Outline. Radiation Interactions. Spurs, Blobs and Short Tracks. Introduction. Radiation Interactions 1
|
|
- Maurice Carr
- 6 years ago
- Views:
Transcription
1 Outline Radiation Interactions Introduction Interaction of Heavy Charged Particles Interaction of Fast Electrons Interaction of Gamma Rays Interactions of Neutrons Radiation Exposure & Dose Sources of Radiation Exposure 2 Spurs, Blobs and Short Tracks Energy deposition occurs in discrete events at the nanometer level. Introduction These events are categorized as spurs, blobs, short tracks and branch tracks. The amount of energy deposited determines whether an event will cause a spur or a larger event. 4 Radiation Interactions 1
2 Spurs, Blobs and Short Tracks Remember: Secondary electrons that are emitted with high energy after a scattering event are called δ rays. They will create their own track. Spurs, Blobs and Short Tracks Blobs Spurs ev Primary <100 ev < 5000 ev >5000 ev Short Tracks -rays Branch Tracks (from Mozunder and Magee 1966) A 1 MeV electron will deposit about 65 % of its energy in isolated spurs, 15 % in blobs and 20 % in short tracks. 5 6 Entity Energy Deposition Events for Low LET Radiation Energy Deposited (ev) Size (nm) Number of Water Molecules Per Event Energy (%) Events (%) Spur <100 2 (diam.) 1100 ~80 95 Blob <500 7 (diam.) 6000 ~20 5 Short Track DNA 2 (diam.) Nucleosome disc 5.7 Thickn. 5.5 Radius Diameter of the area in which energy is deposited is similar to the diameter of DNA and nucleosomes. Spurs, Blobs and Short Tracks In a typical cell volume, a dose of 1 Gy will produce ~75,000 spurs and ~4,000 blobs. The energy deposited in these events is sufficient enough to cause several ionizations. Example: An energy of ~32 ev is needed to produce an ion pair in water. This means a 100 ev spur could contain 3 ion pairs. 7 8 Radiation Interactions 2
3 Charged vs. Uncharged Radiation The radiation produced by the radiation sources previously discussed can be grouped into: Charged Particulate Radiation (Directly Ionizing) Heavy charged Particles (Range ~ 10 5 m) Fast Electrons (Range ~ 10 3 m) Uncharged Radiation (Indirectly Ionizing) Neutrons (Range ~ 10 1 m) X Rays and Gamma Rays (Range ~ 10 1 m) Interactions Charged particulate radiations interact continuously with the electrons in any medium through which they pass. This interaction is due to the Coulomb force. The interactions result in excitations and ionizations. Uncharged radiations are not affected by coulomb forces. Instead they undergo a direct, catastrophic interaction. It radically alters the properties of the radiation Interactions This interaction results in the complete or partial transfer of energy to a secondary particle. This secondary particle is charged and causes ionization. Interaction of a photon produces an electron. Interaction of a neutron produces a heavy charged particle. Uncharged radiation will remain undetected if this catastrophic interaction does not occur within the detector volume. Interaction of Heavy Charged Particles 11 Radiation Interactions 3
4 Nature of the Interaction Nature of the Interaction Heavy charged particle interact primarily through Coulomb forces. These forces are due to the positive charge of the particle and the negative charge of the orbital electrons. Direct interaction with a nucleus is possible but occurs only very rarely. Such direct encounters are not significant for the response of a radiation detector. The charged particle interacts with many electrons simultaneously when it enters the medium. In each interaction energy is transferred from the particle to an electron Nature of the Interaction Stopping Power As the result of the interaction ion pairs are produced. Each pair consists of an electron and a positively charged atom. Typically these ion pairs recombine very quickly to form neutral atoms. They can however be separated and detected by introducing an electrical field. This is the basis for several types of radiation detectors. The linear stopping power S is defined as the differential energy loss per unit path length. de S dx (in MeV cm 1 ) Radiation Interactions 4
5 Stopping Power The classical expression for the stopping power is given by the Bethe formula: S 4 de 4 π e z 2 dx m v where 2 2 m0 v NZ ln I v ln 1 c v, z = velocity, charge of the primary particle NZ = Number of absorber electrons per cm 3 I = Mean ionization and absorbing potential v c Stopping Power Several important conclusions can be drawn from this equation: The stopping power varies with 1/v 2. The stopping power increases as the velocity decreases. The stopping power varies with z 2. Particles with the greatest charge will experience the highest energy loss Stopping Power Stopping Power For different materials the energy loss depends primarily on the product NZ. High atomic number, high density materials will have the greatest stopping power. 19 Variation of the specific energy loss in air versus energy of the charged particle shown. Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) 20 Radiation Interactions 5
6 Particle Range The range of heavy charged particles in matter is well defined. For small absorber thicknesses the only effect is an energy loss. Because the particle tracks through the absorber are quite straight, the total number of particles that reach the detector remains the same. No attenuation takes place until the thickness of the absorber approaches the length of the shortest track. Particle Range Increasing the thickness further stops more and more particles until the number drops rapidly to zero Particle Range Particle Range The mean range is defined as the absorber thickness that reduces the particle count to exactly half of its original value. This definition is most commonly used in numerical range tables. The extrapolated range is obtained by extrapolating the linear portion at the end to zero. Historically this type of experiment was used to determine the energy of alpha particles indirectly. An alpha particle transmission experiment. I is the detected number of alpha particles through an absorber thickness t, whereas I 0 is the number detected without the absorber. The mean range R m and the extrapolated range R e are indicated. 23 Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) 24 Radiation Interactions 6
7 Interaction of Fast Electrons Interaction of Fast Electrons Electrons lose their energy at a lower rate compared to heavy charged particles. The mass of the electron is the same as that of the orbital electrons with which it is interacting. A much larger fraction of its energy can be transferred in a single encounter. As a result the electron can experience large deviations from its path. Electrons do not take a straight path through the absorbing medium. 26 Specific Energy Loss Electrons can lose energy through collisions as well as through radiative processes, in particular Bremsstrahlung. The total linear stopping power for electrons is therefore composed of two components: de dx de dx c de dx r Absorption of Monoenergetic Electrons The energy losses through collision can be described by a modified Bethe formula. 27 Transmission curve for monoenergetic electrons. R e is the extrapolated range. Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) 28 Radiation Interactions 7
8 Absorption of Monoenergetic Electrons Even small absorber thicknesses lead to electron loss due to scattering. Therefore a plot of the number of detected electrons versus absorber thickness begins to drop immediately. It gradually approaches zero for large absorber thicknesses. The electrons that penetrate the greatest absorber thickness will be the ones whose initial direction has been changed the least. Range of Electrons in Matter The concept of range is less definite for electrons. This is because their total path length is much greater than their distance of penetration. The electron range can be obtained from a transmission plot by extrapolation of the linear portion of the curve to zero. The specific energy loss of electrons is much lower than that of heavy charged particles, so their path length is hundreds of times greater Absorption of Beta Particles Absorption of Beta Particles The transmission curve for beta particles differs from that for monoenergetic electrons because of their continuous energy distribution. The initial slope is much steeper due to the rapid absorption of low energy beta particles. For most beta spectra the curve has a near exponential shape. This is only an empirical approximation and does not have a fundamental base. 31 Transmission curves for beta particles from 185 W (endpoint energy of 0.43 MeV). Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) 32 Radiation Interactions 8
9 Backscattering The fact that electrons often undergo large angle deflection can lead to backscattering. This means an electron can be deflected enough to scatter out of a medium which it entered. Backscattering is most pronounced for electrons with low incident energy and absorbers with high Z. Backscattering can influence the efficiency of beta emitter measurements because the electrons are scattered by the source backing. Positron Interactions The major mechanism of energy loss for positrons is based on coulomb interactions. The impulse and energy transfer for particles of similar mass is the same, no matter whether the interaction involves a repulsive or attractive force. Therefore the tracks of positrons in an absorber are similar to those of electrons. The main difference however is the annihilation radiation emitted by positrons Interaction of Gamma Rays Interaction of Gamma Rays When a photon interacts with matter, its energy is either partially or completely transferred into electron energy. This means the photons disappears entirely or is scattered through a significant angle. This behavior is very different from charged particles, which slow down gradually through many interactions with absorber atoms. 36 Radiation Interactions 9
10 Interaction of Gamma Rays A large number of possible interaction mechanisms are known for gamma rays in matter. Only three major types play a role in radiation measurements: Photoelectric absorption Compton scattering Pair production Photoelectric Absorption In the photoelectric absorption process a photon transfers all of its energy to a bound electron. The photon disappears entirely and the electron is ejected as a photoelectron. This interaction is not possible with a free electron due to momentum conservation. The photoelectron appears with an energy: E hν E e b Photoelectric Absorption Photoelectric Scattering Process As a result of the photoelectron emission a vacancy in one of the bound shells is created. This vacancy is quickly filled by an electron from a higher shell. As a result one or more characteristic X rays may emitted. These X rays are generally reabsorbed close to the original site, but their migration and escape can influence the response of detectors. In some cases an Auger electron is emitted instead of the X ray. E=hν E=ΔB.E. 2. E=hν B.E Radiation Interactions 10
11 Photoelectric Absorption This process is the predominant interaction for gamma ray energies of less than a few hundred kev. It has a higher probability in high Z materials. The probability for photoelectric absorption scales as: Z τ cons E γ Compton Scattering Compton scattering is the predominant interaction mechanism for gamma rays energies typical of radioisotope sources. Scattering takes place between the incident gamma ray and a loosely bound or free electron in the absorbing material. The incoming photon transfers a portion of its energy to the electron. The photon itself is deflected at an angle Θ and the electron is emitted as a recoil electron Compton Scattering Process Compton Scattering E=hν E=hν hν B.E. The energy transferred depends on the scattering angle of the photon. The detailed derivation of this relationship can be found in the textbook. The scattering probability depends on the number of electrons available as scattering targets. It increases linearly with Z. Compton scattering is the most important energy loss mechanism for energies from a few hundred kev up to a few MeV. E=hν Radiation Interactions 11
12 Pair Production Pair production is possible if the energy of the gamma ray exceeds twice the rest mass of an electron (1.02 MeV). The gamma ray disappears and is replaced by an electron positron pair. The interaction must take place in the coulomb field of a nucleus. All photon energy in excess of 1.02 MeV is converted into kinetic energy shared between the electron and the positron. Pair Production The positron will subsequently slow down in the medium and annihilate with another electron, releasing two 511 kev photons in the process. The pair production probability remains very low until the gamma ray energy approaches several MeV. The magnitude of the probability varies approximately with Z 2 of the absorber, but no simple expression exits for this relation Interaction Type vs. Z and Energy Interaction of Neutrons The relative importance of the three major types of gamma ray interaction. The lines show the values of Z and hν for which the two neighboring effects are just equal. Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) 47 Radiation Interactions 12
13 General Properties Neutrons carry no charge and therefore can not interact by means of the coulomb force. If the neutron interacts at all, it interacts with the nucleus of the absorbing medium. As a result the neutron either disappears and is replaced by a secondary radiation, or its energy and direction is significantly changed. The secondary radiation is almost always a heavy charged particle. The probability of the various types of interaction depends on the neutron energy. Slow Neutron Interactions The significant interactions for slow neutrons are elastic scattering and neutron induced nuclear reactions. The kinetic energy of slow neutrons is very small, therefore only little energy is transferred in the scattering. Consequently, this interaction can not be used to detect slow neutrons. The most important interactions are neutron induced reaction. These allow for the detection of the secondary radiation emitted Fast Neutron Interactions The probability of the most useful neutron induced reactions drops off with increasing neutron energy. Scattering however becomes more important, because more energy can be transferred, resulting in recoil nuclei being emitted. At sufficiently high energies inelastic scattering can take place. In this case the recoil nucleus becomes excited and deexcites by emission of a gamma ray. Neutron Cross Sections For fixed energy neutrons the probability per unit path length is constant for each interaction type. This probability is generally expressed in terms of the cross section σ per nucleus. The cross section has the units of an area and is traditionally measured in barn (10 24 cm 2 ). Multiplying the cross section by the number of nuclei N per unit volume gives the macroscopic cross section Σ. N σ Σ Radiation Interactions 13
14 Neutron Cross Sections Σ can be interpreted as the interaction probability per unit path length (length 1 ). Each type of interaction has a specific cross section. The total cross section can be obtained by adding up the individual cross sections. Σ tot Σ scatter Σ rad.capture... This quantity has the same significance for neutrons as the linear attenuation coefficient for gamma rays. Neutron Cross Sections The results of a narrow beam attenuation will follow: where I I 0 e Σtot t t = Distance the neutron travels The neutron reaction rate density reactions per volume per time is defined as ΣΦ. Φ is called the neutron flux and has the unit length 2 time Gamma Ray Exposure Radiation Exposure & Dose The concept of gamma ray exposure was introduced early in the history of radioisotope research. It is defined only for sources of X and gamma rays. The exposure is defined as the charge dq due to ionization from secondary electrons in a volume element of air with mass dm. The exposure value X is given by dq/dm. The SI unit of gamma ray exposure is C kg Radiation Interactions 14
15 Gamma Ray Exposure The historical unit has been the roentgen (R). It is defined as the amount of exposure that produces 1 electrostatic unit of charge per 1 cm 3. 1 R = 2.58 x 10 4 C/kg. Gamma Ray Exposure The gamma ray exposure at a known distance d from a spherical sources with an activity α can be calculated as: α X Γ δ d 2 Γ δ is given in units of (R cm 2 )/(hr mci) Absorbed Dose Two different materials will in general absorb different amounts if subjected to the same gamma ray exposure. Many important phenomena scale with the amount of energy absorbed per unit mass. Therefore a unit is needed that measures this quantity. The energy absorbed from any type of radiation per unit mass of absorber is defined as the absorbed dose. Absorbed Dose The SI unit of absorbed dose is the Gray (Gy). It is defined as 1 J kg 1. The historical unit of absorbed dose has been the rad. It is defined as 100 ergs / g. 100 rad equal 1 Gy. An absorbed dose in air of 33.8 Gy corresponds to a gamma ray exposure of 1 C kg Radiation Interactions 15
16 Dose Equivalent The absorption of equal amounts of energy per mass does not guarantee the same biological effect for different types of radiation. The extend of biological damage can vary by as much as an order of magnitude depending on whether the energy is deposited by heavy charged particles or by electrons. The severity and permanence of biological effects is directly related to the local rate of energy deposition along the particle track. Dose Equivalent This quantity is know as the linear energy transfer, L. Radiations with a large L value tend to result in greater biological damage than those with lower values for L. To quantify the biological effects better, the concept of dose equivalent has been introduced. A unit of dose equivalent is defined as the amount of any type of radiation that results in the same biological effect as one unit of dose delivered in the form of low LET radiation Dose Equivalent The dose equivalent H is the product of the absorbed dose D and the quality factor Q. Dose Equivalent The quality factor increases with linear energy transfer L. H D Q Source: Knoll, G. F., Radiation Detection and Measurement, 4 th Edition, John Wiley (2010) Radiation Interactions 16
17 Dose Equivalent All fast electron radiations of interest have a quality factor of 1 because L is sufficiently low. The same is true for X and gamma rays. The quality factor is much higher for charged particles and neutrons. Units of Dose Equivalent The unit of H depends on the corresponding unit of the absorbed dose D. If D is expressed in Gy, then H is defined in units of Sievert (Sv). If D is expressed in rad, then H is defined in units of rem. 1 Sv = 100 rem Categories of Exposure Sources Sources of Radiation Exposure The sources of radiation exposure to the general population can be divided in five broad categories: 1. Exposure from ubiquitous background radiation, including radon in homes. 2. Exposure to patients from medical procedures. 3. Exposure from consumer products or activities involving radiation sources. 4. Exposure from industrial, security, medical, educational and research radiation sources. 5. Exposure of workers that results from their occupations. 68 Radiation Interactions 17
18 Presentation of Results The exposure is presented as annual values for: 1. Collective effective dose (S) (person sievert) This is the cumulative dose to a population of individuals exposed to a given radiation source or group of sources. 2. Effective dose per individual in the U.S. population (E US ) (millisievert) Obtained by dividing S by the total number of individuals in the U.S. population whether exposed to the specific source or not. Presentation of Results 3. Average effective dose to an individual in a group exposed to a specific source (E Exp ) (millisievert). This excludes individuals that are not subject to exposure from the specific source of radiation Sources of Radiation Exposure (1982) Sources of Radiation Exposure (1982) Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 93 (1987) 71 Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 93 (1987) 72 Radiation Interactions 18
19 Effective Dose per Individual in the U.S. Population (1982) Effective Dose per Individual in the U.S. Population (1982) Source S (person Sv) E US (msv) E Exp (msv) Ubiquitous background 690, Radon & Thoron 460, Space 65, Internal 90, Terrestrial 65, Medical 123, Source S (person Sv) E US (msv) E Exp (msv) Consumer 29, Miscellaneous Nuclear Fuel Cycle Occupational 2, Total 835, Diagnostic X rays 91, Nuclear Medicine 32, Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 93 (1987) 73 Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 93 (1987) 74 Sources of Radiation Exposure (2006) Sources of Radiation Exposure (2006) Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 160 (2009) 75 Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 160 (2009) 76 Radiation Interactions 19
20 Sources of Radiation Exposure (2006) Effective Dose per Individual in the U.S. Population (2006) Source S (person Sv) E US (msv) E Exp (msv) Ubiquitous background 933, Radon & Thoron 684, Space 99, Internal 87, Terrestrial 63, Medical 899, CT 440, Nuclear Medicine 231, Interventional Fluoroscopy 128, Radiography & Fluoroscopy 100, Consumer 39, Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 160 (2009) 77 Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 160 (2009) 78 Effective Dose per Individual in the U.S. Population (2006) Source S (person Sv) E US (msv) E Exp (msv) Industrial 1, Occupational 1, Medical Aviation Commercial Nuclear Power Industry & Commerce Education & Research Government, DOE,Military Total 1,870, Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report 160 (2009) 79 Radiation Interactions 20
CHARGED PARTICLE INTERACTIONS
CHARGED PARTICLE INTERACTIONS Background Charged Particles Heavy charged particles Charged particles with Mass > m e α, proton, deuteron, heavy ion (e.g., C +, Fe + ), fission fragment, muon, etc. α is
More informationIII. Energy Deposition in the Detector and Spectrum Formation
1 III. Energy Deposition in the Detector and Spectrum Formation a) charged particles Bethe-Bloch formula de 4πq 4 z2 e 2m v = NZ ( ) dx m v ln ln 1 0 2 β β I 0 2 2 2 z, v: atomic number and velocity of
More informationChapter Four (Interaction of Radiation with Matter)
Al-Mustansiriyah University College of Science Physics Department Fourth Grade Nuclear Physics Dr. Ali A. Ridha Chapter Four (Interaction of Radiation with Matter) Different types of radiation interact
More informationInteraction of Ionizing Radiation with Matter
Type of radiation charged particles photonen neutronen Uncharged particles Charged particles electrons (β - ) He 2+ (α), H + (p) D + (d) Recoil nuclides Fission fragments Interaction of ionizing radiation
More informationRadiation Detection for the Beta- Delayed Alpha and Gamma Decay of 20 Na. Ellen Simmons
Radiation Detection for the Beta- Delayed Alpha and Gamma Decay of 20 Na Ellen Simmons 1 Contents Introduction Review of the Types of Radiation Charged Particle Radiation Detection Review of Semiconductor
More informationPhysics of Radiotherapy. Lecture II: Interaction of Ionizing Radiation With Matter
Physics of Radiotherapy Lecture II: Interaction of Ionizing Radiation With Matter Charge Particle Interaction Energetic charged particles interact with matter by electrical forces and lose kinetic energy
More informationInteraction of charged particles and photons with matter
Interaction of charged particles and photons with matter Robert Miyaoka, Ph.D. Old Fisheries Center, Room 200 rmiyaoka@u.washington.edu Passage of radiation through matter depends on Type of radiation
More informationLECTURE 4 PRINCIPLE OF IMAGE FORMATION KAMARUL AMIN BIN ABDULLAH
LECTURE 4 PRINCIPLE OF IMAGE FORMATION KAMARUL AMIN BIN ABDULLAH Lesson Objectives At the end of the lesson, student should able to: Define attenuation Explain interactions between x-rays and matter in
More informationRadiation Quantities and Units
Radiation Quantities and Units George Starkschall, Ph.D. Lecture Objectives Define and identify units for the following: Exposure Kerma Absorbed dose Dose equivalent Relative biological effectiveness Activity
More information05/11/2013. Nuclear Fuel Cycle Ionizing radiation. Typical decay energies. Radiation with energy > 100 ev. Ionize an atom < 15eV
Nuclear Fuel Cycle 2013 Lecture 4: Interaction of Ionizing Radiation with Matter Ionizing radiation Radiation with energy > 100 ev Ionize an atom < 15eV Break a bond 1-5 ev Typical decay energies α: 4-9
More informationNeutron Interactions Part I. Rebecca M. Howell, Ph.D. Radiation Physics Y2.5321
Neutron Interactions Part I Rebecca M. Howell, Ph.D. Radiation Physics rhowell@mdanderson.org Y2.5321 Why do we as Medical Physicists care about neutrons? Neutrons in Radiation Therapy Neutron Therapy
More informationToday, I will present the first of two lectures on neutron interactions.
Today, I will present the first of two lectures on neutron interactions. I first need to acknowledge that these two lectures were based on lectures presented previously in Med Phys I by Dr Howell. 1 Before
More information11/23/2014 RADIATION AND DOSE MEASUREMENTS. Units of Radioactivity
CHAPTER 4 RADIATION UNITS RADIATION AND DOSE MEASUREMENTS 1 Units of Radioactivity 2 1 Radiation Units There are specific units for the amount of radiation you receive in a given time and for the total
More informationBasic physics Questions
Chapter1 Basic physics Questions S. Ilyas 1. Which of the following statements regarding protons are correct? a. They have a negative charge b. They are equal to the number of electrons in a non-ionized
More informationOutline. Chapter 6 The Basic Interactions between Photons and Charged Particles with Matter. Photon interactions. Photoelectric effect
Chapter 6 The Basic Interactions between Photons and Charged Particles with Matter Radiation Dosimetry I Text: H.E Johns and J.R. Cunningham, The physics of radiology, 4 th ed. http://www.utoledo.edu/med/depts/radther
More informationINTERACTIONS OF RADIATION WITH MATTER
INTERACTIONS OF RADIATION WITH MATTER Renée Dickinson, MS, DABR Medical Physicist University of Washington Medical Center Department of Radiology Diagnostic Physics Section Outline Describe the various
More informationCHAPTER 2 RADIATION INTERACTIONS WITH MATTER HDR 112 RADIATION BIOLOGY AND RADIATION PROTECTION MR KAMARUL AMIN BIN ABDULLAH
HDR 112 RADIATION BIOLOGY AND RADIATION PROTECTION CHAPTER 2 RADIATION INTERACTIONS WITH MATTER PREPARED BY: MR KAMARUL AMIN BIN ABDULLAH SCHOOL OF MEDICAL IMAGING FACULTY OF HEALTH SCIENCE Interactions
More informationPossible Interactions. Possible Interactions. X-ray Interaction (Part I) Possible Interactions. Possible Interactions. section
Possible Interactions X-ray Interaction (Part I) Three types of interaction 1. Scattering Interaction with an atom Deflected May or may not loss of energy 1 Possible Interactions Three types of interaction
More informationEEE4101F / EEE4103F Radiation Interactions & Detection
EEE4101F / EEE4103F Radiation Interactions & Detection 1. Interaction of Radiation with Matter Dr. Steve Peterson 5.14 RW James Department of Physics University of Cape Town steve.peterson@uct.ac.za March
More informationNuclear Spectroscopy: Radioactivity and Half Life
Particle and Spectroscopy: and Half Life 02/08/2018 My Office Hours: Thursday 1:00-3:00 PM 212 Keen Building Outline 1 2 3 4 5 Some nuclei are unstable and decay spontaneously into two or more particles.
More informationInteraction of Particles and Matter
MORE CHAPTER 11, #7 Interaction of Particles and Matter In this More section we will discuss briefly the main interactions of charged particles, neutrons, and photons with matter. Understanding these interactions
More informationLET! (de / dx) 1 Gy= 1 J/kG 1Gy=100 rad. m(kg) dose rate
Basics of Radiation Dosimetry for the Physicist http://en.wikipedia.org/wiki/ionizing_radiation I. Ionizing radiation consists of subatomic particles or electromagnetic waves that ionize electrons along
More informationChapter NP-4. Nuclear Physics. Particle Behavior/ Gamma Interactions TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 IONIZATION
Chapter NP-4 Nuclear Physics Particle Behavior/ Gamma Interactions TABLE OF CONTENTS INTRODUCTION OBJECTIVES 1.0 IONIZATION 2.0 ALPHA PARTICLE INTERACTIONS 3.0 BETA INTERACTIONS 4.0 GAMMA INTERACTIONS
More informationGy can be used for any type of radiation. Gy does not describe the biological effects of the different radiations.
Absorbed Dose Dose is a measure of the amount of energy from an ionizing radiation deposited in a mass of some material. SI unit used to measure absorbed dose is the gray (Gy). 1J 1 Gy kg Gy can be used
More informationGLOSSARY OF BASIC RADIATION PROTECTION TERMINOLOGY
GLOSSARY OF BASIC RADIATION PROTECTION TERMINOLOGY ABSORBED DOSE: The amount of energy absorbed, as a result of radiation passing through a material, per unit mass of material. Measured in rads (1 rad
More informationThe interaction of radiation with matter
Basic Detection Techniques 2009-2010 http://www.astro.rug.nl/~peletier/detectiontechniques.html Detection of energetic particles and gamma rays The interaction of radiation with matter Peter Dendooven
More informationEmphasis on what happens to emitted particle (if no nuclear reaction and MEDIUM (i.e., atomic effects)
LECTURE 5: INTERACTION OF RADIATION WITH MATTER All radiation is detected through its interaction with matter! INTRODUCTION: What happens when radiation passes through matter? Emphasis on what happens
More informationPhysics of Radiography
EL-GY 6813 / BE-GY 6203 / G16.4426 Medical Imaging Physics of Radiography Jonathan Mamou and Yao Wang Polytechnic School of Engineering New York University, Brooklyn, NY 11201 Based on Prince and Links,
More informationInteractions with Matter Photons, Electrons and Neutrons
Interactions with Matter Photons, Electrons and Neutrons Ionizing Interactions Jason Matney, MS, PhD Interactions of Ionizing Radiation 1. Photon Interactions Indirectly Ionizing 2. Charge Particle Interactions
More informationEEE4106Z Radiation Interactions & Detection
EEE4106Z Radiation Interactions & Detection 2. Radiation Detection Dr. Steve Peterson 5.14 RW James Department of Physics University of Cape Town steve.peterson@uct.ac.za May 06, 2015 EEE4106Z :: Radiation
More informationPhysics of Particle Beams. Hsiao-Ming Lu, Ph.D., Jay Flanz, Ph.D., Harald Paganetti, Ph.D. Massachusetts General Hospital Harvard Medical School
Physics of Particle Beams Hsiao-Ming Lu, Ph.D., Jay Flanz, Ph.D., Harald Paganetti, Ph.D. Massachusetts General Hospital Harvard Medical School PTCOG 53 Education Session, Shanghai, 2014 Dose External
More informationX-ray Interaction with Matter
X-ray Interaction with Matter 10-526-197 Rhodes Module 2 Interaction with Matter kv & mas Peak kilovoltage (kvp) controls Quality, or penetrating power, Limited effects on quantity or number of photons
More informationZX or X-A where X is chemical symbol of element. common unit: [unified mass unit = u] also known as [atomic mass unit = amu] or [Dalton = Da]
1 Part 5: Nuclear Physics 5.1. The Nucleus = atomic number = number of protons N = neutron number = number of neutrons = mass number = + N Representations: X or X- where X is chemical symbol of element
More informationINTRODUCTION TO IONIZING RADIATION (Attix Chapter 1 p. 1-5)
INTRODUCTION TO IONIZING RADIATION (Attix Chapter 1 p. 1-5) Ionizing radiation: Particle or electromagnetic radiation that is capable of ionizing matter. IR interacts through different types of collision
More informationIntroduction to Ionizing Radiation
Introduction to Ionizing Radiation Bob Curtis OSHA Salt Lake Technical Center Supplement to Lecture Outline V. 10.02 Basic Model of a Neutral Atom Electrons(-) orbiting nucleus of protons(+) and neutrons.
More informationWHAT IS IONIZING RADIATION
WHAT IS IONIZING RADIATION Margarita Saraví National Atomic Energy Commission - Argentina Workshop on Ionizing Radiation SIM Buenos Aires 10 November 2011 What is ionizing radiation? What is ionizing radiation?
More informationINTERACTION OF RADIATION WITH MATTER RCT STUDY GUIDE Identify the definitions of the following terms:
LEARNING OBJECTIVES: 1.07.01 Identify the definitions of the following terms: a. ionization b. excitation c. bremsstrahlung 1.07.02 Identify the definitions of the following terms: a. specific ionization
More information11/19/2014. Chapter 3: Interaction of Radiation with Matter in Radiology and Nuclear Medicine. Nuclide Families. Family Nuclides with Same: Example
2014-2015 Residents' Core Physics Lectures Mondays 7:00-8:00 am in VA Radiology and UCSDMC Lasser Conference Rooms Topic Chapters Date Faculty 1 Introduction and Basic Physics 1, 2 M 11/17 Andre 2 Interaction
More informationDOE-HDBK Radiological Control Technician Interaction of Radiation with Matter Module Number: 1.07
Course Title: Radiological Control Technician Module Title: Interaction of Radiation with Matter Module Number: 1.07 Objectives: 1.07.01 Identify the definitions of the following terms: a. ionization b.
More informationShielding of Ionising Radiation with the Dosimetry & Shielding Module
Shielding of Ionising Radiation with the Dosimetry & Shielding Module J. Magill Overview Biological Effects of Ionising Radiation - Absorber dose, Quality or Weighting Factor, Equivalent Dose Attenuation
More informationPhysics of Radiography
Physics of Radiography Yao Wang Polytechnic Institute of NYU Brooklyn, NY 11201 Based on J L Prince and J M Links Medical Imaging Signals and Based on J. L. Prince and J. M. Links, Medical Imaging Signals
More informationInteractions of Radiation with Matter
Main points from last week's lecture: Decay of Radioactivity Mathematics description nly yields probabilities and averages Interactions of Radiation with Matter William Hunter, PhD" Decay equation: N(t)
More informationSome nuclei are unstable Become stable by ejecting excess energy and often a particle in the process Types of radiation particle - particle
Radioactivity George Starkschall, Ph.D. Lecture Objectives Identify methods for making radioactive isotopes Recognize the various types of radioactive decay Interpret an energy level diagram for radioactive
More informationDecay Mechanisms. The laws of conservation of charge and of nucleons require that for alpha decay, He + Q 3.1
Decay Mechanisms 1. Alpha Decay An alpha particle is a helium-4 nucleus. This is a very stable entity and alpha emission was, historically, the first decay process to be studied in detail. Almost all naturally
More informationRadiation Physics PHYS /251. Prof. Gocha Khelashvili
Radiation Physics PHYS 571-051/251 Prof. Gocha Khelashvili Interaction of Radiation with Matter: Heavy Charged Particles Directly and Indirectly Ionizing Radiation Classification of Indirectly Ionizing
More informationNuclear Fusion and Radiation
Nuclear Fusion and Radiation Lecture 9 (Meetings 23 & 24) Eugenio Schuster schuster@lehigh.edu Mechanical Engineering and Mechanics Lehigh University Nuclear Fusion and Radiation p. 1/42 Radiation Interactions
More informationUnits and Definition
RADIATION SOURCES Units and Definition Activity (Radioactivity) Definition Activity: Rate of decay (transformation or disintegration) is described by its activity Activity = number of atoms that decay
More information3 Radioactivity - Spontaneous Nuclear Processes
3 Radioactivity - Spontaneous Nuclear Processes Becquerel was the first to detect radioactivity. In 1896 he was carrying out experiments with fluorescent salts (which contained uranium) and found that
More informationFor the next several lectures, we will be looking at specific photon interactions with matter. In today s lecture, we begin with the photoelectric
For the next several lectures, we will be looking at specific photon interactions with matter. In today s lecture, we begin with the photoelectric effect. 1 The objectives of today s lecture are to identify
More information4.1b - Cavity Theory Lecture 2 Peter R Al mond 2011 Overview of Lecture Exposure (W/e)air Exposure Exposure and and and Air Air Kerma
4.1b - Cavity Theory Lecture 2 Peter R Almond 2011 Overview of Lecture Exposure (W/e) air Exposure and Air Kerma Exposure Exposure is symbolized as X and defined by the ICRU as the quotient of dq by dm,
More informationRad T 290 Worksheet 2
Class: Date: Rad T 290 Worksheet 2 1. Projectile electrons travel from a. anode to cathode. c. target to patient. b. cathode to anode. d. inner shell to outer shell. 2. At the target, the projectile electrons
More informationRadiation Dose, Biology & Risk
ENGG 167 MEDICAL IMAGING Lecture 2: Sept. 27 Radiation Dosimetry & Risk References: The Essential Physics of Medical Imaging, Bushberg et al, 2 nd ed. Radiation Detection and Measurement, Knoll, 2 nd Ed.
More informationForms of Ionizing Radiation
Beta Radiation 1 Forms of Ionizing Radiation Interaction of Radiation with Matter Ionizing radiation is categorized by the nature of the particles or electromagnetic waves that create the ionizing effect.
More informationChapter 29. Nuclear Physics
Chapter 29 Nuclear Physics Ernest Rutherford 1871 1937 Discovery that atoms could be broken apart Studied radioactivity Nobel prize in 1908 Some Properties of Nuclei All nuclei are composed of protons
More informationRadiation Safety Talk. UC Santa Cruz Physics 133 Winter 2018
Radiation Safety Talk UC Santa Cruz Physics 133 Winter 2018 Outline Types of radiation Sources of radiation Dose limits and risks ALARA principle Safety procedures Types of radiation Radiation is energy
More informationINTRODUCTION TO MEDICAL PHYSICS 1 Quiz #1 Solutions October 6, 2017
INTRODUCTION TO MEDICAL PHYSICS 1 Quiz #1 Solutions October 6, 2017 This is a closed book examination. Adequate information is provided you to solve all problems. Be sure to show all work, as partial credit
More informationBasic physics of nuclear medicine
Basic physics of nuclear medicine Nuclear structure Atomic number (Z): the number of protons in a nucleus; defines the position of an element in the periodic table. Mass number (A) is the number of nucleons
More informationOutline. Absorbed Dose in Radioactive Media. Introduction. Radiation equilibrium. Charged-particle equilibrium
Absorbed Dose in Radioactive Media Chapter F.A. Attix, Introduction to Radiological Physics and Radiation Dosimetry Outline General dose calculation considerations, absorbed fraction Radioactive disintegration
More informationCollege Physics B - PHY2054C
College - PHY2054C Physics - Radioactivity 11/24/2014 My Office Hours: Tuesday 10:00 AM - Noon 206 Keen Building Review Question 1 Isotopes of an element A have the same number of protons and electrons,
More informationDetectors in Nuclear Physics (48 hours)
Detectors in Nuclear Physics (48 hours) Silvia Leoni, Silvia.Leoni@mi.infn.it http://www.mi.infn.it/~sleoni Complemetary material: Lectures Notes on γ-spectroscopy LAB http://www.mi.infn.it/~bracco Application
More informationModule 1. An Introduction to Radiation
Module 1 An Introduction to Radiation General Definition of Radiation Ionizing radiation, for example, X-rays, gamma-rays, α particles Ionizing radiation is capable of removing an electron from the atom
More informationInteraction of Radiation with Matter
Bose Institute Interaction of Radiation with Matter Dhruba Gupta Department of Physics Bose Institute, Kolkata Winter School on Astroparticle Physics (WAPP 011) December 0-9, 9, 011 at Mayapuri,, Darjeeling
More informationShell Atomic Model and Energy Levels
Shell Atomic Model and Energy Levels (higher energy, deeper excitation) - Radio waves: Not absorbed and pass through tissue un-attenuated - Microwaves : Energies of Photos enough to cause molecular rotation
More informationRadiation Protection Fundamentals and Biological Effects: Session 1
Radiation Protection Fundamentals and Biological Effects: Session 1 Reading assignment: LLE Radiological Controls Manual (LLEINST 6610): Part 1 UR Radiation Safety Training Manual and Resource Book: Parts
More informationAiro International Research Journal October, 2015 Volume VI, ISSN:
1 INTERACTION BETWEEN CHARGED PARTICLE AND MATTER Kamaljeet Singh NET Qualified Declaration of Author: I hereby declare that the content of this research paper has been truly made by me including the title
More informationCHEMISTRY Topic #1: Atomic Structure and Nuclear Chemistry Fall 2017 Dr. Susan Findlay See Exercises 2.3 to 2.6
CHEMISTRY 1000 Topic #1: Atomic Structure and Nuclear Chemistry Fall 2017 Dr. Susan Findlay See Exercises 2.3 to 2.6 Balancing Nuclear Reactions mass number (A) atomic number (Z) 12 6 C In an ordinary
More informationBa (Z = 56) W (Z = 74) preferred target Mo (Z = 42) Pb (Z = 82) Pd (Z = 64)
Produced by accelerating electrons with high voltage and allowing them to collide with metal target (anode), e.g, Tungsten. Three Events (Two types of x-ray) a) Heat X-Ray Tube b) bremsstrahlung (braking
More information2. Passage of Radiation Through Matter
2. Passage of Radiation Through Matter Passage of Radiation Through Matter: Contents Energy Loss of Heavy Charged Particles by Atomic Collision (addendum) Cherenkov Radiation Energy loss of Electrons and
More informationParticle Interactions in Detectors
Particle Interactions in Detectors Dr Peter R Hobson C.Phys M.Inst.P. Department of Electronic and Computer Engineering Brunel University, Uxbridge Peter.Hobson@brunel.ac.uk http://www.brunel.ac.uk/~eestprh/
More informationChapter V: Interactions of neutrons with matter
Chapter V: Interactions of neutrons with matter 1 Content of the chapter Introduction Interaction processes Interaction cross sections Moderation and neutrons path For more details see «Physique des Réacteurs
More informationRadiation Safety Training Session 1: Radiation Protection Fundamentals and Biological Effects
Radiation Safety Training Session 1: Radiation Protection Fundamentals and Biological Effects Reading Assignment: LLE Radiological Controls Manual (LLEINST 6610) Part 1 UR Radiation Safety Training Manual
More informationNuclear Physics and Astrophysics
Nuclear Physics and Astrophysics PHY-30 Dr. E. Rizvi Lecture 4 - Detectors Binding Energy Nuclear mass MN less than sum of nucleon masses Shows nucleus is a bound (lower energy) state for this configuration
More informationDR KAZI SAZZAD MANIR
DR KAZI SAZZAD MANIR PHOTON BEAM MATTER ENERGY TRANSFER IONISATION EXCITATION ATTENUATION removal of photons from the beam by the matter. ABSORPTION SCATTERING TRANSMISSION Taking up the energy from the
More informationCHAPTER 2 INTERACTION OF RADIATION WITH MATTER
CHAPTER 2 INTERACTION OF RADIATION WITH MATTER 2.1 Introduction When gamma radiation interacts with material, some of the radiation will be absorbed by the material. There are five mechanisms involve in
More informationInteraction theory Photons. Eirik Malinen
Interaction theory Photons Eirik Malinen Introduction Interaction theory Dosimetry Radiation source Ionizing radiation Atoms Ionizing radiation Matter - Photons - Charged particles - Neutrons Ionizing
More informationCHARGED PARTICLE INTERACTIONS
Physics Department, Yarmouk University, Irbid Jordan Dr. Nidal M. Ershaidat Phys. 649 Nuclear Instrumentation CHARGED PARTICLE INTERACTIONS Important note: This supplement is a re-edition of the published
More informationPhysics of particles. H. Paganetti PhD Massachusetts General Hospital & Harvard Medical School
Physics of particles H. Paganetti PhD Massachusetts General Hospital & Harvard Medical School Introduction Dose The ideal dose distribution ideal Dose: Energy deposited Energy/Mass Depth [J/kg] [Gy] Introduction
More information2015 Ph.D. Comprehensive Examination III. Radiological Sciences - Medical Physics
January 2015 2015 Ph.D. Comprehensive Examination III Radiological Sciences - Medical Physics In this three-hour exam, you are required to answer all of the questions in Part A and any two (2) out of the
More informationBASIC OF RADIATION; ORIGIN AND UNITS
INAYA MEDICAL COLLEGE (IMC) RAD 243 - LECTURE 2 BASIC OF RADIATION; ORIGIN AND UNITS DR. MOHAMMED MOSTAFA EMAM LECTURES & CLASS ACTIVITIES https://inayacollegedrmohammedemam.wordpress.com/ Password: drmohammedemam
More informationAt the conclusion of this lesson the trainee will be able to: a) Write a typical equation for the production of each type of radiation.
RADIOACTIVITY - SPONTANEOUS NUCLEAR PROCESSES OBJECTIVES At the conclusion of this lesson the trainee will be able to: 1. For~, p and 7 decays a) Write a typical equation for the production of each type
More informationRadiation and Radioactivity. PHYS 0219 Radiation and Radioactivity
Radiation and Radioactivity 1 Radiation and Radioactivity This experiment has four parts: 1. Counting Statistics 2. Gamma (g) Ray Absorption Half-length and shielding 3. 137 Ba Decay Half-life 4. Dosimetry
More informationQuestion. 1. Which natural source of background radiation do you consider as dominant?
Question 1. Which natural source of background radiation do you consider as dominant? 2. Is the radiation background constant or does it change with time and location? 3. What is the level of anthropogenic
More informationNuclear forces and Radioactivity. Two forces are at work inside the nucleus of an atom
Nuclear forces and Radioactivity Two forces are at work inside the nucleus of an atom Forces act in opposing directions Electrostatic repulsion: pushes protons apart Strong nuclear force: pulls protons
More informationPhysics 736. Experimental Methods in Nuclear-, Particle-, and Astrophysics. Lecture 3
Physics 736 Experimental Methods in Nuclear-, Particle-, and Astrophysics Lecture 3 Karsten Heeger heeger@wisc.edu Review of Last Lecture a colleague shows you this data... what type of reaction is this?
More informationBethe-Block. Stopping power of positive muons in copper vs βγ = p/mc. The slight dependence on M at highest energies through T max
Bethe-Block Stopping power of positive muons in copper vs βγ = p/mc. The slight dependence on M at highest energies through T max can be used for PID but typically de/dx depend only on β (given a particle
More informationDosimetry. Sanja Dolanski Babić May, 2018.
Dosimetry Sanja Dolanski Babić May, 2018. What s the difference between radiation and radioactivity? Radiation - the process of emitting energy as waves or particles, and the radiated energy Radioactivity
More informationThe next three lectures will address interactions of charged particles with matter. In today s lecture, we will talk about energy transfer through
The next three lectures will address interactions of charged particles with matter. In today s lecture, we will talk about energy transfer through the property known as stopping power. In the second lecture,
More informationRevision Guide for Chapter 18
Revision Guide for Chapter 18 Contents Student s Checklist Revision Notes Ionising radiation... 4 Biological effects of ionising radiation... 5 Risk... 5 Nucleus... 6 Nuclear stability... 6 Binding energy...
More informationAn Introduction to Diffraction and Scattering. School of Chemistry The University of Sydney
An Introduction to Diffraction and Scattering Brendan J. Kennedy School of Chemistry The University of Sydney 1) Strong forces 2) Weak forces Types of Forces 3) Electromagnetic forces 4) Gravity Types
More information11 Gamma Ray Energy and Absorption
11 Gamma Ray Energy and Absorption Before starting this laboratory, we must review the physiological effects and the proper use of the radioactive samples you will be using during the experiment. Physiological
More informationhν' Φ e - Gamma spectroscopy - Prelab questions 1. What characteristics distinguish x-rays from gamma rays? Is either more intrinsically dangerous?
Gamma spectroscopy - Prelab questions 1. What characteristics distinguish x-rays from gamma rays? Is either more intrinsically dangerous? 2. Briefly discuss dead time in a detector. What factors are important
More informationNeutrino detection. Kate Scholberg, Duke University International Neutrino Summer School Sao Paulo, Brazil, August 2015
Neutrino detection Kate Scholberg, Duke University International Neutrino Summer School Sao Paulo, Brazil, August 2015 Sources of wild neutrinos The Big Bang The Atmosphere (cosmic rays) Super novae AGN's,
More informationChapter 16 Basic Precautions
Chapter 16 Basic Precautions 16.1 Basic Principles of Radiation Protection The four basic methods used to control radiation exposure are time, distance, shielding, and contamination control. The first
More informationLecture Presentation. Chapter 21. Nuclear Chemistry. James F. Kirby Quinnipiac University Hamden, CT Pearson Education, Inc.
Lecture Presentation Chapter 21, Inc. James F. Kirby Quinnipiac University Hamden, CT Energy: Chemical vs. Chemical energy is associated with making and breaking chemical bonds. energy is enormous in comparison.
More informationDETECTORS. I. Charged Particle Detectors
DETECTORS I. Charged Particle Detectors A. Scintillators B. Gas Detectors 1. Ionization Chambers 2. Proportional Counters 3. Avalanche detectors 4. Geiger-Muller counters 5. Spark detectors C. Solid State
More informationU (superscript is mass number, subscript atomic number) - radionuclides nuclei that are radioactive - radioisotopes atoms containing radionuclides
Chapter : Nuclear Chemistry. Radioactivity nucleons neutron and proton all atoms of a given element have the same number of protons, atomic number isotopes atoms with the same atomic number but different
More informationAtoms, Radiation, and Radiation Protection
James E. Turner Atoms, Radiation, and Radiation Protection Third, Completely Revised and Enlarged Edition BICENTENNIAL J 0 1 8 0 Q 71 z m z CAVILEY 2007 1 ;Z z ü ; m r B10ENTENNIAL WILEY-VCH Verlag GmbH
More informationCHARGED PARTICLE IONIZATION AND RANGE
CHAGD PATICL IONIZATION AND ANG Unlike the neutral radiations (e.g., neutrons and gamma/x rays), the charged particles (e.g., electrons, protons and alphas) are subjected to the coulombic forces from electrons
More informationPage 1. ConcepTest Clicker Questions Chapter 32. Physics, 4 th Edition James S. Walker
ConcepTest Clicker Questions Chapter 32 Physics, 4 th Edition James S. Walker There are 82 protons in a lead nucleus. Why doesn t the lead nucleus burst apart? Question 32.1 The Nucleus a) Coulomb repulsive
More informationProperties of the nucleus. 8.2 Nuclear Physics. Isotopes. Stable Nuclei. Size of the nucleus. Size of the nucleus
Properties of the nucleus 8. Nuclear Physics Properties of nuclei Binding Energy Radioactive decay Natural radioactivity Consists of protons and neutrons Z = no. of protons (Atomic number) N = no. of neutrons
More information