Multi-colour sctintillator-based ion beam profiler
James Green, Oliver Ettlinger, David Neely(CLF / STFC)
2nd Ion diagnostic workshopJune 7-8th
Talk outline
• Diagnostic outline
• Multi-channel characterisation
• Reducing EMP & radiation effects
• Demonstration on Astra Gemini
• Future developments
High-repetition rate advances
• Passive media (CR-39, RCF, Image plate) increasing unsuitable
• Transition to active diagnostics:Scintillators, Micro-channel plates (MCPs), Phosphor screens
Target
LaserCCD
Fibre bundle
Scintillators
Lens
Ion beam
Micro-channel plates (MCP)
Radiochromic film (RCF)
2D detector head development
• Diagnostic aims:– 2D beam profiling– Spectral measurement– Beam pointing– Calorimetry
• Compact scintillator beam head– Scintillator thickness determines
energy observation window– Each scintillator has a separate
central emission wavelength– Need to avoid optical excitation
within scintillator stackSc
intil
lato
r 3 (B
lue)
Scin
tilla
tor 1
(Ora
nge
Scin
tilla
tor 2
(Gre
en)
Incident Protons
100 mm 90 mm
Detector head
Proton stopping ranges
Optical Stimulation
• Optical Stimulation:– Emission from Blue or Green scintillators can optically
stimulate emission from scintillators earlier in the stack
– How to stop light travelling back through the system?
5
Scin
tilla
tor 3
(Blu
e)
Scin
tilla
tor 1
(Ora
nge
Scin
tilla
tor 2
(Gre
en)
Incident Protons
Reducing EMP / radiation impact
• High resolution 800 x 800 fibre bundles– Image relay from Phosphor / Scintillator to camera
outside interaction chamber– Durable with flexible deployment options– Wide transmission range– Long fibre lengths (> 5 m) possible
• Eliminating background radiation– Gated CCDs to block X-ray / electron signal– CCD safely shielded from hard hits
60um
60um
Core
OpticalCladding
OpticalCore
Groups of fibres inside bundle
Channel separation
• Signal split in front of camera into 4 channels, RGB + Extra
• Dichroic filters used to isolate each scintillator signal
RedGreen
Blue All channelsData obtained using from SRIM – http://www.SRIM.org
Data Deconvolution
• System characterised using a Cyclotron proton source
• Produced a response matrix for each colour channel
8
Predicted Response Matrix - Ideally require 1 on the diagonal,
with 0 everywhere else
Astra Gemini experiment• Astra Gemini –
– 12J 50fs– 5x1020 Wcm-2
– >1010 contrast– TCC – Scintillator = 20 cm Sc
intil
lato
r 3 (B
lue)
Scin
tilla
tor 1
(Ora
nge
Scin
tilla
tor 2
(Gre
en)
Incident Protons
1 - 4.5 MeV7-9 MeV
10.5 - 14 MeV
Laser
Astra Gemini experiment
1- 4.5 MeV 7-9 MeV 10.5-14 MeV
0 100 200 300 400 500 600 700 800 900 10000
20
40
60
80
100
120
Target thickness (nm)
Mea
n CC
D co
unts
50 nm Al
• Shot a range of Al foils, 25-900 nm• Clear signals on orange and green
channels, insufficient flux for blue• Clear structure visible with peak off
axis for some shots
FOV = 30o
100 nm Al
Imaging novel targetry
• Microspoke targets shot on Astra Gemini
• Proton beam imaged using RCF and Scintillator stack
11
1mm
Disks: 32um diameter, 40nm thick SiN membranes
Supporting wires: 1µm wide , 40 nm thick
Hole etched through 400μm thick Si.
Scintillator
RCF
10 Hz operation
• Scintillator considerations:– Rapid (s) recovery between shots– Minimising high dose damage
• Implement new Scientific CMOS camera– 30 fps continuous full-frame operation– Low noise read-out, 16-bit Dynamic range
• Data analysis– Real-time data deconvolution for live beam
profiles (Desirable – looking for collaborators?)
Future developments
• Further diagnostic testing– 0.05 Hz to 10 Hz progression– Efficient data capture and analysis
• Scintillator development– Thin scintillators for high spectral resolution– Calibration at higher (> 30 MeV energies)– Faster scintillators for fast gating– Media lifetime
• Experimental & industrial collaborations– Experimental access on range of facilities– Next-gen imaging and scintillator technology