Experimental  Setup of the H8-RD22 Experiment

Massimiliano Fiorini(on behalf of the H8-RD22 Collaboration)

University of Ferrara – INFN Ferrara

CARE HHH 2007 WorkshopCrystal Channeling for Large Colliders: Machine and

Physics Applications

CERN – 22 March 2007

Outlook Experiment in the H8 beam line of the SPS

north area Silicon crystals Experimental layout High precision goniometric system Proton Beam Tracking detectors

AMS microstrips detectors AGILE microstrips detectors Parallel plate chamber

Scintillators and trigger system Crystal alignment and angular scans

Concluding remarks

Crystals sizes: 0.9 × 70 × 3 mm3 and 0.5 × 70 × 3 mm3

beam

Main

ben

din

g

Anticlastic bending

Strip silicon crystals

Strip Crystals have been fabricated in the Sensors and Semiconductor Laboratory (U. of Ferrara)

Mechanical bending exploits anticlastic forces

Crystal plate sizes: ~ 1 × 30 × 55 mm3

critical angle for 400 GeV/c protons: θc ≈ 10

μrad

O.I.Sumbaev (1957)

Quasi-mosaic bending

An

ticla

stic

ben

din

g

Main bending

R

Quasy-mosaic silicon crystalsQuasi-Mosaic Crystals fabricated in

PNPI (Gatchina, Russia) mechanical bending of the crystal

induces bending of the atomic planes (initially flat and normal to large faces of plate) due to anisotropy

depends on the choice of crystallographic plane and on the angle of n111 respect to the crystal face

H8-RD22 apparatus

S1

Si microstrips (AGILE)

S3 GCS5

vacuum vacuum

Si microstrips (AMS)

p

S2

70 m

HS4

S6B5 B6

Goniometer with crystal holders

Scintillators (S1-S6) Scintillating Hodoscope (H)

Bending Magnets (B5-B6) Gas Chamber (GC)

Proton beam

CERN SPS H8 beamline Primary 400 GeV/c

proton beam Typical beam intensity at

T4 target: ~20 × 1011 ppp

The experiment required reduced rates ~5 × 104 ppp

Measurement resultsMeasurement results ~8 μrad divergence ~2 mm beam spot size at

crystal location μrad

Silicon detector

Goniometer

Granite Block

CrystalsScintillator

High precision goniometer

Goniometer (1)

two translational stages 2 μm bidirectional

repeatability full range of 102 mm

(upper stage) and 52 mm (lower stage)

one rotational stage 360° rotation 1.5 μrad accuracy 1 μrad repeatability

Rotation axis of the goniometer

Crystal holder Crystal holder

Goniometer for planar channeling

Rotation axis of the goniometer

Linear stage to put the crystal holder on rotational axis of thegoniometer

Linear stage to put the goniometer on the beam

Rotation axis of the goniometer

Proton beam

Rotation axis of the goniometer

Rotational stage for the alignement of the crystal

with the beam (planar channeling)

Proton beam

Rotation axis of the goniometer

Rotational stage also allowsthe change of the crystalwith the rotation of 180°

Proton beam

Goniometer (2)

Goniometer (3)Interferometricmeasurements

capability to return to the defined position within 1.5 μrad

± 1 μrad angular steps

Silicon thickness: 300 μm

AMS silicon detectorsDetector 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 × 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 × 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 × 7 cm2

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

AGILE silicon detector

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

Gas chamber and scintillators Gas Chamber

Parallel plate chamber 0.6 12.8 mm2 active area filled with Ar 70% + CO2 30% 64 strips (pitch equal to 200 μm) mounted on X-Y table able to withstand rates up to 108

ppp

Scintillating detectors Finger scintillators: 0.1 1 10

mm3

Scintillating hodoscope: 16 strips with 2 4 30 mm3 read-out by MAPMT (fast beam monitoring)

Scintillator plates 100 100 4 mm3 used for triggering silicon detectors

Laser pre-alignment

laser beam, parallel to proton beamline

measurement of laser beam deflection (1 mm precision)

considering prism-crystal distance (~1 m) and prism-laser distance (~ 4 m), accuracy of crystal pre-alignment was about 0.1 mrad

crystal

screen

LASER

pentaprism

Angular scan: example Fast identification of channeling position with parallel

plate chamber

Fine step angular scan

Detailed angular measurement with silicon detectors

All data are stored to disk for offline analysis

Conclusive remarks SPS H8 beamline excellent facility for crystal

channeling and volume reflection studies (very low beam divergence ~8 μrad)

Goniometric system with ~1 μrad precision and the possibility to host two crystals

Set-up of tracking system with excellent spatial resolution and minimal material budget

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)

SPARES

Double reflection on Quasi-Mosaic crystal

Experimental setup:

exploited rotational stage for off-axis alignment of the first crystal (preliminary scan)

used upper linear stage for alignment of second crystal

many steps for finding perfect alignment conditions