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We outline the possible applications of newly developed single photon avalanche detectors (SPAD) operating at low voltage and fabricated in silicon planar technology, reporting on tests done with scintillators. We envisage the integration of large arrays of identical sensors, employing a common read-out mode in order to achieve a high resolution and high sensitivity solid state photomultiplier. The applications of such a device would be many, particularly if we consider that we are also working on the production of microoptical components, perfectly suited for the loss-less coupling of these photosensors to several light sources (lasers, ordinary and scintillating fibers, scintillators, optical devices), by exploiting the promising deep lithography with ions (DLI) technology. Crossed time-of-flight and charge measurements between SPADs and usual photomultipliers, coupled to scintillators, have allowed to compare their relative performance. Specific issues regarding the SPAD and the scintillating fiber readout are presented, also in view of possible applications in the field of particle/radiation tracking systems. Index Terms--Avalanche photodiodes, photodetectors, photomultipliers, scintillation detectors, timing.

We have developed two techniques for microscopic particle beam imaging and dose measurement, both based on scintillators. One employs a scintillating fiberoptic plate to display the two-dimensional beam transversal profile, the other makes use of a small scintillator optically coupled to a compact photomultiplier. We have proved the possibility of detection from single beam particles up to several nanoampere currents. Both the devices are successfully being exploited for on-line control of low and very low intensity proton beams, down to a beam size of < 50 [micro]m in the framework of deep lithography with protons oriented to the production of optical microcomponents. Index Terms--Beam diagnostics, microbeam, microoptics, lithography, photodetectors.

In the framework of the HADES (High Acceptance DiElectron Spectrometer) collaboration we are developing the Time Of Flight (TOF) wall subdetector. In order to efficiently select events with [e.sup.+][e.sup.-] pairs produced in the nuclear matter, the TOF wall must be able to resolve electrons from pions up to 0.5 GeV/c and from protons up to 2 GeV/c. Because the short flight path of about 2m requires a 100-150 ps time resolution, we are building a granular system made of scintillator rods readout on both ends by means of photomultipliers, capable of such performance.

In the framework of the EXCYT radioactive ion beam facility, now under development at LNS Catania, we have developed several devices for beam monitoring. These devices are mainly based on scintillator detectors and photosensors, since they should allow to reconstruct beam informations even when operating at very low intensity, where conventional electrical devices are no longer sensitive. This new class of devices promises to give a good reliability and robustness at a cheap price, and in some case it will also allow counting the beam particles one by one.

The performance of proximity focused and electrostatically focused Hybrid Photo Diodes in realistic experimental conditions is reported. We have performed our measurements by coupling these devices to scintillators, and exposing them to a 60Co source and to a 58Ni beam. Apparently surprising results have been obtained when measuring the performance in a magnetic field.

The compact heavy ion spectrometer MACISTE is going to be realized at the Laboratorio Nazionale del Sud - Catania (LNS). It should allow to resolve the single mass unit up to A[approximately equal to]70 and the single charge up to Z[approximately equal to]45 when operating on ions around 50 MeV/amu. Coupling this device with other multidetectors already installed at LNS will give access to a large series of experiments concerning the projectile-like and the quasi-fusion physics at intermediate energy.

At the Laboratori Nazionali del Sud (LNS), Catania, Italy, in the framework of digital radiography and ion beam diagnostics, the use of thin monocrystal scintillating plates made from CsI(Tl) has allowed us to obtain promising results in terms of high sensitivity, compactness, and handiness. In both techniques, a charge-coupled device camera is used to observe the light produced in the crystal when it is crossed by X-rays, in case of radiography, or by charged particles, in case of beam imaging. Spatial resolution has been measured with X-rays as a function of the plate thickness (100 [micro]m to 2 mm), and particular care has been taken in order to perform the imaging of low-intensity radioactive beams ([I.sub.beam] < [10.sup.5] pps) that will be produced with the EXCYT facility at LNS. Index Terms--Radioactive ion beam imaging, X-ray imaging.