LINAC4 transfer line – optics

M. Eshraqi, L. Hein, A. Lombardi (BE-ABP)

LINAC4 transfer lines : 177.31 m (from PIMS out to foil); 69.83 m new line,then join at BHZ20 the present Linac2 line (107.48 meters from BHZ20 to foil). Active elements : 4+2bendings;16+18 quads,11+11 steerers and 1 RF cavity.

1. Optics 2. Layout3. Tunability4. Safety margins

L2PSB

L4

↕ 2.5m

Optics-layout. •Uncompensated longitudinal space charge forces, •Dispersion and space charge•X-Y coupling •Bottlenecks : RF cavity; septum , distributor

•Match the six conditions at the PB (disp=0;dis-1.4;various beta)•Contain the emittance increase (30% at max, can be reduced)•Accept energy swing of 1.2 MeV •At foil: 65mA in 0.3-0.4 pi(rms mm mrad norm) ΔE= 100-150 keV rms

WALL

Optics and tunability

X,y rms Ratio aperture/rms above 6 everywhere

Errors and Correctors •Static alignment errors can be corrected with steerers •Jitter in the bending power supplies should be kept below 10-4•Jitter in linac energy is important for DIS and SEP acceptance

bendings 10% losses at 20% losses at

L4T.MBH.0150 /L4T.MBH.0250

±0.7% of the nominal value ±0.8% of the nominal value

L4T.MBV.0650/L4T.MBV.0750

±6% of the nominal value ±6.7% of the nominal value

BHZ20 ±0.5% of the nominal value ±0.6% of the nominal value

BHZ30 ±0.9% of the nominal value ±1% of the nominal value

AT DIS, beam size-all cases.

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

0 0.005 0.01 0.015 0.02 0.025

x, y average+ 4* RMS [m] on the scale of the DIS aperture (50X100mm)

•In 4 rms there is more than 90% of the beam

•Effect of energy painting is of the order of 5-10 mm (not included in the plot).

D=0

D=1.4

vertical aperture might be the limit for tunability in the case D=0 , unless we change yc=5.19 mm

At SMV, all cases, beam size.

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

x, y average+ 4*RMS [m] on the scale of SMV aperture (70X32 mm)

OK