Profile Measurements with Scintillators: Requirements and Applications at Accelerators Gero Kube DESY (Hamburg) Introduction Profile Measurements with Scintillators Stability and Resolution Summary and Outlook Joint ARIES-ADA Workshop on ‘Scintillation Screens and Optical Technology for transverse Profile Measurements‘ Krakow, April 1 - 3, 2019
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Profile Measurements with Scintillators:
Requirements and Applications at
Accelerators
Gero KubeDESY (Hamburg)
Introduction
Profile Measurements with Scintillators
Stability and Resolution
Summary and Outlook
Joint ARIES-ADA Workshop on ‘Scintillation Screens and
Optical Technology for transverse Profile Measurements‘
Krakow, April 1 - 3, 2019
Gero Kube, DESY / MDI
Introduction
historical screen monitor
ARIES Workshop, Krakow, April 1-3, 2019
Geiger–Marsden experiments
(Rutherford gold foil experiment)
→ series of experiments: 1908 – 1913
atom contains nucleus where all positive
charge and most of mass is concentrated
H. Geiger, E. Marsden, Philosophical Magazine 25 (1913) 604.
setup of 1913 experiment
→ particle beam (α particles)
→ viewing optics (photon counting)
→ moveable screen (ZnS) B. Walasek-Höhne and G. Kube,
Proc. DIPAC‘11, Hamburg
(Germany), p.553
present screen monitor for beam diagnostics
particle beam → e±, p, heavy ions, (γ)…
optics (+ detector) → imaging
scintillating screen main goal of this workshop
(with cameras & optics)
Gero Kube, DESY / MDI
Scintillators for Beam Diagnostics
workshop on ‘Scintillating Screen Applications in Beam Diagnostics’
ARIES Workshop, Krakow, April 1-3, 2019
bring together experts from different fields
B. Walasek-Höhne et al., IEEE Trans. Nucl. Sci. 59 (2012) 2307.
sufficient efficiency in energy conversion into light
large dynamic range
emission spectra matched to spectral response of photon detector
good linearity between incident particle flux and light output
good spatial resolution
short decay time for reduction of saturation effects
good mechanical and thermal stability
high radiation hardness to prevent material damages
properties of good scintillator
GSI Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany)
February 14-15, 2011
→ https://www-bd.gsi.de/ssabd/
intensity
reproducibility / resolution
stability
properties affected by
scintillator material
beam
light emission from channel
isotropic emission
light has to cross boundary
between scintillator / vacuum
Gero Kube, DESY / MDI
Beam Image Generation
particle crosses scintillator
ARIES Workshop, Krakow, April 1-3, 2019
formation of ionization
channel
imaging with lens onto detector
image of channel
→ diameter O(nm)
superposition of channel images
beam image generation
Gero Kube, DESY / MDI
Scintillation Light Generation
multi-stage process
A.N. Vasil‘ev, Proc. SCINT’99,
Moscow (Russia), 1999, p.43
energy conversion → generation of “hot” electronic excitations
thermalization → phonon emission: transform Tkin of excitations in heat
localization → excitation interaction with defects/impurities
transfer to luminescent centers → migration of relaxed excitons
radiative relaxation → emission of scintillation light
ARIES Workshop, Krakow, April 1-3, 2019
scintillator
material
particles
(mainly)
Gero Kube, DESY / MDI
Stage 1: Beam
ARIES Workshop, Krakow, April 1-3, 2019
charged particle interaction with target material (scintillator)
inelastic scattering (impact ionization)
fundamental difference between light / heavy particles
“heavy” particles: A ≥ 1 → p, α, ions,…
“light” particles → e±
𝑀, 𝑣𝑝 𝑚𝑒 , 𝑣𝑒 = 0
𝑀, ƴ𝑣𝑝
𝑚𝑒 , ƴ𝑣𝑒
∆𝐸𝑚𝑎𝑥
𝑇𝑘𝑖𝑛= 4
𝑚𝑒𝑀
𝑚𝑒 +𝑀 2
energy transfer from beam particle to scintillator shell electron