BPM and bunch feedback systems
Makoto Tobiyama
for SuperKEKB Beam Instrumentation GroupSuperKEKB BxB FBContents

Beam position monitors– Narrowband detector– Gated turn-by-turn monitor– IR position feedback– Damping ringBunch feedback systems– Transverse bunch feedback– Longitudinal bunch feedback

SuperKEKB BxB FBIntroduction
SystemQuantity
HER

LER

DR

Beam position monitor (BPM)

466

444

83

Displacement sensor

110

1080

Transverse bunch feedback system

221

Longitudinal bunch feedback system0(1)10Visible SR size monitor

111X-ray size monitor

110

Beamstrahlung monitor

110

Betatron tune monitor

221

Beam loss monitor

20034DCCT111CT110Bunch current monitor

111

SuperKEKB BxB FB

Configuration of main BPM system
Gated
TbT



Separate HER and LER
BPM systems.
– Cutoff freq. of LER chamberlower than 1GHz (989MHz).



Gated
TbT

Continue to use VXI
system with MXI (1/2)
connection.
Selected 270 BPMs havegated turn-by-turn
monitoring function.
– By Phase 1 : A total of~110 G-TBT will be installed.SuperKEKB BxB FBBeam position monitorsAll button electrodes have been fabricated, and most ofthem (except several special sections) have been
installed in the tunnel.
Cabling work and re-installation of the BPM cables arein progress and are expected to be finished by Sep/2014.
All VXI main frames have been renewed and re-installed.

SuperKEKB BxB FB

Pigtail cable difficulties

Many cables had failed on the insulation resistancecheck, one had shown short-circuit.
– Checked all the BPMs using TDR.

SuperKEKB BxB FBGood (acceptable) TDRSuperKEKB BxB FB

SMA connector not in good contact

SuperKEKB BxB FB

Damaged cableSuperKEKB BxB FBNear SMA connector (or FT?)SuperKEKB BxB FBSoldering fault in connector

SuperKEKB BxB FBMeasureTake great care of handing the cable!
Check all the new pigtail cables using TDR when arrivedKEK.
– Still 6 out of 600 cables had failed recently, though.

Improvement of soldering control for the connectors.
– New insulators to protect invading the unnecessary solder to theconnector.

SuperKEKB BxB FB

509MHz narrowband detector
120 Narrowband(509 MHz) detectors have been arrived.
Ratio S/N’s have been confirmed to be better than90dB.

ratioS/N(B/A)
ratioS/N(C/A)
ratioS/N(D/A)

signal selector

20A_20deg

A/D converter

2520Count

15

10

attenuator& down converter

50
93

93.5

94

94.5

95

95.5

DSP(SHARC)

dB

Ratio S/N of first 20 modules

A 509 MHz narrowband detector

SuperKEKB BxB FB

Gated turn-by-turn monitor
509MHz/1GHz narrow band detector, ormedium-band detector

FPGA(Spartan6)

Pilot bunch signal orinjection beam
BPM
Fast gateswitch

BPF&Amp

Gate width~6ns

508.886MHz & FID

Log
Amp

TBT
Data

14bit
ADC

SuperKEKB BxB FB

117 units will be ready1U size
4ch Noise cancelling fast switch
GbE Ethernet connection

SuperKEKB BxB FB

Noise cancelling fast gate
Fast fall/rise <0.6ns

Single SW noise

50mV/div

noise cancel

2mV/div

SuperKEKB BxB FBGood isolation(>80dB)
RF to narrow
IL -2.8dB(0.5G)-4.4dB (1G)

RF to narrow
Leak -74dB(0.5G)-79dB(1G)

RF to TbT
ISO -96dB(0.5G)-88dB(1G)

RF to TbTIL -4dB(0.5G)

SuperKEKB BxB FB

Position error
5020,000
MeanLinear Fit
ADC Count

3010,00020Std. Deviation

5,000
010-80-60-40
Input(dBm)-200Standard Deviation40

15,0000Standard deviation of ADC from -50dBm to -10dBm
corresponds roughly 30um of position jitter.

SuperKEKB BxB FBFPGA FW and EPICS device support
FPGA(Spartan6 XC6LX100T-3FGG484)– Gate timing : 508MHz counter delay+width(with ext. D-FF re-sync) x4ch. Position within ±6ps, Jitter <3.3ps in sigma.
– Data acquisition for 14bit ADC(4ch) (+ADC timing)
External DDR3 memory for longer data storage.
 Simple position calculation.
– Housekeeping measurements (temperatures, voltages, etc.)– Ethernet control
SiTCP for ultra-fast data transfer (400MB/s).
 UART connection for debug use.
 Online firmware update function without JTAG connection.


Direct TCP/IP (and UDP) connection.
– Semi long-term (accelerated) load test.
Fixed several bugs in both FPGA firmware and device support.

SuperKEKB BxB FBFabrication


A total of 117 units will be ready by the start of Phase 1operation.
Fulfillment of other ~150 units depends on the budget.

SuperKEKB BxB FB

IP orbit feedback detector



Tentative specification

509MHz– Resolution <1um– Repetition 5 kHz– Bandwidth ~100 Hz (FB)

17MHz

frev X 990=98MHzSuperKEKB BxB FBSuppression of crosstalk

BPF accommodates ferrite.
Transformers and a balun at input
ports are covered by ferrite cores.

Isolators are shielded by copper sheets.

SuperKEKB BxB FB

Position resolution



R&D of a down-converter has completed. Ready tofabricate (scheduled on FY2015).
Power supply controller (PS I/F) is in design stage and a
prototype will be made in FY2014.

SuperKEKB BxB FB

Damping ring BPM
LR_MAP

15105Y0-5-10-15-15-10-5051015

X
1515
Y=0
Y=2mm
Y=5mm

50-5-10-15-15

X=0
X=-2mm
X=-5mm10
L/R Calculation(mm)

L/R Calculation (mm)1050-5-10-10-505X Position (mm)1015-15-15-10-505Y position (mm)1015

SuperKEKB BxB FBDamping Ring BPM
VME-based L/R detectors have been fabricated andcalibrated.
0Power(dBm)
5th order fit

Power(dBm)-20-4089

Y = M0 + M1*x + ... M8*x + M9*x

-60

-80

-100

0M0-161.33

M1M2

0.077114-3.068e-5

M3
M4

6.892e-9-8.7973e-13

M5

6.4085e-17

M6
M7-2.4795e-21
3.9503e-26

R

0.99989

2000 4000 6000 800010000120001400016000
ADC



Need bunch timing (ADC timing) through Event system.
– 1 (or 2) Hz data acquisition.

SuperKEKB BxB FBSpecial monitors
Orbit interlock– Libera Brilliance+turn-by-turn mode, latency <10 turns
 Evaluation in progress: Latency < 4 turns
Medium-band detector– Libera Brilliance+, FA mode (10kHz)– Tsukuba local chromaticity correction areaSynchrotron oscillation monitor– Re-use 508MHz I/Q detectors.
– Use VME-based ADC, timing.

DCCT– Modified to cope with the increased beam current (LER).
– Faster data acquisition using fast digitizer (SL1000 or Agilent
34410A)SuperKEKB BxB FBSuperKEKB Transverse FB planSuperKEKB BxB FBSuperKEKB Longitudinal FB planInstall LFB in LER only. HER is optional.
Considering to use 4 DAFNE type kickers, with 2-input, 2-output ports
for larger capture range.

SuperKEKB BxB FB

New bunch detection electronics
1U size detection circuit / plane(2xH/2xV for transverse, 1 for longitudinal)

Inside of the transverse
detection circuit.-->Internal timing has already beenadjusted using a SRD pulsar.
Timing difference between twoinputs will be adjusted using atrombone delay inside.

SuperKEKB BxB FB

Bunch feedback systems

Most of the FB-related vacuum components have been
installed.

Remains:– LER-LKicker(Aug/2014)

SuperKEKB BxB FB

DR transverse bunch feedback

Mainly to suppress the bunch oscillation due toinjection/extraction kickers.
Position detectors are the same as SuperKEKB.
iGp8s and AR250A250 amplifiers will be used.

SuperKEKB BxB FBLongitudinal kicker

2-input, 2-output, DAFNE type kicker.
center frequency =2.25 x fRF (1150 MHz)
Bandwidth ~ 250MHz
10 wideband UHF amplifiers (R&K and Millimega) areready (900M-1.8GHz, Po=500W).
NameXXY Plot 6Y

HFSSDesign1

m10.00 1.0800 -2.9186
m2

Curve Info

1.3050 -2.9916

m1dB(S(1,2))
Setup1 : Sw eep

m2-5.00-10.00-15.00dB(S(1,2))

-20.00-25.00-30.00-35.00-40.000.50

Q~ 5, Rsh ~ 1.6kΩ by HFSS calculation

0.75

1.00

1.25
Freq [GHz]

1.50

1.75

2.00

SuperKEKB BxB FB

Schedule

Cabling work
– Tunnel– Control room

: Sep/2014: Jun/2014

Installation of G-TbT
Feedback systems: Oct/2014– Installation of vacuum components : Aug/2014– Cabling in the local control: Oct/2014
Software (EPICS device support and GUI etc.) workneeded before commissioning.
DR schedule strongly depends on the progress of othergroups.

SuperKEKB BxB FBBackup

SuperKEKB BxB FBMean / Sigma
10

3.32
3.3

5
Mean (ps)03.26
Sigma (ps)

3.24
-5
3.22
-100

1000

2000

3000
Delay

4000

3.2
5000

Sigma (ps)Mean (ps)3.28

SuperKEKB BxB FB

4ns Gate

SuperKEKB BxB FB

Switching noiseSuperKEKB BxB FB

Log amplifier output (using AR beam)
6dB wide

6dB Narrow

SuperKEKB BxB FBCextとSigma• 最低使用領域(-80dBm)ではCext(100,18,7,0)で48、89、89、150となる• 常用域（-40dBm)では2、3.2、3.9、5.5となる• 最大域(-15dBm)では2、3.0、3.7、5.2となる

200

Sigma

150
Sigma(0pF)
Sigma(100pF)
Sigma(7pF)
Sigma(18pF)

100

500-100-80-60-40Power(dBm)-200

SuperKEKB BxB FBSuperKEKB
2
1.8
CH1(Wide)
CH2(Narrow)

Log Output(dB)

1.6

最大条件

1.4
1.2
10.8
0.6

INJ
020

4060

Attenauation(dB)

80100

SuperKEKB BxB FB

20dB Amp -4dB loss 100pF
2Cor(Vout)Sim(Vout)

Vout(Log)

1.5Maxbeam
σ2Inj.
σ1010.5-100102030
Att(dB)

40506070

SuperKEKB BxB FBSuperKEKB BxB FB

試験回路

SuperKEKB BxB FB

Q=5.1
NameX

XY Plot 6Y

HFSSDesign1

m10.00 1.0800 -2.9186
m2

Curve Info

1.3050 -2.9916

m1

dB(S(1,2))
Setup1 : Sw eep

m2-5.00-10.00dB(S(1,2))-15.00-20.00-25.00-30.00-35.00-40.00
0.50

0.75

1.00

1.25
Freq [GHz]

1.50

1.75

2.00

SuperKEKB BxB FB

E_z計算0deg
600

Q=5.1
Rsh=1628ohm

RealImag400

Real2000-200-400050100150200250A300350400

SuperKEKB BxB FB

GdfidLモデル

SuperKEKB BxB FB

ポート出力(1pC)

SuperKEKB BxB FBSuperKEKB BxB FB

longitudinal wake

Loss factorは0.4V/pC

SuperKEKB BxB FB

Impedance(real)SuperKEKB BxB FB

Impedance(imag)

SuperKEKB BxB FB

Bunch current monitor

MAX108 8bit ADC
Spartan6 FGPA
VME 2W size

Bunch current information will besent through reflective memory(real-time) to the bucket selection
system during injection period.

SuperKEKB BxB FB

Betatron TuneGlobal tune measurement for multi-bunch, small beam
current
Gated tune measurement for pilot bunch only
PLL excitation of the pilot bunch using iGp12 or Lock-in
amplifiers