K.Furukawa, KEK, RF-gun review, Feb.2015. Linac Upgrade towards SuperKEKB Injector Linac Kazuro...

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Transcript of K.Furukawa, KEK, RF-gun review, Feb.2015. Linac Upgrade towards SuperKEKB Injector Linac Kazuro...

Linac progress

Injector LinacKazuro Furukawafor Injector Linac1K.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKB1Thanks to the reviewersDr. Tsumoru Shintake, OIST, chairDr. Matt Poelker, JLABDr. Sasha Gilevich, SLACDr. Yosuke Honda, cERL/KEK2K.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKB2

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 currentLinac challengesLow emittance e-with high-charge RF-gunLow emittance e+with damping ringHigher e+ beam currentwith new capture sectionEmittance preservationwith precise beam control4+1 ring simultaneous injectionMission of electron/positron Injector in SuperKEKB3Linac OverviewK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBHigher Injection Beam CurrentTo Meet the larger stored beam current and shorter beam lifetime in the ring4~8-times larger bunch current for electron and positronReconstruction of positron generator, etcLower-emittance Injection Beam To meet nano-beam scheme in the ringPositron with a damping ringElectron with a photo-cathode RF gunEmittance preservation by alignment and beam instrumentationQuasi-simultaneous injections into 4 storage ringsSuperKEKB e/e+ rings, and light sources of PF and PF-ARImprovements to beam instrumentation, low-level RF, controls, timing, etc

3Linac Upgrade for SuperKEKBLow emittance RF-gun developmentPhoto-cathode: stability, long-lifetime, quantum efficiencyLaB6, Ir5Ce and other possibilities, 5nC/bunch achievedLaser : high-power, stability, bunch profile managementNd:YAG media, LD excitation, 1.5mJ / 30ps achievedFiber laser development for profile controlCavity : field optimization Disk and washer (DAW) cavityQuasi traveling-wave (QTWSC) cavityOperation : higher stability and reliabilityPF injection was tested, longer-term tests, backups, are planned

4BunchCompressionABC12345HER7.0 GeV 5nC x 220 um LER4.0 GeV e+4nC x 2Primary e for e+3.2 GeV, 10nC x 21.1 GeV e+ damping ringEnergy CompressionBunch CompressionPF2.5 GeV0.1nC x 1New RF-gun5 nC for e, 10nC for e+IrCe cathode, Fiber laser, DAW cavityNew e+ Capture with FC PF-AR6.5 GeV5nCJ-arc1.5 GeVEnergyCompressionSY2SY3

Ir5Ce

DAWK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBLinac Upgrade Progress towards SuperKEKBHigh-charge low-emittance RF gun developmentQTWSC cavity and Ir5Ce photo cathode works well

Positron generation confirmation for the first timeGood agreement with the simulation results

Precise alignment for emittance preservationRecovering after earthquakeReaching specification of 0.2mm

Utility upgrade during summer 2014for electricity (+1.5MW) and cooling water (+1400L/min)5

Signal from primary electronSignal from positron with opposite polarity

Ir5CeCathode

Quasi traveling wave side couple cavity

Positron generator

K.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKB

Linac Schedule Overview6RF-Gun e- beamcommissioningat A,B-sectore- commiss.at A,B,J,C,1e+ commiss.at 1,2 sector (FC, DCS, Qe- 50%)e- commiss.at 1,2,3,4,5 sectornon damped e+ commiss.at 1,2, 3,4,5 sectorse- commiss. at A5 sectorsdamped e+ commiss.at 15 Qe+ = 1~4nCe- commiss.at A5 Qe- = 1~5nC: Electron: Positron: Low current electron2 nCPhase21 nCPhase1LocationTime Phase1: high emittance beam for vacuum scrubPhase2,3: low emittance beam for collisionScheduleK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBAlignmentHigh-precision alignment was not necessary in PF and KEKB injections, and it was much damaged by earthquake in 2011.Instead of flexible-structure girder before earthquake, rigid-structure was adopted with jack-volts and fixed supports.Reflector pedestals are developed and mounted onto quad magnets and accelerating cavities for laser-tracker measurement.Iterative measurement and adjustment with 500-m straight laser and position sensors should enable 0.3-mm global alignment.Laser tracker should enable 0.1-mm measurement within 10-m girder unit.Displacement gauges, hydrostatic leveling, inclinometer are also employed.Remote measurement system and girder mover system will be necessary for longer term, and are under development.7AlignmentK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBAlignment progress in 2014For the first time at 3-5 sectorsHorizontal axis: sensor number from sector C, 1-4, to sector 5 (~80 m/sector)Vertical axis: voltage (~displacement at 0.25~0.5mm/mV)Some girders were not yet upgradedMoved up to 3 mm not to break vaccuum8

AlignmentDisplacement / mVSector CSector 5K.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBAlignment progress in 2014For the first time after earthquake at downstream sectorsSeveral measurements during summerMeasurement reproducibility was confirmed up to ~0.2 mmWhile there existed several conflicting measurements, consistent scheme has been establishedMovement of tunnel by several 10s of micrometer was observed ( mover)Further work necessary in 2015, for alignment and girder replacement9

Higo et al.~5mm~10mmAlignmentK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBPositron Generation4-times more positron is required at SuperKEKB than KEKBSafety measure was taken after cable fire during the test of Flux Concentrator (FC)New components in 100-m capture section were tested in stepsHigh voltage tests in tunnel in AprilBeam tests with electronin May10

Positron EnhancementK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBPositron generation for SuperKEKBNew 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 electrons beside target (3.5mm)Beam spoiler for target protection

Flux Concentratore+5 nC injection e-10 nCprimary e-bridge coilstargetbeamholepulsed STDC QMpulsed QMside viewspoilersolenoidLAS Accel. structure11

positronproductionTargetFlux ConcentratorBridgeCoilsprimary e- beam e+ beam11Positron EnhancementK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBPositron GenerationInstallation of positron generator for SuperKEKB in April 2014(Beamline construction since summer 2013)(positron target, spoiler, Flux Concentrator, bridge coils, LAS structures [x6], DC solenoids [16+13], e+/e- separator, quads [>90])Commissioning of positron beam, observation of the first positron after reconstruction for SuperKEKB, further improvements expected

Oct.~Dec.2014 : Linac commissioningJan.~May.2015 : ConstructionJun. : Linac commissioningJul.~Sep.2015 : ConstructionOct.~Jan.2016 : Linac commissioningT.KamitaniPrimary e- [nC]Positron [nC]EfficiencyParametersJune 20140.60.1220%FC 6.4kA, Solenoids 370A, LAS capture field 10 MV/mSpecification(at SY2)10.05.050%FC 12kA, Solenoids 650A, LAS capture field 14 MV/mDR injection(2017?)4.040%Energy spread acceptance 0.5%x17x42x2.5Positron EnhancementK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBRF-Gun development strategy for SuperKEKBCavity : Strong electric field focusing structureDisk And Washer (DAW)=> 3-2, A-1(test)Quasi Traveling Wave Side Couple=> A-1 => Reduce beam divergence and projected emittance dilution Cathode : Long term stable cathodeMiddle QE (QE=10-410-3 @266nm) Solid material (no thin film) => Metal composite cathode => Started from LaB6 (short life time) => Ir5Ce has very long life time and QE>10-4 @266nmLaser : Stable laser with temporal manipulationLD pumped laser medium => Nd / Yb dopedTemporal manipulation => Yb doped => Minimum energy spreadRF gun for low-emittance electronK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKB

Emittance 5.5 mm-mradSize 0.4 mmEnergy spread 0.6%Bunch shapeGun Exit5 nC

10 nCBeam tracking simulation resultRF gun for low-emittance electronM. YoshidaK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBEnergy spread reduction using temporal manipulation15

GaussianSquare5nC10nC15nC20nC20nC15nC10nC5nC5nC electron15nCPrimary beam for positron productionttEnergy spread of 0.1% is required for SuperKEKB synchrotron injection.RF gun for low-emittance electronM. YoshidaK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKB5.6 nC / bunch was confirmedNext step: 50-Hz beam generation &Radiation control16

Quasi traveling wave side couple cavityCascaded frequency doublersYb fiber and Yb:YAG think disk laserIr5Ce photo cathodePhoto cathode RF gun developmentRF gun for low-emittance electron

Part of multi-pass AmplifierK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBGU_A1 Laser Configuration as of Dec.201417

RF gun for low-emittance electron

K.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBPhoto cathode RF gun improvementCrucial for high-current low-emmittance beamNew Ir5Ce cathode and new cavity QTWSC were successfulBasic features were confirmed at 2 ~ 5 HzExpect beam parameter and stability performance at 50 Hz, with multi-pass amplifiers and cooling systemResolved the issue of oscillator synchronizationStaged laser system improvements with beam measurement system

18RF gun for low-emittance electronK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBR0 ARC Dispersion: need for investigationMeasurement (dot) compared with expected value (line)19

R36R16CommissioningPreliminaryK.Furukawa, KEK, RF-gun review, Feb.2015.Linac Upgrade towards SuperKEKBTowards the injectionWe didnt completed