Explorations in dark matter are advancing with new experimental techniques designed to detect axions, leveraging advanced technology and interdisciplinary collaboration to uncover the secrets of this elusive component of the cosmos.
Dark matter, a mysterious and invisible substance, comprises approximately 85% of all matter in the universe. Despite its prevalence, scientists have struggled to understand its composition. Numerous experiments have been conducted to unveil the nature of dark matter, but they have fallen short.
Yale University in the US is now offering a new tactic to explore dark matter. This new experiment, currently under construction, aims to shed light on the enigma of dark matter.
Dark matter has existed in the universe since its inception, playing a significant role in bringing stars and galaxies together. Although invisible and subtle, dark matter does not seem to interact with light or other forms of matter. This suggests that it must be something entirely new.
The standard model of particle physics, which describes fundamental particles, is incomplete. Physicists have been searching for new fundamental particles, and the flaws in the standard model have provided valuable hints about where these particles might be hiding.
One such example is the neutron, which is made up of three charged constituent particles called quarks. Although the neutron is overall neutral, physicists had expected it to have an electric dipole moment, meaning that certain parts of it would be positively charged and others negatively charged. However, attempts to measure this dipole moment have consistently shown that it is too small to be detected. This discrepancy between theory and measurement led physicists to propose a solution.
Roberto Peccei and Helen Quinn, along with later contributions from Frank Wilczek and Steven Weinberg, suggested that the parameter describing the dipole moment is not zero, but rather a dynamical quantity that evolved to zero over time. This hypothetical evolution would have left behind a multitude of light, sneaky particles known as axions.
Axions are now considered one of the leading candidates for dark matter. They would interact weakly with other particles, but they could still transform into ordinary particles, including photons (particles of light), in certain circumstances, such as in the presence of a magnetic field. This characteristic makes axions an ideal candidate for experimental physicists to study.
Several experiments are currently being conducted in controlled lab environments to detect the presence of axions. One approach involves converting light into axions and then back into light on the other side of a wall. Another highly sensitive approach targets the halo of dark matter permeating the galaxy, using a device called a haloscope.
Unfortunately, searching for axions is akin to looking for a needle in a haystack. The frequencies at which axions may be detected cannot be predicted in advance, so scientists must scan all potential frequencies. To address this challenge, new experiments are being designed based on metamaterials, engineered materials with unique properties.
The Axion Longitudinal Plasma Haloscope (Alpha) experiment, currently being developed, utilizes a cavity filled with conductive rods made of metamaterials. This cavity provides a characteristic frequency as if it were one million times smaller, allowing for more focused detection.
While the technology is still under development and will take a few years before it begins producing meaningful data, the progress being made in detecting axions holds great promise. This progress is the result of collaboration among various fields of science, including solid-state physicists, electrical engineers, particle physicists, and mathematicians.
The implications of these advancements in understanding dark matter are vast. Dark matter has