Browsing by Author "Gundogdu O."

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A practical method for in-situ thickness determination using energy distribution of beta particles
(2012-01-01) Yalcin S.; Gurler O.; Gundogdu O.; Bradley D.
This paper discusses a method to determine the thickness of an absorber using the energy distribution of beta particles. An empirical relationship was obtained between the absorber thickness and the energy distribution of beta particles transmitted through. The thickness of a polyethylene radioactive source cover was determined by exploiting this relationship, which has largely been left unexploited allowing us to determine the in-situ cover thickness of beta sources in a fast, cheap and non-destructive way. © 2011 Elsevier Ltd.
An analytical expression for electron elastic scattering cross section from atoms and molecules in 1.0 keV to 1.0 MeV energy range
(2006-07-31) Yalcin S.; Gurler O.; Gultekin A.; Gundogdu O.
In this Letter, an expression is presented to calculate elastic scattering cross sections for incident electrons as a function of both energy and atomic number in the energy range between 1 keV and 1 MeV for materials with effective atomic number between 3 and 18. The expression we present has a rather simple analytical form which gives accurate results that are in very good agreement with the results calculated by a relativistic partial-wave expansion method. Hence, this equation can be employed accurately and efficiently in a continuous manner, without the need to go through rather large look-up tables, thus making the whole process quick, efficient and removing possible computational errors that may arise from the efforts of interpolation. © 2006 Elsevier B.V. All rights reserved.
Analytical investigation of energy spectrums of beta rays emitted from ⁹⁰Sr and ²⁰⁴Tl radioisotopes
(2011-01-01) Yalcin S.; Gurler O.; Gundogdu O.; Akar U.
The energy spectra of beta rays emitted from 90Sr and 204Tl radioisotopes were obtained by using a silicon surface barrier detector with a 1000 μm depleted layer and 50 mm2 effective area. The detector response function is interpreted by making use of range distributions of mono-energetic electrons in matter and by assuming a linear energy loss along the range in the depleted layer of the detector. An analytical expression is given for pulse height distribution obtained in the surface barrier detector. A good agreement is observed between the experimental results and theoretical interpretation. © 2011 Akadémiai Kiadó, Budapest, Hungary.
Calculation of angular distribution of 662 keV gamma rays by Monte Carlo method in copper medium
(2009-12-01) Kahraman A.; Ozmutlu E.; Gurler O.; Yalcin S.; Kaynak G.; Gundogdu O.
This paper presents results on the angular distribution of Compton scattering of 662 keV gamma photons in both forward and backward hemispheres in copper medium. The number of scattered events graph has been determined for scattered gamma photons in both the forward and backward hemispheres and theoretical saturation thicknesses have been obtained using these results. Furthermore, response function of a 51×51 mm NaI(Tl) detector at 60° angle with incoming photons scattered from a 10 mm thick copper layer has been determined using Monte Carlo method. © 2009 Elsevier Ltd. All rights reserved.
Calculation of total counting efficiency of a NaI(Tl) detector by hybrid Monte-Carlo method for point and disk sources
(2007-10-01) Yalcin S.; Gurler O.; Kaynak G.; Gundogdu O.
This paper presents results on the total gamma counting efficiency of a NaI(Tl) detector from point and disk sources. The directions of photons emitted from the source were determined by Monte-Carlo techniques and the photon path lengths in the detector were determined by analytic equations depending on photon directions. This is called the hybrid Monte-Carlo method where analytical expressions are incorporated into the Monte-Carlo simulations. A major advantage of this technique is the short computation time compared to other techniques on similar computational platforms. Another advantage is the flexibility for inputting detector-related parameters (such as source-detector distance, detector radius, source radius, detector linear attenuation coefficient) into the algorithm developed, thus making it an easy and flexible method to apply to other detector systems and configurations. The results of the total counting efficiency model put forward for point and disc sources were compared with the previous work reported in the literature. © 2007 Elsevier Ltd. All rights reserved.
Erratum: Analytical investigation of energy spectrums of beta rays emitted from ⁹⁰Sr and ²⁰⁴Tl radioisotopes (Journal of Radioanalytical and Nuclear Chemistry (2011) DOI: 10.1007/s10967-011-1198-4)
(2011-09-01) Yalcin S.; Gurler O.; Gundogdu O.; Akar U.
Evaluation of radon concentration in well and tap waters in Bursa, Turkey
(2012-06-01) Akar Tarim U.; Gurler O.; Akkaya G.; Kilic N.; Yalcin S.; Kaynak G.; Gundogdu O.
222Rn measurements in water samples collected from 27 wells and 19 taps that were supplied from the investigated wells were conducted using the AlphaGUARD PQ 2000PRO radon gas analyser at sites across several geologic formations within the city of Bursa, Turkey. The measured radon concentrations ranged from 1.46 to 53.64 Bq l -1 for well water and from 0.91 to 12.58 Bq l -1 for tap water. Of the 27 sites sampled, only 7 had radon levels above the safe limit of 11.1 Bq l -1 recommended by the USEPA. In general, all determined concentrations were well below the 100 Bq l -1 revised reference level proposed by the European Union. These values of radon concentrations in water samples are compared with those reported from other countries. Doses resulting from the consumption of these waters were calculated. The minimum and the maximum annual mean effective doses due to 222Rn intake through water consumption were 0.02 mSv a -1 and 1.11 mSv a -1, respectively. © The Author 2011. Published by Oxford University Press.
Investigation of environmental contamination in lichens of Gökçeada (Imbroz) Island in Turkey
(2009-02-01) Kahraman A.; Kaynak G.; Gurler O.; Yalcin S.; Ozturk S.; Gundogdu O.
The main objective of the present study is to determine the type of environmental contamination in lichens in Gökçeada Island in the Northern Aegean Sea in Turkey. We used two different lichen species Cladonia foliacea and Ramalina pollinaria. In the first part of the investigation, the beta activities of lichens have been measured by using a TENNELEC LB 1000-PW detector. The range of beta activity values was between 607 ± 30 and 308 ± 12 Bq/kg for C. foliacea lichens collected from around Tuz Lake and values for R. pollinaria lichens were found to be 740 ± 25 and 541 ± 17 Bq/kg. The second part of the study was concerned with the gamma spectra of the lichen samples measured by using HpGe detector. 137Cs, 134Cs, 40K, 232Th, 226Ra radionuclides were found in C. foliacea collected from around Tepeköy and in R. pollinaria from around Tuz Lake. When these two types of lichens were compared, it was found that R. pollinaria contain more radionuclides. In order to compare and determine which of these lichens act as a better bioaccumulator, K, Mn, Zn, Rb, Sr, Ba and Pb metal content were determined by using Energy Dispersive X-ray fluorescence spectrometry. It was found that C. foliacea collected more Mn and Sr when compared to R. pollinaria. © 2009 Elsevier Ltd. All rights reserved.
Mass absorption and mass energy transfer coefficients for 0.4-10 MeV gamma rays in elemental solids and gases
(2009-01-01) Gurler O.; Oz H.; Yalcin S.; Gundogdu O.
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature. © 2008 Elsevier Ltd. All rights reserved.
Measurements of radium levels in bottled natural spring water of marmara region (Turkey)
(2012-09-24) Akar U.; Gurler O.; Kahraman A.; Yalcin S.; Kaynak G.; Gundogdu O.
Drinking water may contain varying levels of radioactivity. It is therefore important to determine the radium levels in drinking waters for public health and radiation protection. This paper presents results of 226Ra concentrations in bottled spring waters. The concentration of radium has been assessed in the bottled natural spring water samples commercially available in Turkey. Measurements of 226Ra concentrations in bottled natural spring water samples were carried out by AlphaGUARD, measuring the radon in equilibrium with radium. The radium concentration in these samples is found to be between 0.03 and 0.43 Bq·L-1. These values were compared with the recommended safe limits for drinking water.
Measurements of radon concentration in drinking water samples from Kastamonu (Turkey)
(2011-12-01) Yalcin S.; Gurler O.; Tarim U.A.; Incirci F.; Kaynak G.; Gundogdu O.
Concentration of 222Rn was determined in selected natural spring and tap water samples collected during spring and summer seasons from Kastamonu, Turkey. The aim of this work was to produce a map of the radon concentrations in water sources of the province and to determine any potential radiological risk for the local population. Radon measurements were performed by an AlphaGUARD radon gas analyser. The average radon concentrations were found to vary from 0.39±0.02 to 12.73±0.39 Bq l -1 for natural springs and from 0.36±0.04 to 9.29±0.45 Bq l -1 for tap water in spring, from 0.50±0.09 to 19.21±1.00 Bq l -1 for natural springs and from 0.31±0.03 to 13.14±0.38 Bq l -1 for tap water in summer. Furthermore, the results are compared with international recommendations and concentrations reported for other countries. Doses resulting from the consumption of these waters were calculated. The effective dose equivalents due to the intake of the 222Rn present in these waters are expected to range from 0.93 to 32.54 μSv y -1 in summer and from 0.80 to 49.09 μSv y -1 in spring. © 2011 Copyright Taylor and Francis Group, LLC.
Measurements of radon levels in thermal waters of Bursa, Turkey
(2010-12-01) Gurler O.; Akar U.; Kahraman A.; Yalcin S.; Kaynak G.; Gundogdu O.
Radon (222Rn) is a tasteless, colourless and odourless radioactive noble gas, responsible for approximately 50% of radiation from natural sources. Being highly soluble in water, radon in water sources is also a major public health concern and is still an active research area. This paper presents the results of radon concentration measurements in thermal water samples from Çekirge region of the city of Bursa, rich in geothermal waters located in the northwest part of Turkey. The radon activity concentrations in 36 thermal water samples were determined by using AlphaGUARD PQ 2000PRO radon gas analyser. AlphaGUARD is an ionizing chamber which measures radon via alpha spectrometric techniques. It is found that the concentration ranged from 2.513 + 0.286 to 82.55311.919 Bq·L-1 for radon. The doses delivered to the users during treatment were also calculated and found to be in the range of 0.36 nSv to 11.89 nSv per treatment. © by PSP.
Monte Carlo modelling of single and multiple Compton scattering profiles in a concrete material
(2013-04-01) Akar Tarim U.; Ozmutlu E.; Gurler O.; Yalcin S.; Gundogdu O.; Sharaf J.; Bradley D.
A Monte Carlo simulation study has been conducted of 60Co photons Compton scattered in concrete, illustrating the degraded energy spectra of gamma-ray radiation. Results are produced representing a NaI(Tl) detector model. We were able to analyse energy distributions of photons that reach the detector system after suffering several successive Compton scatterings in the target. The predicted decrease in intensity of single- and multiple-scattering peaks with increase in thickness of the target medium are in good agreement with experimental observations and findings reported by others. © 2012 Elsevier Ltd.
Monte Carlo simulation of gamma-ray total counting efficiency for a Phoswich detector
(2009-01-01) Yalcin S.; Gurler O.; Gundogdu O.; Kaynak G.
The LB 1000-PW detector is mainly used for determining total alpha, beta and gamma activity of low activity natural sources such as water, soil, air filters and any other environmental sources. Detector efficiency needs to be known in order to measure the absolute activity of such samples. This paper presents results on the total gamma counting efficiency of a Phoswich detector from point and disk sources. The directions of photons emitted from the source were determined by Monte Carlo techniques and the true path lengths in the detector were determined by analytical equations depending on photon directions. Results are tabulated for various gamma energies. © 2008 Elsevier Ltd. All rights reserved.
Photon mass energy absorption coefficients from 0.4 MeV to 10 MeV for silicon, carbon, copper and sodium iodide
(2006-07-01) Oz H.; Gurler O.; Gultekin A.; Yalcin S.; Gundogdu O.
The absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy absorption coefficients for gamma rays with an incident energy range between 0.4 MeV and 10 MeV in silicon, carbon, copper and sodium iodide. The mass energy absorption coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
The energy spectrum of 662keV photons in a water equivalent phantom
(2012-01-01) Akar Tarim U.; Gurler O.; Ozmutlu E.; Yalcin S.; Gundogdu O.; Sharaf J.; Bradley D.
Investigation is made on the energy spectrum of photons originating from interactions of 662. keV primary gamma-ray photons emitted by a point source positioned at the centre of a water equivalent solid phantom of dimensions 19. cm×19. cm×24. cm. Peaks resulting from total energy loss (photopeak) and multiple and back scattering have been observed using a 51. mm×51. mm NaI(Tl) detector; good agreement being found between the measured and simulated response functions. The energy spectrum of the gamma photons obtained through the Monte Carlo simulation reveals local maxima at about 100. keV and 210. keV, being also observed in the experimental response function. Such spectra can be used as a method of testing the water equivalence of solid phantom media before their use for dosimetry measurements. © 2012 Elsevier Ltd.