Atmospheric ionization and cosmic rays: studies and measurements before 1912

Abstract

The discovery of cosmic rays, a milestone in science, was based on the work by scientists in Europe and the New World and took place during a period characterised by nationalism and lack of communication. Many scientists that took part in this research a century ago were intrigued by the penetrating radiation and tried to understand the origin of it. Several important contributions to the discovery of the origin of cosmic rays have been forgotten; historical, political and personal facts might have contributed to their substantial disappearance from the history of science.

How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

“…The former results from the electrode effect of the negatively charged Earth surface, which repels negative ions in its vicinity, and it is a well-known phenomenon in the atmospheric electricity community (Harrison and Carslaw, 2003;Israël, 1970;Tinsley, 2008;Wilson, 1921). The latter agrees with observations that generally negative ions possess higher mean mobility than positive ions (Dhanorkar and Kamra, 1992;Hõrrak, 2001;Israël, 1970); i.e. on average, negative ions are of smaller sizes than positive ions.…”

“…Why the air was conductive could not, however, be explained. Meanwhile, Charles-Augustin de Coulomb observed gradual discharge of a well-insulated electroscope around 1785 and he attributed his observation to the contact of suspending particles present in the air (De Angelis, 2014;Walter, 2012). This phenomenon was reproduced by Michael Faraday half a century later in 1835 (De Angelis, 2014).…”

“…Meanwhile, Charles-Augustin de Coulomb observed gradual discharge of a well-insulated electroscope around 1785 and he attributed his observation to the contact of suspending particles present in the air (De Angelis, 2014;Walter, 2012). This phenomenon was reproduced by Michael Faraday half a century later in 1835 (De Angelis, 2014). Thanks to the further improvement of the electroscope by William Thomson and Lord Kelvin (De Angelis, 2014;Flagan, 1998), Crookes (1878) found that the discharge rate of an electroscope decreases with a decreasing air pressure, suggesting that it is the air inside the instrument that manipulates the discharge.…”

“…Thanks to the further improvement of the electroscope by William Thomson and Lord Kelvin (De Angelis, 2014;Flagan, 1998), Crookes (1878) found that the discharge rate of an electroscope decreases with a decreasing air pressure, suggesting that it is the air inside the instrument that manipulates the discharge. However, the reasoning remained undisclosed until the discovery of radioactivity by Wilhelm Röntgen, Henri Becquerel and Marie and Pierre Curie enabled Julius Elster and Hans Geitel from Germany and Charles Thomson Rees Wilson from Scotland to relate the spontaneous discharge of the electroscope to ionisation of the air by radioactive sources (Carlson and De Angelis, 2011;De Angelis, 2014;Wilson, 1895Wilson, , 1899. Therefrom, the importance of air ions in the atmosphere emerged.…”

Millicharged particles from the heavens: single- and multiple-scattering signatures

“…Since the earliest times, humans have stared at the sky and wondered. By observing the low-orbit Earth skies, they discovered the presence of extraterrestrial charged particles, now called cosmic rays [1][2][3][4]. These experimental efforts started from attempts to understand the origin of environmental radioactivity, and through their study led to the discovery of muons in 1936 [5] and pions in 1947 [6].…”