Duduli

Geiger & nuttal measured the range of alpha particles emitted by several radioactive elements & found that there exists a regular relationship between the ranges & the half lives of the elements. The relationship is expressed as      log10(λ)=A+Blog10(R) Where, R=Range of alpha particles             λ=disintegration constant       A & B = constant ★ Geiger nuttal law in terms of energy     log10(λ)=K+Clog10(E) Where,E=energy of alpha particles          K & C = constant ★ shorter half lives alpha particles have greater kinetic energy.while longer half lives alpha particles have lower kinetic energy.

According to tunnel effect, if a particle is impinging (means strike) on a barrier, with energy less than the height of the potential barrier, it will not necessarily be reflected by the barrier but there is always a probability to cross the barrier and continue its forward motion.

The range of α-particles is customarily defined as the distance which these particles travel through air at 76cm of mercury pressure and 15°C temperature before they lose their energy to the extent that they no longer ionise the gas particles. ★The range of α-particles depends upon the following factors (i) Initial velocity of α-particle (ii) Nature of emitting radioactive element (iii) Nature & pressure of the gas or nature of absorber.