beam delivery system simulation and detector backgrounds
DESCRIPTION
Beam Delivery System Simulation and Detector Backgrounds. Arlington Linear Collider Workshop January 9-11, 2003. Takashi Maruyama SLAC. “Collimation Task Force”. • Compare performance of the collimation system of TESLA, JLC/NLC and CLIC. • Review spoiler/absorber settings - PowerPoint PPT PresentationTRANSCRIPT
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Beam Delivery System Simulation and Detector Backgrounds
Takashi MaruyamaSLAC
Arlington Linear Collider Workshop January 9-11, 2003
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“Collimation Task Force”
December 16 - 18, 2002
• Compare performance of the collimation system of TESLA, JLC/NLC and CLIC.
• Review spoiler/absorber settings
• Halo collimation
• Particle loss calculation
• Sync. radiation collimation
NLC: S. Hertzbach, L. Keller, T. Markiewicz,T. Maruyama, T. Raubenheimer, A. Seryi, P. Tennenbaum, M.
Woodley
TESLA: O. Napoly, N. Walker
CLIC: G. Blair, D. Schulte, F. Zimmermann
FNAL: A. Drozhdin, N. Mokhov
TRC: W. Kozanecki
December 16 – 18, 2002
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Background and collimation
• Major source of detector background: Halo particles hitting beamline components generate muons and low energy particles.Halo particles generate sync. radiations that hit VXD.Beam-gas scattering generates low energy particles.
• Collimate Halo particles:Spoilers and AbsorbersCollimation depth – (nxx, nyy)
Reduce halo size using Octupoles• What is Halo, and How much: Drozhdin’s 1/x-1/y model
Flat distribution with 50x,50x’,200y,200y’,3%E/E
Calculated halo ~10-6, but design collimation for 10-3.
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NLC Detector Masking Plan View w 20mrad X-angle
LD – 3 Tesla SD – 5 Tesla
32 mrad30 mrad
R=1 cm
Apertures: 1 cm beampipe at the IP 1 cm at Z = -350 cm
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2001 Collimation System & FF integrated design
New scheme of the Collimation Section and Final Focus with ODs
Energy collimation
Betatroncollimation
Final Focus
IP FD IP FD IP
FD
S SA SA SA A
A
FDA
Final Focuscollimation
AIP
Octupole Doublets
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Beam Delivery Systems
TESLA
JLC/NLC
CLIC
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Synchrotron radiations
FF doublet aperture 1 cm
bendsquads
Photons from quads
Photons from bends
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Sync. Radiation vs. IP
ny
nx
cm
xIP
yIP
Track particle with n• backward from IP to AB10.
Track particle to IP and generate sync. radiations.
Find sync. radiation edge as a function of (nx, ny). nx = 18.5 x+, 17.2 x-
ny = 50.9 y
Find AB10 and AB9 apertures as a function of (nx, ny)
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Sync. Radiations at IP
X (cm)
Y
X (cm)
Log10(E) (GeV)
Quad
Bend
.3 Ne-
<E>=4.8 MeVQuad
Bend
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Spoiler/Absorber Settings for NLC
Spoilers/Absorbers Settings for NO OCT
Half aperturesX Y (um) xy
Sp1 ~ SP4 settings with OCT x2.5
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Spoiler/Absorber Settings
TESLA
CLIC
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Halo ModelX’
X (cm) Y (cm)
Y’
10-5
y (cm)
x (cm)
1/x and 1/y density over
Ax = (6 – 16)x and
Ay = (24 – 73)y – NLC/CLIC
Ax = (7 – 18)x and
Ay = (40 – 120)y – TESLA
E/E = 1% (Gaussian)
Halo rate 10-3
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Particle loss distribution in NLC
Z (m)
OCT-OFF
OCT-ON
42% to IP
82% to IP
ESP
EAB
AB10
AB7
DP2
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Integral Particle Loss Distribution
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Integral Particle Loss Distribution NLC/TESLA/CLIC
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250 GeV/beam Muon Endcap Background
Engineer for 10-3 Halo
Bunch Train =1012
Calculated Halo is 10-6
CollimationEfficiency 105
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Muon Background
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Beam Gas Scattering
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Detector Background from Beam Gas Scattering
At 50 nT, 8.5 hits/train within +/- 15 m of IP2.5 hits/train on 1.2 cm VXD.
If the vacuum is reduced to 1 nTin the last 250 m of IP,0.2 hits/train within +/- 15 m of IP0.05 hits/train on 1.2 cm VXD.
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Summary
• “Collimation Task Force” has been studying the beam delivery system of TESLA, JLC/NLC and CLIC.
• FF absorbers are set so that no sync. radiations hit the detector apertures.
• Assuming 10-3 halo, the particle loss is < 10-8 in FF and the muon background is tolerable.
• Octuples allow x2.5 looser spoiler settings.• Beam gas background in VXD is 0.05 hits/train
if the vacuum is 1 nT.