Researchers present new direct-detection constraints on Sub-GeV dark matter

Researchers present new direct-detection constraints on Sub-GeV dark matter
The detection concept devised by the researchers. Credit: Abramoff et al.

In a recent study, a team of researchers has presented new direct-detection constraints on eV-to-GeV dark matter interacting with electrons, using a new prototype detector developed as part of the Sub-Electron-Noise Skipper-CCD Experimental Instrument (SENSEI) project. The SENSEI collaboration is comprised of researchers from several institutions, including the Fermi National Accelerator Laboratory (Fermilab), the Lawrence Berkeley National Laboratory (Berkeley Lab), Stony Brook University, Tel Aviv University and the University of Oregon.

"SENSEI's goal is to search for dark matter in the mass range 1 eV to 1 GeV, i.e. many orders of magnitude in mass below the proton," Rouven Essig, one of the researchers who carried out the study and a faculty member at Stony Brook University, told Phys.org. "This can be done by searching for dark matter interactions with electrons. However, performing such a search requires ultra-sensitive detectors, since when dark matter scatters off an electron, it produces only a tiny amount of charge in a detector. SENSEI uses Charge Coupled Devices (CCDs) that have an ultra-low readout noise, so-called Skipper-CCDs."

The Skipper-CCDs used by SENSEI were developed as part of an R&D collaboration between Fermilab and Berkeley Lab. In previous studies, the readout noise was a limiting factor, as it restricted the accuracy with which the charge in the CCDs could be measured. The use of new sensors now allows researchers to attain a precise measurement of this charge, which in turn enables a search for dark matter interactions with electrons at unprecedented levels.

Researchers present new direct-detection constraints on Sub-GeV dark matter
The prototype Skipper-CCD used by the researchers. Credit: Abramoff et al.

In their study, the SENSEI Collaboration collected data in the MINOS Hall, a 120-foot-long cavern located 350 feet below the surface of the Fermilab campus. The MINOS cavern contains a smaller version of the MINOS detector in Soudan, which is used to measure the properties of neutrinos.

"We took several sets of data with a small, 0.1 gram, prototype Skipper-CCD at the underground MINOS facility at Fermilab," explained Juan Estrada, a scientist at Fermilab who was involved in the study. "This prototype was packaged and shielded in a copper vessel."

The researchers carried out a series of experiments. Firstly, they read out the Skipper CCD continuously accumulating an exposure of 0.177g/day. Although they observed no events involving three or more electrons, they found a large one- and two- electron background event rate. They attributed this finding to spurious events induced by the amplifier in the Skipper-CCD readout stage.

  • Researchers present new direct-detection constraints on Sub-GeV dark matter
    The prototype Skipper-CCD used by the researchers. Credit: Abramoff et al.
  • Researchers present new direct-detection constraints on Sub-GeV dark matter
    The prototype Skipper-CCD used by the researchers. Credit: Abramoff et al.

The SENSEI Collaboration also tested a second strategy, which involved taking five sets of data while switching off all amplifiers and exposing the Skipper CCD for 120ks. Subsequently, the researchers read out the data via the best prototype amplifier available to them. In this case, they observed a one-electron event rate that was almost 2 orders of magnitude lower than the event rate observed in their continuous-readout experiment. Once again, they observed no events containing three or more electrons, for an exposure of 0.069g/day.

"Our data was able to set new constraints on dark matter, including the best constraints on dark matter scattering of electrons for masses in the range 500 keV to 5 MeV," said Tien-Tien Yu, a faculty member at the University of Oregon who carried out the study. "This data was taken with a prototype detector. One of our main goals was to improve our understanding of the behavior of the detector so that we are ready to collect data with improved sensors in the future."

The SENSEI Collaboration used the data collected in their study to derive world-leading constraints on dark matter-electron scattering (for masses between 500keV and 5MeV), as well as on dark-photon dark matter that is being absorbed by electrons (for a range of masses below 12.4 eV). These results could enhance their understanding of detectors and ultimately inform data collection using more advanced sensors.

Researchers present new direct-detection constraints on Sub-GeV dark matter
The prototype Skipper-CCD used by the researchers. Credit: Abramoff et al.

"We are now procuring new, improved Skipper-CCDs, with which we will build a much larger detector," said Javier Tiffenberg, a scientist at Fermilab who was involved in the study. "After testing the new sensors, we will take new data at Fermilab as well as at SNOLAB (Canada) to search for dark ."

Currently, the SENSEI collaboration is procuring approximately 100g of new Skipper-CCDs and customized electronics for an experiment at SNOLAB, which are set to be installed later this year. According to the researchers' predictions, these sensors should significantly outperform current ones, with an improved noise performance and a lower dark-count rate.

Tomer Volansky, a faculty member at Tel Aviv University who is part of the SENSEI collaboration, stated: "The resulting search will probe orders of magnitude of new parameter space. We are very excited about what lies ahead."


Explore further

The hunt for light dark matter

More information: Orr Abramoff et al. SENSEI: Direct-Detection Constraints on Sub-GeV Dark Matter from a Shallow Underground Run Using a Prototype Skipper CCD, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.122.161801
Journal information: Physical Review Letters

© 2019 Science X Network

Citation: Researchers present new direct-detection constraints on Sub-GeV dark matter (2019, May 13) retrieved 21 May 2019 from https://phys.org/news/2019-05-direct-detection-constraints-sub-gev-dark.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
397 shares

Feedback to editors

User comments

May 13, 2019
We are very excited about what lies ahead...


Gotta love that last quote. Good luck searching excitedly for something that has no proof of existence! Seems like there are many more exciting things to do in life.

May 13, 2019
So, the potential envelope for *local* Dark Matter continues to shrink, raising the uncomfortable possibility that there may be none here-about to be found.
Assuming DM is detectable by this era's physics, What mechanism could remove it ?
Though it is but my amateur hypothesis, I must wonder if our location within the supernova-blown 'Local Bubble' may be responsible.
Due care: such correlation does not imply causation...

May 13, 2019
All assuming DM interacts in some way other than gravitationally

May 13, 2019
Good luck searching excitedly for something that has no proof of existence!


Isn't that kind of the point of science? What's the point of searching excitedly for something which you already have proof exists?

Seems like there are many more exciting things to do in life.

Like sounding ignorant in a physics website comment section.

May 13, 2019
the potential envelope for *local* Dark Matter continues to shrink


Yes, but as Dirk says, only for stuff that interacts (weakly) by EM like WIMPs. The dark matter we see so far is all seen by gravitational interactions.

no proof of existence


No one has philosophical 'proof' of existence, but we can test for dark matter and we have. Here is a method that lets anyone see dark matter with their own eyes: https://galileosp...niverse/ (see the text around the last figure).

We have more proof for its existence than any claim of its non-existence, and claim without evidence can be dismissed without evidence. But those of us who read the science has noted this many times, I assume that was an anti-science troll that was quoted.

May 13, 2019
So, the potential envelope for *local* Dark Matter continues to shrink, raising the uncomfortable possibility that there may be none here-about to be found.
Assuming DM is detectable by this era's physics, What mechanism could remove it ?
Though it is but my amateur hypothesis, I must wonder if our location within the supernova-blown 'Local Bubble' may be responsible.
Due care: such correlation does not imply causation...
says Nik_2213

Well, according to the pseudoscientist, Torbjorn bg Larsson, DM very much exists and may be 'SEEN'. Perhaps Torbjorn has Xray vision like Superman?

"The dark matter we see so far is all seen by gravitational interactions.

No one has philosophical 'proof' of existence, but we can test for dark matter and we have. Here is a method that lets anyone see dark matter with their own eyes: https://galileosp...niverse/ (see the text around the last figure). "

How can anyone knock such a 'genius' who is SOOO positive that DM can be seen?

May 13, 2019
Hmmm I just looked at Torbjorn's link to Genome of the universe.
There is no IMAGE of Dark Matter anywhere on that page. There is only a graph with peaks and valleys supposedly proving the existence of Dark Matter.

Torbjorn insults the readers' intelligence once again in his desperate quest to prove the Dark Matter aficionados right.

May 13, 2019
Hmmm I just looked at Torbjorn's link to Genome of the universe.
There is no IMAGE of Dark Matter anywhere on that page. There is only a graph with peaks and valleys supposedly proving the existence of Dark Matter.

Torbjorn insults the readers' intelligence once again in his desperate quest to prove the Dark Matter aficionados right.
.........no surprise there Egg, that's all Torby does, makes a grandiose statement, & puts up a link that never pans out to whatever he was talking about. He's just schneibo minus 75% of the foul mouthed ranting & sometimes not too far afield of RC. For sure he's never seen a Differential Equation he could solve, right Torby?


May 13, 2019
@Benni, @SEU, @Bart_A,

Something is there; of that there is no doubt. We're just trying to figure out what it is.

May 13, 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
https://www.acade...ilky_Way

May 13, 2019
@Benni, @SEU, @Bart_A,

Something is there; of that there is no doubt. We're just trying to figure out what it is.


Did you read that somewhere?

May 13, 2019
@Benni.
.........no surprise there Egg, that's all Torby does,...sometimes not too far afield of RC...., right Torby?
Actually, mate, Torbjorn and I could not be more "far afield" of each other on many issues; and ESPECIALLY SO when it comes to the claims for 'exotic' DM. :)

By now, Benni, you and everyone else here SHOULD have become unambiguously aware, that:

1) Torbjorn just keeps parroting/supporting the (already increasingly falsified) claim that there is 'exotic' DM;

2) whereas I myself keep pointing out that recent mainstream astro discoveries/reviews are finding more and more vast quantities/distributions of ORDINARY STUFF which was previously too 'dark' to be seen by telescopes when Zwicky first posited that a LOT of 'dunkle' but ORDINARY STUFF was 'out there' affecting the gravitationally-driven motions of stars/galaxies.

And Zwicky was RIGHT!....there IS abundant 'previously dark' matter being found all over...and all of it is of ORDINARY known kinds. :)

May 13, 2019
@observicist.
@Benni, @SEU, @Bart_A,
Something is there; of that there is no doubt. We're just trying to figure out what it is.
Please read my post to @Benni; pointing out we NOW DO know what that previously-invisible 'dark matter') is....because it is now increasingly being found in VAST quantities all over in space...and it is all ordinary stuff, not 'exotic' as still being claimed by those who haven't yet 'connected the dots' of recent/ongoing astronomical discoveries/reviews.

So the REAL 'mystery' is why anyone still claims to "not know" that the actual (previously dark) matter is merely the previously undetectable (but now increasingly detectable with new scopes etc) ORDINARY known gravitationally-AND-electromagnetically-interacting kinds of matter which ZWICKY originally posited; but which original posit was later 'twisted' (by incompetent and metaphysics-promulgating BB fantasist-theorists) into imaginary 'exotic' DM that did not interact electromagnetically. :)

May 13, 2019
Well, I'm with these research guys all the way and they get my vote. Now maybe it will provide some info on DM and maybe it won't but such technological innovation will probably be useful elsewhere in science. Isn't that what science is all about too? Maybe DM will turn out to be good old fashioned 'cheese' and maybe it will be something that will help usher in some new or additional, physics. The point is to maintain the enthusiasm and curiosity to find out what is causing the observed effect.

May 13, 2019
Skipper CCDs present new opportunities for observation, not only of dark matter events but also for general astrophysics and astronomy.

Ordinary CCDs shuffle the electrons out of a row into a single column by passing them through each pixel, then shuffle the column out to an amplifier for readout. The collected electrons in modern CCDs closely approximate the observed photons; the efficiency is usually quoted, called "quantum efficiency," and modern CCDs show quantum efficiencies well in excess of 99%. These have been in use since the late 1990s; you can buy commercial CCD SLRs with efficiencies like this, and astronomical CCDs that are much higher. These are in widespread use at observatories throughout the world, and some with a bit lower sensitivity (and therefore much lower cost) are in use by amateur astronomers over an even wider distribution. I actually happen to own one (a traditional CCD with high quantum efficiency, not a Skipper- I couldn't afford that).

[contd]

May 13, 2019
And Zwicky was RIGHT!....there IS abundant 'previously dark' matter being found all over...and all of it is of ORDINARY known kinds. :)
.......ok, maybe you think there are orders of magnitude between you & Torby, but this persistent slop & swill psycho-babble that goes on about this absolutely stupid Cosmic Fairy Dust is the furthest from discovery as it has ever been.

Zany Zwicky promoted huge halos of this stuff that by the middle of the last century astrononers were stating that it was completely encompassing every Spiral Galaxy in existence to keep them from either flying apart or imploding, instead all we keep finding in those regions are more & more hydrogen, hardly "dark" & never missing.

May 13, 2019
[contd]
Now, there are two problems with this: all this shifting around is bound to introduce quantum noise, and when a readout occurs, all the values in the entire device are destroyed. And in order to read a single pixel, all of the values must be destroyed.

The Skipper CCD concept allows any pixel in the CCD array to be non-destructively read, if I understand it correctly. This makes it possible to expose the CCD, then make multiple readouts of each cell and average them, giving a more accurate value. What these guys are fighting is amplifier noise in the readout amplifier. Their initial results are very promising.

May 13, 2019
And Zwicky was RIGHT!....there IS abundant 'previously dark' matter being found all over...and all of it is of ORDINARY known kinds. :)
.......ok, maybe you think there are orders of magnitude between you & Torby, but this persistent slop & swill psycho-babble that goes on about this absolutely stupid Cosmic Fairy Dust is the furthest from discovery as it has ever been.

Zany Zwicky promoted huge halos of this stuff that by the middle of the last century astrononers were stating that it was completely encompassing every Spiral Galaxy in existence to keep them from either flying apart or imploding, instead all we keep finding in those regions are more & more hydrogen, hardly "dark" & never missing.
says Benni

I for one, am still happy at knowing the theory of "Mirror Matter" aka "Mirror Dark Matter
that explains the symmetry of normal Matter; that symmetry that includes all particles and waves that are the mirror image of normal matter. I'm going with it.

May 13, 2019
@Benni

I hope to be in touch with Dr. Robert Foot of Melbourne U in Australia to see how well his/their research is coming along with the "Mirror Matter" theory.
To me, the theory seems to be the closest to what Dark Matter halos are all about. I don't see that there is any better explanation for Particle Symmetry (my words).
Any suggestions?

https://en.wikipe...r_matter


May 14, 2019
On Symmetries - left handed. right handed

https://www.nap.e...hapter/5


May 14, 2019
If the technology is eve invented to make possible for us to "see"/"image"/"observe" Gravity?
I think DM will turn out, all of it, to be gravitrons.

May 14, 2019
A couple things.

They're gravitons, not gravitrons.

They're like 10^47 smaller than photons, and we have enough trouble trying to detect individual photons.

They're massless (move at the speed of light) so neither dark matter nor dark energy is going to turn out to be gravitons.

Carry on.

May 14, 2019
We are very excited about what lies ahead...


Gotta love that last quote. Good luck searching excitedly for something that has no proof of existence! Seems like there are many more exciting things to do in life.


wit brains like yours the neutrino would remain ghostly and undiscovered.

May 14, 2019
We are very excited about what lies ahead...


Gotta love that last quote. Good luck searching excitedly for something that has no proof of existence! Seems like there are many more exciting things to do in life.


wit brains like yours the neutrino would remain ghostly and undiscovered.

Not quite. At least with neutrinos you can create a device and experiments to detect them. So far, no such luck with dm (because it doesn't exist).

May 14, 2019
@Benni

I hope to be in touch with Dr. Robert Foot of Melbourne U in Australia to see how well his/their research is coming along with the "Mirror Matter" theory.
To me, the theory seems to be the closest to what Dark Matter halos are all about. I don't see that there is any better explanation for Particle Symmetry (my words).
Any suggestions?
......never heard of it till you brought it up. I don't understand why the Universe needs a RIGHT & LEFT Hand.


May 14, 2019
@eggshit

Why doesn't Dr Robert Ford show up in a google search is he shy?

May 14, 2019
Not quite. At least with neutrinos you can create a device and experiments to detect them. So far, no such luck with dm (because it doesn't exist).


And all the cranks* thought the neutrino would never be detected. And that, subsequently, that neutrino oscillation wouldn't be found. They claimed that gravitational wave detectors were a waste of money, because GWs didn't exist. They claimed neutron stars were impossible. They claimed black holes were impossible. Guess what? The cranks are getting painted into a smaller and smaller corner. Want to bet against them detecting DM?

*Mostly referring to the unscientific electric universe idiots.

May 14, 2019
@eggshit

Why doesn't Dr Robert Ford show up in a google search is he shy?
says hatshit1208

Who is Dr Robert Ford? I have no idea who you're talking about. Stop talking gibberish.

May 14, 2019
We are very excited about what lies ahead...


Gotta love that last quote. Good luck searching excitedly for something that has no proof of existence! Seems like there are many more exciting things to do in life.


wit brains like yours the neutrino would remain ghostly and undiscovered.

Not quite. At least with neutrinos you can create a device and experiments to detect them. So far, no such luck with dm (because it doesn't exist).
says arcmetal

Neutrinos appear to be particles. But the pseudogenius Castrovagina should know all about them so as to elaborate on the subject handily without even referring to the literature or consulting with the pseudoscientist from Sweden.
Dark Matter is a blurb that should have been entitled "Mirror Matter" as all quantum particles are symmetrical in nature, not asymmetric. Asymmetric would mean only left-handedness, a state of matter that cannot exist. Matter requires both left & right handedness

May 14, 2019
Not quite. At least with neutrinos you can create a device and experiments to detect them. So far, no such luck with dm (because it doesn't exist).


And all the cranks* thought the neutrino would never be detected. And that, subsequently, that neutrino oscillation wouldn't be found. They claimed that gravitational wave detectors were a waste of money, because GWs didn't exist. They claimed neutron stars were impossible. They claimed black holes were impossible. Guess what? The cranks are getting painted into a smaller and smaller corner. Want to bet against them detecting DM?

*Mostly referring to the unscientific electric universe idiots.
says Castrovagina

Just WHO are these 'cranks' of whom you speaketh, jonesy?
Do name them so that we all can know who they are. I know of quite a few here in physorg who still haven't recognised themselves as "cranks" while they are calling other folks 'cranks'.
-contd-

May 14, 2019
-contd-
@CastroVagina alias jonesy

You see jonesy, one of the ways to be a crank is to think your schitt doesn't stink while you are referring to others as "cranks" who may only be offering their opinions, ideas, hypotheses and such in a science website such as physorg, whose primary purpose is to offer science articles which may or may not have any true scientific value. I have read both types of articles - those that have absolute scientific merit, and those who don't.
But they are ALL presented here in physorg and other websites for the readership to ponder over and then make their opinions known in the phorums.
Sometimes the comments have merit and new ideas/opinions are brought forth so that all may chew on it a bit. But in the long run, it is not YOU or the Swede or DS who determines if those ideas have merit or not, it is the scientists who are doing the experiments who make that determination. All THEY can do is take the time to read the opinions here, is all.

May 14, 2019
@Benni

I hope to be in touch with Dr. Robert Foot of Melbourne U in Australia to see how well his/their research is coming along with the "Mirror Matter" theory.
To me, the theory seems to be the closest to what Dark Matter halos are all about. I don't see that there is any better explanation for Particle Symmetry (my words).
Any suggestions?
......never heard of it till you brought it up. I don't understand why the Universe needs a RIGHT & LEFT Hand.

says Benni

The proponents of Zwickian "Dark Matter" are legion, both in physorg and in the halls of academia.
Such strong opinion AND fervour FOR Dark Matter/halo that is almost to the point of insanity is the problem in this particular field of science. It is similar to the Third Reich madness that enveloped the German psyche in WW2 and prior when they would not think of any other alternative.
Thus the alternative of "Mirror Matter" is not as popular at present, and it must be proven by more experiments.

May 14, 2019
-contd-
@Benni

Left handedness by itself (asymmetry) is unnatural in the quantum universe. There has to BE left and right handedness to stabilise all Matter/Energy down to the tiniest sub-sub-sub-particle. Otherwise, you have utter chaos with 'things' not working right. Even your Laws of Thermodynamics would be unworkable with only a left-handedness in the quantum universe. It would continue on up into the macro Universe where everything that you SEE would be in total disarray, broken, and life itself would not exist. It is that left and right handedness as the mirror image of each particle that enables Matter to exist. As well as Life.
Don't knock it. Scientists are working on proving the theory of Mirror Matter aka Mirror Dark Matter. Give them time to work it out, Benni. Read the literature and learn about it. It is real.

May 14, 2019
Scientists are working on proving the theory of Mirror Matter aka Mirror Dark Matter. Give them time to work it out, Benni.
......to me things are unworkable without ENTROPY whereas mirrors are reflections, I can function pretty well all the day long without having to look in one.....I'm that good lookin', especially when the wind tossels my hair in a gentle breeze & the ladies look my way........ I wouldn't want competition from a doppleganger , or whatever might be on the other side.


May 14, 2019
Scientists are working on proving the theory of Mirror Matter aka Mirror Dark Matter. Give them time to work it out, Benni.
......to me things are unworkable without ENTROPY whereas mirrors are reflections, I can function pretty well all the day long without having to look in one.....I'm that good lookin', especially when the wind tossels my hair in a gentle breeze & the ladies look my way........ I wouldn't want competition from a doppleganger , or whatever might be on the other side.
says Benni

LOL Benni, If you keep talking like that about your looks, Da Schneibo or kl31415 might take a fancy to you.
In the macro Universe, there is Entropy, that is unchangeable. BUT, it all starts in the quantum universe (which is quite large for something so tiny). The left and right handedness of Mirror Matter isn't like looking in a mirror exactly. It is the 'mirror image' of EACH PARTICLE that stabilises each particle.

May 14, 2019
Scientists are working on proving the theory of Mirror Matter aka Mirror Dark Matter. Give them time to work it out, Benni.


.....to me things are unworkable without ENTROPY whereas mirrors are reflections, I can function pretty well all the day long without having to look in one.....I'm that good lookin', especially when the wind tossels my hair in a gentle breeze & the ladies look my way........ I wouldn't want competition from a doppleganger , or whatever might be on the other side.
says Benni

LOL Benni, If you keep talking like that about your looks, Da Schneibo or kl31415 might take a fancy to you.
.....my wife tells me she's not worried about someone else interloping on her, that I already full well know she's irreplaceable no matter how many passes she observes other women making at me, of course the only "passes" I observe are the ones other men make at her.


May 14, 2019
-contd-
@Benni
These links may help. Explains far better than I can. :)

https://phys.org/...ate.html
......a lot of heavily laden quark theory stuff. Quarks have never been isolated making Foot safe from being my doppleganger, just don't tell schneibo, I suspect he has had other high hopes & would become jealous. :-)

May 14, 2019
-contd-
@Benni
These links may help. Explains far better than I can. :)

https://phys.org/...ate.html
......a lot of heavily laden quark theory stuff. Quarks have never been isolated making Foot safe from being my doppleganger, just don't tell schneibo, I suspect he has had other high hopes & would become jealous. :-)


I strongly suspect that nothing will sway the minds of these folks from their beloved Zwickian Dark Matter in favour of a new theory such as Mirror Dark Matter, no matter how strong the evidence is for MDM. There is possibly a psychological reason for their bitter clinger behaviour when anything is said that belittles Zwicky in any way, shape or form.
Quarks, leptons...any type of particle would be left handed, but with the addition of a right handed "twin". I say twin for the simple reason that the right hand is the exact opposite of the left handed particle. There's your Dark Matter that you can't see.

May 14, 2019
What amazes me is that the article is about a new application enabled by a new technology, and all the trolls can think to do is deny dark matter. They don't even have a single idea about how it works, and they're not interested. They're not here to argue science; they're here to obstruct it. They fear it.

Nothing more need be said.

May 14, 2019

@Benni
These links may help. Explains far better than I can. :)

https://phys.org/news/2010-04-dark-mirror-candidate.html
......a lot of heavily laden quark theory stuff. Quarks have never been isolated making Foot safe from being my doppleganger, just don't tell schneibo, I suspect he has had other high hopes & would become jealous. :-)


Quarks, leptons...any type of particle would be left handed, but with the addition of a right handed "twin". I say twin for the simple reason that the right hand is the exact opposite of the left handed particle. There's your Dark Matter that you can't see.
.........then they need to first come up with the left handed before they can even speculate the right, which I guess was one of the things the LHC was supposed to do but has failed to isolate the first quark.

May 14, 2019
They're not here to argue science; they're here to obstruct it. They fear it.
.......so why then do you have such a rabid fear of the Inverse Square Law & persistently try subjecting an EM Wave to the Laws for Kinetic Energy Escape Velocity? Talk about being a "science obstructionist", you're the epitome of all the things you complain about.

May 14, 2019
I'll say that I think people who deny science are evil.

You can deny it all you like, but it remains true.

Evil always denies truth.

May 14, 2019

@Benni
These links may help. Explains far better than I can. :)

https://phys.org/...ate.html
......a lot of heavily laden quark theory stuff. Quarks have never been isolated making Foot safe from being my doppleganger, just don't tell schneibo, I suspect he has had other high hopes & would become jealous. :-)


Quarks, leptons...any type of particle would be left handed, but with the addition of a right handed "twin". I say twin for the simple reason that the right hand is the exact opposite of the left handed particle. There's your Dark Matter that you can't see.
.........then they need to first come up with the left handed before they can even speculate the right, which I guess was one of the things the LHC was supposed to do but has failed to isolate the first quark.
says Benni

The left-handed particles exist already. It was the asymmetry of those particles that was the problem that needed a solution.

May 14, 2019
@Benni

We know already that Nature mirrors a lot of 'things'. Plants seeds come in two sections, body parts such as lungs, kidneys, eyes, hands/arms, legs, etc. come in twos, the heart even has 2 atrium and 2 ventricles side by side. So twinning is natural. And its the same with quantum particles where there are TWO 'sections' that are the exact opposite - the left and the right sides.
The hidden Matter is made up of each particle's twin. Some one asked about the EM. Well, the EM also has its own opposite. It's not antimatter, however, but a mirror image of the normal particle or energy. That is my understanding.

May 15, 2019
The Skipper CCD concept allows any pixel in the CCD array to be non-destructively read, if I understand it correctly.
So it would seem; and, as you say, they will have to do more work on minimizing amplifier noise, but the strategy of leaving the amps switched off for a long period and then reading out the pixels has bought them a couple of orders of magnitude better S/N.

I still don't get, however, the "gram/day" measurement: isn't that a bit like saying my automobile can do 2 tons/day? Why don't they quote something more useful like events/pixel/day as in the paper? Perplexed.

May 15, 2019
Plants seeds come in two sections
- this is only true for dicotyledons (many flowering plants and trees). It's not true, however, for monocotyledons - grasses, rice, wheat, maize and also orchids, lilies, bananas, ginger, asparagus, pineapples, onions and many more.


So twinning is natural
Occasionally, yes.


And its the same with quantum particles where there are TWO 'sections' that are the exact opposite - the left and the right sides
You may wish it were so for the sake of your "argument", but it's only true for particles with rest mass - electrons, quarks and neutrinos, where the particle's spin may be parallel or antiparallel to the direction of motion of the particle. Left- and right-handedness in this context refer, by convention only, to parallel and antiparallel spin alignments.

Learn some physics and math (you also evidently need a refresher course in biology), and get your facts right.

[tbc]

May 15, 2019
[continued]

Some one asked about the EM. Well, the EM also has its own opposite. It's not antimatter, however, but a mirror image of the normal particle or energy
Meaningless word-salad: asking you about anything scientific would be like asking a chimp to explain the rules of cricket. Who in their right mind would do such a thing? (See below)

For your information, photons, and the other massless particles gluons and gravitons, can only have their spin parallel to their direction of motion; also they have no charge, which means that e.g. a photon is its' own antiparticle. See e.g. https://van.physi...?id=1153

No "mirror images" anywhere here, although you seem to want there to be. Making shit up out of thin air might impress your fellow members of the Four-And-A-Half Stooges comedy club, but it's light-years away from being even remotely scientifically accurate or meaningful.

Learn some physics and math, and get your facts right.

May 15, 2019
Oops - I got the handedness the wrong way around. Here we go: "The helicity of a particle is right-handed if the direction of its spin is the same as the direction of its motion (parallel). It is left-handed if the directions of spin and motion are opposite (antiparallel)".


May 15, 2019
According to Wikipedia:
Exposure, in physics (in particular beam experiments or flux measurements), the product of the detector mass times the duration of the experiment, sometimes also multiplied by a measure of the intensity of the incoming flux
It is therefore detector mass times the duration of the experiment, in gram-days. That's how come they keep referring to the mass of the detectors through the rest of the article, and in the abstract to the paper, too.

Here's the link to the Wikipedia article: https://en.wikipe...Exposure

On edit, this does seem like a good way to characterize detectors for things like this. How much detector mass you have determines how likely you are to see events, and so does how long you run the detector.

May 15, 2019
this does seem like a good way to characterize detectors for things like this. How much detector mass you have determines how likely you are to see events
I get that for a detector made, say, from a solid lump of something special like niobium nitride or whatever - the more detector material you have, the more events you're likely to detect, and also cross-sectional area plays a part.

But to my mind, it makes rather less sense to use this mass/time relationship for a matrix of electronic sensors, where the mass of detector material, or even the type of material itself, per pixel might change over distinct developmental generations of detector. So it looks like they're just using a convention from (somewhat) similar type of detection technologies. Still sounds kinda strange, though.

May 15, 2019
Well, I dunno how special you wanna get but seems to me that CCD silicon, particularly when all dolled up with this Skipper thing and a bunch of super amplifiers, is pretty special. I expect they're applying a formula to measure the amount of silicon, or perhaps even the total mass of the electrons in it, that we can't see because it's in the text of the paper and AFAICT it's not available publicly.

May 15, 2019
Something to keep in mind here: this is a bit different from the various xenon and other exotic element detectors. Instead of watching for events in some separate substrate, these folks are watching for events that actually occur in the detector. So that might have something to do with why they grade it in terms of exposure.

May 15, 2019
these folks are watching for events that actually occur in the detector.
Well, yes, it's a kind of super CCD, where event-counts are stored in each "pixel", but which don't get destroyed in read-out.

Paper is at https://arxiv.org...0478.pdf

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more