Activity

Radioactive Activity.

Radioactive materials goes through exponential decay, and it is described as half life. Half life for a radioisotope is the time it takes for half of the radioactive nuclei to undergo radioactive decay. There are three main types of radioactive decay alpha, beta and gamma. (Alpha decay happens when a nucleus sheds an alpha particle which consist of two protons and two neutrons. Beta decay happens when a nucleus  sheds  an electron and gamma happens when a nucleus sheds an alpha or beta particle). Exponential decay can also occur in biological system and it is described as effective half life.

The radioactive physical half life for a given radioisotope is a measure of the tendency for a nucleus to decay or disintegrate and it is based purely on probability. Physical half life is constant over the lifetime of a radioisotope and it is independent from any outside influences like: temperature, pressure or its physical state. The only thing that can create a change in half life is an other radioactive material. One of the simple ways to calculate the exponential decay/ half life of a radioactive material is by multiplying the elapsed time with Log 2 then, divide it by the logarithm of mass in the beginning divided by mass at the end of elapsed time.

Effective half life is used in medicine and its used to determine what is going to happen to the radioactive isotope in a given amount of time when introduced externally to a body. Two main examples would be radiation therapy for cancer, (which is eliminated due to decay) and   radiocontrast iodine which  is used in the body to view blood vessels and changes in tissues. Effective half life is often approximated because it is difficult to precisely calculate it unlike physical half life.

In Conclusion, physical and effective Half-life is used to describe a quantity undergoing exponential decay and each radioactive nucleus has a certain probability of decaying, but whether it actually does is determined randomly.

References: "Effective Half-life." Wikipedia. Wikimedia Foundation, 23 Nov. 2013. Web. 06 Dec. 2013. "Half-life, Effective." Half-life, Effective. N.p., n.d. Web. 06 Dec. 2013. "Radioactive Half-Life." Radioactive Half-Life. N.p., n.d. Web. 05 Dec. 2013.