1,633 research outputs found
Parametrizations of Inclusive Cross Sections for Pion Production in Proton-Proton Collisions
Accurate knowledge of cross sections for pion production in proton-proton
collisions finds wide application in particle physics, astrophysics, cosmic ray
physics and space radiation problems, especially in situations where an
incident proton is transported through some medium, and one requires knowledge
of the output particle spectrum given the input spectrum. In such cases
accurate parametrizations of the cross sections are desired. In this paper we
review much of the experimental data and compare to a wide variety of different
cross section parametrizations. In so doing, we provide parametrizations of
neutral and charged pion cross sections which provide a very accurate
description of the experimental data. Lorentz invariant differential cross
sections, spectral distributions and total cross section parametrizations are
presented.Comment: 32 pages with 15 figures. Published in Physical Review D62, 094030.
File includes 6 tex files. The main file is paper.tex which has include
statements refering to the rest. figures are in graphs.di
The variable finesse locking technique
Virgo is a power recycled Michelson interferometer, with 3 km long Fabry-Perot cavities in the arms. The locking of the interferometer has been obtained with an original lock acquisition technique. The main idea is to lock the instrument away from its working point. Lock is obtained by misaligning the power recycling mirror and detuning the Michelson from the dark fringe. In this way, a good fraction of light escapes through the antisymmetric port and the power build-up inside the recycling cavity is extremely low. The benefit is that all the degrees of freedom are controlled when they are almost decoupled, and the linewidth of the recycling cavity is large. The interferometer is then adiabatically brought on to the dark fringe. This technique is referred to as variable finesse, since the recycling cavity is considered as a variable finesse Fabry-Perot. This technique has been widely tested and allows us to reach the dark fringe in few minutes, in an essentially deterministic way
Calibration and sensitivity of the Virgo detector during its second science run
The Virgo detector is a kilometer-length interferometer for gravitational
wave detection located near Pisa (Italy). During its second science run (VSR2)
in 2009, six months of data were accumulated with a sensitivity close to its
design. In this paper, the methods used to determine the parameters for
sensitivity estimation and gravitational wave reconstruction are described. The
main quantities to be calibrated are the frequency response of the mirror
actuation and the sensing of the output power. Focus is also put on their
absolute timing. The monitoring of the calibration data as well as the
parameter estimation with independent techniques are discussed to provide an
estimation of the calibration uncertainties. Finally, the estimation of the
Virgo sensitivity in the frequency-domain is described and typical
sensitivities measured during VSR2 are shown.Comment: 30 pages, 23 figures, 1 table. Published in Classical and Quantum
Gravity (CQG), Corrigendum include
Virgo calibration and reconstruction of the gravitational wave strain during VSR1
Virgo is a kilometer-length interferometer for gravitational waves detection
located near Pisa. Its first science run, VSR1, occured from May to October
2007. The aims of the calibration are to measure the detector sensitivity and
to reconstruct the time series of the gravitational wave strain h(t). The
absolute length calibration is based on an original non-linear reconstruction
of the differential arm length variations in free swinging Michelson
configurations. It uses the laser wavelength as length standard. This method is
used to calibrate the frequency dependent response of the Virgo mirror
actuators and derive the detector in-loop response and sensitivity within ~5%.
The principle of the strain reconstruction is highlighted and the h(t)
systematic errors are estimated. A photon calibrator is used to check the sign
of h(t). The reconstructed h(t) during VSR1 is valid from 10 Hz up to 10 kHz
with systematic errors estimated to 6% in amplitude. The phase error is
estimated to be 70 mrad below 1.9 kHz and 6 micro-seconds above.Comment: 8 pages, 8 figures, proceedings of Amaldi 8 conference, to be
published in Journal of Physics Conference Series (JPCS). Second release:
correct typo
Reconstruction of the gravitational wave signal during the Virgo science runs and independent validation with a photon calibrator
The Virgo detector is a kilometer-scale interferometer for gravitational wave
detection located near Pisa (Italy). About 13 months of data were accumulated
during four science runs (VSR1, VSR2, VSR3 and VSR4) between May 2007 and
September 2011, with increasing sensitivity.
In this paper, the method used to reconstruct, in the range 10 Hz-10 kHz, the
gravitational wave strain time series from the detector signals is
described. The standard consistency checks of the reconstruction are discussed
and used to estimate the systematic uncertainties of the signal as a
function of frequency. Finally, an independent setup, the photon calibrator, is
described and used to validate the reconstructed signal and the
associated uncertainties.
The uncertainties of the time series are estimated to be 8% in
amplitude. The uncertainty of the phase of is 50 mrad at 10 Hz with a
frequency dependence following a delay of 8 s at high frequency. A bias
lower than and depending on the sky direction of the GW is
also present.Comment: 35 pages, 16 figures. Accepted by CQ
Scientific Objectives of Einstein Telescope
The advanced interferometer network will herald a new era in observational
astronomy. There is a very strong science case to go beyond the advanced
detector network and build detectors that operate in a frequency range from 1
Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors
will be able to probe a range of topics in nuclear physics, astronomy,
cosmology and fundamental physics, providing insights into many unsolved
problems in these areas.Comment: 18 pages, 4 figures, Plenary talk given at Amaldi Meeting, July 201
A Cross-correlation method to search for gravitational wave bursts with AURIGA and Virgo
We present a method to search for transient GWs using a network of detectors
with different spectral and directional sensitivities: the interferometer Virgo
and the bar detector AURIGA. The data analysis method is based on the
measurements of the correlated energy in the network by means of a weighted
cross-correlation. To limit the computational load, this coherent analysis step
is performed around time-frequency coincident triggers selected by an excess
power event trigger generator tuned at low thresholds. The final selection of
GW candidates is performed by a combined cut on the correlated energy and on
the significance as measured by the event trigger generator. The method has
been tested on one day of data of AURIGA and Virgo during September 2005. The
outcomes are compared to the results of a stand-alone time-frequency
coincidence search. We discuss the advantages and the limits of this approach,
in view of a possible future joint search between AURIGA and one
interferometric detector.Comment: 11 pages, 6 figures, submitted to CQG special issue for Amaldi 7
Proceeding
Tests of the Equivalence Principle with Neutral Kaons
We test the Principle of Equivalence for particles and antiparticles, using
CPLEAR data on tagged K0 and K0bar decays into pi^+ pi^-. For the first time,
we search for possible annual, monthly and diurnal modulations of the
observables |eta_{+-}| and phi_{+-}, that could be correlated with variations
in astrophysical potentials. Within the accuracy of CPLEAR, the measured values
of |eta_{+-}| and phi_{+-} are found not to be correlated with changes of the
gravitational potential. We analyze data assuming effective scalar, vector and
tensor interactions, and we conclude that the Principle of Equivalence between
particles and antiparticles holds to a level of 6.5, 4.3 and 1.8 x 10^{-9},
respectively, for scalar, vector and tensor potentials originating from the Sun
with a range much greater than the distance Earth-Sun. We also study
energy-dependent effects that might arise from vector or tensor interactions.
Finally, we compile upper limits on the gravitational coupling difference
between K0 and K0bar as a function of the scalar, vector and tensor interaction
range.Comment: 15 pages latex 2e, five figures, one style file (cernart.csl)
incorporate
Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR
We use fits to recent published CPLEAR data on neutral kaon decays to
and to constrain the CPT--violation parameters
appearing in a formulation of the neutral kaon system as an open
quantum-mechanical system. The obtained upper limits of the CPT--violation
parameters are approaching the range suggested by certain ideas concerning
quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures
ChPT tests at the NA48 and NA62 experiments at CERN
The NA48/2 Collaboration at CERN has accumulated unprecedented statistics of
rare kaon decays in the Ke4 modes: Ke4(+-) ()
and Ke4(00) () with nearly one percent
background contamination. The detailed study of form factors and branching
rates, based on these data, has been completed recently. The results brings new
inputs to low energy strong interactions description and tests of Chiral
Perturbation Theory (ChPT) and lattice QCD calculations. In particular, new
data support the ChPT prediction for a cusp in the invariant mass
spectrum at the two charged pions threshold for Ke4(00) decay. New final
results from an analysis of about 400 rare
decay candidates collected by the NA48/2 and NA62 experiments at CERN during
low intensity runs with minimum bias trigger configurations are presented. The
results include a model-independent decay rate measurement and fits to ChPT
description.Comment: XIIth International Conference on Heavy Quarks and Leptons 2014,
Mainz, German
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