1. Radiation Detection and Measurement, JU, 1st Semester, 2008-2009 (Saed Dababneh). 1 Radiation Sources Heavy nuclei are unstable against spontaneous emission of  particles. Barrier penetration. Higher energy ► easier penetration ► short half-life ► less practical. Lower energy ► less penetrability ► long half-life ► less activity. Most sources ► 4-6 MeV. Find the famous alpha sources and the corresponding energies and branching ratios. Most famous is 241 Am. Smoke detectors. Short range ► thin sources. Q-value. Recoil. Kinetic energy of  as a function of Q. Nuclear reactions as sources of  ’s. HW 8

2. Radiation Detection and Measurement, JU, 1st Semester, 2008-2009 (Saed Dababneh). 2 Radiation Sources HW 9 Different units used for sample (or target) thickness Charged particles. Gamma.

3. Radiation Detection and Measurement, JU, 1st Semester, 2008-2009 (Saed Dababneh). 3 Radiation Sources

4. Radiation Detection and Measurement, JU, 1st Semester, 2008-2009 (Saed Dababneh). 4 Radiation Sources Spontaneous fission. Transuranic isotopes (example 252 Cf). Also alpha emitters. Two fragments (and few neutrons) per fission. Fragments are positive ions (charge ~ Z). Usually thin coating on a flat backing. Only one fragment per fission escapes the sample. Strong energy loss. Heavy Light ? Induced Source of fragments and neutrons.

5. Radiation Detection and Measurement, JU, 1st Semester, 2008-2009 (Saed Dababneh). 5 Radiation Sources Many laboratory  sources are  sources. Need to be relatively thick source. Parent half-life and daughter energy! Catastrophic interaction. Energy and efficiency calibration. If for efficiency calibration, source needs to be thin, or correction factors. Small “width” compared to best detector resolution. Activity and effect on calibration. Annihilation TOI is better!