Status of ongoing studies for comparing 2-mrad and 20-mrad IRs

1
Status of ongoing studies for comparing 2-mrad
and 20-mrad IRs

• T. Maruyama
• SLAC

2
Beam parameters

• 500 GeV TESLA TDR
• 3.4?1034 cm-2s-1 (6.8?10-3 pb-1 / train)
• 2?1010 e-
• 2820 bunches per train _at_ 5 Hz
• 337 ns bunch spacing
• Physics rates ? (pb) events/train
• ee- ? qq 2.7 0.02
• ee- ? WW 7.6 0.05

3
Background Sources

• IP Backgrounds particles/BX Rmax gt 1 cm,
  zlt200 cm
• e/e- pairs 120K 270
• ?? ? hadrons 0.8 events
• ?? ? muons 2.3 events
• Radiative Bhabha 466K 0
• Disrupted primary beam
• Beamstrahlung photons

Tims updates for COLD

• Machine Backgrounds
• Synchrotron Radiation
• Muons Production at collimators
• Direct Beam Loss
• Beam-Gas
• Collimator edge scattering
• Neutron back-shine from Dump

4
Two Crossing Angle Schemes with SiD Detector
20 mrad
2 mrad
R 1 cm
R 2.5 cm
L 4.05 m
L 3.51 m
5
Two crossing angle schemes
20 mrad crossing
2 mrad crossing
Solenoid compensation is necessary.
QF1
QD0
Beam steering Spin precession 60 mrad 0.2
depolarization
Compensation Detector integrated dipole (DID)
Z-dependent Bx (800 Gauss max.) Larger
background Beam steering in the extraction line.
Beam extraction through QF1 coil pocket
Extraction line beam diagnostics may not work.
6
Disrupted beam in 2 mrad crossing
Seryi
2.1?107
QD0
QF1
Particle loss in QF1 3.2 of Elt0.65E0 400 Watts
7
Radiative Bhabhas in 2 mrad
QD0
QF1
Particle loss E (GeV) Power (W) QD0 1.6
?105 0.36 QF1 2.8 ?106 6.3
8
Sync radiations in 2 mr
Sync radiations hit the face of QF1
Disrupted beam with sync photons
RED halo, upstream quads GREEN halo, QD0 BLUE
disrupted beam, QD0
Beam can be extracted through QF1 coil
pocket. QF1 fringe field 3 kGauss.
9
Pairs at Z 315 cm
20 mrad w compensation
20 mrad w/o compensation
2 mrad
r 2 cm
X (cm)
10
Pairs
Rmax distribution
VXD hits
272 e/e- / BX
VXD Forward tracker
1.2 e/e- /BX
Barrel Tracker ECAL
???hadrons 1 evt/BX 2 VXD hits ???muons 2
evt/BX 2 VXD hits
11
Tracker Backgrounds
Forward
Barrel
Background in Si Tracker is small lt 5
hits Forward Layer 1 has 21 hits.
12
To do

• 20 mrad
• Solenoid compensation
• Yuris new extraction line
• 2 mrad
• Yuris new extraction line
• Different QF1 design