Showing papers by "T. J. Sloan published in 1999"

Diffractive dijet production at HERA

Abstract: Interactions of the type ep → eXY are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct photoproduction and of deep-inelastic scattering with photon virtualities in the range 7.5 < Q 2 < 80 GeV2. Cross sections are presented where Y has mass M Y < 1.6 GeV, the squared four-momentum transferred at the proton vertex satisfies |t| < 1 GeV2 and the two jets each have transverse momentum p T jet > 5 GeV relative to the photon direction in the rest frame of X. Models based on a factorisable diffractive exchange with a gluon dominated structure, evolved to a scale set by the transverse momentum $$\hat p_T $$ of the outgoing partons from the hard interaction, give good descriptions of the data. Exclusive $$q\bar q$$ production, as calculated in perturbative QCD using the squared proton gluon density, represents at most a small fraction of the measured cross section. The compatibility of the data with a breaking of diffractive factorisation due to spectator interactions in resolved photoproduction is investigated.

Carrier lifetimes in heavily irradiated silicon diodes

Abstract: Charge collection efficiencies for both minimum ionising and α-particle illumination have been measured for planar diodes which had been irradiated with fluences up to 3×1014 equivalent 1 MeV neutrons cm−2. These charge collection efficiencies have been fitted with a simple model and the carrier lifetimes extracted. The lifetimes are consistent with extrapolations of previous results at lower fluences. There is evidence of extra complication due to the heavy irradiation.