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· 108 m/sec speed of light m = 9.11 · 10-31 kg mass of electron 1 eV = 1,602-10-19 J 1 kev = 1,602-10-16 J 1. Relationship between X-ray frequency and wavelength: c = f1 here A is wavelength (m), ƒ is frequency (Hz), c is speed of light (m/sec). K - cathode A - anode electrons Х-гаys 2. Energy of X-rays photon: hc E = hfmax = Amin Amin is minimum wavelength of X-ray radiation (m), fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (J-sec), c 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: mv² eUa = 2 and then the kinetic energy of electron motion is transferred into energy of X-ray photons: ту? = hfmax 2 fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (J-sec) , c is speed of light propagation in vacuum (m/sec), e is charge of electron (C), m mass of electron (kg), Ua 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: 1.23 Amin(nm) = Ua(kV) Ua 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•³ •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, å is wavelength of X-ray radiation (m). 6. Mass attenuation coefficient (m²/kg): и = = ka3z3 Hm = 10-9 is coefficient of proportionality (W/V²A), p is density µ is linear attenuation coefficient, k of the material (kg/m³), Z is atomic number of the material, 2 is wavelength of X-ray radiation (m). 7. Attenuation of X-ray radiation intensity: 1 = I,e-ud here I, is the initial intensity of X-rays (W/m²); I is the intensity of X-rays after passing a material of thickness d (W/m²), d is thickness of the adsorbing layer (m), µ is linear attenuation coefficient (1/m). 8. Half value layer: In(2) 0,693 HVL = u is linear attenuation coefficient (1/m). 9. Determine the speed of the electrons incident on the anode surface of the X-ray tube if the minimum wavelength of the emitted X-ray radiation was 1 nm.