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Now showing items 1 - 16 of 74

  • Preliminary results of a new boron coated neutron detector

    Gervino, G.   Balma, M.   Devona, D.   Lavagno, A.   Palmisano, C.   Zamprotta, L.   Scarfone, A.   Tintori, C.  

    The proliferation of neutron detection applications based upon 3He counter has triggered a critical shortage of 3He gas. Nowadays there is an increasing demand for alternative neutron detectors that can cover large solid angles, have low sensitivity to gamma background and low cost. We present a low cost neutron detector based upon 3 cm diameter, 150 cm long cylindrical metal tube coated on the inside with a thin layer of 10B-enriched boron carbide (10B4C) fulfilled by 1 atm nitrogen.
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  • Ultra-sensitive γ-ray spectroscopy set-up for investigating primordial lithium problem

    Gervino, G.   Gustavino, C.   Trezzi, D.   Aliotta, M.   Anders, M.   Boeltzig, A.   Bemmerer, D.   Best, A.   Broggini, C.   Bruno, C.   Caciolli, A.   Cavanna, F.   Corvisiero, P.   Davinson, T.   Depalo, R.   DiLeva, A.   Elekes, Z.   Ferraro, F.   Formicola, A.   Fül?p, Zs.   Guglielmetti, A.   Gyürky, Gy.   Imbriani, G.   Junker, M.   Menegazzo, R.   Prati, P.   Scott, D.A.   Straniero, O.   Szücs, T.  

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  • The bottleneck of CNO burning and the age of Globular Clusters

    Imbriani, G.   Costantini, H.   Formicola, A.   Bemmerer, D.   Bonetti, R.   Broggini, C.   Corvisiero, P.   Cruz, J.   Fülöp, Z.   Gervino, G.   Guglielmetti, A.   Gustavino, C.   Gyürky, G.   Jesus, A. P.   Junker, M.   Lemut, A.   Menegazzo, R.   Prati, P.   Roca, V.   Rolfs, C.   Romano, M.   Rossi Alvarez, C.   Schümann, F.   Somorjai, E.   Straniero, O.   Strieder, F.   Terrasi, F.   Trautvetter, H. P.   Vomiero, A.   Zavatarelli, S.  

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  • Characterization of CVD-diamonds for radiation detection

    Gervino, G.   Bizzaro, S.   Palmisano, C.   Periale, L.  

    We report the results of our investigations on high quality single crystal chemical vapor deposition (SC-CVD) diamonds to be used as ionizing radiation detectors. Recent progress in growth of synthetic diamonds of very high purity and high homogeneity has opened perspectives to a new type of UV photosensors in order to work with large volume two-phase liquid-Ar and/or liquid-Xe detectors, nowadays under design for next generation dark matter search. SC-CVD diamonds supplied by Brevetti Bizz firm of San Bonifacio (VR, Italy) were investigated and the results are presented and discussed. (C) 2012 Elsevier B.V. All rights reserved.
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  • Optimization of statistical methods for HpGe gamma-ray spectrometer used in wide count rate ranges

    Gervino, G.   Mana, G.   Palmisano, C.  

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  • Environmental radon monitoring: comparing drawbacks and performances of charcoal canisters, alpha-track and E-PERM detectors

    Gervino, G.   Bonetti, R.   Cigolini, C.   Marino, C.   Prati, P.   Pruiti, L.  

    Nowadays there are mainly three types of detectors available for measuring radon concentrations: charcoal canisters, alpha-tracks and E-PERMs. We carried out measurements with the three types of detectors and we tested their performances over a wide range of radon concentrations, temperatures and humidities. We compared the results obtained with the different detectors and we critically evaluated the results.
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  • Study of beam heating effect in a gas target through Rutherford scattering RID B-2262-2008 RID F-1078-2010

    Marta, M.   Confortola, F.   Bemmerer, D.   Boiano, C.   Bonetti, R.   Broggini, C.   Casanova, M.   Corvisiero, P.   Costantini, H.   Elekes, Z.   Formicola, A.   Fulop, Z.   Gervino, G.   Guglielmetti, A.   Gustavino, C.   Gyurky, G.   Imbriani, G.   Junker, M.   Lemut, A.   Limata, B.   Menegazzo, R.   Prati, P.   Roca, V.   Rolfs, C.   Romano, M.   Alvarez, C. Rossi   Somorjai, E.   Strieder, F.   Terrasi, F.   Trautvetter, H. P.  

    A systematic study of alpha-beam heating effect on a windowless gas target through Rutherford scattering is described. For such measurements, an ion implanted commercial silicon detector to reveal 100-250 keV alphas is used coupled with a low-noise home-made preamplifier. The results Oil density reduction of the gas in the target due to beam heating are discussed and their importance for high precision cross section measurements at very low energies are underlined. (c) 2006 Elsevier B.V. All rights reserved.
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  • Ground state capture in (14)N(p,gamma)(15)O studied above the 259 keV resonance at LUNA RID B-2262-2008 RID F-1078-2010 RID F-7567-2010

    Trautvetter, H. P.   Bemmerer, D.   Bonetti, R.   Broggini, C.   Caciolli, A.   Confortola, F.   Corvisiero, P.   Costantini, H.   Elekes, Z.   Formicola, A.   Fueloep, Zs   Gervino, G.   Guglielmetti, A.   Gyuerky, Gy   Gustavino, C.   Imbriani, G.   Junker, M.   Lemut, A.   Limata, B.   Marta, M.   Mazzocchi, C.   Menegazzo, R.   Prati, P.   Roca, V.   Rolfs, C.   Alvarez, C. Rossi   Somorjai, E.   Straniero, O.   Strieder, F.   Terrasi, F.   Vezzu, S.   Vomiero, A.  

    We report on a new measurement of (14)N(p,gamma)(15)O for the ground state capture transition at E(p) = 360, 380 and 400 keV, using the 400 kV LUNA accelerator. The true coincidence summing effect-the major source of error in the ground state capture determination-has been significantly reduced by using a Clover-type gamma detector.
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  • Phenomenological approach to baryon resonance damping in nuclei

    Alberico, W.M.   Gervino, G.   Lavagno, A.  

    We analyse the total photonuclear cross section in the energy range from 0.2 to 1.2 GeV, recently measured in Frascati on C, Be and U. By employing a simple resonance-hole model for the various baryonic resonances, which exist in the above range, we find that the experimental cross sections can be fairly well reproduced if one assumes that the nuclear medium strongly increases the width of all resonances above the Delta
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  • GRAAL: a polarized gamma-ray beam at ESRF

    Bocquet, J.P.   Ajaka, J.   Anghinolfi, M.   Bellini, V.   Berrier, G.   Calvat, P.   Capogni, M.   Casano, L.   Castoldi, M.   Corvisiero, P.   D'Angelo, A.   Didelez, J.P.   Di Salvo, R.   Djalali, C.   Duval, M.A.   Frascaria, R.   Gervino, G.   Ghio, F.   Girard, P.   Girolami, B.   Guinault, E.   Hourani, E.   Kuznetsov, V.   Lapik, A.   Levi Sandri, P.   Lo Nigro, S.   Moricciani, D.   Morlet, M.   Muccifora, V.   Nedorezov, V.   Perrin, C.   Rebreyend, D.   Renard, F.   Ricco, G.   Rigney, M.   Ripani, M.   Rosier, L.   Rossi, P.   Russew, T.   Sanzone, M.   Schaerf, C.   Scire, A.   Sperduto, M.L.   Sudov, A.   Taiuti, M.   Turinge, A.   Van de Wiele, J.   Vinciguerra, D.   Zucchiatti, A.  

    The GRAAL facility produces a highly polarized gamma-ray beam by Compton scattering of laser photons on the electrons of the European Synchrotron Radiation Facility (ESRF) at Grenoble. Preliminary results have been obtained with the LAGRANGE detector showing its excellent performances
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  • Revision of the (15)N(p, gamma)(16)O reaction rate and oxygen abundance in H-burning zones RID B-2262-2008

    Caciolli, A.   Mazzocchi, C.   Capogrosso, V.   Bemmerer, D.   Broggini, C.   Corvisiero, P.   Costantini, H.   Elekes, Z.   Formicola, A.   Fueloep, Zs.   Gervino, G.   Guglielmetti, A.   Gustavino, C.   Gyuerky, Gy.   Imbriani, G.   Junker, M.   Lemut, A.   Marta, M.   Menegazzo, R.   Palmerini, S.   Prati, P.   Roca, V.   Rolfs, C.   Alvarez, C. Rossi   Somorjai, E.   Straniero, O.   Strieder, F.   Terrasi, F.   Trautvetter, H. P.   Vomiero, A.  

    Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T similar or equal to 30 x 10(6) K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims. The activation of this cycle depends on the rate of the (15)N(p, gamma)(16)O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods. We present a new measurement of the (15)N(p, gamma)(16)O reaction performed at LUNA covering for the first time the center of mass energy range 70-370 keV, which corresponds to stellar temperatures between 65 x 10(6) K and 780 x 10(6) K. This range includes the (15)N(p, gamma)(16)O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results. With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level.
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  • Vertex identification of events in photonuclear reactions by cylindrical multiwire proportional chambers RID B-7657-2011 RID B-1239-2012

    Mandaglio, G.   Manganaro, M.   Giardina, G.   Bellini, V.   Giusa, A.   Mammoliti, F.   Randieri, C.   Russo, G.   Sperduto, M. L.   Sutera, C.   Casano, L.   D'Angelo, A.   Di Salvo, R.   Fantini, A.   Franco, D.   Moricciani, D.   Schaerf, C.   Vegna, V.   Sandri, P. Levi   Girolami, B.   Ghio, F.   Gervino, G.   Bocquet, J. P.   Lleres, A.   Rebreyend, D.   Renard, F.   Ignatov, A. S.   Lapik, A. M.   Mushkarenkov, A. N.   Nedorezov, V. G.   Rudnev, N. V.   Turinge, A. A.  

    In the framework of investigation of meson photo-production on proton and neutron in a deuterium target at the GRAAL experiment, we present a method to identify the vertex of interaction when in reaction products there are at least two charged particles, by the information provided by the cylindrical multiwire proportional chambers. By this device, we are able to obtain the direction of charged particles that leave the target after a photo-production reaction. For each charged particle, the device provides the coordinates of two points in the laboratory reference system, and the z-axis represents the beam direction. We calculate the trajectory of each charged particle and its cross point, representing the vertex of the reaction.
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  • A BGO spectrometer for 200-1500 MeV photons

    Anghinolfi, M.   Castoldi, M.   Corvisiero, P.   Gervino, G.   Mazzaschi, L.   Mokeev, V.   Ricco, G.   Ripani, M.   Sanzone, M.   Taiuti, M.   Zucchiatti, A.   Bianchi, N.   De Sanctis, E.   Ebolese, A.   Fantoni, A.   Levi Sandri, P.   Lucherini, V.   Muccifora, V.   Polli, E.   Reolon, A.R.   Rossi, P.  

    A BGO spectrometer used at Frascati both as a monitor for a tagged-photon beam and as a photon spectrometer in a total photonuclear absorption experiment is described. Measured characteristics of the detector (response function, energy resolution, and tagged-bremsstrahlung spectra of energy up to 1.5 GeV) are shown, and compared to a Monte Carlo simulation
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  • [AIP FRONTIERS IN NUCLEAR STRUCTURE, ASTROPHYSICS, AND REACTIONS - FINUSTAR - Isle of Kos (Greece) (12-17 September 2005)] AIP Conference Proceedings - Nonextensive statistical effects on nuclear astrophysics

    Gervino, G.  

    Density and temperature conditions in many stellar core (like the solar core) imply the presence of nonideal plasma effects with memory and long-range interactions between particles. This aspect suggests the possibility that the stellar core could not be in a global thermodynamical equilibrium but satisfies the conditions of a metastable state with a stationary (nonextensive) power law distribution function among ions. The order of magnitude of the deviation from the standard Maxwell-Boltzmann distribution can be derived microscopically by considering the presence of random electrical microfields in the stellar plasma. We show that such a nonextensive statistical effect can be very relevant in many nuclear astrophysical problems
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  • The cross section of 3He( 3He,2p) 4He measured at solar energies

    Junker, M.   Arpesella, C.   Bellotti, E.   Broggini, C.   Corvisiero, P.   D'Alessandro, A.   Fiorentini, G.   Fubini, A.   Gervino, G.   Greife, U.   Gustavino, C.   Lambert, J.   Prati, P.   Rodney, W.S.   Rolfs, C.   Trautvetter, H.P.   Zavatarelli, S.  

    We report on the status of the 3He( 3He,2p) 4He experiment at the underground accelerator facility LUNA (Gran Sasso). The lowest projectile energies for the measured cross section correspond already to energies below the center of the solar Gamow peak (E 0=22 keV). The data provide no evidence for the existence of a hypothetical resonance in the energy range investigated. Although no extrapolation is needed anymore (except for energies at the low-energy tail of the Gamow peak), the data must be corrected for the effects of electron screening, clearly observed the first time for the 3He( 3He,2p) 4He reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted S(0) value for bare nuclides (=5.40 MeVb)
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  • Thermodynamic instabilities in high energy heavy-ion collisions

    Lavagno, A.   Pigato, D.   Gervino, G.  

    One of the very interesting aspects of high energy heavy-ion collisions experiments is a detailed study of the thermodynamical properties of strongly interacting nuclear matter away from the nuclear ground state. In this direction, many efforts were focused on searching for possible phase transitions in such collisions. We investigate thermodynamic instabilities in a hot and dense nuclear medium where a phase transition from nucleonic matter to resonance-dominated Delta-matter can take place. Such a phase transition can be characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the strangeness concentration) in asymmetric nuclear matter. In analogy with the liquid-gas nuclear phase transition, hadronic phases with different values of antibaryon-baryon ratios and strangeness content may coexist. Such a physical regime could be, in principle, investigated in the future high-energy compressed nuclear matter experiments which will make it possible to create compressed baryonic matter with a high net baryon density.
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