The IFT contributes to the international MIGDAL experiment, opening a new path in the search for dark matter

• The dark matter group at IFT has developed one of the optical detectors for the MIGDAL experiment, a crucial component for correctly interpreting the results of direct searches of this invisible side of the universe.
• Thanks to the Migdal effect, it may be possible to detect dark matter particles with much lower masses than the current threshold, opening a unique window below the GeV scale.
  

The dark matter group at the Institute for Theoretical Physics (IFT UAM-CSIC) has contributed to the development of instrumentation for the MIGDAL experiment, an ambitious international initiative aimed at confirming a new method to search for dark matter signals through a phenomenon that has yet to be observed experimentally: the Migdal effect. 

“The Migdal effect is a prediction from atomic physics, but so far, no one has been able to observe it,” explains Elías López Asamar, a member of the dark matter group at IFT. “What we want to do is ensure that it exists and that it matches the theoretical predictions. Several experiments are trying to observe it for the first time, and our experiment—appropriately named MIGDAL—is one of them.”

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Part of the electronics that will be used in the MIGDAL dark matter detection experiment has been built at the High Energy Laboratory of the UAM. /IFT.

What is the Migdal effect?

When a neutral particle, such as a neutron or a hypothetical dark matter particle, passes through an atom, it can interact with the nucleus and cause it to recoil. In the process, the atomic electrons may momentarily "lag behind" and be ejected, producing an indirect ionization of the atom. This signal may be easier to detect than the pure nuclear recoil, allowing for the observation of signals that would otherwise be below the energy threshold of current detectors.

“The Migdal effect offers a unique window for searching for dark matter below the GeV scale,” says López Asamar. “With this effect, we can lower the typical detection threshold from around 5 GeV to below 500 MeV, or even less.”

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Elías López Asamar, at the High Energy Laboratory of the UAM /Luis Barta.

IFT’s Contribution: Developing High-Sensitivity Detectors

The MIGDAL experiment, located at the ISIS Neutron and Muon Source in the UK, is an international collaboration that includes institutions from several countries, among them IFT and the Autonomous University of Madrid (UAM).

The MIGDAL experiment consists of a gas volume approximately 30 cm long, where the tracks of very low-energy particles are observed with high resolution. With two data-taking runs already completed and a third scheduled for 2025, the experiment has recently been upgraded with new instrumentation and more sensitive detectors—including the system developed by IFT. López Asamar explains this in a video recorded from the laboratory.

Once assembled, the instrument will be shipped to the UK and integrated into the experiment.