62 research outputs found
Measuring general relativity effects in a terrestrial lab by means of laser gyroscopes
GINGER is a proposed tridimensional array of laser gyroscopes with the aim of measuring the Lense-Thirring effect, predicted by the General Relativity theory, in a terrestrial laboratory environment. We discuss the required accuracy, the methods to achieve it, and the preliminary experimental work in this directio
Measuring Gravito-magnetic Effects by Multi Ring-Laser Gyroscope
We propose an under-ground experiment to detect the general relativistic
effects due to the curvature of space-time around the Earth (de Sitter effect)
and to rotation of the planet (dragging of the inertial frames or
Lense-Thirring effect). It is based on the comparison between the IERS value of
the Earth rotation vector and corresponding measurements obtained by a
tri-axial laser detector of rotation. The proposed detector consists of six
large ring-lasers arranged along three orthogonal axes.
In about two years of data taking, the 1% sensitivity required for the
measurement of the Lense-Thirring drag can be reached with square rings of 6
side, assuming a shot noise limited sensitivity ().
The multi-gyros system, composed of rings whose planes are perpendicular to one
or the other of three orthogonal axes, can be built in several ways. Here, we
consider cubic and octahedron structures. The symmetries of the proposed
configurations provide mathematical relations that can be used to study the
stability of the scale factors, the relative orientations or the ring-laser
planes, very important to get rid of systematics in long-term measurements,
which are required in order to determine the relativistic effects.Comment: 24 pages, 26 Postscript figure
Measuring gravito-magnetic effects by multi ring-laser gyroscope
We propose an under-ground experiment to detect the general relativistic effects due to the curvature of space-time around the Earth (de Sitter effect) and to the rotation of the planet (dragging
of the inertial frames or Lense-Thirring effect). It is based on the comparison between the IERS value of the Earth rotation vector and corresponding measurements obtained by a tri-axial laser
detector of rotation. The proposed detector consists of six large ring-lasers arranged along three orthogonal axes. In about two years of data taking, the 1% sensitivity required for the measurement of the Lense-Thirring drag can be reached with square rings of 6 m side, assuming a shot noise limited sensitivity (20prad/s/sqrt(Hz). The multi-gyros system, composed of rings whose planes are perpendicular to one or the other of three orthogonal axes, can be built in several ways. Here, we consider cubic and octahedral structures. It is shown that the symmetries of the proposed configurations provide mathematical relations that can be used to ensure the long term stability of the apparatus
Measurement of the atmospheric muon flux with the NEMO Phase-1 detector
The NEMO Collaboration installed and operated an underwater detector
including prototypes of the critical elements of a possible underwater km3
neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box.
The detector was developed to test some of the main systems of the km3
detector, including the data transmission, the power distribution, the timing
calibration and the acoustic positioning systems as well as to verify the
capabilities of a single tridimensional detection structure to reconstruct muon
tracks. We present results of the analysis of the data collected with the NEMO
Mini-Tower. The position of photomultiplier tubes (PMTs) is determined through
the acoustic position system. Signals detected with PMTs are used to
reconstruct the tracks of atmospheric muons. The angular distribution of
atmospheric muons was measured and results compared with Monte Carlo
simulations.Comment: Astrop. Phys., accepte
Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower
The results of the analysis of the data collected with the NEMO Phase-2
tower, deployed at 3500 m depth about 80 km off-shore Capo Passero (Italy), are
presented. Cherenkov photons detected with the photomultipliers tubes were used
to reconstruct the tracks of atmospheric muons. Their zenith-angle distribution
was measured and the results compared with Monte Carlo simulations. An
evaluation of the systematic effects due to uncertainties on environmental and
detector parameters is also included. The associated depth intensity relation
was evaluated and compared with previous measurements and theoretical
predictions. With the present analysis, the muon depth intensity relation has
been measured up to 13 km of water equivalent.Comment: submitted to Astroparticle Physic
Sensitivity of an underwater Cerenkov km3 telescope to TeV neutrinos from Galactic Microquasars
In this paper are presented the results of Monte Carlo simulations on the
capability of the proposed NEMO-km telescope to detect TeV muon neutrinos
from Galactic microquasars. For each known microquasar we compute the number of
detectable events, together with the atmospheric neutrino and muon background
events. We also discuss the detector sensitivity to neutrino fluxes expected
from known microquasars, optimizing the event selection also to reject the
background; the number of events surviving the event selection are given. The
best candidates are the steady microquasars SS433 and GX339-4 for which we
estimate a sensitivity of about erg/cm s; the predicted
fluxes are expected to be well above this sensitivity. For bursting
microquasars the most interesting candidates are Cygnus X-3, GRO J1655-40 and
XTE J1118+480: their analyses are more complicated because of the stochastic
nature of the bursts.Comment: 20 pages, 3 figures, accepted by Astroparticle Physic
Deep sea tests of a prototype of the KM3NeT digital optical module
The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deepwaters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same (40)Kdecay and the localisation of bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions
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