Papers by Gianpiero Gervino
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1994
A compact high-current 50 kV ion accelerator facility including a windowless gas target system, a... more A compact high-current 50 kV ion accelerator facility including a windowless gas target system, a beam calorimeter, and detector telescopes in close geometry has been built and tested. The data acquisition and analysis involved a multiparameter system and a Monte Carlo program. The LUNA facility, presently installed at the Gran Sasso underground laboratory, is a pilot project focused initially on
Journal of Physics G: Nuclear and Particle Physics, 2005
Hashing is a fundamental tool in digital forensic analysis used both to ensure data integrity and... more Hashing is a fundamental tool in digital forensic analysis used both to ensure data integrity and to efficiently identify known data objects. However, despite many years of practice, its basic use has advanced little. Our objective is to leverage advanced hashing techniques in order to improve the efficiency and scalability of digital forensic analysis. Specifically, we explore the use of Bloom filters as a means to efficiently aggregate and search hashing information. In this paper, we present md5bloomdan actual Bloom filter manipulation tool that can be incorporated into forensic practice, along with example uses and experimental results. We also provide a basic theoretical foundation, which quantifies the error rates associated with the various Bloom filter uses along with a simulation-based verification. We provide a probabilistic framework that allows the interpretation of direct, bitwise comparison of Bloom filters to infer similarity and abnormality. Using the similarity interpretation, it is possible to efficiently identify versions of a known object, whereas the notion of abnormality could aid in identifying tampered hash sets.
The European Physical Journal B - Condensed Matter and Complex Systems, 2006
In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the en... more In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the entropy generation. In the thermoeconomic optimization of an irreversible Stirling heat pump cycle the F function has been introduced to evaluate the optimum for the higher and lower sources temperature ratio in the cycle: this ratio represents the value which optimizes the cycle itself. The variation of the function F is proportional to the variation of the entropy generation, the maxima and minima of F has been evaluated in a previous paper without giving the physical foundation of the method. We investigate the groundwork of this approach: to study the upper and lower limits of F function allows to determine the cycle stability and the optimization conditions. The optimization consists in the best COP at the least cost. The principle of maximum variation for the entropy generation becomes the analytic foundation of the optimization method in the thermoeconomic analysis for an irreversible Stirling heat pump cycle.
The European Physical Journal A, 2007
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Universe
We present NEAR, a new experimental area at the CERN-n_TOF facility and a possible setup for cros... more We present NEAR, a new experimental area at the CERN-n_TOF facility and a possible setup for cross section measurements of interest to nuclear astrophysics. This was recently realized with the aim of performing spectral-averaged neutron-capture cross section measurements by means of the activation technique. The recently commissioned NEAR station at n_TOF is now ready for the physics program, which includes a preliminary benchmark of the proposed idea. Based on the results obtained by dedicated Monte Carlo simulations and calculation, a suitable filtering of the neutron beam is expected to enable measurements of Maxwellian Averaged Cross Section (MACS) at different temperatures. To validate the feasibility of these studies we plan to start the measurement campaign by irradiating several isotopes whose MACS at different temperatures have recently been or are planned to be determined with high accuracy at n_TOF, as a function of energy in the two time-of-flight measurement stations. F...
Physical Review C, 2015
We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron ... more We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (Eγ = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the threepion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement and provide important constraints for the determination of resonant state contributions to the ω production mechanism. First experimental results on the deuteron allow the extraction of the Σ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target.
Physical Review C, 2015
First measurement of the beam asymmetry for Compton scattering off the proton in the energy range... more First measurement of the beam asymmetry for Compton scattering off the proton in the energy range E γ = 0.85-1.25 GeV is presented. The data reveal two narrow structures at E γ = 1.036 and E γ = 1.119 GeV. They may signal narrow resonances with masses near 1.68 and 1.72 GeV, or they may be generated by the subthreshold K and ωp production. Their decisive identification requires additional theoretical and experimental efforts.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006
A systematic study of a-beam heating effect on a windowless gas target through Rutherford scatter... more A systematic study of a-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 on 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.
Nstar 2002: Proceedings of the Workshop on the Physics of Excited Nucleons, 2003
The double pi0 and omega-meson photoproduction have been measured at GRAAL. The total and differe... more The double pi0 and omega-meson photoproduction have been measured at GRAAL. The total and differential cross sections and the beam asymmetry were deduced. In the double pi0 channel, the total cross section is dominated by two peaks at 0.7 and 1.1 GeV of beam energy, the second one having been seen for the first time. The interpretation of the double
Physical review letters, Jan 25, 2014
Recent observations of (6)Li in metal poor stars suggest a large production of this isotope durin... more Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The mu...
Physics Letters B, 2004
We report on a new measurement of the 14 N(p, γ) 15 O capture cross section at Ep = 140 to 400 ke... more We report on a new measurement of the 14 N(p, γ) 15 O capture cross section at Ep = 140 to 400 keV using the 400 kV LUNA accelerator facility at the Laboratori Nazionali del Gran Sasso (LNGS). The uncertainties have been reduced with respect to previous measurements and their analysis. We have analyzed the data using the R-matrix method and we find that the ground state transition accounts for about 15% of the total S-factor. The main contribution to the S-factor is given by the transition to the 6.79 MeV state. We find a total S(0) = 1.7 ± 0.2 keV b, in agreement with recent extrapolations. The result has important consequences for the solar neutrino spectrum as well as for the age of globular clusters.
Physical Review C, 1998
We report on the results of the 3 He(3 He,2p) 4 He experiment at the underground accelerator faci... more We report on the results of the 3 He(3 He,2p) 4 He experiment at the underground accelerator facility LUNA (Gran Sasso). For the first time the lowest projectile energies utilized for the cross section measurement correspond 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 3 He(3 He,2p) 4 He reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted S b (E 0) value for bare nuclides (=5.40 MeV b).
Physical Review C, 2008
We present the first measurement of the beam asymmetry in η photoproduction on the neutron in the... more We present the first measurement of the beam asymmetry in η photoproduction on the neutron in the photon energy range from threshold to 1.5 GeV. Data have been collected by using the tagged and linearly polarized photon beam and the large solid angle apparatus of the GRAAL facility. Neutron data have been selected among η photoproduction events on the deuteron in the quasi-free kinematics approximation. Proton data, extracted in the same way, are within errors identical to those previously obtained on free protons at the GRAAL facility, except for a few points falling in certain energy bins. This difference is, however, well understood in terms of the Fermi motion of the nucleons in the deuteron. We take the consistency of free and quasi-free proton data as an indication that nuclear effects are negligible also for neutron data. The ETAMAID model, in which a strong coupling of the D 15 (1675) resonance to the η-neutron channel is introduced, can explain the proton data very well, but it cannot describe the beam asymmetry for the neutron.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1994
A compact high-current 50 kV ion accelerator facility including a windowless gas target system, a... more A compact high-current 50 kV ion accelerator facility including a windowless gas target system, a beam calorimeter, and detector telescopes in close geometry has been built and tested. The data acquisition and analysis involved a multiparameter system and a Monte Carlo program. The LUNA facility, presently installed at the Gran Sasso underground laboratory, is a pilot project focused initially on
Journal of Physics G: Nuclear and Particle Physics, 2005
Hashing is a fundamental tool in digital forensic analysis used both to ensure data integrity and... more Hashing is a fundamental tool in digital forensic analysis used both to ensure data integrity and to efficiently identify known data objects. However, despite many years of practice, its basic use has advanced little. Our objective is to leverage advanced hashing techniques in order to improve the efficiency and scalability of digital forensic analysis. Specifically, we explore the use of Bloom filters as a means to efficiently aggregate and search hashing information. In this paper, we present md5bloomdan actual Bloom filter manipulation tool that can be incorporated into forensic practice, along with example uses and experimental results. We also provide a basic theoretical foundation, which quantifies the error rates associated with the various Bloom filter uses along with a simulation-based verification. We provide a probabilistic framework that allows the interpretation of direct, bitwise comparison of Bloom filters to infer similarity and abnormality. Using the similarity interpretation, it is possible to efficiently identify versions of a known object, whereas the notion of abnormality could aid in identifying tampered hash sets.
The European Physical Journal B - Condensed Matter and Complex Systems, 2006
In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the en... more In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the entropy generation. In the thermoeconomic optimization of an irreversible Stirling heat pump cycle the F function has been introduced to evaluate the optimum for the higher and lower sources temperature ratio in the cycle: this ratio represents the value which optimizes the cycle itself. The variation of the function F is proportional to the variation of the entropy generation, the maxima and minima of F has been evaluated in a previous paper without giving the physical foundation of the method. We investigate the groundwork of this approach: to study the upper and lower limits of F function allows to determine the cycle stability and the optimization conditions. The optimization consists in the best COP at the least cost. The principle of maximum variation for the entropy generation becomes the analytic foundation of the optimization method in the thermoeconomic analysis for an irreversible Stirling heat pump cycle.
The European Physical Journal A, 2007
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The European Physical Journal A, 2009
The double polarization (beam-recoil) observables Ox and Oz have been measured for the reaction γ... more The double polarization (beam-recoil) observables Ox and Oz have been measured for the reaction γp → K + Λ from threshold production to Eγ ∼ 1500 MeV. The data were obtained with the linearly polarized beam of the GRAAL facility. Values for the target asymmetry T could also be extracted despite the use of an unpolarized target. Analyses of our results by two isobar models tend to confirm the necessity to include new or poorly known resonances in the 1900 MeV mass region.
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Papers by Gianpiero Gervino