scintillator-based online detectors for laser-accelerated protons – concepts and realizations
DESCRIPTION
Scintillator-based online detectors for laser-accelerated protons – Concepts and realizations at the DRACO lab. J. Metzkes, K. Zeil, S.D. Kraft, N. Stiller, U. Schramm, L. Karsch, C. Richter, J. Pawelke, M. Sobiella - PowerPoint PPT PresentationTRANSCRIPT
Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Scintillator-based online detectors for laser-accelerated protons
–Concepts and realizations
at the DRACO lab
J. Metzkes, K. Zeil, S.D. Kraft, N. Stiller, U. Schramm, L. Karsch, C. Richter,
J. Pawelke, M. Sobiella
Instrumentation for Diagnostics and Control of Laser-Accelerated Proton
(Ion) Beams II
June 7 – 8, 2012
Seite 2 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
The DRACO laser facility
time [fs]
30 fs
-80 -40 0 40 80
Ti:SapphireCPA laserrep rate: 10 Hz2-3 J (on target)I ~1021 W/cm2
ns-ASE contrast 10-10
*Dre
sden
lase
r acc
eler
atio
n so
urce
Seite 3 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Proton acceleration at DRACORCF @ wheel2Doffline
target changer
targetmanipulation
Thomson parabolasmall solid angleonline
online laser parameter control
Seite 4 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Proton acceleration at DRACORCF @ wheel2Doffline
target changer
targetmanipulation
Thomson parabolasmall solid angleonline
online laser parameter control
Status stable high repetition rate laser system reliable proton source high degree of remote control under vacuum
online optimization and monitoring of acceleration performanceapplication experiments
online spectrometers for protons & ions (1D or 2D)
NEE
D
Seite 5 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Why plastic scintillators?
Mainly practical reasons: easy to handle available in nearly any size and thickness no support necessary immediate light emission after excitation online information variable emission wavelength in the visible range signal readout with CCD cameras less EMP issues fast decay rates possible TOF applications linear response to particle flux
light emission saturates with dE/dx calibrationlight emission degrades with total dose exposition
Seite 6 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Detector setup1D angularly resolved online spectrometer for protons
•scintillator stack: 10 layers of BC 418 (Saint-Gobain crystals), maximum emission @ 391 nm
•resolution of 10 proton energy ranges
•light guide principle slim scintillator unit (15 mm x 76 mm)
•fan-like setup for good spatial resolution
•detection area: 10 mm x 50 mm detection angle as for RCF (~ 26° half angle )
• compact detector: scintillator and camera unit only 300 mm x 80 mm
•radiation shielding with Pb
Seite 7 Mitglied der Helmholtz-GemeinschaftJosefine Metzkes [email protected] www.hzdr.de HZDR
Detector setup
camera:
◦ 16 bit camera high dynamic range
◦ 1600 x 1200 px chip size, 4.4 µm pixel size
camera unit directly coupled to the scintillator:
◦ light tight connection stray light suppression
◦ high light yield
◦ good spatial resolution 7px per layer thickness
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Imaging properties
edges roughened to avoid reflection
imaging edge polished
spatial resolution
surfaces polished for efficient reflection
182 mm
8.6 mm
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Detector setup & proof of principle
proton distribution reconstructed from RCFp+
ener
gy
Measured proton distribution
CCD camera image
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Detector setup & proof of principle
p+
ener
gy
Measured proton distribution
CCD camera image
sufficient signal-to-noise ratio (>2) for signal detection shielding against electron and x-ray background maximum proton energy and yield online accessible for the full divergence angle of the proton beam online detection of beam inhomogeneities improves online beam optimization
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Detector characterization @ Tandetron6 MV tandetron at the HZDR Ion Beam Center
12 MeV p+ beam
FC – 25.4 mm diam. detection surface current ~ 100pA
detector
reference RCF – beam homogeneity
beam defining aperture – 10 mm diam.
reference RCF – beam position
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Sensitivity calibration
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Sensitivity calibration
dE/dx saturation of scintillator light output
light transport within the scintillator case correction possible
condition of polished scintillator edge
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Lateral homogeneity
lateral position
decrease due to imaging properties
• overall lateral homogeneity: ~ 80%
• inhomogeneity due to scintillator conditions stable measured curves give correction factors
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Imaging properties testing
spatial resolution imaging properties
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Imaging properties testing
spatial resolution imaging properties
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Detector application
Idocisap
erture
beam fil
ter
apert
ure
targetlas
er
onlin
e de
tect
or
proton beam
Phys. Med. Biol. 56 (2011) 1529–1543
non-invasive online access to spectral distribution and yield of accelerated protons
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Detector application
optimal focus 25 µm out of focus
dispersion
ener
gy
online optimization & monitoring of experimental performance via maximum proton energy & yield
shot-to-shot monitoring via yield (higher sensitivity)
online spectral monitoring dosimetry
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2D online detector development
profile A-A`
profile B-B`
profile C-C`
2,5
0,4
0,7
1,0
1,9
2,1
2,5
1,2
1,4
1,6
Idea: mimic an RCF stack 2D spectrum ONLINE
~ 50
~ 50
4,5
4,5
A A`
B B`
C C`
Schnitt A-A`
Schnitt B-B`
Schnitt C-C`
2,5
0,4
0,7
1,0
1,9
2,1
2,5
1,2
1,4
1,6
CCD camera
scin
tilla
tor
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2D online detector development
~ 50
~ 50
4,5
4,5
A A`
B B`
C C`
cam
era
unit
absorber matrix & scintillator (BC 416, thickness 260 µm)
Detector setup
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2D detector testing
test with 12 MeV p+
basic pixel (9 energies): 4.5 x 4.5 mm 121 pixels on a 50 x 50 mm plate
diam 1.5 mmdist 2.0 mm diam 1.5 mm
dist 2.25 mm
diam 1.5 mmdist 2.50 mm
diam 1.5 mmdist 2.75 mm
diam 1.0 mmdist 1.50 mm
Test matrix optimized for tandetronexperiment (12 MeV protons)
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2D detector testing
basic pixel (9 energies): 4.5 x 4.5 mm 121 pixels on a 50 x 50 mm plate
Progress final design for basic pixel sensitivity calibration @ tandetron test of p+ scattering in angled holes
To do
• test of a final design @ DRACO
performance with background radiation
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(multiple filamentation of a freely propagating 100 TW beam in air)
… thanks for your attention