First results of the ARGO-YBJ experiment operated in Scaler Mode

experiment is to operate in the field of High Energy Cosmic Ray Physics with an energy threshold of a few hundreds of GeV, performing a detailed imaging of the shower disk. This is obtained with both a high altitude location (in Tibet, P.R. China, at 4300 m a.s.l.) and a large area full coverage (6700 m2) and high granularity detector. The experiment is working in both ”shower mode ” and ”scaler mode”, the latter consisting in recording the detector counting rates from singles to four-fold coincidences in a fixed time window of 500 ms. This technique does not allow the measurement of the arrival direction of each primary, due to the limited number of particles per shower, but gives the possibility to reach the lowest energy limit of the detector (E> 1 GeV) and to study the temporal behaviour of the high energy emission of transient phenomena in coincidence with satellite or ground measurements, mostly operating at lower energies. A large fraction of the detector is in data taking and the first results on the search for GRBs are presented. I