1,262 research outputs found
U and Th content in the Central Apennines continental crust: a contribution to the determination of the geo-neutrinos flux at LNGS
The regional contribution to the geo-neutrino signal at Gran Sasso National
Laboratory (LNGS) was determined based on a detailed geological, geochemical
and geophysical study of the region. U and Th abundances of more than 50
samples representative of the main lithotypes belonging to the Mesozoic and
Cenozoic sedimentary cover were analyzed. Sedimentary rocks were grouped into
four main "Reservoirs" based on similar paleogeographic conditions and
mineralogy. Basement rocks do not outcrop in the area. Thus U and Th in the
Upper and Lower Crust of Valsugana and Ivrea-Verbano areas were analyzed. Based
on geological and geophysical properties, relative abundances of the various
reservoirs were calculated and used to obtain the weighted U and Th abundances
for each of the three geological layers (Sedimentary Cover, Upper and Lower
Crust). Using the available seismic profile as well as the stratigraphic
records from a number of exploration wells, a 3D modelling was developed over
an area of 2^{\circ}x2^{\circ} down to the Moho depth, for a total volume of
about 1.2x10^6 km^3. This model allowed us to determine the volume of the
various geological layers and eventually integrate the Th and U contents of the
whole crust beneath LNGS. On this base the local contribution to the
geo-neutrino flux (S) was calculated and added to the contribution given by the
rest of the world, yielding a Refined Reference Model prediction for the
geo-neutrino signal in the Borexino detector at LNGS: S(U) = (28.7 \pm 3.9) TNU
and S(Th) = (7.5 \pm 1.0) TNU. An excess over the total flux of about 4 TNU was
previously obtained by Mantovani et al. (2004) who calculated, based on general
worldwide assumptions, a signal of 40.5 TNU. The considerable thickness of the
sedimentary rocks, almost predominantly represented by U- and Th- poor
carbonatic rocks in the area near LNGS, is responsible for this difference.Comment: 45 pages, 5 figures, 12 tables; accepted for publication in GC
ProtoDUNEs
These proceedings review the two DUNE prototype detectors, namely Single- and
Dual-Phase ProtoDUNEs. The detectors, both employing liquid argon Time
Projection Chambers (LAr TPCs), are currently being built at CERN as part of
the ProtoDUNE experimental programme. Such R&D programme aims at validating the
prototypes design and technology, which will eventually be applied to the DUNE
Far Detector at the Sanford Underground Research Facility (SURF).Comment: Talk presented at NuPhys2016 (London, 12-14 December 2016). 8 pages,
LaTeX, 3 figure
WARP: a WIMP double phase Argon detector
The WARP programme for dark matter search with a double phase argon detector
is presented. In such a detector both excitation and ionization produced by an
impinging particle are evaluated by the contemporary measurement of primary
scintillation and secondary (proportional) light signal, this latter being
produced by extracting and accelerating ionization electrons in the gas phase.
The proposed technique, verified on a 2.3 liters prototype, could be used to
efficiently discriminate nuclear recoils, induced by WIMP's interactions, and
measure their energy spectrum. An overview of the 2.3 liters results and of the
proposed 100 liters detector is shown.Comment: Proceeding for IDM200
New results on solar neutrino fluxes from 192 days of Borexino data
We report the direct measurement of the ^7Be solar neutrino signal rate
performed with the Borexino detector at the Laboratori Nazionali del Gran
Sasso. The interaction rate of the 0.862 MeV ^7Be neutrinos is
49+-3(stat)+-4(syst) counts/(day * 100ton). The hypothesis of no oscillation
for ^7Be solar neutrinos is inconsistent with our measurement at the 4sigma
level. Our result is the first direct measurement of the survival probability
for solar nu_e in the transition region between matter-enhanced and
vacuum-driven oscillations. The measurement improves the experimental
determination of the flux of ^7Be, pp, and CNO solar nu_e, and the limit on the
magnetic moment of neutrinos
Measurement of the muon decay spectrum with the ICARUS liquid Argon TPC
Examples are given which prove the ICARUS detector quality through relevant
physics measurements. We study the muon decay energy spectrum from a sample of
stopping muon events acquired during the test run of the ICARUS T600 detector.
This detector allows the spatial reconstruction of the events with fine
granularity, hence, the precise measurement of the range and dE/dx of the muon
with high sampling rate. This information is used to compute the calibration
factors needed for the full calorimetric reconstruction of the events. The
Michel rho parameter is then measured by comparison of the experimental and
Monte Carlo simulated muon decay spectra, obtaining rho = 0.72 +/- 0.06(stat.)
+/- 0.08(syst.). The energy resolution for electrons below ~50 MeV is finally
extracted from the simulated sample, obtaining (Emeas-Emc)/Emc =
11%/sqrt(E[MeV]) + 2%.Comment: 16 pages, 8 figures, LaTex, A4. Some text and 1 figure added. Final
version as accepted for publication in The European Physical Journal
Probing New Physics with Underground Accelerators and Radioactive Sources
New light, weakly coupled particles can be efficiently produced at existing
and future high-intensity accelerators and radioactive sources in deep
underground laboratories. Once produced, these particles can scatter or decay
in large neutrino detectors (e.g Super-K and Borexino) housed in the same
facilities. We discuss the production of weakly coupled scalars via
nuclear de-excitation of an excited element into the ground state in two viable
concrete reactions: the decay of the excited state of O populated
via a reaction on fluorine and from radioactive Ce decay
where the scalar is produced in the de-excitation of Nd, which
occurs along the decay chain. Subsequent scattering on electrons,
, yields a mono-energetic signal that is observable in
neutrino detectors. We show that this proposed experimental set-up can cover
new territory for masses and couplings
to protons and electrons, . This parameter space
is motivated by explanations of the "proton charge radius puzzle", thus this
strategy adds a viable new physics component to the neutrino and nuclear
astrophysics programs at underground facilities.Comment: 5 pages, 2 figure
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