title: Experimental HPGe coaxial detector response and efficiency compared to Monte Carlo simulations.
abstract: The peak efficiency for photons hitting the frontal surface of a medium volume n-type HPGe coaxial detector is mapped using acutely collimated beams of energies between 31 and 383 keV from a (133)Ba radioactive source. Simulated values obtained with the Monte Carlo radiation transport code penelope, using a model that respected actual detector dimensions and physical constants while varying dead-layer thicknesses, allowed us to fit the experimental results in the detector bulk but not near its rim. The spectra of a (137)Cs source were measured using the detector shielded from the natural background radiation, with and without a broad angle collimator. The corresponding simulated spectra, using the fitted dead-layer thicknesses, underestimate the continuum component of the spectra and overestimate the peak efficiency, by less than ten percent in the broad angle collimator arrangement. The simulated results are sensitive to the photon attenuation coefficients.
authors.affiliation: Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508:900 São Paulo, SP, Brazil.
authors.forename: Nora L
authors.initials: NL
authors.lastname: Maidana
authors.affiliation: Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508:900 São Paulo, SP, Brazil.
authors.forename: Vito R
authors.initials: VR
authors.lastname: Vanin
authors.affiliation: Instituto de Física, Universidade de São Paulo, Travessa R 187, Cidade Universitária, CEP:05508:900 São Paulo, SP, Brazil; Departamento de Física Nuclear, Instituto Superior de Tecnología y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana 10600, A.P. 6163, La Habana, Cuba.
authors.forename: Juan A
authors.initials: JA
authors.lastname: García-Alvarez
authors.affiliation: NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122 Essen, Germany; Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Pg. Vall d'Hebron 119-129, Barcelona 08035, Spain.
authors.forename: Marcelino
authors.initials: M
authors.lastname: Hermida-López
authors.affiliation: NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122 Essen, Germany. Electronic address: lorenzo.brualla@uni-due.de.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Brualla
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods; D015233:Models, Statistical; D009010:Monte Carlo Method; D017785:Photons; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012666:Semiconductors; D012680:Sensitivity and Specificity
keywords: Dead layer; Detector scan; HPGe detection efficiency; HPGe response function; Monte Carlo simulation