  The effect of limiting the acceptance in rapidity on event-by-event
multiplicity fluctuations in nucleus-nucleus collisions has been investigated.
Our analysis shows that the multiplicity fluctuations decrease when the
rapidity acceptance is decreased. We explain this trend by assuming that the
probability distribution of the particles in the smaller acceptance window
follows binomial distribution. Following a simple statistical analysis we
conclude that the event-by-event multiplicity fluctuations for full acceptance
are likely to be larger than those observed in the experiments, since the
experiments usually have detectors with limited acceptance. We discuss the
application of our model to simulated data generated using VENUS, a widely used
event generator in heavy-ion collisions. We also discuss the results from our
calculations in presence of dynamical fluctuations and possible observation of
these in the actual data.
