This image reproduces the operation of the cosmic ray detector designed and built for the temporary exhibition: “In/visibility. Arturo Duperier y los rayos cósmicos”, which is on display at the Spanish National Science and Technology Museum in Alcobendas (Madrid), showing the real events it records.

Each circle represents a Geiger tube of the detector, these tubes are triggered when a charged particle passes through them, and the corresponding circle lights up. When one Geiger in the top row and one in the bottom row are triggered almost simultaneously, we interpret this as a cosmic ray particle passing through, and record in real time the time and direction of its arrival.