The energy dependence of angular correlations inferred from mean fluctuation scale dependence in heavy ion collisions at the SPS and RHIC

We present the first study of the energy dependence of pt angular correlations inferred from event-wisemean transversemomentum <p(t)> fluctuations in heavy ion collisions. We compare our large-acceptance measurements at CM energies root s(NN) = 19.6, 62.4, 130 and 200 GeV to SPS measurements at 12.3 and 17.3 GeV. p(t) angular correlation structure suggests that the principal source of pt correlations and fluctuations is minijets (minimum-bias parton fragments). We observe a dramatic increase in correlations and fluctuations from SPS to RHIC energies, increasing linearly with 1n root s(NN) from the onset of observable jet-related <p(t)> fluctuations near 10 GeV.