[en] We have analysed muons and multimuons measured with the Frejus underground detector in order to find evidence for high energetic cosmic rays pointing to the binary system Cygnus X-3. The Frejus detector is under operation from February 1984. In this talk we present data recorded till December 1986. No evidence for a positive excess of muons from the direction of Cygnus X-3 and no signal in the phase diagrams can be claimed. The 90% C.L. upper flux limit turns out to be 5 x 10^-13 cm^-2 s^-1

[en] The Frejus detector is a fine grained iron calorimeter originally designed to find evidence for nucleon decay. We observed (83 fully contained - and 41 semi contained events with a visible energy greater than 200 MeV corresponding to a sensitivity of 0.882 kton-years (kty) (fiducial mass x lifetime). From our simulations using the atmospheric ν-flux calculations we expect 143 events:kty which is in remarkable agreement with the measured number of 124 events/0.882 kty. Analysing these events searching for nucleon decay we found 1 candidate with a charged lepton in the final state and 1 candidate in the channel n → antiν + π⁰. Carefully ν-background estimations with a ν-simulation procedure and with the reanalysis of the Aachen-Padova experiment yield a background expectation of 0.2 events/0.88 kty (for the charged lepton candidate) and 1 event/ 0.88 kty (for n → antiν + π⁰)

[en] EPCQU is a Monte-Carlo event generator for the wide-angle Bremsstrahlung reaction e + p → γ + X. This reaction is the most important background source of an excited electron which could be produced in ep-collisions and which decays into an electron and photon. Experimentally, both electron and photon should be detected inside operating detectors. (orig.)

[en] The Frejus underground detector has been operating since February 1984. With this detector we have analyzed muons and multimuons which were detected till January 1986 in order to search for high energetic cosmic ray muons pointing to Cygnus X-3. This yields a 90 % Confidence level upper flux limit of 0.8.10-1₂ cm^-2 s^-1, for an average rock overburden of 5000 hg cm^-2

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[en] We discuss the production of new heavy fermions and excited fermions (mostly neutrinos) at HERA. After a short theoretical introduction specific models are simulated in the H1 detector. Exclusion limits for an integrated luminosity of 100 pb^-1 are given. (orig.)

[en] The status of the Frejus experiment and the preliminary results obtained in the search for nucleon decay are discussed. A modular, fine grain tracking calorimeter was installed in the Frejus laboratory in the period extending from October 1983 to May 1985. The 3300 cubic meter underground laboratory, located in the center of the Frejus tunnel in the Alps, is covered in the vertical direction by 1600 m of rocks (4400 m w.e.). The average number of atmospheric muons in the lab is 4.2 square meters per day. The 912 ton detector is made of 114 modules, each one including eight flash chamber and one Geiger vertical planes of (6 x 6) square meters dimensions. The flash chamber (and Geiger) planes are alternatively crossed to provide a 90 deg. stereo reconstruction. No candidate for the nucleon decay into charged lepton is found in the first sample of events

[en] Very quickly after the beginning of these experiments it became evident that the decay p → eπ⁰ could not be observed with such low detector masses. This led to larger detectors and in addition to several improvements of the existing detectors. Todate the lower limits of the mode p → e⁺π⁰ and p → anti νK⁺ reached 5.9x10³² years and 1x10³² years, respectively. SU₅ seems to be ruled out and also the SUSY preferred channel reached a value which is difficult to improve significantly in the near future with current experiments. (orig./HSI)