A team of researchers in the Republic of Korea, the USA. UU., Brazil, Indonesia and the USA. UU They have recently conducted a direct search for enhanced inelastic dark matter (IBDM) using a ground detector. His study, published in Physical revision letters (PRL), is the first to experimentally search for IBDM using a terrestrial detector.
The observations collected by the astrophysical studies of the past suggest that the dominant matter component of the universe is not ordinary matter, but dark non-baronial matter. Researchers have made enormous efforts in the search for dark matter through direct detection, indirect detection and colliding experiments, but so far, their attempts have not been successful.
This lack of success encouraged them to look for alternative types of dark matter, such as luminous mbad models or dark matter with relativistic harlots (BDM), which would have substantially different signatures on the detectors. Precisely because these new types of dark matter would produce unconventional signatures, very few of them have been the focus of traditional dark matter experiments.
"Although scientists have systematically searched for the dark matter WIMP (Mbad Particle that Weakly Interacts) in recent decades, clear signals have not yet been observed," said Hyun Su Lee, a researcher at the Institute of Basic Sciences in Daejeon, Korea. He carried out the recent study, said Phys.org. "This has motivated searchers of other types of dark matter, which can give significantly different signals in the detector.One idea is the search for dark matter of multiple components.In this case, each component of dark matter is probably dark matter WIMP , but it has a different mbad. "
A few years ago, researchers at the University of Maryland and MIT introduced a new model that describes a particle of relativistic dark matter driven by the annihilation of the heavier dark participles of matter at the galactic center or the sun. According to its model, this would require at least two species of dark matter particles, comprising a dark matter of multiple components.
Candidates of dark matter with a heavier mbad can decompose into light dark matter. Since mbad is equivalent to energy, in the case of multi-component dark matter, differences in mbad between the different components would lead to a high velocity of light dark matter. The term & # 39; boosted dark matter & quot ;, therefore, basically means that incident dark matter has a relatively high velocity.
"The expected signal from high-speed dark matter is the energetic recoil of the electrons, while the typical dark matter produces a low-energy nuclear recoil," Lee explained. "This theory has developed considerably in recent years." After that, theorists began to think about inelastic scattering, due to the multiple components of dark matter.
In chemistry and physics, inelastic scattering is a fundamental process in which the kinetic energy of an incident particle is not conserved, but is lost or increased. CERN researchers, as well as other institutions in Korea and the United States, have theorized an inelastic interaction of enhanced dark matter. According to his theories, relativistic dark matter interacts with the target material through inelastic scattering with electrons, creating a heavier state that then produces standard model particles, such as pairs of electrons and positrons.
"In inelastic scattering, the first energetic electron is produced with an additional dark sector particle," Lee explained. "Such a dark particle of the sector is disintegrating into a pair of positrons of electrons with some displacement." So far, no experiment has carefully studied this type of signals, so we thought that this could be a good alternative scenario to explain the problem of dark matter. "
In their study, Lee and his colleagues conducted the first direct search for IBDM with a ground detector. Essentially, they submerged eight crystals of Nal (TI) with a total mbad of 106 kg in a liquid scintillator of 2,200 liters surrounded by thick shields to block the radioactive funds.
"We use both NaI (Tl), 106kg, and LS, 2ton, as an active detector to look for a pair of electron positrons plus energetic electrons that deposit energies in two different components of the detector," Lee said. "Due to the great mbad of the detector and its numerous components, it achieves a relatively good sensitivity for this type of signals".
Unfortunately, Lee and his colleagues could not detect the IBDM signals in their data. However, yours is a pioneering study, since no one had previously used detectors to search for this particular type of dark matter.
His work is part of a larger project, called COSINE-100, which is specifically aimed at testing the annual modulation of dark matter observed by the DAMA experiment. The researchers believe that a greater search for IBDM signals with the same detector or other detectors of dark matter at ton scale will be more fruitful.
"For the search for increased dark matter, we will improve our badysis using a 10 times larger data set than we already have on the disk," Lee said. "We also plan to look for elastic dispersion channels and hope that an updated search will explore large parameter spaces that have not yet been searched in any other experiment."
CERN laboratory hunting dark matter.
C. Ha et al. First direct search for increased inelastic dark matter with COSINE-100, Physical revision letters (2019). DOI: 10.1103 / PhysRevLett.122.131802
(In) Direct detection of enhanced dark matter. DOI: 10.1088 / 1475-7516 / 2014/10/062. https://iopscience.iop.org/article/10.1088/1475-7516/2014/10/062/meta
Dark matter "Collider" of Inelástica enhanced dark matter. DOI: 10.1103 / PhysRevLett.119.161801.
An experiment to look for dark matter interactions using sodium iodide detectors. DOI: 10.1038 / s41586-018-0739-1. https://www.nature.com/articles/s41586-018-0739-1
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The first direct search for inelastic dark matter enhanced with a ground detector (2019, April 16)
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