TY - JOUR
T1 - Detector resolution in positron annihilation Doppler broadening experiments
AU - Heikinheimo, J.
AU - Ala-Heikkilä, J.
AU - Tuomisto, F.
PY - 2017/9/21
Y1 - 2017/9/21
N2 - Positron annihilation Doppler broadening spectroscopy characterizes lattice point defects and is sensitive to very small vacancy densities. High-purity germanium detectors are generally used for recording the Doppler broadening spectrum because they provide good energy resolution and stability. However, the energy resolution of a germanium detector is somewhat dependent on the photon absorption geometry in the detector crystal. This change in the energy resolution changes also the Doppler broadening parameters. To observe the dependency of the resolution function and the Doppler broadening parameters, we performed experiments on Si samples in standard sandwich configuration with a Na-22 source. We changed the radiation geometry of the incident gamma photons via altering the distance of the sample-source package from the detector and by adding steel between the source and the detector. We observed the change of the absorption geometry in the germanium detector crystal by doing Monte Carlo simulations. The aim of this study is to help understand and decide what is the best way to compare the Doppler broadening parameters obtained with different measurement setups and even with the same setup when the geometry in the measurements has changed.
AB - Positron annihilation Doppler broadening spectroscopy characterizes lattice point defects and is sensitive to very small vacancy densities. High-purity germanium detectors are generally used for recording the Doppler broadening spectrum because they provide good energy resolution and stability. However, the energy resolution of a germanium detector is somewhat dependent on the photon absorption geometry in the detector crystal. This change in the energy resolution changes also the Doppler broadening parameters. To observe the dependency of the resolution function and the Doppler broadening parameters, we performed experiments on Si samples in standard sandwich configuration with a Na-22 source. We changed the radiation geometry of the incident gamma photons via altering the distance of the sample-source package from the detector and by adding steel between the source and the detector. We observed the change of the absorption geometry in the germanium detector crystal by doing Monte Carlo simulations. The aim of this study is to help understand and decide what is the best way to compare the Doppler broadening parameters obtained with different measurement setups and even with the same setup when the geometry in the measurements has changed.
KW - Doppler broadening spectroscopy
KW - Energy resolution
KW - High-purity germanium detector
KW - Positron annihilation spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85021734010&partnerID=8YFLogxK
U2 - 10.1016/j.nima.2017.06.018
DO - 10.1016/j.nima.2017.06.018
M3 - Article
AN - SCOPUS:85021734010
SN - 0168-9002
VL - 867
SP - 215
EP - 221
JO - NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH SECTION A: ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
JF - NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH SECTION A: ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
ER -