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 through which to search for these hypothetical particles

Hypothetical particles known as axions may clear up two enigmas directly. They might account for dark matter, the mysterious substance that’s thought to make up a lot of the matter within the universe, they usually may additionally clarify the puzzling symmetry properties of the robust drive that holds protons and neutrons collectively in atomic nuclei.

However the theoretical space of potentialities for axions is huge, each when it comes to their mass and the power 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 for discovery and its outcomes guiding future searches.

In a brand new paper revealed in Nature Communications, a workforce 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 research, the CAST workforce positioned a resonator consisting of 4 cavities inside one of many two bores of the experiment’s magnet with a view to construct an axion detector that appears as a substitute for axions from the Milky Way’s “halo” of dark matter—an axion haloscope, which they named CAST-CAPP.

In a robust magnetic subject, such because the one offered by CAST’s magnet, axions ought to convert into photons. An axion haloscope’s resonator is principally a radio that researchers can tune to seek out the frequency of those axion-converted photons. However the frequency of the axion “radio station” will not be 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 will be tuned to choose up axion alerts starting from 4.774 to five.434 GHz, comparable to axion plenty 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 knowledge locations new bounds on the utmost power of the interplay of axions with photons for axion plenty of 19.74 to 22.47 microelectronvolts, narrowing down the space through 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 knowledge in 2018.

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