You are here: Home > More news > Students hunt muons in stratosphere to test theory of relativity


Share Share

The team is seeking financial support through the crowdfunding platform Indiegogo for their project to detect these elementary particles in the atmosphere

Students hunt muons in stratosphere to test theory of relativity

Within the framework of the European REXUS/BEXUS programme, a group of five students from the Universitat Politècnica de Catalunya (UPC) has been selected to design and carry out an experiment in the stratosphere with the aim of testing Einstein’s special theory of relativity. The experiment will involve studying muons, elementary particles present in the atmosphere. The team is the youngest one participating in the programme (and the only one from Spain). Contributions to help fund the project can be made until 8 June at

Second-year UPC students have come together to carry out an interdisciplinary project aimed at verifying the special theory of relativity, a subject they find fascinating. The experiment will involve launching a stratospheric balloon from a base in Sweden in October of this year. The project is being developed within the framework of the REXUS/BEXUS programme, which gives students from around Europe an opportunity to perform experiments on board rockets and stratospheric balloons. The initiative is being pursued under a bilateral agreement between the German Aerospace Centre (DLR) and the Swedish National Space Board (SNSB), in collaboration with the European Space Agency (ESA).

Construction of the particle detector
The project, known as CADMUS (Cloud Chamber for High-Altitude Detection of Muons Under Special Relativity Effects), involves designing and building a particle detector: a cloud chamber for detecting muons, which are elementary particles produced when cosmic rays interact with the Earth’s atmosphere. The main objective is to pick up muon traces and calculate, during the balloon’s ascent, the quantity of these particles detected at each altitude range. These data will be used to obtain the mean lifetime of a muon, which will then be compared to the value predicted by Albert Einstein’s special theory of relativity.

The half-life of a muon is very short—about two microseconds, equivalent to one one-hundredth of a blink of the eye—and according to classical physics they should not survive long enough to reach the Earth’s surface. But the theory of relativity predicts that the particles are moving so fast that they undergo time dilation. This phenomenon is imperceptible unless an object is moving at close to the speed of light. Muons, however, are moving so fast that they are subject to this effect. Verifying the special theory of relativity is important because it directly affects the functioning of satellites and has indirect implications for our mobile phones and other devices.

Scientific experiments intended to observe time dilation have been designed and performed, but up until now the presence of muons has only been measured at two distinct altitudes (at sea level and at a certain elevation on a mountain, for example). In contrast, the CADMUS group’s experiment will study the presence of muons at many altitudes.

A trip to space that poses many challenges
The participating students have thrown themselves into the project, fascinated by the scientific issues involved and excited by the challenge of working in a team on a real, complex engineering project of an interdisciplinary nature that touches on many different fields. They were selected last November after travelling to Amsterdam to present their proposal to a panel of experts and technicians from the German and Swedish space agencies. Along with the other participants in the programme, they have also received training on the requirements their experiments must meet to be launched into space.

The experiment will be performed in October on board a balloon (BEXUS) and a rocket (REXUS), both of which will be launched into the stratosphere. Eight other international experiments will also be along for the trip. The launch will be made from the Swedish agency’s base, which is in Kiruna, a town in the north of Sweden.

Crowdfunding campaign
On 8 June, the CADMUS team launched a crowdfunding campaign through the Indiegogo platform ( to raise the funds needed to carry out the project. They currently have the support of the Cellex Foundation and the UPC’s Interdisciplinary Higher Education Centre (CFIS), Barcelona School of Telecommunications Engineering (ETSETB), and Castelldefels School of Telecommunications and Aerospace Engineering (EETAC). They also receive technical support from experts at the German Aerospace Centre (DLR), the Swedish Space Corporation (SSC), a cooperative project known as EuroLaunch, the Centre of Applied Space Technology and Microgravity (ZARM), and the European Space Agency (ESA).

The CADMUS team is currently working on the design and development of the cloud chamber. The unit will be equipped with two high-speed cameras provided by the Canadian start-up Chronos, which will be used to record images (up to 21,000 frames per second) of fast-moving muon traces during the balloon’s ascent. The cloud chamber, a simple particle detector, contains a supersaturated alcohol vapour atmosphere that makes it possible to observe the trails of charged particles passing through the chamber. It will be made using aluminium, open-cell polyethylene foam (for temperature, humidity and pressure insulation) and rubber bumpers to protect it from vibrations, the outside temperature, and the impact of landing.

Four members of the CADMUS team are in the second year of the bachelor’s degree in Engineering Physics at the Barcelona School of Telecommunications Engineering (ETSETB), and two are simultaneously completing a bachelor’s degree in Mathematics at the School of Mathematics and Statistics (FME). This double degree programme is offered through the Interdisciplinary Higher Education Centre (CFIS). The fifth student in the group is completing a double degree in Aerospace Systems Engineering and Telecommunications Systems Engineering at the Castelldefels School of Telecommunications and Aerospace Engineering (EETAC). The team members are Adam Teixidó, Gerard Pascual, Guillem Megías, Ramon García and Roger Bahí.

Follow us on Twitter Open link in new window
Latest news
From left to right: researchers Eduard Alarcón, Sergi Abadal—holding a tablet in his hands showing the logo of the project and a simulation that is being worked on—and Albert Cabellos Scientists from the UPC investigate reconfigurable and programmable metamaterials Creating materials with programmable electromagnetic properties, called software-defined ... [read +]
MareNostrum 4 MareNostrum 4 begins operation MareNostrum provides 11.1 petaflops of processing power for scientific research [read +]
UPC rises 46 places in QS World University Rankings 2018 The Universitat Politècnica de Catalunya (UPC) has risen 46 positions and once again ranks amongst ... [read +]
In collaboration with:
Fundación Española para la Ciencia y la Tecnología Science Year 2007 Ministerio de Ciencia e Innovación
This website uses cookies to offer you the best experience and service. If you continue browsing, it is understood that you accept our cookies policy Open link in new window.
Oficina de Mitjans de Comunicació.
C/ Jordi Girona 31, 08034 Barcelona Tel.: +34 93 401 61 43
© UPC Open link in new window. Universitat Politècnica de Catalunya · BarcelonaTech