RTML( Except Bunch Compressor )

Parameters and LayoutDiagnostics and Beam TuningAccelerator PhysicsAccelerator Components

S.Kuroda ( KEK )

Beam Parameters

Layout

Extraction from the DR ( ERTL/PRTL )

No vertical dogleg in ERTL because of the DR vertical position

Return Line ( ELTL/PLTL )• Following the earth’s curvature in ML tunnel

V correctors in each QV dispersion matching by v correctors at both ends

Return Line ( ELTL/PLTL )(2)• Horizontal dogleg at the junction of ML and

BDS, which is different in ELTL and PLTL due to positron target

Geometry of the dog-leg defined in document EDMS: D*0969955

Return Line ( ELTL/PLTL )(3)Mountain topography

Flat topography

Turn Around

Spin Rotator

H-dogleg

V-dogleg

z

x

z

y

• Horizontal dogleg• Vertical dogleg to adjust

elevation to ML• 180-8 deg. turn around with

dispersion matching( 8 deg. is needed for spin rotator )

• Bunch by bunch feed-forward. Time delay is 600 ns.

Spin Rotator

Diagnostics• Cavity BPM • Laser Wire for emittance measurement

Beam Tuning

• Dispersion Correction– Normal and skew Q in ERTL/PRTL in hx region• In pairs with –I --> No introduction of coupling

– Normal Q in h/v dogleg of Turn Around• Coupling correction– 4 skew Qs in zero dispersion region downstream

of ERTL/PRRTL and Spin Rotator

Beam Physics Issues

• ISR

Vertical emittance growth is negligible • Beam-Ion instability ( L.Wang, et al )– < 2mPa

Horizontal emittance growth

Arc( RTL ) 90nm (1.1 % )

Turn-around 430nm ( 5.4 % )

Beam Physics Issues (2)

• Stray Field– Tolerance ( K.Kubo ) • 2nT for orbit jitter of 0.2sy

– This can be corrected by fast feed-forward

• Higher for emittance growth

Stray Field ( Measurement )

N.Solyak 2011

Beam Physics Issues (3)

• Halo Formation from Scattering( S.M.Seletskiy )– 2mPa 2e-6 of beam intensity < tolerance of 1e-5

• Space-Charge Effect– Incoherent space charge tune shift is O(0.15) in v– To be studied

Beam Physics Issues (4)

• Emittance Preservation ( A. Latina )

Accelerator Components• Magnets

• Vacuum– Requirement: < 2mPa

Summary and Work to Be Done

• Lattice and optics design is almost done in TDR– Must be re-designed when the accelerator length is

adjusted. • A few things of accelerator physics issue to be

done?– Simulation study should be continued( emittance, ..)– Stray field measurement should be continued.– Space charge tune shift– …