Topic 6 Nuclei and Particles Flashcards
In what two ways can mass be formed?
- Photons can collide to form a matter-antimatter pair.
- Matter-antimatter particles can form spontaneously from nothing using “burrowed” energy. They only exist briefly and then disappear as the energy needs to be repaid.
Relationship between energy and time equation
delta E x delta t ~ h / 4pi
where h is Planck’s constant, delta E is the precise specification of energy and delta t is the time interval.
How much energy is required to form a particle?
The specific energy of the mass of the particle and antiparticle would be required to create the particle pair.
If an electron had an energy mass of 510 keV, the photons that create the electron-positron pair would require a minimum energy of 1020 keV (1.02 MeV).
What are the 3 rules of conservation for nuclear processes?
- Electric charge is conserved: the net charge of the products of a nuclear process is the same as the net charge of the original nucleus or nuclei.
- Mass number is conserved: the total number of nucleons in the products is the same as that in the original nucleus or nuclei.
- Energy is conserved: as it is in all physical processes.
What is mass defect?
The mass of any needs is less than the total mass of the individual nerdcons of which it is composed. The difference is referred to as the mass defect of the nucleus, usually expressed in units of MeV/c^2.
What is binding energy?
The energy released when a nucleus is formed from its constituent nucleons.
What is binding energy per nucleon?
The binding energy of a nucleus divided by the number of nucleons of which it is composed. The nuclide with the largest binding energy per nucleon is iron-56 with a value of 8.8 MeV.
What is an alpha particle?
A helium 4 nucleus comprising of 2 protons and 2 neutrons.
What is alpha decay?
A nuclear decay process in which a nuclide emits an alpha particle. The binding energy of the products is more than that of the parent nuclide.
234U92 > 230TH90 + 4He2
What is beta minus decay?
A type of nuclear decay in which a neutron is converted into a proton with the emission of an electron (e-) and an electron antineutrino (νe with line over).
At a deeper level this may be understood as resulting from the conversion of a down quark to on up quark. All beta decays are examples of processes that depend on weak interactions.
This occurs in nuclei that have too many neutrons to be stable..
214Pb82 > 214Bi83 + e- + νe (line over top)
What is a beta-particle?
An election (or sometimes positron) produced in beta decay.
What is beta plus decay?
A type of nuclear decay where a proton is converted into a neutron with the emission of a position and an election neutrino.
At a deeper level it may be understood as resulting from an up quark converting into a down quark. All beta decay are examples of processes that depend on weak interactions.
Occurs in nuclei that have too few neutrons to stable.
14O8 > 14N7 + e+ + νe
What is electron capture?
A type of radioactive decay in which an atomic nucleus with too many protons captures an electron. The effect is for one proton to turn into a neutron with the emission of on electron neutrino. The effect on the nucleus is the same as beta plus decay.
It occurs in Medea that have too few neutrons to be stable.
26Al13 + e- > 26Mg12 + νe
What is gamma decay?
A type of nuclear decay in which a nuclide in an excited state emits a gamma ray photon and so makes a transition to a lower energy level.
What are gamma rays?
Electromagnetic radiation corresponding to the highest energy photons, or equivalentlythe shortest wavelength and highest frequency radiation.
What is a parent isotope?
A radioactive isotope that undergoes radioactive decay whose products are referred to as daughter isotopes.
What are daughter isotopes?
An isotope formed as a result of a radioactive decay from a parent isotope.
Calculating how many parent isotopes are left after n halflives?
P = (1/2)^n Po
Where P is the number of parent isotopes at any time, n is the number of half lives and Po is the initial number of parent isotopes.
Alternative forms:
P / Po = (1/2)^n
Po = 2^n P
Calculating the age of rock using daughter / parent ratios.
D = Po - p
D = 2^n P - P
D / P = 2^n - 1
Where D is the number of daughter isotopes present, P is the number of parent isotopes present, n is the number of half lives and Po is the initial number of parent isotopes.
What is nuclear fission?
A proceeds by where a relatively large nucleus splits apart into two less massive nuclei of roughly equal size.
This may occur spontaneously or induced by bombarding the nucleus with other particles.
What is a lepton?
A fundamental particle, the matter counterpart of an antilepton. There are six flavours of lepton: the electron (e-), muon (μ-), tauon (τ-), electron neutrino (νe), muon neutrino (νμ) and tauon neutrino (ντ).
What is a quark?
A fundamental particle of matter, the matter counterpart of an antiquark. There are 6 flavours of quark: up (u), down (d), charm (c), strange (s), top (t), and bottom (b).
Quarks are found in baryons and mesons but never in isolation.
What is a muon?
A negativity charged fundamental particle (lepton) similar to an electron but with a mass about 200 heavier. Its antiparticle is called on antimuon.
This particle is unstable and rapidly decays to an electron.
What is a tauon?
A negativity charged fundamental particle (lepton) similar to an electron but with a mass about 3500 heavier. Its antiparticle is called on antitauon.
This particle is unstable and rapidly decays to an electron.
