K.Furukawa, KEK, Nov.2015. Injector Linac Progress towards SuperKEKB Progress of Injector Linac...

K.Furukawa, KEK, Nov.2015.Injector Linac Progress towards SuperKEKB

Progress of Injector Linac

Kazuro Furukawafor Injector Linac

1


40-times higher LuminosityTwice larger storage beam Higher beam

current at Linac20-times higher collision rate with nano-beam scheme

　 Low-emittance even at first turn Low-emittance beam from

Linac Shorter storage lifetime Higher Linac beam current

Linac challengesLow emittance e-with high-charge RF-gun

Low emittance e+with damping ring

Higher e+ beam currentwith new capture section

Emittance preservationwith precise beam control

4+1 ring simultaneous injection

Mission of electron/positron Injector in SuperKEKB

2

Linac Upgrade Overview


Required beam parameters

Stage KEKB Phase-I SuperKEKB

Item e+ e- e+ e- e+ e-

Energy 3.5 GeV 8.0 GeV 4.0 GeV 7.0 GeV 4.0 GeV 7.0 GeV

Bunch charge

Primary e-10nC

→ 1 nC

1 nC

Primary e- 4nC

→ 0.2 nC1 nC

Primary e-10nC

→ 4 nC

5 nC

Norm.Emittance (ge)(mrad)

2100 100 2400 150100/20

(Hor./Ver.)50/20

(Hor./Ver.)

Energy spread 0.125% 0.125% ±0.5% ±0.5% 0.1% 0.1%

Num. of Bunch / Pulse

2 2 2 2 2 2

Repetition rate 50 Hz 50 Hz 50 Hz

Simultaneous top-up injection

3 rings (KEKB e-/e+, PF)

No top-up4 rings

(SuperKEKB e-/e+, PF, PF-AR)

3


Linac Schedule Overview

4

RF-Gun e- beamcommissioningat A,B-sector

e- commiss.at A,B,J,C,1

e+ commiss.at 1,2 sector (FC, DCS, Qe- 50%)e- commiss.at 1,2,3,4,5 sector

non damped e+ commiss.at 1,2, 3,4,5 sectorse- commiss. at A→5 sectors

damped e+ commiss.at 1→5 Qe+ = 1~4nCe- commiss.at A→5 Qe- = 1~5nC

: Electron

: Positron

: Low current electron

2 nCPhase2

1 nCPhase1

Location↓

Time →

Phase1: high emittance beam for vacuum scrubPhase2,3: low emittance beam for collision

Schedule

Without Top-up

4 nCPhase3

Improved RF gun

Direct PF-AR BT

DR Commiss.

Step-by-stepLicenses

Low Emittance

Beams

4+1 RingInjections


JFY2010

Dismantle KEKB

KEKB operatio

n

SuperKEKB upgrade construction

SuperKEKB operation

Startup, conditionin

g, etc.

SuperKEKB master schedule

Belle II install,QCS install

Phase 1 Phase 2 、 3

・・・・・・

DR

Phase 1 commissioning ： Basic machine tuning Low emittance beam tuning Vacuum scrabbing

Phase 2 commissioning ： Squeezing beta at IP Beam collision tuning Start physics data taking

Phase 3 ： Physics run with full Belle II with VXD

DR commissioning starts prior to Phase 2

JFY2011 JFY2012 JFY2013 JFY2014 JFY2015 JFY2016 JFY2017

Now (Nov, 2015)

About 10 years

Akai, Jun.2015.

5


Subjects to Consider

Too many subjects !

Phronesis needed (Greek: Practical wisdom, Ability to understand the Universal Truth)

6


Linac Upgrade Progress towards SuperKEKB (1)

High-charge low-emittance RF gun developmentQTWSC cavity and Ir5Ce

photo cathode developments

Positron generator commissioningGood agreement with

the simulation results

Precise alignment for emittance preservationRecovering after earthquakeReaching specification of 0.3mm

Utility upgrade during FY2014 for electricity (+1.5MW) and cooling water (+1400L/min)

7

Signal from primary electron

Signal from positron with opposite polarity

Ir5CeCathode

Quasi traveling wave side couple cavity

Positron generator



Linac Upgrade Progress towards SuperKEKB (2)

High power modulator upgrades Low-level RF controls/monitor

Pulse-to-pulse modulation (PPM) between 4+1 ringsMore spaces for increased number of devices

Beam instrumentationLarge/small aperture beam position monitors (BPM)Precise/fast and synchronized BPM readout systemWire scanners and beam loss monitorsStreak cameras (Deflectors, etc)

Event timing control systemCombination of MRF & SINAP modulesEssential for PPM operationPrecise timing & synchronized controlsBucket selection at DR and MR

8

SINAP event modules


Beam wire scanner


Recent Works

9

Recent works

Thermionic gunfor high-current beam

RF gunfor low-emittance

beam

Thermionic gunat #A1 region

Positron generatorat #15 region Iron shield

Positron generator complex


Preparation of Thermionic Gun Refurbished

Raise by 75cm not to conflict with straight RF-gun As well as angled RF-gun

~ Jun.2015. May serve

electrons in phase-Iprimary electron for positron generation in phase-II and later

10

Thermionic gun

RF gun

Thermionic Gun


Positron generation for SuperKEKB

New positron capture section after target with Flux concentrator (FC) and large-aperture S-band structure (LAS)Satellite bunch (beam loss) elimination with velocity bunchingPinhole (2mm) for passing electrons beside target (3.5mm)Recently, facing discharge difficulties at maximum field

Flux Concentrator

e+

5 nC injection e-

10 nCprimary e-

bridge coils

target

beamhole

pulsed ST

DC QM

pulsed QM

side view

spoiler

solenoid

LAS Accel. structure

11

positronproductionTarget

Flux Concentrator

BridgeCoils

primary e- beam

e+ beam

11

Positron Enhancement


Radiation protection licensesStep-by-step upgrade of beam limits

Final goal is 1250/625 nA before/after targetSame as KEKB

ApplicationsFall.2013. 10 nA at #28 dump, 1250 nA at #A2 dump

Spring 2014. New utility rooms, 50 nA at #61 straight dump

Jun.2015. 200 nA at #15 target

Early 2016.(?) 800 nA at #15 target, 625 nA at #61

Sometime 2016.(?) 1250 nA at #15 target

Shield, shield, shield, shield …

12

Schedule


Summary Steady progress towards first MR injection in FY2015

Finished earthquake disaster recovery in 2014

Will make step-by-step improvements up to Phase-III

Alignment: almost confident on the required precision (0.1-mm local, 0.3-mm global), need to maintain for longer term

Positron generator: another license test, need discharge analysis

Thermionic gun: re-commissioned, working

RF gun: following recommendations at review meetings

Need much more radiation shield

Will balance between final beam quality and progressive operation

Will select optimized route depending on available resources

With some Phronesis we may enjoy coming beam commissioning

13

Summary


SuperKEKB dual rings

Mt. Tsukuba

600m InjectorLinac

PF-AR

PF

14

Thank you

K.Furukawa, KEK, Nov.2015.Injector Linac Progress towards SuperKEKB 15

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K.Furukawa, KEK, Nov.2015. Injector Linac Progress towards SuperKEKB Progress of Injector Linac...

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