update from Oct 2010 1 LINAC4 BCC 1 septembre 2011 Christian Carli Margarita Garcia Tudela Alessandra Lombardi Lutz Hein Mohammad Eshraqi LINAC4 transfer line optics M Eshraqi L Hein A Lombardi BEABP ID: 224432
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Slide1
L4 transfer line to the PSB update from Oct 2010
1
LINAC4 BCC -1 septembre 2011
Christian
Carli
, Margarita Garcia Tudela
Alessandra Lombardi
Lutz Hein, Mohammad
EshraqiSlide2
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.
Optics LayoutTunabilitySafety margins
L2
PSB
L4
↕ 2.5m
14 OCTOBRE-2010
Active elements : 5+2bendings;17+18 quads,13+11
steerers
and 1 RF cavity. Slide3
Main changes
Horizontal bending : 70 degrees from the Linac4 into the connecting tunnel are done with 3 bendings instead of 2 . Motivation : use short(er
) H bends.Vertical step : 2.5 meters between Linac4 and PBS are done on a 15 degrees slope instead of 28 degrees. Motivation : decrease the gradient in the
quadrupoles
.
LINAC4 BCC -1 septembre 2011
3Slide4
Top View proposed layout
4
BCT as far upstream
as possible
(reference value)
BCT (not too) close
to exit of bend
BCTs close
(not too) to
entrance and
exit of bend
(losses in
vertical step)
Profile monitor
(beam size critical at
entrance in vertical step)
BCT somewhere
before debuncher
Profile monitor
(momentum spread
measurement with
Special quad setting)
C. CarliSlide5
3 horizontal bends layout
BHZ.20
5
Proposed Layout
8.2m
10 m
3 horizontal magnets
Angle = 70/3 = 23.33 deg
L= 4.1m (from deflection point to the next bending
dp
)
Lmag= 870 mmLarc= 876mmρ = 2151.15 mmSlide6
Vertical stepAchromatic translating system.
Need to have 2π phase advance at zero currentThe longer the distance between the two vertical
bendings the stronger the integrated quadrupole gradient.
LINAC4 BCC -1 septembre 2011
6
5 m between
bendings
28 degrees slope
4 Tesla integrated field in the quads
10
m between
bendings
15 degrees slope
1.8 T integrated field
in the quadsSlide7
Beam dynamics (Up to BHZ.30)
7Slide8
Beam dynamics (Up to BHZ.30)
8Slide9
Beam dynamics (Up to BHZ.30)
9Slide10
ConclusionBeam dynamics has been recalculated after adapting the layout to the bending and quads design.
nominal beam quality, flexibility and sensitivity are unchanged seen from the PBS.
Needs to be verified Steering sensitivity with new layout and vacuum chamber Detail the commissioning strategy and dispersion control
LINAC4 BCC -1 septembre 2011
10Slide11
Appendix – Straight line
Reduced distance bending towards the tunnel to the dump entailed a redesign of the emittance measurement line before the dump.Make use of the “forward method reconstruction” : improved accuracy on the evaluation of
emittance from profile measurements in presence of space charge
LINAC4 BCC -1 septembre 2011
11Slide12
Emittance estimation in L4Z
Hardware: 3 semgrids. No extra quads!Minimum rms beam size is +- 1 mm -> Resolution 0.3-0.5 mm.
Location of the semgrids:- just after
quadrupole
L4T.MQF.0210
just before L4T.MBH.0250 .
2 meters after the L4T.MBH.0250
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