Types of radioactive decay – Alpha Decay, Beta Decay – eSaral

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Hey, do you want to learn about the Types of Radioactive decay or Types of radioactive processes? If yes. Then you are at the right place.

Types of radioactive decay

(a) Alpha decay

$_{z} X^{A}$ (parent nucleus) $\longrightarrow_{Z-2} Y^{\mathrm{A}-4}$ (daughter nucleus)

$+{ }_{2} \mathrm{He}^{4}$ (alpha particle)

e. g. ${ }_{92} \mathrm{U}^{238} \longrightarrow{ }_{90} \mathrm{Th}^{234}+{ }_{2} \mathrm{He}^{4}$

  1. Alpha particle consists of 2 neutrons, 2 protons and carries a positive charge in magnitude 2 electrons. It is doubly ionized helium nuclei.

  2. $\alpha$ emission takes place when the size of the nucleus becomes too large. The decay reduces the size of the nucleus.

  3. $\alpha$ emission is explained on basis of the quantum mechanical tunnel effect.

  4. The energy released in $\alpha$ decay $\mathrm{Q}=\left(\mathrm{M}_{\mathrm{x}}-\mathrm{M}_{\mathrm{y}}-\mathrm{M}_{\alpha}\right) \mathrm{c}^{2}$

  5. The kinetic energy of $\alpha$ particle $\mathrm{E}_{\alpha}=\left(\frac{\mathrm{A}-4}{\mathrm{~A}}\right) \mathrm{Q}$ where A is mass number and Q is disintegration energy

(b) Beta decay

  • Electron emission

    $\left(\beta^{-}\right)$ ${ }_{z} X^{A} \longrightarrow_{z+1} Y^{A}$

    $+_{-1} \mathrm{e}^{0}\left(\beta^{-}\right.$ particle $)+\bar{v}$

    e.g. ${ }_{6} \mathrm{C}^{14} \longrightarrow{ }_{7} \mathrm{~N}^{14}$

    $+_{-1} \mathrm{e}^{0}+\bar{v}$ (antineutrino)

  1. $\beta^{-}$ Particles are fast-moving electrons carrying a negative charge

  2. $\beta^{-}$ Particles are emitted when the nucleus has too many neutrons relative to a number of protons i.e. N/Z ratio is larger than required.

  3. The emission of electrons takes place when a neutron is converted to a proton inside the nucleus. This helps in the correction of the N/Z ratio. ${ }_{0} \mathrm{n}^{1} \longrightarrow{ }_{1} \mathrm{p}^{1}+{ }_{-1} \mathrm{e}^{0}+\overline{\mathrm{v}}$

  4. The interaction responsible for $\beta$ decay is weak interaction.

 

  • Positron emission

    $\mathrm{z} \mathrm{X}^{\mathrm{A}} \longrightarrow \mathrm{z}_{-1} \mathrm{X}^{\mathrm{A}}$

    $+_{+1} e^{0}\left(\beta^{+}\right.$ particle $)+v$

    $\mathrm{eg} \cdot{ }_{29} \mathrm{Cu}^{64} \longrightarrow{ }_{28} \mathrm{Ni}^{64}$

    $+_{+1} \mathrm{e}^{0}+v$ (neutrino)

  1. $\beta^{+}$ Particles are positrons with a mass equal to an electron but carry a unit positive charge.

  2. $\beta^{+}$ Particles are emitted when the nucleus has too many protons relative to a number of neutrons i.e. N/Z ratio is smaller than required.

  3. The emission of positron takes place when a proton is converted to a neutron inside the nucleus. This increases the N/Z ratio.

    ${ }_{1} \mathrm{p}^{1}={ }_{0} \mathrm{n}^{1}+{ }_{+1} \mathrm{e}^{0}+\boldsymbol{v}$

 

(c) Gamma decay

${ }_{Z} \mathrm{X}^{\mathrm{A}^{*}} \longrightarrow{ }_{Z} \mathrm{X}^{\mathrm{A}}+\gamma$

e.g. $\quad{ }_{5} \mathrm{~B}^{12} \longrightarrow{ }_{6} \mathrm{C}^{12^{\star}}+{ }_{-1} \mathrm{e}^{0}+\overline{\mathrm{v}}$

${ }_{6} \mathrm{C}^{12^{*}} \longrightarrow{ }_{6} \mathrm{C}^{12}+\gamma$

  1. $\gamma$ rays are electromagnetic radiations that are chargeless and massless

  2. $\gamma$ rays are emitted when the nucleus has excess energy

  3. $\gamma$ rays are emitted when the nucleus jumps from the excited state to a lower level or ground state. This reduces the energy of the nucleus.

  4. $\gamma$ rays are electromagnetic radiations of short wavelength $\left(\sim 10^{-12} \mathrm{~m}\right)$ which travel with speed of light.

 

(d) Electron capture

${ }_{\mathrm{Z}} \mathrm{X}^{\mathrm{A}}+{ }_{+1} \mathrm{e}^{0} \longrightarrow+\underset{\mathrm{z}-1}{\mathrm{Y}}^{\mathrm{A}}+\mathrm{v}$

${ }_{4} \mathrm{Be}^{7}+{ }_{-1} \mathrm{e}^{0} \longrightarrow{ }_{3} \mathrm{Li}^{7}+\mathrm{v}$

  1. This process takes place when the nucleus has too many protons relative to a number of neutrons. i.e. N/Z ratio is larger than required.

  2. This process occurs when a parent nucleus captures one of its own orbital atomic electrons and emits a neutrino.

 

so, that’s all from this article. I hope you get the idea about the Types of Radioactive decay. If you found this article informative then please share it with your friends. If you have any confusion related to this topic then feel free to ask in the comments section down below.

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