# Presentation: 193749

##  H8-RD22 Experimentto 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:*
* *

- 7 March 2005

## 980-GEV BEAM CHANNELING

- Independent simulations by V. Biryukov and Y. Ivanov show
- channeling efficiencies of 90% to 95% possible.

## 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

- 7 March 2005

## 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 ****μ****rad**

- 7 March 2005

## Layout scheme (not to scale)

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

- vacuum

- vacuum

- Goniometer with crystal holders

- Si microstrips
-       (AMS)

- p

- S2

- 70 m

- Si microstrips
-     (AGILE)

- S3

- GC

- H

- S4

- S5

- S6

- BM

- BM

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

- 7 March 2005

## 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 θ**VR **= 14.3 μrad , σ=5.1 μrad
- Volume reflected fraction with θ<0, VR – 96%

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

- 7 March 2005

## 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 distribution

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## Scan of Strip Crystal (1)

- 						  Orientation (111)
- Bending angle: ~ 200 microrad                  Crystal sizes: 0.5 × 70 × 1.85 mm3

- (mm)

## Scan of Strip Crystal (1)

- measured volume reflection angle: ~ 10 μrad

## Scan of Strip Crystal (2)

- 						  Orientation (110)
-      Crystal sizes: 0.9 × 70 × 3 mm3

## 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

## Double Reflection on Quasi-Mosaic Crystals (1)

- double reflection angle: ~ 20 μrad

## Double Reflection on Quasi-Mosaic Crystals (2)

- Two crystals displaced by 1 mm: not perfect alignment

## 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)

- 7 March 2005

## 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

## The beam

**   ****Beam parameters**
- Primary 400 GeV/c proton beam
- Typical beam intensity at T4 target:  ~ **20 ******** 10****11**** ppp**
- The experiment requires reduced rates **< 10****4-5**** 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

- High precision goniometric system

- Silicon detector

- Goniometer

- Granite Block

- Scintillator

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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 9.5×9.5 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

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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)

- 7 March 2005