| Understanding the nucleon's spin structure is of great interest to fundamental science. Well aware that quarks, gluons and anti-quarks comprise the nucleon, the scientific community expectation was that the three valence quarks would carry most of the nucleon's spin. However in 1987 the EMC experiment, looking at deep-inelastic scattering, noted that the quarks and anti-quarks could contribute no more than a third to the proton's total spin. This meant that gluons and/or angular momentum must account for the remainder of and majority of the nucleon's spin.;The physics community has now turned to a concerted exploration of the gluon sector with much of the effort concentrated at RHIC. RHIC is the first collider to provide polarized proton on proton collisions. Currently running at s =200 GeV and capable of obtaining s =500 GeV, RHIC and the detectors associated with it, notably STAR and PHENIX, can probe these low x region of the nucleon where a substantial gluon contribution to the total spin could exist.;Measuring the gluon spin contribution to the nucleon, DeltaG, and thereby determining the possible existence and magnitude of an associated orbital momentum, is the highest near term goal of STAR's spin group. In principle several measurements are possible involving the hard scattering of gluons that should give us insight into DeltaG. Currently the channel most accessible to STAR is that of inclusive jets. By comparing the cross section of the jets with respect to the protons spin orientations, we can form the longitudinal double spin asymmetry, ALL, which is expected to be sensitive to the gluon's polarization. In the following years, when RHIC luminosity permits, the cleaner di-jet and gamma-jet channels may be analysed to pin down DeltaG as a function of x.;Typically jets derive from three leader order processes: qq, qg and gg. Jets produced with transverse momentums ranging from 5-15 GeV are most likely to be products of gg or qg reactions, each reaction contributing to the measured asymmetry. This asymmetry must then be extrapolated into a gluon polarization using one of several pQCD models. Here the energy range and inclusiveness of the measurement become problematic. pQCD mandates high energies if one wants precision; most of our data is in the intermediate PT, region where the accuracy of the approximations are not well known. Further, by not selecting out a single channel, processes such as qq contaminate the measurement. To understand the measurement one needs to understand not only how much of the signal is contamination, but also how much of the signal comes from gg interactions and how much from qg interactions, all the while keeping in mind the biases induced by the trigger. That said, inclusive jets are an excellent start to what will provide the best understanding of DeltaG to date. |
