High energy cosmic rays in the low stratosphere and extrapolation above LHC energies

We review the data obtained with the emulsion chambers boarded on Concorde for the events collected above 106 GeV and their specific properties (large multiplicities, multiclusters, coplanar emission): the main features are compared to the expectation of our HDPM2 Monte Carlo collision generator. This multiproduction event generator has been adjusted and tuned, according to the pseudo-rapidity distributions recently observed at √s = 630 GeV, as well as to previous Fermi-lab results at √s = 1800 GeV: an increase of the total inelasticity (0.72 for NSD component) near the knee region and a more important violation than usually expected for Feynman’s scaling in forward region are observed. In such cirumstance, we have simulated large and giant air showers taking into account, in addition, new processes, such as diquark breaking, up to energies exceeding 1020 eV for P.AUGER and EUSO experiments

Compton scattering beyond the impulse approximation

We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the standard IA based formula for the cross section which involves the ground state electron momentum density (EMD) of the initial state. Our formalism will permit the analysis and interpretation of electronic transitions in correlated electron systems via inelastic x-ray scattering (IXS) spectroscopy beyond the constraints of the IA and the IPM.Comment: 7 pages, 1 figur

Large Transverse Momenta in Statistical Models of High Energy Interactions

The creation of particles with large transverse momenta in high energy hadronic collisions is a long standing problem. The transition from small- (soft) to hard- parton scattering `high-pt' events is rather smooth. In this paper we apply the non-extensive statistical framework to calculate transverse momentum distributions of long lived hadrons created at energies from low (sqrt(s)~10 GeV) to the highest energies available in collider experiments (sqrt(s)~2000 GeV). Satisfactory agreement with the experimental data is achieved. The systematic increase of the non-extensivity parameter with energy found can be understood as phenomenological evidence for the increased role of long range correlations in the hadronization process. Predictions concerning the rise of average transverse momenta up to the highest cosmic ray energies are also given and discussed.Comment: 20 pages, 10 figure

3D-electron momentum density of graphite

The complete 3D-electron momentum density (EMD) of solids can be measured by the coincident detection of an inelastically scattered hard X-ray photon and its recoil electron (i.e. a so-called (γ,eγ) experiment). To avoid multiple scattering of the recoil electron the experiment has been performed with a 22 nm thin graphite foil made by laser plasma ablation. The experimental EMD is compared with a pseudopotential calculation. Experiments have been made both at the European Synchrotron Radiation Facility at Grenoble, France, and at the PETRA storage ring of DESY, Hamburg, Germany

3D-electron momentum density of graphite

The complete 3D-electron momentum density (EMD) of solids can be measured by the coincident detection of an inelastically scattered hard X-ray photon and its recoil electron (i.e. a so-called ($\gamma,{\rm e}\gamma$) experiment). To avoid multiple scattering of the recoil electron the experiment has been performed with a 22 nm thin graphite foil made by laser plasma ablation. The experimental EMD is compared with a pseudopotential calculation. Experiments have been made both at the European Synchrotron Radiation Facility at Grenoble, France, and at the PETRA storage ring of DESY, Hamburg, Germany

Electron momentum density of graphite from (γ,eγ\gamma,e\gamma) spectroscopy

By the coincidental detection of an inelastically scattered hard X-ray photon and its recoil electron (i.e. a so-called (γ,eγ) experiment) cuts through the 3D-electron momentum density (EMD) of graphite have been measured and are compared with a theoretical EMD based on a pseudopotential calculation. Peak shifts of the EMD as a function of the electron emission angle are discussed by a detailed consideration of the scattering kinematics. Experiments have been performed at the European Synchrotron Radiation Facility (ESRF) at Grenoble, France

Three-dimensional electron momentum densities:A comparison of (γ,eγ\gamma,e\gamma) and (e,2ee,2e) spectroscopies

We report on the comparison of a (γ,eγ) with an (e,2e) experiment made with the same 17-nm thin graphite foil. The energies of the projectile, scattered projectile, and recoil electron were 174.5, 108.9, and 65.6 keV in the case of the (γ,eγ) experiment and 20, 18.8, and 1.2 keV for the (e,2e) study. In the coincident (e,2e) energy-loss spectra, two distinct peaks are observed which are attributed to σ and π electrons. If the spectral momentum density of the (e,2e) experiment is integrated over the energy loss, the resulting momentum density can be compared directly with the (γ,eγ) result. Good overall agreement is observed between both methods and the resulting three-dimensional electron momentum density is well reproduced by both a pseudopotential and density-functional calculation. The remaining differences between the (e,2e) and (γ,eγ) results are discussed in terms of multiple elastic electron scattering, which might affect the (e,2e) data