scholarly journals Interpretation of Cosmic Ray Composition: the Pathlength Distribution

1981 ◽  
Vol 94 ◽  
pp. 107-108
Author(s):  
R. J. Protheroe ◽  
J. F. Ormes
Keyword(s):  
Chemical Composition ◽  
Interstellar Medium ◽  
Energy Range ◽  
Cross Sections ◽  
Cosmic Ray ◽  
Forthcoming Paper ◽  
Ionization Loss ◽  
Entire Energy Range ◽  
Entire Energy ◽  
Energy Dependent

The chemical composition of cosmic ray nuclei with 3≤Z≤28 between ~100 MeV/nuc and a few hundred GeV/nuc are compared with a consistent set of propagation calculations. These include the effects of spallation (energy-dependent cross sections are used), escape and ionization loss in the interstellar medium and deceleration in the solar cavity. This has enabled a consistent study of the cosmic ray pathlength distribution to be made over this entire energy range. Details of the propagation calculation are left to a forthcoming paper.

Merging beams study of ionization of positive ions by electrons

1972 ◽  
Vol 327 (1570) ◽  
pp. 317-328 ◽  
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Cross Sections ◽  
Atomic Nitrogen ◽  
Efficiency Curve ◽  
Entire Energy Range ◽  
Positive Ions ◽  
Entire Energy ◽  
Product Ions ◽  
Scaling Rule

The technique of beam superposition is employed in the experimental study of ionization of He+, N+ and 0+ by electrons. The electron energy range extends up to 300 eV. The primary and product ions are mass selected. Relative cross-sections for ionization are obtained as a function of the laboratory energy of the electrons. The experimental data for He+ and N+ are quite consistent with published values of the absolute cross-sections for these systems. By using Thomson’s classical scaling rule for isoelectronic systems, the cross-sections for ionization of O+ are calculated from those for ionization of atomic nitrogen. These values, when normalized to the relative ionization efficiency curve obtained experimentally here, show close overlap over the entire energy range.

scholarly journals FDMX: extended X-ray absorption fine structure calculations using the finite difference method

2016 ◽  
Vol 23 (2) ◽  
pp. 551-559 ◽  
Author(s):  
Jay D. Bourke ◽  
Christopher T. Chantler ◽  
Yves Joly
Keyword(s):  
Fine Structure ◽  
Energy Range ◽  
Cross Sections ◽  
Full Potential ◽  
Final State ◽  
X Ray ◽  
Complete Representation ◽  
Absorption Fine ◽  
Energy Dependent ◽  
X Ray Absorption

A new theoretical approach and computational package,FDMX, for general calculations of X-ray absorption fine structure (XAFS) over an extended energy range within a full-potential model is presented. The final-state photoelectron wavefunction is calculated over an energy-dependent spatial mesh, allowing for a complete representation of all scattering paths. The electronic potentials and corresponding wavefunctions are subject to constraints based on physicality and self-consistency, allowing for accurate absorption cross sections in the near-edge region, while higher-energy results are enabled by the implementation of effective Debye–Waller damping and new implementations of second-order lifetime broadening. These include inelastic photoelectron scattering and, for the first time, plasmon excitation coupling. This is the first full-potential package available that can calculate accurate XAFS spectra across a complete energy range within a single framework and without fitted parameters. Example spectra are provided for elemental Sn, rutile TiO2and the FeO6octahedron.

Resonance dipole–Raman scattering at the forbidden yellow exciton in Cu2O

1976 ◽  
Vol 54 (18) ◽  
pp. 1893-1897
Author(s):  
Gayatri Bhattacharya Choudhury ◽  
K. P. Jain
Keyword(s):  
Kinetic Energy ◽  
Dominant Role ◽  
Detailed Knowledge ◽  
Strong Resonance ◽  
Entire Energy Range ◽  
Resonance Enhancement ◽  
Entire Energy ◽  
Energy Dependent ◽  
Entire Spectral Range ◽  
The Continuum

It has been observed by Yu, Shen, Petroff, and Falicov that there is a strong resonance enhancement in the 220 cm−1 Raman line of Cu2O at the Γ12− phonon-assisted absorption threshold of the forbidden 1s yellow exciton. In this paper we present a more complete theory to explain their experimental results over the entire spectral range. The theory includes both the continuum and discrete scattering. It has been shown that away from the resonance the continuum part plays a dominant role. The kinetic energy of the 1s yellow exciton is incorporated into the theory by introducing an energy-dependent lifetime broadening parameter Γ(ω). In the absence of detailed knowledge of the contribution of various phonons to the exciton lifetimes over the entire energy range, we have chosen to work with a phenomenological Γ(ω).

scholarly journals Cosmic Ray Antiprotons 5–12 GeV

1981 ◽  
Vol 94 ◽  
pp. 257-258 ◽  
Author(s):  
T. K. Gaisser ◽  
A. J. Owens ◽  
Gary Steigman
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Cosmic Ray ◽  
Image Position ◽  
Energy Dependent ◽  
Complex Nuclei

Secondary antiprotons are a potentially interesting probe of cosmic ray propagation because their production cross section is strongly energy-dependent, increasing by more than two orders of magnitude between 10 and 1000 GeV/c. This is quite unlike the case for fragmentation cross sections of complex nuclei, which are virtually constant with energy. Moreover, the flux depends primarily on the environment seen by protons which need not be identical to that probed by other nuclei.

Modified Heisenberg's Approach for the Mean Charged Hadron Multiplicity in High Energy Collisions

1978 ◽  
Vol 33 (4) ◽  
pp. 493-497
Author(s):  
D. C. Ghosh ◽  
I. K. Daftari ◽  
D. K. Bhattacharjee ◽  
S. C. Naha ◽  
A. Roy Chowdhury ◽  
...  
Keyword(s):  
Energy Range ◽  
High Energy ◽  
Charged Hadron ◽  
Entire Energy Range ◽  
Hadron Multiplicity ◽  
Entire Energy ◽  
High Energy Collisions ◽  
The Mean ◽  
Hadronic Collisions ◽  
Remarkable Agreement

The semiempirical formulation of Ghosh et al. for the energy dependence of multiplicity in hadronic collisions has been applied to account for the experimental multiplicity data of π±p and K±p collisions. A remarkable agreement has been found over the entire energy range.

Positron–Helium Scattering Cross Sections and Phase Shifts below 19 eV

1973 ◽  
Vol 51 (14) ◽  
pp. 1565-1572 ◽  
Author(s):  
B. Jaduszliwer ◽  
D. A. L. Paul
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Phase Shifts ◽  
S Wave ◽  
Wave Phase ◽  
Entire Energy Range ◽  
Nice Agreement ◽  
Scattering Cross Sections ◽  
D Wave

The total cross sections for elastic scattering of positrons in the energy range from 4 to 19 eV have been measured by the method of transmission. By varying a magnetic field applied along the axis of the scattering chamber the transmitted fraction of the beam is altered, from which individual phase shifts can be extracted. s-, p-, and d-wave phase shifts are given over the entire energy range. The s-wave phase shifts are in agreement with values published by Drachman in 1968, while the p- and d-wave phase shifts are intermediate between values calculated by the same author in 1966 and 1971. The experimental results agree with those of Costello et al., and marginally with our own 1972 results, but are significantly different from those of Canter et al. We compute that the Ramsauer minimum in the diffusion cross section must be 0.04πa02 at 1.6 eV while the minimum in the total cross section is 0.11πa02 at 2.1 eV. The shoulder breadth observed in annihilation experiments is in nice agreement with what one would predict from our phase shifts.

scholarly journals Measurement of the cosmic ray spectrum and chemical composition in the 1015-1018 eV energy range

2018 ◽  
Vol 172 ◽  
pp. 07001 ◽  
Author(s):  
Andrea Chiavassa
Keyword(s):  
Chemical Composition ◽  
Energy Range ◽  
Systematic Error ◽  
Cosmic Ray ◽  
Absolute Calibration ◽  
Particle Spectrum ◽  
Air Showers ◽  
Primary Spectrum ◽  
Mass Calibration ◽  
Event Basis

Cosmic ray in the 1015–1018 eV energy range can only be detected with ground based experiments, sampling Extensive Air Showers (EAS) particles. The interest in this energetic interval is related to the search of the knee of the iron component of cosmic ray and to the study of the transition between galactic and extra-galactic primaries. The energy and mass calibration of these arrays can only be performed with complete EAS simulations as no sources are available for an absolute calibration. The systematic error on the energy assignment can be estimated around 30 ± 10%. The all particle spectrum measured in this energy range is more structured than previously thought, showing some faint features: a hardening slightly above 1016 eV and a steepening below 1017 eV. The studies of the primary chemical composition are quickly evolving towards the measurements of the primary spectra of different mass groups: up to now we are able to separate (on a event by event basis) light and heavy primaries. Above the knee a steepening of the heavy primary spectrum and a hardening of the light ones have been detected.

Sign in / Sign up

Export Citation Format

Share Document