Particle Physics

Particle and radiation revision

What particles make up and Atom?

Electrons, neutrons, Protons

How do you calculate specific charge?

$$\frac{charge}{mass}$$

units Ckg^-1

what is the mass of a proton?

1.67×10^-27 kg

what is the mass of a neutron?

1.67×10^-27 kg

what is the mass of an electron?

9.11×10^-31 kg

what is the charge of a proton?

1.6×10^-19 C

what is the charge of a neutron?

0 C

what is the charge of an electron?

-1.6×10^-19 C

what is are isotopes?

Atoms of the same element (same number of protons), but they have different number of neutrons

how do you write isotopes

$${}_{Z}^{A}\text{X}$$

X - symbol, A - nucleon number, Z - proton number

how is EM radiation emitted?

an electron moving down a level, a particle rapidly losing its kinetic energy, oscillations of electrons in a wire

EM radiation are propagations of what two feilds

electric and magnetic fields which meet at right angles

what are the parts of EM spectrum

radio waves, micro waves, infrared radiation, visible light, ultraviolet, x-rays, gamma-rays

what is the wave equation?

$$c=f\lambda$$

what is the equation for wave energy?

$$E=hf$$

what is h in the wave energy equation?

h is Planck’s constant

how many joules is 1eV?

1.6×10^-19 J

what is the particle of light called?

a Photon

what is the equation for α decay?

$$^{A}_{Z}X \rightarrow ^{A-4}_{Z-2}Y + ^{4}_{2}\text{He}$$

how far does α travel in air, and what is it stopped by?

a few mm, stopped by paper or skin

what is equation for β decay?

$$^{A}_{Z}X \rightarrow ^{A}_{Z+1}Y + e^{-} + \bar{\nu}_{e}$$

how far does β^- travel in air, and what stops it?

a few cm, stopped by a sheet of aluminium

what is equation for γ decay?

$$^{A}_{Z}\text{X}^{*} \rightarrow ^{A}_{Z}\text{X} + \gamma$$

how far does γ travel, and what stops it?

infinite range, stopped by lead

what is an α particle?

a He nucleus, 2 protons 2 neutrons

what is a β^- particle?

an electron

what is γ radiation?

a high energy γ-ray

what proves the existence of gamma radiation?

β^- decay released a spectrum of energy, thus didn’t follow the conservation of energy, so there must be the neutrino

why must there be the strong nuclear force in a nucleus?

the electrostatic force of repulsion is much stronger than the force of gravity in the nucleus, so there must be another strong force holding the nucleus together, the strong nuclear force

how does the strong nuclear force vary with distance?

up to 0.5fm it is very repulsive, then up to 3 fm it is attractive.

why are large nuclei unstable, and α emitters?

they nucleus is too big, due to the strong force being limited to 3fm and is unable to reach all nucleons, whist the electrostatic force has an unlimited range

what is the fundamental strong force, and what is its gauge boson?

the force that hold quarks together, mediated by the gluon

what is the residual strong force, and what is its gauge boson?

the force that holds nucleons together, mediated by the virtual π meson (pion)

what is the mass of an antimatter particle compared to its normal counterpart?

its the same

what is the charge of an antimatter particle compared to its normal counterpart?

Its the opposite

what is the half life of an unstable antimatter particle compared to its normal unstable counterpart part?

its the same

what happens when an antimatter particle meets its normal counterpart part?

they annihilate each other, converting both of their masses to energy in γ rays

what equation links mass to energy

$$E=mc^2$$

what happens when there is a γ ray with more energy than the rest energy of a matter antimatter particle pair?

pair production, the γ ray converts its energy to an antimatter particle and normal matter particle, any extra energy is converted to kinetic energy of the particles.