Domenico Pacini ( Marino, February 20, 1878 –

Rome Rome (Italian language, Italian and , ) is the capital city and most populated (municipality) of Italy. It is also the administrative centre of the Lazio Regions of Italy, region and of the Metropolitan City of Rome. A special named with 2, ...

, 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 or astroparticles 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 ...

Biography

He graduated in

Physics Physics is the scientific study of matter, its Elementary particle, 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 whi ...

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, ...

) from 1905 to 1927. Teacher of

Geophysics Geophysics () is a subject of natural science concerned with the physical processes and Physical property, properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct i ...

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 o ...

at the University of Bari 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 this by the movement of a test charge due to the Coulomb's law, Coulomb electrostatic force on it. The amount of charge on ...

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 Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...

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 Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

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 Italian experimental physicists Italian meteorologists 20th-century Italian physicists Academic staff of the Sapienza University of Rome Academic staff of the University of Bari