A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10{sup 18} eV at the Pierre Auger Observatory is presented. This search is ...performed as a function of both declination and right ascension in several energy ranges above 10{sup 18} eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 10{sup 18} eV from stationary Galactic sources densely distributed in the Galactic disk and predominantly emitting light particles in all directions.
The surface detector array of the Pierre Auger Observatory can detect neutrinos with energy E{sub {nu}} between 10{sup 17} eV and 10{sup 20} eV from point-like sources across the sky south of +55 ...Degree-Sign and north of -65 Degree-Sign declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavors in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrino interactions in Earth's crust (Earth-skimming neutrinos). No candidate neutrinos have been found in data up to 2010 May 31. This corresponds to an equivalent exposure of {approx}3.5 years of a full surface detector array for the Earth-skimming channel and {approx}2 years for the downward-going channel. An improved upper limit on the diffuse flux of tau neutrinos has been derived. Upper limits on the neutrino flux from point-like sources have been derived as a function of the source declination. Assuming a differential neutrino flux k{sub PS} {center_dot} E {sup -2}{sub {nu}} from a point-like source, 90% confidence level upper limits for k{sub PS} at the level of Almost-Equal-To 5 Multiplication-Sign 10{sup -7} and 2.5 Multiplication-Sign 10{sup -6} GeV cm{sup -2} s{sup -1} have been obtained over a broad range of declinations from the searches for Earth-skimming and downward-going neutrinos, respectively.
The K2K SciBar detector Nitta, K.; Aliu, E.; Andringa, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2004, Letnik:
535, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A new near detector, Scintillator Bar (SciBar), for the K2K long-baseline neutrino oscillation experiment was installed to improve the measurement of the neutrino energy spectrum and to study ...neutrino interactions in the energy region around 1
GeV. SciBar is a `fully active' tracking detector with fine segmentation consisting of plastic scintillator bars. The detector was constructed in the summer of 2003 and is taking data since October 2003. The basic design and initial performance are presented.
Vector boson decays of the Higgs boson Romão, J.C.; Andringa, S.
The European physical journal. C, Particles and fields,
1999, Letnik:
7, Številka:
4
Journal Article
The cross section for neutron interactions on argon is an important design and operational parameter for a number of neutrino, dark matter, and neutrinoless double beta decay experiments which use ...liquid argon as a detection or shielding medium. There is a discrepancy between the evaluated total cross section in the \(20\) to \(70~\rm\)\,keV neutron kinetic energy region given in the ENDF database and a single measurement conducted by an experiment with a thin target (0.2 atoms/barn) optimized for higher cross sections. This gives rise to significant uncertainty in the interaction length of neutrons in liquid argon. This discrepancy is now resolved by new results presented here from the Argon Resonance Transport Interaction Experiment (ARTIE), a thick target experiment (3.3 atoms/barn) optimized for the small cross sections in this energy region.
We report a measurement of the flux of cosmic rays with unprecedented precision and statistics using the Pierre Auger Observatory. Based on fluorescence observations in coincidence with at least one ...surface detector we derive a spectrum for energies above 10^18 eV. We also update the previously published energy spectrum obtained with the surface detector array. The two spectra are combined addressing the systematic uncertainties and, in particular, the influence of the energy resolution on the spectral shape. The spectrum can be described by a broken power law E^-gamma with index gamma=3.3 below the ankle which is measured at log10(E/eV) = 18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log10(E/eV) = 19.5, detected with high statistical significance.
We calculate the two-loop contributions to the electric dipole moments of the electron and the neutron mediated by charged Higgs in a generic supersymmetric theories. The new contributions are ...originated from the potential CP violation in the trilinear couplings of the charged Higgs bosons to the scalar-top or the scalar-bottom quarks. These couplings did not receive stringent constraints directly. We find observable effects for a sizable portion of the parameter space related to the third generation scalar-quarks in the minimal supersymmetric standard model.
Over the last two decades, the possibility of using RPCs in outdoors systems has increased considerably. Our group has participated in this effort having installed several systems and continues to ...work on their optimization, while simultaneously studying and developing new approaches that can to use of RPCs in outdoor applications. In particular, some detectors were deployed in the field at the Pierre Auger Observatory in 2019 remained inactive, awaiting the commissioning of support systems. During the pandemic the detectors were left without gas flow for more than two years, but were recently reactivated with no major problems. The LouMu project combines particle physics and geophysics in order to map large geologic structures, using Muon Tomography. The development of the RPC system used and the data from the last two years will be presented. Finally, recent advances in a large area (1 m2) double gap-sealed RPC will be presented.
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