816 research outputs found
Absolute determination of D_s branching ratios and f_{D_s} extraction at a neutrino factory
A method for a direct measurement of the exclusive D_s branching ratios and
of the decay constant f_{D_s} with a systematical error better than 5% is
presented. The approach is based on the peculiar vertex topology of the
anti-neutrino induced diffractive charm events. The statistical accuracy
achievable with a neutrino factory is estimated
Heavy quark studies with nuclear emulsions
Emulsions have started particle physics with the discovery of natural
radioactivity by Becquerel in 1896. The development of the ``nuclear
emulsions'' made it possible to detect tracks of single particle and to perform
detailed measurements of their interactions. The discovery of the pion in 1947
was the first, spectacular demonstration of their unique features for the
direct observation of the production and decay of short-lived particles, with
negligible or very low background. In particular, these features are now
exploited for studies of heavy quark physics in experiments where nuclear
emulsions are combined with electronic detectors and profit is taken of the
remarkable technological progress in automated analysis. In these experiments,
neutrinos provide a selective probe for specific quark flavors. Interesting
results on charm production and decay are expected in the very near future.Comment: To be published on the book for the eightieth birthday of Roberto
Salmeron, World Scientifi
Neutrino oscillations: An experimental review
In this paper we summarize the status of neutrino-oscillation searches from an experimentalist point of view emphasizing the latest results. In particular we report about the Borexino, MINOS, OPERA and MiniBoone results. A brief outlook on the perspectives of this field of research is also given
Accelerator studies of neutrino oscillations
The question of whether the neutrino has a non-vanishing mass plays acrucial role in particle physics. A massive neutrino would unambiguously reveal the existence of new physics beyond the Standard Model. In addition, it could have profound implications on astrophysics and cosmology, with effects on the evolution of the Universe. Experiments aiming at direct neutrino-mass measurements based on kinematics have not been able, so far, to measure the very small neutrino mass. Indirect measurements can be performed by exploiting reactions which may only occur for massive neutrinos. Neutrino oscillation is one of those processes. The mass difference between neutrino mass-eigenstates can be inferred from a phase measurement. This feature allows for high sensitivity experiments. Neutrinos from different sources can be used to search for oscillations: solar neutrinos, neutrinos produced in the interaction of cosmic rays with the atmosphere and artificially produced neutrinos from nuclear reactors and particle accelerators. The latter offer the possibility of choosing the relevant experimental features such as the flux flavour composition, the energy and the baseline distance from the source to the detector.This paper attempts to review the main accelerator experiments whichhave been performed and to outline the future projects. A brief introduction to the theory and phenomenology of neutrino oscillationsis given to help in understanding the scope, the design and the performance of the different experiments
A search for Z' in muon neutrino associated charm production
In many extensions of the Standard Model the presence of an extra neutral
boson, Z', is invoked. A precision study of weak neutral-current exchange
processes involving only second generation fermions is still missing. We
propose a search for Z' in muon neutrino associated charm production. This
process only involves Z' couplings with fermions from the second generation. An
experimental method is thoroughly described using an ideal detector. As an
application, the accuracy reachable with present and future experiments has
been estimated.Comment: 13 pages, 3 figures, late
Acoustic neutrino detection in a Adriatic multidisciplinary observatory (ANDIAMO)
The existence of cosmic accelerators able to emit charged particles up to ZeV energies has been confirmed by the observations made in the last years by experiments such as Auger and Telescope Array. The interaction of such energetic cosmic-rays with gas or low energy photons, surrounding the astrophysical sources or present in the intergalactic medium, guarantee an ultra-high-energy neutrino related emission. When these energetic neutrinos interact in a medium produce a thermo-acoustic process where the energy of generated particle cascades can be conveyed in a pressure pulse propagating into the same medium. The kilometric attenuation length as well as the well-defined shape of the expected pulse suggest a large-area-undersea-array of acoustic sensors as an ideal observatory. For this scope, we propose to exploit the existing and no more operative offshore (oil rigs) powered platforms in the Adriatic sea as the main infrastructure to build an acoustic submarine array of dedicated hydrophones covering a surface area up to 10000 km2 and a volume up to 500 km3. In this work we describe the advantages of this detector concept using a ray tracing technique as well as the scientific goals linked to the challenging purpose of observing for the first time ultra-high-energy cosmic neutrinos. This observatory will be complementary to the dedicated radio array detectors with the advantages of avoiding any possible thermo-acoustic noise from the atmospheric muons
Effect of D-Mannitol on the Microstructure and Rheology of Non-Aqueous Carbopol Microgels
D-mannitol is a common polyol that is used as additive in pharmaceutical and personal care product formulations. We investigated its effect on the microstructure and rheology of novel non-aqueous Carbopol dispersions employing traditional and time-resolved rheological analysis. We considered two types of sample, (i) fresh (i.e., mannitol completely dissolved in solution) and aged (i.e., visible in crystalline form). The analysis of the intracycle rheological transitions that were observed for different samples revealed that, when completely dissolved in solution, mannitol does not alter the rheological behaviour of the Carbopol dispersions. This highlights that the chemical similarity of the additive with the molecules of the surrounding solvent allows preserving the swollen dimension and interparticle interactions of the Carbopol molecules. Conversely, when crystals are present, a hierarchical structure forms, consisting of a small dispersed phase (Carbopol) agglomerated around a big dispersed phase (crystals). In keeping with this microstructural picture, as the concentration of Carbopol reduces, the local dynamics of the crystals gradually start to control the integrity of the microstructure. Rheologically, this results in a higher elasticity of the suspensions at infinitesimal deformations, but a fragile yielding process at intermediate strains
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