An innovative plasma chamber for Electron Cyclotron Resonance Ion Sources (ECRIS) has been developed at INFN and will soon be installed and tested with the AISHa (Advanced Ion Source for Hadrontherapy) ion source. It consists in inserting a particular liner into the existing chamber, which allows an electrical segmentation of the internal walls of the chamber. The purpose of this system is to reduce the ion losses induced by the anisotropic diffusion mechanism, to improve the plasma confinement and thus to increase the overall performance of the ion source. In fact, in ECRIS plasmas, electrons mostly diffuse along magnetic field lines while ions mostly leak across the same lines. In particular, the inner walls of the plasma chamber are covered with 30 tiles, each one polarized to a proper positive voltage. The tiles are made of Al-6082 and anodized except for the surface directly facing the plasma. The anodizing process makes each tile electrically insulated from the others and from the plasma chamber while preserving the correct operation of the cooling system. The tiles are wrapped by 2 half-cylinders made of Al-6082 acting as shells. Some tiles are equipped of a temperature sensor and machined to allow the wiring of the entire system. In this work the results of the preliminary tests of the thermal and electrical behaviour of the active chamber and the future perspectives are presented.

The Advanced Ion Source for Hadrontherapy (AISHa) is an ECR ion source operating at 18 GHz, developed with the aim of producing high intensity and low emittance highly charged ion beams for hadrontherapy purposes. Due to its unique peculiarities, AISHa is a suitable choice for industrial and scientific applications. In the framework of the INSpIRIT and IRPT projects, in collaboration with Centro Nazionale di Adroterapia Oncologica (CNAO), new candidates for cancer treatment (including metal ion beams) are being developed. Moreover, within the IONS experiment, AISHa will be the test-bench for the development of an innovative active plasma chamber designed to increase plasma confinement by changing plasma fluxes. OES technique will be also used to refine techniques of non-invasive plasma diagnostics. Finally, a dedicated setup is under realization to provide impinging beams and detection systems for target production in nuclear physics experiments.

The linear electromagnetic interaction between innovative hybrid metallo-dielectric nanostructured targets and laser in visible and IR range is investigated through numerical simulations. The obtained results rely on the optimization of a target based on metallic nanowires (NWs) to enhance light absorption in the visible range of the electromagnetic spectrum. The NWs are grown within the ordered nanoholes of an alumina substrate, thus, forming a plasmonic lattice with triangular symmetry. The remaining volume of the nanoholes on top of the NWs is sealed with a transparent layer of aluminum oxide that is suitable to be chemically modified for containing about 25% of deuterium atoms. The study presented here is carried out within the framework of a scientific program named PLANETA (Plasmonic Laser Absorption on Nano-Engineered Targets) aiming at investigating new laser–matter interaction schemes in the ns domain and for nuclear fusion purposes, involving especially the D–D reaction.

Auxiliary electrons can be successfully used as a diagnostic probe to deduce characteristics and dynamics of magnetically confined plasmas typical of Electron Cyclotron Resonance and Microwave Discharge Ion Sources, as well as to improve their performances and/or stability. To this scope, numerical simulations are a powerful tool to predict the effect of the interaction of an electron beam with the plasma: this paper presents an alternative way to deduce the plasma density by joining the results of numerical simulations with the diagnostic of the beam transmitted through the plasma. As will be shown, the applied numerical code is able to describe the dynamics of an electron beam, generated by an e-gun, propagating inside a plasma trap, with a magnetic configuration typical of microwave discharge ion sources, focusing on several effects such as ionizations, heating, space charge etc. The role played by the position of the e-guns with respect to the magnetic field profile will be also underlined.

This work aim to prepare a program of studies on nuclear physics and astrophysics, which will be conducted at the new ELI-NP Laser facility, which actually is under construction in Bucharest, Romania. For the arguments treated, such activity has required also a multidisciplinary approach and knowledge in the fields of nuclear physics, astrophysics, laser and plasma physics join with also some competences on solid state physics related to the radiation detection. A part of this work has concerned to the experimental test, which have been performed in several laboratories and in order to study and increase the level of knowledge on the different parts of the project. In particular have been performed studies on the laser matter interaction at the ILIL laboratory of Pisa Italy and at the LENS laboratory in Catania, where (by using different experimental set-ups) has been investigated some key points concerning the production of the plasma stream. Test has been performed on several target configurations in terms of: composition, structure and size. All the work has been devoted to optimize the conditions of target in order to have the best performance on the production yields and on energies distribution of the inner plasma ions. A parallel activity has been performed in order to study the two main detectors, which will constitute the full detections system, which will be installed at the ELI-NP facility.

A search for the direct production of Higgs bosons in the di-tau decay mode is performed with 86.3±3.5 pb−1 of data collected with the Collider Detector at Fermilab during the 1994–1995 data taking period of the Tevatron. We search for events where one tau decays to an electron plus neutrinos and the other tau decays hadronically. We perform a counting experiment and set limits on the cross section for supersymmetric Higgs boson production where tanβ is large and mA is small. For a benchmark parameter space point where mA0=100 GeV/c2 and tanβ=50, we limit the production cross section multiplied by the branching ratio to be less than 77.9 pb at the 95% confidence level compared to the theoretically predicted value of 11.0 pb. This is the first search for Higgs bosons decaying to tau pairs at a hadron collider. CDF Collaboration, CLARK, Allan Geoffrey (Collab.), D'ONOFRIO, Monica (Collab.), WU, Xin (Collab.). Search for supersymmetric Higgs bosons in the di-tau decay mode in pp collisions at s√=1.8 TeV. Physical Review. D, 2005, vol. 72, no. 07, p. 072004 DOI : 10.1103/PhysRevD.72.072004

The studies discussed in this work are related to a scientific program that aims to reproduce astrophysical-plasmas in laboratory in order to better understand the nuclear processes involved in the stellar burning. An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ni, Fe and Co nanowires on laser energy absorption in the ns time domain has been carried out at the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS, Catania. Nanowires structures are tuned to increase the light absorption in the visible and infrared range due possibly to plasmonic excitation driven by the incoming photons. Different diagnostics techniques permit to monitor the plasma and to determine its reproducibility. Targets were then irradiated by Nd: YAG 2J, 6 ns infrared laser (lambda = 1064 nm) at different pumping energies. Some preliminary results will be illustrated.

An experimental campaign aiming to investigate the effects of innovative nanostructured targets based on Ag nanowires on laser energy absorption in the ns time domain has been carried out at the Laser Energy for Nuclear Science laboratory of INFN-LNS in Catania. The tested targets were realized at INFN-Bologna by anodizing aluminium sheets in order to obtain layers of porous Al2O3 of different thicknesses, on which nanowires of various metals are grown by electro-deposition with different heights. Targets were then irradiated by using a Nd:YAG laser at different pumping energies. Advanced diagnostic tools were used for characterizing the plasma plume and ion production. As compared with targets of pure Al, a huge enhancement (of almost two order of magnitude) of the X-ray flux emitted by the plasma has been observed when using the nanostructured targets, with a corresponding decrease of the "optical range" signal, pointing out that the energetic content of the laser produced plasma was remarkably increased. This analysis was furthermore confirmed from time-of-flight spectra.

We give results concerning the production of charm and beauty hadrons in 1rinteractions in thin metal targets at Js = 26 GeV. In order to select events containing heavy quarks we used the combined information of the CERN n' spectrometer and of a high-resolution silicon detector that allowed direct observation of the decay vertices of short-lived hadrons. In the 20% of our data sample analysed so far we have 81 events where the decay vertices of two charmed hadrons are detected. These double-charm events, for which the purity (85%) has been estimated directly from the data, have been used to study the azimuthal-angle correlation between pairs of charmed hadrons. Results are compared with QCD predictions. The same data sample is used to search for the production of beauty particles. Preliminary indications are that the number of events found is compatible with published measurements of the beauty cross-section.

Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to "screen" the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

The diffusion mechanism in magnetized plasmas is a largely debated issue. A short circuit model was proposed by Simon, assuming fluxes of lost particles along the axial (electrons) and radial (ions) directions which can be compensated, to preserve the quasi-neutrality, by currents flowing throughout the conducting plasma chamber walls. We hereby propose a new method to modify Simon's currents via electrons injected by a carbon nanotubes-based electron gun. We found this improves the source performances, increasing the output current for several charge states. The method is especially sensitive to the pumping frequency. Output currents for given charge states, at different auxiliary electron currents, will be reported in the paper and the influence of the frequency tuning on the compensation mechanism will be discussed.

We have performed a search for radiative b-hadron decays using events produced in pp̄ collisions at √ s = 1.8 TeV and collected by the Collider Detector at Fermilab. The decays we considered were B 0 d → K ∗0 (→ K−π+)γ, B 0 s → φ(→ K+K−)γ, Λb → Λ(→ pπ)γ, and their charge conjugates. Two independent methods to identify photons from such decays were employed. In the first method, the photon was detected in the electromagnetic calorimeter. In the second method, the photon was identified by an electron-positron pair produced through the external photon conversion before the tracking detector volume. By combining the two methods we obtain upper limits on the branching fractions for the B 0 d, B 0 s, and Λ 0 b radiative decays, which, at the 95% confidence level, are found to be B(B0d → K ∗0 γ) < 1.4 × 10−4, B(B0s → φγ) < 1.6 × 10−4, and B(Λb → Λγ) < 1.9 × 10−3. PACS numbers: 14.40.Nd, 14.20.Mr Typeset using REVTEX

The increase of electron density in ECR ion sources assures efficient ionization of very low-gas-pressure plasma. The purpose of this experiment was the creation of a carbon nanotubes based electron gun, in order to inject electrons in the plasma core and to follow how the charge state distribution and the X-ray spectra change. The use of carbon nanotubes leads to an increase of the plasma density and to a relevant reduction of the number of high energy electrons, which are detrimental for the reliability of the modern ECRIS.

1INFN, Sezione di Bologna, Viale B. Pichat 6/2, 40127 Bologna, Italy 2Dipartimento di Fisica, Università di Bologna, Viale B. Pichat 6/2, 40127 Bologna, Italy 3Istituto per la Microelettronica ed Microsistemi del CNR, Via Gobetti 101, 40129 Bologna, Italy 4INFN Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania, Italy 5CSFNSM, Viale A. Doria 6, 95125 Catania, Italy 6Università degli Studi di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l’Ingegneria, Viale A. Doria 6, 95125 Catania, Italy 7Università degli Studi di Catania, Dipartimento di Fisica e Astronomia via S. Sofia 64, 95123 Catania, Italy 8Università di Messina, Ctr.da Papardo-Sperone, 98100, Messina, Italy

Carbon nanotubes (CNTs), with their excellent electronic properties and extremely high aspect ratio, represent an ideal material for building electron sources based on field emission. Fowler-Nordheim equation describes quite successfully the field emission phenomenon, especially for single or isolated tips. However, some complications arise when populations of CNTs are considered, where collective effects and large variability in the emitters features influence the measured I V characteristics. In this work, the emission properties of multi-walled CNTs grown within ordered anodic alumina templates are investigated. These CNT matrices produce current densities up to some tens of mA/cm(2), and the field enhancement factor for collective emission sources can be estimated. Such material can be modelled as an ordered and uniform array of emitters and a simulation of the electrostatic field on the emission tips can be done in order to evaluate the field enhancement factor and its dependence on various geometries. This allows comparing predictions from simulation and experimental measurements, in a direct way. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Different electrochemical regimes and porous alumina were applied for template synthesis of cobalt nanowire ( nw ) arrays, revealing several peculiar cases. In contrast to quite uniform filling of sulfuric acid alumina templates by alternating current deposition, nonuniform growth of the Co nw tufts and mushrooms was obtained for the case of oxalic acid templates. We showed herein for the first time that such configurations arise from the spontaneous growth of cobalt nw groups evolving from the cobalt balls at the Al/alumina interface. Nevertheless, the uniform growth of densely packed cobalt nw arrays, up to tens of micrometers in length, was obtained via long-term direct current galvanostatic deposition at low current density using oxalic acid templates one-side coated by conducting layer. The unique point of this regime is the formation of hexagonal lattice Co nws with a preferred (100) growth direction.