedback processor module has been made.
• Implemented with Matlab/Simulink with systemgenerator (HDL coder) for easy coding.
•Simple PID algorithm is implemented now.
•We are planning a feedback simulation using Cosimulation with Simulink and the ML507 evaluation kit.
•A receiver and a power supply interface will be developedin next FY.
FabricA

SFP

Extension

SFP

GbE server

GTX

GTX

MATLAB/Simlink+Xil
inx System Generator

GTX

GTX
GTX

GTX

from BPM degitalprocessing boards

GTX
FIFO

PLB

Corrector P.S.

FPGA Vertex 5FXT

PPC440DRAM

JTAG

Embedded EPICS

Libera brilliance+ (by Instrumentation Technologies)•We are considering the use of commercial
Libera based detectors for medium banddetectors, orbit interlock modules andlongitudinal phase monitors.

•Three acquisition modes : Turn-by-turn, FA (repetition 10kHz), SA(repetition 10 Hz)•One Libera brilliance+ was purchased and is being tested at laboratory.

Bench test of Libera brilliance+
1) Resolution
horizontal

verticalhorizontal

vertical

0.105 [µm]0.075 [µm]

[μm]

[μm]

(r.m.s.)Measurement of resolution of FA data
horizontal

vertical

[μm]

[μm]

horizontal

vertical

0.310 [µm]0.160 [µm](r.m.s.)Measurement of resolution of Turn by Turn data

The resolution is good enough for the medium-band detector.

2) Interlock latency
LiberaBrilliance+

circuit

Pulse generatorSG
SG output

Interlock

Frequency
divider

oscilloscope

SG Offinterlock

Latency
400±50µs (40 turns ≈ a synchrotron period)
Probably, the latency is not short enough for our purpose .
The assessment by the company shows interlock latency will be reduced to a
few turns by using Turn-by-Turn data if software is modified.

Main work in next FY•Production of 120 509MHz detectors•Production of 60 gated turn by turn detectors•Development of a receiver and power supply interface for IP orbit
feedback.
•Development of a feedback algorism in the IP Feedback processor
unit.
•Order/fabrication of the medium-band detectors, the orbit
interlock modules and the longitudinal phase monitors.
•Design and fabrication of displacement sensors at rotatablesextupoles.
•Purchase of signal cables and so on.
•Schedule of cable connection of BPMs is not decided yet because
it strongly depends on vacuum, magnet and facilities work in thetunnel.

Bunch Feedback Systems

Preparation status• Most of the hardware needed for the SuperKEKB rings (HER,
LER, DR) will be ready by the end of this FY.
– Bunch detection circuits– iGp12 digital filters– Digital QPSK back-end– Temperature monitor systems– Position monitor chambers– Transverse kickers• Longitudinal kickers : still in design stage– High power final amplifiers (Transverse, Longitudinal)– 1.5kW high power attenuators– Circulators, low-pass filters for Longitudinal Kickers– High power cables, bpm cables

(Optional)

New FB monitor using glass-type sealing feedthroughs (all)Move HER Upstream monitor one section downstream to adjust phaseadvance
Add another transverse stripline kicker next to the original one
Prepare better longitudinal kickers for LER. HER is optional.

iGp12s

HER

LER

Bunch detection electronics

Power amplifiers• Transverse power amplifiers– 10k-255MHz Pmax=500W amplifiers
R+K : 10 units ready (2 for spares)– 10k-255MHz Pmax=250W amplifiers(AR250A250, used for KEKB) : 11 units ready– 8 for SuperKEKB MR, 3 for Damping Ring
• Longitudinal power amplifiers– 900MHz-1.8GHz Pmax=500W amplifiers
R+K : 8 units ready
Milmega : 2units ready (for spares)

High power amplifiers
LER
Transverse

LER
Longitudinal

HER
TransverseNext FY
• Fabricate longitudinal kickers for LER• Re-arrange the local control room (FB4) to install new detection
circuits• Cabling work (High power, bpm, temperature monitor)– Installation of vacuum components? (Depends on vacuum
schedule.)• Tuning of the digital circuits (iGp12, iGp8, bunch current
monitors, etc)
– Mainly FPGA firmware• Special monitors related to bunch feedback systems– Pilot bunch excitation using PLL tech. (by iGp12?)– Gated measurement systems (tune, beam-beam kick) using
old BOD?

Photon Monitor System

Photon Monitors• SRM: Synchrotron Radiation Monitor
 Visible light monitor, Interferometer, streak, etc.
 σz, σx (σy)• XRM: X-ray Monitor
 Pinhole, URA mask, etc.
 σy (σx)• LABM: Large Angle Beamstrahlung Monitor SR-like radiation from interaction point (~300-600 nm)
 Can measure relative offsets and size ratios at collision point.
• CSM: Compton-scattering based beam energy monitor
 Brand new subject, collaboration with SLAC under US-Japan
program, and possibly BINP.
 Not much to say about this yet!

SRM: Interferometers
SR Source Bend Parameterεx

S-LER1(BSWFRP)
3.20E-09

S-HER(BSWOLE)
4.60E-09

κ

0.27%

0.24%

εy

8.64E-12

1.10E-11

m

βy

29.98

32.49

m

σy
Beam Energy
Bend effective length
Bend angle
Bend radius ρ
Observation wavelength λ

16.1

18.9

µm

4
0.89
5.04
179.0
4.00E-07
1.0

7
2.90
5.00
580.0
4.00E-07
0.7

GeV
m
mrad
m
m
mrad

0.7
99%

0.7
99%

mrad

Max. Visibility (fringe depth) γmax
Min. measurable beam size σy min

12.8

13.5

µm

SR Opening angle θc (λ)
Slits opening angle D/F

Units
m

•Resolution fundamentally limited by measurement
wavelength and opening angle between slits frombeam (D/F).
•Max. slit separation determined by beam spreadand mechanical considerations.

•Vertical beam size measurement is possible with interferometers, though is near
the limit of the interferometer resolution, and single-shot measurement is notpossible.
•To minimize deformation due to heat load, gold-coated diamond mirrors areunder development.
•28 mm x 18 mm prototype in fabrication now.
•Cavities below optics hut floors in D4 and D8 klystron galleries have been
filled to reduce the amount of floor vibration, which had been a problem during
KEKB operation.
•D4 hut has been expanded to accommodate second optical table and x-ray
monitor readout space.

Diamond mirror
prototypeSRM: Summary Reuse present source bend locations
 LER bend becomes longer, to reduce heat load
 HER remains the same
 Move extraction chambers downstream ~few meters Put mirror in antechamber for reduced impedance Floors under above-ground tunnel components have been reinforced to reduce
vibrations
 Transfer lines will be rebuilt to be better sealed against air flow σz: Streak Camera→OK σx: Interferometer→OK (not single-shot, though) σy: Interferometer Will be difficult to get required resolution
 Not possible to get single-shot (single bunch, single turn) measurements, which willprobably be needed for low-emittance tuning, based on experience at CesrTA.
 However, should be useful for cross-checking with x-ray monitor at larger beam
sizes.

XRM: Coded Aperture Imaging
Technique developed by x-ray astronomers using amask to modulate incoming light. Resulting image
must be deconvolved through mask response(including diffraction and spectral width) toreconstruct object. Open aperture of 50% gives highflux throughput for bunch-by-bunch measurements.
Heat-sensitive and flux-limiting monochromator notneeded.
We need such a wide aperture, wide spectrum
technique for shot-by-shot (single bunch, single turn)measurements.

Uniformly Redundant Array(URA) for x-ray imaging to be
used at SuperKEKB

Source distribution:+
Kirchhoff integral over mask(+ detector response) Detected pattern:

Simulated detector response forvarious beam sizes at
SuperKEKB LERXRM: SuperKEKB x-ray monitor
Xray Source Bend Par. S-LER(BS2FRP.1)
3.20E-09εxκ
0.27%
8.64E-12
εy
50.0
βy
20.8
σy
Beam Energy
4Effective length
0.89
Bend angle
28.0
ρ
31.7
Critical Energy
4.4

S-HER (BS2E.82) Units
4.60E-09
0.24%
1.10E-11
11.5
11.3
7
5.9
55.7
105.9
7.1

m
m
m
µm
GeV
m
mrad
m
keV

 Mask:





HER

59-element, 10 µm/element URA
High-power design 10 µm Au mask
 625 µm Si or CVD diamond substrate Test at CesrTA
 Other patterns, materials under study
Detector: 64-channel, 50 µm InGaAs detector (same as at CesrTA) can beused at first.
 For better detection efficiency at 10-20 keV (SuperKEKB), deeppixel design being developed at SLAC under the US-Japan
program.

•Red points: using 64-pixel detector ofsame type as at CesrTA (Fermionics)•Green points: using detector withimproved photon detection efficiency at
higher x-ray energies (to be developed)LERXRM: Coded Aperture tests at CesrTALow-energy masks:
 Continued study of systematics in analysis of coded aperturedata.
 Coded aperture regularly used for electron-cloud and Intra-Beam
Scattering (IBS) studies.
 Evaluated new designs for low-energy mask, selected one
design (Cornell design) for testing at CesrTA in 2013.
High-energy mask high-power tests:
 Au+Si mask tested at 120% of SuperKEKB SR power load Melted!
 Au+Si mask survived at 100% previously.
 Flaw in heat sink design possible -- will change design for
SuperKEKB.
 Au+CVD (diamond) mask installed for testing in April 2013
 Will use factory-damaged mask for burn test at D Line.
 Will use good mask for imaging test at C Line.

Au+Si mask after 100%
SuperKEKB equivalent power:

Examples of bunch-by-bunch data
(electron-cloud blow-up study data)
Single-shot data average for eachbunch

Au+Si mask after 120%
Factory-damaged Au+CVD
SuperKEKB equivalent power: mask for burn test:

XRM: Coded Aperture tests at ATF2
Data: Dispersion Knob Scans

Simulations

Measured beams of 7.5 µm or less with scanned-pixel measurements
New world record for coded aperture measurements

XRM: Readout development• High-speed readout for SuperKEKB (U. Hawaii)– Evaluated STURM2 motherboard design in lab and at U. Hawaii
XFEL.
– Based on results, have redesigned motherboard layout, especially:• Improved shielding for pre-amp daughter cards• Re-designed detector daughter card for improved signal
impedance.
– New boards designed and laid out, and fabrication started.
• Plan to test at UH XFEL, and ATF2.

Shielded pre-amp daughter card:

New detector daughter card:XRM: Summary
 Source bends upstream of SRM source bends– LER bend is reused KEKB LER bend magnet (at half strength)– HER uses same current arc bend magnet– Some modifications to magnets downstream of source point have beenrequested of magnet group, to accommodate x-ray extraction line.
 σy: Coded Aperture Mask
– Single-shot (single-bunch, single turn) resolution expected to be
sufficient.
– Single-shot mode probably be needed for low-emittance tuning, based on
experience at CesrTA.
 σx: Possible, if single-shot measurements are needed– SRM should work for this in slow integration mode
 Being developed in collaboration with Cornell U., U. Hawaii and SLAC
– Testing different components at CesrTA and ATF2
 Development work continuing on detector and readout

LABM: Large Angle Beamstrahlung Monitor• The radiation of the particles of one beam due to the bending force of the EM
field of the other beam
• Beamstrahlung POLARIZATION at specific azimuthal points provides
information about the beam-beam geometry.

G. Bonvicini

LABM: Layout• 4 viewports and associated 5.6 mm2 mirrors on Beam Pipe
(KEK), at 7-8 mrad w.r.t beam axis
• 4 narrow acceptance telescopes, which count photons in twopolarizations and 4 bands (32 channels total, WSU)
• Build flexible electronics for a variety of beam measurements(Tabruk U. (Saudi Arabia), WSU)
• Be extraction mirror prototype (2 mm x 2.8 mm) and extraction
windows fabricated. (KEK)
Optical channel

Tunnel floor
Optics box

Beamstrahlung Monitor
•
•
•
•
•
•

2012 results (Wayne State U.):First (of two) optics box built and tested.
Second optics box started.
Remote-controlled primary mirror for
optical transfer line built and tested.
24 elbows for optical transfer lines built.
Electronics for readout at SuperKEKB
under development with Tabruk U. (outsideof Nichibei).
Calculations for beam test at Frascati carriedout.

PMT mounts inside optics box

Final optics box

Prototype optics box

Movable mirror

LABM: Extraction mirror prototype (KEK)

Currently in fabrication

Beamstrahlung monitor
Plans for 2013
• At Wayne State:– Complete second optics box– Complete 3 more remotely controlled Primary Mirrors for optical transfer
lines– Build relay line interfaces with accelerator extraction window flange– Precision bench test calibration of all viewports and PMTs of both optics
boxes– Prepare for beam test at Frascati• Design and make optical transfer beam pipes and supports.
• Beam test would start summer 2013, continue 10 months.
– Finalize electronics (collaboration with Tabruk U.)• At KEK:– Finalize design of extraction mirror, make production versions.
– Extraction window flange hardware.

Photon Monitors Schedule• 2013:– SRM• Final mirror prototyping and testing• Extraction chamber design– XRM• Continue heat and imaging tests with high-power optics at CesrTA• Continue Electronics and detector development• Construction of major components of extraction beamline.

– LABM• Construction of second optics box and extraction mirrors.
• Continue electronics readout development• Frascati beam test planned starting in summer, 2013.

– CSM• Investigate design of system with SLAC and BINP.

• At SuperKEKB turn-on (non-collision):– SRM & XRM commissioning and emittance measurements– LABM commissioning and background studies• Sometime soon after (real, non-bakeout) turn-on:– LABM comissioning and collision measurements• Somewhat further ahead:– Compton-scattering-based beam energy monitor

Ｍｉｓｃ．

CT, DCCT• Remodeling the original DCCT in progress– Exchange the old cables– New circuit to allow increase in maximum beam
current from 3 A to 5 A– Tune the step response of DR DCCT if needed.

Loss Monitor• Re-use the sensors (ion chamber and PIN PD) of KEKB.
• Because of recent results of beam loss simulation, we are
studying whether the dynamic range of readout is sufficient or
not, and will redesign it if necessary.
– R&D: next FY– Production: FY2014• If we increase the number of channels, extra cabling isnecessary.

DR Monitor• BPM– Electrode, Detector, Signal cable: ready• FB– Kicker, Amp&filter, FT&cable, Low level: ready• SRM– Extraction mirror, transport line, streak camera, gated camera and opticalelements: ready– extraction mirror chamber : need to consult with vacuum group• DCCT– Remodeling in progress• Loss Monitor– Sensor: Reuse the linac ion chambers– Read-out: FY2014– Cables: ready• Control rack, VME rack, NIM BIN etc. : readyR&D
fabrication, installation

Construction Plan:MR
FY2012
BPM

2013

Displacement censor

More TbT
Local corr. SX

Signal cable
Kicker
Amp&filter
FT&cable
Low level
Photon Monitor

Visible light beam line
Extraction mirror
X-ray beam line
X-ray detector
Beamstrahlung monitor
Compton scattering monitor

Misc.

2015

Electrode
Detector

Bunch feedback

2014

Loss monitor
DCCT
Bunch current monitor
Gated measurement

readout

Construction Plan:DR
FY2012
BPM

2013

2014

2015

Electrode
Detector
Signal cable

Bunch feedback

Kicker
Amp&filter
FT&cable
Low level

Photon Monitor

Visible light beam line

chamber

Extraction mirror
Misc.

Loss monitor

readout

DCCT
Bunch current monitor
Tune monitor

R&D
fabrication

Summary• Upgrade of beam diagnostics system is advancing smoothly. The installation
schedule depends on other components. The tuning of each detector will be
done.
• BPM
– Electrode: ready– Narrowband detector: production in next FY– TbT: production in next FY and after– Mediumband detector: order/fabrication in next FY– Displacement sensor at local chromaticity correction section: design andfabrication in next FY• FB– Most hardware is ready.
– Longitudinal kicker and special monitor (pilot bunch excitation, gatedmeasurement): production in next FY.

• Photon Monitors– SRM: testing the final extraction mirror and design chamber .
– XRM: continue the testing of electronics, detector and construction ofbeam line.
– LABM: continue the readout system and construction of optics box and
extraction mirror.
– CSM: future plan
• DCCT/CT: ready• LM: studying specifications of readout electronics• DR– R&D of LM readout, BCM and Tune meter– Installation time is restricted after DR construction.

SparesX-ray monitor
Plans for 2013
• At Cornell:– Test Au+CVD (diamond) high-energy mask at CesrTA.
• Imaging tests• Burn tests– Test new design of low-energy coded aperture (Cornell design) in 2013 at
CesrTA.
– Continue systematics studies of x-ray optics at CesrTA, and continue using
coded aperture optics for electron-cloud and IBS studies.
• At UH:– Complete fabrication of redesigned 64-channel readout system forSuperKEKB.
– Test 64-channel readout system at UH XFEL and ATF2.
• At SLAC:– Develop new high-energy detector for increased detection efficiency overSuperKEKB’s x-ray spectral range.

SRM: Extraction mirrors•Large incident power a source of heat-load induced deformations•SuperKEKB LER source bend is recycled arc bend, with bending radius twice thatof KEKB source bend.
•Incident power becomes less than that of the KEKB HER, though more thanthat of the KEKB LER.
•HER bend does not change, and incident power becomes a bit higher than that of
the KEKB HER.

Energy(GeV)
Current(A)Bending radius(m)Power(W/mrad)
Distance to mirror (m)Be Mirror width (mm)Total incident power(W)LER (BSWFRP)
SuperKEKB
KEKB
4
3.5
3.6
2
177.4
85.7
72
48
11
11
35
35
161
109

HER (BSWOLE)
SuperKEKB
KEKB
7
8
2.6
1.4
580
580
149
136
13
13
35
35
283
260

The heat deformation was already a great problem at KEKB, sowould like to have a mirror that does not deform as much under
the same heat load: diamond mirrors.

SRM:
Diamond
Mirrors• Monocrystalline diamond:– Being developed by Seki Technotron• 10 mm x 20 mm x 0.5 mm prototype completed.
• 20 mm x 20 mm x 1 mm prototype in fabrication– Surface: 3 µm Au, with thin Cr layer below that.
– Diamond surface is (nearly) a single crystal, so good surface
flatness expected (Ra ~ 2 nm, <~λ/50)– Very good heat conductance and low thermal expansion
coefficient makes apparent change in magnification smaller
than that of Be mirrors used at KEKB:• Berylllium: δmagnification = 43% @ HER full current• Diamond: δmagnification = 3% @ HER full current

Diamond mirror temperature
distribution due to 400W of SR
power

Diamond mirror surface
distortion due to 400W of SR
power

Mirror surface distortion due to200W of SR power at center ofBe mirror

Mirror surface distortion due to400W of SR power at center of
Au+Dia mirror

ANSYS simulations:
M. Arinaga

XRM: LER X-ray beamline(Fuji D8)

Magnetpassage

Opticsbox

X-raybeamline

DetectorBox

XRM: HER X-ray monitor beamline(Oho D4)

Detector
Box

X-ray
beamline

Opticsbox

MagnetpassageXRM:
Digitizer
STURM2ASIC
STURM ASIC for high-speed
readout (G. Varner).
Ver. 1 tested at KEK PF, March
2009.
Ver. 2 fabricated.
Ver. 2 specs:
8 channels/STURM sampling
1 monitor channel
4 TSA sample buffers
8 samples/TSA buffer (32x channel)
288 Wilkinson conversion cells
1-200 GSa/s effective (5ps - 1ns Tstep)
1 word (RAM) sample readout
1+n*0.02 us to read n samples
100 kHz sustained readout (orbit)

XRM: 64-channel system• 64-channel system for testing at ATF2
– Using Fermionics (low-energy) detector.

Preampboard

Digitizer
daughterboard
Digitizer ASIC
(STURM2)

Computer

Detector Array

Motherboard

I/O BoardATF2 x-ray beamline
Duringconstruction

Rotating mask
holder

Detectortable

XRM: SuperKEKB estimated single-shot resolutions(SuperKEKB full current)•Red points: using 64-pixel
detector of same type as at
CesrTA (Fermionics)•Green points: using detector
with improved photon
detection efficiency at higher
x-ray energies (to be
developed)

Detected spectrum(Fermionics detector)

Beam to mask: 12 m
Mask to detector: 36 m

HER

Beam to mask: 8 m
Mask to detector: 32 m

LER

XRM: Detector• Tests with Fermionics detector at Photon Factory showed that
detection efficiency at high energies is very low– Active pixel depth is only 3.5 microns.
• Detector development needed for the future– Higher efficiency at hard x-ray spectrum seen at SuperKEKB– Faster response for being able to directly diagnose head-tailinstabilities at SuperKEKB.
– Trench diode design being pursued:• Deep but narrow pixels• First prototype fabricated at SLAC
• Detector development to continue