New measurement of the p-(anti p) total cross section at (radical)S = 1.8 TeV

摘要

A new type of detector capable of reaching very small angles was successfully used in Fermilab E811 in Jan. 1996. It consists of a bundle of 15, 000 scintillating fibers each of 100 (micro)m diameter. The fibers are oriented parallel to the beam and gave a measuring resolution of 38 (micro)m transverse to the beam. In this report the authors analyzed about 50,000 elastics as close as 3 mm from the beam. Simulated data runs show that the total cross section should be obtained to an accuracy of (+)2%. The smallest t-bin used has a background subtraction of (approximately)20%, but for most of the t-bins the background is much smaller and the detection efficiency is over 95%. Very preliminary analysis gives a total cross section of (approximately)71 mb at (radical)s = 1.8 TeV using a luminosity-independent method. This is consistent with the earlier Fermilab E710 result which used a different kind of elastic detector. The rho-value analysis has not yet been completed. A personal interpretation (by Orear) of a slower rise in the total cross section is given at the end.