The ionoluminescence apparatus at the LABEC external microbeam facility

In this paper, we describe the main features of the ionoluminescence (IL) apparatus recently installed at the external scanning microbeam facility of the 3 MV Tandetron accelerator of the INFN LABEC Laboratory in Firenze. The peculiarity of this IL set-up resides in the fact that the light produced by the ion irradiation of the specimen is collected by a bifurcated optical fiber, so that photons are shunted both to a CCD spectrometer, working in the 200-900 nm wavelength range, and to a photomultiplier (PMT). The accurate focusing of the optical system allows high photon collection efficiency and this results in rapid acquisition of luminescence spectra with low ion currents on luminescent materials; simultaneously, luminescence maps with a spatial resolution of 10 μm can be acquired through the synchronization of PMT photon detection with the position of the scanning focused ion beam. An optical filter with a narrow passband facing the photomultiplier allows chromatic selectivity of the luminescence centres.The IL apparatus is synergistically integrated into the existing set-up for ion beam analyses (IBA). The upgraded system permits simultaneous IL and PIXE/PIGE/BS measurements. With our integrated system, we have been studying raw lapis lazuli samples of different known origins and precious lapis lazuli artworks of the Collezione Medicea of Museum of Natural History, University of Firenze, aiming at characterising their composition and provenance.     

Recent developments of ion beam induced luminescence at the external scanning microbeam facility of the LABEC laboratory in Florence

A new ionoluminescence (IL) apparatus has been successfully installed at the external scanning microbeam facility of the 3 MV Tandetron accelerator of the INFN LABEC in Firenze; the apparatus for photon detection has been fully integrated in the existing ion beam analysis (IBA) set-up, for the simultaneous acquisition of IL and PIXE/PIGE/BS spectra and maps.The potential of the new set-up is illustrated in this paper by some results extracted by the analysis of art objects and advanced semiconductor materials. In particular, the adequacy of the new IBA set-up in the field of cultural heritage is pointed out by the coupled PIXE/IL micro-analysis of a lapis lazuli stone; concerning applications in material science, IL spectra from a N doped diamond sample were acquired and compared with CL analyses to evaluate the relevant sensitivities and the effect of ion damage.     

Detectors for microbeam applications at medium ion energy

Nuclear microprobes with excellent lateral resolution can be realized using a liquid metal ion source and electrostatic einzel lens system in a few hundred keV energy range. In case of ion beam analysis it is better to provide a special detector for Rutherford Backscattering (RBS) analysis or elastic recoil detection. Good mass and depth resolutions should be attained while keeping the damage caused by the beam at tolerable level. Two solutions are considered in the present work: (1) toroidal electrostatic analyzer combined with simultaneous Time-of-Flight (TOF) measurement for mass identification; (2) TOF measurement only, using a large area microchannel plate. Both solutions can be combined with 2D position sensitive anode plates for excellent performance. In case of the first solution, it is possible to distinguish the different mass atoms by the scattering angle where their peak in the angular distribution appears. Similarly to the energy distribution at a fixed scattering angle the angular distribution at a fixed energy represents mass and depth distribution. In case of the second solution the huge acceptance angle will make it possible to analyze submicron spot size without serious beam effects and both heavy and light elements can be investigated.     

Heavy-ion microbeam system for cell irradiation at Kyoto University

We have developed a heavy-ion microbeam system for cell irradiation that uses an 8-MV tandem Van de Graaff accelerator at Kyoto University. Using a pair of apertures as the final collimator, microbeams of carbon, fluorine, and silicon were extracted to the atmosphere with few background particles. We used a thin transmission scintillator and a photomultiplier detector to accurately measure the number of extracted particles. To examine beam spreading, the beam profile was measured by observing tracks of an irradiated CR-39 track detector. The two disks with holes which were added to the collimating apertures reduced background radiation due to secondary X-rays and electrons from the apertures.     

The new CERN-ISOLDE on-line mass-separator facility at the PS-Booster

The ISOLDE on-line isotope separators have been operated since 1967 at the CERN-SC. This 600 MeV proton synchro-cyclotron had to be shut down in December 1990 after 33 years of service and it was decided to move ISOLDE to a new experimental area. The new on-line mass-separator facility is now under construction at the CERN PS-Booster. This accelerator provides an average current of about 2 μA of 1 GeV protons in very short high intensity pulses at low repetition rate. The beam can hit either one of the two target stations, the general purpose separator (GPS), a reconstructed ISOLDE-2 type machine (which can deliver beams simultaneously into three beam lines), and the high resolution separator (HRS), which is essentially the slightly modified ISOLDE-3 separator. The central GPS beam line and the HRS feed a common beam transport system to which most of the experiments will be connected. The new facility will be taken into operation in spring 1992.     

Radiative capture of nucleons at astrophysical energies with single-particle states

Radiative capture of nucleons at energies of astrophysical interest is one of the most important processes for nucleosynthesis. The nucleon capture can occur either by a compound nucleus reaction or by a direct process. The compound reaction cross sections are usually very small, especially for light nuclei. The direct capture proceeds either via the formation of a single-particle resonance or a non-resonant capture process. In this work we calculate radiative capture cross sections and astrophysical S-factors for nuclei in the mass region A<20 using single-particle states. We carefully discuss the parameter fitting procedure adopted in the simplified two-body treatment of the capture process. Then we produce a detailed list of cases for which the model works well. Useful quantities, such as spectroscopic factors and asymptotic normalization coefficients, are obtained and compared to published data.     

The Columbia University proton-induced soft x-ray microbeam

A soft X-ray microbeam using proton-induced X-ray emission (PIXE) of characteristic titanium (K_α 4.5 keV) as the X-ray source has been developed at the Radiological Research Accelerator Facility (RARAF) at Columbia University. The proton beam is focused to a 120 μm × 50 μm spot on the titanium target using an electrostatic quadrupole quadruplet previously used for the charged particle microbeam studies at RARAF. The proton induced X-rays from this spot project a 50 μm round X-ray generation spot into the vertical direction. The X-rays are focused to a spot size of 5 μm in diameter using a Fresnel zone plate. The X-rays have an attenuation length of (1/e length of ∼145 μm) allowing more consistent dose delivery across the depth of a single cell layer and penetration into tissue samples than previous ultrasoft X-ray systems. The irradiation end station is based on our previous design to allow quick comparison to charged particle experiments and for mixed irradiation experiments.     

The pulsed beam facility at the Tandetron accelerator in Florence

An electrostatic chopper has been installed in the LABEC laboratory (Sesto Fiorentino) along one of the beamlines of the new Tandetron accelerator. The chopper allows us the creation of a pulsed beam, from a continuous one, with a variable and finely controllable number of particles in each pulse. The facility can be tuned to obtain an average of one ion per pulse. This feature allows us the study of the basic processes of particle-target interactions, useful when performing ion beam analysis. Increasing the beam current, bunches up to thousands of ions can be obtained with a total energy being always an integer multiple of the one of the single ion. This configuration can be employed e.g. in a detector energy calibration.     

The new nuclear reaction analysis facility at the Lund Nuclear Microprobe

A versatile system for the analysis of the light elements at a Nuclear Microprobe has been constructed. Special reactions for analysis of H (H(p,p)H), Li (⁷Li(p,)), B (¹¹B(p,)2) and F (¹⁹F(p,₁e⁻e⁺)¹⁶O)as well as the general techniques pNRA, PIXE and STIM are employed simultaneously. The set-up is mainly, but not only, intended for thin samples.     

Progress of in-air microbeam system at the Wakasa Wan Energy Research Center

Modifications of an in-air microbeam system at the Wakasa Wan Energy Research Center designed to improve its performance are described. In the previous setup, a silicon nitride membrane (area: 1 × 1 mm²; thickness: 100 nm) was used for the beam exit window and the distance between the window and the sample was restricted to ?1.7 mm. Due to this restriction, the beam spot size obtained using the previous setup was 13 × 13 μm². To reduce the beam spot size, the beam exit window was replaced by a silicon nitride membrane (area: 3 (horizontal) × 2 (vertical) mm²; thickness: 200 nm). In this setup, the sample can be moved as close as 0.7 mm to the window, enabling a beam spot size of 7 × 6 μm² to be achieved. An additional Si-PIN X-ray detector was installed to estimate the relative number of beam particles. It detects X-rays from the beam exit window. The number of the X-rays from the beam exit window (which is proportional to the number of beam particles) is used for quantitative analysis and for online monitoring of the beam current. This system has the potential to be used for simultaneous particle-induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) measurements and for studying dental medicine.     

An industrial SR TXRF facility at ESRF

A TXRF industrial facility for the mapping of trace impurities on the surface of 300 mm Silicon wafers is presently under construction at the ESRF, European Synchrotron Radiation Facility, in Grenoble (France) and its commissioning phase will start at the end of 1998. The elements to be detected range from Na to Hg with a target routine detection limit of 10⁸ atoms /cm². The facility is the result of a collaboration between the ESRF and some of the major European semiconductor companies in the framework of the MEDEA consortium. Preliminary experiments at ESRF reached a detection limit of 1.7 × 10⁸ for Ni atoms (17 fg) in not optimised experimental conditions. The facility will improve the detection limit by a factor of 50. However, this gain in sensitivity will be traded in the possibility of mapping the surface of 300 mm wafer with a resolution of 500 pixels and a throughput of three wafers/h.     

A 3 MV tandetron facility at KFUPM

A 3 MV General lonex Tandetron accelerator has recently been tested at the nearly established Energy Resarch Laboratory at the King Fand University of Petroleum and Minerals. The accelerator features a very stable solid-state power supply which delivers about 3 MV of terminal high voltage. A beam resolution of about 400 eV was measured. Ions of a wide range of masses, ranging from hydrogen to gold, were accelerated. The configuration of this Tandetron will be described along with a discussion of the facility and research programs.     

Ion microbeam radiation system

An ion microbeam radiation test system has been built for studying radiation-induced charge collection and single event upsets in advanced semiconductor circuits. With this system, it is possible to direct an ion beam of a diameter as small as 1 μm onto a circuit or test structure with a placement accuracy of 1 μm. The components of the system and its operation are described. Applications are described which demonstrate the capabilities of the system     

Nanosecond pulsed proton microbeam

We show the preparation of a pulsed 20 MeV proton beam at the Munich tandem accelerator which offers a fluence of more than 1 × 10⁹ protons/cm² being deposited in a beam spot smaller than 100 μm in diameter and within a time span of 0.9 ns fwhm. Such a beam is produced by an ECR type proton source using charge exchange in cesium vapor to obtain a beam of negative hydrogen of high brightness that is bunched, chopped, accelerated and then focused by the superconducting multipole lens of the microprobe SNAKE. Single beam pulses are generated in order to irradiate cell samples or tissue and to measure their biological effect in comparison to continuous proton or X-ray irradiation.     

Ion source improvements at the Jena C-AMS facility

We report on an ongoing program of improvements of the Jena AMS system. The present contribution focuses on the improvement of the High Voltage Engineering Europe (HVEE) ion source 846. Furthermore it is described how the usable current range is determined at the Jena lab.     

Targets and ion sources at the TISOL facility

The TISOL thick target, on-line isotope separator is now operational at the TRIUMF facility with an active experimental program. A series of newly developed, target materials coupled with two different ion sources can now produce a wide range of isotopes. Radioactive beams of isotopes of He, C, N, O, Ne, Cl, Ar, Kr and Xe are now available in significant amounts from the first ECR (electron cyclotron resonance) ion source directly coupled to a multipurpose ISOL device. In addition, a surface ionization source with good yields for radioactive isotopes of Li, Na, Al, Ga, Rb, In, Cs, Yb and Fr is also available. Special emphasis has been given to the development of target materials, in particular light mass powder or pellet targets such as SiC and MgO. In addition, a newly developed zeolite (NaSiAlO₄) target shows properties which make it an optimal choice for producing isotopes near stability for nuclear astrophysics experiments with accelerated radioactive beams. Source and target developments at the upgraded TISOL facility will be presented.     

Technical developments at the KIT gyrotron test facility

Parasitic beam tunnel oscillations have been discovered on some of the series production gyrotrons for W7-X and also on the coaxial pre-prototype gyrotron for ITER. Solutions to remedy these problems have resulted in a modified beam tunnel design, technologically close to the existing beam tunnel. The new design has successfully been tested on both the coaxial and also the f-step-tunable gyrotrons and has subsequently been implemented on one of the W7-X series-production-tubes presently undergoing factory acceptance tests in Karlsruhe.The ECRH test loads at KIT are operated under normal atmospheric conditions. Several loads have eventually failed in 1 MW long pulse experiments and KIT has therefore started to design its own loads. The first KIT-load is based on a fixed conical mirror and an aluminum cylinder coated with a lossy material for increased absorption. The new load has so far successfully been used during the acceptance tests of two 1-MW CW gyrotrons. Nevertheless a new load based on pure (uncoated) stainless steel absorbers is being developed as a backup solution for the ongoing high priority gyrotron testing.A superconducting magnet capable of rapid field changes between 4.15 and 5.67 T for frequency step-tunable gyrotrons has been procured, has demonstrated a (static) field of 7.2 T and its capability of rapid field-changes.