For K s =20.86 m -2

New Progress of the Nonlinear Collimation
System for CLIC:
Characterization, Performance
and Optimization
Javier Resta Lopez
Angeles Faus-Golfe
Daniel Schulte
Rogelio Tomás
Frank Zimmermann
7 February 2006
Javier Resta Lopez
CLIC meeting
Contents
Nonlinear energy collimation system for CLIC
Tracking studies
Luminosity as function of the skew sextupole strength
Beam peakdensity at the spoiler
Particles distribution at the spoiler
Optics optimization
Schematic
Preliminary results using thin multipoles
Luminosity improvement
Conclusions
7 February 2006
Javier Resta Lopez
CLIC meeting
Nonlinear energy collimation system for
CLIC
Energy collimation
using a pair of skew
sextupoles and a single
spoiler
Beam Delivery System
of the NEW4.1 optics
Dx
-Dx
See presentation by A. Faus-Golfe
7 February 2006
Javier Resta Lopez
CLIC meeting
Tracking studies
Luminosity as function of the skew sextupole strength
7 February 2006
Javier Resta Lopez
CLIC meeting
Tracking studies
Beam peakdensity at the spoiler
For Ks=20.86 m-2
Δ=1.3 %
Average energy offset
Limit density for spoiler survival: densitylimit = 46.42 x 109/mm2 per bunch
7 February 2006
Javier Resta Lopez
CLIC meeting
Tracking studies
Particles distribution at the spoiler
Horizontal plane:
ax=1.103 mm
δ0=1%
a x  Dx , spoiler
Collimation cut
7 February 2006
Javier Resta Lopez
CLIC meeting
ay 
1
R34 K s Dx2, sext 2
2
Tracking studies
Particles distribution at the spoiler
Vertical plane:
ay=1.669 mm
Collimation cut
7 February 2006
Javier Resta Lopez
CLIC meeting
δ0=1%
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
7 February 2006
Javier Resta Lopez
CLIC meeting
Collimation gap
ay=1.669 mm
For a beam with 3% full width energy spread
ax=1.103 mm
7 February 2006
Javier Resta Lopez
CLIC meeting
Optics optimization
Schematic
Two additional multipoles for local cancellation of the
higher order aberrations
•
•
•
Skew sextupoles: K2L =20.86 m-2
Skew octupole:
K3L= -5464.93 m-3
Normal sextupole: K2L = -0.8 m-2
7 February 2006
Javier Resta Lopez
CLIC meeting
Thin multipoles have been
used for a first test !
Optics optimization
Preliminary results using thin multipoles:
Fourth order
Second order
Third order
See presentation by Rogelio Tomás
7 February 2006
Javier Resta Lopez
CLIC meeting
Optics optimization
Luminosity improvement:
For an integrated skew sextupole strength Ks=20.86 m-2
7 February 2006
Javier Resta Lopez
CLIC meeting
Conclusions
A skew sextupole integrated strength of ≈ 20 m-2 has been chosen. For this value the
spoiler survival is guarantee for off-momentum beams (> 1 %).
The chromatic behavior of the optics has been characterized. Good agreement
between the simulated horizontal and vertical rms beam sizes at the spoiler as a
function of the skew sextupole strength and the analytical expressions.
Dominant chromatic aberrations of second, third and fourth order are found. The
luminosity is degraded with the excitation of the skew sextupole.
A local cancellation of higher order aberrations was made using two additional thin
multipoles: a skew octupole and a normal sextupole. The luminosity was improved
by more than a factor 2.
Ongoing studies: consider real spoiler and absorbers and study the collimation
efficiency by means of simulation with the codes BDSIM, SIXTRACK or MARS.
7 February 2006
Javier Resta Lopez
CLIC meeting