Radioactive Decay Flashcards
Alpha (α) particle
A particle emitted by the nucleus through α decay, containing 2 protons and 2 neutrons.
Identical to a helium nucleus.
Beta (β) particle:
A particle emitted by the nucleus through β decay, either negatively or positively charged.
β- particle: electron (“negatron”).
β+ particle: positron (antimatter, positively charged version of electron).
β- particle
electron (“negatron”)
Charge: 1.602 × 10^−19 coulombs.
β+ particle
A positron. (antimatter, positively charged version of electron)
Gamma (γ) ray
A photon emitted by the nucleus.
(different from an x-ray which is from an electron interaction (Bremsstrahlung) but may have the same energy range).
Internal conversion electron
Emitted when a nucleus transfers energy to an orbital electron instead of emitting a gamma ray
Characteristic X-ray
A photon emitted by an electron transitioning from one shell to another.
Other than the source of production, a 30-keV X-ray is identical to a 30-keV γ - ray.
(Compare with Auger electron)
Alpha (α) Decay
The nucleus is bloated, proton heavy and wants to lose weight!
Emission of alpha particles (2 neutrons and 2 protons)
Occurs in very heavy (Z > 52) nuclei.
Typical alpha energies range from 2 to 8 MeV.
Alpha particles are monoenergetic
Beta-Minus (β-) decay
The nucleus is proton-poor and wants more protons!
One of the neutrons is able to turn into a proton
Atomic number goes up by 1; mass stays the same.
electron and antineutrino is emitted.
Beta-Plus (β+) decay
The nucleus is proton-rich and wants more neutrons!
One of the protons turns into a neutron,
Atomic number goes down by 1; mass stays the same.
Positron (anti-electron) and a neutrino is emitted.
Electron Capture (EC)
The nucleus is proton-rich and wants more neutrons!
When nucleus is proton rich but does not have an excess of 1.02 MeV, the nucleus eats one of its electrons.
Electron combines with Proton to form a neutron. A Neutrino is emitted.
Remaining energy is emitted as a gamma ray or as internal conversion electrons
Characteristic X-rays due to filling of electron vacancy in inner shells.
Gamma Emission
The nucleus is excited and wants to settle down!
No change in atomic mass or atomic number.
Excess energy is released as a photon.
Internal Conversion
The nucleus is excited and it kicks out an electron!
The nucleus transfers internal energy to an inner shell electron which is freed.
Resulting vacancy is filled by higher electrons -> characteristic X-rays or Auger electrons.
Activity
Disintegration per second, Becquerel (Bq).
Exponential Decay
A = -λ · N
A(t) = A_0 · exp(-λ t)
