FILE – In this Nov. 29, 2006 file photo workers stand in front of a big spectrometer which is the heart of the tritium-neutrino- experiment at the research center of Karlruhe in Eggenstein-Leopoldshafen. (AP Photo/Winfried Rothermel, file)
ASSOCIATED PRESS
Addressed to “Dear radioactive ladies and gentlemen,” Pauli’s letter contained a radical proposal regarding the vexing problem of beta decay of nuclei. Atomic nuclei can decay in three principal ways, which were tagged with the first three letters of the Greek alphabet by Ernest Rutherford around1900 Alpha particles, primarily emitted by extremely heavy nuclei, are helium-4 nuclei (two protons and two neutrons tightly bound together); beta particles, emitted by unstable elements all across the periodic table, are electrons; and gamma radiation, beloved by comic-book authors of the 1950’s, is just high-frequency light. In two of these, the emission process proceeds in a sensible way– both alpha particles and gamma rays are emitted with very specific energies that are characteristic of the element that’s falling apart. Beta particles, on the other hand, are emitted over a wide range of energies, up to some maximum value.
Beta-minus Decay
Getty
This was confounding to physicists in 1930, because it seems to defy the laws of conservation of energy and momentum. The single energy peak seen in alpha decay makes sense as the escape of a particle that existed inside the nucleus at a well-defined energy as required by quantum physics, but for the same element to be spitting out beta particles with very different energies just doesn’t fit with what was known about the principles of physics. Some of the more radical thinkers at the time– notably Niels Bohr– were prepared to demote energy conservation from a fundamental law to only a statistical regularity, but most physicists were uneasy about this.
Pauli’s letter contained a bold suggestion that both explained the beta-decay spectrum and saved the idea of energy conservation. The wide energy spread of the beta particles from nuclear decay would make sense, he argued, if there was a third particle involved in addition to the electron and the nucleus from whence it came. That third particle, undetected to that point in physics, carries off a bunch of energy that also varies over a wide range, and the sum of the energies of this particle, the electron emitted, and the nucleus recoiling away from both of these (in keeping with momentum conservation) add up to a single, sensible value.
Pauli’s ghost particle can’t have any electric charge, so he proposed calling it the “neutron,” but Enrico Fermi later christened it the “neutrino” to distinguish it from the heavy neutron that accounts for much of the mass of the nucleus (discovered by James Chadwick in 1932). Pauli himself was uneasy about the idea of an undetectable particle– he self-deprecatingly called it “something no theorist should ever do– which is why he sent it in an informal letter rather than as a formal paper. The idea caught on quickly, though, particularly with Fermi, who worked out a complete theory of nuclear decays including the neutrino within a few years of the Tübingen meeting.
Dr. Enrico Fermi, leader of the group of scientists who succeeded in initiating the first man-made nuclear chain reaction is picture in an undated photo. (AP Photo)
ASSOCIATED PRESS
Of course, the idea of an undetectable particle is the kind of thing that will nag at physicists, particularly experimentalists, and people immediately started poking at the theory of Pauli and Fermi to see if there might be a way to detect these things. This is a tricky problem, because neutrinos interact exceptionally weakly with the rest of the known particles, but Hans Bethe and Rudolf Peierls noted that the inverse of beta decay ought to theoretically be possible– that is, a nucleus absorbing both a neutrino and an electron. The probability of this happening is exceedingly small, though, and Peierls and Bethe calculated that a neutrino should easily be able to pass through the entire Earth without interacting with anything.
“Exceedingly unlikely” is very different than “impossible,” though, and given enough neutrinos and a good-sized detector, it ought to be possible to detect them. And, indeed, the neutrino was detected using inverse beta decay, by Clyde Cowan and Frederick Reines in1956 Their detector used about 200 liters of water with cadmium salts dissolved in it, sandwiched between layers of gamma-ray detectors, and to get a detectable flux of neutrinos they placed it next to a nuclear reactor in South Carolina. (Their first idea was to put it close to an atomic bomb test, which would’ve greatly increased the challenges of collecting the data…) Their detector picked up only a few particles an hour, but it was enough to confirm the existence of the neutrino– Pauli happily bought Walter Baade a case of champagne to settle his bet that the discovery would never happen, and Reines was eventually awarded a share of the 1995 Nobel Prize (Cowan had died in 1974, and the Nobel is not awarded posthumously).
Neutrino physics has come a long way since those days, with Ray Davis and Masatoshi Koshiba sharing the 2002 Nobel Prize in Physics for building better neutrino detectors. In Davis’s case, this was a 600-ton tank of industrial cleaning fluid in a mine, and every few months he would chemically separate a handful of argon atoms created when a neutrino was absorbed by a chlorine atom in the tank. Koshiba’s detector, the Kamiokande neutrino observatory, was even bigger– around 50,000 tons of water– but read out in real time, as neutrinos striking nuclei in the water produced small flashes of light picked up by phototubes surrounding the water tank.
A decade later, Takaaki Kajita and Art McDonald shared the 2015 Nobel Prize in Physics for using the Kamiokande detector and a similar experiment in Sudbury, Ontario to show that neutrinos, which come in three different “flavors,” oscillate between those flavors. This last discovery was particularly momentous, as it implies that neutrinos must have mass.
Pauli’s original proposal is agnostic on the question of neutrino mass– he says only that it must be smaller than that of the electron, then the lightest known particle– but as the Standard Model of particle physics came together, the simplest arrangement of everything would give the neutrino exactly zero mass. The definitive detection of neutrino oscillations by Kajita and McDonald (and the huge experimental collaborations they headed) rules out that possibility, though, which makes the neutrino one of the most concrete examples of “new physics” that we have: a well-documented physical phenomenon that can’t be explained from within the Standard Model framework.
That “new physics” aspect makes neutrino physics a hot topic, which is why it was prominently featured in a plenary session at the APS April Meeting earlier this month (see also this Physics World story). As is always the case with “new physics,” there are a lot of possibilities (spelled out nicely if somewhat math-ily in the plenary talk by André de Gouvêa at that link), and lots of ideas for experiments to sort these out (ably surveyed by Susanne Mertens in the Kavli symposium).
The 200-ton central part of the KATRIN detector making its way to Karlsruhe.
MICHAEL LATZ/AFP/Getty Images
Maybe my favorite of these experimental proposals is the Karlsruhe Tritium Neutrino (KATRIN) experiment, because it’s a beautiful combination of simple concept and incredibly difficult execution. The central idea of the experiment is something that would’ve been instantly comprehensible to Pauli and his radioactive colleagues at the Tübingen meeting: they don’t measure the neutrino directly, but simply measure the properties of the electron to look for an energy shift due to the neutrino’s mass.
If the neutrino were truly massless, the energy of the beta-decay electrons would extend all the way up to the maximum possible value for the decay of that nucleus, corresponding to the emission of a massless neutrino with essentially zero kinetic energy. A neutrino with mass, though, will push the maximum energy of an emitted electron down a tiny bit– no matter how little kinetic energy you give the neutrino, it must have a tiny amount of rest energy due to its mass. That lowers the maximum energy of the electron, and changes the shape of the spectrum at those high energies in an easily predictable manner.
Actually doing that measurement is incredibly difficult, though. The neutrino mass is tiny– as de Gouvêa noted, if you make an analogy between particles and animals, making the heaviest known particle a blue whale, electrons are bunny rabbits, and neutrinos are fruit flies (“they’re not even mammals”). To attain the necessary precision, the KATRIN detector is gigantic– larger than the houses in the town they needed to move it through to reach the lab. The maximum-energy electrons they’re after represent a tiny fraction of the total, too, meaning they need an enormous amount of tritium (the lightest nucleus that beta decays, which maximizes the energy shift they hope to observe) and a long period of data collection.
(KATRIN isn’t the only experiment pursuing this angle, for the record: there’s also the Project 8 experiment, which has a very different detection scheme as well as a name that isn’t a strained acronym. KATRIN is a little farther along, though, and more photogenic.)
In a field where Cowan and Reines were willing to consider parking their detector next to an atomic bomb, though, this level of effort and ingenuity fits right in. And while these experiments are huge and expensive, the payoff is well worth it, given the neutrino mass is the one sure thing we have when it comes to testing physics beyond the Standard Model.
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In December, 1930, a group of physicists assembled a conference in Tübingen, Germany to go over the most recent advancements in nuclear physics. A sensible individual to have at such a conference would’ve been Wolfgang Pauli, the notoriously acerbic young Austrian physicist who had actually currently made critical contributions to the emerging field of quantum mechanics. Pauli, however, had social responsibilities in Zurich, so he sent out a letter in his stead, which ends up being among the most crucial letters in the history of physics.
FILE -In this Nov.(****************************************************************************** ),(************************************************ )file picture employees stand in front of a huge spectrometer which is the heart of the tritium-neutrino- experiment at the proving ground of Karlruhe in Eggenstein-Leopoldshafen. (AP Photo/Winfried Rothermel, file)
ASSOCIATED PRESS
Dealt With to “Dear radioactive girls and gentlemen,” Pauli’s letter consisted of an extreme proposition relating to the vexing issue of beta decay of nuclei. Atomic nuclei can decay in 3 primary methods, which were tagged with the very first 3 letters of the Greek alphabet by Ernest Rutherford around1900 Alpha particles, mainly discharged by very heavy nuclei, are helium-4 nuclei (2 protons and 2 neutrons securely bound together); beta particles, discharged by unsteady aspects all throughout the table of elements, are electrons; and gamma radiation, precious by comic-book authors of the 1950’s, is simply high-frequency light. In 2 of these, the emission procedure profits in a reasonable method– both alpha particles and gamma rays are discharged with extremely particular energies that are particular of the aspect that’s breaking down. Beta particles, on the other hand, are discharged over a wide variety of energies, as much as some optimum worth.
Getty
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This was confusing to physicists in1930, due to the fact that it appears to defy the laws of preservation of energy and momentum. The single energy peak seen in alpha decay makes good sense as the escape of a particle that existed inside the nucleus at a distinct energy as needed by quantum physics, however for the exact same aspect to be spitting out beta particles with extremely various energies simply does not fit with what was learnt about the concepts of physics. A few of the more extreme thinkers at the time– significantly Niels Bohr– were prepared to bench energy preservation from an essential law to just an analytical consistency, however many physicists were anxious about this.
Pauli’s letter consisted of a vibrant idea that both described the beta-decay spectrum and conserved the concept of energy preservation. The large energy spread of the beta particles from nuclear decay would make good sense, he argued, if there was a 3rd particle associated with addition to the electron and the nucleus from whence it came. That 3rd particle, unnoticed to that point in physics, brings off a lot of energy that likewise differs over a wide variety, and the amount of the energies of this particle, the electron released, and the nucleus recoiling far from both of these (in keeping with momentum preservation) amount to a single, practical worth.
Pauli’s ghost particle can’t have any electrical charge, so he proposed calling it the “neutron,” however Enrico Fermi later on christened it the “neutrino” to differentiate it from the heavy neutron that represents much of the mass of the nucleus (found by James Chadwick in 1932). Pauli himself was anxious about the concept of an undetected particle– he self-deprecatingly called it “something no theorist must ever do– which is why he sent it in a casual letter instead of as an official paper. The concept captured on rapidly, however, especially with Fermi, who exercised a total theory of nuclear decays consisting of the neutrino within a couple of years of the Tübingen conference.
Dr. Enrico Fermi, leader of the group of researchers who prospered in starting the very first manufactured nuclear domino effect is photo in an undated picture. (AP Image)
ASSOCIATED PRESS
Naturally, the concept of an undetected particle is the example that will scold at physicists, especially experimentalists, and individuals instantly began poking at the theory of Pauli and Fermi to see if there may be a method to identify these things. This is a difficult issue, due to the fact that neutrinos engage extremely weakly with the remainder of the recognized particles, however Hans Bethe and Rudolf Peierls kept in mind that the inverse of beta decay should in theory be possible– that is, a nucleus soaking up both a neutrino and an electron. The likelihood of this taking place is extremely little, however, and Peierls and Bethe computed that a neutrino needs to quickly have the ability to travel through the whole Earth without connecting with anything.
” Exceptionally not likely” is extremely various than “difficult,” though, and offered enough neutrinos and a good-sized detector, it should be possible to identify them. And, undoubtedly, the neutrino was discovered utilizing inverted beta decay, by Clyde Cowan and Frederick Reines in1956 Their detector utilized about 200 liters of water with cadmium salts liquified in it, sandwiched in between layers of gamma-ray detectors, and to get a noticeable flux of neutrinos they put it beside an atomic power plant in South Carolina. (Their very first concept was to put it near an atomic bomb test, which would’ve considerably increased the difficulties of gathering the information …) Their detector got just a few particles an hour, however it sufficed to verify the presence of the neutrino– Pauli gladly purchased Walter Baade a case of champagne to settle his bet that the discovery would never ever take place, and Reines was ultimately granted a share of the 1995 Nobel Reward(Cowan had actually passed away in 1974, and the Nobel is not granted posthumously).
Neutrino physics has actually come a long method because those days, with Ray Davis and Masatoshi Koshiba sharing the 2002 Nobel Reward in Physics for constructing much better neutrino detectors. In Davis’s case, this was a 600- heap tank of commercial cleansing fluid in a mine, and every couple of months he would chemically separate a handful of argon atoms developed when a neutrino was soaked up by a chlorine atom in the tank. Koshiba’s detector, the Kamiokande neutrino observatory, was even larger– around 50,000 lots of water– however read out in genuine time, as neutrinos striking nuclei in the water produced little flashes of light gotten by phototubes surrounding the water tank.
A years later on, Takaaki Kajita and Art McDonald shared the 2015 Nobel Reward in Physics for utilizing the Kamiokande detector and a comparable experiment in Sudbury, Ontario to reveal that neutrinos, which can be found in 3 various “tastes,” oscillate in between those tastes. This last discovery was especially special, as it indicates that neutrinos need to have mass.
Pauli’s initial proposition is agnostic on the concern of neutrino mass– he states just that it should be smaller sized than that of the electron, then the lightest recognized particle– however as the Requirement Design of particle physics came together, the most basic plan of whatever would offer the neutrino precisely no mass. The conclusive detection of neutrino oscillations by Kajita and McDonald (and the substantial speculative partnerships they headed) eliminate that possibility, however, that makes the neutrino among the most concrete examples of “brand-new physics” that we have: a well-documented physical phenomenon that can’t be described from within the Requirement Design structure.
That “brand-new physics” element makes neutrino physics a hot subject, which is why it was plainly included in a plenary session at the APS April Fulfilling previously this month (see likewise this Physics World story). As is constantly the case with “brand-new physics,” there are a great deal of possibilities (defined perfectly if rather math-ily in the plenary talk by André de Gouvêa at that link), and great deals of concepts for experiments to arrange these out (capably surveyed by Susanne Mertens in the Kavli seminar).
The200- heap main part of the KATRIN detector making its method to Karlsruhe.
MICHAEL LATZ/AFP/Getty Images
Perhaps my favorite of
these speculative propositions is the Karlsruhe Tritium Neutrino( KATRIN) experiment , due to the fact that it’s a gorgeous mix of basic idea and extremely challenging execution. The main concept of the experiment is something that would’ve been immediately understandable to Pauli and his radioactive associates at the Tübingen conference: they do not determine the neutrino straight, however merely determine the residential or commercial properties of the electron to try to find an energy shift due to the neutrino’s mass.
If the neutrino were genuinely massless, the energy of the beta-decay electrons would
extend all the method as much as the optimum possible worth for the decay of that nucleus, representing the emission of a massless neutrino with basically no kinetic energy. A neutrino with mass, however, will press the optimum energy of a produced electron down a little bit– no matter how little kinetic energy you offer the neutrino, it(***************** )should have a small quantity of rest energy due to its mass. That decreases the optimum energy of the electron, and alters the shape of the spectrum at those high energies in a quickly foreseeable way.(**** )
Really(***************** )doing that measurement is extremely challenging, though.
The neutrino mass is small– as de Gouvêa kept in mind, if you make an example in between particles and animals, making the heaviest recognized particle a blue whale, electrons are bunny rabbits, and neutrinos are fruit flies(” they’re not even mammals”). To achieve the needed accuracy, the KATRIN detector is enormous– bigger than your homes in the town they required to move it through to reach the laboratory. The maximum-energy electrons they want represent a small portion of the overall, too, implying they require a huge quantity of tritium( the lightest nucleus that beta decomposes, which takes full advantage of the energy shift they intend to observe) and an extended period of information collection.
( KATRIN isn’t the only experiment pursuing this angle, for the record: there’s likewise the Task 8 experiment, which has an extremely various detection plan along with a name that isn’t a stretched acronym. KATRIN is a little further along, though, and more photogenic.)
(* )In a field where Cowan and Reines wanted to think about parking their detector beside an atomic bomb, however, this level of effort and resourcefulness fits right in. And while these experiments are substantial and costly, the benefit is well worth it, offered the neutrino mass is the one safe bet we have when it concerns screening physics beyond the Requirement Design.
” readability =” 180.28032345013″ >
In December,1930, a group of physicists assembled a conference in Tübingen, Germany to go over the most recent advancements in nuclear physics. A sensible individual to have at such a conference would’ve been Wolfgang Pauli, the notoriously acerbic young Austrian physicist who had actually currently made critical contributions to the emerging field of quantum mechanics. Pauli, however, had social responsibilities in Zurich, so he(** )sent out a letter in his stead, which ends up being among the most crucial letters in the history of physics.
FILE – In this Nov. 29, 2006 file picture employees stand in front of a huge spectrometer which is the heart of the tritium-neutrino – experiment at the proving ground of Karlruhe in Eggenstein-Leopoldshafen. (AP Photo/Winfried Rothermel, file)
ASSOCIATED PRESS
.
.
Dealt With to “Dear radioactive girls and gentlemen,” Pauli’s letter consisted of an extreme proposition relating to the vexing issue of beta decay of nuclei. Atomic nuclei can decay in 3 primary methods, which were tagged with the very first 3 letters of the Greek alphabet by Ernest Rutherford around1900 Alpha particles, mainly discharged by very heavy nuclei, are helium-4 nuclei (2 protons and 2 neutrons securely bound together); beta particles, discharged by unsteady aspects all throughout the table of elements, are electrons; and gamma radiation, precious by comic-book authors of the 1950’s, is simply high-frequency light. In 2 of these, the emission procedure profits in a reasonable method– both alpha particles and gamma rays are discharged with extremely particular energies that are particular of the aspect that’s breaking down. Beta particles, on the other hand, are discharged over a wide variety of energies, as much as some optimum worth.
This was confusing to physicists in 1930, due to the fact that it appears to defy the laws of preservation of energy and momentum. The single energy peak seen in alpha decay makes good sense as the escape of a particle that existed inside the nucleus at a distinct energy as needed by quantum physics, however for the exact same aspect to be spitting out beta particles with extremely various energies simply does not fit with what was learnt about the concepts of physics. A few of the more extreme thinkers at the time– significantly Niels Bohr– were prepared to bench energy preservation from an essential law to just an analytical consistency, however many physicists were anxious about this.
Pauli’s letter consisted of a vibrant idea that both described the beta-decay spectrum and conserved the concept of energy preservation. The large energy spread of the beta particles from nuclear decay would make good sense, he argued, if there was a 3rd particle associated with addition to the electron and the nucleus from whence it came. That 3rd particle, unnoticed to that point in physics, brings off a lot of energy that likewise differs over a wide variety, and the amount of the energies of this particle, the electron released, and the nucleus recoiling far from both of these (in keeping with momentum preservation) amount to a single, practical worth.
Pauli’s ghost particle can’t have any electrical charge, so he proposed calling it the “neutron,” however Enrico Fermi later on christened it the “neutrino” to differentiate it from the heavy neutron that represents much of the mass of the nucleus (found by James Chadwick in 1932). Pauli himself was anxious about the concept of an undetected particle– he self-deprecatingly called it “something no theorist must ever do– which is why he sent it in a casual letter instead of as an official paper. The concept captured on rapidly, however, especially with Fermi, who exercised a total theory of nuclear decays consisting of the neutrino within a couple of years of the Tübingen conference.
Dr. Enrico Fermi, leader of the group of researchers who prospered in starting the very first manufactured nuclear domino effect is photo in an undated picture. (AP Image)
ASSOCIATED PRESS
.
.
Naturally, the concept of an undetected particle is the example that will scold at physicists, especially experimentalists, and individuals instantly began poking at the theory of Pauli and Fermi to see if there may be a method to identify these things. This is a difficult issue, due to the fact that neutrinos engage extremely weakly with the remainder of the recognized particles, however Hans Bethe and Rudolf Peierls kept in mind that the inverse of beta decay should in theory be possible– that is, a nucleus soaking up both a neutrino and an electron. The likelihood of this taking place is extremely little, however, and Peierls and Bethe computed that a neutrino needs to quickly have the ability to travel through the whole Earth without connecting with anything.
“Exceptionally not likely” is extremely various than “difficult,” though, and offered enough neutrinos and a good-sized detector, it should be possible to identify them. And, undoubtedly, the neutrino was discovered utilizing inverted beta decay, by Clyde Cowan and Frederick Reines in1956 Their detector utilized about 200 liters of water with cadmium salts liquified in it, sandwiched in between layers of gamma-ray detectors, and to get a noticeable flux of neutrinos they put it beside an atomic power plant in South Carolina. (Their very first concept was to put it near an atomic bomb test, which would’ve considerably increased the difficulties of gathering the information …) Their detector got just a few particles an hour, however it sufficed to verify the presence of the neutrino– Pauli gladly purchased Walter Baade a case of champagne to settle his bet that the discovery would never ever take place, and Reines was ultimately granted a share of the 1995 Nobel Reward (Cowan had actually passed away in 1974, and the Nobel is not granted posthumously).
Neutrino physics has actually come a long method because those days, with Ray Davis and Masatoshi Koshiba sharing the 2002 Nobel Reward in Physics for constructing much better neutrino detectors. In Davis’s case, this was a 600 – heap tank of commercial cleansing fluid in a mine, and every couple of months he would chemically separate a handful of argon atoms developed when a neutrino was soaked up by a chlorine atom in the tank. Koshiba’s detector, the Kamiokande neutrino observatory, was even larger– around 50, 000 lots of water– however read out in genuine time, as neutrinos striking nuclei in the water produced little flashes of light gotten by phototubes surrounding the water tank.
A years later on, Takaaki Kajita and Art McDonald shared the 2015 Nobel Reward in Physics for utilizing the Kamiokande detector and a comparable experiment in Sudbury, Ontario to reveal that neutrinos, which can be found in 3 various “tastes,” oscillate in between those tastes. This last discovery was especially special, as it indicates that neutrinos need to have mass.
Pauli’s initial proposition is agnostic on the concern of neutrino mass– he states just that it should be smaller sized than that of the electron, then the lightest recognized particle– however as the Requirement Design of particle physics came together, the most basic plan of whatever would offer the neutrino precisely no mass. The conclusive detection of neutrino oscillations by Kajita and McDonald (and the substantial speculative partnerships they headed) eliminate that possibility, however, that makes the neutrino among the most concrete examples of “brand-new physics” that we have: a well-documented physical phenomenon that can’t be described from within the Requirement Design structure.
That “brand-new physics” element makes neutrino physics a hot subject, which is why it was plainly included in a plenary session at the APS April Fulfilling previously this month (see likewise this Physics World story ). As is constantly the case with “brand-new physics,” there are a great deal of possibilities (defined perfectly if rather math-ily in the plenary talk by André de Gouvêa at that link), and great deals of concepts for experiments to arrange these out (capably surveyed by Susanne Mertens in the Kavli seminar).
The 200 – heap main part of the KATRIN detector making its method to Karlsruhe.
MICHAEL LATZ/AFP/Getty Images
.
.
Perhaps my favorite of these speculative propositions is the Karlsruhe Tritium Neutrino (KATRIN) experiment , due to the fact that it’s a gorgeous mix of basic idea and extremely challenging execution. The main concept of the experiment is something that would’ve been immediately understandable to Pauli and his radioactive associates at the Tübingen conference: they do not determine the neutrino straight, however merely determine the residential or commercial properties of the electron to try to find an energy shift due to the neutrino’s mass.
If the neutrino were genuinely massless, the energy of the beta-decay electrons would extend all the method as much as the optimum possible worth for the decay of that nucleus, representing the emission of a massless neutrino with basically no kinetic energy. A neutrino with mass, however, will press the optimum energy of a produced electron down a little bit– no matter how little kinetic energy you offer the neutrino, it should have a small quantity of rest energy due to its mass. That decreases the optimum energy of the electron, and alters the shape of the spectrum at those high energies in a quickly foreseeable way.
Really doing that measurement is extremely challenging, though. The neutrino mass is small– as de Gouvêa kept in mind, if you make an example in between particles and animals, making the heaviest recognized particle a blue whale, electrons are bunny rabbits, and neutrinos are fruit flies (” they’re not even mammals”). To achieve the needed accuracy, the KATRIN detector is enormous– bigger than your homes in the town they required to move it through to reach the laboratory. The maximum-energy electrons they want represent a small portion of the overall, too, implying they require a huge quantity of tritium (the lightest nucleus that beta decomposes, which takes full advantage of the energy shift they intend to observe) and an extended period of information collection.
(KATRIN isn’t the only experiment pursuing this angle, for the record: there’s likewise the Task 8 experiment, which has an extremely various detection plan along with a name that isn’t a stretched acronym. KATRIN is a little further along, though, and more photogenic.)
In a field where Cowan and Reines wanted to think about parking their detector beside an atomic bomb, however, this level of effort and resourcefulness fits right in. And while these experiments are substantial and costly, the benefit is well worth it, offered the neutrino mass is the one safe bet we have when it concerns screening physics beyond the Requirement Design.
.
