Lorenzo Torrisi

Bio: Lorenzo Torrisi is an academic researcher from University of Messina. The author has contributed to research in topics: Laser & Ion. The author has an hindex of 33, co-authored 474 publications receiving 5210 citations. Previous affiliations of Lorenzo Torrisi include Istituto Nazionale di Fisica Nucleare & University of Catania.

Tantalum ions produced by 1064 nm pulsed laser irradiation

Abstract: A Q-switched Nd:YAG (yttrium aluminum garnet) laser (1064 nm wavelength) with a 9 ns pulse width, 1–900 mJ pulse energy, and 0.5 mm2 target spot, is employed to irradiate tantalum targets in vacuum. The irradiation produces a strong etching of the metal and forms a plasma in front of the target. The plasma contains neutrals and ions with a high charge state and a wide energy distribution. Time-of-flight measurements are presented for the ionic production. A cylindrical electrostatic ion analyzer permits to measure the yield and the charge state of the emitted ions and to extrapolate the ion energy distribution as a function of the laser fluence in the range 10–100 J/cm2. The measurements indicate that at high laser fluence the tantalum charge state may reach 8+ and the maximum ion energy about 6 keV. The ion energy distribution is presented as a function of the charge state. It follows approximately a “shifted Maxwellian distribution.” A better theoretical approach has been further developed considering t...

Study on the ablation threshold induced by pulsed lasers at different wavelengths

Abstract: A study of the effects induced by pulsed laser ablation on different materials as a function of the laser wavelength is presented. In particular the ablation at low laser fluence, of the order of 10 8 –10 10 W/cm 2 with ns pulse width, is investigated experimentally on different metals, semiconductors and polymers. Two theoretical models, explain the experimental results about the fluence threshold value measurements, as depending on the laser wavelength are discussed. The photothermal process is valid for the estimation of the threshold fluence for IR and visible radiation, both inducing thermal heating in metals and semiconductors through the photon-free electron energy transfer. This model is not valid for polymers. The photochemical process is valid for the estimation of the threshold fluence for UV radiation, which photon energy is higher with respect to the chemical binding energy. This radiation induces chemical bond breaking in insulators and scission and cross linking effects can be produced. This last model is not valid for metals and semiconductors.

Plastic scintillator investigations for relative dosimetry in proton-therapy

Abstract: Plastic organic scintillators, polyvinyltoluene based, can be used with high sensitivity to detect 1–60 MeV proton beams. Thin scintillators can be applied to proton-therapy field as relative dosimeter thanks to their water-equivalent nature, high energy–light conversion efficiency, low dimensions and good proportionality to the absorbed dose at low stopping powers. Unfortunately, the quenching effect limits the use of the scintillators at high stopping powers. Moreover, they show a negligible radiation damage at the typical proton doses used in radiotherapy. Preliminary results have been obtained detecting in air both 60 MeV therapeutically proton beam at the Paul Scherrer Institute (PSI, Villigen-Zurich) and 24 MeV proton beam, at the Laboratorio Nazionale del Sud (LNS, Catania).

Handbook of Chemistry and Physics

Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants

Abstract: This paper reviews the past, present, and future of the hydroxyapatite (HAp)-based biomaterials from the point of view of preparation of hard tissue replacement implants. Properties of the hard tissues are also described. The mechanical reliability of the pure HAp ceramics is low, therefore it cannot be used as artificial teeth or bones. For these reasons, various HAp-based composites have been fabricated, but only the HAp-coated titanium alloys have found wide application. Among the others, the microstructurally controlled HAp ceramics such as fibers/whiskers-reinforced HAp, fibrous HAp-reinforced polymers, or biomimetically fabricated HAp/collagen composites seem to be the most suitable ceramic materials for the future hard tissue replacement implants.

Ion acceleration by superintense laser-plasma interaction

Abstract: Ion acceleration driven by superintense laser pulses is attracting an impressive and steadily increasing effort. Motivations can be found in the applicative potential and in the perspective to investigate novel regimes as available laser intensities will be increasing. Experiments have demonstrated, over a wide range of laser and target parameters, the generation of multi-MeV proton and ion beams with unique properties such as ultrashort duration, high brilliance, and low emittance. An overview is given of the state of the art of ion acceleration by laser pulses as well as an outlook on its future development and perspectives. The main features observed in the experiments, the observed scaling with laser and plasma parameters, and the main models used both to interpret experimental data and to suggest new research directions are described.

Nuclear Tracks in Solids (Principles and Applications)

Abstract: (1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.