Possible topics for mini projects at the CDT.
X-ray tube characterisation. Geant4 simulation for dosimetry modelling
Conventional medical accelerators are able to produce electrons with energies up to 30-40 MeV, too low to penetrate deep into the human body. Higher energies are available from Laser Wakefield Accelerators, up to 200 MeV in 2 mm. Here we compare electron beam therapy with other standard types of irradiation, such as X-rays.
Electron therapy with laser-wakefield accelerators is complicated by the presence of X-rays coming from betatron oscillations in the plasma. It is important to quantify the dose contribution from the electrons and the dose contribution from the X-rays.
For this purpose, an X-ray tube should be characterised. The idea is to know the dose delivered by this tube as a function of the intensity and of the exposure time. As a first step towards the identification of the role of betatron radiation, an image plate (IP) calibration will be made using a conventional X-ray tube to obtain the dose as a function of IP counts.
Modelling the LHC collimation system
The collimation system at the LHC is essential for machine protection, and requires continuing development and understanding as the beam currents are increased in the next few years. We use the MERLIN library to do this, which requires the improved description of small angle scattering in the collimator jaws. This is done in collaboration with the Manchester accelerator group, and will also involve some travel to CERN to liaise with the machine group there.
Patients who are over 70 and suffering from the brain tumour glioblastoma multiforme (GBM) are normally treated paliatively. A clinical trial is underway at the University of Cambridge to look at the effects of offering more radical radiotherapy and chemotherapy to these patients. This project would involve using a model developed between University of Surrey and Addenbrookes Hospital on the clinical decision making process for treating (GBM) and modifying it to take account of the decisions being made during this clinical trial and using the outcomes of the trial to test the model. The project would involve working with the group at the University of Surrey and clinicians at the Addenbrookes Hospital
An investigation into Laser Plasma Density Interferometry as a diagnostic tool for laser driven accelerators
A comparative study between two interferometric techniques, Mach-Zender and Nomarski interferometers. The Nomarski interferometry employs a Wollaston prism for dividing the beam and has advantages of simplicity and the absence of alignment and stability problems. In Mach-Zener interferometer the probe beam follows a different path from a reference beam which are then recombined to form an interference pattern simplifying the interpretation of fringes. The primary goal is to design and test an interferometer for measuring the plasma electron density of laser induced plasma. The interferometer must be compact and reliable as physical space and beam time are limited assets.
PSI: ion beam radiotherapy
The project will be to investigate ion beam radiotherapy techniques using the facilities at the Paul Scherrer Institute (PSI) in Switzerland. PSI operates the only compact scanning-Gantry worldwide for proton radiation therapy of deep-seated tumours. The spot-scanning technique developed at PSI enables malignant tumours to be targeted with high precision deep inside in the body, and their growth successfully stopped, without damaging healthy tissue around the target area. By March 2008 320 patients have been treated at the Gantry 1, suffering from brain, head and neck, skull-base, spinal cord or abdominal tumours. The project would involve hands-on experience in patient treatment using the facility.
Ion Optics Modelling of the MIAMI Accelerator system
A new facility, the Microscope and Ion Accelerator for Materials Investigations (MIAMI), has recently been established at the University of Huddersfield which combines an ion beam system with a transmission electron microscope. The purpose of this is to allow the real-time study of the dynamic effects of ion beams on materials at the nanoscale. The ion accelerator operates at a potential of 100keV and can use double charged ions to achieve energies of up to 200 keV. One of the key challenges in operating this facility is to establish and maintain the intersection of an electron beam, ion beam and thin sample (below 100 nm) at the same point in three-dimensional space. The ion accelerator system includes the ion source, two einzel lenses, a bending magnet, a skimmer aperture and an electrostatic deflection system — this latter inside the electron microscope. It is important to know the precise path taken by the ion beam in order to optimise the focus and alignment of the beam. The ion beam is measured by two beam-profile monitors placed along the beamline, by the skimmer aperture and also by current measuring devices at or near the specimen position but these give an incomplete picture as to the true position, size and direction of the ion beam at any given point. This project will be to use the SIMION simulation package to arrive at a better understanding of the behaviour of the ion beam in the MIAMI ion accelerator. In order to achieve this goal the student will have to learn to use the simulation software and to develop computer aided design (CAD) skills.
Modelling proton dose delivery
In proton therapy treatment it is crucial that the dose specified by the clinician is actually delivered by the system of accelerator, gantry, and nozzle, in the right place and with the right intensity. The GEANT4 simulation code provides a sophisticated model of the transport and interactions of protons, and the TOPAS system, currently being developed at SLAC, matches the specifications provided by the machine vendors to the GEANT4 geometry. The project will use these packages to provide a system which can be used at the new proton therapy centre in Manchester which will enable verification of planned patient treatments.
Plasma radiography with laser-accelerated ions
The project will involve taking part to an experiment scheduled on the LULI2000 facility, to investigate the physics of colliding plasmas, and the possible formation of collisionless shocks in the process. This will be done by using , as the main diagnostic, proton radiography, employed a 30 MeV proton beam accelerated by a ps, 100 J laser pulse. Other diagnostics will include interferometry/shadowgraphy employing an optical probe. The student will take part to the preparation of the experiment, its implementation and to the analysis of the data, and will have the opportunity to acquire first hand expertise in an important application of laser-accelerated ions in one of the major European laser facilities.
Laser-driven neutron sources
The project will involve participating to an experiment investigating the production of neutrons from fusion reactions initiated by high intensity irradiations of solid targets. The experiment will be carried out with the world-leading VULCAN Petawatt laser facility. The student will also assist in the preparation of the experiment, and in data analysis, and is expected to acquire expertise in high-power laser operations, Montecarlo modeling and nuclear diagnostics.
Staging in high-gradient laser plasma acceleration
The training project will be part of the laser-plasma acceleration programme with self-injection currently under development at ILIL-INO-CNR. The programme includes the development of compact MeV accelerators for biomedical applications and the study of high-gradient, GeV scale high quality acceleration techniques. The MeV accelerator studies are carried out entirely at the ILIL lab at INO_CNR Pisa and focus on the standardization of a laser-plasma accelerator for dosimetric studies and comparison with conventional sources. The GeV scale studies are carried out using the FLAME laser facility at LNF-INFN Frascati. The project will include experimental activity at both locations and will concern mainly optical diagnostics of the laser-plasma interaction, including optical spectroscopy, imaging and interferometry.