[en] The validity of Koba-Nielsen-Olesen scaling hypothesis was examined in the case of heavy, black, and grey prongs in proton-emulsion collisions ('heavy' means 'either black or grey'). The average multiplicities of these prongs were computed in the region 0.1-400 GeV for the nuclei C, N, O, S, Br, Ag, and I. After the inclusion of the energy-dependent excitation probability of the nuclei of the form P* = b₀ + b₁ ln E₀ into the model, experimental multiplicity distributions in the energy region 6-300 GeV agreed satisfactorily with the scaling hypothesis. The ratio of the dispersion D (D = √< n²>-< n>²) to the average multiplicity < n> in the scaling functions of heavy, balck, and grey prongs was estimated to be 0.86, 0.84, and 1.04, respectively, in the high energy region. (Auth.)

[en] Contribution of geomagnetic effects to the diurnal cosmic ray variation has been calculated. Daily variations in the directions of approach and in the acceptance cones are taken into account. In the estimation, the trajectory tracing method is used. The model used for the geomagnetic field is a combination of the dipole field and of the external field given by Olson and Pfitzer

[en] The energy spectrum of cosmic-ray hadrons was measured in the energy region 0.5 GeV-500 GeV. The result is based on the frequency data of various multiplicities in the neutron monitor in Turku, Finland, and on the predictions of hadron cascades by using a Monte-Carlo method. (author)

[en] Interplanetary (IP) shock passages are usually identified by abrupt changes in the plasma parameters, but sometimes they are also associated with energetic storm particles (ESPs). The maximum observed energies of ESPs usually reach a few MeVs per nucleon and occasionally even a few hundred MeVs per nucleon. We have carried out a statistical study of ESP events observed by SOHO/ERNE above 1.5 MeV during the seven-year period between May 1996 and April 2003. In the first stage, we gathered a comprehensive database of IP shock candidates using several ready-made shock lists. We defined a qualitative classification for the ESP signals and studied their association with fast forward shocks. We present a survey of the overall statistics of ESP associations with fast forward shocks and the yearly amount of the shocks and associated ESP events during the 7-year study period. Our most important findings are that only 40% of the observed interplanetary fast forward shocks accelerate ESPs to energies greater than 1.5 MeV and that the high-energy ESP-effectiveness of the fast forward shocks has a solar cycle dependence. The yearly ESP-effectiveness varied from 11%, in May 1996-April 1997 (∝activity minimum), to 53% in May 2000-April 2001 (∝activity maximum). We also performed a quantitative analysis of the proton power law spectra at the time of the shock passage. We found that the average spectral index of ESPs was -3.6 with the standard deviation of the distribution of 1.3. The ESP events had significantly larger power law factors than the reference spectra, calculated every day at a certain time for comparison. (orig.)

[en] Particle fluxes and pitch angle distributions of relativistic solar protons at 1 AU were determined by Monte Carlo calculations. The analysis covers two hours after the release of the particles from the Sun and total of eight 100000 particle trajectories were simulated. The pitch angle scattering was assumed to be isotropic and the scattering mean free path was varied from 0.1 to 4 AU. As an application, the solar injection time and interplanetary scattering mean free path of particles that gave rise to the GLE on May, 1978 were determined. Assuming exponential form, the injection decay time was found to be about 11 minutes. The m.f.p. of pitch angle scattering during the event was about 1 AU

[en] An experimental arrangement for studying multiple hadrons produced in high-energy hadron-nucleus interactions is under construction at the university of Turku. The method of investigation is based on the detection of hadrons arriving simultaneously at sea level over an area of a few square metres. The apparatus consists of a hadron spectrometer with position-sensitive detectors in connection with a small air shower array. The position resolution using streamer tube detectors will be about 10 mm. Energy spectra of hadrons or groups of simultaneous hadrons produced at primary energies below 10 to the 16th power eV can be measured in the energy range 1 to 2000 GeV

[en] Modulation of the cosmic-ray energy spectrum was studied by using the Turku double neutron monitor. The multiplicity region of detected neutrons produced by cosmic ray hadrons in the monitor was divided into seven categories corresponding to mean energies 0.1, 0.3, 1.0, 3.2, 8.6, 21, and 94 GeV of hadrons at sea level. Based on 24-hour frequencies, a statistical analysis showed that modulation of the intensity in all categories occurred during several periods in the fall 1984. The magnitude of the variation was a few per cent

[en] A double neutron monitor consisting of two neutron monitors, one on top of the other, has been constructed. A thick layer of moderating material between the monitors enables two separate independent measurements of multiplicity. The total thickness of the production layer in the double monitor is approximately 3 interaction mean free paths of high-energy hadrons in lead. A brief discussion of the characteristics of the monitor is given

[en] The maximum entropy method has been applied in the spectral analysis of high-energy cosmic-ray intensity during the large Forbush event of July 13, 1982. An oscillation with period of about 2 hours and amplitude of 1 to 3% was found to be present during the decrease phase. This oscillation can be related to a similar periodicity in the magnetospheric field. However, the variation was not observed at all neutron monitor stations. In the beginning of the recovery phase, the intensity oscillated with a period of about 10 hours and amplitude of 3%

[en] A fast databuffer system was constructed, in which cosmic ray events in the Turku hadron spectrometer, including particle arrival times, are recorded with time resolution of 100 ns. The databuffer can be read continuously by a microprocessor, which preanalyzes the data and transfers it to the main computer. The time span that can be analyzed in every detail, is a few seconds. The high time resolution enables a study of time correlated groups of high energy particles. In addition the operational characteristics of the spectrometer can be monitored in detail