- The gamma ray hits a free electron and results in decrease energy of that photon.
- Is an interaction between a gamma ray and a free electron. After hitting the electron the gamma ray looses some of its energy.
When an element can gain or loose an electron. Ionization.
The nucleus contains protons and neutrons. Electrons orbitals K (can have up to 2 electrons), L (can have up to 8 electrons), and M (can have up to 8 electrons). Nuclear forces bind the nucleons in the nucleus. EM binds the electrons or orbitals to the nucleus.
Best method of protection:
- a) Time: more time away = less exposure
- b) Distance: More distance away = less exposure
- c) Shielding: apply shielding during injection
- B+ or B- less exposure by using plastics or tungsten
- x-ray and gamma less exposure by using lead
Nature of matter
Matter is made up of atoms consisting of neutrons, protons, and electrons.
- Any radiation as a stream of alpha particles or x-rays, that produce ionization as it passes through a medium.
- Process in which radiation carries enough energy to liberate electrons from atoms.
- Radiation is giving off during movement of electrons.
Describe the modes of decay
- 1)Alpha: nuclei having too many nucleons
- (neutrons &protons)
- 2)Beta:(Negatron decay)- Nuclei having more neutron than those needed
- for stability. Thus a neutron is converted into a proton.
- (Positron decay)- nuclei having fewer neutron than those needed
- for stability, excess protons
- 3)Gamma: high-energy, high-frequency EM
- radiations emitted by atomic nuclei following other modes of decay
- when the daughter nucleus still has some excitation energy available.
- Positron emitters are also considered gamma emitter because of the
- annihilation gamma rays produced upon decay.
4)Electron Capture (EC
):nucleus with a high number of protons absorbs an inner electron, there by changing a proton to a neutron
- 5)Isomeric Transition: Nucleus de-excites by emission of a delayed gamma ray, daughter is a nuclear isomer of parent **Same number of protons, same number of neutrons only the daughter has them
- arranged in more stable configuration
An attractive nuclear force existing between neutrons, between neutrons and protons, and between protons and protons. It is the "binding force" of the nucleus.
When a gamma ray is absorbed into the nucleus and the electron is ejected. This results in a shower of x-rays and or auger electrons.
What is radiation protection?
Protecting people in the environment from the harmful effects of ionizing radiation.
- 3 principles of ALARA are:
- a) time
- b) distance
- c) shielding
As Low as Reasonable Achievable
When an excited nucleus emission of de-excites by emisson of a delayed gamma ray.
A gamma ray interacts with a K electron. The gamma ray is absorbed and the electron is ejected. This results in a shower of x-rays.
an interaction between a gamma ray and the strong electrical field. The gamma ray is absorbed and results in a positron and negatron.
Is an interaction of a gamma ray with a tightly bound atomic electron, most likely a K-electron. The gamma ray is completely absorbed and the electron is ejected.
Is electromagnetic radiations. They have no mass and carry no electrical charge. Yet, they can cause ionization as they travel through matter.
a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously.
is a process that unstable atoms can use to become more stable. During electron capture, an electron in an atom's inner shell is drawn into the nucleus where it combines with a proton, forming a neutron and a neutrino. The neutrino is ejected from the atom's nucleus.
is a peak on a graph which plots the energy loss of ionizing radiation during its travel through matter. The peak occurs immediately before the particles come to rest.
"Braking Radiation", when a negatron passes near an atomic nucleus the attractive pull of the nucleus slows it down
- Any beta particles deflected by more than 90*. High z materials backscatter beta particles more than low Z materials. Backscatter can be a source of unexpected exposure.
- Some of the radiation after entering the tissue will scatter back toward the surface.
When a positron spends all its energy and comes to a stop, it attracts toward itself a free electron. In an instant both are converted into two photons 511 KeV each, traveling in opposite directions. Those are the photons detected in PET.
beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron and an antineutrino. The electron and antineutrino fly away from the nucleus, which now has one more proton than it started with. Since an atom gains a proton during beta-minus decay, it changes from one element to another. For example, after undergoing beta-minus decay, an atom of carbon(with 6 protons) becomes an atom of nitrogen (with 7 protons).
a proton in an atom's nucleus turns into a neutron, a positron and a neutrino. The positron and neutrino fly away from the nucleus, which now has one less proton than it started with. Since an atom loses a proton during beta-plus decay, it changes from one element to another. For example, after undergoing beta-plus decay, an atom of carbon (with 6 protons) becomes an atom of boron (with 5 protons).
Beta decay is one process that unstable atoms can use to become more stable. There are two types of beta decay, beta-minus and beta-plus.
An atom spits out 2 protons and 2 neutrons from it nucleus. Alpha decay is one process that unstable atoms can use to become more stable. Since an atom loses two protons during alpha decay, it changes from one element to another. For example, after undergoing alpha decay, an atom of uranium (with 92 protons) becomes an atom of thorium (with 90 protons).