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Quasimosaic crystals Yu.M.Ivanov

Quasimosaic crystals

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Quasimosaic crystals. Yu.M.Ivanov. Elastic quasimosaic (Sumbaev) effect. Studied by Sumbaev in 1957 Resulted in broadening of gamma-ray diffraction peaks from bent quartz plates - PowerPoint PPT Presentation

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Page 1: Quasimosaic crystals

Quasimosaic crystals

Yu.M.Ivanov

Page 2: Quasimosaic crystals

Elastic quasimosaic (Sumbaev) effect

• Studied by Sumbaev in 1957

• Resulted in broadening of gamma-ray diffraction peaks from bent quartz plates

• Caused by bending of the reflecting atomic planes (initially flat and normal to large faces of plate) due to crystal anisotropy

• Depends on choice of

crystallographic plane and orientation angle of plate cutting relative to a normal to the chosen crystallographic plane

Figure from article: O.I.Sumbaev, Reflection of gamma-rays from bent quartz plates, Sov. JETP 32(1957)1276

Page 3: Quasimosaic crystals

Quasimosaic effect in silicon

• Calculations of deformed crystal plate done by V.M.Samsonov (Preprint No. 278, LIYaF AN SSSR, 1976).

– Resulted in predictions of elastic quasimosaic effect for some other quartz and silicon plate orientations

– Large elastic quasimosaicity for (011) plane of silicon predicted

• Zero result in the first experiments in 1999

• New calculations using Samsonov approach and new measurements:

- (111) plane, not (011) - published in JETP Letters 81, 99, 2005

Figure from article: V.M.Samsonov and E.G.Lapin, On some possibilities and pequliarities of a curved crystal use in crystal diffraction instruments, Preprint No. 587, LIYaF AN SSSR, 1980

Page 4: Quasimosaic crystals

Elastic quasimosaic in dependence on cut angle for Si

(111) plane

T – thickness of plate

k9 – deformation coefficient

= 2k9 T , where

Plate bending radius R = 1 m

( formula taken from V.M.Samsonov, E.G.Lapin, Preprint No. 587, LIYaF AN SSSR, 1980 )

Page 5: Quasimosaic crystals

Silicon cuts

Cut without quasimosaic

Cut with quasimosaic

Oriented ingot

φ

Page 6: Quasimosaic crystals

Rocking curves for Si plate with quasimosaic

before and after bending.

Quasimosaic effect in Si with X-rays

Rocking curves for Si plate without

quasimosaic before and after bending.

Page 7: Quasimosaic crystals

Shape of bent Si plate with elastic quasimosaic

Page 8: Quasimosaic crystals

Bending device

Page 9: Quasimosaic crystals

First quasimosaic silicon crystal prepared in 2002 for channeling experiment with 70 GeV protons

Page 10: Quasimosaic crystals

Layout of experiment at IHEP in April, 2002

Crystal 1Magnets

Crystal 2

Emulsion 1

S1

S2 S3

Background

Channeled_1

30 m

35 m 4.6 m

Collimator

1.3 m

Emulsion 2

Channeled_2

70 GeVp-beam

5 m

R=3 m

Page 11: Quasimosaic crystals

Profile of 70 GeV proton beam passed through the crystal measured with emulsion: superposition of channeling and volume reflection effects

Page 12: Quasimosaic crystals

Explanation of the observed picture on emulsions

Proton trajectories crossing the crystal and emulsions in horizontal plane (top view)

Page 13: Quasimosaic crystals

Samples 0.3 mm and 2.7 mm with ~0.4 mrad bending angle

Page 14: Quasimosaic crystals

Sample 10 mm with ~100 μrad bending angle

Page 15: Quasimosaic crystals

Crystals for experiment on extraction of high entensive proton

beam at IHEP

Plane (111)

Length along beam 2.65 mm

Bending angle 400 μrad

Page 16: Quasimosaic crystals

Crystal station at IHEP ring

Page 17: Quasimosaic crystals

Crystal mounted on station

Page 18: Quasimosaic crystals

Result

Beam in the U-70 ring 5.5∙1012 p

Intensity of extracted beam 4.0∙1012 p

Efficiency 70%

Page 19: Quasimosaic crystals

Experiment on observation of volume reflection effect with 1 GeV protons

at PNPI, Gatchina

Beam divergence ~ 160 μrad

Beam size ~ 0.8 mm

Critical angle for channeling ~ 170 μrad

Crystal length along beam ~ 30 μm

Bend angle of (111) planes ~ 380 μrad

Page 20: Quasimosaic crystals

One of unsuccessful attempts to bend a 30 μm crystal on 20 mm

radius

Page 21: Quasimosaic crystals

Bent crystals in bending devices

Page 22: Quasimosaic crystals

Check of crystal shape with laser

~1

m

Page 23: Quasimosaic crystals

Measurement of bending angle with X-rays

Page 24: Quasimosaic crystals

Collimator

Crystal mounted on goniometer

Page 25: Quasimosaic crystals

Horizontal profiles of the p-beam vs. crystal angle measured with

PPC

p-beam

reflection

channeling

p-beamCry

sta

l an

gle

, ste

p 6

2.5

μra

d

Channel number, step 200m

Page 26: Quasimosaic crystals

Channeling experiment with 400 GeV protons

H8 beam line

FAR_DETECTOR areaCRYSTAL area

Page 27: Quasimosaic crystals

QM2

Page 28: Quasimosaic crystals

QM2

2 4 6 8 10 120

50

100

150

200

250

300

350

400

Position, mm

Cry

stal

ang

le, m

krad

Crystal QM2

Page 29: Quasimosaic crystals

QM2

Channeling angle (68.2 0.4) μrad

Volume reflection deflection (12.7 0.6) μrad

Volume capture ε (1.8 0.7) %

Page 30: Quasimosaic crystals

QM1

Page 31: Quasimosaic crystals

QM1

2 4 6 8 10 120

20

40

60

80

100

120

140

160

180

200

Position, mm

Cry

stal

ang

le, m

krad

Crystal QM1

Page 32: Quasimosaic crystals

QM1

Channeling angle (77.0 0.4) μrad

Volume reflection deflection (11.6 0.8) μrad

Volume capture ε (2.6 0.8) %

Page 33: Quasimosaic crystals

QM2+QM1

Page 34: Quasimosaic crystals

QM2+QM1

2 4 6 8 10 120

50

100

150

Position, mm

Cry

stal

ang

le, m

krad

Crystal QM1-QM2

Page 35: Quasimosaic crystals

QM2+QM1

Channeling angle

Volume reflection deflection (23.4 0.7) μrad

Volume capture ε (5 1) %

Page 36: Quasimosaic crystals

QM3

Page 37: Quasimosaic crystals

QM3

2 4 6 8 10 120

20

40

60

80

100

120

140

160

180

Position, mm

Cry

stal

ang

le, m

krad

Crystal QM3

Page 38: Quasimosaic crystals

QM3

Channeling angle (72.7 0.8) μrad

Volume reflection deflection (11.9 0.7) μrad

Volume capture ε (5 1) %

Page 39: Quasimosaic crystals

QM4

Page 40: Quasimosaic crystals

QM4

2 4 6 8 10 120

20

40

60

80

100

120

140

160

180

Position, mm

Cry

stal

ang

le, m

krad

Crystal QM4

Page 41: Quasimosaic crystals

QM4

Channeling angle (120.0 0.4) μrad

Volume reflection deflection (12.7 0.5) μrad

Volume capture ε (4.4 0.7) %

Page 42: Quasimosaic crystals

Design: sequence of quasimosaic crystals cut from a

single initial plate

p

1 Si plate 0.3 x 30 x 60 mm3

12 Si plates 0.3 x 8 x 14 mm3

Page 43: Quasimosaic crystals

Check of plate wedging with optical goniometer

Page 44: Quasimosaic crystals

Prototype assembly from 5 plates

Page 45: Quasimosaic crystals

0

1000

2000

3000

4000

5000

6000

7000

14,85 14,90 14,95 15,00 15,05 15,10 15,15 15,20 15,25

Check with narrow X-ray beam

ΔN

Δθ≈0.017x ΔN μrad

Δθ < 40 μrad

X, mm

N,

coun

ts

ΔX

N1

N2

Δθ

ΔN=N2-N1

ΔX

Page 46: Quasimosaic crystals

Need to provide or to compensate plate wedging

Page 47: Quasimosaic crystals

Realization with evaporation technique

Al-layer of 0.14 μm thickness

Δθ = 0.14 μm / 12 mm = 12 μrad

Page 48: Quasimosaic crystals

Further steps

• to improve prototype assemly for experimental run in May’07 at CERN

• to prepare larger plates and assemble them for experiments at CERN and IHEP in the Fall’07