Neutrinomax
Columbia physicist and neutrino hunter Professor Georgia Karagiorgi explains:
If
A
Fourth
Neutrino
Type
Exists
16 Sep 2021
On 08 September 2021 the news in the website of the Columbia University "news.columbia.edu" published a report entitled "Searching for Ghostly Neutrinos to Understand Why Matter Dominates the Universe" written by Kim Martineau.
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
Kim Martineau writes:
"What's a neutrino and how do you detect one? Columbia physicist and neutrino hunter Georgia Karagiorgi explains, and describes what she hopes to learn at the Fermilab accelerator near Chicago."
The author quotes
Georgia Karagiorgi, an associate physics professor at Columbia as saying:
"Subatomic particles may sound mysterious, but they’re an essential, even beautiful, part of our world."
Professor Karagiorgi addresses:
“Everything is made of particles.”
She explains:
"If it wasn’t for them, we wouldn’t be here."
Professor Karagiorgi points out:
"They provide us with a simple and elegant prescription—a set of building blocks and rules—from which we can derive everything around us.”
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
K. Martineau writes:
"With Columbia professor
Michael Shaevitz, Karagiorgi is part of a long-running hunt for new types of neutrinos at Fermilab, a national particle accelerator laboratory near Chicago."
The author explains:
"Neutrinos are elementary particles created naturally, by nuclear reactions in stars like our Sun, or artificially, in nuclear reactors and particle accelerators."
The writer states:
"Neutrinos are similar to electrons, but with hardly any mass and no electrical charge."
K. Martineau writes:
"In the last two decades, physicists have established that neutrinos can flip, or oscillate, between three known weakly interacting states—muon-neutrino, tau-neutrino, and electron-neutrino."
The author points out:
"Hints of a fourth neutrino-type have been found in previous neutrino experiments at Fermilab and Los Alamos National Lab, and Karagiorgi and Shaevitz are now seeking to confirm or refute its existence."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
K. Martineau writes:
"One thing is for sure: if a fourth neutrino-type exists, it wouldn’t interact with matter in the same way as its three known relatives, said Karagiorgi."
The author writes:
"Confirmation of a so-called sterile neutrino would challenge the “Standard Model” of particle physics, which has held for the last 60 years."
The writer explains:
"Results from Fermilab’s MicroBooNE experiment is expected to shed more light on the mystery."
The author states:
"Meanwhile, Fermilab is set to launch a related, more sensitive search for sterile neutrinos,
the Short- Baseline Neutrino Program.
K. Martineau writes:
"Karagiorgi and Shaevitz are involved in that experiment, too."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
Q: What’s the Standard Model of particle physics and where do neutrinos fit in?
Georgia Karagiorgi:
"Like the periodic table in chemistry, it’s a catalog of all known fundamental particles that make up matter."
She addresses:
"Particles are organized by their properties—like intrinsic spin, mass, and electric charge—which allows us to understand their underlying dynamics and how they interact with each other."
G. Karagiorgi points out:
"Since the 1960s, this theoretical framework has been amazingly predictive."
She adds:
"It has withstood the test of hundreds of experiments and measurements."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
G. Karagiorgi states:
"However, it can’t explain our observations of dark matter in space or neutrinos morphing from one state to another."
Prof. Karagiori addresses:
"If neutrinos have no mass, as the Standard Model prescribes, they shouldn’t be able to oscillate."
The writer explains:
"An extension to the Standard Model now accommodates neutrino oscillation, but sterile neutrinos would be one more challenge."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
Q. You can’t directly observe neutrinos. So how do you isolate and study them?
Prof. Karagiorgi:
"Neutrinos traverse our detectors without leaving a trail, but every now and then they collide head-on with an atomic nucleus."
She explains:
The explosion that follows usually produces a spray of charged particles—electrons, muons, and/or protons."
Professor Karagiorgi points out:
"Each charged particle leaves behind a trail of scintillation light and ionization electrons produced by excited atoms along the charged particle's path."
She explains:
"By detecting those trails, we can usually infer the presence of a neutrino, its identity, and how fast and in what direction it’s traveling."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
Scientists Detect
Neutrinos
From Sun’s Core
G. Bellini et al.
Aug 31, 2014
Sci-News.com
A multinational collaboration of physicists has directly detected neutrinos created by the proton-proton fusion process going on at the heart of the Sun.[1]
Physicists have directly detected pp neutrinos, demonstrating that about 99 per cent of the power of the Sun is generated by the pp fusion process.[1]
In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium.[1]
The primary reaction is thought to be the proton-proton (pp) fusion with the emission of a low-energy neutrino.[1]
These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux and stream out of the Sun at nearly the speed of light.[1]
Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from pp fusion have eluded direct detection for decades.[1]
David W. Casper
The School of Physical Sciences
The University of California, Irvine
Neutrinos are one of the fundamental particles which make up the universe. They are also one of the least understood.[2]
Neutrinos are similar to the more familiar electron, with one crucial difference: neutrinos do not carry electric charge. [2]
1931 - A hypothetical particle is predicted by the theorist Wolfgang Pauli.[2]
Pauli based his prediction on the fact that energy and momentum did not appear to be conserved in certain radioactive decays.[2]
Pauli suggested that this missing energy might be carried off, unseen, by a neutral particle which was escaping detection.[2]
Because neutrinos are electrically neutral, they are not affected by the electromagnetic forces which act on electrons.[2]
Neutrinos are affected only by a "weak" sub-atomic force of much shorter range than electromagnetism, and are therefore able to pass through great distances in matter without being affected by it.[2]
If neutrinos have mass, they also interact gravitationally with other massive particles, but gravity is by far the weakest of the four known forces.[2]
Three types of neutrinos are known; there is strong evidence that no additional neutrinos exist, unless their properties are unexpectedly very different from the known types. [2]
Each type or "flavor" of neutrino is related to a charged particle (which gives the corresponding neutrino its name). [2]
Hence, the "electron neutrino" is associated with the electron, and two other neutrinos are associated with heavier versions of the electron called the muon and the tau (elementary particles are frequently labelled with Greek letters, to confuse the layman). [2]
1989 - Kamiokande becomes the second experiment to detect neutrinos from the Sun, and confirms the long-standing anomaly by finding only about 1/3 the expected rate.[2]
1997 - Super-Kamiokande reports a deficit of cosmic-ray muon neutrinos and solar electron neutrinos, at rates agreeing with measurements by earlier experiments. [2]
1998 - The Super-Kamiokande collaboration announces evidence of non-zero neutrino mass at the Neutrino '98 conference.[2]
My research is focused on the most fundamental known constituents and forces of nature. [2]
The goal of elementary particle physics is to unify, if possible, the laws of nature into a single consistent, economical description.[3]
One area of recent excitement concerns neutrinos - electrically neutral versions of the more familiar electron, which are able to pass through enormous amounts of matter without interacting.[3]
With the Super-Kamiokande experiment in Japan, my colleagues and I have shown that these ghostly particles, long-believed to be perfectly massless, not only carry mass but change their very character ("oscillate") as they whiz through space.[3]
In a related experiment called K2K, we have shot a man-made beam of neutrinos through the earth, to a detector 250 km away, further confirming the original discovery.[3]
A second-generation experiment, T2K, will measure the mixing between neutrinos, and their masses, more precisely, and hopefully discover a new and predicted mode of oscillation. [3]
By understanding what makes neutrinos oscillate, we hope to uncover new evidence for the "theory of everything", and may explain why the universe consists almost entirely of matter, rather than anti-matter.[3]
nature
.com|
David
Castelvecchi|
16
July
2021:
The
vanishing
neutrinos
that
could
upend
fundamental
physics
Neutrino Birth:
Wolfgang Pauli
4 December 1930
Neutrino Mysteries, Surprises and Promises
Carlo Giunti
Organiser:
Francesca Di Lodovico
INFN, Sezione di Torino
&
Dipartimento di Fisica Teorica
Universit`a di Torino
ESOF, Torino
4 July 2010
4 December 1930: Wolfgang Pauli sent a Public letter to the group of the Radioactives at the district society meeting in Tueubingen
Dear Radioactive Ladies and Gentlemen
. . . I have hit upon a desperate remedy to save . . . the law of
conservation of energy. Namely, the possibility that there could exist in the nuclei electrically neutral particles, that I wish to call neutrons . . .The continuous -spectrum would then become understandable by the assumption that in -decay, a neutron is emitted in addition to the electron such that the sum of the
energies of the neutron and electron is constant.[4]
1933: Enrico Fermi proposes the name neutrino (italian: small neutron) at the Solvay Congress in Brussels.1934: Enrico Fermi formulates A Theory of Beta Radiation which is the theory of Weak Interactions. Neutrinos interact only with Weak Interactions =)Very difficult to detect (maybe impossible; H. Bethe and R. Peierls, 1934).[4]
The neutrino mass much be much smaller than the electron mass. Maybe the neutrino is massless. Fermi received the 1938 Physics Nobel Prize “for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons.”[4]
From what we know today, a majority of the neutrinos floating around were born around 15 billions years ago, soon after the birth of the universe.The neutrino was first postulated in December, 1930 by Wolfgang Pauli to explain the energy spectrum of beta decays, the decay of a neutron into a proton and an electron.[5]
Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed.[5]
In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science, a result that was rewarded with the 1995 Nobel Prize. [5]
Ice Cube
sees
Highest-Energy Neutrino Ever Found
Kathryn Jepsen
August 04, 2015
In 2013, the IceCube neutrino experiment at the South Pole reported the observation of two ultra-high-energy neutrino events, which they named after Sesame Street characters Bert and Ernie. Later, they found one more.[6]
Today IceCube scientists reported the observation of an even higher-energy neutrino event, one that offers scientists the best hope yet that they will be able to use ultra-high-energy neutrinos to find the source of ultra-high-energy cosmic rays. The neutrino event had an energy of more than 2000 trillion electronvolts.[6]
For more than a century, scientists have known that particles called cosmic rays rain down on the Earth from space. Some of these cosmic rays slam into our atmosphere at energies higher than we could possibly reach in any earthly particle accelerator.[6]
It is still a mystery where these particles come from, but it seems that they are from energetic sources outside our galaxy. One suspicion is that they are coming from active galaxies swirling around distant black holes.[6]
Cosmic rays are charged particles, which means that their paths bend and shift as they pass through magnetic fields in space. That makes it difficult to trace their origins.[6]
That’s where neutrinos come in. Neutrinos are neutral, rarely interacting particles that can pass through entire planets without changing course.[6]
Ultra-high-energy neutrinos that the IceCube experiment observes could be coming from the same sources as ultra-high-energy cosmic rays. If so, they could point the way back to those sources.[6]
“This opens the neutrino astronomy field,” says Fermilab neutrino scientist Anne Schukraft, a former member of the IceCube collaboration.Neutrinos come in three types, called flavors: electron, muon and tau. [6]
When electron and tau neutrinos interact with the ice around the IceCube neutrino detector, their energy appears to balloon out from their interaction points, making it difficult to figure out exactly where they came from.[6]
Cosmic Neutrinos Confirmed at South Pole
EarthSky
Human World, Science Wire, Space
Aug 25, 2015
Researchers say these high-energy neutrinos come from sources beyond our Milky Way galaxy. They say the ability to discover them heralds a new form of astronomy.[7]
Researchers at the South Pole – using a cubic-kilometer particle detector embedded in Antarctic ice – say they have provided independent confirmation of a 2013 sighting of cosmic neutrinos. [7]
These ultra high-energy particles are thought to have traversed space unimpeded by stars, planets, galaxies, magnetic fields or clouds of interstellar dust before their detection by the IceCube Neutrino Observatory at the South Pole.[7]
Did this telescope actually detect the neutrinos? No. It detected secondary particles – called muons – created on the rare occasions when neutrinos interact with matter. Still, it’s a formidable piece of research, published on August 20, 2015 in the journal Physical Review Letters. [7]
There are some mightily cool aspects of this far-southern study. The telescope at the South Pole, for example, is unlike any other on Earth.[7]
The IceCube Neutrino Observatory is composed of thousands of optical sensors sunk deep beneath Antarctic ice. [7]
It’s designed to look through the Earth to observe the Northern Hemisphere sky. In this way, Earth acts as a filter to help weed out a confusing background of muons created when cosmic rays crash into the Earth’s atmosphere. [7]
Francis Halzen, a University of Wisconsin, Madison, professor of physics and the principal investigator of IceCube, said:Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy, and it has delivered. [7]
This is as close to independent confirmation as one can get with a unique instrument.[7]
[1]http://www.sci-news.com/physics/science-neutrinos-suns-core-02125.html
[2]http://www.ps.uci.edu/~superk/neutrino.html
[3]http://www.faculty.uci.edu/profile.cfm?faculty_id=4796
[4]http://www.nu.to.infn.it/slides/2010/giunti-100704-esof.pdf
[5]https://icecube.wisc.edu/info/neutrinos
[6]http://www.symmetrymagazine.org/article/august-2015/
icecube-sees-highest-energy-neutrino-ever-found
[7]http://earthsky.org/space/cosmic-neutrinos-confirmed-at-south-pole
Georgia Karagiorgi, an associate physics professor at Columbia as saying:
Michael Shaevitz, Karagiorgi is part of a long-running hunt for new types of neutrinos at Fermilab, a national particle accelerator laboratory near Chicago."
the Short- Baseline Neutrino Program.
"Neutrinos traverse our detectors without leaving a trail, but every now and then they collide head-on with an atomic nucleus."
She explains:
The explosion that follows usually produces a spray of charged particles—electrons, muons, and/or protons."
Professor Karagiorgi points out:
"Each charged particle leaves behind a trail of scintillation light and ionization electrons produced by excited atoms along the charged particle's path."
She explains:
"By detecting those trails, we can usually infer the presence of a neutrino, its identity, and how fast and in what direction it’s traveling."
Source:
news
.columbia
.edu|Kim
Martineau|
08
Sep 2021:|
Searching
for
Ghostly
Neutrinos
to
Understand
Why
Matter
Dominates
the
Universe
Scientists Detect
Neutrinos
From Sun’s Core
G. Bellini et al.
Aug 31, 2014
Sci-News.com
A multinational collaboration of physicists has directly detected neutrinos created by the proton-proton fusion process going on at the heart of the Sun.[1]
Physicists have directly detected pp neutrinos, demonstrating that about 99 per cent of the power of the Sun is generated by the pp fusion process.[1]
In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium.[1]
The primary reaction is thought to be the proton-proton (pp) fusion with the emission of a low-energy neutrino.[1]
These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux and stream out of the Sun at nearly the speed of light.[1]
Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from pp fusion have eluded direct detection for decades.[1]
David W. Casper
The School of Physical Sciences
The University of California, Irvine
Neutrinos are one of the fundamental particles which make up the universe. They are also one of the least understood.[2]
Neutrinos are similar to the more familiar electron, with one crucial difference: neutrinos do not carry electric charge. [2]
1931 - A hypothetical particle is predicted by the theorist Wolfgang Pauli.[2]
Pauli based his prediction on the fact that energy and momentum did not appear to be conserved in certain radioactive decays.[2]
Pauli suggested that this missing energy might be carried off, unseen, by a neutral particle which was escaping detection.[2]
Because neutrinos are electrically neutral, they are not affected by the electromagnetic forces which act on electrons.[2]
Neutrinos are affected only by a "weak" sub-atomic force of much shorter range than electromagnetism, and are therefore able to pass through great distances in matter without being affected by it.[2]
If neutrinos have mass, they also interact gravitationally with other massive particles, but gravity is by far the weakest of the four known forces.[2]
Three types of neutrinos are known; there is strong evidence that no additional neutrinos exist, unless their properties are unexpectedly very different from the known types. [2]
Each type or "flavor" of neutrino is related to a charged particle (which gives the corresponding neutrino its name). [2]
Hence, the "electron neutrino" is associated with the electron, and two other neutrinos are associated with heavier versions of the electron called the muon and the tau (elementary particles are frequently labelled with Greek letters, to confuse the layman). [2]
1989 - Kamiokande becomes the second experiment to detect neutrinos from the Sun, and confirms the long-standing anomaly by finding only about 1/3 the expected rate.[2]
1997 - Super-Kamiokande reports a deficit of cosmic-ray muon neutrinos and solar electron neutrinos, at rates agreeing with measurements by earlier experiments. [2]
1998 - The Super-Kamiokande collaboration announces evidence of non-zero neutrino mass at the Neutrino '98 conference.[2]
My research is focused on the most fundamental known constituents and forces of nature. [2]
The goal of elementary particle physics is to unify, if possible, the laws of nature into a single consistent, economical description.[3]
One area of recent excitement concerns neutrinos - electrically neutral versions of the more familiar electron, which are able to pass through enormous amounts of matter without interacting.[3]
With the Super-Kamiokande experiment in Japan, my colleagues and I have shown that these ghostly particles, long-believed to be perfectly massless, not only carry mass but change their very character ("oscillate") as they whiz through space.[3]
In a related experiment called K2K, we have shot a man-made beam of neutrinos through the earth, to a detector 250 km away, further confirming the original discovery.[3]
A second-generation experiment, T2K, will measure the mixing between neutrinos, and their masses, more precisely, and hopefully discover a new and predicted mode of oscillation. [3]
By understanding what makes neutrinos oscillate, we hope to uncover new evidence for the "theory of everything", and may explain why the universe consists almost entirely of matter, rather than anti-matter.[3]
nature
.com|
David
Castelvecchi|
16
July
2021:
The
vanishing
neutrinos
that
could
upend
fundamental
physics
Neutrino Birth:
Wolfgang Pauli
4 December 1930
Neutrino Mysteries, Surprises and Promises
Carlo Giunti
Organiser:
Francesca Di Lodovico
INFN, Sezione di Torino
&
Dipartimento di Fisica Teorica
Universit`a di Torino
ESOF, Torino
4 July 2010
4 December 1930: Wolfgang Pauli sent a Public letter to the group of the Radioactives at the district society meeting in Tueubingen
Dear Radioactive Ladies and Gentlemen
. . . I have hit upon a desperate remedy to save . . . the law of
conservation of energy. Namely, the possibility that there could exist in the nuclei electrically neutral particles, that I wish to call neutrons . . .The continuous -spectrum would then become understandable by the assumption that in -decay, a neutron is emitted in addition to the electron such that the sum of the
energies of the neutron and electron is constant.[4]
1933: Enrico Fermi proposes the name neutrino (italian: small neutron) at the Solvay Congress in Brussels.1934: Enrico Fermi formulates A Theory of Beta Radiation which is the theory of Weak Interactions. Neutrinos interact only with Weak Interactions =)Very difficult to detect (maybe impossible; H. Bethe and R. Peierls, 1934).[4]
The neutrino mass much be much smaller than the electron mass. Maybe the neutrino is massless. Fermi received the 1938 Physics Nobel Prize “for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons.”[4]
From what we know today, a majority of the neutrinos floating around were born around 15 billions years ago, soon after the birth of the universe.The neutrino was first postulated in December, 1930 by Wolfgang Pauli to explain the energy spectrum of beta decays, the decay of a neutron into a proton and an electron.[5]
Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed.[5]
In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science, a result that was rewarded with the 1995 Nobel Prize. [5]
Ice Cube
sees
Highest-Energy Neutrino Ever Found
Kathryn Jepsen
August 04, 2015
In 2013, the IceCube neutrino experiment at the South Pole reported the observation of two ultra-high-energy neutrino events, which they named after Sesame Street characters Bert and Ernie. Later, they found one more.[6]
Today IceCube scientists reported the observation of an even higher-energy neutrino event, one that offers scientists the best hope yet that they will be able to use ultra-high-energy neutrinos to find the source of ultra-high-energy cosmic rays. The neutrino event had an energy of more than 2000 trillion electronvolts.[6]
For more than a century, scientists have known that particles called cosmic rays rain down on the Earth from space. Some of these cosmic rays slam into our atmosphere at energies higher than we could possibly reach in any earthly particle accelerator.[6]
It is still a mystery where these particles come from, but it seems that they are from energetic sources outside our galaxy. One suspicion is that they are coming from active galaxies swirling around distant black holes.[6]
Cosmic rays are charged particles, which means that their paths bend and shift as they pass through magnetic fields in space. That makes it difficult to trace their origins.[6]
That’s where neutrinos come in. Neutrinos are neutral, rarely interacting particles that can pass through entire planets without changing course.[6]
Ultra-high-energy neutrinos that the IceCube experiment observes could be coming from the same sources as ultra-high-energy cosmic rays. If so, they could point the way back to those sources.[6]
“This opens the neutrino astronomy field,” says Fermilab neutrino scientist Anne Schukraft, a former member of the IceCube collaboration.Neutrinos come in three types, called flavors: electron, muon and tau. [6]
When electron and tau neutrinos interact with the ice around the IceCube neutrino detector, their energy appears to balloon out from their interaction points, making it difficult to figure out exactly where they came from.[6]
Cosmic Neutrinos Confirmed at South Pole
EarthSky
Human World, Science Wire, Space
Aug 25, 2015
Researchers say these high-energy neutrinos come from sources beyond our Milky Way galaxy. They say the ability to discover them heralds a new form of astronomy.[7]
Researchers at the South Pole – using a cubic-kilometer particle detector embedded in Antarctic ice – say they have provided independent confirmation of a 2013 sighting of cosmic neutrinos. [7]
These ultra high-energy particles are thought to have traversed space unimpeded by stars, planets, galaxies, magnetic fields or clouds of interstellar dust before their detection by the IceCube Neutrino Observatory at the South Pole.[7]
Did this telescope actually detect the neutrinos? No. It detected secondary particles – called muons – created on the rare occasions when neutrinos interact with matter. Still, it’s a formidable piece of research, published on August 20, 2015 in the journal Physical Review Letters. [7]
There are some mightily cool aspects of this far-southern study. The telescope at the South Pole, for example, is unlike any other on Earth.[7]
The IceCube Neutrino Observatory is composed of thousands of optical sensors sunk deep beneath Antarctic ice. [7]
It’s designed to look through the Earth to observe the Northern Hemisphere sky. In this way, Earth acts as a filter to help weed out a confusing background of muons created when cosmic rays crash into the Earth’s atmosphere. [7]
Francis Halzen, a University of Wisconsin, Madison, professor of physics and the principal investigator of IceCube, said:Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy, and it has delivered. [7]
This is as close to independent confirmation as one can get with a unique instrument.[7]
[1]http://www.sci-news.com/physics/science-neutrinos-suns-core-02125.html
[2]http://www.ps.uci.edu/~superk/neutrino.html
[3]http://www.faculty.uci.edu/profile.cfm?faculty_id=4796
[4]http://www.nu.to.infn.it/slides/2010/giunti-100704-esof.pdf
[5]https://icecube.wisc.edu/info/neutrinos
[6]http://www.symmetrymagazine.org/article/august-2015/
icecube-sees-highest-energy-neutrino-ever-found
[7]http://earthsky.org/space/cosmic-neutrinos-confirmed-at-south-pole
A multinational collaboration of physicists has directly detected neutrinos created by the proton-proton fusion process going on at the heart of the Sun.[1]
Physicists have directly detected pp neutrinos, demonstrating that about 99 per cent of the power of the Sun is generated by the pp fusion process.[1]
In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium.[1]
The primary reaction is thought to be the proton-proton (pp) fusion with the emission of a low-energy neutrino.[1]
These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux and stream out of the Sun at nearly the speed of light.[1]
Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from pp fusion have eluded direct detection for decades.[1]
Neutrinos are one of the fundamental particles which make up the universe. They are also one of the least understood.[2]
Neutrinos are similar to the more familiar electron, with one crucial difference: neutrinos do not carry electric charge. [2]
1931 - A hypothetical particle is predicted by the theorist Wolfgang Pauli.[2]
Pauli based his prediction on the fact that energy and momentum did not appear to be conserved in certain radioactive decays.[2]
Pauli suggested that this missing energy might be carried off, unseen, by a neutral particle which was escaping detection.[2]
Because neutrinos are electrically neutral, they are not affected by the electromagnetic forces which act on electrons.[2]
Neutrinos are affected only by a "weak" sub-atomic force of much shorter range than electromagnetism, and are therefore able to pass through great distances in matter without being affected by it.[2]
If neutrinos have mass, they also interact gravitationally with other massive particles, but gravity is by far the weakest of the four known forces.[2]
Three types of neutrinos are known; there is strong evidence that no additional neutrinos exist, unless their properties are unexpectedly very different from the known types. [2]
Each type or "flavor" of neutrino is related to a charged particle (which gives the corresponding neutrino its name). [2]
Hence, the "electron neutrino" is associated with the electron, and two other neutrinos are associated with heavier versions of the electron called the muon and the tau (elementary particles are frequently labelled with Greek letters, to confuse the layman). [2]
1989 - Kamiokande becomes the second experiment to detect neutrinos from the Sun, and confirms the long-standing anomaly by finding only about 1/3 the expected rate.[2]
1997 - Super-Kamiokande reports a deficit of cosmic-ray muon neutrinos and solar electron neutrinos, at rates agreeing with measurements by earlier experiments. [2]
1998 - The Super-Kamiokande collaboration announces evidence of non-zero neutrino mass at the Neutrino '98 conference.[2]
My research is focused on the most fundamental known constituents and forces of nature. [2]
The goal of elementary particle physics is to unify, if possible, the laws of nature into a single consistent, economical description.[3]
One area of recent excitement concerns neutrinos - electrically neutral versions of the more familiar electron, which are able to pass through enormous amounts of matter without interacting.[3]
With the Super-Kamiokande experiment in Japan, my colleagues and I have shown that these ghostly particles, long-believed to be perfectly massless, not only carry mass but change their very character ("oscillate") as they whiz through space.[3]
In a related experiment called K2K, we have shot a man-made beam of neutrinos through the earth, to a detector 250 km away, further confirming the original discovery.[3]
A second-generation experiment, T2K, will measure the mixing between neutrinos, and their masses, more precisely, and hopefully discover a new and predicted mode of oscillation. [3]
By understanding what makes neutrinos oscillate, we hope to uncover new evidence for the "theory of everything", and may explain why the universe consists almost entirely of matter, rather than anti-matter.[3]
4 December 1930: Wolfgang Pauli sent a Public letter to the group of the Radioactives at the district society meeting in Tueubingen
Dear Radioactive Ladies and Gentlemen
1933: Enrico Fermi proposes the name neutrino (italian: small neutron) at the Solvay Congress in Brussels.1934: Enrico Fermi formulates A Theory of Beta Radiation which is the theory of Weak Interactions. Neutrinos interact only with Weak Interactions =)Very difficult to detect (maybe impossible; H. Bethe and R. Peierls, 1934).[4]
The neutrino mass much be much smaller than the electron mass. Maybe the neutrino is massless. Fermi received the 1938 Physics Nobel Prize “for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons.”[4]
From what we know today, a majority of the neutrinos floating around were born around 15 billions years ago, soon after the birth of the universe.The neutrino was first postulated in December, 1930 by Wolfgang Pauli to explain the energy spectrum of beta decays, the decay of a neutron into a proton and an electron.[5]
Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed.[5]
In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science, a result that was rewarded with the 1995 Nobel Prize. [5]
In 2013, the IceCube neutrino experiment at the South Pole reported the observation of two ultra-high-energy neutrino events, which they named after Sesame Street characters Bert and Ernie. Later, they found one more.[6]
Today IceCube scientists reported the observation of an even higher-energy neutrino event, one that offers scientists the best hope yet that they will be able to use ultra-high-energy neutrinos to find the source of ultra-high-energy cosmic rays. The neutrino event had an energy of more than 2000 trillion electronvolts.[6]
For more than a century, scientists have known that particles called cosmic rays rain down on the Earth from space. Some of these cosmic rays slam into our atmosphere at energies higher than we could possibly reach in any earthly particle accelerator.[6]
It is still a mystery where these particles come from, but it seems that they are from energetic sources outside our galaxy. One suspicion is that they are coming from active galaxies swirling around distant black holes.[6]
Cosmic rays are charged particles, which means that their paths bend and shift as they pass through magnetic fields in space. That makes it difficult to trace their origins.[6]
That’s where neutrinos come in. Neutrinos are neutral, rarely interacting particles that can pass through entire planets without changing course.[6]
Ultra-high-energy neutrinos that the IceCube experiment observes could be coming from the same sources as ultra-high-energy cosmic rays. If so, they could point the way back to those sources.[6]
“This opens the neutrino astronomy field,” says Fermilab neutrino scientist Anne Schukraft, a former member of the IceCube collaboration.Neutrinos come in three types, called flavors: electron, muon and tau. [6]
When electron and tau neutrinos interact with the ice around the IceCube neutrino detector, their energy appears to balloon out from their interaction points, making it difficult to figure out exactly where they came from.[6]
Researchers say these high-energy neutrinos come from sources beyond our Milky Way galaxy. They say the ability to discover them heralds a new form of astronomy.[7]
Researchers at the South Pole – using a cubic-kilometer particle detector embedded in Antarctic ice – say they have provided independent confirmation of a 2013 sighting of cosmic neutrinos. [7]
These ultra high-energy particles are thought to have traversed space unimpeded by stars, planets, galaxies, magnetic fields or clouds of interstellar dust before their detection by the IceCube Neutrino Observatory at the South Pole.[7]
Did this telescope actually detect the neutrinos? No. It detected secondary particles – called muons – created on the rare occasions when neutrinos interact with matter. Still, it’s a formidable piece of research, published on August 20, 2015 in the journal Physical Review Letters. [7]
There are some mightily cool aspects of this far-southern study. The telescope at the South Pole, for example, is unlike any other on Earth.[7]
The IceCube Neutrino Observatory is composed of thousands of optical sensors sunk deep beneath Antarctic ice. [7]
It’s designed to look through the Earth to observe the Northern Hemisphere sky. In this way, Earth acts as a filter to help weed out a confusing background of muons created when cosmic rays crash into the Earth’s atmosphere. [7]
Francis Halzen, a University of Wisconsin, Madison, professor of physics and the principal investigator of IceCube, said:Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy, and it has delivered. [7]
[1]http://www.sci-news.com/physics/science-neutrinos-suns-core-02125.html
[2]http://www.ps.uci.edu/~superk/neutrino.html
[3]http://www.faculty.uci.edu/profile.cfm?faculty_id=4796
[4]http://www.nu.to.infn.it/slides/2010/giunti-100704-esof.pdf
[5]https://icecube.wisc.edu/info/neutrinos
[6]http://www.symmetrymagazine.org/article/august-2015/
icecube-sees-highest-energy-neutrino-ever-found
[7]http://earthsky.org/space/cosmic-neutrinos-confirmed-at-south-pole
