1. LumCal, BeamCal and GamCal
William Morse - BNL
SiD SLAC October W.M. Morse

2. FCAL Meeting Oct. 17 MPI Munich
W. Lohmann (DESY Zeuthen) spokesman
W. Morse (BNL) beam diagnostics (BeamCal/GamCal) coordinator
B. Pawlik (Cracow) simulations
W. Lange (DESY) sensors
Cracow TBD electronics
W. Wierba (Cracow) LumCal laser alignment
SiD SLAC October W.M. Morse

3. SiD SLAC October 28 2006 W.M. Morse
U.S. Forward
BNL PI: W. Morse
F. Lanni, D. Lissauer: BeamCal readout issues
Z. Li: radiation damage issues
B. Parker: machine interface issues
Yale PI: M. Zeller
G. Atoian, V. Issakov, A. Poblaguev: GamCal design issues
Colorado PI: U. Nauenberg: SUSY studies
SiD SLAC October W.M. Morse

4. BeamCal Radiation Damage
10MGy/yr from beam-strahlung electrons
21014 n/cm2 per yr, mainly from giant dipole resonance (10-40 MeV NnN*)
Zheng Li (BNL Instrumentation) recommends high resistivity MCZ Si cooled to -10C
They have tested diamond. It does not pass. They plan to test Ga-Ar
SiD SLAC October W.M. Morse

5. 14mrad with Anti-solenoid
SiD SLAC October W.M. Morse

6. SiD Anti-Solenoid Magnet
Brett Parker (BNL) design – see VLCW06 talk
Lower B affects pairs and also backsplash to vertex detector
SiD SLAC October W.M. Morse

7. Achieving the Design Luminosity Will Be a Challenge
Bunch P- (t) {N, E, x, y, z, x, y, z, xy, x, y}
Bunch P+(t) {N, E, x, y, z, x, y, z, xy, x, y}
Instantaneous Luminosity: y x
SiD SLAC October W.M. Morse

8. SiD SLAC October 28 2006 W.M. Morse
Run Time Measurements
Beam-beam deflections (pickup electrodes)
Beam-strahlung gammas (GamCal)
Beam-strahlung pairs (BeamCal)
We need robust and complementary information
SiD SLAC October W.M. Morse

9. SiD SLAC October 28 2006 W.M. Morse
Beam-strahlung
F = e(E + cB). Bmax  1KT
Instantaneous power radiated:
P  3% Pe N  1.5Ne
Bethe-Heitler: e → e e+e-
BH  38 mb
<E>  1GeV
Landau-Lifshitz: ee → ee e+e-
LL  19 mb
<E>  0.15GeV
Other processes much smaller
C. Rimbault et al., Phys Rev ST AB 9, (2006).
SiD SLAC October W.M. Morse

10. SiD SLAC October 28 2006 W.M. Morse
Bethe-Heitler Pairs
e → e e+e-
For left and right detectors separately: N+/xy and N-/xy.
Question: How well does this really work? Answer: Needs simulation.
SiD SLAC October W.M. Morse

11. Landau-Lifshitz Pairs
ee → eee+e-
For left and right detector
equally
1 GeV
SiD SLAC October W.M. Morse

12. SiD SLAC October 28 2006 W.M. Morse
Simulations
W. Morse (BNL)
W. Lohman, E. von Oelson, and M. Ohlerich (DESY Zeuthen)
To Be Submitted as an ILC Note
Guinea Pig simulations varying some of the 500 GeV ILC bunch parameters around nominal values
SiD SLAC October W.M. Morse

13. SiD SLAC October 28 2006 W.M. Morse
Vertical offset
E BeamCal (TeV)
SiD SLAC October W.M. Morse

14. SiD SLAC October 28 2006 W.M. Morse
Vertical Offset
R (10-6)
SiD SLAC October W.M. Morse

15. SiD SLAC October 28 2006 W.M. Morse
Bunch Width
BeamCal
E (TeV)
R 10-6
SiD SLAC October W.M. Morse

16. SiD SLAC October 28 2006 W.M. Morse
Comparison
Sign of dE/d(bunch characteristic) at design values. Note that all five lines are different, which means complementary information.
Parameter
Pairs
Gammas
Ratio
X offset
0 (max) z - 0 y x
Y offset
0 (min)
SiD SLAC October W.M. Morse

17. SiD SLAC October 28 2006 W.M. Morse
Bunch Height
SiD SLAC October W.M. Morse

18. SiD SLAC October 28 2006 W.M. Morse
Bunch Length
SiD SLAC October W.M. Morse

19. Is There More Info in BeamCal?
T.Tauchi,K.Yokoya
Phys Rev E51,6119(95)
6<r<7cm azimuthal dist
But, Moliere dia. 2cm!
Also, 1 Bhabha/BX!
Thus we need more simulation to show that it is robust enough.
Christian Graf (DESY Zeuthen) has started.
SiD SLAC October W.M. Morse

20. Robust and Complementary
Luminosity, ie. R, is low. Note that all columns are different, ie. complementary information.
Detector
X offset
Y offset x y
PUE x y
Normal
E GamCal
Low
High
E BeamCal
SiD SLAC October W.M. Morse

21. GamCal Detector Concepts
14mrad crossing angle
10-6 X0 gas jet to convert beam-strahlung gammas into e+e- pairs
Magnet to separate electrons from positrons
Detect “wrong sign” particles
Probably need to be after E/P detectors at z=175m
GamCal z = 185m?
SiD SLAC October W.M. Morse

22. Large Crossing Angle GamCal
Gas jet followed by a 1m long 1.5T dipole magnetic field. Trajectories of positrons of momentum 0.1, 1, and 10 GeV/c are shown.
SiD SLAC October W.M. Morse

23. SiD SLAC October 28 2006 W.M. Morse
GamCal Backgrounds
SiD SLAC October W.M. Morse

24. SiD SLAC October 28 2006 W.M. Morse
LumCal
LumCal (20-140mrad) provides real time absolute luminosity measurement
10% every 5 minutes
Hermeticity
Need to study optimal cos range to get minimum Bhabha systematics with both beams polarized
Goal is several 10-4 accuracy systematics
SiD SLAC October W.M. Morse

25. SiD SLAC October 28 2006 W.M. Morse
OPAL Data
SiD SLAC October W.M. Morse

26. But, if both beams are polarized
Asymmetry in percent (RHS) and dN/d per year (LHS) vs. the polar angle . The error bars
on the Coulomb asymmetry correspond to 107 s running at nominal luminosity with 60%
positron polarization, and 80% electron polarization.
SiD SLAC October W.M. Morse

27. SiD SLAC October 28 2006 W.M. Morse
Conclusions
We need robust, redundant information:
Beam-beam deflections
Beam-strahlung gammas
Beam-strahlung pairs
E(pairs)/E(gammas) particularly valuable
Largely proportional to instantaneous luminosity
SiD SLAC October W.M. Morse

28. SiD SLAC October 28 2006 W.M. Morse
Conclusions
BeamCal radiation damage issues.
Readout electronics.
What is optimal region for luminosity?
Use real magnetic field with anti-solenoid for simulations.
SiD SLAC October W.M. Morse

29. SiD SLAC October 28 2006 W.M. Morse
Extra Slides
SiD SLAC October W.M. Morse

30. SiD SLAC October 28 2006 W.M. Morse
1  2 y - z +
SiD SLAC October W.M. Morse

31. SiD SLAC October 28 2006 W.M. Morse
Perfect Collisions
SiD SLAC October W.M. Morse