1. Summary of the FCAL Workshop Cracow, February 12-13
Ch.Grah
HH-Zeuthen Meeting
2nd March 2006

2. FCAL Meeting Overview
FCAL collaboration meeting February at the Institute of Nuclear Physics PAN, Cracow
30 participants from 8 nations
Will cover the luminosity and simulation part in this presentation.
W.Lange on electronics/DAQ/sensors
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

3. Reminder of the FCAL Region
BeamCal: 4 < θ < 28 mrad IP
PhotoCal
(>100m)
PhotoCal: 0.1 < θ < 0.4 mrad
LumiCal: 26 < θ < 82 mrad
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

4. Measure Luminosity – Physics Background
M.Pandurovic Simulation of Physics Background for Luminosity Calorimeter
Bhabha generator: BHLUMI integrated into
Detector simulation: BARBIE V4.1
Background generator: WHIZARD V1.40
Background are e+e  e+e- l+l- (l=e,μ)
four-lepton events
x [cm]
y [cm]
B/S: 5·10-5
‘1’,2,4 cuts’
B/S: 4·10-4
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

5. Measure Luminosity - Systematics
C.Rimbault The impact of electromagnetic deflection due to beam-beam effect on Bhabha scattering e- e+ e+ e-
 focusing of ~0.04 mrad
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

6. Bhabha deflection
NBh bef. def. = 35986
NBh added by def. = 4
NBh suppressed by def. = 132
q0 before deflection
q1 after deflection
Difference between theoretical and “real” nb of Bhabhas : -0.36%
“Bhabha suppression effect”
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

7. Measure Luminosity - Systematics
A.Sapronov Systematic effects on luminosity measurements at 2 and 20 mrad beam crossing angles x y dr
qoft
dr = 400 mm
qft(-p;p)
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

8. Findings
A.Sapronov Systematic effects on luminosity measurements at 2 and 20 mrad beam crossing angles
Comparing the systematic effects due to LumiCal inner radius deviation,
radial beam offset and LumiCal tilt we see:
- the effects are comparable ( or a little bit larger) at 20 mrad
with respect to 2 mrad, for the case when LumiCal is centered
around the outgoing beam pipe
- the effects are dramatically larger (up to three orders of magnitude)
if LumiCal is centered around the 'detector axis'.
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

9. Luminosity Measurement - Systematics
R.Ingbir Precison Luminosity Measurements
Investigating:
offsets (crosscheck with Sapronov)
magnetic field influence
bias
resolution
X (cm)
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

10. This is assuming knowing in perfect precision many parameters
Correction possible
Before correction
after correction
Y (cm) N3 N1 N4 N2
But !!!!!!
This is assuming knowing in perfect precision many parameters
X (cm)
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

11. Detectors are centered around the outgoing beam
LumiCal Summary
Recommendation for the geometry still hold true:
Detectors are centered around the outgoing beam
LumiCal
rmin=13 cm
rmax=28 cm
(Reasonable Statistics)
BeamCal
rmin=2 cm
rmax=16 cm
+ 30o blind area
(incoming beam)
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

12. BeamCal Simulation
A.Sapronov Beam parameters influence on spatial energy distribution in BeamCal
Full Geant4 simulation with flexible geometry and segmentation (simplified Bfield).
E = ΣElayer(i)
Energy/Layer distribution
20mrad, DiD
20mrad, antiDiD
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

13. BeamCal Simulation
C.Grah Fast Beam Diagnostics at the ILC Using the Beam Calorimeter
single and double parameter analysis
Quantity
Nominal Value
Precision
2mrad
20mrad
20mrad (2par) sx
553 nm
3.1
2.9
2.8
sx
5.2
7.4
7.6 sy
5.0 nm
0.3
0.2
sy
0.4 sz
300 mm
4.8
8.5
11.1
sz
3.7
6.3 εy
40x10-9mrad
1.7
4.2
4.1
4.7 Dx
17.7
9.3 10 Dy
0.5
0.6 N
2x1010
0.01 DN
0.02
0.03
ILCNOM,
20mrad DID
Extrapolation of beamstrahlung
pairs to BeamCal frontface.
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

14. More presentations from...
W. Lohmann General
S.Jadach Lesson from Bhabha scattering calculations performed for LEP
M. Karbowiak Preliminary studies of the systematic effects on theta angle reconstruction from deformed structure of LumiCal
P.Mikes Preliminary results of LumiCal simulation
B.Pawlik LumiCal simulation including sensors description
J.Lukasik Simulation of the Bhabha events using Barbie package
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I

15. For more details and all talks, visit:
HH-Zeuthen, 2nd March 2006
Ch.Grah: FCAL Workshop Summary I