Timing System Upgrade for Top-up Injection both to PF and KEKB
Kazuro Furukawa, Tsuyoshi Suwada, Masanori Satoh, Eiichi Kadokura
High Energy Accelerator Research Organization (KEK)KEK 8-GeV Linac provides electrons and positrons to Photon
Factory (PF) and B-Factory (KEKB). Because of the nature ofthose factory machines, both quantity and quality of the beams arerequired. In order to improve the injections, quasi top-up injectionsof electrons to PF and KEKB rings have been planned and a newbeam transport line was built. Fast beam switching mechanisms
are being developed and installed. The timing and control system
is also reinforced to realize fast (50Hz) switching of rf timing pulses,

Timing / Event Distribution System

low-level rf, beam instrumentation parameters, and beam feedback
parameters. The present timing system provides precise (jittersdown to 3ps) timing pulses to 150 devices. Many of the signals will
be upgraded to enable the fast switching scheme with an event
system. At the same time a double-fold synchronization between
asynchronous Linac and PF rf signals was developed to achieveprecise injection timing mainly because both rings haveindependent circumference correction systems.

rf Synchronization System

Present Hybrid System

LLRF

Synchronization between Linac and KEKB
LLRF

Central Timing Station
50 Hz

571.2 MHz

OverlaidTimingSignal

Four
EventLines

rf Frequencies are derived based on Integer Relations. They arecontinuously adjusted to compensate the KEKB Ring Circumference.

Sub-Timing Stations at 15 Locations

Beam Timing

Sub-Systems, rf, Beam Instrumentations, etc~150 Timing Signals with Jitter of ~3ps are provided.
Each Station consists of Many VME or CAMAC modules.

New System with Event Generator and Receivers
LLRF
Event Generator at Central Timing Station
571.2 MHzand
Event / 50 Hz

Single Fiberforeach Station

Event Receivers at Sub-Timing Stations
Sub-Systems, rf, Beam Instrumentations, etc~180 Timing Signals with Jitter of ~3ps will be provided.
Event Generator and Receivers (EVG/EVR200 from MRF)
simplify the system, and they enable the fast switching oftiming, digital and analog parameters.

New Synchronization between Linac and PF Ring
Linac SHB 1

Event System Configuration

114.24 MHz

GunARC

50/N HzEvent Receivers
SB_3

SB_4

SB_5

e– BT (PF)PF Revolutione+ BT (KEKB)

1.6 MHz

Flip-flopFlip-flop
Precise-delay

Gun

Flip-flope+ Target

114.24 MHz is already defined by the KEKB ring Circumference asdescribed above. However, 1.6 MHz (PF Ring Revolution Frequency) is
also continuously adjusted to compensate the PF Ring Circumference atthe same time.

e– BT (KEKB, PFAR)

Event Generator
Cont-3Cont-4Cont-5CentralAn Event Generator and 6 Event Receivers are installed at
first in Sectors Number 3, 4 and 5, where fast switching ofmany accelerator parameters are required to enable thefast Beam Switch.

Parameter / Timing Switching (up to 50 Hz)! Pulsed Bending Magnet! Fast BPM read-out System! Streak Cameras! Wire Scanners! Low-Level rf Parameters! rf Measurement Parameters! rf Active / Stand-by! Beam Feedback Systems! Parameter Manipulation / Display! Archiving! etc.
(P resent S yst em needs switc hing t im e up to 30
seconds, and will gradually be upgraded to 50 Hz.)

This circuit provides the Synchronization between those asynchronous
signals with Jitter down to 300ps.

Beam Pulse Selection
Mostly KEKB

25Hz Allocated

10Hz Allocated

KEKB
50 Hz
50-1 Hz50-2 Hz50-4 Hz50-5 Hz···KEKB50/2 Hz
50/4 Hz50/6 Hz50/8 Hz50/10 Hz···

KEKB
50/5 Hz50/10 Hz50/20 Hz50/25 Hz50/50 Hz···

PF-Ring
0 Hz
1 Hz
2 Hz
4 Hz
5 Hz
···

PF-Ring
50/2 Hz50/4 Hz50/6 Hz50/8 Hz50/10 Hz···

PF-Ring
50/5 Hz50/10 Hz50/20 Hz50/25 Hz50/50 Hz···

Because of the constant-interval requirement to Septum/Kicker Power
Supplies at the moment, Beam Pulse Selection is Restricted. Currently
Above three Schemes are planned. After the Power Supplies are Tuned,unrestricted Beam Pulse Selection will be enabled.