rad physics Flashcards
What part of the Atom is hardest to shield, why?
Neutrons - they have no charge
Rest mass of a neutron
939.6 MeV
Rest mass of a proton
939.6 MeV
Rest mass of an electron
0.511 MeV
Define AMU, and what is it normalized to?
Atomic Mass Unit, how atoms are weighed - normalized to C-12 (carbon-12)
Mass Number symbol and define
(A) - # protons + # neutrons
Atomic number symbol and define
(Z) - # protons
What is an Isotope
Same # Protons (Z)
ex. C-12 and C-14
What is an isotone
Same # Neutrons
ex. I-131 and Xe 132
What is an isobar
same Mass Number (A)
ex. N-14 and C-14
What is an isomer
same Z, A, and neutrons in a metastable state
Stability of atom with > 20 protons
atom must have 1.5 to 1, neutrons to protons
neutrons > protons
As Z number increases, binding energies ____?
Increase
Where do gamma rays originate from?
the nucleus
What do x-rays originate from?
Characteristic x-ray, and Bremsstrahlung x-ray
Describe Characteristic X-Ray
- orbital electron is ejected from atom
- An outer orbital e’ “falls down” to fill the vacancy
- E is radiated off in the form of electromagnetic radiation
- E of x-ray is the difference between corresponding energy levels (subtract e’ shells to determine E of x-ray)
Describe Bremsstrahlung X-Ray
- breaking radiation - can occur in any charged particle;
1. e’ is accelerated and deflected from passing by the nucleus;
2. e’ losses part of its E as electromagnetic radiation.
Does Bremsstrahlung Increase or Decrease with Z of target?
Increasees
Does Bremsstrahlung Increase or Decrease with e’ energy?
Increases
What kind of spectrum in bremsstrahlung x-ray?
continuous spectrum
Energy of scatted Neutron:
1/4 E of incoming neutron
Energy of Neutron at LINAC Door:
100-200 kev
On what side of the tx room door is borated poly for neutron shiedling?
LINAC side
