138 Annual Report 1997

REPORTS ON RESEARCH

Extensive Air Showers (EAS) of High Energy Cosmic Rays (CR) PL9900108 7.1 Lodz EAS Array by R.Firkowski, J.Gawin, S.Kowalczyk, S.Pachala, J.Swarzynski, J.Szabelski

The Lodz hodoscopic array for EAS registration was working during 1997. More then 600000 showers were registered. The data from the part of array on the surface of the ground were stored. All the Geiger-Muller tubes in this part of the array have been replaced by new ones. The actual experimental setup allows for the control of the state of the array and correctness of its work. Several programs for testing the work of the array have been written. Due to these programs, we manage to find and remove a few faults in the work of the array. Several programs for storing and reading experimental data have been written, which enable quick access to the data base and fast data analysis.

7.2 KASCADE EAS Experiment by J.Zabierowski

The year 1997 was the first year of routine data taking for KASCADE (Karlsruhe Shower Core and Array Detector) - currently the biggest cosmic ray experiment in Europe, covering primary energy range 1015 - 1017eV and situated in Forschungszentrum Karlsruhe, Germany. The main aim of the KASCADE project [1] is the determination of the chemical composition of cosmic rays in the above mentioned energy range, where the so called, "knee" in the primary cosmic ray spectrum has been observed. This, in turn, will allow us to better understand the origin and propagation mechanisms of cosmic rays. The main advantage of the installation is the simultaneous measurement of a large number of observables for each individual event. This is achieved by a combination of various advanced detection techniques for the electromagnetic, muonic and the hadronic component of the EAS. By the end of 1997, 90% of the Central Calorimeter was in operation and the build-up of the last big component of the experiment the Muon Tunnel - was started. This large muon detector, comprising 600 m2of limited streamer tubes (organised in 16 towers) and more than 25 000 electronics channels, will be brought into full operation during 1998. The design and prototype testing of the tunnel front-end electronics was completed in L6dz during 1997 and after succesful test with one tower [2] its mass production was performed in Germany. The development of the data analysis methods for the tunnel has been in progress. The collaboration activity, in which the Lodz group (from SINS and Lddz University) was participated, was devoted to better understanding of the detectors' performance and development of the analysis procedures which will account for possible systematical errors. Different preliminary spectra and distributions were presented during XXV International Cosmic Ray Conference in Durban (South Africa) in July/August 1997 in 12 contributions (see the publications of our department) and the current status of the experiment was given in the Highlight Talk there [3],

[1] H.O.Klages ,.. J.Wdowczyk, J.Zabierowski et al. Nucl.Phys.B (Proc.Suppl) B52 (1997) 92 [2] I.Atanasov, J.Zabierowski,.., et al. Nucl.Instr. and Methods, in press [3] H.O.Klages for the KASCADE Collaboration, to be published in World Scientific 1998

7.3 EAS of High Energy CR and Nucleus-Nucleus Interactions byLSzabelski PL9900110

The collaboration on the EAS studies with physicists from the Institute of Nuclear Studies of the Russian Academy of Sciences was continued. Joint research was mainly devoted to the analysis of muons of energy above 200 GeV detected underground and to studies of time structure of the front of EAS registered at moutain altitudes.