IP Instrumentation

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IP Instrumentation

• Measurement of
• Luminosity (precise and fast)
• Energy
• Polarisation

Wolfgang Lohmann, DESY
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Precise Luminosity Measurement
Gauge process Bhabha Scattering
Device LumiCal 26 lt q lt 82 mrad
BeamCal
300 cm
VTX
L 4m
Beampipe
FTD
IP
Accuracy (from Physics) O(lt10-3)
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Requirements on the Mechanical Design
lt 4 µm
Requirements on Alignment and mechanical
Precision (MC simulations, BHLUMI)
Inner Radius of Cal. lt 4 µm Distance
between Cals. lt 100 µm Radial beam
position lt 0.6 mm

• lt 0.6 mm

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Beam Tilt
Beam Size
No effect
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Performance Simulations for ee- ee-(g)
Simulation Bhwide(Bhabha)CIRCE(Beamstrahlung)be
amspread
Event selection acceptance, energy balance,
azimuthal and angular symmetry.

• Constant value

• 4 layers

11 layers
15 layers
10 rings
20 rings
10 rings

• More in the talks by Halina Abramowicz

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20 mrad crossing angle
Beamstrahlung pair background using serpentine
field
Number of Bhabha events as a function of the
inner Radius of LumiCal
250 GeV
A design for 20 mrad crossing angle will be
done (needs time)
Background from beamstrahlung
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Concept for the Mechanical Frame
Decouple sensor frame from absorber frame
Sensor carriers
Absorber carriers
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Fast Lumi Measurement and Beam Diagnostics
Use Electrons from Rad. Bhabha events
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Fast Lumi Measurement and Beam Diagnostics
Trajectories of off momentum electrons in the
first dublett
Energy and spatial distributions
Needs a spectrometer there
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Fast Lumi Measurement and Beam Diagnostics
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Beam Parameter Determination with BeamCal

• ee- Pairs from Beamstrahlung are deflected
  into the BeamCal

Zero (or 2 mrad) crossing angle

• 15000 ee- per BX 10 20 TeV

(10 MGy per year)

• direct Photons for q lt 200 mrad

GeV
20 mrad Crossing angle
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Beam Parameter Determination with BeamCal
Observables
total energy first radial moment thrust
value angular spread L/R, U/D F/B asymmetries
Quantity Nominal Value Precision
sx 553 nm 1.2 nm
sy 5.0 nm 0.1 nm
sz 300 mm 4.3 mm
Dy 0 0.4 nm
vs 500 GeV
zero or 2 mrad Crossing angle
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Beam Parameter Determination with BeamCal
Observables
total energy first radial moment thrust
value angular spread L/R, U/D F/B asymmetries
20 mrad crossing angle
Quantity Nominal Value Precision
sx 553 nm 4.8nm
sy 5.0 nm 0.1 nm
sz 300 mm 11.5 mm
Dy 0 2.0nm
Also simultaneous determination of several beam
parameter is feasible, but Correlations! Analysis
in preparation
PRELIMINARY!
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Beam Parameter Determination with BeamCal
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Beam Parameter Determination with BeamCal
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and with PhotoCal
Photons from Beamstrahlung
Heavy gas ionisation Calorimeter
nominal setting (550 nm x 5 nm)
L/R, U/D F/B asymmetries of energy in the
angular tails
Quantity Nominal Value Precision
sx 553 nm 4.2 nm
sz 300 mm 7.5 mm
Dy 0 0.2 nm
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Technologies for the BeamCal

• Radiation Hard
• Fast
• Compact

Heavy crystals
W-Diamond sandwich
sensor
Space for electronics
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Detection of High Energy Electrons and
Photons (Detector Hermeticity)
vs 500 GeV
Single Electrons of 50, 100 and 250 GeV,
detection efficiency as a function of R (high
background region) (talk by V. Drugakov and P.
Bambade)
Detection efficiency as a function of the
pad-size (Talk by A. Elagin)
Red high BG blue low BG
Message Electrons can be detected!
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• Detection of High Energy Electrons and Photons

Efficiency to identify energetic electrons and
photons (E gt 200 GeV)
Realistic beam simulation
vs 500 GeV
Includes seismic motions, Delay of Beam
Feedback System, Lumi Optimisation etc. (G.
White)
Fake rate
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Sensor prototyping, Diamonds
Pads

Pm12
May,August/2004 test beams CERN PS Hadron beam
3,5 GeV 2 operation modes Slow extraction
105-106 / s fast extraction 105-107 / 10ns
(Wide range intensities) Diamond samples
(CVD) - Freiburg - GPI (Moscow) - Element6
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Diamond Sensor Performance
Linearity Studies with High Intensities (PS
fast beam extraction) 105 particles/10 ns
Response to mip
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Upstream momentum spectrometer
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ESA Test Beam Plans for 2005/2006
2x1010 electrons per bunch _at_ 28.5 GeV (ILC buch
charge and length) Compare different measurments
(this spectrometer, A- line BPMs, Synchrotron
spectrometer) Accuracy goal lt 100 ppm Proof of
principle!
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Energy Measurement
Downstream SR spectrometer
Energy spectrum After bunch crossing

• Goals
• peak position,
• width,
• tail

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Downstream SR spectrometer
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Downstream SR spectrometer
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Polarimetry
Upstream polarimeter
Downstream polarimeter
Document on polarimetry design in Feb 2006
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The needs from Detector and Machine side are
different. Lets find solutions