Timing System at KEK 8-GeV Linac

Timing System at KEK 8-GeV Linac
Kazuro Furukawa, Tsuyoshi Suwada,
Norihiko Kamikubota, Masanori Satoh
Electron/Positron Linac at KEK<URL:http://www-linac.kek.jp/>

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

The timing system of the KEK electron linac has been
restructured for the KEKB project since a higher precision wasrequired compared with the previous project. It provides precise
timing signals for accelerator equipement such as guns, rfsources, beam instrumentation, etc. along the 600-m linac. Thesignals can be synchronized to one of three rings, KEKB, PF andPF-AR. The clock system consists of five synchronizedfrequencies to drive different rf systems. The main clock of thetiming system is 571.2MHz, which is distributed through a
coaxial cable overwrapped with timing pulses. The delayed
signals for over 100 devices are generated at 15 timing stations
along the linac. Gate pulses are also distributed to enableintermittent measurement, etc. Timing signals are controlled
through VME and CAMAC with the linac standard control
architecture. The delay step of the timing signals is 1.75 ns andthe precision is better than 5 ps depending on the location. It
enabled stable long-term operation of the linac and also therecent "two bunch in a pulse" operation with its precise controls.
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Introduction
u Experiment Efficiency for B-Factory
KEKB Electron Positron Asymmetric Collider＝⇒ Stable Operation of Linac
Further Improvementwith 2-bunch and Continuous Injection

u Timing System
High Precision Injection Timing (<30ps,SingleBunch)
Timing Controls for SLED and 2-bunch Inj.
More than 100 Timing Devices along 600m

u Frequent Beam Mode Switch (˜50 Times a Day)KEKB e–KEKB e+,PF e–

8 GeV 1.2nC Single Bunch
3.5 GeV 0.64nC Single Bunch(Primary e– 10nC)
2.5 GeV 0.3nC Multibunch

PF-AR e–2.5/3.0 GeV 0.3nC Multibunchwith/without 2 Bunch Injection

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Peak Luminosity

10.57 /nb/s

579/pb/day

3.31 /fb/7 days
11.41 /fb/30 days
LERHER

140.7 /fb

KEKB

u KEKB Performance
Good Competition

PEP-IIwith PEP-II

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Timing System of Injector Linacu Timing Delivery foru Beam from Electron Gunu Pulsed Microwave Generation, Envelope, SLED Energy Doubler
u Timing for Beam Instrumentationu Injection Timing, Kicker/Septum Trigger
u Components Provide
u Generation of Base Clocks
u Distribution of Timing Signal
u Generation of Hundreds of Delayed Signals
at 15 Timing Stations
u with Good Collaboration between Several Equipment Groups

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Generation of Base Clocks
u (300ps Jitter was Allowed in Previous Project TRISTAN
Asynchronous rf between Linac and Ring)u In KEKB, Single Bunch Beam with Jitter <30ps Required⇒ Need Integer Relation between rf Frequencies
SHB 1
Commonx 11114.24 MHz

10.385 MHz

x5

SHB 2
571.2 MHzKEKB Ring rf

x 49

508.89 MHz

Linac Mainx52856 MHzRing Revolution

÷ 512099.39 kHzu All rf and Timings should be Based on
Common Fundamental Frequency 10.385 MHz
u Freq. Multiplier/Divider was Developed for these rfs
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Beam Timingu Beam Timing is Synchronized to BothPower Line Frequency (50Hz)（for Noise Elimination）
Revolution Frequency of Each Ring（with Bucket Selection）
u For Bucket Selection in KEKB Injection
Synchronizing Also to Common Freq. (10.39MHz)（With Maximum Delay of 0.5ms for 5120 Buckets）
u Can Reduce to 1/N RateLine Locked50Hz

Ring Revolution

1/N

Synchronizer

Bucket Selection

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Simplified Timing Chart
Line-Locked 50Hz
Bucket Selection

0 ~ 500 m s2856MHz
571.20MHz
114.24MHz
508.88MHz
Gun Grid Pulser
Master Trigger
Ring Kicker/Septum
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Distribution of Timing and Clocku Required High-precision Timing at each Equipment
Different Requirement depending on Equipment
Precision <10ps, 1ns, 10ns; Step 〜1ns
u Distribute Clock (571.2MHz) for Delay Countersu Over the Same Cable with High Band-width
u 15 Timing Stations
Mono-Pulse Beam Timing

Overwrap with Clock (571.2MHz)

u Re-Generate Timing and Clock at each Station
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Simplified Block Diagram
Trigger Transmitter

Main RF Station

Phase AGC
Variable
Shifter
Attenuator
Amp508.888MHz

10.385MHz
Fundamental
RFx7x7x11x75

114.24MHz

to Sector Station 1 5x5
571.2MHzto SHB1 to SHB2

to Sector Station ABC

RFCombiner

RFCombiner

PLL
Variable
Phase Shifter

to Linacto Ring

SectorStationGrid Pulser(KEKB)A

Main Station
114.24MHz

1/h Harmonic Number (h=5120)
frev(2.03kHz)
Line-Locked
50Hz
1/N

10.385MHz
Delay

114.24MHz
Delay

Master Trigger

Monocycle
Pulser

SectorStation1571.2MHz(KEKB)

571.2MHz
TD-4 Delay

Synchronizer(PF-AR or PF)
DoubleSynchronizer

Sub-control
StationRing Kicker(KEKB)

ASelector
Grid Pulser(PF-AR or PF)
Ring Kicker(PF-AR or PF)

Sub-control
Station1frev(0.8MHz/PF-AR)or frev(1.6MHz/PF)
114.24MHz

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Timing Stationu Main Station and 15 Sub-Stations
u Main Station Generates Base Signals and Distributes themu Sub-Stations Generate Delayed Timings
u TimingDelay4 (TD4) ECL 16bit Counter Delay (Max 114ms)
u Sub-Stations

StationBeam Station Primary
Sub-Station

Secondary
Sub-Station

NumberReceiver
DelayField BusEquipment

1TD4R
TD4R
RS232CBeam Gun

5TD4V
VME
Modulator

9Trigger Receiver
TD4CAMAC
Low-level rf
Beam Monitor

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Timing Transmission and Re-generation

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Pulsed Microwave Timingu Low-level Microwave Timing
Pulse Envelope, SLED (rf Compressor) Phase Flip
57 ms Delayed Pulse for Stand-by rf Units
8 Sub-stations, 32 Timing Signals (˜1ns stability)u High-power Klystron Modulator Timing
High-voltage Pulse Timing
６Sub-stations, 59 Timing Signals
3 μs

1 μs
Low-level Microwave
53 μs

SLED Flip

High-Power Modulator in Accel. Mode

High-Power Modulator in Stand-by Mode

Beam Timing

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Timing for Beam Instrumentationsu Streak Camera
Precision Much Better than 10ps
4 Locations
u Beam Position Monitors
Precision Better than 1ns (Software Finds Real Peak Locations)
19 Locations, 90 BPM'su Beam Wire Scanners
Precision Better than 1ns２Locations, 14 Scanners
u Source and Beam-Induced Microwave Monitors
Precision Better than 1ns８Locations, 30 Monitor Stations
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Control System
Touch Panel Interface

X-Window Interface for Operation

EPICS Gateway to KEKB-Ring

MS-Windows Interface

Central Network (FDDI, Ethernet)
Device Manager

Main Computer Systems (Unix)

Timing Server Software

Equipment Level Network (Optical Ethernet)

VMEs (~30)

PLCs (~150)

CAMACs (~15)

VXIs (~30)

PC / GPIB / RS232C

Beam Monitor
Timingetc.

RFMagnet
VacuumTimingRF Monitor

GunBeam Monitor
othersu Red and Blue Boxes are Timing System Related
Multi-layer Software Hides Hardware Differences
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

u General Operation Tools
can be Used with Timings
u Active Correlation Plot enables
Automated Parameter
Optimization
Passive Correlation Plots arealso Used to Find
Multi-Parameter Correlationsu Equipment Parameter
Save-Load Panel
Has Many Optional Features
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Past Troubles
u Ethernet-CAMAC Driver Software (Hytec ECC)
Did not work well under Multi-server Multi-client Env.
Much Work-around Software was Writtenu Very Low-rate Output Failure with TD4/TD4V
Comparator Chips for Input Discrim. and Output Width
Stop Output Signals for just 200ms
Rate was less than Once in 2 weeks
All Comparators were Replaced

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Bunch Energy Difference in 2-bunch Modeu Controls of Energy Difference with rf/SLED Timings
Energy Difference is Dependent on Bunch Current(Primary e- 10nC、Secondary e+ 1nC)

u Simple Stabilization Loop

Read Beam Position (x and dx)
at Reference Points

BeamFluctuation

BPM

1BPM

BeamKlystron Klystron

Second bunch

0.99––> Convert into Timings
for Energy Doublers

0.98

Beam Positionsof 2-Bunches

0.97First bunch

BPMs

96.29 ns– Beam Fluctuation––> Convert into Energy
Difference

0.96

Average (Integration)
0.95-100-50

0Gun/SLED Timing [ns]50100x Gain – Offset

Energy Difference Feedback
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV Linac

Jitter Evaluation
Turn Around ThroughSector-5 ~400m x 2<4ps rms

Single TD4<3ps rms

K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV LinacConclusion and Future
u Timing System Works as Expected
Achieved Satisfactory Precision
Flexible Controls of >100 Delays
u Performance of Timing System
Based on Beam Width Meas.
Far Better than 10ps (˜3ps)
u Surveillance System
Clock Phase Monitor Oscilloscope
TD4 Monitor with TDC
u Improvement of Beam Operation
50Hz Instrumentations
for Fast Beam Feedback etc.

Intermittent Beam Monitoring
Even During Continuous Injection
K. Furukawa, KEK, Icalepcs2003, Oct.2003.

Timing System at KEK 8-GeV LinacThank you ...

K. Furukawa, KEK, Icalepcs2003, Oct.2003.