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Rossi, Bruno Benedetti

rays particles cosmic ray

(1905–94) Italian–US physicist: discovered cosmic rays to be positively charged particles and found first astronomical X-ray source.

In 1934 Rossi demonstrated that many cosmic rays are positively charged particles by an experiment in the Eritrean mountains, using two sets of Geiger counters pointing east and west. A 26% excess of particles travelling in an eastward direction was found, indicating that these cosmic rays were positively charged particles and were deflected eastwards by the Earth’s magnetic field. In fact, later work has shown that cosmic rays consist mainly of protons and a small proportion of heavy positive nuclei, together with electrons, all of high energy and coming from the Sun, probably with a contribution from supernovae.

Rossi also contributed to the birth of X-ray astronomy in 1962: he led a team which discovered the isotropic flux of X-rays incident on the Earth, and the first astronomical discrete X-ray source, Scorpio X-1, by use of a rocket-borne probe.

Roudanez, Louis C.(1823–1890) - Editor, physician, Begins Medical Career and L’Union Newspaper, Chronology, Launches New Orleans Tribune [next] [back] Rossby, Carl-Gustaf (Arvid)

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