Nick Connor, Author at Radiation Dosimetry

What is Shielding of Ionizing Radiation – Definition

December 14, 2019 by Nick Connor

Shielding of ionizing radiation simply means having some material between the source of radiation and you (or some device) that will absorb the radiation. Radiation Dosimetry

Radiation protection is the science and practice of protecting people and the environment from the harmful effects of ionizing radiation. It is a serious topic not only in nuclear power plants, but also in industry or in medical centres. In radiation protection there are three ways how to protect people from identified radiation sources:

Limiting Time. The amount of radiation exposure depends directly (linearly) on the time people spend near the source of radiation. The dose can be reduced by limiting exposure time.
Distance. The amount of radiation exposure depends on the distance from the source of radiation. Similarly to a heat from a fire, if you are too close, the intensity of heat radiation is high and you can get burned. If you are at the right distance, you can withstand there without any problems and moreover it is comfortable. If you are too far from heat source, the insufficiency of heat can also hurt you. This analogy, in a certain sense, can be applied to radiation also from radiation sources.
Shielding. Finally, if the source is too intensive and time or distance do not provide sufficient radiation protection, the shielding must be used. Radiation shielding usually consist of barriers of lead, concrete or water. There are many many materials, which can be used for radiation shielding, but there are many many situations in radiation protection. It highly depends on the type of radiation to be shielded, its energy and many other parametres. For example, even depleted uranium can be used as a good protection from gamma radiation, but on the other hand uranium is absolutely inappropriate shielding of neutron radiation.

radiation protection pronciples - time, distance, shielding — Principles of Radiation Protection – Time, Distance, Shielding

Radiation shielding simply means having some material between the source of radiation and you (or some device) that will absorb the radiation. The amount of shielding required, the type or material of shielding strongly depends on several factors. We are not talking about any optimisation.

In fact in some cases an inappropriate shielding may even worsen the radiation situation instead of protecting people from the ionizing radiation. Basic factors, which have to be considered during proposal of radiation shielding, are:

Type of the ionizing radiation to be shielded
Energy spectrum of the ionizing radiation
Length of exposure
Distance from the source of the ionizing radiation
Requirements on the attenuation of the ionizing radiation – ALARA or ALARP principles
Design degree of freedom
Other physical requirements (e.g. transparence in case of leaded glass screens)

Shielding of Radiation in Nuclear Power Plants

Generally in nuclear industry the radiation shielding has many purposes. In nuclear power plants the main purpose is to reduce the radiation exposure to persons and staff in the vicinity of radiation sources. In NPPs the main source of radiation is conclusively the nuclear reactor and its reactor core. Nuclear reactors are in generall powerful sources of entire spectrum of types of ionizing radiation. Shielding used for this purpose is called biological shielding.

But this is not the only purpose of radiation shielding. Shields are also used in some reactors to reduce the intensity of gamma rays or neutrons incident on the reactor vessel. This radiation shielding protects the reactor vessel and its internals (e.g. the core support barrel) from the excessive heating due to gamma ray absorption fast neutron moderation. Such shields are usually referred to as thermal shields.

Characteristics of Gamma Rays

Attenuation coefficients. — Total photon cross sections.
Source: Wikimedia Commons

Key features of gamma rays are summarized in following few points:

Gamma rays are high-energy photons (about 10 000 times as much energy as the visible photons), the same photons as the photons forming the visible range of the electromagnetic spectrum – light.
Photons (gamma rays and X-rays) can ionize atoms directly (despite they are electrically neutral) through the Photoelectric effect and the Compton effect, but secondary (indirect) ionization is much more significant.
Gamma rays ionize matter primarily via indirect ionization.
Although a large number of possible interactions are known, there are three key interaction mechanisms with matter.
Gamma rays travel at the speed of light and they can travel thousands of meters in air before spending their energy.
Since the gamma radiation is very penetrating matter, it must be shielded by very dense materials, such as lead or uranium.
The distinction between X-rays and gamma rays is not so simple and has changed in recent decades. According to the currently valid definition, X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.
Gamma rays frequently accompany the emission of alpha and beta radiation.

Shielding of Gamma Radiation

In short, effective shielding of gamma radiation is in most cases based on use of materials with two following material properties:

high-density of material.
high atomic number of material (high Z materials)

However, low-density materials and low Z materials can be compensated with increased thickness, which is as significant as density and atomic number in shielding applications.

A lead is widely used as a gamma shield. Major advantage of lead shield is in its compactness due to its higher density. On the other hand depleted uranium is much more effective due to its higher Z. Depleted uranium is used for shielding in portable gamma ray sources.

In nuclear power plants shielding of a reactor core can be provided by materials of reactor pressure vessel, reactor internals (neutron reflector). Also heavy concrete is usually used to shield both neutrons and gamma radiation.

Although water is neither high density nor high Z material, it is commonly used as gamma shields. Water provides a radiation shielding of fuel assemblies in a spent fuel pool during storage or during transports from and into the reactor core.

In general, the gamma radiation shielding is more complex and difficult than the alpha or beta radiation shielding. In order to understand comprehensively the way how a gamma ray loses its initial energy, how can be attenuated and how can be shielded we must have detailed knowledge of the its interaction mechanisms.

Water as a neutron shield

Water due to the high hydrogen content and the availability is efective and common neutron shielding. However, due to the low atomic number of hydrogen and oxygen, water is not acceptable shield against the gamma rays. On the other hand in some cases this disadvantage (low density) can be compensated by high thickness of the water shield. In case of neutrons, water perfectly moderates neutrons, but with absorption of neutrons by hydrogen nucleus secondary gamma rays with the high energy are produced. These gamma rays highly penetrates matter and therefore it can increase requirements on the thickness of the water shield. Adding a boric acid can help with this problem (neutron absorbtion on boron nuclei without strong gamma emission), but results in another problems with corrosion of construction materials.

Concrete as a neutron shield

Most commonly used neutron shielding in many sectors of the nuclear science and engineering is shield of concrete. Concrete is also hydrogen-containing material, but unlike water concrete have higher density (suitable for secondary gamma shielding) and does not need any maintenance. Because concrete is a mixture of several different materials its composition is not constant. So when referring to concrete as a neutron shielding material, the material used in its composition should be told correctly. Generally concrete are divided to “ordinary “ concrete and “heavy” concrete. Heavy concrete uses heavy natural aggregates such as barites (barium sulfate) or magnetite or manufactured aggregates such as iron, steel balls, steel punch or other additives. As a result of these additives, heavy concrete have higher density than ordinary concrete (~2300 kg/m³). Very heavy concrete can achieve density up to 5,900 kg/m³ with iron additives or up to 8900 kg/m³ with lead additives. Heavy concrete provide very effective protection against neutrons.

Calculation of Shielded Dose Rate in Sieverts from Contaminated Surface

Assume a surface, which is contamined by 1.0 Ci of ¹³⁷Cs. Assume that this contaminant can be aproximated by the point isotropic source which contains 1.0 Ci of ¹³⁷Cs, which has a half-life of 30.2 years. Note that the relationship between half-life and the amount of a radionuclide required to give an activity of one curie is shown below. This amount of material can be calculated using λ, which is the decay constant of certain nuclide:

About 94.6 percent decays by beta emission to a metastable nuclear isomer of barium: barium-137m. The main photon peak of Ba-137m is 662 keV. For this calculation, assume that all decays go through this channel.

Calculate the primary photon dose rate, in sieverts per hour (Sv.h^-1), at the outer surface of a 5 cm thick lead shield. Then calculate the equivalent and effective dose rates for two cases.

Assume that this external radiation field penetrates uniformly through the whole body. That means: Calculate the effective whole-body dose rate.
Assume that this external radiation field penetrates only lungs and the other organs are completely shielded. That means: Calculate the effective dose rate.

Note that, primary photon dose rate neglects all secondary particles. Assume that the effective distance of the source from the dose point is 10 cm. We shall also assume that the dose point is soft tissue and it can reasonably be simulated by water and we use the mass energy absorption coefficient for water.

Buildup Factors for Gamma Rays Shielding

The buildup factor is a correction factor that considers the influence of the scattered radiation plus any secondary particles in the medium during shielding calculations. If we want to account for the buildup of secondary radiation, then we have to include the buildup factor. The buildup factor is then a multiplicative factor which accounts for the response to the uncollided photons so as to include the contribution of the scattered photons. Thus, the buildup factor can be obtained as a ratio of the total dose to the response for uncollided dose.

The extended formula for the dose rate calculation is:

The ANSI/ANS-6.4.3-1991 Gamma-Ray Attenuation Coefficients and Buildup Factors for Engineering Materials Standard, contains derived gamma-ray attenuation coefficients and buildup factors for selected engineering materials and elements for use in shielding calculations (ANSI/ANS-6.1.1, 1991).

What is Detection of Antineutrinos / Neutrinos – Definition

December 14, 2019 by Nick Connor

Since neutrinos do not ionize matter, they cannot be detected directly. The antineutrino detection is based on the inverse beta decay. Detection of Antineutrinos. Radiation Dosimetry

Since neutrinos do not ionize matter, they cannot be detected directly. The antineutrino detection (1995 Nobel Prize for Frederick Reines and Clyde Cowan) is based on the reaction:

This interaction is symmetrical to the beta decay of free neutron, therefore it sometimes referred to as inverse beta decay. All detection methods require the neutrinos to carry a minimum threshold energy of 1.8 MeV. Only antineutrinos with an energy above the threshold of 1.8 MeV can cause interactions with the protons in the water, producing positrons and neutrons.

Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987.

antineutrino detection — Antineutrino signature: coincidence between prompt positron and delayes neutron capture on hydrogen.
Source: Slides – Dr. Blucher, Enrico Fermi Institute

Antineutrino detector — The inside of a cylindrical antineutrino detector before being filled with clear liquid scintillator, which reveals antineutrino interactions by the very faint flashes of light they emit. Sensitive photomultiplier tubes line the detector walls, ready to amplify and record the telltale flashes.
Photo: Roy Kaltschmidt, LBNL
Source: Daya Bay Reactor Neutrino Experiment

What is Antineutrino – Definition

December 14, 2019 by Nick Connor

Antineutrinos are the antiparticles of neutrinos. The antineutrino is an elementary subatomic particle with infinitesimal mass and with no electric charge. Radiation Dosimetry

Antineutrinos are the antiparticles of neutrinos. The antineutrino is an elementary subatomic particle with infinitesimal mass (less than 0.3eV..?) and with no electric charge. Neutrinos and antineutrinos belong to the family of leptons, which means they do not interact via strong nuclear force. Neutrinos are gravitational and weakly interacting subatomic particles with ½ unit of spin. Also antineutrinos (as neutrinos) are very penetrating subatomic particles, capable of passing through Earth without any interaction. Currently (2015), it is not resolved, whether the neutrino and its antiparticle are not identical particles.

Antineutrinos are produced in the negative beta decay. In a nuclear reactor occurs especially the β⁻ decay, because the common feature of the fission products is an excess of neutrons (see Nuclear Stability). An unstable fission fragment with the excess of neutrons undergoes β⁻ decay, where the neutron is converted into a proton, an electron, and an electron antineutrino. Therefore each nuclear reactor is very powerful source of antineutrinos and researchers around the world investigate the possibilities of using antineutrinos for reactor monitoring.

On the other hand the most powerful source of neutrinos in the solar system is doubtless the Sun itself. Billions of solar neutrinos per second pass (mostly without any interaction) through every square centimeter (~6 x 10¹⁰ cm^-2s^-1) on the Earth’s surface. In the Sun, neutrinos are produced after fusion reaction of two protons during positive beta decay of helium-2 nucleus.

$_{2}^{2}textrm{He}rightarrow _{1}^{2}textrm{H} + beta^{+} + nu_{{e}}$

Detection of Antineutrinos

Since neutrinos do not ionize matter, they cannot be detected directly. The antineutrino detection (1995 Nobel Prize for Frederick Reines and Clyde Cowan) is based on the reaction:

Nuclear Reactor as the Antineutrino Source

Nuclear reactors are the major source of human-generated antineutrinos. This is due to the fact that antineutrinos are produced in a negative beta decay. In a nuclear reactor occurs especially the β⁻ decay, because the common feature of the fission fragments is an excess of neutrons (see Nuclear Stability). An unstable fission fragment with the excess of neutrons undergoes β⁻ decay, where the neutron is converted into a proton, an electron, and an electron antineutrino. The existence of emission of antineutrinos and their very low cross-section for any interaction leads to very interesting phenomenon. Roughly about 5% (or about 12 MeV of 207 MeV) of released energy per one fission is radiated away from reactor in the form of antineutrinos. For a typical nuclear reactor with a thermal power of 3000 MW_th (~1000MW_e of electrical power), the total power produced is in fact higher, approximately 3150 MW, of which 150 MW is radiated away into space as antineutrino radiation. This amount of energy is forever lost, since antineutrinos are able to penetrate all reactor materials without any interaction. In fact, a common statement in physics texts is that the mean free path of a neutrino is approximately a light-year of lead. Moreover, a neutrino of moderate energy can easily penetrate a thousand light-years of lead (according to the J. B. Griffiths).

Please note that billions of solar neutrinos per second pass (mostly without any interaction) through every square centimeter (~6×10¹⁰) on the Earth’s surface and antineutrino radiation is by no means dangerous.

Example – Amount of antineutrinos produced:

Stable nuclei with most likely mass number A from U-235 fission are $_{40}^{94}textrm{Zr}$ and $_{58}^{140}textrm{Ce}$ . These nuclei have together 98 protons and 136 neutrons, while fission fragments (parent nuclei) have together 92 protons and 142 neutrons. This means after each U-235 fission the fission fragments must undergo on average 6 negative beta decays (6 neutrons must decay to 6 protons) and therefore 6 antineutrinos must be produced per each fission. The typical nuclear reactor therefore produces approximately 6 x 10²⁰ antineutrinos per second (~200 MeV/fission; ~6 antineutrinos/fission; 3000 MW_th; 9.375 x 10¹⁹ fissions/sec).

Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987.

beta decay — Beta decay of C-14 nucleus.

Fission fragment yields — Fission fragment yield for different nuclei. The most probable fragment masses are around mass 95 (Krypton) and 137 (Barium).

What is Neutrino – Definition

December 14, 2019 by Nick Connor

A neutrino is an elementary subatomic particle with infinitesimal mass and with no electric charge. Neutrinos are weakly interacting subatomic particles with ½ unit of spin. Radiation Dosimetry

A neutrino is an elementary subatomic particle with infinitesimal mass (less than 0.3 eV..?) and with no electric charge. Neutrinos belong to the family of leptons, which means they do not interact via strong nuclear force. Neutrinos are weakly interacting subatomic particles with ½ unit of spin. The term neutrino comes from Italian meaning “little neutral one” and neutrinos are denoted by the Greek letter ν (nu). There are three types of charged leptons, each associated with neutrino, forming three generations (between generations, particle differ by their quantum number and mass). The first generation consist of the electron (e⁻) and electron-neutrino (ν_e). The second generation consist of the muon (μ⁻) and muon neutrino (ν_μ) The third generation consist of the tau (τ⁻) and the tau neutrino (ν_τ). Each type of neutrino is associated with an antimatter particle, called an antineutrino, which also has neutral electric charge and 1/2 spin. Currently (2015), it is not resolved, whether the neutrino and its antiparticle are not identical particles.

Carrying no electric charge they are not affected by electromagnetic forces that act on another charged leptons, such as electrons. Since neutrinos belong to the family of leptons, they are not subject to the strong force. Neutrinos are subject to the weak force, which is of much shorter range than electromagnetic force and gravity force. Therefore, neutrinos are the most penetrating subatomic particles, capable of passing through Earth without any interaction. It is estimated neutrinos have interaction cross-sections about 20 orders of magnitude less than typical cross-sections of scattering of two nucleons (~10^-47m2 = 10^-19barn). It is estimated neutrino cross-section for interaction increases linearly with energy of incident neutrino.

Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987.

Production of Neutrinos

Neutrinos can be produced in several ways. The most powerful source of neutrinos in the solar system is doubtless the Sun itself. Billions of solar neutrinos per second pass (mostly without any interaction) through every square centimeter (~6 x 10¹⁰ cm^-2s^-1) on the Earth’s surface. In the Sun, neutrinos are produced after fusion reaction of two protons during positive beta decay of helium-2 nucleus.

$_{2}^{2}textrm{He}rightarrow _{1}^{2}textrm{H} + beta^{+} + nu_{{e}}$

Each nuclear reactor is also very powerful source of neutrinos. In fact, antineutrinos. In a nuclear reactor occurs especially the β⁻ decay, because the common feature of the fission products is an excess of neutrons (see Nuclear Stability). An unstable fission fragment with the excess of neutrons undergoes β⁻ decay, where the neutron is converted into a proton, an electron, and an electron antineutrino.

Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987.

What is Mass Attenuation Coefficient – Definition

December 14, 2019 by Nick Connor

The mass attenuation coefficient is defined as the ratio of the linear attenuation coefficient and absorber density (μ/ρ). Radiation Dosimetry

Mass Attenuation Coefficient

When characterizing an absorbing material, we can use sometimes the mass attenuation coefficient. The mass attenuation coefficient is defined as the ratio of the linear attenuation coefficient and absorber density (μ/ρ). The attenuation of gamma radiation can be then described by the following equation:

I=I₀.e^-(μ/ρ).ρl

, where ρ is the material density, (μ/ρ) is the mass attenuation coefficient and ρ.l is the mass thickness. The measurement unit used for the mass attenuation coefficient cm²g^-1.For intermediate energies the Compton scattering dominates and different absorbers have approximately equal mass attenuation coefficients. This is due to the fact that cross section of Compton scattering is proportional to the Z (atomic number) and therefore the coefficient is proportional to the material density ρ. At small values of gamma ray energy or at high values of gamma ray energy, where the coefficient is proportional to higher powers of the atomic number Z (for photoelectric effect σ_f ~ Z⁵; for pair production σ_p ~ Z²), the attenuation coefficient μ is not a constant.

What is Half Value Layer – Definition

December 14, 2019 by Nick Connor

The half value layer expresses the thickness of absorbing material needed for reduction of the incident radiation intensity by a factor of two. Radiation Dosimetry

Half Value Layer

The half value layer expresses the thickness of absorbing material needed for reduction of the incident radiation intensity by a factor of two. There are two main features of the half value layer:

The half value layer decreases as the atomic number of the absorber increases. For example 35 m of air is needed to reduce the intensity of a 100 keV gamma ray beam by a factor of two whereas just 0.12 mm of lead can do the same thing.
The half value layer for all materials increases with the energy of the gamma rays. For example from 0.26 cm for iron at 100 keV to about 1.06 cm at 500 keV.

The half value layer expresses the thickness of absorbing material needed for reduction of the incident radiation intensity by a factor of two. With half value layer it is easy to perform simple calculations.
Source: www.nde-ed.org

Table of Half Value Layers (in cm) for a different materials at gamma ray energies of 100, 200 and 500 keV.

Absorber	100 keV	200 keV	500 keV
Air	3555 cm	4359 cm	6189 cm
Water	4.15 cm	5.1 cm	7.15 cm
Carbon	2.07 cm	2.53 cm	3.54 cm
Aluminium	1.59 cm	2.14 cm	3.05 cm
Iron	0.26 cm	0.64 cm	1.06 cm
Copper	0.18 cm	0.53 cm	0.95 cm
Lead	0.012 cm	0.068 cm	0.42 cm

What is Linear Attenuation Coefficient – Definition

December 14, 2019 by Nick Connor

The sum of the three partial cross-sections is called the linear attenuation coefficient. Gamma rays attenuation. Radiation Dosimetry

The total cross-section of interaction of a gamma rays with an atom is equal to the sum of all three mentioned partial cross-sections:σ = σ_f + σ_C + σ_p

σ_f – Photoelectric effect

σ_C – Compton scattering

σ_p – Pair production

Depending on the gamma ray energy and the absorber material, one of the three partial cross-sections may become much larger than the other two. At small values of gamma ray energy the photoelectric effect dominates. Compton scattering dominates at intermediate energies. The compton scattering also increases with decreasing atomic number of matter, therefore the interval of domination is wider for light nuclei. Finally, electron-positron pair production dominates at high energies.Based on the definition of interaction cross-section, the dependence of gamma rays intensity on thickness of absorber material can be derive. If monoenergetic gamma rays are collimated into a narrow beam and if the detector behind the material only detects the gamma rays that passed through that material without any kind of interaction with this material, then the dependence should be simple exponential attenuation of gamma rays. Each of these interactions removes the photon from the beam either by absorbtion or by scattering away from the detector direction. Therefore the interactions can be characterized by a fixed probability of occurance per unit path length in the absorber. The sum of these probabilities is called the linear attenuation coefficient:

μ = τ_{(photoelectric)} + σ_(Compton) + κ_(pair)

Linear Attenuation Coefficient

The attenuation of gamma radiation can be then described by the following equation.

I=I₀.e^-μx

, where I is intensity after attenuation, I_o is incident intensity, μ is the linear attenuation coefficient (cm^-1), and physical thickness of absorber (cm).

The materials listed in the table beside are air, water and a different elements from carbon (Z=6) through to lead (Z=82) and their linear attenuation coefficients are given for three gamma ray energies. There are two main features of the linear attenuation coefficient:

The linear attenuation coefficient increases as the atomic number of the absorber increases.
The linear attenuation coefficient for all materials decreases with the energy of the gamma rays.

Dependence of gamma radiation intensity on absorber thickness.

The relative importance of various processes of gamma radiation interaction with matter.Linear Attenuation CoefficientsTable of Linear Attenuation Coefficients (in cm-1) for a different materials at gamma ray energies of 100, 200 and 500 keV.

Absorber	100 keV	200 keV	500 keV
Air	0.000195/cm	0.000159/cm	0.000112/cm
Water	0.167/cm	0.136/cm	0.097/cm
Carbon	0.335/cm	0.274/cm	0.196/cm
Aluminium	0.435/cm	0.324/cm	0.227/cm
Iron	2.72/cm	1.09/cm	0.655/cm
Copper	3.8/cm	1.309/cm	0.73/cm
Lead	59.7/cm	10.15/cm	1.64/cm

What is Inverse Compton Scattering – Definition

December 14, 2019 by Nick Connor

Inverse Compton scattering is the scattering of low energy photons to high energies by relativistic electrons. Radiation Dosimetry

Compton Scattering

Inverse Compton Scattering

Inverse Compton scattering is the scattering of low energy photons to high energies by relativistic electrons. Relativistic electrons can boost energy of low energy photons by a potentially enormous amount (even gamma rays can be produced). This phenomenon is very important in astrophysics.

What is Compton Edge – Definition

December 14, 2019 by Nick Connor

In spectrophotometry, the Compton edge is a feature of the spectrograph that results from the Compton scattering in the scintillator or detector. Radiation Dosimetry

Compton Scattering

Compton Edge

In spectrophotometry, the Compton edge is a feature of the spectrograph that results from the Compton scattering in the scintillator or detector. This feature is due to photons that undergo Compton scattering with a scattering angle of 180° and then escape the detector. When a gamma ray scatters off the detector and escapes, only a fraction of its initial energy can be deposited in the sensitive layer of the detector. It depends on the scattering angle of the photon, how much energy will be deposited in the detector. This leads to a spectrum of energies. The Compton edge energy corresponds to full backscattered photon.

What is Cross-Section of Compton Scattering – Definition

December 14, 2019 by Nick Connor

The angular distribution (cross-sections) of photons scattered from a single free electron is described by the Klein-Nishina formula. Cross-Section of Compton Scattering

Compton Scattering

Compton Scattering – Cross-Sections

The probability of Compton scattering per one interaction with an atom increases linearly with atomic number Z, because it depends on the number of electrons, which are available for scattering in the target atom. The angular distribution of photons scattered from a single free electron is described by the Klein-Nishina formula:where ε = E₀/m_ec² and r₀ is the “classical radius of the electron” equal to about 2.8 x 10^-13 cm. The formula gives the probability of scattering a photon into the solid angle element dΩ = 2π sin Θ dΘ when the incident energy is E₀.

Compton scattering experiment — The wavelength change in such scattering depends only upon the angle of scattering for a given target particle.
Source: hyperphysics.phy-astr.gsu.edu/

Cross section of compton scattering of photons by atomic electrons..

Energies of a photon at 500 keV and an electron after Compton scattering.

Shielding of Radiation in Nuclear Power Plants

Shielding of Alpha Radiation

Shielding of Beta Radiation

Shielding of Positrons

Characteristics of Gamma Rays

Shielding of Gamma Radiation

Water as a neutron shield

Concrete as a neutron shield

Calculation of Shielded Dose Rate in Sieverts from Contaminated Surface

Buildup Factors for Gamma Rays Shielding

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Detection of Antineutrinos

Nuclear Reactor as the Antineutrino Source

Example – Amount of antineutrinos produced:

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Discovery of the Neutrino

Production of Neutrinos

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Mass Attenuation Coefficient

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Half Value Layer

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Linear Attenuation Coefficient

Compton Scattering

Inverse Compton Scattering

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Compton Scattering

Compton Edge

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Compton Scattering

Compton Scattering – Cross-Sections

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