Radioactivity beta decay

Radioactive Decay

The behaviour projected by atomic nuclei as a result of nuclear instability is referred to as radioactivity. The atom’s nucleus starts to lose energy in the form of radiated radiation.

An experiment was used to confirm this phenomenon. Photographic plates were used to line a drawer. In the drawer was a little amount of Uranium compound wrapped in black paper. After a while, the plates were thoroughly scrutinised. They clearly demonstrated that they had been exposed to radiation. The term “radioactive decay” was used to describe this occurrence.

The presence of an unstable nucleus in the radioisotope of the element drains all of the energy. The atom particles are not bonded as a result of this. In order to stabilise themselves, the isotopes present are constantly decaying. This results in a large amount of energy being released in the form of radiation.

Types of Radioactive Decay

Alpha Decay, Beta Decay, and Gamma Decay are the three main types.

Alpha Decay or α-decay

The process by which a nucleus emits an alpha particle (helium nucleus) into a new atomic nucleus is known as alpha decay. The formula for alpha decay is as follows:

E=(mi–mf–mp)c2 

Here,

mi = initial mass of the nucleus

mf = mass of the nucleus after alpha particle emission

mp = mass of the emitted alpha particle

Example of Alpha Decay:

92238U90234Th+24He 

When 92238U undergoes alpha decay, it becomes 90234Th and24He  (containing two protons and two neutrons).

Beta Decay or β-decay

A beta particle (electron/positron) is emitted from an atomic nucleus during beta decay. The process of beta decay is as follows:

90234Th91234Pa+-10e 

Gamma Decay or γ-decay

The nucleus, like atoms, has different energy levels. When the nucleus’ high energy level transitions to a lower energy level, photons of MeV energy are emitted, earning the name gamma-ray.

Beta Decay Explanation

Beta decay is the transformation of a proton into a neutron or vice versa in radioactivity. This reaction takes place inside a radioactive sample’s nucleus. Both alpha and beta decay allow the nucleus to approach as close to the ideal proton or neutron as possible.

During this time, the nucleus emits a beta particle, which can be either a positron or an electron. What we must remember is that the positron is created in order to obey the charge conservation requirement. A proton can become a neutron or the other way around. Beta-decay is a weak interaction mechanism that occurs in the brain.

In a nutshell, beta decay is a feature of many naturally occurring elements and their isotopes that allows artificial isotopes of those elements to be created.

Beta Decay Procedure

The proton inside the nucleus decays into a neutron or vice versa in the process of Beta decay. The process of converting a neutron to a proton is known as (β-) decay, and the process of converting a proton to a neutron is known as (β+) decay. Due to a change in the nucleus, beta particles are emitted. And these particles are utilised to treat a variety of illnesses, including bone cancer and eye cancer. As tracers, beta particles are frequently used.

Beta Decay Types

The radioactivity beta decay is of two types: –

• Beta- Minus Decay (β-)

• A proton is converted in Beta Minus decay, resulting in an increase in the atomic number of the atom.
• To maintain charge conservation, the nucleus also produces an electron and an antineutrino during the process.
• The antineutrino is the antimatter counterpart of neutrinos. These are essentially massless neutral particles. Because the interactions of these particles with other matter are so faint, the earth as a whole is unaffected.

In beta-minus decay, the atomic configuration is:

ZAXZ+1AY+e–+ 

n=p+e–+ 

• Beta- Plus Decay (β+)

• The transition of a proton into a neutron in beta plus decay lowers the atomic number of the radioactive material. As a result, a proton is lost and a neutron is gained inside the nucleus.
• To maintain the law of conservation of charges, the beta decay process also produces a positron and a neutrino. Positron is a positive charge particle.
• Neutrinos behave similarly to antineutrinos in terms of behaviour.

The atomic configuration’s equation is:

ZAXZ-1AY+e++ 

p=n+e++ 

Beta Emission

The beta particles released by some radioactive nuclei are made up of high-energy, high-speed electrons, such as those found in potassium – 40. Although the penetration of beta particles is larger than that of alpha particles, the beta-gamma rays are still weak. Ionising radiation is emitted in the form of beta particles, which are also known as beta emission or beta rays.

Fermi’s Theory

The four fermions interact directly with one another at one vertex, according to Enrico Fermi’s suggested hypothesis. An electron is coupled with a neutron, a neutrino, and a proton in this type of interaction. Fermi first proposed this theory in 1933.

Radioactive Decay Law

When the number of radioactive nuclei decaying (α,β or γ decaying) per unit time is proportional to the total number of nuclei in the sample material, the radioactive decay law applies.

If N denotes the number of nuclei in a sample and ∆N denotes the number of radioactive decays per unit time ∆t, then

ΔN Δt∝ N

OR

ΔN Δt=λN

Here,

λ= proportionality constant or radioactive decay constant

ΔN= decrease in the total number of nuclei present in the sample

∂N/∂t=-λN………………………. Equation (1)

The above equation can also be written as:

∂N/N=-λ∂t………………. Equation (2)

Using the equations (1) and (2),

NoN∂N/N=-tot∂t

lnN-lnN0=-(t-t0)

Here,

N0= initial number of nuclei present in the sample at a time

When t0 is substituted for t=0 in the equation, the outcome is:

In(N/N0)=-λt

The final equation becomes:

N(t)=N0e–t0

Conclusion

Any of three radioactive disintegration processes in which some unstable atomic nuclei spontaneously waste surplus energy and suffer a one-unit positive charge change without changing their mass number. Electron emission, positron (positive electron) emission, and electron capture are the three processes. Ernest Rutherford termed beta decay in 1899 after noticing that radioactivity was not a simple occurrence. The fewer penetrating rays were dubbed alpha, while the more penetrating rays were dubbed beta. The majority of beta particles are released at near-light speeds.