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The spectra of monoenergetic alpha particles exhibit a well known asymmetric shape when measured with silicon detectors. The processes are described which determine the response of silicon detectors to alpha particles, particularly the energy dependence of the line shape. Particle implanted and passivated silicon (PIPS) detectors are assumed to have a thin dead layer at the front contact and an infinite sensitive volume. The incoming monoenergetic alpha particles lose energy in the dead layer where they develop a Gaussian energy distribution due to electronic energy-loss straggling. In the sensitive volume the alpha particles transfer most of their energy to electronic excitation and ionisation (E(s,e)) and the remaining fraction to the production of lattice vibrations and crystal damage. The statistical distribution of E(s,e) is calculated by a Monte Carlo simulation and shown to be asymmetric. The energy E(s,e) is subsequently used for the creation of electron-hole pairs. This model permits a quantitative calculation of the detector response function to alpha particles, and the result is in excellent agreement with measured spectra. On the basis of this model the energy dependence of the alpha particle line shape is also discussed.

Additional information

Authors: STEINBAUER E, Universität Linz, Institut für Experimentalphysik (AT);BAUER P, Universität Linz, Institut für Experimentalphysik (AT);BORTELS G, JRC Geel (BE);BIERSACK J P, Hahn-Meitner-Institut Berlin (DE);BURGER P, Canberra Semiconductor, Olen (BE);AHMAD I, Argonne National Laboratory, Illinois (US)
Bibliographic Reference: Paper presented: ICRM '93 Conference, Teddington (GB), June 7-11, 1993
Availability: Available from (1) as Paper EN 37480 ORA
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