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Detecting Neutrinos

1 Standard Model

This is section 1 of 13.

The Standard Model is the currently accepted mix of subatomic particles.

This book refers to more particles than just a neutrino.

This section offers some of that background.

The widely accepted atomic model is called the Standard Model.

It defines a variety of particles and quasi-particles.

Click on the link to read its complete description.

Standard Model

Rather than listing them, here is a copy of an image presenting all of the elementary particles in the Standard Model.
This book is about neutrinos.

Click on the link to zoom as needed.

Standard Model  of Elementary Particles\wiki-SM-PP.png

Here is an image presenting the particles as generations of matter.

Click on the link to zoom as needed.

Generations of Matter\wiki-Gen-Matter.png

Both images are copies from Wikipedia, using the link to Standard Model topic, or Generations of Matter topic.


Generations of Matter

The relvant particles will be described.

1.1 Electron

 The electron is a subatomic particle, symbol 
e  or e-, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure.



The electron is elementary only because particle colliders have been unable to find a way to break one.

Even the use of "generally thought" confirms this rule is based on a judgment, and is subject to change.

1.1 Electron's Mass

The electron mass is relevant because this value can be compared to other particles, like neutrinos.

Here is its description.

The electron mass (symbol: me) is the mass of a stationary electron, also known as the invariant mass of the electron.

It is a fundamental constants of physics.

It has a value of about 9.109×10^-31 kilograms or about 5.486×10^-4 daltons, equivalent to an energy of about 8.187×10^-14 joules or about 0.5110 MeV.



Some other particles have their mass in the units of MEV/c^2, not MEV, as shown shown above value for me.

1.2 Proton

A proton is a subatomic particle, symbol p or p^+, with a positive electric charge of +1e elementary charge and a mass slightly less than that of a neutron."

Although protons were originally considered fundamental or elementary particles, in the modern Standard Model of particle physics, protons are classified as hadrons, like neutrons, the other nucleon.

Protons are composite particles composed of three valence quarks: two up quarks of charge +2/3e and one down quark of charge -1/3e.

The rest masses of quarks contribute only about 1% of a proton's mass. The remainder of a proton's mass is due to quantum chromodynamics binding energy, which includes the kinetic energy of the quarks and the energy of the gluon fields that bind the quarks together. Because protons are not fundamental particles, they possess a measurable size; the root mean square charge radius of a proton is about 0.84 to 0.87 fm (or 0.84×10^-15 m to 0.87×10^-15 m). 

In 2019, two different studies, using different techniques, have found the radius of the proton to be 0.833 fm, with an uncertainty of +/- 0.010 fm.



The quarks do not sum up to the mass of a proton. They have only 1%.

When quarks are the claimed components of a proton, the claim immediately fails. A proton needs much more than these fragments to be capable of explaining its observed behaviors.

This book, like my others about particle physics, treats quarks as just debris and not as fundamental partticles in an atomic model.

They contribute nothing to our understanding an atom and its behaviors which are driven by a nucleus and its accompanying electron configuration.

1.3 Neutron

Here is the basic description of a neutron.

The neutron is a subatomic particle, symbol 
n  or n^0, which has a neutral (not positive or negative) charge and a mass slightly greater than that of a proton.



The following statement is not in any on-line reference, because it is the conclusion of this book and my other books on particle physics.

A neutron is a proton with an adjacent electron, having surface contact. A neutron is not 1 distinct particle.It is 2.

This image and caption are copied from the topic of Neutron, cited above.

Neutron in Standard Model

Its caption:

The quark content of the neutron. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

This image and caption are important.

In the Standard Model, a neutron is a single particle, where the quarks of the proton and electron have merged within a membrane, held together by glouns.

This assumption is important in the section Fermi's Interaction.

1.4 Neutrino

Here is the basic description of a neutrino.

A neutrino (denoted by the Greek letter nu or v) is a fermion (an elementary particle with spin of 1/2) that interacts only via the weak subatomic force and gravity. 
The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero.
The mass of the neutrino is much smaller than that of the other known elementary particles.

Neutrinos [are] in one of three leptonic flavors: electron neutrinos, muon neutrinos, or tau neutrinos, in association with the corresponding charged lepton
Although neutrinos were long believed to be massless, it is now known that there are three discrete neutrino masses with different tiny values, but they do not correspond uniquely to the three flavors. 



A neutrino is elementary only because it was never broken into pieces. There is no observed decay.
The mass remains "tiny" for each neutrino. This lack of definition is awkward for its "elementary" status.
The neutrino types will be described in more detail later.

The respective flavors of neutrinos have their own section.

Stanford has a web page with this title and beginning:


The following is a short history of neutrinos as it relates to neutrino oscillation studies.



The web page does not identify its date.

I will use some of these events in this book. Others might find it useful.

1.5 Neutron

Here is the basic description of a neutron.

The neutron is a subatomic particle, symbol n  or  n^0
which has a neutral (not positive or negative) charge and a mass slightly greater than that of a proton.
Protons and neutrons constitute the nuclei of atoms.

Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics.



This book assumes an atom consists of protons and electrons in the nucleus with other electrons in orbit around it, in a configuration called shells.

A neutron is created in the nucleus by a surface contact bond between a proton and an adjacent electron. They have an opposing charge.

When a neutron is not in the nucleus, this force is not sufficient for a permanent bond. The disintegration into the original 2 particles occurs within a few minutes. This slow decay is evidence of that lack of permanence.

This decay occurs because the particle pair, when isolated from contact with other particles within a nucleus, is subject to any external electric or gravity fields present at the neutron causing a mutual force, which diminishes by inverse-square of mutual distance to the other particles.

The variable time for eventual decay depends on the environment for the neutron outside the atom.

Reference: in section My Publications, see Mass and Gravity

When a neutron is compressed together with a proton, or fused together, the result is deuterium or  2H, then the electron is firmly attached to both protons, because the atom 2H does not decay.
Doubling the mutual electrostatic force and gravity maintains the electron in the nucleus. Fusing another proton to deuterium increases the positive charge in the nucleus and 3He is stable, so its neutrons remain intact. In this triple, the single electron has physical contact with 3 protons, which are also in mutual contact.

The nucleus in deuterium suggests the electrostatic force of repulsion between 2 protons is overcome by physical contact between the 2 protons.

The equation in Coulomb's Law has distance in the denominator resulting in an ambigous, infinity vlalue.

There is no observation of 2 electrons holding physical contact.

The protons are much more massive, suggesting gravity between protons is a contributing factor to stability within a nucleus.

This behavior was also described in my book Practical Atomic Model, which is mentioned in section My Relvant Publications.
Section 15 Periodic Table in that book calculates the mass of a neutron in many isotopes and its value is never greater than expected.

However, the public value of a neutron's mass was measured indirectly using a deuterium atom so its accuracy could be questioned before making any conclusions about it.

The measured mass of a neutron has been calculated many times, for many isotopes. The values are not consistent.

I did this exercise in an Excel spreadsheet for my book, Practical Atomic Model, referenced above.

I excerpted the section of Atomic Mass Defect from my book into a free pdf. titled Atomic Mass Defect Alternative.

See section My Publications for details of the book or the pdf.

Atomic Mass Defect (AMD) is not important to this book's topic of neutrinos, except with any reference to nuclear binding rnergy.

My AMD has an alternate explanation of an atomic behavior without a loss of mass which was converted to a new form of energy, called nuclear binding energy, from the missing mass in the calculation.

Mass must be conserved in an atomic model. There is no evidence for an entity called nuclear binding energy.

It is reasonable to conclude the decrease in a neutron's reactivity to another mass, during a bond between particles, occurs in the proton, not the electron.
The electron is somewhat attached to the much more massive proton (by 1836 times), while the protons are compressed together by an external force of fusion to get them adjacent within the nucleus. The external force must overcome the mutual repulsion between protons, by the electrostatic force.

The result of neutrality after this compression indicates the 2 separate charge components of opposite polarity remain intact, while observed as a neutron.

This explains its net charge of zero, and the separate polarities are maintained, before and after disintegration.

Beta minus decay is a neutron decaying into a proton, electron, and electron neutrino.

(end of observation; resume excerpt)

However, this decay cannot be measured with precision.

The number is not well-enough measured to determine the comparatively tiny rest mass of the neutrino (which must in theory be subtracted from the maximal electron kinetic energy); furthermore, neutrino mass is constrained by many other methods.

A small fraction (about one in 1000) of free neutrons decay with the same products, but add an extra particle in the form of an emitted gamma ray.

This gamma ray may be thought of as a sort of "internal bremsstrahlung" that arises as the emitted beta particle (electron) interacts with the charge of the proton in an electromagnetic way. In this process, some of the decay energy is carried away as photon energy. Internal bremsstrahlung gamma ray production is also a minor feature of beta decays of bound neutrons, that is, those within a nucleus.

A very small minority of neutron decays (about four per million) are so-called "two-body (neutron) decays", in which a proton, electron and antineutrino are produced as usual, but the electron fails to gain the 13.6 eV necessary energy to escape the proton (the ionization energy of hydrogen), and therefore simply remains bound to it, as a neutral hydrogen atom (one of the "two bodies"). In this type of free neutron decay, in essence all of the neutron decay energy is carried off by the antineutrino (the other "body").

Research is intense in the hunt to elucidate the essential nature of neutrinos, with aspirations of finding:

* the three neutrino mass values

* the degree of CP violation in the leptonic sector (which may lead to leptogenesis)

* evidence of physics which might break the Standard Model of particle physics, such as neutrinoless double beta decay, which would be evidence for violation of lepton number conservation.



Leptogenesis is the process of creating matter, in the form of leptons in the Standard Model.

There is a stated concern with lepton number conservation. This concern of conservation of attributes will arise when describing the mechanism of a neutrino's creation.

The origin of a neutrino will be described in detail..

A gamma ray is energy in a very short wavelength of electromagnetic radiation,  and is not a particle. Gamma ray generation is complex.

Neutrinos are not well understood, but the Standard Model expects that a beta decay event results in 1 neutrino.

A neutron is an adjacent proton and electron. When they bind the resulting mass is unverified because an object having no charge cannot be measured by techniques using electromagnetism to control the particle, but it should be the sum of proton mass plus electron mass.

The topic for beta decay while in a nucleus never mentions a gamma ray emission.

The reason for including this beta decay description is the creation of this neutrino in this particular scenario is important. Both the proton and electron are cohesive bodies, with both capable of reacting to both charge and mass.

The proton, as implied from measurements done by others, can be slightly compressed when measuring the sizes of atomic nuclei. That size reduction indicates inherent structure and surface.

The 2 particles are held together by Coulomb's force between charges. When this physical connection between surfaces is broken, somehow a neutrino particle possessing the mass behavior is created. Unfortunately, a measurement of its mass is never available.

One can imagine a behavior like the proton sheds a flake of its surface from the break between contact and this flake has enough material to be capable of reacting to other masses. Unfortunately, this is an unacceptable explanation when leading to deterioration of protons.

When reading descriptions of events involving neutrinos, it is almost impossible to determine whether a neutrino exists in a particle equation only to balance the quarks.  A free neutron results from a step in the radioactive decay of isotopes with excess neutrons. If every free neutron emits a neutrino on its break-up, there could be many being emitted.
One could question whether they have been consistently detected to confirm the theory's prediction. When considering an atomic model with no quarks, a neutron is only a proton and electron, so the detection of these neutrinos in the description is important.

1.5.1 Neutron's mass

One might expect the mass of a neutron is measured directly. That is not the case. Its value uses the assumption of nuclear binding energy which this book suggests is not really as claimed.

The mass of a neutron cannot be directly determined by mass spectrometry due to lack of electric charge. However, since the masses of a proton and of a deuteron can be measured with a mass spectrometer, the mass of a neutron can be deduced by subtracting proton mass from deuteron mass, with the difference being the mass of the neutron plus the binding energy of deuterium (expressed as a positive emitted energy). The latter can be directly measured by measuring the single 0.7822 MeV gamma photon emitted when neutrons are captured by protons (this is exothermic and happens with zero-energy neutrons), plus the small recoil kinetic energy) of the deuteron (about 0.06% of the total energy).
The energy of the gamma ray can be measured to high precision by X-ray diffraction techniques, as was first done by Bell and Elliot in 1948.
 The best modern (1986) values for neutron mass by this technique are provided by Greene, et al. 
These give a neutron mass of:

[mass] neutron = 1.008644904 u

The value for the neutron mass in MeV is less accurately known, due to less accuracy in the known conversion of u to MeV:

[mass] neutron = 939.56563 MeV/c^2.

Another method to determine the mass of a neutron starts from the beta decay of the neutron, when the momenta of the resulting proton and electron are measured.



There are many assumptions to get the precise result, including a recognized issue with the "less accuracy" of the conversion from a gamma ray wave length to its equivalent mass.

The mass defect behavior is driven by a nucleus having more than 1 proton, as only Protium has no mass defect when using my recommended mass for a proton, because only protium has only 1 nucleon, 1 proton. The measured mass of a neutron was calculated by using deuterium which has 2  protons and 1 electron in its nucleus, so the conditions inherently involved a mass defect, which is a behavior misunderstood in the Standard Model.

This brings into doubt whether the neutron's measured mass, defined with much precision, is actually verified to that accuracy.

Calculations using many significant digits must beware factors lacking the precision of other values when claiming the final precision.

The neutron behaves like 2 distinct particles but when in a nucleus, it can exhibit a reduced reactivity to other masses. This is the conclusion after the comparison between the 2 atoms having similar nucleon counts.

The 2 distinct charge behaviors appear intact, but the reactivity to other masses is changed slightly only while compressed.

When the split of a neutron occurs, each charge components gets its original mass reactivity component.

The split is accompanied by a neutrino having little or no mass reactivity and no charge reactivity.

When an electron and proton unite to form a neutron, the mass reactivity, from the accepted value) is less than the sum.

This confirms the mass behavior is not just an addition. The mass reactivity of a neutron is not driven by the sum at its creation. In other words, a neutron can exhibit a difference in its expected mass while in a nucleus. This is called a mass defect.

Mass defect was explained in one of my books, Practical Particle Physics.

Part of that book was extracted into a separate pdf.

If interested in that topic unrelated to a neutrino, please read Atomic Mass Defect Alternativeidentified  in section My Relevant Publications.

Details of the book are also in that section.

Mass defect in a nucleus is not important to neutrinos.

1.6 Muon

Here is its basic description.

The muon from the Greek letter mu (u) used to represent it) is an elementary particle similar to the electron, with an electric charge of -1 e and a spin of 1/2, but with a much greater mass. It is classified as a lepton. As with other leptons, the muon is not known to have any sub-structure – that is, it is not thought to be composed of any simpler particles.

The muon is an unstable subatomic particle with a mean lifetime of 2.2 us, much longer than many other subatomic particles. As with the decay of the non-elementary neutron (with a lifetime around 15 minutes), muon decay is slow (by subatomic standards) because the decay is mediated only by the weak interaction (rather than the more powerful strong interaction or electromagnetic interaction), and because the mass difference between the muon and the set of its decay products is small, providing few kinetic degrees of freedom for decay. Muon decay almost always produces at least three particles, which must include an electron of the same charge as the muon and two types of neutrinos.

Like all elementary particles, the muon has a corresponding antiparticle of opposite charge (+1 e) but equal mass and spin: the antimuon (also called a positive muon). Muons are denoted by
 and antimuons by
. Formerly, muons were called "mu mesons", but are not classified as mesons by modern particle physicists, and that name is no longer used by the physics community.

Muons have a mass of 105.66 MeV/c^2, which is approximately 207 times that of the electron, me. More precisely, it is 206.7682830(46) me.

Due to their greater mass, muons accelerate more slowly than electrons in electromagnetic fields, and emit less bremsstrahlung (deceleration radiation). This allows muons of a given energy to penetrate far deeper into matter because the deceleration of electrons and muons is primarily due to energy loss by the bremsstrahlung mechanism. For example, so-called "secondary muons", created by cosmic rays hitting the atmosphere, can penetrate the atmosphere and reach Earth's land surface and even into deep mines.

Because muons have a greater mass and energy than the decay energy of radioactivity, they are not produced by radioactive decay. However they are produced in great amounts in high-energy interactions in normal matter, in certain particle accelerator experiments with hadrons, and in cosmic ray interactions with matter. These interactions usually produce pi mesons initially, which almost always decay to muons.

As with the other charged leptons, the muon has an associated muon neutrino, denoted by
µ, which differs from the electron neutrino and participates in different nuclear reactions.


The existence of the muon breaks the Standard Model which assumes quarks are the fundamental particles. Quarks are found only as debris in particle accelerators. They exist in no other place. They contribute nothing to our understanding of atomic behaviors.

A muon is found only in the debris of a particle accelerator.

The high velocity atomic nuclei in cosmic rays are a type of particle accelerator.

A muon can be found in the debris of these collisions. Rather than 3 quarks, the muon is an intact particle having both mass and charge.

Since it has more mass than an electron, the muon is a damaged proton.
The charge behavior within this particle flipped its polarity to negative.

The mass behavior within this muon particle is reduced by the damage.

My analysis of the atomic mass defect measurements concluded a proton is compressed in size causing a reduction in its measured mass.

There is no actual  loss of mass, just transient compression.

When particle accelerators are used to create new isotopes by adding nucleons, the atoms can be measured before and after. Sometimes protons or neutrons are ejected from the nucleus. when it seeks stability.

There is no evidence for protons to remain at the lower mass measured under compression, when that compression is relieved outside the nucleus.

1.7 Taon

Here is the description of tauon.

The tau (tau), also called the tau lepton, tau particle, or tauon, is an elementary particle similar to the electron, with negative electric charge and a spin of 1/2.

Like the electron, the muon, and the three neutrinos, the tau is a lepton, and like all elementary particles with half-integer spin, the tau has a corresponding antiparticle of opposite charge but equal mass and spin. In the tau's case, this is the "antitau" (also called the positive tau). Tau particles are denoted by the symbol
 and the antitaus by

Tau leptons have a lifetime of 2.9×10^-13 s and a mass of 1776.86 MeV/c^2 (compared to 105.66 MeV/c^2 for muons and 0.511 MeV/c^2 for electrons). Since their interactions are very similar to those of the electron, a tau can be thought of as a much heavier version of the electron. Because of their greater mass, tau particles do not emit as much bremsstrahlung radiation as electrons; consequently they are potentially much more highly penetrating than electrons.

Because of its short lifetime, the range of the tau is mainly set by its decay length, which is too small for bremsstrahlung to be noticeable. Its penetrating power appears only at ultra-high velocity and energy (above petaelectronvolt energies), when time dilation extends its otherwise very short path-length.

As with the case of the other charged leptons, the tau has an associated tau neutrino, denoted by



The tauon breaks the Standard Model for the same reasons as the muon. The tauon is a particle having a mass between proton and electron, so the 3 quark combination for a proton can't also explain the lower value for a tauon. Though the taon decays, it remained intact for a short time.

The Standard Model does not address how individual quarks maintain the integrity of their particle.

The DONUT Collaboration is described in the section Neutrino Detectors.

1.8 Neutrino

This particle is the reason for writing this book.

Here is its description.


There are 3 types or flavors of a neutrino. Each is explained in their own section.

Go to Table of Contents, to read a specific section.

last change 04/03/2022