Present Status and Future Upgrade of KEK e– Linac

The Present Performanceand Future Upgradeof the KEKB Electron Linac
Kazuro Furukawa, KEK<kazuro.furukawa@kek.jp>

andKEK Electron Linac Group,Linac Commissioning Group

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– Linac

Introduction, KEK e– Linac◆ KEKB Asymmetric Collider Complex andBelle Detector for CP-Violation Study◆ Stable and Robust Operation of Linac
for Higher Experiment Efficiency◆ Many Active Operation Parametersat Microwave Systems, etc.
◆ Frequent Switching between
KEKB e– 8 GeV 1.28 nC Single Bunch
KEKB e+ 3.5 GeV 0.64 nC Single/Dual Bunch(Primary e– 10 nC)
PF e–
PFAR e–2.5 GeV 0.2 nC Multibunch
2.5/3.0 GeV 0.2 nC Multibunch

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– Linac

Regular Operation Statistics◆ Basic Operation Performance
RingCharge[nC]

Energy[GeV]

Injection[/day]

Inj. Time[min.]

8.0~14/18~1.5

KEKB e–1.28
KEKB e+(1) 0.64 x 1
KEKB e+(2) 0.64 x 2

3.5~14~8(single bunch)

3.5~18~4(double bunch)

PF e–0.22.5

1~5PFAR e–0.2

2.5/3.0

12~4800

Machine Down Time700600◆ Operation Hours

500

FY1999FY2000FY2001

Beam Operation Time7297
72037239
Machine Down Time768 (10.5%) 601 (8.3%) 385 (5.3%)
Beam Loss Time74 (1.0%) 54 (0.8%) 22 (0.3%)

400
300
200
100
0rf-trip
FY1999FY2000FY2001

Machine Down: Machine was not ready. (including rf-trip, 10-minute maintenance, etc)
Beam Loss:
Machine was not ready when an injection was requested.

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– LinacBeam Quality Control◆ rf System Optimization[Routine Monitoring of Beam/Machine Parameters]

80000
Failures
Rf trips

70000
60000

◆ Emittance and Matching Condition

50000
40000
30000
20000
10000
0

FY1999FY2000FY2001◆ rf Phasing

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– Linac

Advanced Injection for KEKB (1)◆ Double Bunch Injection
Positron Double Bunch
in one rf Pulse◆ Doubled the Injection Rate
Luminosity Increase ~8%(Bunch Pattern Restriction)

Already 4-week Experience

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– Linac

Advanced Injection for KEKB (2)◆ ContinuousInjection
DuringExperiment- Detector Veto- Beam Pipe Heating- Switch to PFARLuminosity
Increase ~20%

◆ Both “Double-Bunch Injection” and “Continuous Injection”
in the upcoming Autumn Operation
K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

Linac / Ring Upgrade for SuperKEKB◆ for Precise Measurement of B-meson System Parametersand Search for New Physics (ex. SUSY)
SuperKEKB : Luminosity of 1035 cm-2 s-1
with Major Upgrade of Linac and Ring
◆ Luminosity Increase(1) Squeezing Beta at Interaction Region (by factor of 3.3)
(2) Increasing e– and e+ Beam Current (by factor of 3.3)
(3) Exchanging Energies of e– and e+ (to cure e– cloud issues)◆ for Linac(3) is the Major Challenge, as well as (2)Two Schemes are Considered(a) Higher Gradient with C-band Structures(b) Recirculation of Positron
K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

Linac Energy Upgrade with C-Band◆ e+ 8.0 GeV with Doubling the Acceleration Gradient
C-Band Structures : 21 –> 42 MeV/m, 320MeV/unit, 24 Units◆ Lower Emittance with e+ Damping Ring
(1) for Smaller Aperture of the C-Band Structures(2) for Design of the Interaction Region at the Ring
◆ Overview of the Scheme (Green Part is New/Upgrade)

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

C-Band (5712MHz) Components R & D◆ Being Designed for KEKB Linac, Based on the Development by JLC C-Band Group◆ C-Band Klystron: 50MW from Toshiba◆ Pulse Modulator: Compact Type, First Version under Production◆ Driver Klystron: Modified 40kW, Designing◆ Pulse Compressor: TE038 LIPS Type, Designing◆ Acceleration Structure: 2π/3-mode, under Fabrication◆ rf Components: Designing◆
High-Power/Acceleration Test at Spring 2003

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

Linac Energy Upgrade with Recirculation (Backup)◆ No Major Change in Acceleration Components
Damping Ring to Keep Positron for the Next Pulse◆ Slightly Complicated Operation Scheme
Return Line, Bypass Lines at Arc and Target
Multi-Bunch Acceleration with Very Different Characteristics
Before/After the Target◆ Overview of the Scheme

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— LinacLinac Beam-Current Enhancement◆ e– Beam Charge:
3 mA /s —> 15 mA /s (Injection Rate)
1 nC /pulse —> 5 nC /pulse (3.5 GeV)
Already Achieved for Primary Beam for e+ Generation
Emittance Control May be Necessary◆ e+ Beam Charge:
1.5 mA /s —> 3 mA /s (Injection Rate)
0.6 nC /pulse —> 1.2 nC /pulse (8.0 GeV)
Flux Concentrator for Energy Acceptance (Planning)
Double Bunch Acceleration and Damping Ring (?)◆ Continuous Injection
Already Achieved◆ Simultaneous e– and e+ and Injection
Transport Line Lengths, Injection Timing (?)
K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

Linac Beam Measurement and Quality Control◆ Beam Measurement
Between Injections —> During Continuous Injection◆ Stealth Bunch Measurement Possibility
Between Injection Bunches
Fast Kicker, To Prevent Dirty Beam Injection
Fast Actuator Installation
ex. Fast Phase Shifter is under Development
Synchronous Data Acquisition Improvement
Timing System Modification◆ Fast (50Hz) Data Acquisition
Under Development for BPM with Fast Digitizer
Need to Measure Dual Bunch Simultaneously◆ Need More Beam Quality Control

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— LinacConclusions◆ Linac Operates Well with Low Down Rate
Contributes to KEKB/Belle Achievement◆ Beam/Machine Quality Control, Dual-Bunch Injection,
Continuous Injection are Improving
Enhance Integrated Luminosity◆ Linac Upgrade Design for SuperKEKB
Energy Exchange (8-GeV e+) is the Major ChallengeWith C-Band Technology at First
R & D Started This Year, and First Test at Spring 2003
◆ Miscellaneous Improvements are Planned
Considering for SuperKEKB
K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e— Linac

Layout of KEKB Linac◆ 600m Linac with 59 S-band rf Stations,56 of them have SLED with Gain of 160MeV◆ Double (114MHz, 571MHz) Sub-Harmonic Buncher
to Achieve 10ps Pulse Width and 10nC
Sector B

Sector A

A-Gun
Positron Source

180-deg.
Arc

Sector C

C-Gun

Sector 2

Sector 1

PFECS
Sector 3

Sector 4

Sector 5

Beam
Switchyard

KEKB

K.Furukawa, Linac2002, Aug.2002.

Present Status and Future Upgrade of KEK e– Linac

Design Beam and Achieved Performance(1) Gun(2) Buncher(3) Arc(4) e+ target(5) e+ Solenoid exit
(6) Linac endEnergy
Intensity
Pulse width
EnergyEnergy spread (σ)
Intensity
Efficiency
Emittance γβε (σ)
Bunch width
EnergyEnergy spread (σ)
Jitters (p-p)
Drift (with feedback)Emittance γβε (σ)
Transmission
EnergyIntensity
Transmission
Intensity
Specific yield
EnergyEnergy spread (σ)
Intensity
Specific yield
Transmission
Emittance γβε (σ)
Pulse repetition

keV
nC/pulsens
MeV
MeV
nC/pulsemm
ps
GeV
MeV

8-GeV electron
Goal Achieved
200
200
1.5
22
1.8
1616
1.4
0.065
1.5
0.6%

mm

1.995%
0.046
1.7
0.29%
0.17100%

GeVnC/pulse
nC/pulse
e+/e-GeV
GeVMeVnC/pulse
e+/e-GeVmmpps

8
0.15%
1.28

>8
0.05%
>1.28

0.25
50>80%
0.31
50

3.5-GeV positron
Goal Achieved
200
200
13142
2.8
1515
22>10
1190%
0.06
0.08
16
10
1.5
1.7
0.6%
0.38%
0.1%
<0.2%/h
1.7
>95%
100%
3.7
3.7
>10
10
96%
2.4
6.8%
3.5
>3.5
0.125%
0.15%
>0.64
0.82
2.3%
1.5
50

1.4
50

K.Furukawa, Linac2002, Aug.2002.