particles

Question 1

what is pair annihilation?

Answer 1

if a particle and its antiparticle collide they will annihilate each other and release two photons. Photons are released to conserve energy and momentum

Question 2

What is pair production?

Answer 2

an antiparticle and particle can be created by a photon, the photon must have energy greater than the rest mass of the combined particle and anti particle, the surplus will be used as kinetic energy.

Question 3

Leptons

Answer 3

Acted on by weak nuclear force, they are a fundamental particle and have a spin of +-1/2

Question 4

hadrons

Answer 4

baryons and mesons

Question 5

baryons

Answer 5

not fundamental, have a spin of +-1/2 or +-3/2 protons and neutrons> Proton is the only stable baryon

Question 6

mesons

Answer 6

they are not fundamental and are composed of quarks. they have very short life spans

Question 7

Quarks

Answer 7

up, down, strange, (anti)

Mesons are formed with a quark and anti quark.

Question 8

Strangeness

Answer 8

strange quark:
strangeness of -1.
anti strange quark has strangeness of 1.
all other quarks have strangeness 0.

Question 9

beta- decay

Answer 9

n–>p+e-+V(bar)e

udd–>uud+e-+V(bar)e

Question 10

beta+ decay

Answer 10

p–>n+e+ +Ve

uud–>udd+e+ +Ve

Question 11

Gravitation

Answer 11

force between masses
always attractive
range is infinite

Question 12

electromagnetic

Answer 12

between all charged bodies
can be attractive or repulsive
range is infinite

Question 13

weak nuclear force

Answer 13

acts on all particles
has a range of less than x10^-17m
responsible for beta decay
interactions involving change of quark type

Question 14

strong nuclear force

Answer 14

acts on hadrons and quarks
very short range(within nucleus)
holds the nucleus together
attractive at longer ranges, must overcome electrostatic repulsion between two protons
repulsive at short ranges to stop the nucleus collapsing

Question 15

interactions

Answer 15

electromagnetic-photon
weak-W+,W-,Z0 bosons
strong-gluon