Luminosity and beam calorimeter report E. Kouznetsova, DESY

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Luminosity and beam calorimeter reportE.
Kouznetsova, DESY
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LAT calorimeter options

• L.Suszycki, Cracow
• Forward Calorimetry WG, Amsterdam, 31 March 2003

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LAT luminosity measurement

• Essential for precise luminosity measurement is a
  precise angle measurement of the Bhabha scattered
  electrons.
• ?L/L 10-4 needs ??min 1.4 ?rad
• The standard (TDR) setup enables only
• 0.2 0.3 mrad accuracy with the price of 13440
  channels.
• We try
• The standard setup improvements
• and to consider alternative geometry setups
• Flat LAT
• Stripped LAT

L.Suszycki, Cracow
Amsterdam 31. March 03
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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
L.Suszycki, Cracow
Amsterdam 31. March 03
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Leackage makes precision Lumi hard
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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Flat LAT geometry

• Sergey Kananov, Tel Aviv
• Angle reconstruction

• All cylinders start at
• z136 cm
• 7, 14, 18 or 56 cylinders assumed
• Conical projective geometry is kept (TDR)

Gain in angle resolution 2.5at price of
increasing of channels of factor 56/144!
L.Suszycki, Cracow
Amsterdam 31. March 03
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Flat LAT shower maximum methodSergey 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 10080gt 0.18 mrad
• 5 rings 2-fold granulated 11760gt 0.13 mrad
• 5 rings 4-fold granulated 15120gt 0.09 mrad

L.Suszycki, Cracow
Amsterdam 31. March 03
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Silicon 1mm strips arranged in20 cones to read
r and z x 256 strips20 cones to read f x 72
strips gt 6560 channls in total
Stripped LAT geometryBogdan Pawlik, Cracow
?? ?gen - ?rec (radians) vs. strip layer
(cylinder)
?? 0.9mrad at 9st layer
L.Suszycki, Cracow
Amsterdam 31. March 03
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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

L.Suszycki, Cracow
Amsterdam 31. March 03
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Challenges in Lumi Measurement
Some studies of sensitivity to systematic
uncertainties
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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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- gt 0.8 Ebeam Acol lt 11.5o
30 mrad lt ? lt 75 mrad 30 mrad lt ?- lt 75 mrad
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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Offset of Beams from Axis
Lin. Coeff. 0
Quadratic Coeff. ?offset lt 200 µm
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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Inner Radius of Calorimeter
Longitudinal Distance of Calorimeters
?L/L 1.3 10-4/ µm
?L/L -0.0033 / mm z - z- lt 60 µm
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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Conclusions
To achieve ?L / L 10-4
Beam Offsets lt 200 µm Inner
Radius of Cal lt 0.75 µm Distance of
Cals lt 60 µm Center-of-Mass
Energy process dependent
but thats not all yet
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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LAT detector alignment

• Wojciech Wierba
• Institute of Nuclear Physics
• Cracow Poland
• Jerzy Zachorowski
• M. Smoluchowski Institute of Physics
• Jagiellonian University
• Photonics Group
• Cracow Poland

Wojciech Wierba Cracow, Poland
Amsterdam 31. March 03
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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.

Wojciech Wierba Cracow, Poland
Amsterdam 31. March 03
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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.

Wojciech Wierba Cracow, Poland
Amsterdam 31. March 03
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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.

Wojciech Wierba Cracow, Poland
Amsterdam 31. March 03
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First results from silicon and diamond sensors
K. Afanasiev1, I. Emeliantchik1, E.
Kouznetsova2, W. Lohmann2, W. Lange2 1 NC
PHEP, Minsk 2 DESY Zeuthen
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Test Set Up
or
E. Kouznetsova DESY Zeuthen
Amsterdam 31. March 03
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Signals from 90Sr silicon and diamond
Si (mip)
Diamond (whole b-spectra)
Diamond (noise)
Diamond
E. Kouznetsova DESY Zeuthen
Amsterdam 31. March 03
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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

E. Kouznetsova DESY Zeuthen
Amsterdam 31. March 03
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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
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Fake Photons
Leackage makes precision Lumi hard
Too close to beamstrahlung
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03
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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 -gt 8cm)
• Hermetic to 3.9 mrad (was 5.5 with gaps)
• Shintake monitor taken into account

L approx. 4 meters
Achim Stahl DESY Zeuthen
Amsterdam 31. March 03