Ionizing Radiation Prelude What’s the relevance of this class? Radiation: A History of Modern Physics 1895: Wilhelm Conrad Roentgen: x-rays (1901: first Nobel Price, Physics) 1896: Henri Becquerel: Uranium salt radioactive (NP 03) 1897: Joseph John Thomson: Cathode rays are particles, nature independent of materials! (NP 06) 1898: Marie+Pierre Curie: Radium and Polonium radioactive (NP 03, NC11), 1/2 Ernest Rutherford: α,β rays (NC 08) 1912: Victor Hess: Cosmic Radiation (NP 36) J.J. Thomson: Neon 20/22 Dec. 22, 1895 Radiation: A History of Modern Physics (cont.) Cloud Chamber 1932: James Chadwick: neutrons (NP 35) Aug. 2, 1932 Harold Urey: deuteron (NC 34) Carl D. Anderson: positron (NP 36) John D. Cockcroft, Ernest T.S. Sinton: Accelerator induced fission (NP 51) Ernest O. Lawrence: Cyclotron(NP 39) 1933: Enrico Fermi: β decay (NP 38) 1934: Irene Curie+Frederic Joliot: induced radioactivity (NC 35) Lead plate 1937: J. C. Street+M. L. Stevenson:2 µ 1938: Otto Hahn+Fritz Strassmann: Why is the trajectory bent? fission (NC 44) Which way did the particle go? (And how do you know?) The Nuclear Age A 1946 test of an atomic bomb in the lagoon at Bikini atoll. The Nuclear Age (cont.) Found on http://www.aip.org/history/einstein/index.html "Because of the danger that Hitler might be the first to have the bomb, I signed a letter to the President which had been drafted by Szilard. Had I known that the fear was not justified, I would not have participated in opening this Pandora's box, nor would Szilard. For my distrust of governments was not limited to Germany." The photograph shows a postwar reconstruction of the signing. Discovery of Radiation led to useful application in other fields Example: Elementary particle physics Discovery of Radiation led to useful application in other fields (cont.) Example: Astrophysics Photomultiplier Whipple/VERITAS: Detection of gamma rays HiRes: Detection of Cosmic rays Discovery of Radiation led to useful application in other fields (cont.) Example: Medical Physics -> MeV electrons or gamma rays are used to destroy tumors planned carbon ion and early cancer treatment proton therapy unit, siemens with radium Discovery of Radiation led to useful application in other fields (cont.) Example: Biology Carry out research in molecular structural biology by using the special properties of the synchrotron radiation Study of proteins (crystal structure of cellulosomal endoglucanase CelA in complex with substrate at 0.94 Å resolution (Guerin et al, 2002)) Material to be covered, outline • Basics on nuclear processes, radiation, units, biological effects etc. • Interaction of radiation with matter • various radiation detector concepts (PMTs, gaseous detectors, scintillators …) • Applications in various fields (see before).