[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

[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] 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] We have recently started a systematic study of short-period (periods less than 60 min) variations in the cosmic-ray intensity. By making use of the MEM, we have found intensity oscillations with periods varying from 16 to 27 minutes during the GLE on February 16, 1984

[en] The energy spectra of cosmic-ray neutrons, protons, and pions were determined at sea level in the range 0.1 - 1000 GeV. The results are based on the measurements of the neutron-multiplicity distributions produced by cosmic hadrons in the Turku spectrometer. Below 0.5 GeV, the values gamma 1.47 + or - 0.04 and 0.8 + or - 0.1 were obtained for the slopes of the neutron and proton spectra. At 1000 GeV, the nucleon spectra are much steeper with gamma 2.79 + or 0.06. The pion spectrum was found to obey the power law with gamma 1.41 + or - 0.05 in the low-energy region up to 30 GeV. Above 500 GeV, the spectrum of pions, containing an admixture of accompanied particles, was found to reach the high energy limit with gamma 2.92 + or - 0.06. 7 references

[en] ERNE is designed to study the composition and energy spectra of particles encountered in interplanetary space in the energy range from 1 MeV/n to well beyond 500 MeV/n. Several innovative ideas had to be incorporated in the design of the instrument in order to fulfill the scientific requirements. Position-sensitive strip detectors are used in the high energy detector (HED) for determining particle trajectories. Integrated interstrip capacitances were designed to allow for a very simple read-out technique from the two edges of each detector. The event recognition, signal multiplexing and control of the pulse height analysis are based on a gate array technique. The versatility of the gate array also allowed an elegant realization of a number of other functions and instrument control tasks. By using the gate array a very compact structure of the digital control electronics was achieved. (orig.)

[en] Designed to be launched by Soho spacecraft, ERNE sensor unit is made of a LED (Low Energy Detector) and a HED (High Energy Detector). Both devices are described. Then the test and calibration are reported. (D.L.). 4 figs

[en] The energy spectrum of cosmic-ray hadrons between 10 GeV and 10 TeV at sea level was calculated by using a Monte-Carlo method. The results show a strong steepening of the hadron spectrum at about 200 GeV. The change in the spectral slope is interpreted as a combined effect due to the energy-dependent production cross section of hadron-air-nucleus collisions and the saturation of the relative intensity of pions in the hadron family. The magnitude of the change is found to vary from 0.5 to 0.7 depending on the form of the production cross section. The results agree with the experimental spectra obtained by the Turku double neutron monitor. (author)