Measurements of inclusive A production with large χF at the collider

We report results of inclusive measurements of A, produced in the forward direction at the with √s = 630 GeV, using the UA8 small angle Roman Pot spectrometers. These measurements cover the range in Feynman-χF and transverse momentum, 0.6 < χF < 1.0 and 0.4 < pt < 0.7 GeV, respectively. Within a systematic uncertainty of ±20% on the absolute cross section measurements, the results are indistinguishable from those made by some of us in two earliar experiments at the CERN Intersecting Storage Rings, with energies, √s = 53 and 62 GeV. In the χF-range, 0.6−0.9, the absolute cross sections are lower by a factor of 2 to 3 than the predictions of the Lund model as embodied in the PYTHIA 5.6 and JETSET 7.3 Monte Carlo programs, indicating inadequacies in knowledge of the baryon fragmentation function. For the largest χF-range, 0.9−1.0, the measurements agree with the Monte Carlo predictions. We have measured the average A polarization for our events and find (6±12%), consistent with previous measurements at the ISR in the present region of χF−pt.