Cosmic-ray elemental abundances from 1 to 10 GeV per AMU for boron through nickel

1987 ◽  
Vol 322 ◽  
pp. 981 ◽  
Author(s):  
Robert Dwyer ◽  
Peter Meyer
Keyword(s):  
Cosmic Ray ◽  
Elemental Abundances

scholarly journals A Model of the Chemistry in the Neutral Shell of a Planetary Nebula

1993 ◽  
Vol 155 ◽  
pp. 221-221
Author(s):  
S. N. Gouldsworthy ◽  
D. R. Flower
Keyword(s):  
Planetary Nebula ◽  
Chemical Species ◽  
Cosmic Ray ◽  
Large Set ◽  
Spectral Emission ◽  
Two Photon ◽  
Elemental Abundances ◽  
Cosmic Ray Interactions ◽  
Planck Spectrum ◽  
Region Data

A model of the neutral region of a planetary nebula has been constructed, building on an existing program (Abgrall et al. 1992, Astr. Astrophys. 253, 525). It incorporates a large set of equations governing the formation and destruction of molecular species and also covers photo-dissociation/ionization reactions and cosmic ray interactions. The radiation field impinging on the nebula is modelled as a 105 K diluted Planck spectrum, truncated below 91.2 nm, augmented by spectral emission lines from the ionized region (data from G. Stasinska, private communication) and the hydrogen (2s→1s) two-photon continuum. The chemical species involved in the reactions are composed of seven elements — H, He, C, O, N, S and Fe — with H and He dominating the elemental abundances. The model considers a chemical environment which is carbon-rich (i.e. C/O > 1).

THE ATTENUATION LENGTH OF COSMIC RAY IRON IN THE ATMOSPHERE OBTAINED BY TIGER EXPERIMENT

2005 ◽  
Vol 20 (29) ◽  
pp. 6702-6704
Author(s):  
S. KODAIRA ◽  
M. HAREYAMA ◽  
N. HASEBE ◽  
T. MIYACHI ◽  
K. SAKURAI ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Precise Measurement ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Attenuation Length ◽  
Flight Data ◽  
Elemental Abundances ◽  
Balloon Experiment ◽  
Path Lengths ◽  
Balloon Measurements

A precise measurement of elemental abundances of galactic cosmic rays from charges Z = 20 to 34 was made by TIGER balloon experiment. Using the various path lengths in the atmosphere between 4 and 16 g/cm2 from the TIGER flight data, we derived the attenuation length of iron nuclei with the energy above 2.5 GeV/n in the atmosphere. As the result, we obtained the attenuation length of 15.5 ± 0.6 g/cm 2 which is consistent with previous results of balloon measurements.

Cosmic-ray elemental abundances

1984 ◽  
Vol 4 (2-3) ◽  
pp. 5-14 ◽  
Author(s):  
Niels Lund
Keyword(s):  
Cosmic Ray ◽  
Elemental Abundances

scholarly journals Tracers of the ionization fraction in dense and translucent gas

2020 ◽  
Vol 645 ◽  
pp. A28
Author(s):  
Emeric Bron ◽  
Evelyne Roueff ◽  
Maryvonne Gerin ◽  
Jérôme Pety ◽  
Pierre Gratier ◽  
...  
Keyword(s):  
Predictive Power ◽  
Cosmic Ray ◽  
Dense Medium ◽  
Large Field ◽  
Giant Molecular Clouds ◽  
Elemental Abundances ◽  
Dense Cores ◽  
Chemical Models ◽  
Automated Method ◽  
Ionization Fraction

Context. The ionization fraction in the neutral interstellar medium (ISM) plays a key role in the physics and chemistry of the ISM, from controlling the coupling of the gas to the magnetic field to allowing fast ion-neutral reactions that drive interstellar chemistry. Most estimations of the ionization fraction have relied on deuterated species such as DCO+, whose detection is limited to dense cores representing an extremely small fraction of the volume of the giant molecular clouds that they are part of. As large field-of-view hyperspectral maps become available, new tracers may be found. The growth of observational datasets is paralleled by the growth of massive modeling datasets and new methods need to be devised to exploit the wealth of information they contain. Aims. We search for the best observable tracers of the ionization fraction based on a grid of astrochemical models, with the broader aim of finding a general automated method applicable to searching for tracers of any unobservable quantity based on grids of models. Methods. We built grids of models that randomly sample a large range of physical conditions (unobservable quantities such as gas density, temperature, elemental abundances, etc.) and computed the corresponding observables (line intensities, column densities) and the ionization fraction. We estimated the predictive power of each potential tracer by training a random forest model to predict the ionization fraction from that tracer, based on these model grids. Results. In both translucent medium and cold dense medium conditions, we found several observable tracers with very good predictive power for the ionization fraction. Many tracers in cold dense medium conditions are found to be better and more widely applicable than the traditional DCO+/HCO+ ratio. We also provide simpler analytical fits for estimating the ionization fraction from the best tracers, and for estimating the associated uncertainties. We discuss the limitations of the present study and select a few recommended tracers in both types of conditions. Conclusions. The method presented here is very general and can be applied to the measurement of any other quantity of interest (cosmic ray flux, elemental abundances, etc.) from any type of model (PDR models, time-dependent chemical models, etc.).

The charge distribution of the energetic very heavy nuclei in the primary cosmic radiation

1968 ◽  
Vol 46 (10) ◽  
pp. S583-S587 ◽  
Author(s):  
O. Mathiesen ◽  
C. E. Long ◽  
P. S. Freier ◽  
C. J. Waddington
Keyword(s):  
Charge Distribution ◽  
Cosmic Radiation ◽  
Cosmic Ray ◽  
Charge Composition ◽  
Heavy Nuclei ◽  
Elemental Abundances ◽  
Residual Atmosphere ◽  
Primary Cosmic Radiation ◽  
Initial Acceleration ◽  
The Individual

A fully digitized, semiautomated photodensitometer has been employed to study the detailed charge composition of primary cosmic-ray nuclei having [Formula: see text] detected in a stack of nuclear emulsions flown from Hyderabad, India under approximately 4 g/cm2 of residual atmosphere. One hundred and twenty nuclei heavier than phosphorus have been analyzed. These nuclei all had energies exceeding 7.1 GeV per nucleon and have had their charges measured with an accuracy estimated to be ± 0.4 of a unit charge. It has consequently been possible to resolve the individual charges and to determine the elemental abundances. The observed charge distribution has been corrected to the top of the atmosphere and compared with various cosmological abundance compilations. After deriving values for the fragmentation parameters in hydrogen, it is concluded that the data are consistent with the charge distribution predicted if an initially pure sample of iron nuclei had traversed some 4 g/cm2 of matter since the initial acceleration. The cosmologically abundant elements sulphur, argon, and calcium appear to be relatively absent from the source, while nickel is only present with the predicted abundance.

The ALICE instrument and the measured cosmic ray elemental abundances

1992 ◽  
Vol 1 (1) ◽  
pp. 33-45 ◽  
Author(s):  
J.A. Esposito ◽  
E.R. Christian ◽  
V.K. Balasubrahmanyan ◽  
L.M. Barbier ◽  
J.F. Ormes ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Elemental Abundances
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