XENON1T experimental data establishes most stringent limit on dark matter

May 30, 2018 by Mary L. Martialay, Rensselaer Polytechnic Institute
Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1X10-47 square centimeters--one-trillionth of one-trillionth of a centimeter squared--the most stringent limit yet determined for dark matter as established by the world's most sensitive detector. Credit: XENON Collaboration

Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1X10-47 square centimeters—one-trillionth of one-trillionth of a centimeter squared—the most stringent limit yet determined for dark matter as established by the world's most sensitive detector.

The results, presented Monday in a seminar in Italy at the Gran Sasso Underground Laboratory (LNGS), were produced using an active target volume of 1,300 kilograms of Xenon, the first search for that has monitored the equivalent of one ton of for an entire year.

"We now have the tightest limit for what is known as 'the WIMP-nucleon cross section,' which is a measure of the effective size of dark matter, or how strongly it interacts with normal matter," said Ethan Brown, a member of the XENON Collaboration, and assistant professor of physics, applied physics, and astronomy at Rensselaer Polytechnic Institute. "With these results, we have now tested many new theoretical models of dark matter and placed the strongest constraints on these models to date."

Dark matter is theorized as one of the basic constituents of the universe, five times more abundant than . But because the dark matter particles known as "weakly interacting massive particles," or "WIMPs," cannot be seen and seldom interact with ordinary matter, their existence has never been confirmed.

Several astronomical measurements have corroborated the existence of dark matter, leading to a worldwide effort to directly observe dark matter particle interactions with ordinary matter. Up to the present, the interactions have proven so feeble that they have escaped direct detection, forcing scientists to build ever-more-sensitive detectors.

Since 2002, the XENON Collaboration, incorporating 165 scientists from 12 countries, has operated three successively more sensitive liquid xenon detectors in LNGS in Italy, and XENON1T is its most powerful venture to date and the largest of its type ever built. Particle interactions in create tiny flashes of light, and the detector is intended to capture the flash from the rare occasion in which a collides with a xenon nucleus.

The results analyze 279 days of data, according to Elena Aprile, a professor at Columbia University and project lead. During that time, only two background events were expected in the innermost, cleanest region of the detector. However, no events were detected, suggesting dark matter particles must be even smaller than previously thought. A portion of the data analysis was conducted at Rensselaer, as scientists from collaborating institutes around the world convened at the Institute late in 2018 to review data and finalize analysis routines that would eliminate irrelevant information from the collected data.

The sensitivity of the detector is a function of its size and its "silence." Although dark matter interactions are rare, interactions with other forms of are common, and a sensitive detector is designed to minimize those interactions. To shield it from natural radioactivity in the cavern, the detector (a so-called Liquid Xenon Time Projection Chamber) sits within a cryostat submersed in a tank of water. A mountain above the underground laboratory further shields the detector from cosmic rays.

Even with shielding from the outside world, contaminants seep into the xenon from the materials used in the detector itself and, among his contributions, Brown is responsible for a sophisticated purification system that continually scrubs the xenon in the detector. As the size of detectors have grown, so has the complexity of the purification system—not only is there more xenon to clean, but it must be kept cleaner so that light and charge may move through the greater volume of the detector. In the current phase, Brown said his team "scaled up, adding more pumps and more purifiers" to the system.

"Our work has maintained a high level of purity for the largest quantity of xenon over the longest period of time ever," said Brown. "It's an accomplishment that allows other experiments to build on the performance of this purification system."

In the next phase, Brown will introduce a new solution, a newly designed pump built with ultra clean parts in his laboratory at Rensselaer in collaboration with researchers at Stanford and at Muenster University in Germany. Where the current pumps contribute one-third to one-half of the total radon in the experiment, the new pumps will be essentially radon-free, removing one of the largest contributions to background.

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NoStrings
1 / 5 (2) May 30, 2018
Dark matter gives physicist so much to do. Is it light or heavy? Does it interact with matter or itself, or not? Does it exist in all galaxies, and if so, in what distribution. If it does exist in such a distribution, how it happen to form as we imagine it to form? And no one have seen it or measured it, but how many hypotheses it can fuel. Endless. And we crackpots can fantasize too, to our delight.

Honestly, if dark matter didn't exist, physicists would have to invent it.
antialias_physorg
4.4 / 5 (7) May 30, 2018
Honestly, if dark matter didn't exist, physicists would have to invent it.

Not really. There's plenty of other stuff that keeps physicists up at night.

Dark matter research is still in a very early state. When we look back at e.g. the history of electromagnetism research, gravity research or the structure of the atom we see similar patterns: At first there is a slew of theories which get whittled down over time as one by one they get disproven. And this takes time (in the case of the atom more than a millenium).

I find it somewhat bizarre that people expect that we jump from "Hey, there's an effect here and we call it dark matter" to a fully proven/demonstrated theory of what it actually is within a matter of a few years/decades.
Laymen are watching entirely too many Hollywood movies and think that's how science goes: Theory (which is immediately correct) and then - bam - household gadget based on it 10 minutes later.
firastaji
1 / 5 (7) May 30, 2018
dark mater is nothing but a Hydrino, a smaller virgin of hydrogen atom, where its electron is in lower level than classical ground state. it does not absorb light nor emit it.
ta2025
1 / 5 (3) May 30, 2018
They will never find Dark Matter / Energy that way. It is not a physical particle that is "detectable" It emerges from a higher dimension and matter is derived from it. It is what space/time is constructed of and it is the material that causing the expansion of the universe. The between dark matter particles is repulsive in the same way that the force between standard matter is attractive.
jonesdave
5 / 5 (7) May 30, 2018
dark mater is nothing but a Hydrino, a smaller virgin of hydrogen atom, where its electron is in lower level than classical ground state. it does not absorb light nor emit it.


There is no such thing as a 'hydrino'. It is an invention of a con artist named Randell Mills, who uses it to con money from people with the promise of cheap energy. No serious scientist takes him seriously. He's been promising delivery of this energy for over two decades. It never arrives. It never will.
ta2025
5 / 5 (1) May 30, 2018
Another Dark matter study posted today: https://www.space...-of.html
aeolius
not rated yet May 30, 2018
It would have been nice to tell the uninformed exactly which type of known particles are under 4.1X10-47 square centimeters.
jonesdave
not rated yet May 30, 2018
It would have been nice to tell the uninformed exactly which type of known particles are under 4.1X10-47 square centimeters.


Errr, that would be difficult. If they were known particles that would imply that we had already detected them. That would have made the front pages.
fthompson495
1 / 5 (2) May 30, 2018
The notion of WIMPs is incorrect. Dark matter is a supersolid that fills 'empty' space and is displaced by visible matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the dark matter. The state of displacement of the dark matter is gravity.
ForFreeMinds
not rated yet May 30, 2018
That no theoretically detectable events have occurred, suggests to me they may be on a wild goose chase. But I look forward to new results and theories being tested.
rrwillsj
2.3 / 5 (3) May 30, 2018
jd, I have a neighbor who fell for that hydrogen power scam. He added the junk 'reactor' to his engine, that the swindlers sold him. Never got it working.

For years, he kept fiddling with the devices. Kept buying more junk from the bunco artists.

They sell or trade among themselves, their lists of gullible. So when the first effort fails, a new scammer would show up to sell you the 'latest discovery!'. "It'll work this time, we promise."

That old truck is still sitting in his driveway. Decaying into rust as the engine is trashed.

I guess it's a good thing that he'd never produced any hydrogen fuel? I'm sure it could have been a spectacular fire!

"Oh the Humanity!"

And to paraphrase Thomas Edison. "He invented thousands of ways NOT to make a commercially usefull lightbulb."
ZoeBell
May 30, 2018
This comment has been removed by a moderator.
ZoeBell
May 30, 2018
This comment has been removed by a moderator.
kurtstocklmeir
1 / 5 (4) May 31, 2018
for years I have talked about this - there is not any dark matter - the spring constant of time and space are not linear and this influences forces created by shape of time and space Kurt Stocklmeir
DonGateley
not rated yet May 31, 2018
I have to wonder how they could make any statement about size given that nothing was detected at all. If there are dark matter particles and their interactions are simply too weak to detect in the laboratory they could be any size whatsoever.
ZoeBell
Jun 02, 2018
This comment has been removed by a moderator.
cantdrive85
1.8 / 5 (5) Jun 02, 2018
Dark matter is dead, the darkists just don't want to admit it.
TheGhostofOtto1923
3 / 5 (4) Jun 02, 2018
Hey willis
jd I have a neighboor
-and from your performance here to date its clear that youre the kind of person who would make up a story like this in its entirety. More suspect because it appears to demonstrate your superior judgement. While making up stories demonstrates your pathological judgement.

A dichotomy.
ZoeBell
Jun 02, 2018
This comment has been removed by a moderator.
jonesdave
5 / 5 (1) Jun 02, 2018
https://www.nbcnews.com/mach/science/why-some-scientists-say-physics-has-gone-rails-ncna879346 The XENON WIMPs searches are typical example of wasteful extensive science in decadent EU style.


As opposed to talking endless crap on a sci-news comments section. Yep. Keep going Zeph, you might find a recruit one day.
ZoeBell
Jun 02, 2018
This comment has been removed by a moderator.
ZoeBell
Jun 02, 2018
This comment has been removed by a moderator.
RealityCheck
1 / 5 (5) Jun 02, 2018
@jonesdave, @ZoeBell/Zephir).
The XENON WIMPs searches are typical example of wasteful extensive science
As opposed to talking endless crap on a sci-news comments section. Yep. Keep going Zeph, you might find a recruit one day.
@jonesdave. Mate, whatever faults/errors @ZoeBell/Zephir may have/make, he at least tries to keep to the Scientific Method Principle of 'falsification'; to remain alert to flaws in mainstream paradigms/claims etc. While you, @jonesdave, seem to have given up altogether on that Principle; and have become 'a mainstream believer right or wrong!' hack type, doing personal/emotional 'insults battle' with 'perceived cranks' (including me!, who is patently not a 'crank', but merely a dissenting, scrupulously independent, objective observer, following ALL Scientific Method Principles, at all times!). Chill, jd. :)

@ZoeBell/Zephir. Please don't confuse well-observed, increasingly demonstrable Climate Science claims/methodologies, with Cosmology. :)
milnik
1 / 5 (1) Jun 12, 2018
"Dark matter" is a "product" of thoughts, of those people whose consciousness is erased, and consciousness is the power of knowing the true causes of the phenomenon, in general. With Xenon to look for something that nothing is known about, it's an unheard of nonsense. It would be the same if in a dark cave, they dug the earth and asked for gold.
Is it clear to you all that Einstein seized humanity with his theory of relativity and invented the incomprehensible illogicality that space and time "fell in love and married" as two fagots and without that "love curved net" there would be neither gravity nor even human beings of us.
Notice each other, it's time to figure out:
The universe is a sphere of infinite diameter, filled with Aether substance from which matter is formed
milnik
1 / 5 (1) Jun 12, 2018
And matter in two states, together with Aether, causes the appearance of gravity and magnetism. Contaminating and stupid stories are: the phenomenon of BB, the spread of the universe, the dark matter and dark energy, the GW, the black hole collapse, and all the nonsense associated with these fatamagers.
Science does not yet know: how and from what forms matter, how and why gravity and magnetism arise, what is photon, how matter is formed from subatomic particles to clusters of galaxies, science, does not know the laws of motion of matter, and especially celestial bodies. If this is not known, is there anybody normal who will believe in fabrications without this knowledge.

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