[Show abstract][Hide abstract] ABSTRACT: This paper reports observations of the absolute momentum differential fluxes of negative pions and muons between 4 and 15 GeV/c and between 0.3 and 15 GeV/c, respectively, at an atmospheric depth of 5 g . The data have been collected by the balloon-borne experiment MASS (matter - antimatter space spectrometer) launched from Prince Albert (Canada) where the geomagnetic cut-off is 650 MV/c. The instrument was flown on the 5th of September 1989, the duration of the flight was 5.5 hours at an altitude of more than 117 000 ft. The measured fluxes are compared to calculations. The muon spectrum follows a power law in momentum with a spectral index of 2.36 above 2 GeV/c.
Full-text · Article · Dec 1998 · Journal of Physics G Nuclear and Particle Physics
[Show abstract][Hide abstract] ABSTRACT: Using a superconducting magnet spectrometer, we have measured the energy spectra of electrons, positrons, and protons at ground level at an atmospheric depth of 945 g/cm(2). The differential energy spectrum of the electron component has been determined in the momentum interval between 0.1 and 2.0 GeV/c. This spectrum can be described by two power laws, one below 600 MeV with a spectral index of -1.8 +/- 0.1 and the other above this energy with an index of -2.9 +/- 0.2. The absolute flux values measured here are not in agreement with the earlier results. The fraction of positrons varies from a value of 0.45 at 200 MeV to about 0.5 above 1 GeV, which is consistent with the theoretical expectation. The momentum dependence of the e/mu ratio in the region between 0.25 and 2.0 GeV/c is proportional to p(-2.2), and it appears that the soft component of the ionizing radiation might dominate at ground level at kinetic energies below about 70 MeV. The proton energy spectrum has been determined as a power law in kinetic energy between 2.9 and 19.1 GeV with a spectral index of -2.66 +/- 0.26. The p/mu ratio obtained from this experiment seems to have a steeper momentum dependence than from previous experiments.
Full-text · Article · Dec 1995 · Journal of Geophysical Research Atmospheres
[Show abstract][Hide abstract] ABSTRACT: A ballon-borne magnet spectrometer system was flown for 5.5 hr at an
altitude of more than 117,00 feet from Prince Albert, Saskatchewan
(Canada), on 1989 September 5, when the Newark neutron monitor rate was
2952. The instrument was a modified version of the one used to observe
antiprotons in 1979. The most significant modification was the addition
of an imaging calorimeter, 7.33 radiation lengths thick. Inclusion of
the calorimeter has significantly improved the ability to distinguish
electrons and positrons from the other constituents of the cosmic rays.
The absolute electron flux has been determined in the energy interval
1.3-26 GeV. The electron spectrum at the top of the atmosphere was found
to be Je- = 177E-(3.15+/-0.13) electrons/ sq m/(sr
s GeV) in the energy range 4.0-26 GeV. Below 4 GeV, the spectrum showed
flattening, which is consistent with the effect of solar modulation. The
e(+)/(e(+)+e(-)) ratio was found to be (0.11 +/- 0.03) in the energy
range 5.2-13 GeV.
Full-text · Article · Nov 1994 · The Astrophysical Journal
[Show abstract][Hide abstract] ABSTRACT: This report presents the results obtained with a prototype silicon-tungsten (Si-W) electromagnetic calorimeter, conceived as a fine-grained imaging device to carry out studies of the antimatter component in primary cosmic radiation. The calorimeter prototype contains 20 x, y sampling layers interleaved with 19 showering material planes. One sensitive layer is obtained with two silicon strip detectors (Si-D) (60 × 60) mm2, each divided into 16 strips, 3.6 mm wide; the two detectors are assembled back to back with perpendicular strips. This allows the transverse distributions of the shower in both coordinates at each sampling (0.5 X0) to be pictured. The basic characteristics of the design and the experimental results obtained on a test beam at the CERN proton synchrotron (PS) for electrons and pions are reported. The main results presented are the response of the calorimeter to the electron at various energies (1-7 GeV), and the transverse shower profiles at different calorimeter depths as well as the patterns of the electromagnetic shower and those of the interacting and non-interacting pions. The capability of the calorimeter in measuring the direction of the incoming electromagnetic particle from the pattern of the shower has been evaluated at different energies. These results are encouraging in view of the possible use of this detector to search for high-energy gamma sources in space.
Full-text · Article · Sep 1993 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The silicon sampling calorimeter presented is conceived as a fine grained imaging device to carry out studies of the anti-matter component in the primary cosmic radiation; it will be used in balloon payload program starting in 1993. The first sampling layer (48×48 cm2) of this silicon calorimeter has been completed and successfully tested. We report the first results form studies performed at the CERN PS t7 beam. The complete calorimeter contains 20 xy sampling layers (strip pitch 3.6 mm) interleaved with 19 showering material planes (tungsten 0.5 X0). This allows to picture the transverse distributions of the shower in both coordinates at each sampling. The outstanding imaging capabilities reflects in high particle identification power. Preliminary results from beam tests performed with antiprotons at 3.5 GeV on a tower prototype of the calorimeter are reported.
Full-text · Article · May 1993 · Nuclear Physics B - Proceedings Supplements
[Show abstract][Hide abstract] ABSTRACT: We have determined the momentum spectrum and charge ratio of muons in the region from 250 MeV/c to 100 GeV/c using a superconducting magnetic spectrometer. The absolute differential spectrum of muons obtained in this experiment at 600 m above sea level is in good agreement with the previous measurements at sea level. The differential spectrum can be represented by a power law with a varying index, which is consistent with zero below 450 MeV/c and steepens to a value of -2.7 +/- 0.1 between 20 and 100 GeV/c. The integral f1ux of muons measured in this experiment span a very large range of momentum and is in excellent agreement with the earlier results. The positive to negative muon ratio appears to be constant in the entire momentum range covered in this experiment within the errors and the mean value is 1.220 +/- 0.044. The absolute momentum spectrum and the charge ratio measured in this experiment are also consistent with the theoretical expectations. This is the only experiment which covers a wide range of nearly three decades in momentum from a very low momentum.
[Show abstract][Hide abstract] ABSTRACT: This paper summarizes the performance characteristics of the balloon-borne magnet spectrometer operated by New Mexico State University's Particle Astrophysics Laboratory. Particular emphasis has been placed on the rigidity resolution, including both random and systematic errors of the magnetic spectrometer system. Measurement of the performance characteristics has been greatly enhanced through the use of an imaging calorimeter as an independent aid in the identification of cosmic rays.
Full-text · Article · Aug 1991 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The MASS-SAT Experiment (Matter-Antimatter Space Spectrometer on SATellite) presented here is conceived to search for an experimental
answer to many open problems related to both Astrophysics and Physics, through the detection of positrons, antiprotons, nuclei
and, overall, antinuclei if they exist. Among these problems there are the hypothesized presence of antigalaxies in the Universe
(the matter-antimatter symmetry problem), the existence of black holes as possible antiproton sources (the Hawking effect),
the existence of photinos as antiproton sources (related to the dark-matter problem), the understanding of the mechanism of
cosmic-ray acceleration in the interstellar medium, the determination of the relative abundancies of isotopes in cosmic rays
and many others. The choice of an orbit expecially appropriate for that (geostationary or polar orbit) as well as the choice
of an apparatus composed only of solid-state detectors and permanent magnets (no gas and no liquid helium on board, avoiding
complexity and the necessity of refilling) make it possible to conceive a long (4–5 years) period of data taking with unprecedented
sensitivity in the low-energy region of the cosmic-ray spectrum. The MASS-SAT experiment shows itself as the prosecution of
the MASS balloon-borne experiment and as the logical complement of the Astromag program on the Space Station Freedom.
No preview · Article · Jul 1990 · Il Nuovo Cimento B
[Show abstract][Hide abstract] ABSTRACT: In this paper the WiZard experiment to be performed at the U.S. Space Station Freedom is presented. The apparatus will operate
at the Astromag facility as a magnetic spectrometer dedicated to the search of primordial antimatter in the cosmic radiation.
Several additional questions in the field of astrophysics and cosmology like solar flares, the galactic anisotropy, spectra
of heavier nuclei (from carbon to iron), gamma-ray astronomy and others will also be investigated with such an apparatus and
are discussed as well. The configuration of the apparatus, its integration and the description of each detector is covered
in detail. Ground and flight operations are described together with discussion on data reduction and analysis. Finally, the
mission planning and the onboard crew operations are also outlined.
In questo articolo viene presentato l’esperimento WiZard che sarà effettuato sulla Stazione Spaziale americana Freedom. L'apparato
funzionerà sulla facility Astromag come uno spettrometro magnetico dedicato alla ricerca di antimateria primordiale nella
radiazione cosmica. Con tale apparato saranno pure indagate, e sono qui discusse, varie altre questioni nel campo dell'astrofisica
e della cosmologia come i solar flares, l'anisotropia galattica, gli spettri di nuclei piú pesanti (dal carbonio al ferro),
l'astronomia a raggi gamma e altro. Si descrive inoltre la configurazione dell'apparato, la sua integrazione e la composizione
di ogni rivelatore e si illustrano pure le operazioni a terra e in volo nonché la riduzione e l'analisi dei dati. Infine,
si delineano la pianificazione della missione e le operazioni a bordo dell'equipaggio.
Full-text · Article · Feb 1990 · Il Nuovo Cimento B