Virtual point detector: On the interpolation and extrapolation of scintillation detectors counting efficiencies

Validity of a virtual point detector model implying existence of a point where all interactions virtually occur was investigated for measuring the radioactivity of volume-ring sources. The dependency of the count rates on the distance between the virtual point detector and the detector surface for radioactive volume-ring sources with various radii was studied by MCNP4c simulations and the results were compared with the experimental data. Furthermore, the relationship between the virtual point detector and γ energy for the sources with various radii was investigated.

Section: Mathematical Methodologymentioning

confidence: 99%

“…The MCNP photon ring source was situated perpendicular to the detector x-axis so that its center was coincided on the detector axis. The full energy peak was recorded for various source detector distances (1,4,7,10,16,20, and 25 cm). The types of sources used in the γ rings as a multiple energy sources are presented in table 2.…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

HPGe virtual point detector for radioactive volume-ring sources

Nasrabadi

Kashi

2014

“…The VPD concept was also found to be applicable to point sources lying off the symmetry axis in non absorbing media [4] and expanded into the case with an absorbing medium between the source and the detector end-cap [5]. The VPD concept was confirmed for scintillation detectors [6]. The dependence of the VPD on the HPGe detector dimensions was determined [7].…”

Section: Introductionmentioning

confidence: 94%

Determination of the dependence of HPGe virtual point detector location on source dimensions in 60 keV–2 MeV range using Monte Carlo simulation

Çeli̇k

2012

The virtual point detector (VPD) concept for an HPGe detector with 55% relative efficiency was confirmed for bulky sources having different diameters and heights. After reproducing experimental data, Monte Carlo simulation was used to investigate the dependence of VPD location on photon energy for various source diameters and heights in the energy range from 60 keV to 2 MeV. The simulations were confirmed using a soil reference source prepared by International Atomic Energy Agency (IAEA). It was seen that increasing photon energy makes significant changes in VPD location up to 600 keV. It was observed that VPD locations increase with increasing source diameter and height. It was also seen that VPD locations were approximately linearly dependent on source diameters and heights. KEYWORDS: Models and simulations; Gamma detectors (scintillators, CZT, HPG, HgI etc); Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc)

“…It is noteworthy that virtual point detector is a mathematical concept and it is not surprising that in some cases such as planar thin detectors the virtual point detector is found to be outside the detector [3]. On the other hand, the same concept is applicable for other kinds of detectors such as NaI(Tl) [4]. Over past decades, a barrier in verification of virtual point detector concept has been inaccessibility to wide range of detectors with various sizes in the laboratory.…”

Section: Jinst 5 T05002mentioning

confidence: 99%

Dependence of the virtual point-detector location on HPGe detector dimensions and source energy in 80–1400 keV range

Taheri¹,

Sardari²

2010

Variations of VPD position inside HPGe detector as function of source photon energy and dimension of the detector is investigated. Monte Carlo code MCNP4C is employed to compute the detector efficiency for varying source-detector distance. The efficiency is measured in practice. The experimental results are obtained and compared with Monte Carlo output for energy range 80–1400 keV and source-detector distances 1–10 cm. it is shown that the depth of VPD increases with photon energy up to 600 keV and remains with little significant changes at higher energies. With increasing the detector radius the VPD is located deeper into the detector. The distance between VPD and entrance window is calculated to vary from 2 cm to 4 cm for detector radius between 2.5 cm to 4.7 cm.