The practical Pomeron for high energy proton collimation

We present a model which describes proton scattering data from ISR to Tevatron energies, and which can be applied to collimation in high energy accelerators, such as the LHC and FCC. Collimators remove beam halo particles, so that they do not impinge on vulnerable regions of the machine, such as the superconducting magnets and the experimental areas. In simulating the effect of the collimator jaws it is crucial to model the scattering of protons at small momentum transfer t, as these protons can subsequently survive several turns of the ring before being lost. At high energies these soft processes are well described by Pomeron exchange models. We study the behaviour of elastic and single-diffractive dissociation cross sections over a wide range of energy, and show that the model can be used as a global description of the wide variety of high energy elastic and diffractive data presently available. In particular it models low mass diffraction dissociation, where a rich resonance structure is present, and thus predicts the differential and integrated cross sections in the kinematical range appropriate to the LHC. We incorporate the physics of this model into the beam tracking code MERLIN and use it to simulate the resulting loss maps of the beam halo lost in the collimators in the LHC

Bose-Einstein correlations in neutrino and anti-neutrino interactions with nucleons

023 auteursinfo:eu-repo/semantics/publishe

Determination of the ratio r(v) = d(v) / u(v) of the valence quark distributions in the proton from neutrino and anti-neutrino reactions on hydrogen and deuterium

Based on a QCD analysis of the parton momentum distributions in the proton, the ratio rv=dv/uv of the d and u valence quark distributions is determined as function of x in the range 0.01<x<0.7. The analysis uses data from neutrino and antineutrino charged current interactions on hydrogen and deuterium, obtained with BEBC in the (anti)neutrino wideband beam of the CERN SPS. Sincev mainly depends on the deuterium/hydrogen ratios of the normalised x-y-Q2-distributions many systematic effects cancel. It is found that rv decreases with increasing x, and drops below the naive SU(6) expectation of 0.5 for x≳0.3. An extrapolation of rv to x=1 is consistent with the hypothesis rv(1)=0. © 1994 Springer-Verlag