Resonance Formation in Two-Photon Collisions

Two-photon collisions at the e$^+$e$^-$ colliders allow to investigate the formation and the properties of resonant states in a very clean experimental environment. A remarkable number of new results have been recently obtained giving important contributions to meson spectroscopy and glueball searches. The most recent results from the LEP collider at CERN and CESR at Cornell are reviewed here.Comment: 10 pages, invited talk presented at Meson2000, Cracow, Poland, May 200

Two-Photon Physics at LEP

A remarkable number of studies have been performed at LEP in the field of two-photon physics in the last four years. These results represent a very important contribution to the understanding of strong interactions at low energies. In particular, significant deviations from QCD predictions are found in the cross sections of inclusive single particle, jet and beauty production. A concise review of some of these results is presented.Comment: Presented at IFAE 2003, Lecce, Italy, 23-26 April, 200

The K0sK0s Final State in Two-Photon Collisions and Some Implications for Glueball Searches

The K0sK0s final state in two-photon collisions is studied with the L3 detector at LEP using data at centre of mass energies from 91 GeV to 183 GeV. The K0sK0s mass spectrum is dominated by the formation of the f_2'(1525) tensor meson whose two-photon partial width is measured. Clear evidence for destructive f_2-a_2 interference is observed. No signal is present in the region around 2.2 GeV. An upper limit for the two-photon partial width times the K0sK0s branching ratio of the \xi(2230) glueball candidate is then derived. An enhancement is observed around 1750 MeV. It may be due to the formation of a radial recurrence of the f_2'(1525) or to the s\bar{s} member of the 0++ meson nonet.Comment: 7 pages, 5 figures, Invited contribution to LEAP98, Villasimius, Italy, September 199

Scientific and Technological Development of Hadrontherapy

Hadrontherapy is a novel technique of cancer radiation therapy which employs beams of charged hadrons, protons and carbon ions in particular. Due to their physical and radiobiological properties, they allow one to obtain a more conformal treatment with respect to photons used in conventional radiation therapy, sparing better the healthy tissues located in proximity of the tumour and allowing a higher control of the disease. Hadrontherapy is the direct application of research in high energy physics, making use of specifically conceived particle accelerators and detectors. Protons can be considered today a very important tool in clinical practice due to the several hospital-based centres in operation and to the continuously increasing number of facilities proposed worldwide. Very promising results have been obtained with carbon ion beams, especially in the treatment of specific radio resistant tumours. To optimize the use of charged hadron beams in cancer therapy, a continuous technological challenge is leading to the conception and to the development of innovative methods and instruments. The present status of hadrontherapy is reviewed together with the future scientific and technological perspectives of this discipline.Comment: Presented at the 11th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications, Como (Italy), October 200

Nuclear Emulsion Film Detectors for Proton Radiography: Design and Test of the First Prototype

Proton therapy is nowadays becoming a wide spread clinical practice in cancer therapy and sophisticated treatment planning systems are routinely used to exploit at best the ballistic properties of charged particles. The information on the quality of the beams and the range of the protons is a key issue for the optimization of the treatment. For this purpose, proton radiography can be used in proton therapy to obtain direct information on the range of the protons, on the average density of the tissues for treatment planning optimization and to perform imaging with negligible dose to the patient. We propose an innovative method based on nuclear emulsion film detectors for proton radiography, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. Nuclear emulsion films interleaved with tissue equivalent absorbers can be fruitfully used to reconstruct proton tracks with very high precision. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam at PSI. The scanning of the emulsions has been performed at LHEP in Bern, where a fully automated microscopic scanning technology has been developed for the OPERA experiment on neutrino oscillations. After track reconstruction, the first promising experimental results have been obtained by imaging a simple phantom made of PMMA with a step of 1 cm. A second phantom with five 5 x 5 mm^2 section aluminum rods located at different distances and embedded in a PMMA structure has been also imaged. Further investigations are in progress to improve the resolution and to image more sophisticated phantoms.Comment: Presented at the 11th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications, Como (Italy), October 200

X-Ray and Mössbauer Study of Magnetic Black and from Mayotte Island

Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on several factors occurred during their formation. A sample of black sand was collected on the seashore of the island of Mayotte in the Indian Ocean and its magnetic part was investigated by means of energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and Mössbauer spectroscopy at room temperature. The mineral composition is dominantly magnetite, in good agreement with samples collected in other sites of volcanic origin. Contrary to pure magnetite, a relevant fraction of Ti was detected by EDS. The 16% Ti and 1% Mn content increase the magnetite lattice parameter to 8.4312 (25) Å. The broadening of XRD lines pointed towards a significant degree of disorder. This was confirmed by Mössbauer spectroscopy and is attributed to the presence of Ti replacing Fe in the magnetite lattice. The presence of Ti modifies the local magnetic field on the Fe sites, leading to a broader and more complex Mössbauer transmission spectrum with respect to the one of pure magnetite. To study the effect of temperature, samples were heated for 12 hours to 600˚C and 800˚C in argon and to 1000˚C in air. Annealing in argon did not improve the crystallinity while annealing in air caused a complete decomposition of magnetite into hematite and pseudobrookite

A novel experimental approach to characterize neutron fields at high- and low-energy particle accelerators.

The characterization of particle accelerator induced neutron fields is challenging but fundamental for research and industrial activities, including radiation protection, neutron metrology, developments of neutron detectors for nuclear and high-energy physics, decommissioning of nuclear facilities, and studies of neutron damage on materials and electronic components. This work reports on the study of a novel approach to the experimental characterization of neutron spectra at two complex accelerator environments, namely the CERF, a high-energy mixed reference field at CERN in Geneva, and the Bern medical cyclotron laboratory, a facility used for multi-disciplinary research activities, and for commercial radioisotope production for nuclear medicine. Measurements were performed through an innovative active neutron spectrometer called DIAMON, a device developed to provide in real time neutron energy spectra without the need of guess distributions. The intercomparison of DIAMON measurements with reference data, Monte Carlo simulations, and with the well-established neutron monitor Berthold LB 6411, has been found to be highly satisfactory in all conditions. It was demonstrated that DIAMON is an almost unique device able to characterize neutron fields induced by hadrons at 120 GeV/c as well as by protons at 18 MeV colliding with different materials. The accurate measurement of neutron spectra at medical cyclotrons during routine radionuclide production for nuclear medicine applications is of paramount importance for the facility decommissioning. The findings of this work are the basis for establishing a methodology for producing controlled proton-induced neutron beams with medical cyclotrons