H8-RD22 Experimentto test Crystal Collimation for

the LHCOrganized by: Walter ScandaleConducted at CERNGeneva, 27 September 2006Participants included: Italian group:Russian group:1 American:

980-GEV BEAM CHANNELINGIndependent simulations by V. Biryukov and Y. Ivanov showchanneling efficiencies of 90% to 95% possible.

Particles are channeled Lattice of crystal.

Volume Capture:

Volume reflections from atomic planes

September 2006

Walter Scandale 3/19

A bent crystal should efficiently deflect halo particles away from the beam core toward a downstream massive absorber

The selective and coherent scatteringselective and coherent scattering on atomic planes of an aligned Si-crystal replaces the random scatteringrandom scattering process on single atoms of an amorphous target

Crystal channeling: a smart approach for primary collimation

Amorphous scatterer

September 2006

Walter Scandale 4/19

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

September 2006

Walter Scandale 5/19

Layout scheme (not to scale)

• Scintillators (S1-S6)

• Scintillating Hodoscope (H)

vacuum vacuum

Goniometer with crystal holders

Si microstrips (AMS)

p

S1

S2

70 m

Si microstrips (AGILE)

S3 GC

HS4

S5

S6BM BM

• Gas Chamber (GC)

• Bending Magnet (BM)

September 2006

Walter Scandale 6/19

Volume reflection (110) Si crystal – simulation results

H8 microbeam – 400 GeV protons, divergence – 3 μrad

Angular distribution

Crystal bending angle α=100 μrad, length S=1 mm

Volume reflection angle θVR = 14.3 μrad , σ=5.1 μradVolume reflected fraction with θ<0, VR – 96%

Volume captured fraction at the exit from the crystal, VC – about 1.5%

VR

VC

September 2006

Walter Scandale 7/19

Channeling (110) Si crystal – simulation results

H8 microbeam – 400 GeV protons, divergence – 3 μrad

Crystal bending angle α=100 μrad, length S=1 mm

Deflection efficiency of channeled fraction – 80% Full width of deflected fraction – 20 μrad

Reduction of channeled fraction due to multiple scattering – about 6%

Angular distribution0

Ch

September 2006

Walter Scandale 8/19

Scan of Strip Crystal (1)

Orientation (111)

Bending angle: ~ 200 microrad Crystal sizes: 0.5 × 70 × 1.85 mm3

(mm)

September 2006

Walter Scandale 9/19

Scan of Strip Crystal (1)

measured volume reflection angle: ~ 10 μrad

September 2006

Walter Scandale 10/19

Scan of Strip Crystal (2)

Orientation (110)

Crystal sizes: 0.9 × 70 × 3

mm3

September 2006

Walter Scandale 11/19

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

September 2006

Walter Scandale 12/19

Double Reflection on Quasi-Mosaic Crystals (1)

double reflection angle: ~ 20 μrad

September 2006

Walter Scandale 13/19

Double Reflection on Quasi-Mosaic Crystals (2)

Two crystals displaced by 1 mm: not perfect alignment

September 2006

Walter Scandale 14/19

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)

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.

Extra Slides

September 2006

Walter Scandale 17/19

The beam

Beam parametersBeam parameters• Primary 400 GeV/c proton

beam• Typical beam intensity at

T4 target: ~ 20 1011 ppp

• The experiment requires reduced rates < 104-5 ppp (for silicon detectors DAQ)

Beam measurementsBeam 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

September 2006

Walter Scandale 18/19

High precision goniometric system

Silicon detector

Goniometer

Granite Block

CrystalsScintillator

September 2006

Walter Scandale 19/19

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

September 2006

Walter Scandale 20/19

AGILE Silicon Detectors

• Single-sided silicon strip detectors• Built by Agile (INFN/TC-01/006)• active area 9.5×9.5 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

September 2006

Walter Scandale 21/19

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)