2,490 research outputs found
The BepiColombo MORE gravimetry and rotation experiments with the ORBIT14 software
The BepiColombomission to Mercury is an ESA/JAXAcornerstone mission, consisting of two spacecraft in orbit around Mercury addressing several scientific issues. One spacecraft is the Mercury Planetary Orbiter, with full instrumentation to perform radio science experiments. Very precise radio tracking from Earth, on-board accelerometer and optical measurements will provide large data sets. From these it will be possible to study the global gravity field of Mercury and its tidal variations, its rotation state and the orbit of its centre of mass. With the gravity field and rotation state, it is possible to constrain the internal structure of the planet. With the orbit of Mercury, it is possible to constrain relativistic theories of gravitation. In order to assess that all the scientific goals are achievable with the required level of accuracy, full cycle numerical simulations of the radio science experiment have been performed. Simulated tracking, accelerometer and optical camera data have been generated, and a long list of variables including the spacecraft initial conditions, the accelerometer calibrations and the gravity field coefficients have been determined by a least-squares fit. The simulation results are encouraging: The experiments are feasible at the required level of accuracy provided that some critical terms in the accelerometer error are moderated. We will show that BepiColombo will be able to provide at least an order of magnitude improvement in the knowledge of Love number k2, libration amplitudes and obliquity, along with a gravity field determination up to degree 25 with a signal-to-noise ratio of 10
Study of W± boson in the ALICE muon spectrometer: considerations and analysis using the HLT tool
W± bosons produced in proton-proton collisions can be observed in the ALICE muon spectrometer via their decay into single muons at a transverse momentum, pt ~ Mw/2 40 GeV/c. However the identification of these single muons is complicated by a large amount of muonic background, especially in the low pt region. Therefore, it is necessary to apply precise pt cuts below the region of interest. This can be done by means of the High Level Trigger (HLT). In this paper we present the performance of detecting high pt muons at the HLT level. In order to improve the momentum resolution of the L0 trigger, fast clusterization of the tracking chambers together with L0 trigger matching and fast tracking reconstruction is applied. This will reduce the background in the high pt muon analysis
The BepiColombo MORE gravimetry and rotation experiments with the ORBIT14 software
open6noopenG. Schettino, S. Di Ruzza, S. Cicalò, G. Tommei;
A. Milani Comparetti; E.M. AlessiSchettino, G.; DI RUZZA, Sara; Cicalò, S.; Tommei, G.; Milani Comparetti, A.; Alessi, E. M
Simple predictions from ALCOR_c for rehadronisation of charmed quark matter
We study the production of charmed hadrons with the help of ALCOR_c, the
algebraic coalescence model for rehadronisation of charmed quark matter.
Mesonic ratios are introduced as factors connecting various antibaryon to
baryon ratios. The resulting simple relations could serve as tests of quark
matter formation and coalescence type rehadronization in heavy ion collisions.Comment: 7 pages in Latex, 1 PS figur
Study of dimuon production in Indium-Indium collisions with the NA60 experiment
The NA60 experiment at the CERN-SPS is devoted to the study of dimuon
production in heavy-ion and proton-nucleus collisions. We present preliminary
results from the analysis of Indium-Indium collisions at 158 GeV per nucleon.
The topics covered are low mass vector meson production, J/psi production and
suppression, and the feasibility of the open charm measurement from the dimuon
continuum in the mass range below the J/psi peak.Comment: Contribution at XXXXth Rencontres de Moriond, "QCD and High Energy
Hadronic Interactions
First results from the NA60 experiment at CERN
Since 1986, several heavy ion experiments have studied some signatures of the
formation of the quark-gluon plasma and a few exciting results have been found.
However, some important questions are still unanswered and require new
measurements. The NA60 experiment, with a new detector concept that vastly
improves dimuon detection in proton-nucleus and heavy-ion collisions, studies
several of those open questions, including the production of open charm. This
paper presents the experiment and some first results from data collected in
2002.Comment: Paper presented at the XXXVIII Rencontres de Moriond, QCD and High
Energy Hadronic Interactions, Les Arcs, March 22-29, 2003. 4 pages, 6 figure
Meson Production in In-In Collisions and the Puzzle
The NA60 experiment measured dimuon production in In-In collisions at 158
AGeV. This paper presents a high statistics measurement of with
the specific objective to provide insight on the puzzle, i.e. the
difference in the inverse slopes and absolute yields measured by NA49 and
NA50 in the kaon and lepton channel, respectively. Transverse momentum
distributions were studied as a function of centrality. The slope parameter
shows a rapid increase with centrality, followed by a saturation. Variations of
with the fit range of the order of 15 MeV were observed, possibly as a
consequence of radial flow. The meson yield normalized to the number of
participants increases with centrality and is consistently higher than the
yield measured by the NA49 experiment at any centrality.Comment: 4 Pages, 2 Figures. Proceedings of the 20 International
Conference on Ultra-Relativistic Nucleus Nucleus Collision
The Extreme Energy Events HECR array: status and perspectives
The Extreme Energy Events Project is a synchronous sparse array of 52
tracking detectors for studying High Energy Cosmic Rays (HECR) and Cosmic
Rays-related phenomena. The observatory is also meant to address Long Distance
Correlation (LDC) phenomena: the network is deployed over a broad area covering
10 degrees in latitude and 11 in longitude. An overview of a set of preliminary
results is given, extending from the study of local muon flux dependance on
solar activity to the investigation of the upward-going component of muon flux
traversing the EEE stations; from the search for anisotropies at the sub-TeV
scale to the hints for observations of km-scale Extensive Air Shower (EAS).Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.
Low Mass Dimuon Production in Indium-Indium Collisions at the CERN SPS
NA60 is a fixed-target experiment at the CERN SPS which measured dimuon
production in nucleus-nucleus and proton-nucleus collisions. In this paper we
report on a precision measurement of low-mass muon pairs in 158 AGeV
indium-indium collisions. A significant excess of pairs is observed above the
yield expected from neutral meson decays. The excess can be isolated by
subtraction of expected sources, thanks to the excellent mass resolution and
large sample size.Comment: 4 pages, 3 figures, Contribution at XLIst Rencontres de Moriond, "QCD
and High Energy Hadronic Interactions
Thermal dileptons at SPS energies
Clear signs of excess dileptons above the known sources were found at the SPS
since long. However, a real clarification of these observations was only
recently achieved by NA60, measuring dimuons with unprecedented precision in
158A GeV, In-In collisions. The excess mass spectrum in the region M<1 GeV is
consistent with a dominant contribution from pi+pi- -> rho -> mu+mu-
annihilation. The associated rho spectral function shows a strong broadening,
but essentially no shift in mass. In the region M>1 GeV, the excess is found to
be prompt, not due to enhanced charm production. The inverse slope parameter
Teff associated with the transverse momentum spectra rises with mass up to the
rho, followed by a sudden decline above. While the initial rise, coupled to a
hierarchy in hadron freeze-out, points to radial flow of a hadronic decay
source, the decline above signals a transition to a low-flow source, presumably
of partonic origin. The mass spectra show at low transverse momenta the steep
rise towards low masses characteristic for Planck-like radiation. The
polarization of the excess referred to the Collins Soper frame is found to be
isotropic. All observations are consistent with the interpretation of the
excess as thermal radiation.Comment: Prepared for 20th International Conference on Ultra-Relativistic
Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008), Jaipur, India, 4-10
Feb. 200
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