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posted by martyb on Wednesday November 27 2019, @02:01AM   Printer-friendly
from the lotsa-little-things-add-up dept.

An international team of researchers has used a new spectrometer to find and set an upper limit for the mass of a neutrino. In their paper published in the journal Physical Review Letters, the group describes how they came up with the new limit...

[...] The researchers carried out their work as part of the Karlsruhe Tritium Neutrino Experiment (KATRIN) on the campus of the Karlsruhe Institute of Technology in Germany. The core piece of equipment used at the site is a 200-ton electron spectrometer. The researchers used it to study the decay of tritium—a radioactive type of hydrogen. When it decays, it emits a single electron and a neutrino at the same time. By measuring the energy of the released electron using the spectrometer, they were able to calculate an estimate of the mass of the neutrino to a greater precision than was possible before. They found its upper limited to be 1.1 electronvolts, approximately half of the previously determined upper limit. It is also extremely tiny—approximately 500,000 times smaller than an electron.

More information: M. Aker et al. Improved Upper Limit on the Neutrino Mass from a Direct Kinematic Method by KATRIN, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.123.221802 . On Arxiv: https://arxiv.org/abs/1909.06048


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  • (Score: 0) by Anonymous Coward on Wednesday November 27 2019, @04:43AM (7 children)

    by Anonymous Coward on Wednesday November 27 2019, @04:43AM (#925260)

    Only in physics do they get to repeat the same experiment dozens of times costing billions of dollars. In other fields, you've got to be re-imagining the platform or driving the AI revolution every fucking 6 months or your funding goes to 24 Chinese post docs and their (also Chinese) supervisor who promised just that. It's a fucking travesty - both situations.

  • (Score: 3, Insightful) by Anonymous Coward on Wednesday November 27 2019, @05:32AM (5 children)

    by Anonymous Coward on Wednesday November 27 2019, @05:32AM (#925267)

    In science, they work to get results as close to conclusive as they can wherever this is possible. If an effect is very small, like the mass of a neutrino or the behaviour of a very short-lived particle, an experiment needs to be repeated many times in order to get the kind of statistical power required to confirm or refute a hypothesis to a certain level of significance. This should ideally be true of all branches of science, but ethical and financial considerations make this infeasible. Getting the kind of five-sigma level of significance that is standard in physics in another branch of science, say, medicine, could actually be even more expensive and fraught with ethical problems. To get five-sigma significance in a randomised clinical trial it would probably have to be an experiment done on at least 3.5 million people. Getting a large city's worth (approximately the population of Berlin) of people involved in a major scientific experiment like that would probably dwarf the cost of the Large Hadron Collider, even if you could convince that many people to participate. They repeat experiments in physics because the increased level of significance they can get is worth the effort. Statistical flukes have happened much to the embarrassment of many an experimental physicist, see for instance the "faster than light neutrinos" reported a few years ago.

    • (Score: 0) by Anonymous Coward on Wednesday November 27 2019, @10:50AM (3 children)

      by Anonymous Coward on Wednesday November 27 2019, @10:50AM (#925305)

      Physics was way better when they tried not to get significance. They are following the rest of science down the toilet.

      • (Score: 2) by PiMuNu on Wednesday November 27 2019, @06:22PM (2 children)

        by PiMuNu (3823) on Wednesday November 27 2019, @06:22PM (#925405)

        > Physics was way better when they tried not to get significance.

        That only works in a paradigm where most phenomena are unexplained. We are now in a paradigm where all known phenomena are explained by the "standard model" and we have to find phenomena that cannot be explained by this model*; which implies looking at rare or challenging-to-measure processes i.e. chasing significance.

        *apart from a few well-known examples e.g. dark matter.

        • (Score: 0) by Anonymous Coward on Wednesday November 27 2019, @07:56PM (1 child)

          by Anonymous Coward on Wednesday November 27 2019, @07:56PM (#925439)

          That is exactly the opposite of reality. When you have a theoretical prediction to test, you try to not get significance, which means your theory is making accurate and useful predictions.

          Although I must say that neither GR nor QM have ever been used to make an useful prediction.

          • (Score: 1, Insightful) by Anonymous Coward on Thursday November 28 2019, @03:27AM

            by Anonymous Coward on Thursday November 28 2019, @03:27AM (#925534)

            Although I must say that neither GR nor QM have ever been used to make an useful prediction.

            Please stop using GPS or other satellite navigation if you really think that general relativity has never made any useful predictions. GPS and other satellite navigation systems make use of the predictions of general relativity to work as well as they do. If they didn't incorporate the predictions of GR (gravitational time dilation for instance), they would give a position that was wrong by several kilometres. More importantly, stop using your computer. Semiconductor components like transistors were developed on the principles of quantum mechanics, which you say hasn't made any useful predictions. The predictions of QM are absolutely fundamental in modern microelectronics.

    • (Score: 1, Insightful) by Anonymous Coward on Wednesday November 27 2019, @10:54AM

      by Anonymous Coward on Wednesday November 27 2019, @10:54AM (#925306)

      Also, the faster than light neutrinos were not a statistical fluke. The statistics correctly told them at least one of the assumptions behind the null hypothesis was wrong... Just like it promised to do.

  • (Score: 3, Touché) by PiMuNu on Wednesday November 27 2019, @12:34PM

    by PiMuNu (3823) on Wednesday November 27 2019, @12:34PM (#925326)

    > In other fields, you've got to be re-imagining the platform or driving the AI revolution every ***ing 6 months

    Good! What would you fund:

    * Measure fundamental constant of nature
    * "Re-imagine the platform"
    * "Drive the AI revolution"

    It turns out that buzzword bingo doesn't get funding...

    > ***ing

    Please don't swear, it is both unnecessary and serves to undermine your point rather than reinforce it.