Determination Of The Cr-39 Detection Efficiency For Infinite Film Geometry Source

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CR-39 is a polymer that registers the passage of energetic ions, which break chemical bonds from its molecular structure. Chemical etching of the damaged region produces channels, referred to as tracks, which can be visualized by optical microscopy. Surface track densities are related to the volumetric activity concentration of the source. Aiming at determining the efficiency factors relating these two quantities, U3O8 films, with thicknesses ranging from 4.1 to 20.7mg/cm2 were manufactured and coupled with CR-39 sheets for 10 minutes each. After etching, track densities were determined by counting under an optical microscope. By fitting these data with a geometrical model, it was possible to find values for parameters related to etching and counting efficiencies: θc=(77±3)°; η=0.71±0.05. A value of the 4.5 MeV alpha particle range was found: R=(8.7±1.3)mg/cm2. This estimated range is shorter than the one predicted by simulation with SRIM2008, indicating that tracks from alpha particles with energies below 0.7 MeV are not revealed or counted after etching. © 2011 American Institute of Physics.1351148151Brazilian Physical Society (SBF),Sao Paulo Research Foundation (FAPESP),Coordenacao Aperfeicoamento Pessoal Ensino Super. (CAPES),Rio de Janeiro Research Foundation (FAPERJ),National Research Council (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Paulo, S.R., (2005) Radiat. Meas., 39, pp. 657-660Iunes, P.J., (2004) J. Radioanal. Nucl. Chem., 262, pp. 461-468Mikado, S., (2009) Nucl. Instrum. Meth. A, 605, pp. 171-174Guedes, S., (2002) J. Radioanal. Nucl. Chem., 253, pp. 73-76Ziegler, J.F., (2008) SRIM - The Stopping and Range of Ions in MatterPratt, J.W., Edgenworth, F.Y., Fisher, R.A., (1976) The Annals of Statistics, 4, pp. 501-51