X-RAY RADIATION Constants Units of Energy h = 6.626 · 10-34 J.sec Planck constant e = 1.6· 10-19 C charge of electron c = 3. 10 m/sec speed of light m = 9.11· 10-31 kg mass of electron 1 eV = 1,602-10- J 1 kev = 1,602-10- J 1. Relationship between X-ray frequency and wavelength: c = fA here A is wavelength (m), f is frequency (Hz), c is speed of light (m/sec). K- cathode A - anode Х-гауs electrons 2. Energy of X-rays photon: E = hfmax = Атin Amin is minimum wavelength of X-ray radiation (m), fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (J-sec), is speed of light propagation in vacuum (m/sec). 3. In the X-ray tube, firstly, the energy of electric field is transformed into the kinetic energy of electron motion: ту? eU, = and then the kinetic energy of electron motion is transferred into energy of X-ray photons: ту? 7 = h fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (J-sec), c is speed of fmax light propagation in vacuum (m/sec), e is charge of electron (C), m mass of electron (kg), Ug is potential difference or voltage between cathode and anode (V), v is speed of electrons motion (m/sec). 4. Relationship between wavelenth of X-ray radiation and Voltage on the tube: Amin(nm) = v.(kV) 1.23 U, is potential difference or voltage between cathode and anode (V), Amin is minimum wavelength of X-ray radiation (m). 5. Linear attenuation coefficient (1/m): µ = k•p•i² •Z³, k = 10-9 is coefficient of proportionality (W/V²A), p is density of the material (kg/m³), Z is atomic number of the material, i is wavelength of X-ray radiation (m). 6. Mass attenuation coefficient (m/kg): Hm = = ka³23 µ is linear attenuation coefficient, k = 10-9 is coefficient of proportionality (W/VA), p is density of the material (kg/m'), Z is atomic number of the material, i is wavelength of X-ray radiation (m). 7. Attenuation of X-ray radiation intensity: | = Le-ud here I, is the initial intensity of X-rays (W/m?); / is the intensity of X-rays after passing a material of thickness d (W/m?), d is thickness of the adsorbing layer (m), u is linear attenuation coefficient (1/m). 8. Half value layer: In(2) 0,693 HVL = u is linear attenuation coefficient (1/m). 7. (a) What is the energy of an X-ray photons, if it corresponds to a wavelength of 0.005 nm? (b) Find corresponding frequency of X-ray radiation.