Cosmic Rays Past and Present

Three speakers came together at ICTP on 8 September 2011 to mark the 100th anniversary of Italian physicist Domenico Pacini's important experiments and observations on cosmic rays. His work helped lay the groundwork for current research in high-energy and particle physics.

Alessandro De Angelis (Università di Udine, INFN Trieste and LIP/IST Lisboa) gave the audience a peek back in time and took them through the steps that finally lead to the understanding that the source of cosmic rays is extraterrestrial.

De Angelis detailed the work of Pacini, who was the first to disagree with the dominant opinion that cosmic rays originated from Earth. De Angelis argued that Pacini's work was overlooked, perhaps due to political and historical reasons as well as  language barriers (Pacini mostly published his work in Italian) and Pacini's own reticent nature. But nevertheless, his work paved the way for Victor Hess's famous balloon experiment, and Hess went on to win the Nobel Prize in Physics in 1936 for the discovery of cosmic radiation.

The second speaker, Francesco Longo (Università di Trieste and INFN Trieste) focused on current advances in cosmic ray detector development and gave the audience an update about the various research teams and the latest experiments in cosmic ray detection.

Claudio Tuniz (ICTP) ended the colloquium by explaining how researchers are looking at cosmic ray detection from a different angle: studying the records of cosmic ray bombardment on different samples, ranging from meteorites to radioisotopes in prehistoric fossil samples.