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
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 ...
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
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 ...
.
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