2,666 research outputs found
The Quadratic Coefficient of the Electron Cloud Mapping
The Electron Cloud is an undesirable physical phenomenon which might produce
single and multi-bunch instability, tune shift, increase of pressure ultimately
limiting the performance of particle accelerators. We report our results on the
analytical study of the electron dynamics.Comment: 5 pages, 7 figures, presented at ECLOUD12: Joint
INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects, La Biodola, Isola
d Elba, Italy, 5-9 June 201
Maps for Electron Clouds: Application to LHC Conditioning
In this communication we present a generalization of the map formalism,
introduced in [1] and [2], to the analysis of electron flux at the chamber wall
with particular reference to the exploration of LHC conditioning scenarios.Comment: 3 pages, 4 figure
Scanning and data extraction from crop collecting mission documents
Poster presented at TDWG 2009, Montpellier (France). 9 - 13 Nov 2009
Underwater acoustic channel properties in the Gulf of Naples and their effects on digital data transmission
In this paper we studied the physical properties of the Gulf of Naples (Southern Italy) for its use as a commu-
nication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to
a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central
frequency of 100 kHz and a band pass of 10 kHz. The main operational requirements of data transmission con-
cern the near horizontal acoustic link, the maximum depth of the sea being about 300 m and the planned hori-
zontal distance between seismic instruments and buoy 2 km. This study constructs the signal-to-noise ratio maps
to understand the limits beyond which the clarity of the transmission is no longer considered reliable. Using ray-
theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmis-
sion loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the trans-
mitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects
predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case
of omnidirectional transmitters with a Source Level (SL) of 165 dB and a baud rate of 2.4 kbit/s, the results al-
so show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections
below 50 m depth in the underwater acoustic channel
A Formula of the Electron Cloud Linear Map Coefficient in a Strong Dipole
Electron cloud effects have recognized as as one of the most serious
bottleneck for reaching design performances in presently running and proposed
future storage rings. The analysis of these effects is usually performed with
very time consuming simulation codes. An alternative analytic approach, based
on a cubic map model for the bunch-to-bunch evolution of the electron cloud
density, could be useful to determine regions in parameters space compatible
with safe machine operations. In this communication we derive a simple
approximate formula relating the linear coefficient in the electron cloud
density map to the parameters relevant for the electron cloud evolution with
particular reference to the LHC dipoles.Comment: 3 pages, 5 figures. Proceeding of IPAC 201
Development of a multi-phase dynamic ray-tracing code
We here propose a method for rapid, high-frequency seismogram
generation that makes use of an algorithm to automatically generate an exhau-
stive set of seismic phases that produce an appreciable amplitude on the sei-
smogram. The method uses a hierarchical order of rays and seismic phases
generation, taking into account some existence constraints for a ray-path and
some physical constraints. To compute synthetic seismograms, the COMRAD
code (from the Italian: “COdice Multifase per il RAy-tracing Dinamico”) uses
as its core a dynamic ray-tracing code. To validate the code, we have computed
in a layered medium synthetic seismograms using both COMRAD and a code
which computes the complete wavefield by the discrete wavenumber method.
The seismograms are compared according to a time-frequency misfit criteria
based on the continuous wavelet transform of the signals. The comparison
shows that the ray-theory seismogram is enough complete and moreover, the
time for the computing of the synthetics using the COMRAD code (truncating the ray series at the 10th generation) is 3-4-fold less than that needed for the
Axitra code (to a frequency of 25 Hz)
Underwater acoustic channel properties in the Gulf of Naples and their effects on digital data transmission
In this paper we studied the physical properties of the Gulf of Naples (Southern Italy) for its use as a commu-
nication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to
a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central
frequency of 100 kHz and a band pass of 10 kHz. The main operational requirements of data transmission con-
cern the near horizontal acoustic link, the maximum depth of the sea being about 300 m and the planned hori-
zontal distance between seismic instruments and buoy 2 km. This study constructs the signal-to-noise ratio maps
to understand the limits beyond which the clarity of the transmission is no longer considered reliable. Using ray-
theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmis-
sion loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the trans-
mitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects
predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case
of omnidirectional transmitters with a Source Level (SL) of 165 dB and a baud rate of 2.4 kbit/s, the results al-
so show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections
below 50 m depth in the underwater acoustic channel
Magnetotelluric investigation in the High Agri Valley (southern Apennine, Italy)
Abstract. In this paper we present the result of a magnetotelluric (MT) investigation carried out across the High Agri Valley (HAV), southern Italy. Several MT soundings were carried out in order to obtain a ~15 km long 2-D resistivity model with an investigation depth of ~10 km. The main aim was to provide valuable data on the geological and structural setting of the HAV. The MT model was compared with pre-existing geological, geophysical and seismic data. The MT model can be schematized as a superposition of three stack lateral varying layers with different thickness and resistivity values: a surficial low–medium resistivity layer associated with the Quaternary deposits and to the allochthonous units; and a deeper high resistivity layer related to the Apulia Platform, separated by a thin layer connected to the mélange zone and to the Pliocene terrigenous marine deposits. Sharp lateral resistivity variations are interpreted as faults that, on the basis of accurate focal mechanism computations, display normal-faulting kinematics
- …