Jose L Medina

An electronic device that suits space research requirements for ion detection

An electronics system for low-energy cosmic ion detection has been designed and built. This instrument was designed to he shipped onboard a satellite with a mission to detect solar energetic particles (SEP) and to study the anomalous component of cosmic rays. The electronics of the instrument were verified by four functional tests. In the first of these tests, its response to well-known electronic pulses, analogous to those produced in the detectors, was checked. During the second test, the coincidence-anticoincidence performances have been verified. The third test consisted of the calibration of each detector and its corresponding electronics chain with alpha particles from a /sup 241/Am source. All these preliminary tests were carried out in an Alcala University laboratory. The final test was done with nuclear reaction fragments at the VICKSI (Van de Graaff Isochron Cyctotron Kombination fur Schwere Ionen) heavy ion accelerator facility of the Hahn Meitner Institute in Berlin. The trails proved to be successful, with satisfactory results when compared with those achieved by standard nuclear instrumentation.

Low‐energy (<1.6 MeV) particle counting rates and solar magnetic activity: A study of the 1980 anomaly

We present a study of the relation between the solar magnetic activity (centered in sunspots, flares types N and B, and long-duration X class flares) and the counting rates of particles in interplanetary space with energies below 1.6 MeV obtained from the Low-Energy Proton Experiment (DFH-EPAS) onboard International Sun-Earth Explorer spacecraft, during the period 1978–1982. Our study shows that the particle counting rates are neither correlated with sunspots number nor with flares type N, but they are correlated with flares type B and mainly with long-duration X class flares. The origin of the low counting rates of particles detected during the years 1979–1980 is investigated as well. The disappearance of the strongest interplanetary shocks during that period can explain this phenomenon, at least within the energy range studied. The absence of any anomalous behavior in the flares type B and in the long-duration X class flares during this period suggests that this shock behavior can be produced by anomalous conditions of the interplanetary magnetic field during the Suns polar magnetic field reversal.

Muon content of UHE air showers: discrimination method between electromagnetic and hadronic cascades

Results from a detailed Monte Carlo simulation for the muon component of EAS, at mountain altitude (800 g cm-2), generated by vertical gamma -rays, protons, oxygen and iron primary cosmic rays, in the energy range 1012-1016 eV, are provided for muon threshold energies from 0.1 to 100 GeV. In the simulation of the different components of the shower ( mu +or-, e+or-, gamma ...), the CORSIKA (cosmic ray simulator for cascade) code has been used to allow for both, electromagnetic and hadronic interactions. Results on the variation and fluctuation of the total muon number with shower size and primary energy are obtained, as well as longitudinal developments, lateral distributions of low-energy muons in air showers and muon energy spectra. Moreover, analytical expressions are fitted to the muon lateral developments, and muon energy spectra have been parametrized to a log-normal distribution. Apart from their value as new results, they may be used for the design of current studies at mountain altitudes. We also seek to provide relations to interpret the experimental data, for those who do not have detailed simulation calculations available.