1. Start to end design of a dedicated laser driven proton hybrid beamline for Cultural heritage applications
Antonia Morabito
15 October 2018

2. Proton Induced X-ray emission (PIXE) in cultural heritage (CH)
Innovative physical and chemical technique for Cultural Heritage for both diagnostic and conservations.
Proton beams (1-4 MeV) hit the target
Core electronic excitation
X-ray produced from subsequence electron hole or vacancy rearrangement
Produced radiation measured by an energy-dispersive detection system
a characteristic fingerprint of each chemical element present in bulk sample.

3. Diagnostic: PIXE with conventional accelerator
‘’Accélérateur Grand Louvre d'analyse élémentaire’’(AGLAE)-
CENBG – Bordeaux - INFN LABEC – Florence (Italy)
Drawbacks
Large facility
Limited energy tunability (1-3 MeV)
Penetration depth 20 µm below the surface
surface decoration or corrosive patina
Highly localised analysis
beam sizes are generally in the order of µm2
Stepwise measurement
Long analysis time
each point s measuring time
High adsorbed dose (potential damage)

4. Alternative: laser-accelerated protons for PIXE analysis
Typical TNSA JLF-TITAN
Target Normal Sheath Acceleration (TNSA)
Intensity ~ 1020 W/cm2
Laser energy ~ up to 220 J
Focal spot diameter (FWHM) ~ 9 µm
Pulse duration ~ 700 fs
Central Wavelength ~ µm
Repetition rate << 1 Hz
Laser Intensity on target typically →>1018 W/cm2
Laser energy →few Joules to ten of Joules
Pulse duration of tens of fs, up to ps
Target thickness from several µm to tens of nm.
Advantages of PIXE with laser-driven proton beams:
higher charge for each shot
higher signal-to-noise ratio allows shorter measuring times
larger analyzed surface due to larger beam spot-size
layer-by-layer analysis by energy tuning

5. LDPA as Diagnostics for CH applications
‘’One-shot’’ PIXE Experimental setup
Energy range X-ray spectrometer KeV
Experimental goals:
Damage investigation: direct irradiation of a ceramics artefact (6 cm distance from the source)
PIXE spectroscopy: direct irradiation of a known material sample and X-ray spectrum analysis
Marianna Barberio, Simona Veltri, Massimiliano Sciscio, and Patrizio Antici. Laser-Accelerated Proton Beams as Diagnostics for Cultural Heritage. Scientific Report,  (2017) 7: 40415;
DOI: /srep40415

6. Results: LDPA – diagnostic for CH heritage
Ancient Ceramic from the medieval archeological situ of Nicastro
Provider: Sovraintendenza ai beni culturali Regione Calabria
No aesthetic damage after irradiation
No chemical composition change of the irradiated sample
Marianna Barberio, Simona Veltri, Massimiliano Sciscio, and Patrizio Antici. Laser-Accelerated Proton Beams as Diagnostics for Cultural Heritage. Scientific Report,  (2017) 7: 40415; DOI: /srep40415

7. Results: LDPA as diagnostic for CH heritage
Bragg’s law
IP image with one shot!
Ag sample
6 cm
Ag Lα
Ag kα (22 KeV)
Ti Kβ
Cr Kβ
2.54 cm
Silver sample position
The one shot PIXE data are in agreement with conventional XRF data on the same sample

8. PIXE : Conventional accelerators vs LDPA
Starting point: Proof of principle experiment of ‘’laser-driven PIXE’’
Advantages:
Potential lower damage for artifacts (analysis of the ceramic artifact)
Complete chemical analysis of the silver sample in ‘’one single’’ laser-driven PIXE
Disadvantages :
Protons are accelerated within a cone of tens of degrees
Initial energy spread for the layer by layer PIXE analysis.
Study and design of a dedicated transport beam line for the LD Proton Beams for CH applications

9. Proposed hybrid beamline for PIXE : Energy selector (ES) + quadrupole (QUAD)
50 cm /90 cm
ES is a magnetic chicane of 2/4 permanent magnets
~ 23.5 cm
Design and optimization by PhD thesis of Dr. Scisciò
The quadrupole/s (QUAD) coupled with the ES.
Compact version: 50 cm
Extended version : 90 cm

10. TSTEP and TRACE3D simulations for PIXE hybrid beamline
Different set of TSTEP and TRACE3D simulations were perfomed:
Test Energy selection performance in the range typical of PIXE (1-3-5MeV)
The energy selector gives:
the possibility to tune the proton beam in the low range needed for PIXE (‘’layer by layer analysis’’)
Obtain a quasi-monoenergetic beam
Limit chromaticity effect
Study the coupling of the ES + quadrupole/s (QUAD)
Test the advantage to focus and shape the final spot sizes according to the artifact analyzed.
Verify the feasibility of the quadrupole addition, varying its position between the ES and the sample.

11. TSTEP simulations for test the energy selector performance
Input : initial uniform distribution
The quadruple addition does not change the final energy spread.
Case 1 MeV
Case 5 MeV
Case 3 MeV
a.u
a.u
Final energy spread: 14%
Efficiency: 9%
Final energy spread: 10%
Efficiency:12%
Final energy spread: 11%
Efficiency:9%

12. Compact hybrid beamline:Test feasibility of the quadrupole addition
Case : 1MeV
Smaller spotsize (y)
Bigger spotsize (y)
Proton source ES
7.35 cm
3.15cm
Proton source
8.25cm ES
2 cm
Final spot size: 3.4 mm x 0.44 mm;
Final spot size: 4.9 mm x 10 mm;

13. Compact hybrid beamline:Test feasibility of the quadrupole addition
Case : 3 MeV
Smaller spotsize
Bigger spotsize
Proton source ES
3 cm
7.5cm
Proton source ES
10 cm
0.5 cm
Final spot size: 2.4 mm x 0.36 mm;
Final spot size: 1.5 mm x 9.2 mm;

14. Normal hybrid beamline:Test feasibility of the quadrupole addition
Case : 1MeV
Smaller spotsize
Bigger spotsize
Proton source
31.05 cm ES
4.457 cm
Proton source ES
24.39 cm
11.11 cm
Final spot size: 8.9 mm x 0.67 mm;
Final spot size: ; 11 mm x 17 mm;

15. Normal hybrid beamline:Test feasibility of the quadrupole addition
Case : 3 MeV
Smaller spotsize
Bigger spotsize
Proton source
25.68 cm
9.81 cm
Proton source ES ES
18.67 cm
16.82 cm
Final spot size:5.5 mm x 8.9 mm;
Final spot size: 4.8 mm x 0.53 mm

16. Focusing/defocusing quadrupoles
Proposed hybrid beamline for PIXE : ES + 2 quadrupoles
Focusing/defocusing quadrupoles
X-ray emission
Energy selector + 2 quadrupoles
Compact distance: 50 cm
X-ray detector

17. Compact hybrid beamline:Test feasibility of the quadrupole addition
Case : 3 MeV
Proton source ES
1 cm
1.5 cm
3.5 cm
Final energy spread: 11%; Overall efficiency: 9%.
Final spot size: 1 mm x 1 mm; 3mmx3x3mm

18. Conclusions and future plan
The proposed hybrid beamline :
Successfully reduces the initial energy spread at the source to 10%-20% (‘potential ’layer by layer’’ PIXE)
Addition of a quadruple/s give tunability in final transverse spotsizes on the sample according to studied artifact.
Quadrupole parameters: 80 T/m, bore radius: 1 m, length: 4.5 cm (compact version). a lower gradient is possible for an extended distance.
Comparable with the Classical PIXE using a 10Hz intense laser system
Future plans…
Test the feasibility of ‘’laser–driven PIXE’’ with different types of CH materials such as : marbles, silicates, noble metals, pigments etc..
Perform laser-driven PIXE using a lower power laser i.e., a lower proton flux
Finalize and further improve the hybrid beam line design with an additional initial focusing stage
Investigate the possibility of ‘’laser-driven PIXE’’ both in vacuum and in the air.

19. Thank you for your attention!