Module 6 Part 2 Flashcards
What is a nucleon
A nucleon is a particle within the nucleus of an atom-a proton or neutron
What is nucleon number the same as
Atomic mass
What is the proton number the same as
Atomic number
What is the strong nuclear force and give some features of it
The force that keeps protons together
-it can only be experienced when the particles are very very close together and both positive
-transmitted by gluons which have very short half lives
-it is attractive between 1 and 3 fm and repulsive less than 0.75 fm
What is a fundamental particle + examples
A fundamental particle is a particle which cannot be broken down further.
Electrons
Positrons
Quarks (any)
What are the six types of quarks
Up, down, charm, strange, top, bottom
What are the 3 types of leptons
Electron, muon, tau (all have neutrino counterparts)
What are hadrons
Hadrons are any particle that is affected by the strong nuclear force
What are leptons
Leptons are any particle which are NOT affected by the strong nuclear force
What are the three fundamental particle families
Quarks, leptons and bosons
What are the two types of hadrons
Baryons and mesons
What is a baryon + example
A baryon is any particle made up of 3 quarks e.g. proton, neutron
What is a meson
A meson is any particle made up of a quark and an antiquark
What is the quark structure of a proton
up up down
What is the structure of a neutron
up down down
What happens when a particle and its antiparticle counterpart come into contact
They annihilate each other
What are the three types of radiation
Alpha, beta and gamma
What is alpha radiation and what are the features of it
Alpha radiation is a helium nucleus
Low penetrative power
High ionising power
Stopped by sheet of paper
What is beta radiation and what are the features of it
Beta radiation is a free electron
Medium penetrative power
Medium ionising power
Stopped by 1-10mm of aluminium
What is gamma radiation and what are the features of it
Gamma radiation is a high frequency EM wave
High penetrative
Low ionising power
Stopped by lead
What is transmutation
The process of an unstable isotope releasing energy and matter and often creating a new element
What is the names of the before and after isotopes in transmutation
Parent and daughter nuclei
What is a decay chain (decay series)
When a nucleus has to decay multiple times to become stable
What is activity and what is it measured in
Activity is the rate at which radioactive source emits radiation
Measured in becquerels
What are the two adjectives used to describe radiation
Spontaneous, random
What does spontaneous mean in relation to radioactivity
The decay of the nuclei is not affected by the presence of
other nuclei
external factors
What does random mean in relation to radioactivity
Each nucleus has an equal chance of decaying
cannot predict which one will decay next
What is half life
Half life is the time taken for half of the sample to decay
What is decay constant
The probability of decay per unit time for a nucleus of a specific material
What is radioactive dating and give an example
A method of dating a material by observing the number of radioisotopes in the sample with a known half life
For example carbon dating uses carbon 14 (half life of 5730 years) to date organic matter by observing how many carbon 14 isotopes are present and using this to calculate the age
What are three factors that can skew carbon dating data
Increased carbon due to global warming
Volcanic eruptions or natural disasters
Testing of nuclear bombs
What is binding energy
Binding energy is the energy required to separate nucleons from each other
What is mass defect and explain it
The mass defect is the difference in mass between a whole nucleus and its constituent nucleons
It is there due to energy being added to the system to overcome the binding energy and therefore adding mass due to the equation E=mc^2
What is the difference between nuclear fission and fusion
Fission=splitting of nucleus
Fusion=merging of nuclei
What is induced fission
When a nucleus becomes unstable upon having another particle absorbed into it
What is the name of a neutron slow enough to be absorbed by a nucleus
Thermal neutron
In a nuclear fission reactor, what are control rods, fuel rods and moderator used for
Control rods: absorbs excess neutrons so chain reaction does not get out of hand
Fuel rods: provides fissile material to begin reaction
Moderator: slows down output neutrons enough so that they can begin another reaction
What is an X-ray
An X-ray is a photon of electro magnetic radiation and it is of short wavelength and high energy
What is a non-invasive technique
A technique were the patient does not need to be harmed
What is the film on an X ray made of
Silver halide crystals
What is collimation and attenuation
Collimation=when spread out beams are all set parallel and in the same direction
Attenuation=when beams are partially absorbed meaning there intensity decreases
What are the four types of attenuation and there energy levels
Simple scatter-1-20 KeV
Photoelectric effect-30-100 KeV
Compton scattering-0.5-500 MeV
Pair production->1.02 MeV
Explain simple scatter attenuation
The x-ray strikes an electron and then is scattered away in a different direction
Explain photoelectric effect attenuation
An X-ray photon gives an electron enough energy to leave the atom and in a one-to-one interaction
Explain Compton scattering attenuation
The x-ray photon undergoes the photoelectric effect but still has residual energy which is spread out at a reduced frequency (simple scatter)
Explain pair production attenuation
When the photon has enough energy it converts into mass which is described by einstiens equation E=mc^2
however as charge must be conserved it created an electron positron pair
What are the three things the intensity after attenuation depend on
Energy of photons before-initial intensity
Thickness of substance permeated-in m
Type of substance-attenuation co efficient
What is the element used in gamma cameras and what is it decayed from
Technetium which is decayed from molybdenum
What is the compound of crystals that absorb energy from gamma rays and convert them into light
Sodium iodide
What are the three layers of the gamma camera and briefly explain
1-collimator-lead ‘straws’ only allow parallel beams to pass through
2-scintillator-sodium iodide crystals convert gamma photons to visible light photons by absorbing energy
3-receiving layer-a handful of receivers record the ratio of how much light they catch and then use this data to pinpoint the location of the source and then photomultiplier tubes convert this to an electrical signal
What does PET stand for
Positron emission tomography
Briefly explain how PET scanning works
A radioisotope tracer is injected into the patient which emits positrons
The positrons will inevitably encounter electrons after not very long
When they do they will annihilate and created a pair of photons
Depending on what the doctor is looking for they will insert different tracers which will be absorbed by different things more
What is ultrasound
Sound which has frequency over 20,000 Hz
What is the name of the crystals used in ultrasound transducers (piezoelectric)
Lead zirconate titanate (PZT)
What is the difference between ultrasound A scan and ultrasound B scan
Ultrasound A-in one dimension and used for things like the eye
Ultrasound B-in many dimensions built up using ultrasound A scans used for pregnancy screening etc.
What is a coupling medium
A substance (usually gel) which is the same density as what the ultrasound wave is entering to avoid interference at the boundary between the air and the object
What is acoustic impedance
The resistance of a material to the propagation of ultrasound waves
What is the equation for reflection co efficient
α=(Z₂-Z₁)^2/(Z₂+Z₁)^2
What is Doppler imaging
The imaging technique used for blood where the elongation or condensing of the wavelengths of the blood’s compressions indicates if the blood is moving towards or away from the observer
What is the Doppler imaging formula and state variables
Δf/f = 2Vcosθ/c
Where
f=original frequency
Δf=difference in original and received frequency
θ=angle between blood vessel and transducer
c=speed of ultrasound
v=speed of blood
What is the conditions needed for nuclear fusion
Very hot (high kinetic energy)
Very high pressure (increase chance of collisions)
