1. Luminosity and beam calorimeter report E. Kouznetsova, DESY

2. LAT calorimeter options
L.Suszycki, Cracow
Forward Calorimetry WG, Amsterdam, 31 March 2003

3. LAT luminosity measurement
Essential for precise luminosity measurement is a precise angle measurement of the Bhabha scattered electrons.
L/L = needs min = 1.4 rad
The standard (TDR) setup enables only
0.2 – 0.3 mrad accuracy with the price of channels.
We try
The standard setup improvements
and to consider alternative geometry setups:
Flat LAT
Stripped LAT
Amsterdam 31. March ‚03
L.Suszycki, Cracow

4. Improved LAT geometry Angle reconstruction using All sensors :
=~0.9 mrad
Every 4th sensor :
=~1.1 mrad
Every 10th sensor :
=~1.5 mrad
Improvements comparing to the Prague results:
Silicon sensors arranged in planes
Non-projective cylinders of equal height
It is resonable to apply fine segmentation to a fraction of cylinders only
Amsterdam 31. March ‚03
L.Suszycki, Cracow

5. Leackage makes
precision Lumi hard
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

6. Flat LAT geometry Sergey Kananov, Tel Aviv Angle reconstruction
All cylinders start at
z=136 cm
7, 14, 18 or 56 cylinders assumed
Conical projective geometry is kept (TDR)
Gain in angle resolution = 2.5 at price of increasing of #channels of factor 56/14=4!
Amsterdam 31. March ‚03
L.Suszycki, Cracow

7. Flat LAT shower maximum method Sergey Kananov, Tel Aviv
Only rings near the shower maximum at ring #8 are significant for theta reconstruction:
1, 3, 5, 7, 10, 16 or 20 „active” rings
One can reach better angular resolution with similar #channels:
Uniform: 14 x 30 x 24 = => 0.18 mrad
5 rings 2-fold granulated: => 0.13 mrad
5 rings 4-fold granulated: => 0.09 mrad
Amsterdam 31. March ‚03
L.Suszycki, Cracow

8. Stripped LAT geometry Bogdan Pawlik, Cracow
= gen - rec (radians)
vs.
strip layer („cylinder”)
Silicon 1mm strips arranged in 20 cones to read r and z x 256 strips + 20 cones to read φ x 72 strips => 6560 channls in total
 = ~0.9mrad
at 9st layer
Amsterdam 31. March ‚03
L.Suszycki, Cracow

9. LAT conclusions
Preliminary results on alternative LAT geometry are obtained
Much more MC work is necessary to get closer to the required acurracy of the angle measurement
Still awaiting for the Flat Mask decision
Amsterdam 31. March ‚03
L.Suszycki, Cracow

10. Challenges in Lumi Measurement
Some studies of sensitivity to systematic uncertainties
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

11. Method BHLUMI (Ver. 4.04) No Detector Simulation Generate an event
 calculate coordinates on calorimeter
 apply systematic shifts
 recalculate coordinates
 apply selection cuts
 count events  Lumi
E+, E- > 0.8 Ebeam
Acol < 11.5o
30 mrad < θ+ < 75 mrad
30 mrad < θ- < 75 mrad
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

12. Offset of Beams from Axis
Lin. Coeff. ≈ 0
Quadratic Coeff.:
Δoffset < 200 μm
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

13. Inner Radius of Calorimeter :
Longitudinal Distance of Calorimeters :
ΔL/L ≈ / μm
ΔL/L ≈ / mm
z+ - z- < 60 μm
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

14. Conclusions To achieve ΔL / L ≈ 10-4: Beam Offsets: < 200 μm
Inner Radius of Cal < 0.75 μm
Distance of Cals < 60 μm
Center-of-Mass Energy: process dependent
but that‘s not all yet
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

15. LAT detector alignment
Wojciech Wierba
Institute of Nuclear Physics
Cracow Poland
Jerzy Zachorowski
M. Smoluchowski Institute of Physics
Jagiellonian University
Photonics Group
Amsterdam 31. March ‚03
Wojciech Wierba Cracow, Poland

16. LAT alignment There are four tasks:
Measurement of the beam pipe dimensions in the lab.
Radial metrology and mechanical design of the LAT detectors.
Initial alignment of the LAT detectors in the forward region.
On line system to measure displacement of the LAT detectors.
The luminosity measurement requires precision alignment of the LAT detectors and stable, precision placement in reference to the interaction point. The beam pipe becomes as a suitable reference because the Beam Position Monitors are mounted inside the vacuum pipe. This allows us to correct the real LAT detectors position in respect to the beam position.
Amsterdam 31. March ‚03
Wojciech Wierba Cracow, Poland

17. On line system to measure displacement of the LAT detectors
The Photonic sensor for the z (along the beam) distance measurement:
Small probe head, just end of the ~3mm fiber.
Lightweight probe to be attached to the flange of the beam pipe.
All electronics and laser can be placed outside the TESLA detector.
Only fibers have to be feed near the LAT detector.
Continuous laser beam is not necessary i.e. power fault, laser change/repair.
Amsterdam 31. March ‚03
Wojciech Wierba Cracow, Poland

18. On line system to measure displacement of the LAT detectors
Fine pixel CCD sensor to measure x, y and  position :
The CCD detector should be glued to the rear face of the calorimeter. The laser beam can be distributed via optical fiber. The laser spot will be formed by collimator or optics.
Advantages :
Small and lightweight collimator/optics to be attached to the flange of the beam pipe.
Laser can be placed outside the TESLA detector.
Continuous laser beam is not necessary i.e. power fault, laser change/repair.
Only some cables and fiber have to be feed near the LAT detector.
Problems :
Radiation hardness of the CCD sensor and electronics. The CCD will be placed between rear side of the LAT calorimeter and tungsten shield and probably the radiation dose will be not so high.
Background from the particles. The position measurement can be done in the time slot between trains when beams are not present. The speed of the CCD sensor is sufficient to do that.
Amsterdam 31. March ‚03
Wojciech Wierba Cracow, Poland

19. First results from silicon and diamond sensors
K. Afanasiev1, I. Emeliantchik1,
E. Kouznetsova2, W. Lohmann2,
W. Lange2
1 NC PHEP, Minsk
2 DESY Zeuthen

20. Test Set Up or ADC Amsterdam 31. March ‚03 E. Kouznetsova DESY Zeuthen
discr
delay in
gate
ADC PA
diamond Sr
Amsterdam 31. March ‚03
E. Kouznetsova DESY Zeuthen

21. Signals from 90Sr – silicon and diamond :
(mip)
Diamond
(whole b-spectra)
Diamond
(noise)
Diamond
Amsterdam 31. March ‚03
E. Kouznetsova DESY Zeuthen

22. Problems and further steps :
Noise level is not optimal for signal/noise separation
(ENC ≈700 e)
Possible solutions :
Noise optimization of the existing preamplifier
Switch to Amptek A250 (noise expected ≤ 350 e)
New trigger scintillator matching the size of the sensor
New diamond samples :
Fraunhofer Institute (Freiburg) :
(12 x 12 mm)
300 and 200 mm
Different surface treatments
Prokhorov Institute (Moscow) - Dubna group
Amsterdam 31. March ‚03
E. Kouznetsova DESY Zeuthen

23. New Design of the Mask For L* = 3 m performance of the
mask calorimeters is doubtful
For larger L* things look easier
Question: How much L* do we
need?
Achim Stahl
DESY Zeuthen

24. Achim Stahl DESY Zeuthen
Fake Photons
Leackage makes
precision Lumi hard
Too close to
beamstrahlung
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen

25. L* approx. 4 meters Advantages
Luminosity: More likely to achieve 0.01 %
No fakes can scatter from mask into ECal
Vacuum much better, large orfice, bellow, valve
Space for electronics available
Better separation of outer Cal from beamstrahlung
(5cm -> 8cm)
Hermetic to 3.9 mrad (was 5.5 with gaps)
Shintake monitor taken into account
L* approx. 4 meters
Amsterdam 31. March ‚03
Achim Stahl DESY Zeuthen