  We consider pair production of new down-type isosinglet quarks originating
from E_{6}, which is the favorite gauge symmetry group in superstring inspired
GUT models. The study concentrates on the possibility of observing the pair
production of the lightest of the new quarks, D, in the ATLAS detector at the
forthcoming LHC accelerator, in the channel D\bar{D}\to ZjZj . Both signal and
background events are studied using tree level event generators based on Monte
Carlo techniques. The detector effects are taken into account using the ATLAS
fast simulation tool, ATLFAST. It is shown that ATLAS can observe the D quark
within the first year of low luminosity LHC operation if its mass is less than
650 GeV. For the case of two years of full luminosity running, 1 TeV can be
reached with about three sigma significance.
