PAC2013 - List of Authors (Posocco, P.A.)

Paper

Title

Page

Thermal Design of the FETS Chopper Beam Dump

303

P. Savage, M. Aslaninejad, P.A. Posocco, J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A.P. Letchford, J.K. Pozimski
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
S. Mishra
Imperial College of Science and Technology, London, United Kingdom

Funding: M. Shruti was supported by STFC/RAL.
The Front End Test Stand Project (FETS) at RAL is being built to demonstrate fast beam chopping. This is required to create precisely defined gaps in the bunched H⁻ beam which is essential in order to minimise beam losses in a synchrotron during injection. The gaps are created in the Medium Energy Beam Transport (MEBT) section of the FETS beam-line using a ‘fast-slow’ chopping scheme. This scheme uses two choppers, one fast and one slow, each kicks a portion of beam into its corresponding downstream beam dump. The challenge for the beam dump design is that it must occupy a limited longitudinal space to ensure that the beam transport is preserved and must absorb a beam power that is close to the sustainable stress limit of common engineering materials. This paper will describe the simulations made to study the cooling scheme required to absorb the power deposited in the dump plates for the fast and slow choppers.

WEOCB2

Next Generation of Radiobiology Experiments

P.A. Posocco, S.H. Tsang
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
H. Larose
The Imperial College of Science, Technology and Medicine, London, United Kingdom

Proton Therapy (PT) is a well-established cancer treatment, which has helped more than 10’000 patients in the world in the last year alone. The outcomes are very positive and for most patients PT yields much better results in terms of morbidity and tumour control than conventional Radio Therapy, because with protons it is possible to control more precisely the energy deposition inside the tumour. However, the understanding of the interaction between radiation and cells is fundamental to fully exploit this aspect, and therefore in-vitro and in-vivo experiments comparing the effect of protons and photons need to be carried out. In this paper we will critically explore the options provided by the research groups and facilities operating in this field and we will be compiling a list of desiderata for the next generation of accelerators used for these experiments.

Slides WEOCB2 [2.871 MB]

THPSM10

Analysis of Propagated Effects in Proton Depth-Dose Distribution Curves Due To Initial Beam Energy Spread

1403

P.A. Posocco, M. Aslaninejad, J.F. Piech, S. Zalel
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: S. Zalel was supported by the Anglo Israel Association.
Proton therapy treatment planning uses depth-dose distribution curves of single initial beam energies to create Spread spread Out Bragg Peaks (SOBP). These are used to target specific regions in the body. However, the initial energy spread of the beams leads to an uncertainty in beam energy, affecting the dose distribution. In this paper, previous work (M. Aslaninejad et al., 2011: 189–196) on the depth-dose distribution of proton beams using inelastic-collision cross sections of liquid water is extended into use with chromatic beams. The effect of the initial energy spread on depth-dose distribution curves, the distal dose and the SOBP are discussed. Limits on beam energy spread are suggested.

THPSM11

A Novel Solution for FFAG Proton Gantries

1406

J. Pasternak, M. Aslaninejad, P.R.N. Holland, P.A. Posocco, G.W. Walton
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

In the recent years FFAG gantries have been studied for medical applications, but none has so far been realised. The FFAG solution would reduce the complexity of beam line set-up, its weight and therefore the cost of the rotating support, in particular for heavy ions. The Imperial College London is using the experience gained in the Pamela Project and in the design and commissioning of EMMA to work on a solution of a non-scaling FFAG gantry, which fulfills the full requirements for the spot scanning - parallel beam treatment technique, and provides an easy interface to the upstream accelerator. The preliminary results will be presented in this paper.

THPSM12

A Ready-to-use Application of Laser-Plasma Accelerators using Gabor Lenses

1409

J.K. Pozimski, M. Aslaninejad, N. Dover, Z. Najmudin, R.M. Nichols, P.A. Posocco
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: R.M. Nichols was supported by EPSRC.
A realistic particle distribution for a proton beam generated by laser-plasma interaction is required in order to simulate its transport through a Gabor lens system intended for use in radiobiology experiments. A stack of radiochromic films were exposed to a laser-driven proton beam of 25 MeV at the Vulcan Petawatt Experiment at Rutherford Lab and subsequently analysed to find the energy deposited per film and therefore the energy spectrum of the beam. Combined with the information on the radial profile of the dose in the films, it was possible to generate an idealised particle distribution. This distribution was sampled and used as a realistic proton source in a simulation through the Gabor lens system published at IPAC’13, scaled down to 4 MeV to fit the radiobiology experiment requirements.

THPSM13

Characterisation of Nitrogen Clusters and Gas Jet Targets Under Varied Nozzle Geometries

1412

C. Hughes, N. Dover, Z. Najmudin, P.A. Posocco
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: C. Hughes was supported by the Ogden Trust.
Gas jets are widely used for targets in laser-plasma driven article acceleration experiments. Optimising the mechanism requires tailored gas jet density profiles. Therefore, high density gas profiles have been investigated and characterised using different types of nozzles: sonic, supersonic, slit and supersonic slit. Gas jet profile optimisation was examined using nozzles of different diameters while varying gas pressure between 0 and 100 bar and valve opening duration. Gas jets produced by the nozzles were characterised using an optical probe laser. The gas jet density profile was measured through interferometry which was captured using a CCD camera. A second camera was used to record the Rayleigh scattering from the laser to confirm the presence clustering in nitrogen at high pressures.

Paper	Title	Page
MOPMA05	Thermal Design of the FETS Chopper Beam Dump	303
	P. Savage, M. Aslaninejad, P.A. Posocco, J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom A.P. Letchford, J.K. Pozimski STFC/RAL, Chilton, Didcot, Oxon, United Kingdom S. Mishra Imperial College of Science and Technology, London, United Kingdom
	Funding: M. Shruti was supported by STFC/RAL. The Front End Test Stand Project (FETS) at RAL is being built to demonstrate fast beam chopping. This is required to create precisely defined gaps in the bunched H⁻ beam which is essential in order to minimise beam losses in a synchrotron during injection. The gaps are created in the Medium Energy Beam Transport (MEBT) section of the FETS beam-line using a ‘fast-slow’ chopping scheme. This scheme uses two choppers, one fast and one slow, each kicks a portion of beam into its corresponding downstream beam dump. The challenge for the beam dump design is that it must occupy a limited longitudinal space to ensure that the beam transport is preserved and must absorb a beam power that is close to the sustainable stress limit of common engineering materials. This paper will describe the simulations made to study the cooling scheme required to absorb the power deposited in the dump plates for the fast and slow choppers.

WEOCB2	Next Generation of Radiobiology Experiments
	P.A. Posocco, S.H. Tsang Imperial College of Science and Technology, Department of Physics, London, United Kingdom H. Larose The Imperial College of Science, Technology and Medicine, London, United Kingdom
	Proton Therapy (PT) is a well-established cancer treatment, which has helped more than 10’000 patients in the world in the last year alone. The outcomes are very positive and for most patients PT yields much better results in terms of morbidity and tumour control than conventional Radio Therapy, because with protons it is possible to control more precisely the energy deposition inside the tumour. However, the understanding of the interaction between radiation and cells is fundamental to fully exploit this aspect, and therefore in-vitro and in-vivo experiments comparing the effect of protons and photons need to be carried out. In this paper we will critically explore the options provided by the research groups and facilities operating in this field and we will be compiling a list of desiderata for the next generation of accelerators used for these experiments.
	Slides WEOCB2 [2.871 MB]

THPSM10	Analysis of Propagated Effects in Proton Depth-Dose Distribution Curves Due To Initial Beam Energy Spread	1403
	P.A. Posocco, M. Aslaninejad, J.F. Piech, S. Zalel Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: S. Zalel was supported by the Anglo Israel Association. Proton therapy treatment planning uses depth-dose distribution curves of single initial beam energies to create Spread spread Out Bragg Peaks (SOBP). These are used to target specific regions in the body. However, the initial energy spread of the beams leads to an uncertainty in beam energy, affecting the dose distribution. In this paper, previous work (M. Aslaninejad et al., 2011: 189–196) on the depth-dose distribution of proton beams using inelastic-collision cross sections of liquid water is extended into use with chromatic beams. The effect of the initial energy spread on depth-dose distribution curves, the distal dose and the SOBP are discussed. Limits on beam energy spread are suggested.

THPSM11	A Novel Solution for FFAG Proton Gantries	1406
	J. Pasternak, M. Aslaninejad, P.R.N. Holland, P.A. Posocco, G.W. Walton Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	In the recent years FFAG gantries have been studied for medical applications, but none has so far been realised. The FFAG solution would reduce the complexity of beam line set-up, its weight and therefore the cost of the rotating support, in particular for heavy ions. The Imperial College London is using the experience gained in the Pamela Project and in the design and commissioning of EMMA to work on a solution of a non-scaling FFAG gantry, which fulfills the full requirements for the spot scanning - parallel beam treatment technique, and provides an easy interface to the upstream accelerator. The preliminary results will be presented in this paper.

THPSM12	A Ready-to-use Application of Laser-Plasma Accelerators using Gabor Lenses	1409
	J.K. Pozimski, M. Aslaninejad, N. Dover, Z. Najmudin, R.M. Nichols, P.A. Posocco Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: R.M. Nichols was supported by EPSRC. A realistic particle distribution for a proton beam generated by laser-plasma interaction is required in order to simulate its transport through a Gabor lens system intended for use in radiobiology experiments. A stack of radiochromic films were exposed to a laser-driven proton beam of 25 MeV at the Vulcan Petawatt Experiment at Rutherford Lab and subsequently analysed to find the energy deposited per film and therefore the energy spectrum of the beam. Combined with the information on the radial profile of the dose in the films, it was possible to generate an idealised particle distribution. This distribution was sampled and used as a realistic proton source in a simulation through the Gabor lens system published at IPAC’13, scaled down to 4 MeV to fit the radiobiology experiment requirements.

THPSM13	Characterisation of Nitrogen Clusters and Gas Jet Targets Under Varied Nozzle Geometries	1412
	C. Hughes, N. Dover, Z. Najmudin, P.A. Posocco Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: C. Hughes was supported by the Ogden Trust. Gas jets are widely used for targets in laser-plasma driven article acceleration experiments. Optimising the mechanism requires tailored gas jet density profiles. Therefore, high density gas profiles have been investigated and characterised using different types of nozzles: sonic, supersonic, slit and supersonic slit. Gas jet profile optimisation was examined using nozzles of different diameters while varying gas pressure between 0 and 100 bar and valve opening duration. Gas jets produced by the nozzles were characterised using an optical probe laser. The gas jet density profile was measured through interferometry which was captured using a CCD camera. A second camera was used to record the Rayleigh scattering from the laser to confirm the presence clustering in nitrogen at high pressures.