The LIBRA project: progress in source development and radiobiology applications

M.Borghesi

The Queen’s University of Belfast

Centre for Plasma Physics, School of Mathematics and Physics

Meeting on Laser-Plasma accelerators, Imperial College, 13 December 2012

Contributors

S. Kar, D. Doria, R. Prasad, K.F. Kakolee, K. Quinn, B. Ramakrishna, G. Sarri, B. Qiao,

M.Geissler, M. Zepf, Centre for Plasma Physics, Queen’s University Belfast,

J.Kavanagh, G. Schettino, K. Prise,

Centre for Cancer Research and Radiation Biology, Queen’s University Belfast

D. Neely, D. Carroll, J. Green STFC-Rutherford Appleton Laboratory,

P .McKenna, X. Yuan, University of Strathclyde,

Z.Najmudin, N.Dover, C. Palmer, J Schreiber Imperial College,

F. Fiorini, D.Kirby, S. Green, University of Birmingham,

M. Merchant, C.J.Jeynes, K.Kirkby, University of Surrey,

M. Cherchez, J. Osterholtz, O. Willi, Heinrich Heine University Dusseldorf,

A. Macchi, University of Pisa

Laser Induced Beams of Radiation and their Applications

Basic Technology programme, 2007-2012

Collaboration

LIBRA

STFC

NPL

Project aimed to develop target, detector and interaction technology required for high repetition, high energy operation of radiation sources.

Outline

• Current properties of laser-ion beams

• Proposed applications/requirements • Current research applications:

• Radiobiology

• Future applications: cancer therapy

• Prospects for energy increase• Radiation Pressure Acceleration

VULCANEnergy : up to 500 J (on target)Wavelength : 1.05 mPulse duration : 0.5 ps Intensity : ~1-5 1020 Wcm-2 Repetition : 8 to 10 shots / day

Petawatt-class laser systems at the CLF, RAL

GEMINI Laser, CLF, RAL: E ~ 12 J , = 0.8 µm, = 50 fsFocal spot : 5 µm FWHM Intensity~ 1021 W/cm2

Rep rate : 1- 10 second

Sheath acceleration: ion beam properties

• Low emittance: rms emittance < 0.01 mm-mrad • Short duration source: ~ 1 ps (Et < 10-6 eV-s) • High brightness: 1011 –1013 protons/ions in a single shot (> 3 MeV)• High current (if stripped of electrons): kA range

• Divergent (~ 10s degrees)• Broad spectrum• Maximum energies: ~ 70 MeV

• Scaling: E ~ (Il2) 0.5

Ion beam from TARANIS facility, QUB

E ~10 J on target in 10 µm spot

Intensity: ~1019 W/cm2, duration : 500 fs

Target: Al foil 10um thickness

Prospective applications of laser-driven ion acceleration

Radiography (density measurements)

Deflectometry (field measurements)

Isochoric heating of matter

Neutron production

Material studies (Irradiation)

Radiobiology

Cancer therapy

Production of isotopes for PET

Fusion Energy (Fast Ignition)

Nuclear/particle physics applications

150-250 MeVprotonsCarbon ions at 2-4 GeV

Energies >GeV(high repetition)

Applications already activewith TNSA beams

What would ion beam users require ?

• Wide energy and fluence range ✔• Different ion species ✔• Homogeneous transverse beam distribution ✔• Stability in terms of energy/fluence distribution• Variable beam spot size• Beam control (diagnostic/dosimetry) within 5% error• High repetition

Beamline approach (ELIMED beamline, Prague)

Unique to laser-driven beams:Ultrashort particle burst duration (ps at sources)Ultrahigh dose rate (> 109 Gy/s)

Charged particle therapy of cancer

Ballistic advantages

Biological advantages

Ions permit precise targeting of the tumor,minimizing the dose deposition in healthy tissues

Large number of direct DNA damage. More effective in destroying radioresistant tumours (particularly with Carbon)

Compared to conventional x-ray radiotherapy:

Hadrontherapy centres worldwide are limited in number

• 8 in the USA• 6 in Japan• 12 in Europe/Russia• 3 in China, Korea, South Africa• 1 in UK ( Clatterbridge, limited to 60 MeV)

Only 3 facilities use Carbon ions

2 protontherapy trial centres currently being developed in the UK(active by 2017, UCLH London, Christie Hospital Manchester).

There is need for developing alternative approaches to hadrontherapy which may in future, help the treatment becoming more widespread / more efficient.

Very high cost: >£ 100 M for protons, >£ 250 M for proton+CarbonSignificant fraction of costs: transport/delivery systems (up to 50-70%)

Reduced cost/shielding/size: • possibility to avoid/reduce size of gantry• laser transport rather than ion transport (vast reduction in radiation shielded space)

Flexibility:• Possibility of controlling output energy and

spectrum• Possibility of varying accelerated species(H, C , but also intermediate species)

Novel therapeutic/diagnostic optionsMixed fields: x-ray + ions , multiple beamsIn-situ diagnosis

High dose rates effects

Laser-driven ions: a source for future radiotherapy?

Several projects worldwide:

SAPHIR (France)FDZ Dresden/ MPQ (Germany)ELIMED (Cz)Fox Chase Centre (USA)

• Compared to conventional accelerators what do we need to improve?

- Narrow angular distribution– Narrow energy distribution

(not simply slicing)– Beam purity– High repetition, stability– Higher endpoint energy

Radiobiology experiments

We carried out tests of biological effectiveness oflaser-driven ions on V79 cells by using the TARANIS laser at QUB

Main aims:• establish a protocol for proton irradiation

compatible with a laser-plasma environment• establish a procedure for on-shot dosimetry• Demonstrate dose-dependent cell damageon single exposure, high dose irradiations• test for any deviation from known results using

conventional sources

Previous work :S. Yogo et al, APL, 98, 053701 (2011)S.D. Kraft et al, NJP, 12, 085003 (2010)

Chinese hamster(Cricetulus griseus) TARANIS proton spectrum

Dose of ~ 1-10 Gy is delivered in several fractionsEach fraction has a short duration – 10 nsBut effective dose rate ~ Gy/s – Gy/min

Dispersion: in 20mm from 3MeV to 10MeV

Energy Res.: ~ 2 MeV energy overlapping (500um slit)

Delivered dose @ 1-5MeV: ~ few Gy/shot

Proton beam characteristics at cell plane

50 um Mylar window

Focusing Parabola

Laser Beam Slit (500 µm)Target

0.9 T magnet

SN

Setup for cell irradiation

Vacuum chamber Wall

D

Mylar window : 50 µm

1 cm

D ~ 27 cm

1 cm

Cell Irradiation Protocol for clonogenic assay

Energy

Shadows of the cell dots

Chinese Hamster Cell culture Sample preparation

Cell IrradiationPost-irradiation processingColony formation

Single shot survival curve!

Cell damage investigated at ultrahigh dose rates (> 109 Gy/s)

RBE10 estimated at ~1.4In line with “standard” results with V79 cellse.g. Folkard et al, (1996) – Same RBE with LET=17.8 Kev/µm

SF comparable with literature data at similar dose and energy but longer pulses

Higher dose/dose rates obtainable with beam colllimation, or low dispersionmagnetic systems

D.Doria et al, AIP Advances 2, 011209 (2012)

Future tests: DNA damage, higher LET ions,Effects of oxygen depletion

Enhanced options offered by access to CLF lasers (GEMINI experiment scheduled in summer 2013)

High efficiency producton of H and C beams from ultrathin foils (e.g. 25 nm at 5 1020 W/cm2)

• Radiation pressure acceleration• Hole boring • Relativistic transparency/

Break out afterburner C.A. Palmer et al, Phys. Rev. Lett, 106, 014801 (2011)

D. Haberberger et al, Nat Phys, 8.95 (2012)

A. Henig, et al, Phys. Rev. Lett. 103, 045002 (2009)

D. Jung et al, Phys. Rev. Lett.,107, 115002 (2011)

Shock acceleration

Radiation pressure acceleration Light Sail

Ion energy increase: several emerging mechanisms are being explored (besides TNSA optimization)

Radiation Pressure on thin foils - light sail

• Cyclical re-acceleration of ions • Narrow-band spectrum (whole-foil acceleration) • Fast scaling with intensity

e-Z+

€

FR = (1+ R)A IL

c

€

⇒ v i =(1+ R)τminid

IL

c∝ Iτη −1

η = minid Areal density

Issues at present intensities• Competition with TNSA• Hot electron heating cause foil disassembly(ultrathin foils are needed for moderate a0)

€

W ~ IL τ η( )2

T.Esirkepov, et al. Phys. Rev. Lett., 92, 175003 (2004)O.Klimo et al, Phys. Rev. ST, 11, 031301 (2008)APL Robinson et al, NJP, 10, 013021 (2009)A.Macchi, S. Veghini, F. Pegoraro, Phys. Rev. Lett. , 103, 085003 (2009)

Scaling decreases for relativistic ions : linear scaling with I for vi~ c

PIC investigations of Radiation Pressure Acceleration(Light Sail regime)

B. Qiao et al, Phys Rev Lett,102,145002 (2009)

Generally unstable at lower intensities, but:2-species targets lead to stabilized acceleration of lighter species already at ~1020 W/cm2.

B. Qiao et al, Phys Rev. Lett., 105, 1555002 (2010)B.Qiao, et al, Phys. Plasmas, (2011)

2D PIC ILLUMINATION code

Condition for stability of Light Sail identified (smooth transition between hole boring and light-sail phase,GeV protons at > 1022 W/cm2)

LIBRA campaigns at the CLF, RAL

VULCAN Petawatt

Pulse duration ~ 750 fs

Energy on target up to 200 J

Intensity up to 3 x 1020 W/cm2

Scans made by varying :• Laser Intensity, polarisation• Target density, thickness

Typical feature from ultrathin foils: Co-moving ions of diff e/m

100nm Cu; Linear Pol; I = 3 x 1020 W/cm2

Solid line: TP1 (laser axis)Dotted line: TP2 (13o off axis)

1 1010000000000

100000000000

1000000000000

10000000000000

Energy/nucleon (MeV)dN

/dE

(in /

MeV

/Sr)

50nm Cu; Cirular Pol; I = 1.5 x 1020 W/cm2

e/m = 1e/m = 0.5e/m = 0.42

Hybrid regime where RPA cohexists with TNSA

No significant dependence on polarization

2D PIC, multilayer, multispeciesDensity profile at two different times

Cu

C

p

S. Kar et al, Phys. Rev. Lett, 109, 185006 (2012)

Scaling of carbon peak with Light sail parameter

€

a02 dt η( )

2

Energy of peak scales ~

€

I τ η( )2

Henig, PRL (2009)

S. Kar et al, Phys. Rev. Lett, 109, 185006 (2012)

€

I τ η( )

€

I τ η( )2

Conversion efficiency into peak ~ 1%

Scaling highly promising for achieving high Ion energies

101 102 103 104100

101

102

103

a02tp/c

Ion

ener

gy (

MeV

/nuc

leon

) Eion (a02tp/c)2

Incr

ease

Flu

ence

, or,

Dec

reas

e c

Red dots: 2D and 3D results from multispecies simulations of stable RPA taken from literature

Inset : PIC simulation scaled up from VULCAN data (2 X I, 1/2.5 target areal density)

45 fs @ 5x1020 W/cm2

450 fs @ 5x1019 W/cm2

€

I τ η( )

Similar spectra and scaling in GEMINI results – (Similar intensities but shorter pulses)

GEMINI data : Laser parameters : 50 fs, 6 J , 1-5 10 20 W/cm2

Targets : Carbon (amorphous), density: 2g/cc, thickness: 10-100 nm

Only lightest species shows peaks – not bulk componentOnset of target transparency for the thinnest targets?

C - 25 nm

PIC syms

Conclusions

Some of present applications of laser-driven ions exploit unique and distinctive

properties of laser-ion beams (short duration, low emittance, small source):

proton radiography/deflectometry, Warm dense matter studies

Real time material damage studies, Ultra-high dose rate radiobiology

Applications currently covered by conventional accelerators (e.g. cancer therapy)

require a marked improvement of parameters for laser-drivers to be competitive:

Compactness Is a clear advantage, but improvements are required in terms of energy,

flux, etc.., but also high-average power, towards a beamline approach.

Radiation Pressure Acceleration is emerging from experiments, and promising for

future delivery of pulses at high flux and high energies (medical energies and beyond)

The LIBRA project: progress in source development and radiobiology applications

X-Rays Protons

Orbital Rhabdomyosarcoma

Courtesy T. Yock, N. Tarbell, J. Adams

ILLUMINATION 2D PIC code (M. Geissler)

• Stable acceleration requires smooth transitionbetween “hole boring” phase and LS phase

RP in phase 1: 2I/c Χ (1-vb/c)/(1+vb/c) RP in phase 2: 2I/c Χ (1-vi/c)/(1+vi/c)

• Need to drive target quite “hard” to achieve a highhole-boring velocity (vb~c) before transition

B. Qiao et al, Phys Rev Lett,102,145002 (2009)

Radiation pressure acceleration in the light sail mode: GeV energies at 1022 W/cm2

30 nc

Unstable case

ILLUMINATION PIC code (M. Geissler, QUB)

Unstable caseA.P.L. Robinson et al, NJP (2009)

Rayleigh TaylorinstabilityF. Pegoraro, S.V. BulanovPRL (2007)

100 nc

5 1022 W/cm2

In multi-species targets the acceleration of the lighter species is inherently more stable

• Target: electron density ne0=200nc, thickness l0=8nm<ls C6+ and H+ : nic0=32.65 nc, nip0=4.1nc with nic0:nip0=8:1

I0 ~ 51019W/cm2, 40 laser cycles, l= 1 µm

the proton layer moves ahead of the C6+ layer.

Debunching of the electron layer - complete separation of the C6+ and proton layers. Strong electron leakage

Electrons

H+

C6+

B. Qiao et al, Phys Rev Lett , 105, 1555002 (2010)

The C6+ layer has insufficient charge-balancing electrons- Coulomb explosion

Proton layer is surrounded by an excess number of electrons--->Stable RPA!!