REACCELERATION OF ION BEAMS FOR PARTICLE THERAPY

Abstract At the Heidelberg Ion-Beam Therapy Centre (HIT) more than 2000 cancer patients have been treated with ions using the raster-scanning method since 2009. The synchrotron provides pencil beams in therapy quality for more than 250 energy steps for each ion species allowing to vary the penetration depth and thus to irradiate the tumour slice-by-slice. So far, changing the beam energy necessitates a new synchrotron cycle, including all phases without beam extraction. As the number of ions that can be accelerated in the synchrotron usually exceeds the required number of ions for one energy slice, the duty cycle could be significantly reduced by reaccelerating or decelerating the remaining ions to the adjacent energy level. By alternating acceleration and extraction phases several slices could be irradiated with only short interruptions. This leads to a better duty cycle and a larger number of patients that can be treated in the same time. Therefore the behaviour of a reaccelerated but transversally blown up beam -due to the use of RF-knockout extraction -must be investigated in detail, beam losses have to be minimised. To estimate the potential benefit of such an operation mode, treatment time has been simulated and compared to the time achieved in the past. A reduction of more than 50 % is possible

Tunneling Spectra of Individual Magnetic Endofullerene Molecules

The manipulation of single magnetic molecules may enable new strategies for high-density information storage and quantum-state control. However, progress in these areas depends on developing techniques for addressing individual molecules and controlling their spin. Here we report success in making electrical contact to individual magnetic N@C60 molecules and measuring spin excitations in their electron tunneling spectra. We verify that the molecules remain magnetic by observing a transition as a function of magnetic field which changes the spin quantum number and also the existence of nonequilibrium tunneling originating from low-energy excited states. From the tunneling spectra, we identify the charge and spin states of the molecule. The measured spectra can be reproduced theoretically by accounting for the exchange interaction between the nitrogen spin and electron(s) on the C60 cage.Comment: 7 pages, 4 figures. Typeset in LaTeX, updated text of previous versio

Experimental densities and enthalpies for water - natural gas systems

Typescript (photocopy).A Burnett apparatus was used to obtain accurate P-(rho)-T data of water - natural gas systems over a pressure range of 5 to 2450 psia. Experimental data were obtained for three wet, sweet natural gas mixtures containing 1.85%, 5.0%, and 10.0%, water over a temperature range of 50(DEGREES) to 210(DEGREES)C. In addition, data were procured for three water and sour natural gas combinations of 0.0%, 5.5%, and 10.0% water over a temperature range of 50(DEGREES)C to 200(DEGREES)C. The Burnett-isochoric technique was used to minimize any adsorption errors. This technique enabled the coverage of an entire P((rho),T) surface with a single sample. The Burnett-isochoric method also provided a means for the accurate calculation of the thermophysical properties, such as enthalpies, densities, and compressibility factors, of the water - natural gas systems. The addition of small amounts of water to the natural gases provided mixtures that are near perfect over the pressure range of zero to 2450 psia. The compressibility factors range from 0.965 to 1.000. The Burnett-isochoric technique provided a means of the determination of the dew-point loci of the five wet, natural gas mixtures. Measurement of the abrupt change of the isochoric slope, ((PAR-DIFF) P/(PAR-DIFF) T)(,(rho)), at the boundary between the single-phase gas and the two-phase region supplied grid points of the dew-point loci. The dew-point loci of the wet, sweet natural gas mixtures generally agreed with a priori methods except at low pressures. The dew-point loci of the wet, sour natural gas mixtures provided higher dew-point pressures than the prediction methods, primarily due to lack of previously available precise experimental data

Shaped-charge tests in support of the coal-gasification program

The LLNL concept for in-situ coal gasification requires forming horizontal holes in deep coal beds to connect vertical bore shafts. These lateral holes are required to provide a passage for the gases between the vertical shafts. Shaped charges are being considered for producing these horizontal bore holes. This report describes a test method for evaluating new shaped charge designs and presents the results for three designs

Experimental densities and enthalpies for water - natural gas systems

Typescript (photocopy).A Burnett apparatus was used to obtain accurate P-(rho)-T data of water - natural gas systems over a pressure range of 5 to 2450 psia. Experimental data were obtained for three wet, sweet natural gas mixtures containing 1.85%, 5.0%, and 10.0%, water over a temperature range of 50(DEGREES) to 210(DEGREES)C. In addition, data were procured for three water and sour natural gas combinations of 0.0%, 5.5%, and 10.0% water over a temperature range of 50(DEGREES)C to 200(DEGREES)C. The Burnett-isochoric technique was used to minimize any adsorption errors. This technique enabled the coverage of an entire P((rho),T) surface with a single sample. The Burnett-isochoric method also provided a means for the accurate calculation of the thermophysical properties, such as enthalpies, densities, and compressibility factors, of the water - natural gas systems. The addition of small amounts of water to the natural gases provided mixtures that are near perfect over the pressure range of zero to 2450 psia. The compressibility factors range from 0.965 to 1.000. The Burnett-isochoric technique provided a means of the determination of the dew-point loci of the five wet, natural gas mixtures. Measurement of the abrupt change of the isochoric slope, ((PAR-DIFF) P/(PAR-DIFF) T)(,(rho)), at the boundary between the single-phase gas and the two-phase region supplied grid points of the dew-point loci. The dew-point loci of the wet, sweet natural gas mixtures generally agreed with a priori methods except at low pressures. The dew-point loci of the wet, sour natural gas mixtures provided higher dew-point pressures than the prediction methods, primarily due to lack of previously available precise experimental data

BIOPIXE: A new PIXE-data software package to analyse quantitative elemental distributions of inhomogeneous samples

A new software package "BIOPIXE" with emphasis on biological samples inhomogeneous in mass is presented. PIXE and STIM measurements were carried out on pixel-by-pixel basis. The elemental concentrations are evaluated using GUPIX. Main features of BIOPIXE are correction of thermal shifts during long time measurements (72 h), offline evaluation of elemental concentrations of arbitrary regions and, especially, true elemental maps of samples inhomogeneous in mass. (C) 2002 Published by Elsevier Science B.V

BIOPIXE: A new PIXE-data software package to analyse quantitative elemental distributions of inhomogeneous samples

A new software package "BIOPIXE" with emphasis on biological samples inhomogeneous in mass is presented. PIXE and STIM measurements were carried out on pixel-by-pixel basis. The elemental concentrations are evaluated using GUPIX. Main features of BIOPIXE are correction of thermal shifts during long time measurements (72 h), offline evaluation of elemental concentrations of arbitrary regions and, especially, true elemental maps of samples inhomogeneous in mass. (C) 2002 Published by Elsevier Science B.V