Transverse Beam Size Measurements at ALBA Synchrotron Light

ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
Transverse Beam Size Measurements at
ALBA Synchrotron Light Source
Laura Torino
[email protected]
September 24, 2014
Pisa, Italy
100°Congresso Nazionale SIF
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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ALBA S.L.S.
PINHOLE
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Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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ALBA
The Facility
I
High radiation flux
I
High brilliance
I
Wide radiation spectrum
I
Tunability
I
Defined polarization
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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ALBA
The Facility
I
Energy: 3 GeV
I
Current: up to 400 mA
Seven active beamlines
I
I
Laura Torino
+1 Optical beamline for
beam diagnostic
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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C HARACTERISTICS
ψ: Emission angle
ω: Radiation frequency
c: Speed of light
r0 : Classical electron radius
pT : Transverse momentum
γ: Lorentz factor
ωc :
3cγ 3
2ρ
=
εc
~
Fσ , Fπ : Combination of Airy
functions
Observed Power Distribution
2
4πcr0 ṗ2T γ 3
d Pob (ω, ψ)
=
(Fσ (ω, ψ) + Fπ (ω, ψ))
dωdψ
3ωc mc2
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
P OWER D ISTRIBUTION
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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P OWER D ISTRIBUTION
Forward peaked
Lower frequencies @ wide
angles
⇒ Possibility to select the
wavelength
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
B EAM D IAGNOSTIC USING SR
SR characteristics
m
Beam characteristics
Disadvantages
Advantages
I
Produced “for free”
I
Need of a source
I
Wide spectrum
I
Radiation exposure
I
Real-time
I
“Localized”
I
Non-destructive
I
Machine design
Laura Torino
100°Congresso Nazionale SIF
5
ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
B EAM D IAGNOSTIC USING SR
SR characteristics
m
Beam characteristics
Disadvantages
Advantages
I
Produced “for free”
I
Need of a source
I
Wide spectrum
I
Radiation exposure
I
Real-time
I
“Localized”
I
Non-destructive
I
Machine design
X-rays and Visible radiation coming from a bending magnet are
used to measure the transverse beamsize
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
T RANSVERSE B EAM S IZE
Problem
Electron machine ⇒ Beam size ' tens of µm or smaller
m
Diffraction limited using visible radiation
⇓
λ
d = 2n sin
θ ' 100µm
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
T RANSVERSE B EAM S IZE
Problem
Electron machine ⇒ Beam size ' tens of µm or smaller
m
Diffraction limited using visible radiation
⇓
λ
d = 2n sin
θ ' 100µm
Pinhole
Use X-Rays
⇓
Choosing the correct energy
and magnification diffraction
limit is bypassed
Laura Torino
100°Congresso Nazionale SIF
6
ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
T RANSVERSE B EAM S IZE
Problem
Electron machine ⇒ Beam size ' tens of µm or smaller
m
Diffraction limited using visible radiation
⇓
λ
d = 2n sin
θ ' 100µm
Pinhole
Use X-Rays
⇓
Choosing the correct energy
and magnification diffraction
limit is bypassed
Laura Torino
Interferometry
Use Visible radiation
⇓
Measuring the degree of spatial
coherence of the produced
radiation
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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ALBA S.L.S.
PINHOLE
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F UTURE
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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T HE P INHOLE
The Pinhole is a camera
without lenses that works as
a camera obscura exploiting
the natural divergence of the
light.
Used since the 16th century
to study solar eclipses.
σ1 =
Laura Torino
L1
L2 σ2
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
T HE P INHOLE
The Pinhole is a camera
without lenses that works as
a camera obscura exploiting
the natural divergence of the
light.
Used since the 16th century
to study solar eclipses.
σ1 =
Laura Torino
L1
L2 σ2
100°Congresso Nazionale SIF
8
ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
T HE P INHOLE
The Pinhole is a camera
without lenses that works as
a camera obscura exploiting
the natural divergence of the
light.
Used since the 16th century
to study solar eclipses.
σ1 =
I
Laura Torino
L1
L2 σ2
Pinhole
100°Congresso Nazionale SIF
8
ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
T HE P INHOLE
The Pinhole is a camera
without lenses that works as
a camera obscura exploiting
the natural divergence of the
light.
Used since the 16th century
to study solar eclipses.
σ1 =
L1
L2 σ2
I
Pinhole
I
Distances
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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P INHOLE AT ALBA
Copper
To select the
radiation energy
E & 45 keV
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100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
P INHOLE AT ALBA
Magnification
X = LL21
(13626−123) mm
(6059−123) mm =
Laura Torino
100°Congresso Nazionale SIF
2.275
9
ALBA S.L.S.
PINHOLE
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P INHOLE AT ALBA
Beam Size
@ source location
σx = 60 µm and
σy = 28 µm
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
O PTICAL U NCERTANTY
Blurring
Due to the finite size of the
pinhole
Diffraction
Fraunhofer diffraction due to
the long distaces involved
√
w(L1 + L2 )
σB = √
12L1
I
w: Pinhole width
I
λ: Radiation
wavelength
I
σP : CCD pixel size
(' 5 µm)
I
σ1 ' 30 µm
Laura Torino
σD =
s
σobs =
L2
L1
100°Congresso Nazionale SIF
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12 λL2
4π w
!
2 + σ2
σ12 + σB2 + σD
P
10
ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
O PTICAL U NCERTANTY
Blurring
Due to the finite size of the
pinhole
w(L1 + L2 )
σB = √
12L1
I
w: Pinhole width
I
λ: Radiation
wavelength
I
σP : CCD pixel size
(' 5 µm)
I
σ1 ' 30 µm
Laura Torino
Diffraction
Fraunhofer diffraction due to
the long distaces involved
√
σD =
100°Congresso Nazionale SIF
12 λL2
4π w
!
10
ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
O PTICAL U NCERTANTY
Blurring
Due to the finite size of the
pinhole
Diffraction
Fraunhofer diffraction due to
the long distaces involved
√
w(L1 + L2 )
σB = √
12L1
I
w: Pinhole width
I
λ: Radiation
wavelength
I
σP : CCD pixel size
(' 5 µm)
I
σ1 ' 30 µm
Laura Torino
σD =
PSF =
q
12 λL2
4π w
!
2 + σ 2 = 15.10 µm
σB2 + σD
P
v
2
u
u
L2
σ12
u
L1
u
= 97.6%
t 2
L2
2 + PSF2
σ
1
L1
100°Congresso Nazionale SIF
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ALBA S.L.S.
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P INHOLE M EASUREMENTS
On line, stable measure used during operation in the control room
Laura Torino
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ALBA S.L.S.
PINHOLE
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
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T HE SR I NTERFEROMETER
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
T HE SR I NTERFEROMETER
Use the visible part of the
radiation to measure the
beam size
σx = 53.6 µm and
σy = 23.9 µm
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
T HE SR I NTERFEROMETER
Visible light ⇒ Diffraction Limit ⇒ No direct
image
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
T HE SR I NTERFEROMETER
Visible light ⇒ Diffraction Limit ⇒ No direct
image
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
T HE SR I NTERFEROMETER
Visible light ⇒ Diffraction Limit ⇒ No direct
image
(
I = I0
Laura Torino
sinc
2πax
λf
!)2
(
×
1 + V cos
2πDx
!)
λf
100°Congresso Nazionale SIF
σ=
λL
πD
s
1
2
ln
1
V
14
ALBA S.L.S.
PINHOLE
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D IAGNOSTIC B EAMLINE X ANADU
Laura Torino
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ALBA S.L.S.
PINHOLE
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D IAGNOSTIC B EAMLINE X ANADU
Laura Torino
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ALBA S.L.S.
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S ETUP AND R ESULTS
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ALBA S.L.S.
PINHOLE
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F UTURE
S ETUP AND R ESULTS
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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S ETUP AND R ESULTS
Optical components quality is crucial
⇓
Complete upgrade of Xanadu beamline
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
WAVEFRONT E RRORS
In order to obtain good measurements the wavefront error due to
optical components has to be minimize
Fizeau interferometer measurements of the extraction mirror
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
WAVEFRONT E RRORS
In order to obtain good measurements the wavefront error due to
optical components has to be minimize
Fizeau interferometer measurements of the extraction mirror
Old Xanadu Mirror
New Xanadu Mirror
λ
1
Laura Torino
λ
7
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
WAVEFRONT E RRORS
In order to obtain good measurements the wavefront error due to
optical components has to be minimize
Fizeau interferometer measurements of the extraction mirror
Old Xanadu Mirror
New Xanadu Mirror
λ
1
Laura Torino
λ
7
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
WAVEFRONT R ECONSTRUCTION
Problems due to heat load ⇒ needs to check the optical path
condition on-line
Wavefront monitoring using the Hartmann Mask
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
V IBRATION OF THE O PTICAL PATH
I
Floor Vibrations (tens of
Hz)
I
Air Turbulence (up to 300 Hz)
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
V IBRATION OF THE O PTICAL PATH
I
Floor Vibrations (tens of
Hz)
I
Air Turbulence (up to 300 Hz)
I
Laura Torino
CCD exposure time ' tens of
ms
100°Congresso Nazionale SIF
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ALBA S.L.S.
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PINHOLE
F UTURE
V IBRATION OF THE O PTICAL PATH
(
I = I0
I
Floor Vibrations (tens of
Hz)
I
Air Turbulence (up to 300 Hz)
I
Laura Torino
sinc
2πax
λf
!)2
(
×
1 + V cos
2πDx
!)
λf
CCD exposure time ' tens of
ms
100°Congresso Nazionale SIF
19
ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
V IBRATION OF THE O PTICAL PATH
(
I = I0
I
Floor Vibrations (tens of
Hz)
I
Air Turbulence (up to 300 Hz)
I
sinc
2πax
λf
!)2
(
×
1 + V cos
2πDx
!)
λf
CCD exposure time ' tens of
ms
⇒ Attenuating the air
flux
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
Laura Torino
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
W HAT N EXT ?
I
Measurements of vertical beam size
I
Laura Torino
Add the effect of non-monochromaticity to the theory
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
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F UTURE
W HAT N EXT ?
I
Measurements of vertical beam size
I
Use a Fast Gated Camera to perform bunch by bunch
measurements
I
I
Laura Torino
Add the effect of non-monochromaticity to the theory
Study on beam instability at higher current (in
collaboration with CLIC)
100°Congresso Nazionale SIF
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ALBA S.L.S.
PINHOLE
I NTERFEROMETRY
F UTURE
W HAT N EXT ?
I
Measurements of vertical beam size
I
I
Use a Fast Gated Camera to perform bunch by bunch
measurements
I
I
Study on beam instability at higher current (in
collaboration with CLIC)
Scan the slits distance when measuring the horizontal
beam size
I
I
Laura Torino
Add the effect of non-monochromaticity to the theory
Prove study the effect of the Depth of Field
Experimental verification of Mitsuhashi theory
100°Congresso Nazionale SIF
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ALBA S.L.S.
I NTERFEROMETRY
PINHOLE
F UTURE
S UMMARY
Synchrotron radiation is a very
usefull tool for transverse beam
diagnostic (and longitudinal...)
I
Pinhole
I
Interferometry
Not only electrons...
I
I
Acknowledgments
Next LHC run will use
interferometry
Thanks to U. Iriso for the
discussions on the pinhole
Main tool for FCC beam
diagnostic
and T. Mitsuhashi for the
remarkable help with the
interferometer
This project is funded by the European Union under contract PITN-GA-2011-289485
Laura Torino
100°Congresso Nazionale SIF
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BACKUP SLIDES
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100°Congresso Nazionale SIF
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U NCERTANTY ON THE S OURCE P OINT
Depth of field
Orbit Position
I
αH = ±0.49 mrad
I
∆xH = ±2.330 mm
I
ρ = 7.03 mrad
I
∆xY = 15 mm
∆sH = ±3.52mm
∆sO = ±4.16mm
∆s = ∆sH + ∆sO = ±7.68 mm
Laura Torino
100°Congresso Nazionale SIF
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U NCERTANTY ON THE S OURCE P OINT
∆βx ' 0.017 m
∆βx ' 0.010 m
⇓
∆εx ' 0.3 nm
∆εy ' 0.01 nm
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F IEZAU I NTERFEROMETER
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