G.I. Smirnov

A comparison of the structure functions F2 of the proton and the neutron from deep inelastic muon scattering at high Q2

Abstract High statistics data on the structure functions F2 of the proton and the deutron measured with the same apparatus in deep inelastic muon scattering are used to study the ratio of structure functions of neutron and proton F2n/F2p and their difference F2p-F2n. Both measurements are consistent with predictions of the quark-parton model and of QCD.

On the universality of the x and A dependence of the EMC effect and its relation to parton distributions in nuclei

Abstract It is shown that the latest results from the NMC (CERN) and E665 (Fermilab) groups on F 2 a (x) F 2 d (x) obtained in the shadowing region bring new evidence of the universal A dependence of distortions made in a free-nucleon structure function by a nuclear medium. The observed universality implies that one can consider separately hard ( A ≤ 4) and soft ( A > 4) parton distribution distortions. Soft distortions, which result in differencies between the deep-inelastic scattering cross-sections for nuclei with masses A 1 , A 2 ≥ 4, can be explained as a consequence of the nuclear density variation, independent of x in the range 0.001 ≤ x ≤ 0.7. It is found that nuclear shadowing begins at x 1 = 0.0615 ± 0.0024, independent of A , which is consistent with models that allow for three-parton recombination processes.

An upgraded configuration of a high-luminosity spectrometer for deep-inelastic muon scattering experiments

Abstract A large toroidal iron spectrometer for the study of deep-inelastic muon scattering at the CERN SPS has been upgraded to extend the accessible kinematic range and to reduce the systematic errors on absolute cross-section measurements. The layout of the improved apparatus, the construction of new detectors and associated electronics, and the structure of a new data-acquisition system are described in detail.

Evolution of the nucleon structure in the lightest nuclei

The evolution of the nucleon structure as a function of atomic mass A is considered for the first time for the lightest nuclei, D, 3H, 3He and 4He, with an approach based on the Bethe-Salpeter formalism. We show that the pattern of the oscillation of the structure functions ratio r^A(x) = F_2^A/F_2^N(D) varies with A by changing the position of the cross-over point x_3 in which r^A(x) = 1, unlike the pattern for nuclei with masses A larger than 4, where only the amplitude of the oscillation changes. In particular we find that the pattern of F_2(x) modifications is controlled with the values (1 - x_3) = 0.32 (D/N), 0.16 (3He/D) and 0.08 (4He/D). The obtained results follow from the relativistic consideration of the nuclear structure and allow us to define a whole class of modifications of the partonic distributions in the nucleon bound in a nucleus. The EMC effect is explained as a particular case of the considered class.Abstract We show that the pattern of the oscillation of the structure functions ratio r A ( x )= F 2 A / F 2 N(D) varies with A by changing the position of the cross-over point x 3 in which r A ( x )=1, unlike the pattern for nuclei with masses A >4, where only the amplitude of the oscillation changes. In particular we find that the pattern of F 2 ( x ) modifications is controlled with the values (1− x 3 )=0.32 (D/N), 0.16 ( 3 He/D) and 0.08 ( 4 He/D). The obtained results follow from the relativistic approach and allow one to define the class of modifications of the bound nucleon structure.

Update On the Status of the FLUKA Monte Carlo Transport Code

The FLUKA Monte Carlo transport code is a well-known simulation tool in High Energy Physics. FLUKA is a dynamic tool in the sense that it is being continually updated and improved by the authors. We review the progress achieved since the last CHEP Conference on the physics models, some technical improvements to the code and some recent applications. From the point of view of the physics, improvements have been made with the extension of PEANUT to higher energies for p, n, pi, pbar/nbar and for nbars down to the lowest energies, the addition of the online capability to evolve radioactive products and get subsequent dose rates, upgrading of the treatment of EM interactions with the elimination of the need to separately prepare preprocessed files. A new coherent photon scattering model, an updated treatment of the photo-electric effect, an improved pair production model, new photon cross sections from the LLNL Cullen database have been implemented. In the field of nucleus-- nucleus interactions the electromagnetic dissociation of heavy ions has been added along with the extension of the interaction models for some nuclide pairs to energies below 100 MeV/A using the BME approach, as well as the development of an improved QMD model for intermediate energies. Both DPMJET 2.53 and 3 remain available along with rQMD 2.4 for heavy ion interactions above 100 MeV/A. Technical improvements include the ability to use parentheses in setting up the combinatorial geometry, the introduction of pre-processor directives in the input stream. a new random number generator with full 64 bit randomness, new routines for mathematical special functions (adapted from SLATEC). Finally, work is progressing on the deployment of a user-friendly GUI input interface as well as a CAD-like geometry creation and visualization tool. On the application front, FLUKA has been used to extensively evaluate the potential space radiation effects on astronauts for future deep space missions, the activation dose for beam target areas, dose calculations for radiation therapy as well as being adapted for use in the simulation of events in the ALICE detector at the LHC.