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Experiments of nuclear physics have been carried out at the Bern medical cyclotron, in which a beam line dedicated to research activities is available. Our main goal is to upgrade this facility as a well-characterized neutron source for studies of radiation hardness and for tests of new neutron detectors. To achieve this result, preliminary measurements have been carried out among which the measurement of the incident proton energy by means of a method based on Rutherford backscattering spectroscopy. The analysis of the energy spectrum corresponding to protons elastically and inelastically backscattered by the carbon target allowed the precise identification of the excited states of 12C, including the Hoyle state. These results confirmed the Bern medical cyclotron as a reliable facility to perform research activities in the field of fundamental nuclear physics as well as of applied physics.

Recent results in the field of film dosimetry demonstrated that the Green–Saunders equation, a solution of the logistic equation describing phenomena of kinetics of chemical reactions, is the absolute calibration function for all radiochromic film types. Taking advantage of the new opto-electronics-based radiochromic film reading method, which allows real-time measurements of the spectral response of radiochromic films, we confirm that the film darkening is ruled by the Green–Saunders equation independently both from the reading instrument or the choice of the observable used for the calibration. In order to demonstrate it, we exposed an XR-QA2 Gafchromic film to 90Sr/90Y beta rays up to 1400 mGy. Film spectra are recorded in real-time. The calibration is performed by means of two analytic methods: evaluation of the integral under the curves from 500 nm to 645 nm and evaluation of the intensity at 570, 600 and 643 nm. Experimental data fit to the Green–Saunders equation for both methods.

In this work, we report on a novel approach for measuring the dose absorbed by the EBT3 Gafchromic™ films exposed to 1 MeV electron beam and 250 kV X-rays in the range 0.5–100 Gy. Although EBT3 is specifically designed to obtain best performance for applications where the maximum dose is less than 10 Gy, there are certain clinical applications requiring dose ranges well above this value. In order to cover wider dose ranges, further models characterized by a thinner sensitive layer and/or different chemical composition have been released. Another method exploiting the three-channel flatbed scanner to delay the saturation point of EBT3 has been also reported. The technique proposed here, aimed at extending the sensitivity of the EBT3 film to high doses up to 100 Gy while ensuring a low dose uncertainty, is based on a broadband analysis of the absorption spectrum of the film in response to irradiation. By combining a wavelength-based approach with the monitoring of two characteristic peaks of the EBT3 absorption spectrum, we demonstrated the capability of measuring the dose in the range 0.5–100 Gy with an experimental uncertainty below 4% for doses lower than 5.52 Gy and below 2% for higher dose levels. Finally, through a dynamic fitting procedure integrating the two aforesaid approaches, a total uncertainty lower than 4%, including both the experimental and fitting errors, was achieved in the whole range 0.5–100 Gy. These results are promising in view of a potential application of this technique in the field of clinical dosimetry at high dose levels.

Single-photon avalanche diodes (SPADs) in the CMOS technology are very attractive solution for photon detection due to the excellent timing resolution achievable. Unfortunately, such devices suffer from large values of the dark count (DC) pedestals. In this paper, we analyzed a test chip containing SPADs with different layouts, implemented in the 150-nm CMOS technology. The behavior of such devices has been investigated after proton irradiation. It is observed that, after irradiation, the DC rate switches between two or more discrete levels, phenomenon known as random telegraph signal (RTS). The effect is related to the density and distribution of defects in the semiconductor lattice. RTS characteristics have been studied as the function of both temperature and bias voltage. Discussion of results and main hypotheses on defect types responsible for RTS are reported.

Selected experiments in fundamental physics have been proposed for many years at the Tandem Accelerator of the University of Napoli 'Federico II's Department of Physics as a part of a one-semester laboratory course for graduate students. The aim of this paper is to highlight the educational value of the experimental realization of the nuclear reaction 19F(p,α)16O. With the purpose of verifying the mass–energy equivalence principle, different aspects of both classical and modern physics can be investigated, e.g. conservation laws, atomic models, nuclear physics applications to compositional analysis, nuclear cross-section, Q-value and nuclear spectroscopic analysis.

A unique calibration equation for all radiochromic film types is proposed. The determination of this equation comes from an analogy that the authors made between the radiochromic and photographic processes. Photography dynamics is ruled by a differential equation, the logistic equation, describing phenomena of growth versus competition. A solution of the logistic equation is the Green-Saunders equation which was used for the first time by the same authors in a previous referred work for the calibration of a set of EBT3 Gafchromic films. Since this equation has a fundamental physical interpretation, the fitting parameters also represent important physical quantities and two of them in particular fix the film dynamics; one being the contrast and the other the abscissa of the inflection point of the sensitometric curve. In order to show the validity of this approach for more than one radiochromic film type, two sets of radiochromic films, the B3 and HD-V2 Gafchromic films were exposed to several known doses and the Green-Saunders equation was found to perfectly fit the experimental data. A comparison with the same procedure used for EBT3 Gafchromic films is proposed. The findings of this work are an important step forward in the understanding of an interesting and widely used dosimetry technique.

The characteristics of radiochromic films such as the direct visualization of radiation field, ease of use and data analysis are suited for the dosimetry monitoring in tests of radiation hardness space applications. In particular, in this work, in order to study the dependence of radiation type, energy and dose rate, as well as the dynamic range of EBT3 Gafchromic films, a set of films was exposed to radiation sources used in total ionizing dose (60Co gamma- and 90Sr/90Y beta-rays). The results have been found to be particularly suited for the employment of this kind of films in radiation hardness assurance tests.

Neutron beams have been produced at Laboratory of High Energy Physics (LHEP) of University of Bern. LEHP is equipped with an 18 MeV cyclotron with an external beam line. Simulations, analytical calculations and kinematics studies have been carried out, in order to produce several neutron beam configurations with characteristics suited for specific applications. Furthermore, a procedure for energy modulation has been developed to match the fixed cyclotron energy to the needed requirements. The technique described in this work is of general application and can be applied to more intense beams up to 1010 pps.

For the study of astrophysically relevant capture reactions in the underground laboratory LUNA a newsetup of high sensitivity has been implemented. The setup includes a windowless gas target, a 4p BGO summing crystal, and beam calorimeters. The setup has been recently used to measure the d(p,g) 3 He cross-section for the first time within its solar Gamowpeak, i.e. dow n to 2.5 keV c.m. energy. The features of the optimized setup are described. r 2002 Elsevier Science B.V. All rights reserved.

The VSiPMT (Vacuum Silicon Photomultiplier Tube) is an innovative design for a revolutionary hybrid photodetector. The idea consists in replacing the classic dynode chain of a classic PMT with a SiPM. This new device aims at extending SiPM technology to large detection volumes. In this configuration, we match the large sensitive area of a photocathode with the performance of SiPM technology, which thererefore acts like an electron detector and current amplifier. The excellent photon counting capability, fast response, low power consumption and great stability are among the most attractive features of the VSiPMT. Hamamatsu realized two VSiPMT industrial prototypes with a photocathode of 3 mm diameter. In this work we present the progresses on the realization of a 1-inch prototype based on CsI photocathode and the preliminary tests we are performing on it.

Beyond their important economic role in commercial communications, satellites in general are critical infrastructure because of the services they provide. In addition to satellites providing information which facilitates a better understanding of the space environment and improved performance of physics experiments, satellite observations are also used to actively monitor weather, geological processes, agricultural development and the evolution of natural and man-made hazards. Defence agencies depend on satellite services for communication in remote locations, as well as for reconnaissance and intelligence. Both commercial and government users rely on communication satellites to provide communication in the event of a disaster that damages ground-based communication systems, provide news, education and entertainment to remote areas and connect global businesses. The space radiation environment is an hazard to most satellite missions and can lead to extremely difficult operating conditions for all of the equipment travelling in space. Here, we first provide an overview of the main components of space radiation environment, followed by a description of the basic mechanism of the interaction of radiation with matter. This is followed by an introduction to the space radiation hardness assurance problem and the main effects of natural radiation to the microelectronics (total ionizing dose, displacement damage and the single-event effect and a description of how different effects occurring in the space can be tested in on-ground experiments by using particle accelerators and radiation sources. We also discuss standards and the recommended procedures to obtain reliable results.

The absolute cross section σ ( E ) for the radiative capture reaction 7 Be(p, γ ) 8 B at the center-of-mass energies E =0.32 to 2.61 MeV has been measured using a 7 Be target deposited on a Cu backing and observing the β -delayed α -particles from 8 B. The backing causes a loss of less than 1% of the 8 B residual nuclides. The resulting astrophysical S ( E ) factor at zero energy, S (0)=18.4±1.6 eV b, is consistent only with a restricted data set from previous work.

An excitation function of the ground-state gamma (0)-ray capture transition in C-12(alpha, gamma)O-16 at theta (gamma) = 90 degrees was obtained in far geometry using six Ge detectors, where the study of the reaction was initiated in inverse kinematics involving a windowless gas target. The detectors observed predominantly the El capture amplitude. The data at E = 1.32 to 2.99 MeV lead to an extrapolated astrophysical S factor S-E1(E-0) = 90 +/- 15 keV b at E-0 = 0.3 MeV (for the case of constructive interference between the two lowest E1 sources), in good agreement with previous works. However, a novel Monte Carlo approach in the data extrapolation reveals systematic differences between the various data sets such that a combined analysis of all available data sets could produce a biased estimate of the S-E1(E-0) value. As a consequence, the case of destructive interference between the two lowest E1 sources with S-E1(E-0) = 8 +/- 3 keV b cannot be ruled out rigorously.

The El amplitude of the transition to the ground state in the C-12(alpha, gamma)O-16 capture reaction was measured in the energy range E-cm=1.3 to 3.0 MeV using an intense C-12 beam in combination with a windowless He-4 gas target and an array of six 70% HPGe detectors. The detectors were placed in a ring-shaped geometry around the target at a distance of 17 cm on a plane perpendicular to the beam axis. A target length of 5.3 cm was defined by a 12.5 cm thick lead shielding. Passive and active shielding was used to achieve the necessary suppression of the beam induced and cosmic background. The results of this measurement and their extrapolation to the relevant energy during the helium burning phase in massive stars are reported.

For improved measurements of the key astrophysical reaction C-12(alpha, gamma)O-16 in inverted kinematics, a recoil separator ERNA is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the O-16 recoils with about 50% efficiency. Calculations of the ion beam optics including all filtering and focusing elements of ERNA are presented. Since the C-12 projectiles and the O-16 recoils have essentially the same momentum, and since the C-12 ion beam emerging from the accelerator passes through a momentum filter (analysing magnet), the C-12 ion beam must be as free as possible from O-16 contamination for ERNA to succeed. In the present work, the O-16 contamination was reduced from a level of 1 x 10(-11) to a level below 2 x 10(-29) by the installation of Wien filters both before and after the analysing magnet. The measurement of these and other beam specifications involved other parts of the final ERNA layout - sequentially a Wien filter, a 60 degrees dipole magnet, another Wien filter, and a Delta E-E telescope. The setup led to a measured suppression factor of 5 x 10(-18) for the C-12 ion beam. The experiments also indicate that an almost free choice of the charge state for the O-16 recoils is possible in the separator.

The energy spectra of the γ-rays emitted in the 35Cl + 92Mo reaction at incident energy E = 260 MeV were measured in coincidence with the ejectiles produced in dissipative reaction events. The cumulative energy spectrum of the γ-rays coming from the decay of the ejectiles was calculated within the statistical model and its comparison to the experimental spectrum evidences an excess in the data for Eγ = 8 to 12 MeV. Such an excess, fitted with a Lorentz curve, is attributed to the preequilibrium GDR γ-decay of the intermediate dinuclear system. The centroid energy of the Lorentz curve corresponds to a dipole oscillation along the symmetry axis of the system and its width is found to be comparable to that of the ground state GDR low energy component of the deformed dinucleus. The small quantal dispersion Δl = (10.3 ± 0.1)ħ of the entrance channel angular momentum, determined by analysing the dissipative fragment angular distribution in the framework of the Strutinsky model, is suggested to limit the broadening of the preequilibrium GDR width.

The recoil separator ERNA (European Recoil Separator for Nuclear Astrophysics) for improved measurements of the astrophysical key reaction C-12(alpha, gamma)O-16 is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the O-16 recoils. The total detection efficiency of about 50 % allows direct measurements in a much wider energy range than previously accessible. In addition this technique allows improved measurements not hampered by cosmic background problems when compared to gamma -ray detection.

The absolute cross section sigma(E) of the radiative capture reaction p(Be-7,gamma)B-8 at the center-of mass energy E = 992 keV has been measured using a radioactive 7Be ion beam and a windowless gas target system filled with H-2 gas. The B-8 residual nuclides were detected with a recoil separator consisting of momentum and velocity filters and a BE E detector telescope. The B-8 yield was observed concurrently with the Be-7+p elastic scattering yield, relating sigma(E) to the Rutherford scattering cross section. The resulting value, sigma(E) = 0.41+/-0.11 mu b, leads to an S(E) factor at zero energy of S(0) = 16+/-4 eV b, in fair agreement with recommended values.

The composition of particulate matter in the atmosphere of four major Italian towns (Florence, Genoa, Milan and Naples) has been studied with the extensive application of IBA techniques. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which provide the separation of the particulate matter in two fractions. The concentrations in air of about 20 elements, and the total particulate mass, have been extracted in the PM2.5 and PM10 fractions with hourly resolution by PIXE, PIGE and optical analyses of about 2700 samples. IBA analyses have been performed at the 3 MeV external proton beam of the INFN accelerator facility at the University of Florence.

Radiochromic films are a commercial product available in a large number of different types. They can be used in a wide range of doses and fluence for different radiation types. The application in different fields such as photon and ion radiotherapy, industrial irradiations for modification of materials, sterilization and radiation hardness, makes very interesting to study the response of the films to more radiation types and energies. The aim of this work is to define the characteristics and dynamic range of EBT3 Gafchromic films for some specific applications. To this end the behaviour of EBT3 Gafchromic films has been studied in depth by comparing the films response to different radiation types. In particular, this work has been carried out to establish a useful procedure to monitor the electronic device's irradiations for radiation hardness applications. The dynamic range of EBT3 films has been found to be compatible with the typically demanded fluences and the calibration has been found to be absolute, namely independent of the incident radiation type. The easy handling, the possibility of replacement of the films and high resolution power allow the monitoring of irradiations with a high range of doses.

We worked on the R&D of an innovative photodetector, the Vacuum Silicon Photomultiplier Tube (VSiPMT). The VSiPMT is composed by a photocathode and a solid state amplification stage. A semi-transparent conductive layer is necessary to supply voltage and to obtain a highly efficient CsI photocathode. Since the literature is poor on this topic we performed a systematic and detailed study of a set of semi-transparent conductive layers, made by different material and thickness. A CsI photocathode was evaporated on each sample. The impact of the semi-transparent conductive layer on the quantum efficiency of the photocathode is discussed.

The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design for a revolutionary hybrid photodetector. The idea, born with the purpose to use a SiPM for large detection volumes, consists in replacing the classical dynode chain with a SiPM. In this configuration, we match the large sensitive area of a photocathode with the performances of the SiPM technology, which therefore acts like an electron detector and so like a current amplifier. The excellent photon counting capability, fast response, low power consumption and great stability are among the most attractive features of the VSiPMT. In order to realize such a device we first studied the feasibility of this detector both from theoretical and experimental point of view, by implementing a Geant4-based simulation and studying the response of a special non-windowed MPPC by Hamamatsu with an electron beam. Thanks to this result Hamamatsu realized two VSiPMT industrial prototypes with a photocathode of 3mm diameter. We present the progress on the realization of a 1-inch prototype and the preliminary tests we are performing on it.

The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design we proposed for a revolutionary photon detector. The main idea is to replace the classical dynode chain of a PMT with a SiPM (G-APD), the latter acting as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performance of the SiPM technology. The VSiPMT has many attractive features. In particular, a low power consumption and an excellent photon counting capability. To prove the feasibility of the idea we first tested the performance of a special non-windowed SiPM by Hamamatsu (MPPC) as electron detector and current amplifier. Thanks to this result Hamamatsu realized two VSiPMT industrial prototypes. In this work, we present the results of a full characterization of the VSiPMT prototype.

We give the LUNA results on the $\ensuremath{\sigma}(E)$ cross section measurement of a key reaction of the proton-proton chain strongly affecting the calculated neutrino luminosity from the Sun: ${}^{3}\mathrm{He}{(}^{3}\mathrm{He},2p{)}^{4}\mathrm{He}$. Because of the cosmic ray suppression provided by the Gran Sasso underground laboratory, it has been possible to measure $\ensuremath{\sigma}(E)$ throughout the energy range in which this reaction occurs in the Sun, i.e., down to $16.5\mathrm{keV}$ center of mass energy. The data clearly show the cross section increase due to the electron screening effect but they do not exhibit any evidence for a narrow resonance suggested to explain the ${}^{8}\mathrm{B}$ and ${}^{7}\mathrm{Be}$ solar neutrino flux reduction.

Intermediate mass fragments (IMF) and light particles emitted from the Ni-58 + Ni-58 reaction at a beam energy of 375 MeV have been studied. The fragments and light particles were measured in coincidence with 4 pi gamma-ray spectrometer. The Z=6 (C) kinetic energy spectra and the distribution of the final nuclei in coincidence with the emitted C are well described by Hauser-Feshbach calculations extended to many channels. A detailed study of C-Psi and 3 alpha-gamma correlations indicate a strong selectivity of the IMF decay. Our results indicate that the IMF can populate nuclei that are not accessible via multiple light particle (Z

The absolute cross section σ of the d(7Li, p)8Li reaction near the Ecm= 0.61 MeV resonance has been measured using a 7Li ion beam and a windowless gas target system filled with D2 gas. The proton yield of the reaction and the β-delayed α-activity of the residual nuclides 8Li were observed both concurrently with the elastic scattering yield, relating σ to the Rutherford scattering cross section σR. The resulting values, σ (from p) = 143.6 ± 8.9 mb and σ (from 8Li) = 151 ± 20 mb, lead to a weighted mean value of σ = 153 ± 6 mb (χ2 = 2.26) including all available values and σ = 146 ± 5 mb (χ2 = 0.05) removing some values from the data set. The consequences for the expected flux of high-energy solar neutrinos are discussed.

We will discuss new experimental data concerning the elastic resonant scattering of α- particles on 9Be nuclei at bombarding energies from 3.5 MeV up to 9.9 MeV. Several excitation functions have been obtained at different polar angles, mainly in the backward hemisphere in the centre of mass frame. Excitation functions show various anomalies that can be linked to the presence of various excited states in the 13C compound nucleus. In the literature, some of these states have been proposed to belong to rotational bands built on deformed a-cluster excited state. Unfortunately, up to date the spin-parity assignment of many of these states is doubtful. The set of excitation functions we obtained from the present experiment can contribute to improve spectroscopy of highling excited states of 13C.

A recoil separator in combination with a windowless gas target has been designed for the measurement of the radiative capture reaction p(7Be, γ)8B. The separator consists of momentum and velocity filters and a ΔE−E detector telescope. The setup was tested quantitatively using the p(12C, γ)13N reaction at the effective energy Ecm = 841 keV. Projectile fluxes were measured directly with Faraday cups and indirectly with elastic backscattering into Si detectors, while the 13N recoil flux was measured directly with the ΔE−E telescope. A suppression of the 12C beam particles by a factor 2 × 10−10 was observed when the system was tuned for the recoil 13N's. Special emphasis was given to the charge state probabilities of the 13N recoils. Possible improvements of the system for the measurement of other capture reactions are discussed.

The chronology of the most significant eruptions at the island of Ischia in the last 5000 years has been studied by means of Accelerator Mass Spectrometry to obtain 14 C data. The results are in good agreement with stratigraphical and archeological constraints. This allows interpretation of the measured dates as ages of the eruptions which produced the deposits overlying or incorporating the sampled paleosols and charcoal fragments, respectively. These ages define the timing of volcanism in the last 5000 years, suggesting that the recent volcanic activity at Ischia is characterized by periods of very intense volcanism alternating to periods of quiescence. This timing of the volcanism is correlated with the behaviour of the magmatic system and dynamics of resurgence of the Mt. Epomeo block.

The absolute cross section σ of the d(7Li, p)8Li reaction near the Ecm= 0.61 MeV resonance has been measured using a 7Li ion beam and a windowless gas target system filled with D2 gas. The proton yield of the reaction and the β-delayed α-activity of the residual nuclides 8Li were observed both concurrently with the elastic scattering yield, relating σ to the Rutherford scattering cross section σR. The resulting values, σ (from p) = 143.6 ± 8.9 mb and σ (from 8Li) = 151 ± 20 mb, lead to a weighted mean value of σ = 153 ± 6 mb (χ2 = 2.26) including all available values and σ = 146 ± 5 mb (χ2 = 0.05) removing some values from the data set. The consequences for the expected flux of high-energy solar neutrinos are discussed.

The yield of γ-rays emitted in the dissipative reaction 19F + 12C, at Elab = 121.7 MeV has been measured in coincidence with α-particles emitted at θlab = 10°. Comparison with preliminary statistical model calculations shows that assuming only compound nucleaus formation is not sufficient to reproduce the data. Other mechanisms have to be included before information on reaction dynamics can be extracted and definitive conclusions can be drawn.