M. Amenomori et al., Measurement of air shower cores to study the cosmic ray composition in theknee energy region - art. no. 072007, PHYS REV D, 6207(7), 2000, pp. 2007
Since 1996, a hybrid experiment consisting of an emulsion chamber and a bur
st detector array and the Tibet-II air-shower array has been operated at Ya
ngbajing (4300 m above sea level) in Tibet. This experiment can detect air
shower cores, called burst events, accompanied by air showers in excess of
about 100 TeV. Using the burst event data observed by this experiment, we d
iscuss the primary cosmic ray composition around the knee in comparison wit
h the Monte Carlo simulations. In this paper, we show that all the features
of burst events are wholly compatible with the heavy enriched composition
in the knee energy region.