594 research outputs found
The PAMELA Time-of-Flight system: status report
Abstract The PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite-borne experiment, scheduled to be launched in 2003, aboard a Soyuz TM2 rocket, is designed to provide a better understanding of the antimatter component of cosmic rays. In the following we report on the features and performances of its scintillator telescope system which will provide the primary experimental trigger and time-of-flight particle identification
A measurement of cosmic ray deuterium from 0.5â2.9 GeV/nucleon
The rare isotopes ^(2)H and ^(3)He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The unique propagation history of these rare isotopes provides important constraints on galactic cosmic ray source spectra and on models for their propagation within the Galaxy. Hydrogen and helium isotopes were measured with the balloon-borne experiment, IMAX, which flew from Lynn Lake, Manitoba in 1992. The energy spectrum of deuterium between 0.5 and 3.2 GeV/nucleon measured by the IMAX experiment as well as previously published results of ^(3)He from the same instrument will be compared with predictions of cosmic ray galactic propagation models. The observed composition of the light isotopes is found to be generally consistent with the predictions of the standard Leaky Box Model derived to fit observations of heavier nucle
Comparison of 3-Dimensional and 1-Dimensional Schemes in the calculation of Atmospheric Neutrinos
A 3-dimensional calculation of atmospheric neutrinos flux is presented, and
the results are compared with those of a 1-dimensional one. In this study,
interaction and propagation of particles is treated in a 3-dimensional way
including the curvature of charged particles due to the geomagnetic field,
which is assumed to be a dipole field. The purpose of this paper is limited to
the comparison of calculation schemes. The updated flux value with new
interaction model and primary flux model will be reported in a separate paper.
Except for nearly horizontal directions, the flux is very similar to the
result of 1 dimensional calculations. However, for near-horizontal directions
an enhancement of the neutrino flux is seen even at energies as high as 1 GeV.
The production height of neutrinos is lower than the prediction by
1-dimensional calculation for near-horizontal directions, and is a little
higher for near-vertical directions. However, the difference is not evident
except for near-horizontal directions.Comment: 22 pages, 15figure
The ToF and Trigger electronics of the PAMELA experiment
The PAMELA satellite-borne experiment, scheduled to be launched in 2004, is designed to provide a better understanding of the antimatter component of the cosmic rays. Its ToF scintillator system will provide the primary experimental trigger and time-of-flight particle identification. The time resolution requested is Ï, < 120 ps. To fulfill the detector requirements the digitization electronics should have a time resolution †50 ps and provide a wide dynamic range for charge measurements. The peculiarity of the developed electronics arises from the need to obtain such a time resolution operating in a satellite environment, which implies low-power consumption, radiation hardness, redundancy and high reliability
The Time of Flight Detector and Trigger for the Pamela Experiment in Space
The electronics of the Time of Flight telescope and trigger of PAMELA experiment are described. The time resolution requested by the ToF system must be less than 120 ps. The contribution of the digitization electronics is negligible if the TDC resolution is < 50 ps. The peculiarity of the developed electronics arises from the need to obtain such a time resolution associated to a wide dynamic range for charge measurements, operating in satellite environment, which implies low power consumption, radiation hardness, redundancy and high reliabilit
Simulation of Atmospheric Muon and Neutrino Fluxes with CORSIKA
The fluxes of atmospheric muons and neutrinos are calculated by a three
dimensional Monte Carlo simulation with the air shower code CORSIKA using the
hadronic interaction models DPMJET, VENUS, GHEISHA, and UrQMD. For the
simulation of low energy primary particles the original CORSIKA has been
extended by a parametrization of the solar modulation and a microscopic
calculation of the directional dependence of the geomagnetic cut-off functions.
An accurate description for the geography of the Earth has been included by a
digital elevation model, tables for the local magnetic field in the atmosphere,
and various atmospheric models for different geographic latitudes and annual
seasons. CORSIKA is used to calculate atmospheric muon fluxes for different
locations and the neutrino fluxes for Kamioka. The results of CORSIKA for the
muon fluxes are verified by an extensive comparison with recent measurements.
The obtained neutrino fluxes are compared with other calculations and the
influence of the hadronic interaction model, the geomagnetic cut-off and the
local magnetic field on the neutrino fluxes is investigated.Comment: revtex, 19 pages, 19 Postscript figures, submitted to Phys. Rev.
Measurement of the cosmic ray hadron spectrum up to 30 TeV at mountain altitude: the primary proton spectrum
The flux of cosmic ray hadrons at the atmospheric depth of 820 g/cm^2 has
been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore,
National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well
described by a single power law : S(E_h) = (2.25 +- 0.21 +- 0.34(sys))
10^(-7)(E_h/1000)^(-2.79 +- 0.05) m^(-2) s^(-1) sr^(-1) GeV^(-1) over the
energy range 30 GeV-30 TeV. The procedure and the accuracy of the measurement
are discussed. The primary proton spectrum is derived from the data by using
the CORSIKA/QGSJET code to compute the local hadron flux as a function of the
primary proton spectrum and to calculate and subtract the heavy nuclei
contribution (basing on direct measurements). Over a wide energy range E_0 =
0.5-50 TeV its best fit is given by a single power law : S(E_0) = (9.8 +- 1.1
+- 1.6(sys)) 10^(-5) (E_0/1000)^(-2.80 +- 0.06) m^(-2) s^(-1) sr^(-1) GeV^(-1).
The validity of the CORSIKA/QGSJET code for such application has been checked
using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the
measured hadron fluxes at the two experimental depths (820 and 1030 g/cm^2
respectively) at better than 10% in the considered energy range.Comment: 16 pages, 9 figures, accepted for publication in Astroparticle
Physic
Measurement of the Abundance of Radioactive ^(10)Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon^(-1) with the Balloon-Borne Instrument Isomax
The Isotope Magnet Experiment (ISOMAX), a balloon-borne superconducting magnet spectrometer, was designed to measure the isotopic composition of the light isotopes (3 †Z †8) of cosmic radiation up to 4 GeV nucleon^(-1) with a mass resolution of better than 0.25 amu by using the velocity versus rigidity technique. To achieve this stringent mass resolution, ISOMAX was composed of three major detector systems: a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system, and two silica-aerogel Cerenkov counters for velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive ^(10)Be with respect to its stable neighbor isotope ^9Be, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on 1998 August 4â5 from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g cm^(-2). The isotopic ratio at the top of the atmosphere for 10Be/9Be was measured to be 0:195 ± 0:036 (statistical) ± 0:039 (systematic) between 0.26 and 1.03 GeV nucleon^(-1) and 0:317 ± 0:109 (statistical) ± 0:042 (systematic) between 1.13 and 2.03 GeV nucleon^(-1). This is the first measurement of its kind above 1 GeV nucleon^(-1). ISOMAX results tend to be higher than predictions from current propagation models. In addition to the beryllium results, we report the isotopic ratios of neighboring lithium and boron in the energy range of the time-of-flight system (up to ~1 GeV nucleon^(-1)). The lithium and boron ratios agree well with existing data and model predictions at similar energies
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