Radioactive Decays

So in week 7 we continue to increase of our scrutiny of the physical world by drawing our attention even deeper into the world of atom  by expanding our concerns with the nucleus itself. We have already seen last week how the orbital makeup of the electrons allow for chemistry to be possible by the give and take of electrons between elements.All that time we assumed a nucleus that was for the time being stable and being the sole reason the electrons did not fly off into space. Now we look inside the nucleus and find two main players in the neutron and the proton. The forces involved to keep the nucleus intact are immense as compared to the forces we have seen thus far. In fact the "strong force" which is yet another fundamental force of nature is the most formidable we have seen thus far and yet has a very short distance of action. THIS IS NOT the coulombic force the proton and electron share. This is the force between the neutron and the proton. A nucleus that is unstable will find the neutron decaying into a proton and several other elementary particles and energy or a proton transforming into a neutron with several other elementary particles and energy.  The three type of decay are alpha, where an atom emits a He nucleus of if you will, 2 protons and 2 neutrons. This results in a different element from what you started with. Example: U238 becomes Th234 + gamma radiation (energy greater than X -rays). Alpha radiation are usually only harmful if absorbed internally.  Next is Beta Decay. There are two types of this: Beta plus and Beta minus. Beta minus is more common and sees an electron, anti-neutrino resulting. Beta plus finds a positron (opposite sign of electron but same mass, if you will anti-matter), and neutrino.  Again a different element results because, the number of protons is altered but the atomic mass remains the same. This radiation is more penetrating to skin than alpha and exposure in larger amounts is a risk to all living things.Example of Beta Minus: 55Cs137 to 56Ba137 + electron + anti-neutrino. Example of Beta Plus: 11Na22 to 10Ne22 + positron + neutrino. Gamma radiation is not the result of changing elements. Rather it is created by the complete annihilation of anti-matter and matter. An electron and a positron for example. The number before in front is the atomic number of number of protons, the number after is the atomic mass which is the total mass of neutrons and protons combined. Gamma rays have tremendous energy and penetrating power. Disruption on a cellular as well as DNA level is apparent. (Are you out there Dr. Banner? aka The Hulk).  Alpha and Beta decay will exhibit predictive behavior not for individual atoms but for a larger masses. Here we will see in theory and in the lab how elements that decay can be determined how much and how long it takes. The use of such natural and human made elements in many fields is discussed in the text. Obviously the reality of nuclear physics is the Atomic Bomb and the Hydrogen Bomb. The tonnage of the A bomb is equivalent to 20,000 tons of TNT. The tonnage of the H bomb  has no limit but are said to have the equivalent of 50 million tons of TNT.  The A Bomb is fueled by nuclear fission or splitting of the atom. The H bomb is fueled by nuclear fusion which is fusing together nuclei of hydrogen. A more common use of fission and fusion is that of nuclear energy supplied by nuclear reactors which will be covered in week 8.

Physics in the Industrial Lab Part 4 - Radioactivity

Radioactivity is all around us. From natural radon emissions from the Earth and basement cinder blocks we test for an ventilate radon gas in our basements to hopefully not be exposed. In the lab we use several x ray producing equipment in SEM and TEM machines. While these machines are shielded, we still wear dosimeters that will record any radiation we might be exposed to. Many labs use radioactive isotopes in a controlled manner for a variety of test. CTL + Click on the link below to see more applications.  Crtl  + click to open in new tab window

  www.epa.gov/radiation/source-reduction-management/radionuclides.html

Radioactive Isotopes used in medicine

Besides being used in industry, radioisotopes are also used in medicine for diagnostics and treatment of disease and illness.

 CTRL + Click on the link 

www.world-nuclear.org/info/Non-Power-Nuclear-Applications/Radioisotopes/Radioisotopes-in-Medicine/