H8RD22 Experiment to test Crystal Collimation for the LHC

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H8-RD22 Experimentto test Crystal Collimation
for the LHC

• Organized by Walter Scandale
• Conducted at CERN
• Geneva, 27 September 2006
• Participants included
• Italian group
• Russian group
• 1 American

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980-GEV BEAM CHANNELING
Independent simulations by V. Biryukov and Y.
Ivanov show channeling efficiencies of 90 to 95
possible.
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Crystal channeling a smart approach for primary
collimation

• A bent crystal should efficiently deflect halo
  particles away from the beam core toward a
  downstream massive absorber
• The selective and coherent scattering on atomic
  planes of an aligned Si-crystal replaces the
  random scattering process on single atoms of an
  amorphous target

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Silicon crystals
Strip Crystals have been fabricated in the
Sensors and Semiconductor Laboratory (Ferrara,
Italy) Crystal sizes 0.9 x 70 x 3 mm3
Quasi-Mosaic Crystals have been fabricated in
PNPI (Gatchina, Russia) Crystal plate sizes 1
x 30 x 55 mm3
critical angle for 400 GeV/c protons 10 µrad
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Layout scheme (not to scale)
Goniometer with crystal holders
S3
GC
S5
vacuum
vacuum
BM
BM
p
H
S6
S2
S4
Si microstrips (AMS)
Si microstrips (AGILE)
70 m

• Scintillators (S1-S6)
• Scintillating Hodoscope (H)

• Gas Chamber (GC)
• Bending Magnet (BM)

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Volume reflection (110) Si crystal simulation
results
H8 microbeam 400 GeV protons, divergence 3
µrad
Crystal bending angle a100 µrad, length S1 mm
Angular distribution
Volume reflection angle ?VR 14.3 µrad , s5.1
µrad Volume reflected fraction with ?lt0, VR 96
Volume captured fraction at the exit from the
crystal, VC about 1.5
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Channeling (110) Si crystal simulation results
H8 microbeam 400 GeV protons, divergence 3
µrad
Crystal bending angle a100 µrad, length S1 mm
Angular distribution
Deflection efficiency of channeled fraction 80
Full width of deflected fraction 20 µrad
Reduction of channeled fraction due to multiple
scattering about 6
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Scan of Strip Crystal (1)
(mm)
Orientation (111) Bending angle 200
microrad Crystal sizes 0.5 70
1.85 mm3
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Scan of Strip Crystal (1)
measured volume reflection angle 10 µrad
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Scan of Strip Crystal (2)
Orientation (110) Crystal sizes
0.9 70 3 mm3
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Scan of Quasi-Mosaic Crystal (1)
Orientation (111) Bending angle 80 microrad
Crystal sizes 30 58 0.84 mm3
measured volume reflection angle 10 µrad
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Double Reflection on Quasi-Mosaic Crystals (1)
double reflection angle 20 µrad
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Double Reflection on Quasi-Mosaic Crystals (2)
Two crystals displaced by 1 mm not perfect
alignment
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Conclusive remarks

• First observation of Volume Reflection Effect in
  bent silicon crystals with 400 GeV/c protons with
  efficiency close to unity
• Measurement of volume reflection angle 10 µrad
• First observation of Double Reflection using two
  crystals in series combined reflection angle is
  20 µrad and efficiency close to 1
• Channeling and Volume Reflection phenomena
  studied with Strip and Quasi-Mosaic Silicon
  Crystals (different fabrication techniques)
• Measurement of crystals with different
  crystalline planes orientations (111) and (110)

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Future Plans

• There was talk of a crystal workshop in a couple
  of months to propose experiments in the Tevatron
  and/or SPS to collimate channeled and volume
  reflected beams to be conducted spring 2007.
• We are proceeding with installing the crystal
  FNAL has but have many problems with inchworm
  drive.

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Extra Slides
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The beam

• Beam parameters
• Primary 400 GeV/c proton beam
• Typical beam intensity at T4 target 20 ? 1011
  ppp
• The experiment requires reduced rates lt 104-5 ppp
  (for silicon detectors DAQ)
• Beam measurements
• 10 µrad divergence
• 1 mm (r.m.s.) beam dimension at 65 m with not
  aligned crystal

Crystal not aligned
1 ch 0.110 mm
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High precision goniometric system
Silicon detector
Scintillator
Goniometer
Granite Block
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AMS Silicon Detectors

• Detector upstream of the crystal (on the granite
  block)
• 1 double-sided silicon microstrip detector
• - Resolution 10 µm in bending direction (X
  coordinate)
• - Resolution 30 µm in non-bending direction
  (Y coordinate)
• - Active area 7.0 x 2.8 cm2
• Detector downstream of the crystal (on the
  granite block)
• 1 BABY double-sided microstrip detectors (IRST)
• Resolution better than 10 µm in bending direction
  
• Resolution better than 20 µm in non-bending
  direction
• Active area 1.9 x 1.9 cm2
• DOWNSTREAM TELESCOPE (at 65 m
• from crystal location)
• 4 AMS LADDERS
• Resolution 10 µm in bending direction
• Resolution 30 µm in non-bending direction
• Active area 4 x 7 cm2

• Silicon thickness
• 300 µm

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AGILE Silicon Detectors

• Single-sided silicon strip detectors
• Built by Agile (INFN/TC-01/006)
• active area 9.59.5 cm2
• Spatial resolution 40 ?m at normal incidence
  ( 30 ?m for tracks at 11)
• Silicon thickness 410 µm

• Upstream detector (before goniometer)
• 2 silicon detectors at 90 (corresponds to 1 X-Y
  plane)

• Downstream detector 1 (at 65 m from crystal
  location)
• 4 X-Y silicon planes

• Downstream detector 2 (at 65 m from crystal
  location)
• 6 X-Y silicon planes interleaved with 300 ?m
  tungsten planes

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Scintillators and trigger system

• SCINTILLATING DETECTORS
• finger scintillators (S1,S5) 0.1 1 10 mm3
  (S1,S5) and 0.05 1 10 mm3 (S2) to choose a
  narrow beam fraction
• 1 finger scintillator (S6) 2 1 10 mm3
• scintillating Hodoscope (H) 16 strips with 3.2
  3.0 cm2 sensitive area (each strip is 2 4 40
  mm3) read-out by 16 ch. MAPMT (fast beam
  monitoring)
• 2 scintillator plates (S3,S4) 100 100 4 mm3
  used for triggering the silicon detectors
• SCINTILLATORS ELECTRONICS and TRIGGER
• programmable Trigger Logic Unit (high
  flexibility many trigger conditions possible)