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Science

Massive, Blimplike Experiment Lowers Weight Limit On Neutrino (sciencemag.org) 59

Posted by BeauHD from the greater-than-or-equal-to dept.
sciencehabit shares a report from Science Magazine: Physicists have set a new limit on the mass of nature's lightest particle of matter. The neutrino can weigh no more than 1.1 electron volts (eV) -- less than one-500,000th the mass of an electron -- say experimenters with the Karlsruhe Tritium Neutrino (KATRIN) experiment at the Karlsruhe Institute of Technology in Germany. Reported on September 13 at a meeting in Toyama, Japan, the new result halves the previous limit of 2 eV.

Physicists have tried to measure the neutrino's mass for decades. However, the particle barely interacts with ordinary matter. So to deduce its mass, researchers study the radioactive "[Beta] decay" of tritium, in which a nucleus spits out an electron and a neutrino. By precisely measuring the maximum energy of the ejected electrons, physicists can infer the mass of the unobserved neutrinos. KATRIN (above) takes this classic approach to the ultimate limit, employing a 23-meter-long blimplike spectrometer to measure the electron from tritium with unprecedented precision. Cosmological measurements already suggest the neutrino cannot weigh more than about 0.1 eV, but that estimate is based on several assumptions. So KATRIN physicists argue that their better, directly measured limit on neutrino mass is likely to make cosmology models more reliable.
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Massive, Blimplike Experiment Lowers Weight Limit On Neutrino More

Massive, Blimplike Experiment Lowers Weight Limit On Neutrino

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  • I knew it (Score:3, Funny)

    by 110010001000 ( 697113 ) on Wednesday September 18, 2019 @09:14AM (#59208042) Homepage Journal

    I knew the mass of a neutrino was much larger than the 0.1eV promoted by the "cosmological establishment". This will wipe the smugness right off their faces. It also explains what the missing mass now explained as "Dark Matter" is. Do you know how I know all this? I am an expert, for I read Slashdot and comment in the comment section.

    • Re:I knew it (Score:5, Insightful)

      by OneHundredAndTen ( 1523865 ) on Wednesday September 18, 2019 @09:25AM (#59208088)
      The experiment just concludes that its mass can't be larger than 1.1 eV. It says nothing about how light it could be. For all we know, that mass posited by cosmological arguments may still be right. You are jumping the gun.

      • Unpossible. Slashdot commenters never jump the gun. We always make seasured thoughtful responses to every scientific discovery.

        • "We always make seasured thoughtful responses to every scientific discovery."

          I think you may be having a seasure right now!

          • I meant to say "measure". I might have jumped the gun on my comment and didn't carefully read my response. At least I get a Christmas bonus.

            • It's almost as if you started writing seasoned, but switched mid-word! And Christmas is in a few months, maybe I can buy you a t-shirt with a joke about cookies on it?

    • Donâ(TM)t believe it (Score:5, Funny)

      by llZENll ( 545605 ) on Wednesday September 18, 2019 @10:16AM (#59208294)

      My girlfriend is a Cosmologist and uses Nuetrogena on her customers everyday. It seems like it weighs a normal amount, of course they are on the ground and not in a blimp so maybe that has something to do with it :/

    • You OK man? Things getting to you lately? Maybe take some time off the internet?

      • Yeah, I need time to pack my bags for Mars. When are we leaving?

        • The great news is we have the technology to leave for Mars any time. Getting there, living there and coming home are some of the little details being worked out.

          • Yes but we’ve had that for decades. The trifling details of getting people there alive and living there is so minuscule, I’m sure they’ll figure that out any day now.

          • Ah, well I have my bags packed and ready by the door. Once Elon gets his rocket ready I will be first on board. I need to get off this rock stuck in a gravity well filled with boorish humans. So long, suckers!

        • We aren't perfect enough for you, and we never can be. Don't come back.

          • What? I am sure a Space Nutter like you will be first in line for Mars. Right? We can hang out together and laugh at tll the poor huddled Earth masses. Why fix Earth when you can just dream of leaving it!

            • I don't even understand what you're trying to say. But please leave us, you obviously hate us and we can never meet your exacting standards. Have you considered emigration?

          • Quite an ironic comment considering your sig.

            • Who stopped anyone from speaking with violence? Hearing obviously wrong opinions is valuable as we can point out where they're wrong. Censoring just shows how fragile and indefensible your own opinions are.

              • Excluding people from a place you frequent based on their opinions is exclusionary and you are impinging on our freedom to associate.

                • You're just being shown the door due to your odious opinions. Nobody likes you, and you're free to shout it on the street. Just not on any platform we control.
    • Since when have cosmologists said that definitively it was 0.1eV? The only source [fnal.gov] I could find says differently

      The current best estimate says that the sum of the masses of the three neutrinos should be below about one electronvolt.

      The words you should pay attention to are “best estimate” meaning it isn’t definitive.

      • Oh, they say it all the time at the cocktail parties with the smug grins on their faces. Damn Cosmologists.

        • Really? So your source isn’t a paper or conference but said to you by unnamed cosmologists at some party that no one can verify. Perhaps at these cocktail parties, your recall may have been affected by cocktails?

          • Well I could tell you my sources, but Big Cosmology will hunt me down and kill me so I would rather not.

            • Sure, you can’t tell me a paper or conference because you’re paranoid someone will keep you from divulging publicly available information. Do you have a newsletter? I wish to subscribe.
    • Spin this into a theory with math that doesn't even have to make sense, and you probably qualify for a government grant somewhere.

      • My paper on Neutrino Mass and Superstring Theory is already in pre-print.

      • Re: (Score:2)

        by gtall ( 79522 )

        Actually DoE, DoD, and NSF grants are quite competitive. Stop bad-mouthing the Fed. Gov. because you like to repeat the right-wing echo chamber.

    • "PI day is just a conspiracy by Big Math to sell more Math".
  • Comment removed based on user account deletion

    • We know that neutrinos oscillate, so the mass MUST be > 0.
      But are there any experiments that establish a lower limit?

      Sure -- they have to have mass > 1 Planck mass. Scratch that - turns out there actually is such a unit & it's way big.

      OK, minimum mass of a neutrino is equivalent to a cube of pure water (no deuteration) one Planck-length on a side.

    • We know that neutrinos oscillate, so the mass MUST be > 0.

      But are there any experiments that establish a lower limit? If so, what are they?

      I'm unaware of any lower limit, other than "more than zero".

      It the rest mass were zero, like a photon, they would travel at the speed of light. Then they would experience no time in which to perform oscillations. But absent any clue about how much time is needed to change flavor, you have no clue about how MUCH less than c they'd have to move to make the change in t

      • You know their total energy, ...

        Actually, you know their momentum and the current experiments are about figuring out the total energy so you can assign to excess to rest mass.

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