Search results for "Gamma-ray Spectrometry"
showing 10 items of 17 documents
An experimental search for a correlation between outdoor 222Rn concentration and 210Pb activity in air particulate samples
2018
This work was aimed to search for a correlation between outdoor 222Rn air concentration and 210Pb activity in particulate samples collected on a filter. The existence of a correlation could support the hypothesis that both 222Rn and its long-lived product 210Pb are embedded into the same air masses and undergo the same air transport phenomena. Lead-210 activity was determined by means of gamma ray spectrometric measurement carried out a few days after the sampling whereas 222Rn concentration was measured through a commercial monitor. Experimental tests allowed to obtain a weak correlation between 222Rn and 210Pb air concentration as a preliminary result due to high uncertainties of outdoor …
Comparison of gamma-ray coincidence and low-background gamma-ray singles spectrometry
2011
Aerosol samples have been studied under different background conditions using gamma-ray coincidence and low-background gamma-ray singles spectrometric techniques with High-Purity Germanium detectors. Conventional low-background gamma-ray singles counting is a competitive technique when compared to the gamma-gamma coincidence approach in elevated background conditions. However, measurement of gamma-gamma coincidences can clearly make the identification of different nuclides more reliable and efficient than using singles spectrometry alone. The optimum solution would be a low-background counting station capable of both singles and gamma-gamma coincidence spectrometry.
Experiences of radioactivity measurement in various environmental samples
2013
An overview on our activity of environmental radioactivity measurement is reported. Radionuclide concentration have been evaluated in the particulate air, soils and rocks, drinking and surface water, wastewater, marine sediments and so on. Most of radionuclide concentration evaluation were performed using facilities of DEIM Department of Palermo University. In particular, particulate collection was performed by suction of atmospheric air through 45x45 Sofiltra-Poelman HYN-75 (Bleu type) cellulose filter paper using a high-volume air sampler located on the roof of our department building (20 m above ground-level), located within an undisturbed large park area in the city of Palermo (latitude…
Astronomical calibration of the Valanginian and the Hauterivian stages (lower cretaceous) : paleoclimatic and paleooceanographic implications
2013
Orbital floating time scales are proposed for the Valanginian Stage and part of the Hauterivian Stage (Early Cretaceous). These are based on the identification of the eccentricity cycles from spectral analyses performed on high-resolution climatic proxies measured on hemipelagic marl-limestone alternations. Five reference sections were analysed in the Vocontian Basin (SE France), spanning the entire Valanginian. A duration of 5,08 myr is proposed for the Valanginian Stage from the identification of the 405-kyr eccentricity cycle. The time frame proposed, combined with available radiometric ages, shows that the mid-Valanginian 13C positive excursion (namely the Weissert Event) occurs prior …
Equivalent detector models for the simulation of efficiency response of an HPGe detector with PENELOPE code
2019
Monte Carlo simulation of response of an HPGe detector is a widely used technique to evaluate counting efficiencies. It is particularly useful when calibration standards with the same shape and composition of the sample under examination are not available. The result of the simulation depends on the more or less detailed knowledge of the characteristics of the detector, able to define a "model" of the same detector. To highlight parts not well defined in the manufacturer's certification, a detector X-ray analysis is usually performed, except in cases when it is not possible to dismantle the shielding structure with the loss of previous calibration data. In this work, in absence of some data…
A radiometric and petrographic interpretation of discrepancies on uranium content in samples collected at Alte Madonie Mounts region (Sicily, Italy)
2013
Abstract The main goal of this work is to evaluate a correlation between anomalous Uranium (U) content and petrographic features of some soil and rock samples collected at Alte Madonie Mounts region (North-central Sicily, Italy). A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement to ensure that radioactive equilibrium between 226 Ra and 214 Bi was reached. Gamma-ray spectrometric analysis was used to quantify radioactivity concentrations. Mineralogical and chemical features of the samples were determined by X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Attenuated Total Reflection-Four…
A procedure to evaluate coincidence-summing correction values in gamma-ray spectrometry with HPGe detectors
2009
The spectrometric analysis of a gamma-emitter sample measured in "close geometry" can be affected by errors due to coincidence-summing effects that can occur when two or more coincident photons (real coincidences) within the resolution time of the spectrometric system are emitted. The probability that these effects occur depends primarily on the nuclide decay scheme, the sample-detector distance and detector intrinsic-efficiency whereas results independent from the sample nuclide activity. Coincidence-summing corrections of the photopeak areas are requested, in particular, when the gamma ray spectrometric analysis is aimed to efficiency or activity determination. In this work is reported a …
Coincidence-summing correction equations in gamma-ray spectrometry with p-type HPGe detectors
2011
Abstract Equations to compute γ−γ and γ−X K coincidence-summing corrections in gamma-ray spectrometry with p-type HPGe detectors are reported. For point sources only full-energy-peak and total efficiencies are needed.
MCNP5 modelling of HPGe detectors for efficiency evaluation in gamma-ray spectrometry
2009
A modelling of HPGe detectors was performed through simulation with the MCNP5 Monte Carlo code. The simulation results concerning the values of the main physical parameters of the detector are in most cases different from those provided by the manufacturer. The use of “single-line” sources allows us to suitably modify the parameter values used in the detector model. For a detector model, the simulation assesses the distribution of photopeak and total efficiency for point sources, whereas for extended sources a control volume approach allows us to determine elementary efficiency behaviours. An integration of elementary efficiencies over the entire sample volume allows us to evaluate global e…
Virtual point detector: Application to coincidence-summing correction in gamma-ray spectrometry
2009
The use of an efficiency transfer method based on the virtual point detector approximation to evaluate coincidence-summing correction values for point and volume sources was examined. The method was validated by means of a comparison with experimental efficiency determinations.