The first direct search for inelastic boosted dark matter with a terrestrial detector

The first direct search for inelastic boosted dark matter with a terrestrial detector
(a) Production of relativistic BDM χ1 in the Galactic center by the annihilation of heavier dark matter χ0. (b) Illustration of multiple-site hits from an inelastic interaction of BDM for the case of two interactions occurring in two different NaI(Tl) and liquid scintillator (LS) detectors. (c) Illustration of bremsstrahlung radiation-induced hits on two NaI(Tl) or LS detectors. Credit: Ha et al.

A team of researchers in the Republic of Korea, the U.S., Brazil, Indonesia and the U.K. have recently carried out a direct search for inelastic boosted dark matter (IBDM) using a terrestrial detector. Their study, published in Physical Review Letters (PRL), is the first ever to search experimentally for IBDM using a terrestrial detector.

Observations gathered by past astrophysics studies suggest that the universe's dominant matter component is not , but nonbaryonic . Researchers have made tremendous efforts in to search for dark matter via direct detection, indirect detection and collider experiments, yet so far, their attempts have been unsuccessful.

This lack of success encouraged them to search for alternative types of dark matter, such as light-mass models or relativistically boosted dark matter (BDM), which would have substantially different signatures in detectors. Precisely because these new kinds of dark matter would produce unconventional signatures, very few of them have been the focus of traditional dark matter experiments.

"Even though scientists have consistently searched for WIMP (Weakly Interacting Massive Particle) dark matter over the past few decades, no clear signals have yet been observed," Hyun Su Lee, a researcher at the Institute for Basic Science in Daejeon, Korea, who carried out the recent study, told Phys.org. "This has motivated searchers for other types of dark matter, which may give significantly different signals in the . One idea is searching for multi-component dark matter. In this case, each dark matter component is likely WIMP dark matter, but it has a different mass."

The first direct search for inelastic boosted dark matter with a terrestrial detector
Inside the COSINE-100 detector. Credit: Ha et al.

A few years ago, researchers at the University of Maryland and MIT introduced a new model that describes a relativistic dark matter particle boosted by the annihilation of heavier dark matter participles in the galactic center or the sun. According to their model, this would require at least two species of dark matter particles, comprising a multi-component dark matter.

Dark matter candidates with a heavier mass can decay into light dark matter. As mass is equivalent with energy, in the case of multi-component dark matter, mass differences between different components would lead to high speed of light dark matter. The term 'boosted dark matter,' therefore, basically means that incident dark matter has a relatively high velocity.

"The expected signal from high velocity dark matter is energetic electron recoil, while typical dark matter brings low energy nuclear recoil," Lee explained. "This theory has been considerably developed over the past few years. After that, theorists started thinking about , because of the multiple components of dark matter."

The first direct search for inelastic boosted dark matter with a terrestrial detector
The COSINE-100 detector from outside. Credit: Ha et al.

In chemistry and physics, Inelastic scattering is a fundamental process in which the kinetic energy of an incident particle is not conserved, but is either lost or increased. Researchers at CERN, as well as other institutions in Korea and the U.S. have theorized an inelastic interaction of boosted dark matter. According to their theories, relativistic dark matter interacts with the target material through inelastic scattering with electrons, creating a heavier state that later produces standard model particles, such as electron-positron pairs.

"In inelastic scattering, the first energetic electron is produced with an additional dark sector particle," Lee explained. "Such a dark sector particle is decaying into an electron positron pair with some displacement. So far, no experiments have carefully studied these kinds of signals, so we thought that this could be a good alternative scenario to explain the dark matter problem."

In their study, Lee and his colleagues carried out the first direct search for IBDM with a terrestrial detector. Essentially, they immersed eight Nal(TI) crystals with a total mass of 106kg into a 2,200L liquid scintillator surrounded by heavy shields to block radioactive backgrounds.

  • The first direct search for inelastic boosted dark matter with a terrestrial detector
    Inside the COSINE-100 detector. Credit: Ha et al.
  • The first direct search for inelastic boosted dark matter with a terrestrial detector
    Inside the COSINE-100 detector. Credit: Ha et al.
  • The first direct search for inelastic boosted dark matter with a terrestrial detector
    (a) Production of relativistic BDM χ1 in the Galactic center by the annihilation of heavier dark matter χ0. (b) Illustration of multiple-site hits from an inelastic interaction of BDM for the case of two interactions occurring in two different NaI(Tl) and liquid scintillator (LS) detectors. (c) Illustration of bremsstrahlung radiation-induced hits on two NaI(Tl) or LS detectors. Credit: Ha et al.

"We used both NaI(Tl), 106kg, and LS, 2ton, as an active detector to search for one energetic electron plus electron positron pair that deposited energies in two different detector components," Lee said. "Because of the large mass of the detector and its many components, it achieves a relatively good sensitivity for these types of signals."

Unfortunately, Lee and his colleagues were unable to detect IBDM signals in their data. Nonetheless, theirs is a pioneering study, as nobody had previously used detectors to search for this particular type of dark matter.

Their work is part of a greater project, dubbed COSINE-100, which is specifically aimed at testing dark matter annual modulation observed by the DAMA experiment. The researchers think that further searches for IBDM signals using the same detector or other ton-scale dark matter detectors will be more fruitful.

"For the boosted dark search, we will improve our analysis by using about 10 times larger dataset that we already have on disk," Lee said. "We also plan to search elastic scattering channels and expect that an updated search will explore large parameter spaces that have not yet been searched in any other experiments."


Explore further

CERN lab on the hunt for dark matter

More information: C. Ha et al. First Direct Search for Inelastic Boosted Dark Matter with COSINE-100, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.122.131802

(In)direct detection of boosted 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" from Inelastic Boosted Dark Matter. DOI: 10.1103/PhysRevLett.119.161801.
journals.aps.org/prl/abstract/ … ysRevLett.119.161801

An experiment to search for dark-matter interactions using sodium iodide detectors. DOI: 10.1038/s41586-018-0739-1. https://www.nature.com/articles/s41586-018-0739-1

Journal information: Physical Review Letters

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Citation: The first direct search for inelastic boosted dark matter with a terrestrial detector (2019, April 16) retrieved 23 October 2019 from https://phys.org/news/2019-04-inelastic-boosted-dark-terrestrial-detector.html
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Apr 16, 2019
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

Displaced supersolid dark matter is curved spacetime.

In the Bullet Cluster collision the dark matter has not separated from the ordinary matter. The collision is analogous to two boats that collide, the boats slow down and their bow waves continue to propagate. The water has not separated from the boats, the bow waves have. In the Bullet Cluster collision the galaxy's associated dark matter displacement waves have separated from the colliding galaxies, causing the light to lense

Apr 16, 2019
Kudos to Lee & Co for their hunt. Chipping away at the possible 'stuff' Dark Matter isn't...

Of course, if the overlapping shock-fronts of the 'Local Bubble', blown by several supernova, has swept DM from our locale, would there be anything to find ??
Brrr...

Apr 16, 2019
We;ll BW insists, endlessly, that the Universe is filled up with DM as a solid filling.
Isn't this the Theory of Aspic , a cosmos of gelatin?
That what scientists are claiming as Gravity Waves? Are actually the cosmic jello jiggling?

**********

Nik, you overlooked the improbable possibility that the SN Bubbles are just as likely to randomly push DM in our direction, as away from us?

Apr 16, 2019
Bob West blurted: "Dark matter is..."

Stop right there.

Nobody knows what dark matter is. You are exposing your profound ignorance by insisting otherwise.

As an aside, we don't even know if dark matter is matter. A better term would be 'dark gravity' - gravitational effects we can see but can't explain.

Apr 16, 2019
Kudos to Lee & Co for their hunt. Chipping away at the possible 'stuff' Dark Matter isn't...

Of course, if the overlapping shock-fronts of the 'Local Bubble', blown by several supernova, has swept DM from our locale, would there be anything to find ??


Yes, the ACME experiment on Standard Model deviations in electron sphericity has been claimed (by themselves) to eliminate almost all of the remaining simple (one mass, natural) WIMP sector. And axions may not be necessary since the CP breaking could all be in the neutrino sector according to preliminary experiment, not the axion strong force sector. So, kudos indeed.

On the local bubble, good point! The Milky Way DM distribution is "cold", i.e. classical cusped, likely since both star formation and SagA* super massive black hole are relatively calm. But what happens in the local neighborhood, especially for these more interactive dark matter models, I dunno?

Mostly, scientists are still fumbling "in the dark".

Apr 16, 2019
As an aside, we don't even know if dark matter is matter. A better term would be 'dark gravity' - gravitational effects we can see but can't explain.


But here you yourself "insist otherwise". Dark matter is Cold (high mass, low velocity) Dark (weakly/non EM interacting) Matter (particles) in the well tested cosmology. Conversely non-general relativity "effects" are almost entirely excluded [last by the M87* super massive black hole observations; before that by the neutron star binary merger observations].

"Troubled Times for Alternatives to Einstein's Theory of Gravity
New observations of extreme astrophysical systems have "brutally and pitilessly murdered" attempts to replace Einstein's general theory of relativity."

https://www.quant...0180430/

Apr 16, 2019
This article has too many spelling and grammatical errors-- the most I have ever seen on phys.org.

Apr 16, 2019
Recently two papers have been published. The first one deals with the measurement of the speed of rotation of galaxies and, in our view, closes the issue of the existence of dark matter. The second one argues that the expansion of the universe is not accelerating. However, this fact does not answer the question as to what in general is the cause of the universe's expansion and does not address the widespread opinion that 70% of the universe consists of dark energy.
https://www.acade...k_Energy

Apr 16, 2019
The basis for their otherwise baseless approach? "According to their theories, relativistic dark matter interacts with the target material through inelastic scattering with electrons, creating a heavier state that later produces standard model particles, such as electron-positron pairs." The theory of everything no less. Or, in layman's terms, bullshit.


No, a hypothesis. It should be looked at. They did; they found nothing. That doesn't mean it's over, yet. You look, you find nothing; you look again. Sometimes, it takes a while to find something; one look is never enough to rule out an idea. Negative results once mean you look, again.

Regardless, the search continues. We haven't not found dark matter until we've finished looking, and we haven't finished looking. Only when we've looked everywhere several times in several ways do negative results mean a positive "no dark matter."

Then, only, will it be time for other ideas to become most important.

Apr 16, 2019
This article has too many spelling and grammatical errors-- the most I have ever seen on phys.org.
says cowlinator

I was particularly impressed with their use of "participles", so I checked my dictionary and found the word only relates to the use of LANGUAGE (which is a science in and of itself). I was confounded with the thought of participles existing in the Cosmos along with the alleged DM. It was almost as odd as rr's heavy usage of the question mark rather than a comma to link one line of the same sentence to its climactic ending at its end.

"..MIT introduced a new model that describes a relativistic dark matter particle boosted by the annihilation of heavier dark matter participles in the galactic center or the sun. According to their model, this would require at least two species of dark matter particles, comprising a multi-component dark matter."


Apr 16, 2019
So elusive DM remains elusive. That's okay, a process of elimination is what detective work is all about. Scientist coming up with new ideas or a variation on old ones is good for technology etc. May be that we won't get the answer until we can actually get out there and that's going to be a while yet.

Apr 17, 2019
Sometimes, it takes a while to find something

Same thing when people misplace their car keys. They look in the place they think is most likely. Then the next likely one...and so on.
Why they object to scientists using the same approach I have no idea. What do they think scientists are? People who 'magically' know the answer to everything and always only need to look in the 'right' place immediately to find stuff? (That would only work if we had a "theory of everything"...and if we have that we no longer need scientists)

(Of course I have seen people look in the same place twice for their keys. At least that is something scientists don't do. That's why they publish papers of unsuccessful searches so that others don't duplicate fruitless labor)

Apr 17, 2019
An excellent & cogent explanation, a_p.
Real Scientists learn from their failures. & move on to the next experiment.
Forever creating new hypothesize as they invent new ideas.

The woomongering looneyticks remain trapped in their reoccurring failures.
Like hamsters endlessly running on a treadmill.
& never getting anywhere...

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