271 research outputs found
Large-angle scattering of multi-GeV muons on thin Lead targets
The probability of large-angle scattering for multi-GeV muons in thin () lead targets is studied. The new estimates presented here are
based both on simulation programs (GEANT4 libraries) and theoretical
calculations. In order to validate the results provided by simulation, a
comparison is drawn with experimental data from the literature. This study is
particularly relevant when applied to muons originating from
interactions of CNGS beam neutrinos. In that circumstance the process under
study represents the main background for the search in
the channel for the OPERA experiment at LNGS. Finally, we also
investigate, in the CNGS context, possible contributions from the muon
photo-nuclear process which might in principle also produce a large-angle muon
scattering signature in the detector
A compact light readout system for longitudinally segmented shashlik calorimeters
The longitudinal segmentation of shashlik calorimeters is challenged by dead
zones and non-uniformities introduced by the light collection and readout
system. This limitation can be overcome by direct fiber-photosensor coupling,
avoiding routing and bundling of the wavelength shifter fibers and embedding
ultra-compact photosensors (SiPMs) in the bulk of the calorimeter. We present
the first experimental test of this readout scheme performed at the CERN PS-T9
beamline in 2015 with negative particles in the 1-5~GeV energy range. In this
paper, we demonstrate that the scheme does not compromise the energy resolution
and linearity compared with standard light collection and readout systems. In
addition, we study the performance of the calorimeter for partially contained
charged hadrons to assess the separation capability and the response of
the photosensors to direct ionization.Comment: To appear in Nuclear Instruments and Methods in Physics Research,
A narrow band neutrino beam with high precision flux measurements
The ENUBET facility is a proposed narrow band neutrino beam where lepton
production is monitored at single particle level in the instrumented decay
tunnel. This facility addresses simultaneously the two most important
challenges for the next generation of cross section experiments: a superior
control of the flux and flavor composition at source and a high level of
tunability and precision in the selection of the energy of the outcoming
neutrinos. We report here the latest results in the development and test of the
instrumentation for the decay tunnel. Special emphasis is given to irradiation
tests of the photo-sensors performed at INFN-LNL and CERN in 2017 and to the
first application of polysiloxane-based scintillators in high energy physics.Comment: Poster presented at NuPhys2017 (London, 20-22 December 2017). 5
pages, 2 figure
Limited impacts of experimental flow releases on water quality and macroinvertebrate community composition in an upland regulated river
River regulation following the construction of dams has affected the hydrology, water quality, and biology of watercourses across the globe. The term âenvironmental flowsâ has been used to describe measures that can be employed to return some lost elements of the natural flow regime. Their introduction has been suggested as a way to mitigate the impacts of river regulation throughout the world, but understanding of the effects of artificial high flows on water quality and biota is limited for many different river types. We report a field study that manipulated compensation flows from reservoirs in the Pennine uplands of northern England and measured changes in water quality and benthic macroinvertebrates using a beforeâafterâcontrolâimpact approach. These resulted in minor shortâterm changes in water quality, but there was no evidence of immediate (within 48 hr) responses by the macroinvertebrate community to individual flow releases. However, a shift in macroinvertebrate community composition was found after multiple releases, characterized by reductions in Amphinemura sulcicollis (Plecoptera) and Baetis rhodani (Ephemeroptera) and changes in the density of all Diptera. The introduction of shortâterm flow pulses in flashy regulated river systems is unlikely to yield significant changes in water quality and biota. Nevertheless, cumulative rather than single environmental flow events show promise for mitigating some of the impacts of river regulation. More widely, our findings indicate that environmental flow releases from reservoirs may have to go beyond occasional experimental high flow releases if these rivers are to more closely mimic unregulated river systems
Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches
Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the neutron-induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 per year per kilogram, fully compatible with the design of a 10 kg Ă year exposure
Emulsion sheet doublets as interface trackers for the OPERA experiment
New methods for efficient and unambiguous interconnection between electronic
counters and target units based on nuclear photographic emulsion films have
been developed. The application to the OPERA experiment, that aims at detecting
oscillations between mu neutrino and tau neutrino in the CNGS neutrino beam, is
reported in this paper. In order to reduce background due to latent tracks
collected before installation in the detector, on-site large-scale treatments
of the emulsions ("refreshing") have been applied. Changeable Sheet (CSd)
packages, each made of a doublet of emulsion films, have been designed,
assembled and coupled to the OPERA target units ("ECC bricks"). A device has
been built to print X-ray spots for accurate interconnection both within the
CSd and between the CSd and the related ECC brick. Sample emulsion films have
been extensively scanned with state-of-the-art automated optical microscopes.
Efficient track-matching and powerful background rejection have been achieved
in tests with electronically tagged penetrating muons. Further improvement of
in-doublet film alignment was obtained by matching the pattern of low-energy
electron tracks. The commissioning of the overall OPERA alignment procedure is
in progress.Comment: 19 pages, 19 figure
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