Experiments with radioactive elements
complex composition of radiation was detected by a simple experiment.Sample uranium placed in a lead box with a small opening.Opposite the hole put a magnet.It has been recorded that the radiation "split" into 2 parts.One of them is deviated towards the north pole, and the other - in the southern side.The first named alpha-rays, and the second - beta radiation.At the time, I did not know that there is a third type of gamma rays.They do not respond to the magnetic field.
Alpha decay - this is the core of the emission of a certain chemical element positively charged helium nuclei.This works displacement law, and he turns into a different element with another charge and mass number.Charge number decreases by 2 and the mass - in the nucle
i of helium 4, emitted from the nucleus in the decay process called alpha particles.They were first discovered by Ernest Rutherford in his experiments.He also opened the possibility of the transformation of one element into another.This discovery marked a turning point in the whole of nuclear physics.
Alpha decay characteristic of the chemical elements, in which there are at least 60 protons.In this case, the conversion of radioactive nuclei is energetically favorable.The average energy released by alpha decay, in the range of 2 to 9 MeV.Almost 98% of this energy carries with it a helium nucleus and the rest to return in the decay of the parent nucleus.
half-life of alpha emitters takes different values from 0.00000005 seconds to 8 billion years.Such a large spread is due to a potential barrier that exists inside the nucleus.It does not allow the particles to fly out of it, even if it is energetically favorable.According to the concepts of classical physics, the alpha particle in general can not overcome the potential barrier, as its kinetic energy is very small.Quantum mechanics has introduced its own corrections to the theory of alpha decay.With some probability the particle can still penetrate through the barrier, despite the lack of energy.This effect is called tunneling.Was introduced transmittance, determines the probability of a particle passing through the barrier.
large spread half-lives of alpha-emitting nucleus is due to the different height of the potential barrier (ie the energy to overcome it).The higher the barrier the larger the half-life.
- Alpha decay