Portal:Radiation astronomy/Resource/13
Electrons edit
Although electron astronomy is usually not recognized as a formal branch of astronomy, the measurement of electron fluxes help to understand a variety of natural phenomena.
Particles such as electrons are used as tracers of cosmic magnetic fields.[2] "From a plasma-physics point of view, the particles represent the correct way to identify magnetic field lines."[2] "The suprathermal electrons in the solar wind and in solar particle events have excellent properties for this application: they move rapidly, they remain tightly bound to their field lines, and they may arrive "scatter-free" even at low energies, and from deep in the solar atmosphere (Lin 1985)."[2] These electrons "provide remote-sensing observations of distant targets in the heliosphere - the Sun, the Moon, Jupiter, and various heliospheric structures."[2] ""[E]lectron astronomy" has an interesting future".[2]
A delta ray is characterized by very fast electrons produced in quantity by alpha particles or other fast energetic charged particles knocking orbiting electrons out of atoms. Collectively, these electrons are defined as delta radiation when they have sufficient energy to ionize further atoms through subsequent interactions on their own.
"The conventional procedure of delta-ray counting to measure charge (Powell, Fowler, and Perkins 1959), which was limited to resolution σz = 1-2 because of uncertainties of the criterion of delta-ray ranges, has been significantly improved by the application of delta-ray range distribution measurements for 16O and 32S data of 200 GeV per nucleon (Takahashi 1988; Parnell et al. 1989)."[3] Here, the delta-ray tracks in emulsion chambers have been used for "[d]irect measurements of cosmic-ray nuclei above 1 TeV/nucleon ... in a series of balloon-borne experiments".[3]
References edit
- ↑ S. Wolpert (July 24, 2008). Scientists solve 30-year-old aurora borealis mystery. University of California. http://www.universityofcalifornia.edu/news/article/18277. Retrieved 2008-10-11.
- ↑ 2.0 2.1 2.2 2.3 2.4 H. S. Hudson and A. B. Galvin (September 1997). A. Wilson. ed. Correlated Studies at Activity Maximum: the Sun and the Solar Wind, In: Correlated Phenomena at the Sun, in the Heliosphere and in Geospace. Noordwijk, The Netherlands: European Space Agency. pp. 275-82. ISBN 92-9092-660-0. Bibcode: 1997ESASP.415..275H.
- ↑ 3.0 3.1 T. H. Burnett et al.; The JACEE Collaboration (January 1990). "Energy spectra of cosmic rays above 1 TeV per nucleon". The Astrophysical Journal 349 (1): L25-8. doi:10.1086/185642. http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990ApJ...349L..25B&link_type=GIF&db_key=AST. Retrieved 2011-11-25.