[en] We perform a detailed analysis on the scaling properties of the total γ^* p cross section, σ_γ^*_p. We write the cross section as a product of two functions W and V representing, respectively, the dynamical degrees of freedom and the contribution from the valence partons. Analyzing data from HERA and fixed target experiments, we find that V is independent of Q² and concentrated at large x, while W carries all the information on the Q² evolution of σ_γ^*_p. We define the reduced cross section σ_γ^*_p = W = σ_γ^*_p/V, and show that it is very close to a generalized homogeneous function. This property gives rise to geometric scaling for σ_γ^*_p, and it also explains the known geometric scaling of σ_γ^*_p at low x. As a consequence of our Ansatz, we also obtain a compact parameterization of a σ_γ^*_p describing all data above Q² = 1 GeV². (Author)

[en] Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron collider delivered 12 fb⁻¹ of pp^¯ collisions at √(s)=1.96TeV to the Collider Detector at Fermilab (CDF). During that time, the CDF silicon vertex detector was subject to radiation doses of up to 12 Mrad. After the end of operations, the silicon detector was annealed for 24 days at 18 °C. In this paper, we present a measurement of the change in the bias currents for a subset of sensors during the annealing period. We also introduce a novel method for monitoring the depletion voltage throughout the annealing period. The observed bias current evolution can be characterized by a falling exponential term with time constant τ_I=17.88±0.36(stat.)±0.25(syst.) days. We observe an average decrease of (27±3)% in the depletion voltage, whose evolution can similarly be described by an exponential time constant of τ_V=6.21±0.21days. These results are consistent with the Hamburg model within the measurement uncertainties

[en] The total cross section for the photoproduction process with a leading proton in the final state has been measured at γp centre-of-mass energies W of 91, 181 and 231 GeV. The measured cross sections apply to the kinematic range with the transverse momentum of the scattered proton restricted to p_T≤0.2 GeV and 0.68≤z≤0.88, where z=E_p'/E_p is the scattered proton energy normalised to the beam energy. The cross section dσ_γp→Xp'(W,z)/dz is observed to be independent of W and z within the measurement errors and amounts to (8.05±0.06 (stat)±0.89 (syst)) μb on average. The data are well described by a Triple Regge model in which the process is mediated by a mixture of exchanges with an effective Regge trajectory of intercept α_i(0)=0.33±0.04 (stat)±0.04 (syst). The total cross section for the interaction of the photon with this mixture (γα_i→X) can be described by an effective trajectory of intercept α_k(0)=0.99±0.01 (stat)±0.05 (syst). Predictions based on previous triple Regge analyses of pp→pX data assuming vertex factorisation are broadly consistent with the γp data. The measured cross sections are compared with deep inelastic scattering leading proton data in the same region of z and p_T for photon virtuality Q²>2.5 GeV². The ratio of the cross section for leading proton production to the total cross section is found to rise with Q²