New World Record: “Ghost Particle” Experiment Limits Neutrino Mass With Unprecedented Precision

Particle Collision Neutrino Concept

Neutrinos Are Lighter Than 0.8 Electronvolts

New world record: KATRIN experiment limits neutrino mass with unprecedented precision.

Neutrinos are arguably the most fascinating elementary particle in our universe. In cosmology they play an important role in the formation of large-scale structures, while in particle physics their tiny but non-zero mass sets them apart, pointing to new physics phenomena beyond our current theories. Without a measurement of the mass scale of neutrinos, our understanding of the universe will remain incomplete.

Scientists often refer to the neutrino as the ​“ghost particle” because they almost never interact with other matter.

This is the challenge the international KArlsruhe TRItium Neutrino (KATRIN) experiment at Karlsruhe Institute of Technology (KIT) with partners from six countries has taken up as the world´s most sensitive scale for neutrinos. It makes use of the beta decay of tritium, an unstable hydrogen isotope, to determine the mass of the neutrino via the energy distribution of electrons released in the decay process. This necessitates a major technological effort: the 70 meter long experiment houses the world´s most intense tritium source as well as a giant spectrometer to measure the energy of decay electrons with unprecedented precision.

KATRIN Main Spectrometer

Mounting of electrodes in the main spectrometer of the KATRIN experiment. Credit: Joachim Wolf/KIT

The high quality of the data after starting scientific measurements in 2019 has continuously been improved over the last two years. “KATRIN is an experiment with the highest technological requirements and is now running like perfect clockwork” enthuses Guido Drexlin (KIT), the project leader and one of the two co-spokespersons of the experiment. Christian Weinheimer (University of Münster), the other co-spokesperson, adds that “the increase of the signal rate and the reduction of background rate were decisive for the new result.”

Data analysis

The in-depth analysis of this data was demanding everything from the international analysis team led by its two coordinators, Susanne Mertens (Max Planck Institute for Physics and TU Munich) and Magnus Schlösser (KIT). Each and every effect, no matter how small, had to be investigated in detail. “Only by this laborious and intricate method we were able to exclude a systematic bias of our result due to distorting processes. We are particularly proud of our analysis team which successfully took up this huge challenge with great commitment,” the two analysis coordinators are pleased to report.

KATRIN Experiment Setup

The 70 meter long KATRIN experiment with its main components tritium source, main spectrometer and detector. Credit: Leonard Köllenberger/KATRIN Collaboration

The experimental data from the first year of measurements and the modeling based on a vanishingly small neutrino mass match perfectly: from this, a new upper limit on the neutrino mass of 0.8 eV can be determined (Nature Physics, July 2021). This is the first time that a direct neutrino mass experiment has entered the cosmologically and particle-physically important sub-eV mass range, where the fundamental mass scale of neutrinos is suspected to be. “The particle physics community is excited that the 1-eV-barrier has been broken by KATRIN,” comments neutrino expert John Wilkerson (University of North Carolina, Chair of the Executive Board).

Susanne Mertens explains the path to the new record: “Our team at the MPP in Munich has developed a new analysis method for KATRIN that is specially optimized for the requirements of this high-precision measurement. This strategy has been successfully used for past and current results. My group is highly motivated: We will continue to meet the future challenges of KATRIN analysis with new creative ideas and meticulous accuracy.”

Further measurements should improve sensitivity

The co-spokespersons and analysis coordinators of KATRIN are very optimistic about the future: “Further measurements of the neutrino mass will continue until the end of 2024. To realize the full potential of this unique experiment, we will not only steadily increase the statistics of signal events, we are continuously developing and installing improvements to further lower the background rate.”

The development of a new detector system (TRISTAN) plays a specific role in this, allowing KATRIN from 2025 on to embark on a search for “sterile” neutrinos with masses in the kiloelectronvolt-range, a candidate for the mysterious dark matter in the cosmos that has already manifested itself in many astrophysical and cosmological observations, but whose particle-physical nature is still unknown.

Reference: “Direct neutrino-mass measurement with sub-eV sensitivity” by The KATRIN Collaboration, 14 February 2022, Nature Physics.
DOI: 10.1038/s41567-021-01463-1

6 Comments on "New World Record: “Ghost Particle” Experiment Limits Neutrino Mass With Unprecedented Precision"

  1. Interesting.
    Some Thoughts
    1. Neutrino. Has Mass. The Missing Link between Mass and Energy?
    2. Most Periodic Element Tables have fractional atomic mass. except a few like Einstienium,Lawrencium in Actinides. We use unstable Isotopes of Actinides for Fission Energy. From Atomic No. 104 to118 atomic number 118 the elelemts have atomic mass which are whole numbers, but the masses seem Odd as they increase and decrease without adiscernible pattern.
    3. Neutrinos hold the Universe Together, in its Eqilibrium State between Energy and Matter.
    4. So logically the Neutrino may have a role to play in creation of Elements and holding the same together as well. There are probably countless Free Neutrinos floating in the Universe and passing through all Matter -Energy states once created , as if neither exists. It is Ubiquitous.
    5. It may be the very Glue which enables creation of Matter from Energy and also Energy from Matter. Matter so created may be stable or unstable depending on the strength of the bonding between positive sub atomic particles and negative sub- atomic particles.
    6. Matter once created , results in the force of Gravity in the Gross Real World, of Stars and planets,moons,,asteroids and other bodies.

    Views and Hypothesis proposed are personal and not binding onanyone.

  2. BibhutibhusanPatel | February 14, 2022 at 9:04 pm | Reply

    The mass of neutrino is corelated to the mass of Higgs boson.The context of dark matter is different.Likely sterile neutrino,which has no need to exist.Thanks to the authors for calculating mass of the neutrino,.8 eV.

  3. BibhutibhusanPatel | February 14, 2022 at 9:17 pm | Reply

    The mass of neutrino is corelated to the mass of Higgs boson.The context of dark matter is different.Likely sterile neutrino,which has no need to exist.Thanks to the authors for calculating mass of the neutrino,.8 eV.

    These results are all leading to fundamental base of physics including the astrophysics.Unified Common Field Theory has a strong ground.

  4. Babu G. Ranganathan | February 15, 2022 at 8:39 am | Reply

    Babu G. Ranganathan*
    (B.A. Bible/Biology)

    JUST BECAUSE SCIENCE CAN EXPLAIN how an airplane works doesn’t mean that no one designed or made the airplane. And just because science can explain how life or the universe works doesn’t mean there was no Designer and Maker behind them.

    Natural laws may explain how the order in the universe works and operates, but mere undirected natural laws cannot explain the origin of that order. Once you have a complete and living cell then the genetic code and biological machinery exist to direct the formation of more cells from raw materials such as amino acids and other chemicals, but how could life or the cell have naturally originated when no directing code and mechanisms existed in nature? Read my Internet article: HOW FORENSIC SCIENCE REFUTES ATHEISM.

    WHAT IS SCIENCE? Science simply is knowledge based on observation. No human observed the universe coming by chance or by design, by creation or by evolution. These are positions of faith. The issue is which faith the scientific evidence best supports.

    SCIENCE SHOWS THAT THE UNIVERSE CANNOT BE ETERNAL because it could not have sustained itself eternally due to the law of entropy (increasing and irreversible net energy decay, even in an open system). Even a hypothetical oscillating universe could not continue to oscillate eternally! Einstein’s General Theory of Relativity shows that space, matter, and time all are physical and all had a beginning. Space even produces particles because it’s actually something, not nothing. What about the Higgs boson (the so-called “God Particle”)? The Higgs boson, even if it existed, would not have created mass from nothing, but rather it would have converted energy into mass. Einstein showed that all matter is some form of energy. Even time had a beginning! Time is not eternal.

    The law of entropy doesn’t allow the universe to be eternal. If the universe were eternal, everything, including time and space (which modern science has shown are as physical as mass or matter), would have become totally entropied by now and the entire universe would have ended in a uniform heat death a long, long time ago. The fact that this hasn’t happened already is powerful evidence for a beginning to the universe.

    Popular atheistic scientist Stephen Hawking admits that the universe had a beginning and came from nothing but he believes that nothing became something by a natural process yet to be discovered. That’s not rational thinking at all, and it also would be making the effect greater than its cause to say that nothing created something. The beginning had to be of supernatural origin because science teaches us from the First Law of Thermodynamics that natural laws and processes do not have the ability to bring something into existence from nothing.

    The supernatural origin of the universe cannot be proved by science but science points to a supernatural intelligence and power for the origin and order of the universe. Where did God come from? Obviously, unlike the universe, God’s nature doesn’t require a beginning.

    The disorder in the universe can be explained because of chance and random processes, but the order can be explained only because of intelligence and design.

    Gravity may explain how the order found in the precise and orderly courses of thousands of billions of stars is maintained, but gravity cannot explain the origin of that order.

    Some evolutionary astronomers believe that trillions of stars crashed into each other leaving surviving stars to find precise orderly orbits in space. Not only is this irrational, but if there was such a mass collision of stars then there would be a super mass residue of gas clouds in space to support this hypothesis. The present level of residue of gas clouds in space doesn’t support the magnitude of star deaths required for such a hypothesis. And, as already stated, the origin of stars cannot be explained by the Big Bang because of the reasons mentioned above. It’s one thing to say that stars may decay and die into random gas clouds, but it is totally different to say that gas clouds form into stars.

    Even the father of Chaos theory admitted that the “mechanisms” existing in the non-living world allow for only very rudimentary levels of order to arise spontaneously (by chance), but not the kind or level of order we find in the structures of DNA, RNA, and proteins. Yes, individual amino acids have been shown to come into existence by chance but not protein molecules which require that the various amino acids be in a precise sequence just like the letters found in a sentence.

    Some things don’t need experiment or scientific proof. In law there is a dictum called prima facie evidence. It means “evidence that speaks for itself.”

    An example of a true prima facie would be if you discovered an elaborate sand castle on the beach. You don’t have to experiment to know that it came by design and not by the chance forces of wind and water.

    If you discovered a romantic letter or message written in the sand, you don’t have to experiment to know that it was by design and not because a stick randomly carried by wind put it there. You naturally assume that an intelligent and rational being was responsible.

    It’s interesting that Carl Sagan would have acknowledged sequential radio signals in space as evidence of intelligent life sending them, but he wouldn’t acknowledge the sequential structure of molecules in DNA (the genetic code) as evidence of an intelligent Cause. Read my popular Internet article, HOW DID MY DNA MAKE ME.

    I encourage all to read my popular Internet articles:


    Visit my latest Internet site: THE SCIENCE SUPPORTING CREATION (This site answers many arguments, both old and new, that have been used by evolutionists to support their theory)


    *I have given successful lectures (with question and answer period afterwards) defending creation before evolutionist science faculty and students at various colleges and universities. I’ve been privileged to be recognized in the 24th edition of Marquis “Who’s Who in The East” for my writings on religion and science.

  5. Sekar, the atomic mass shown in the tables is the average mass for a specimen considering the relative abundance of all(?) isotopes, hence the decimals.

  6. ¥€π×π×|~> | February 16, 2022 at 11:08 pm | Reply

    We did come from another origin, another spiceies, from far away from here,thousands of years ago we were put here as two different tribes, to see which one would make it, the wrong one did. Now they don’t know for sure what to do about it, but have about decided now, we will know before to long, and know what’s out there to.

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