0000000000186191
AUTHOR
F. Gramegna
High intensity neutrino oscillation facilities in Europe
The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Frejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of mu(+) and mu(-) beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neu…
Pulse shape analysis of liquid scintillators for neutron studies
The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate ð 1G S=sÞ has been investigated. The possibility to record the signal waveform is of great advantage in studies with g’s and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by g-rays and neutrons have been studied for two different liquid scintillators, NE213 and C6D6: A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n=g discrimination is analyzed, together with the capability to identify a…
Neutron capture cross section measurements for nuclear astrophyisics at CERN n_TOF
A series of neutron capture cross section measurements of interest to nuclear astrophysics have been recently performed at n_TOF, the neutron spallation source operating at CERN. The low repetition frequency of the proton beam driver, the extremely high instantaneous neutron flux, and the low background conditions in the experimental area are optimal for capture cross section measurements on low-mass or radioactive samples. An overview of the measurements performed during the two experimental campaigns in 2002 and 2003 is presented with special emphasis on the measurement of the capture cross sections of the Os isotopes relevant for the cosmochronology based on the Re/Os clock. http://www.s…
Neutron measurements for advanced nuclear systems: The n_TOF project at CERN
A few years ago, the neutron time-of-flight facility n_TOF was built at CERN to address some of the urgent needs of high-accuracy nuclear data for Accelerator Driven Systems and other advanced nuclear energy systems, as well as for nuclear astrophysics and fundamental nuclear physics. Thanks to the characteristics of the neutron beam, and to state-of-the-art detection and acquisition systems, high quality neutron cross-section data have been obtained for a variety of isotopes, many of which radioactive. Following an important upgrade of the spallation target and of the experimental area, a new measurement campaign has started last year. After a brief review of the most important results obt…
Neutron cross section measurements at n_TOF for ADS related estudies
A neutron Time-of-Flight facility (n_TOF) is available at CERN since 2001. The innovative features of the neutron beam, in particular the high instantaneous flux, the wide energy range, the high resolution and the low background, make this facility unique for measurements of neutron induced reactions relevant to the field of Emerging Nuclear Technologies, as well as to Nuclear Astrophysics and Fundamental Nuclear Physics. The scientific motivations that have led to the construction of this new facility are here presented. The main characteristics of the n_TOF neutron beam are described, together with the features of the experimental apparata used for cross-section measurements. The main res…
Evolution of collectivity in the78Ni region: Coulomb excitation of74Ni at intermediate energies.
The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic ob- servables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the ef- fective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope ( 64 Ni) towards the 78 Ni nucleus where the large neu…
Measurement of the n-TOF beam profile with a micromegas detector
A Micromegas detector was used in the neutron Time-Of-Flight (n_TOF) facility at CERN to evaluate the spatial distribution of the neutron beam as a function of its kinetic energy. This was achieved over a large range of neutron energies by using two complementary processes: at low energy by capture of a neutron via the 6Li(n,[alpha])t reaction, and at high energy by elastic scattering of neutrons on gas nuclei (argon+isobutane or helium+isobutane). Data are compared to Monte Carlo simulations and an analytic function fitting the beam profile has been calculated with a sufficient precision to use in neutron capture experiments at the n_TOF facility. http://www.sciencedirect.com/science/artic…
Measurement of the 151Sm n,gamma 152Sm cross section at n_TOF
The 151 Sm(n, γ ) 152 Sm cross section, which is important for the interpretation of the 151 Sm branching as an s -process thermometer, was measured from 1 eV up to 1 MeV at the innovative n_TOF facility at CERN. Based on these data, the Maxwellian-averaged cross section at k T = 30 keV is found to be 3100±160 mb. This value can be used to constrain the thermodynamical conditions in Asymptotic Giant Branch (AGB) stars during He-shell burning.
Measurement of the 241Am neutron capture cross section at the n-TOF facility at CERN
New neutron cross section measurements of minor actinides have been performed recently in order to reduce the uncertainties in the evaluated data, which is important for the design of advanced nuclear reactors and, in particular, for determining their performance in the transmutation of nuclear waste. We have measured the 241 Am(n,γ) cross section at the n TOF facility between 0.2 eV and 10 keV with a BaF2 Total Absorption Calorimeter, and the analysis of the measurement has been recently concluded. Our results are in reasonable agreement below 20 eV with the ones published by C. Lampoudis et al. in 2013, who reported a 22% larger capture cross section up to 110 eV compared to experimental …
Measurements of the 90,91,92,94,96 Zr n, gamma cross-sections at n_TOF
Neutron capture cross sections of the 90,91,92,94,96Zr have been measured over the energy range from 1 eV to 1 MeV at the spallation neutron facility n TOF at CERN in 2003. The innovative features of the neutron beam, in particular the high instantaneous flux, the high energy resolution and low background, together with improvements of the neutron sensitivity of the capture detectors make this facility unique for neutron-induced reaction cross section measurements with much improved accuracy. The preliminary results of the Zr measurements show capture resonance strengths generally smaller than in previous measurements. Peer Reviewed