SEARCH FOR NEW MASSIVE PARTICLES IN COSMIC-RAYS

In this paper, some unusual cosmic ray events are reviewed. They are t he Yunnan event recorded in 1972 using a cloud chamber at Yunnan Cosmi c Ray Station (YCRS) near Kunming, the south-west of China; the six ex otic events (Kolar events) collected during 1965 to 1975 in the Kolar Gold Mine Field (KGF) in south India; and a double-core event obtained also in KGF in 1979 at a depth different from that where the other si x were obtained, In addition, some interesting phenomena were also not iced: the abnormal upward muon flux observed by the MINI collaboration , and several intriguing signals seen in the proton detector in KGF, A careful kinematics analysis has shown that all these exotic events ar e likely to be related to a kind of heavy and slow-moving (i.e. with a Lorentz factor gamma approximate to 2-5) particles produced from cosm ic ray interactions. Besides, the rough flux estimates in these experi ments seem to indicate that the event rate does not depend on the dept h. Thus a natural hypothesis is that there is a heavy and neutral comp onent in the cosmic rays which might be related with the long-sought w eakly interacting massive particle (WIMP) - one of the most promising candidates of the dark matter of our Universe. Moreover, from the trac ks seen in these events, there is also a signal of the possible existe nce of a kind of heavy and charged particles with a relatively long li fetime (say, longer than 10(-9) s) which might be the interacting prod ucts of the unknown cosmic ray particles mentioned above. We then turn to the question of how to search for these exotic particles in cosmic rays, and propose to build a dedicated magnetic spectrometer for iden tifying them.