Demonstrating the action would mark a key episode in the history of science. This hypothetical particle could solve two fundamental problems in modern physics at the same time: the problem of charge and parity in the strong interaction and the mystery of dark matter. Despite the great scientific interest in finding it, the search at high radio frequency – above 6 GHz – has almost been abandoned due to the lack of the high sensitivity technology that could be built at a reasonable price. Until now.
Instituto de Astrofísica de Canarias (IAC) will participate in an international collaboration to develop DALI (Dark photons & Axion-Like particles interferometer) experiment, an astroparticle telescope for dark matter whose scientific goal is the search for actions and paraphotons in the 6 to 60 GHz band. The prototype, proof of concept, is currently in the design and manufacturing phase at IAC. That white paper describes the experiment has been accepted for publication in Journal of Cosmology and Astroparticle Physics (JCAP).
Predicted by theory in the 1970s, the action is a low-mass hypothetical particle that interacts weakly with standard particles such as nucleons and electrons as well as with photons. These suggested interactions are examined to try to detect the action with different types of instruments. One promising technique is to study the interaction between actions and standard photons.
Axions ‘mix’ with photons under the influence of a strong external magnetic field, such as those produced by the superconducting magnets in particle detectors or those used for medical diagnostics by magnetic resonance, and produce a weak radio or microwave signal. This signal has been searched for in a series of experiments since the late 80s, and it is just the signal that we will now discover with DALI, albeit in a new almost unexplored range of parameters that will be available for the first time thanks to this experiment, ”explains Javier De Miguel, an IAC researcher and the first author of the study.
The first action detectors, manufactured in the 80s and 90s, used a resonant cavity that amplified inside a supermagnet the weak microwave signal predicted from the action and tried to bring it into a power range that could be detected by scientific instruments. Unfortunately, the cavity size is inversely proportional to the scanning frequency, and for the action, the cavities were too small to be made to frequencies greater than approx. 6 GHz.
For this reason, the new experiment brings together the most promising techniques for scanning at high frequencies and includes it in a practical design, to which is also added the capacity of astroparticle detectors for actional dark matter. In this way, DALI includes a powerful superconducting magnet, an action detector with a new resonator that makes the weak signal caused by the actions detectable, and an altazimuth mount that makes it possible to scan objects and regions in the sky looking for dark fabric.
In this way, DALI was able to help detect the action, a pseudo-scalar particle whose nature is similar to that of the Higgs boson, discovered in 2012 at. CERNand a promising candidate for dark matter. Dark matter is a fundamental component of the universe that interacts very weakly with ordinary matter, and it is therefore very difficult to detect directly, but whose discovery will allow us to explain the rotational curves of spiral galaxies and why the formation of structure in the Universe has evolved as hitherto, among other mysteries.
Reference: “A dark matter telescope probing the 6 to 60 GHz band” by Javier De Miguel, April 28, 2021, Journal of Cosmology and Astroparticle Physics.
DOI: 10.1088 / 1475-7516 / 2021/04/75