Domenico Pacini ( Marino, February 20, 1878 –

Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus ( legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...

, May 23, 1934) was an Italian

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

noted for his contributions to the discovery of

cosmic rays Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our ...

Biography

He graduated in

Physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

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 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, mo ...

) from 1905 to 1927. Teacher of

Geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...

from 1915 to 1925 at the University of Rome, then professor of

Experimental physics Experimental physics is the category of disciplines and sub-disciplines in the field of physics that are concerned with the observation of physical phenomena and experiments. Methods vary from discipline to discipline, from simple experiments and ...

at the

University of Bari The University of Bari Aldo Moro ( it, Università degli Studi di Bari Aldo Moro) is a state-supported higher education institution founded in 1925 in Bari, Apulia, in Southern Italy. The university is one of the most prestigious universities in ...

from 1928. It had been observed that an

electroscope The electroscope is an early scientific instrument used to detect the presence of electric charge on a body. It detects charge by the movement of a test object due to the Coulomb electrostatic force on it. The amount of charge on an object is ...

in a vessel at earth potential gradually lost its charge, even if very carefully insulated, due to the

ionization Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecul ...

of the air. Pacini observed simultaneous variations of the rate of

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

References

External links

University of Pavia, Biography of Domenico Pacini
* A. De Angelis et al., "Domenico Pacini, un pioniere dimenticato dello studio dei raggi cosmici", Nuovo Saggiatore 24 (2008) 70

{{DEFAULTSORT:Pacini, Domenico 1878 births 1934 deaths People from Marino, Lazio Experimental physicists Italian meteorologists 20th-century Italian physicists Sapienza University of Rome faculty University of Bari faculty