313 research outputs found
Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress
It has been known for about sixty years that proton and heavy ion therapy is
a very powerful radiation procedure for treating tumours. It has an innate
ability to irradiate tumours with greater doses and spatial selectivity
compared with electron and photon therapy and hence is a tissue sparing
procedure. For more than twenty years powerful lasers have generated high
energy beams of protons and heavy ions and hence it has been frequently
speculated that lasers could be used as an alternative to RF accelerators to
produce the particle beams necessary for cancer therapy. The present paper
reviews the progress made towards laser driven hadron cancer therapy and what
has still to be accomplished to realise its inherent enormous potential.Comment: 40 pages, 24 figure
Orbital electron capture by the nucleus
The theory of nuclear electron capture is reviewed in the light of current understanding of weak interactions. Experimental methods and results regarding capture probabilities, capture ratios, and EC/Beta(+) ratios are summarized. Radiative electron capture is discussed, including both theory and experiment. Atomic wave function overlap and electron exchange effects are covered, as are atomic transitions that accompany nuclear electron capture. Tables are provided to assist the reader in determining quantities of interest for specific cases
In Situ Characterisation of Permanent Magnetic Quadrupoles for focussing proton beams
High intensity laser driven proton beams are at present receiving much
attention. The reasons for this are many but high on the list is the potential
to produce compact accelerators. However two of the limitations of this
technology is that unlike conventional nuclear RF accelerators lasers produce
diverging beams with an exponential energy distribution. A number of different
approaches have been attempted to monochromise these beams but it has become
obvious that magnetic spectrometer technology developed over many years by
nuclear physicists to transport and focus proton beams could play an important
role for this purpose. This paper deals with the design and characterisation of
a magnetic quadrupole system which will attempt to focus and transport
laser-accelerated proton beams.Comment: 20 pages, 42 figure
Study of photo-proton reactions driven by bremsstrahlung radiation of high-intensity laser generated electrons
Photo-nuclear reactions were investigated using a high power table-top laser. The laser system at the University of Jena ( I similar to 3-5 x 10(19) W cm(-2)) produced hard bremsstrahlung photons ( kT similar to 2(9 MeV) via a laser-gas interaction which served to induce ( gamma, p) and ( gamma, n) reactions in Mg, Ti, Zn and Mo isotopes. Several ( gamma, p) decay channels were identified using nuclear activation analysis to determine their integral reaction yields
The nuclear AC-Stark shift in super-intense laser fields
The direct interaction of super-intense laser fields in the optical frequency
domain with nuclei is studied. As main observable, we consider the nuclear
AC-Stark shift of low-lying nuclear states due to the off-resonant excitation
by the laser field. We include the case of accelerated nuclei to be able to
control the frequency and the intensity of the laser field in the nuclear rest
frame over a wide range of parameters. We find that AC-Stark shifts of the same
order as in typical quantum optical systems relative to the respective
transition frequencies are feasible with state-of-the-art or near-future laser
field intensities and moderate acceleration of the target nuclei. Along with
this shift, we find laser-induced modifications to the proton root-mean-square
radii and to the proton density distribution. We thus expect direct
laser-nucleus interaction to become of relevance together with other
super-intense light-matter interaction processes such as pair creation.Comment: 10 pages, 2 eps figure
Plasma–wall interaction in laser inertial fusion reactors: novel proposals for radiation tests of first wall materials
Dry-wall laser inertial fusion (LIF) chambers will have to withstand strong bursts of fast charged particles which will deposit tens of kJ m−2 and implant more than 1018 particles m−2 in a few microseconds at a repetition rate of some Hz. Large chamber dimensions and resistant plasma-facing materials must be combined to guarantee the chamber performance as long as possible under the expected threats: heating, fatigue, cracking, formation of defects, retention of light species, swelling and erosion. Current and novel radiation resistant materials for the first wall need to be validated under realistic conditions. However, at present there is a lack of facilities which can reproduce such ion environments. This contribution proposes the use of ultra-intense lasers and high-intense pulsed ion beams (HIPIB) to recreate the plasma conditions in LIF reactors. By target normal sheath acceleration, ultra-intense lasers can generate very short and energetic ion pulses with a spectral distribution similar to that of the inertial fusion ion bursts, suitable to validate fusion materials and to investigate the barely known propagation of those bursts through background plasmas/gases present in the reactor chamber. HIPIB technologies, initially developed for inertial fusion driver systems, provide huge intensity pulses which meet the irradiation conditions expected in the first wall of LIF chambers and thus can be used for the validation of materials too
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