Particles definitions

Question 1

alpha radiation

Answer 1

particles that each consist of two protons and two neutrons

Question 2

annihilation

Answer 2

When a particle and its antiparticle meet, they destroy each other and become radiation.

Question 3

antibaryon

Answer 3

A hadron consisting of three antiquarks.

Question 4

antiparticle

Answer 4

There is an antiparticle for every type of particle. A particle and its corresponding antiparticle have equal rest mass and, if charged, equal and opposite charge.

Question 5

atomic number Z

Answer 5

The number of protons in the nucleus of an atom.

Question 6

baryon

Answer 6

A hadron consisting of three quarks.

Question 7

beta radiation

Answer 7

Fast moving electrons emitted by unstable neutron-rich nuclei fast moving positrons emitted by unstable proton-rich nuclei.

Question 8

electromagnetic interaction (or force)

Answer 8

interaction (or force) between two charged objects

Question 9

electron capture

Answer 9

Process in which an inner-shell electron of an atom is captured by the nucleus.

Question 10

gamma radiation

Answer 10

High-energy photons emitted by unstable nuclei or produced in particle annihilations.

Question 11

hadron

Answer 11

particles and antiparticles that can interact through the strong interaction and are made up of quarks

Question 12

isotopes

Answer 12

atoms of the same element with different numbers of neutrons and the same number of protons

Question 13

kaon (or K meson)

Answer 13

a meson that consists of a strange quark or antiquark and another quark or antiquark

Question 14

lepton

Answer 14

Particles that cannot interact via the strong interaction e.g. electrons, muons, neutrinos.

Question 15

lepton number

Answer 15

A lepton number is assigned to every lepton (+1) and antilepton (-1), on the basis that the total lepton number for each branch of the lepton family is always conserved.

Question 16

meson

Answer 16

A hadron consisting of a quark and an antiquark.

Question 17

nucleon

Answer 17

A neutron or proton in the nucleus.

Question 18

nucleon number

Answer 18

A the number of neutrons and protons in a nucleus; also referred to as mass number.

Question 19

nuclide

Answer 19

A type of nucleus with a particular number of protons and neutrons.

Question 20

pair production

Answer 20

When a gamma photon changes into a particle and an antiparticle.

Question 21

pion (or π meson)

Answer 21

A meson that consists of an up or down quark and an up or down antiquark.

Question 22

positron

Answer 22

antiparticle of the electron

Question 23

rest energy

Answer 23

Energy due to rest mass. E = mc^2, where c is the speed of light in free space.

Question 24

specific charge

Answer 24

charge to mass ratio

Question 25

strangeness number

Answer 25

Strangeness of a strange quark = -1, strangeness of an anti-strange quark = +1. Strangeness is always conserved in the strong interaction, but not in a weak interaction or a weak decay involving a strange quark or antiquark.

Question 26

strong interaction

Answer 26

Interactions that only hadrons can undergo.

Question 27

strong nuclear force

Answer 27

Attractive force between nucleons that holds the nucleons in the nucleus.

Question 28

virtual photon

Answer 28

Exchange particle of the electromagnetic force; a photon exchanged between two charged particles when they interact.

Question 29

W boson

Answer 29

Exchange particle of the weak nuclear force; W bosons have non-zero rest mass and may be positive or negative.

Question 30

weak nuclear force

Answer 30

Force responsible for beta decay.