Domenico Pacini
Encyclopedia
Domenico Pacini was an Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

 noted for his contributions to the discovery of cosmic rays.

Biography

He graduated in Physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 at the University of Rome in 1902. Assistant at the "Regio Ufficio Centrale di Meteorologia e di Geodinamica" (Italian Agency of Meteorology and Geodynamics
Geodynamics
Geodynamics is a subfield of geophysics dealing with dynamics of the Earth. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mountain building, volcanoes, earthquakes, faulting and...

) from 1905 to 1927. Teacher of Geophysics
Geophysics
Geophysics is the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and...

 from 1915 to 1925 at the University of Rome, then professor of Experimental physics
Experimental physics
Within the field of physics, experimental physics is the category of disciplines and sub-disciplines concerned with the observation of physical phenomena in order to gather data about the universe...

 at the University of Bari
University of Bari
The University of Bari is a university located in Bari, Italy. It was founded in 1925 and is organized in 12 Faculties.-Organization:These are the 13 faculties in which the university is divided into:* Faculty of Agricultural Science...

 from 1928.

It had been observed that an electroscope
Electroscope
An electroscope is an early scientific instrument that is used to detect the presence and magnitude of electric charge on a body. It was the first electrical measuring instrument. The first electroscope, a pivoted needle called the versorium, was invented by British physician William Gilbert...

 in a vessel at earth potential gradually lost its charge, even if very carefully insulated, due to the ionization
Ionization
Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation. A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar...

 of the air. Pacini observed simultaneous variations of the rate of ionization
Ionization
Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation. A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar...

 on mountains, over a lake, over the sea, and underwater. In an experiment performed in June 1911, Pacini concluded that ionization underwater was significantly lower than on the sea surface. He could then demonstrate that a certain part of the ionization itself must be due to sources other than the radioactivity of the Earth, thus contributing to the discovery of cosmic rays.

External links

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