Narrowing the theoretical space in which to look for dark matter

The CAPP axion haloscope on the CAST experiment has hunted for axions from the Milky Way’s “halo” of dark matter, and has narrowed down the theoretical space during which to search for these hypothetical particles

Hypothetical particles referred to as axions might remedy two enigmas without delay. They may account for dark matter, the mysterious substance that’s thought to make up a lot of the matter within the universe, they usually might additionally clarify the puzzling symmetry properties of the robust power that holds protons and neutrons collectively in atomic nuclei.

However the theoretical space of potentialities for axions is huge, each by way of their mass and the energy of their interplay with different particles. Axion searches are subsequently concentrating on completely different areas of this space, every search bringing with it the potential of discovery and its outcomes guiding future searches.

In a brand new paper printed in Nature Communications, a crew of researchers engaged on the CAST experiment at CERN report how they’ve repurposed a part of the experiment to focus on a beforehand uncharted area of the axion space.

CAST was initially designed to hunt for axions originating from the sun. Of their new examine, the CAST crew positioned a resonator consisting of 4 cavities inside one of many two bores of the experiment’s magnet with a purpose to construct an axion detector that appears as an alternative for axions from the Milky Way’s “halo” of dark matter—an axion haloscope, which they named CAST-CAPP.

In a powerful magnetic area, such because the one supplied by CAST’s magnet, axions ought to convert into photons. An axion haloscope’s resonator is mainly a radio that researchers can tune to seek out the frequency of those axion-converted photons. However the frequency of the axion “radio station” is just not recognized, so the researchers should slowly scan a band of frequencies to attempt to establish the frequency of the axion sign.

The CAST-CAPP resonator could be tuned to select up axion alerts starting from 4.774 to five.434 GHz, similar to axion lots of between 19.74 and 22.47 microelectronvolts.

The CAST researchers scanned this 660 MHz band of frequencies in steps of 200 kHz for 4124 hours, from 12 September 2019 to 21 June 2021, and remoted recognized background alerts such because the 5 GHz Wi-fi Native Space Community (WLAN), however didn’t choose up any sign coming from axions. Nonetheless, the CAST-CAPP information locations new bounds on the utmost energy of the interplay of axions with photons for axion lots of 19.74 to 22.47 microelectronvolts, narrowing down the space during which to search for axion dark matter.

The brand new bounds are complementary to outcomes from earlier axion searches, together with these from one other CAST haloscope, RADES, which took information in 2018.

The hunt for dark matter continues. Tune in to this station once more to test for updates from CAST-CAPP or from different dark-matter investigations going down at CERN, comparable to searches for dark matter which may be produced on the Giant Hadron Collider.