  Even though Pulsar Timing Arrays already have the potential to detect the
gravitational wave background by finding a quadrupole correlation in the timing
residuals, this goal has not yet been achieved. Motivated by some theoretical
arguments, we analyzed some advantages of including the millisecond pulsars
within globular clusters, especially those in their cores, in current and
future Pulsar Timing Array projects for detecting the gravitational waves
emitted by an ensemble of supermassive black holes.
