Carpathian Summer School, Sinaia, Romania 2012
Ken Ledingham
SUPA, Dept of Physics, University of Strathclyde, Glasgow G4
0NG, Scotland & AWE plc Aldermaston, Reading, RG7 4PR,

Over the last 10 years my group and now the SUPA group working with Klaus
Spohr have worked on what we call “Laser Induced Nuclear
Physics”-
What is this?

What are the Laser Driven
Nuclear Reactions?
•
Gamma induced fission
•
Gamma and proton cross sections
•
Laser produced neutron activation analysis
•
Photon and charged particle production of radio-active isotopes including PET isotopes
•
Laser production of monoenergetic protons

VULCAN petawatt laser (RAL)
Energy 600 J (on target)
Repetition 1 hour
Wavelength 1.05
 m
Pulse duration 0.6 ps
Intensity ~6x10 20 Wcm -2
Maximum pulses per week ~25

Petawatt with Extensive Nuclear
Shielding

Nuclear beams generated by an intense laser beam (Ulrich Schramm
)

CCD camera
“ STRAIGHT THROUGH”
DIRECTION
“BLOW-OFF”
DIRECTION
Protons
Protons
Al target
Cu activation stack
CPA pulse
Cu activation stack
Proton spectra using activation techniques

Proton Spectra from 100TW
Behind the target –
“straight through” direction
5 cm
BACK
In front of target
– “blow-off” direction
5 cm
FRONT

Experimental Arrangement
Multi Channel
Plates

Laser Irradiation of DOT Targets

Simulation of the experiment
2D-PIC simulation for following conditions:
I
L
= 3

10 19 W/cm 2 , 5 µm Ti-foil + 0.5 µm PMMA dot (20  20) µm 2

First „Monoenergetic“ Proton Beams from isolated water droplets
Ti-Sa laser pulse:
40 fs, 2

10 19 W/cm 2 , contrast 10 -8
1E8
20
 drop21053f forward Protons :
Thomson spectrometer
1E7
0.2
0.4
0.6 0.8 1 energy (MeV)
2 4
Important: laser pulse shape and target structure

Kirk Flippo, Tom Cowan et al

Snow Targets

Laser Irradiation of Snow targets

Electron acceleration in a capillary discharge waveguide
Lawrence Berkeley National Lab:
W. Leemans, B. Nagler, C. Tóth,
K. Nakamura, C. Geddes, E. Esarey,
C. Schroeder
Oxford University:
S. M. Hooker and A. J. Gonsalves
Waveguide:
Guiding of 40 TW laser pulses:
• in capillary discharge waveguide
• over 33 mm of plasma
Electron acceleration:
Generation of e-beams with:
• %-level energy spread
• mrad divergence
• Energy up to 1 GeV
Input spot Exit spot

Laser Beam

Laser driven PET isotope production
10 10
10 9
10 8
10 7
10 6
10 5
10 4
10 3
10 2
10 19 10 20
Irradiance (Wcm
-2  m
2
)
10 21
Activity as a function of laser intensity. The black and red hatched areas are for typical patient doses for 18 F and 11 C

Laser-driven phototransmutation of 129 I – a long lived nuclear waste product
• 129 I has a half-life of 15.7 x 10 6 years
• 128 I has a half-life of 25 mins
•
The transmutation was carried out using a laser driven (

, n) reaction

Nuclear activation: Experiment arrangement
Activation samples
Laser pulse
Resistively heated target
Iodine samples

(

,n) reaction in 129 I using a Ge detector to measure decay of 128 I

The Generation of Gamma ray light sources
• First of all you require GeV electron beams generated by lasers or by conventional linacs
• Compton backscatter laser photons to produce multi-MeV gamma ray beams.

IR-electron bunch collision
IR bunch
Electron bunch
First x-rays of collision produced when bunches 1 st meet.
A
Last x-rays of collision produced when bunches separate.
A
Z
X-rays A through Z travel at c with electron bunch.
Time
A s s x-rays electrons
=
Z
Courtesy George Neil, JLab

Peak brilliance of light sources with star of GRLS at 1MeV 15 orders of magnitude greater than all synchrotrons and FELS

GRLS)
Gamma ray resonant fluorescence
Mainland security
Nuclear waste reclassification

Storing radioactive waste at power stations
There are hundreds of thousands of such barrels world wide with very little knowledge of the contents.
GRLSs would enable certifiable classification of the waste contents

Depository of hundreds of drums of radioactive waste

Nuclear Resonance Fluorescence

Example of NRF spectra obtained from a plutonium target.

Level Scheme for Pu 239

This is a nuclear regime which is best carried out using lasers - opportunities at XFEL and ELI Bucharest

At present there is no laser induced reaction which cannot be done better using conventional accelerators – at high temperatures this could be very different

What do we intend to do at high temperatures – modification of the half life of 26 Al using the high temps produced by coincident laser driven particle beams

How do we make the Al 26 -use the PW short pulse laser to generate a proton beam and then use a Mg 26 (p,n)Al 26 reaction
Simultaneously heating with a laser produced gamma ray beam or thus a Mg 26 (pγ,n)Al 26 reaction

Al 26 Decay scheme

Level scheme
Skelton R et. al., Phys.Rev. C 35 (1),45,1987
Motivation
• 26 Al in the astrophysical context using a gamma camera
•
•
Interstellar abundance al.
, arXiv:astro-ph/0104047v1 et
Evolution of stellar abundance
Voss R et al.
, Astronomy & Astrophysics, 504 , 531, 2009

Schematic of laser plasma nuclear 26 Al experiment
Use the NIF PW laser at
10 22 W/cm 2 or VULCAN
'p-production pulse'
E driver
~15J
High temperature production pulse
(hard photon beam)
TSNA
I ~10 18-20 Wcm -2
26 Mg p
Shielding
Canvas
Diamond
Target
NaI or Ge

ORGAM Detector System

Laser Induced Fission of 238 U and
Nuclear Fission Yields as a Fn of Temp
Al-production target
Proton beam isochoric heated volume depleted 238 U thickness: 8μm encapsulated by Al-foils
Fission products & trajectories
Laser
~200μm
Front Al-sheet 1 thickness: 10μm isochoric heated
0-40μm variable
Al-U-Al sandwich target
Cu-stack
Back Al-sheet 2 thickness:10μm
This was an experiment to be carried out using short pulse laser isochoric heating but could be done by NIF heating

Nuclear Excitation in
Plasmas NEET/NEEC
Nuclear Opportunities at
XFEL 2015 and ELI