Schematic of the global GNOME (Global Network of Optical Magnetometers for Exotic Physics Searches) network. (Image: Hector Masia Roig)
An international team of researchers from the PRISMA+Cluster of Excellence project, a collaboration between Johannes Gutenberg University (JGU) and the Helmholtz Institute (HIM) in Mainz, has published for the first time integrated data on the use of a global network of optical magnetometers to find dark matter. According to the analysis of scientists, the dark matter field produces a signal with some characteristic characteristic, which can be detected by different sites in the GNOME network through relevant detection. The researchers analyzed data from GNOME running continuously for a month and still did not get the corresponding results. But in their report, published in the journal Nature Physics, they point out that the measurements can lead to restrictions on the properties of dark matter.
GNOME was built by multinational cooperation, magnetometers are distributed in Germany, Serbia, Poland, Israel, South Korea, China, Australia and the United States and other countries in the world. The researchers are keen to use the GNOME project to advance the search for dark matter, the most exciting challenge in 21st century fundamental physics. After all, it has long been known that dark matter can explain many confusing astronomical observations, such as the rotation rate of stars in galaxies or the spectra of the cosmic background radiation.
(Image source: Paul Volkmer/Unsplash)
Ultralight boson particles are considered one of the most promising candidates for dark matter today. These include axion-like subparticles, or ALP for short. Professor Dmitry Budker, who is part of PRISMA+ and HIM (HIM is a joint institute of johannes Gutenberg University in Mainz and the GSI Helmhol Subparticle Institute in Darmstadt), believes that these axial subclass particles can also be seen as classical fields oscillating at a certain frequency. Depending on possible theoretical scenarios, a feature of this bosonic subfield is that certain patterns and structures of matter can be formed. Thus, the density of dark matter can be concentrated in many different regions, such as discretely distributed into "(particle) walls" that are smaller than galaxies but far larger than Earth.
If this axion-like "wall" arrives on Earth and generates an instantaneous signature signal in the magnetometer, the GNOME network can gradually detect the signal. Dr. Arne Wickenbrock, one of the study's participants, believes that these signals are correlated in some way, depending on how fast the "wall" moves and when it reaches each probe point.
The network consists of 14 magnetometers in 8 countries around the world. Nine of these strong magnetometers have provided data for the current study. The measurement principle is based on the interaction between dark matter and the nuclear spin of the original son in the magnetometer. When an atom is excited by a laser of a particular frequency, the spin of its nucleus is oriented in a certain direction. The potential dark matter field can interfere with this direction, so that the signal generated by the dark matter particles can be measured.
Dr. Hector Masia-Roig of Budker's group made a figurative analogy: One could imagine atoms originally in a magnetometer as dancing in chaos, spinning together when they "captured" a laser of the right frequency. Dark matter particles can throw dancing atoms out of balance. This disturbance can be measured precisely. Magnetometer networks play a very important role in this: when a certain range of dark matter walls pass through the earth, the "dancing" atoms in all the detection points on the earth are gradually disturbed. For example, one of the sites in the network is located in a laboratory at the Helmholtz Institute in Mainz. Hector Masia-Roig notes: "It is only when we have matched the signals of all sites that we can assess what triggered the interference. For an image made up of dancing "atoms," comparing the measurements of all the sites, we can tell whether this is the provocation of a "brave dancer" or the interference of a dark matter "wall."
Magnetometers measure planetary magnetic fields. (Image source: Wikipedia)
In this phase of the study, the team analyzed data from GNOME's one-month run. It was found that no statistically significant signals appeared in the survey range from one flying electron volt (feV) to 100,000feV. Instead, compared to previous results, researchers can narrow down the theoretical scope of the signal found. Even if, as another PhD student, Joseph Smiga, puts it, "although we cannot yet use a global ring search to detect such a regional dark matter 'wall'", this is an important result for a scheme to detect discrete dark matter 'walls'.
In the future, GNOME's collaborative work will focus on improving magnetometer performance and data analysis, in particular making its operation more continuous and stable. This is essential for continuous and reliable search for signals that take longer than an hour. In addition, the alkali atoms in magnetometers will be replaced with inert gas atoms. The researchers expect this to greatly increase the sensitivity of future measurements in searching for dark matter.
Translator: Fan Jiahao
Reviewer: Dong Zi Chenxi
Source of introduction: Universityaet Mainz
This article is from: China Digital Science and Technology Museum