J.A. van der Heide

A new approach to target chemistry for the iodine-123 production via the 124Te(p, 2n) reaction.

Abstract A method is described for a routine production of sizeable quantities of iodine-123 for medical diagnosis. The iodine-123 is produced via a (p, 2n) reaction on enriched tellurium-124 targets. Results are presented for relevant excitation functions. A new approach to target chemistry—comprising target preparation, separation of tellurium and carrier-free radioiodine, and target-material recovery—is presented. Irradiation techniques and chemical procedures are described in some detail.

Measurement of very-low sodium-vapor densities by means of optical resonance fluorescence

The sensitivity of the resonance-fluorescence method for the measurement of very-low sodium-vapor densities (<1010 atoms/cm3) has been studied. Light from a sodium spectral lamp is sent through a sodium-containing vessel, whose temperature can be varied. The vapor density has been measured in the region of 47–146 °C. At 47 °C, the vapor density is about 107 atoms/cm3. The measurements were performed with both a photon-counting device and a lock-in amplifier. The experimental results have been normalized to absolute density data given in the literature. Fitting our points to the equation logN = a + b/T yields the values a = 23.715 and b = −5257.7 K.

Topographic PIXE analysis of platinum levels in kidney slices from CIS-platin treated patients

Abstract Concentrations of platinum and several other trace elements have been measured exploiting a 50 × 50 μ proton beam for PIXE analysis. The thickness of a selective germanium absorber for the spectral resolution of platinum L β and selenium K α peaks optimized, taking into account the fluorescent X-rays excited in the absorber material. The measurements have been performed in the framework of a project on the assessment of the toxicity of cytostatic platinum compounds. The lateral distributions of platinum in human kidneys and in dog tissues were measured. The highest concentrations of platinum were seen in arterial walls, followed by glomeruli and tubules. Chronic kidney damage may be correlated to this pattern of retention.

The Determination of Platinum in Human Tissues with PIXE

Platinum levels as well as trace element concentrations in samples from cis-platin treated patients have been measured using the PIXE technique. The results were verified by neutron activation analysis for some elements. Spectral interferences of the platinum Lß peak and selenium K¿ have been solved by introducing a germanium layer as a selective absorber. The experiments are done in the frame work of a project on the assesment of the toxicity of cytostatic platinum compounds. Preliminary results for liver, kidney and heart tissues are shown.

Improvements of the eindhoven proton microbeam

The EUT microbeam is produced from a cyclotron beam by a 1×1 mm object diaphragm and a quadruplet lens system of high demagnification. To limit the effect of chromatic aberrations the beam energy spread can be reduced by tuning the beam transport system to a dispersive mode and the aperture of the lens system can be reduced. With the transport system in the normal achromatic mode, using 3.5 MeV protons a spot of 60×40 μm with a beam current of 150 nA is obtained. In the dispersive mode a spot of 10×10 μm with a beam current of 2 nA can be achieved. The microprobe is used for scanning PIXE analysis and three dimensional NRA and RBS.

Trace Element Mapping of Biological Tissues Using PIXE and XRF

For the measurement of the distributions of trace elements concentrations in biological samples the PIXE technique as well as the fluorescence of synchrotron radiation can be applied. At the Eindhoven University of Technology and the Free University of Amsterdam a PIXE microbeam facility has been used for analysis in a scanning mode of biological tissues. At the Synchrotron Radiation Source in Daresbury UK an XRF station for several mm beamsizes, equipped with a graphite mosaic crystal as a monochromator has been built. An x-ray microbeam facility with a silicon concave mirror as a focussing device is in Daresbury under construction now. Due to the specific machine features synchrotron radiation is favourite for the analysis of lighter elements with atom number 9

Target charging in pixe analysis

Abstract The effect of an increased spectral background occurring for PIXE analysis of non-conducting materials has been investigated experimentally. For this purpose the X-ray counting rate as a function of time has been measured under various analysis conditions of thick granite targets. A clear picture of the origin of the increased background can be gathered from the results.

The Eindhoven minicyclotron project ILEC

Abstract An isochronous low energy cyclotron for accelerating protons to a fixed energy of 3 MeV is under construction at Eindhoven University of Technology. The objectives of this project are: (1) to study the central region geometry, (2) to study space charge effects and their influence on beam properties, (3) to produce intense ion beams with low energy spread, (4) to apply it as a microprobe facility for element analysis. The main features of this cyclotron are a fourfold symmetrical magnetic AVF field; a double 50° dee system for 2nd harmonic excitation, as well as a double 30° dee system for 6th harmonic flat topping. The gap between the pole faces varies from 33.3 to 50.0 mm and the pole diameter is 420 mm. Servicing is done easily by lifting the upper part of the magnet yoke. The total weight is 3 t and the power consumption amounts to 20 kW. The magnetic field needed a few corrections to the pole pieces before it met the design specifications. Its high frequency behaviour is being observed in a full-scale model at reduced voltages.

A minicyclotron for a scanning proton muprobe

The isochronous low-energy cyclotron ILEC is a small AVF-machine which has keen built for acceleration of protons to a fixed energy of 3 MeV. The total weight of the machine is 3 ton and its power consumption is about 20 kW. Apart from providing an experimental facility for machine research, a main objective of this accelerator project is to produce an intense ion beam with low energy spread for element analysis. For this purpose ILEC is equipped with a double 50° dee system for 2nd harmonic excitation at a frequency of 43.5 MHz and a high voltage amplitude of about 30 kV. To attain the requirement of low energy spread also a double 30° system for 6th harmonic flat topping has been constructed and will be installed soon. During the last year the Eindhoven scanning proton muprobe has been updated. The aim of the new design is to obtain a probe diameter of a few μm with a beam current of at least 100 pA. The main application will be the determination of trace elements in biological and medical samples at cellular and subcellular level. In combination with the detection of scattered particles, applications in the field of mu-electronics and materials science are foreseen.

IMPROVEMENTS IN THE TRANSMISSION OF A TANDEM ACCELERATOR.

Abstract First order calculations are given which were carried out to obtain a good optical matching of a polarized ion source to the 12 MeV H.V.E.C. tandem Van de Graaff of the Utrecht State University. Two alternative injection systems are compared with one another and a relative transmission figure is given. The influence of higher order effects may be diminished by relatively simple means. The ion injection energy may be decreased considerably without significant loss in transmission efficiency if this is required for constructional reasons.