T Altzitzoglou

European Commission - Joint Research Centre, Brussels, BRU, Belgium

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Publications (61)71.23 Total impact

  • Metrologia 01/2014; 51. · 1.90 Impact Factor
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    ABSTRACT: Two new participations in the comparison BIPM.RI(II)-K1.Lu-177 have been added to the previous results and this has produced a revised value for the key comparison reference value (KCRV), calculated using the power-moderated weighted mean. A link has been made to the comparison CCRI(II)-K2.Lu-177 held in 2009 through the NPL and IRMM who participated in both comparisons. Two NMIs used the K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining two NMIs in the comparison BIPM.RI(II)-K1.Lu-177 and the nine other participants in the comparison CCRI(II)-K2.Lu-177. A graphical presentation is also given.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
    12/2013; 51(1A).
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    ABSTRACT: In this work, excitation functions for deuteron-induced reactions on natural hafnium have been measured in the energy range 7–17 MeV, using the stacked-foil technique. Particular attention has been paid to the reaction natHf(d,x)177Ta, because reported γ-ray intensities have been found to be in disagreement with previously published data. This discrepancy is due to an error in the 2003 ENSDF absolute γ-ray intensities of 177Hf following the decay of 177Ta, which are about a factor of three higher compared to other available data. As a consquence, some peer reviewed papers reporting on natHf(d,x)177Ta, and also on natHf(p,x) 177Ta and natW(p,x) 177Ta, need to be reviewed. An upcoming re-evaluation of the 177Ta decay data shows new significant changes in the absolute γ-ray intensities, which in turn will affect again the 177Ta producing cross sections.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 08/2012; 285:162–164. · 1.27 Impact Factor
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    ABSTRACT: The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of (152)Eu and (134)Cs, and different source-to-detector distances. They are presented and discussed.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 03/2012; 70(9):2112-8. · 1.09 Impact Factor
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    ABSTRACT: An international Key Comparison of (177)Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of (177)Lu, leading to eleven results submitted for entry into the Key Comparison Database of the Mutual Recognition Arrangement. A proposed Comparison Reference Value (CRV) was calculated to be 3.288(4)MBq/g using all eleven results. Degrees of equivalence and their uncertainties were calculated for each laboratory based on the CRV. Most of the values reported by the participating laboratories were within 0.6% of the CRV.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 03/2012; 70(9):1825-30. · 1.09 Impact Factor
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    ABSTRACT: The (230)U half-life was determined by measuring the decay curve of (230)U sources by various nuclear detection techniques: α-particle counting at a defined small solid angle; 4πα+β counting with a windowless CsI sandwich spectrometer, a liquid scintillation counter and a pressurised proportional counter; gamma-ray spectrometry with a HPGe detector and nearly-2π α-particle counting with an ion-implanted silicon detector. Depending on the technique, the decay was followed for 100-200 d, which is 5-10 times the (230)U half-life. The measurement results of the various techniques were in good mutual agreement. The mean value, T(1/2)((230)U)=20.23 (2) d, is lower than the literature value which is based on one measurement in 1948 and resulted in a half-life value of 20.8d without statement of uncertainty. A correction for the ingrowth of the long-lived (210)Pb and its daughter products may have been overlooked in the past.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 03/2012; 70(9):1900-6. · 1.09 Impact Factor
  • J Merešová, U Wätjen, T Altzitzoglou
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    ABSTRACT: A comparison was organised by the Institute for Reference Materials and Measurements (IRMM) among 73 environmental radioactivity monitoring laboratories for the determination of 15 radionuclides in soil. The reference material IAEA-375 soil was reprocessed to provide the comparison material and reference values traceable to SI units and SIR were established at IRMM. The analytical procedures used by participants laboratories are discussed and performances evaluted using relative deviations and E(n) numbers. This paper focuses on the results for (40)K, (90)Sr, (137)Cs, (226)Ra, (234)U, (235)U and (238)U. Worst performance was found for (90)Sr and (235)U, where 65% and 78% of the results, respectively, deviate more than 20% from the reference values. The use of the E(n) criterion revealed that the uncertainty estimation of many participants is poor.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 02/2012; 70(9):1836-42. · 1.09 Impact Factor
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    ABSTRACT: Radioactivity found in wild food products has assumed greater importance when assessing the total exposure of the population. For this reason, IRMM has been developing a reference material for the activity concentration of three radionuclides in bilberry samples. In order to characterise this new material, a CCRI(II) supplementary comparison was organised. The difficulties encountered in this comparison are discussed, in particular the efficiency calibration for volume sources of gamma-ray emitters, and comparison reference values for (137)Cs and (40)K are calculated.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 02/2012; 70(9):1843-9. · 1.09 Impact Factor
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    ABSTRACT: The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of 152Eu and 134Cs, and different source-to-detector distances. They are presented and discussed
    Applied Radiation and Isotopes 01/2012; 70:2112-2118. · 1.18 Impact Factor
  • S Pommé, J Paepen, T Altzitzoglou, R Van Ammel, E Yeltepe
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    ABSTRACT: The half-life of (177)Lu was measured by following the decay of sources with an ionisation chamber and with a liquid scintillation counter over a period of 85 and 42 days, respectively. The detector signals showed three major components: decay of (177)Lu, decay of (177m)Lu and the background signal. The half-life value, T(1/2)((177)Lu)=6.6465 (50)d, was obtained by a least-squares fit of two exponential decay functions and a constant background to the experimental data. The data was corrected for decay during the measurements. Residuals of the fit and uncertainty budgets are presented in this paper. The result is in agreement with three out of seven previously published measurement results and the currently recommended value of 6.647 (4) d (Kondev, 2002). A new value of T(1/2)((177)Lu)=6.6465 (32) d was obtained from a weighted mean of our results with the selected literature data.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 09/2011; 69(9):1267-73. · 1.09 Impact Factor
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    ABSTRACT: A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of 152Eu and 134Cs, and three source-to-detector distances. They are presented and discussed.
    Applied Radiation and Isotopes 07/2010; 68(7-8):1407-1412. · 1.18 Impact Factor
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    ABSTRACT: Sources of enriched (240)Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of (240)Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from gamma-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while gamma-ray spectrometry confirms that its intensity is much lower than expected from literature.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 07/2010; 68(7-8):1459-66; discussion 1466. · 1.09 Impact Factor
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    ABSTRACT: An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories. In order to identify possible biases, the participants were asked to use all possible activity measurement methods available in their laboratory and then to determine their reference value for comparison. Thus, measurement results from 4pibeta-gamma coincidence/anti-coincidence counting, CIEMAT/NIST liquid-scintillation counting, 4pigamma counting with well-type ionization chambers and well-type crystal detectors were given. The results are compared and show a maximum discrepancy of about 1.6%: possible explanations are proposed.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 02/2010; 68(7-8):1207-10. · 1.09 Impact Factor
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    ABSTRACT: An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories, six of which sent results for photon emission intensities both in absolute and in relative terms. From these results and including previous published values, a consistent decay scheme was worked out, proving that problems in activity measurements have not been due to decay scheme data.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 02/2010; 68(10):2026-30. · 1.09 Impact Factor
  • J Paepen, T Altzitzoglou, R Van Ammel, G Sibbens, S Pommé
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    ABSTRACT: The half-life of (124)Sb was determined experimentally by following the decay of a source from a radiopure solution with a Centronic IG12 ionisation chamber. Thousands of measurements were performed over a period of 358 days, i.e. about six half-life periods. However, the data analysis was restricted to the first 221 days, in order to limit the dominant uncertainty component associated with the hypothetical possibility of a systematic error on background subtraction. The resulting value for the (124)Sb half-life, 60.212 (11) days, is found to be in very good agreement with published values, but carries a lower uncertainty. Major uncertainty contributions pertain to possible systematic errors in background correction, long-term changes in source-detector geometry and medium- and long-term instability of the instrument. Additional measurements were performed with a high-purity germanium detector to confirm the above value.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 01/2010; 68(7-8):1555-60; discussion 1560. · 1.09 Impact Factor
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    ABSTRACT: A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of 152Eu and 134Cs, and three source-to-detector distances. They are presented and discussed.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 01/2010; · 1.09 Impact Factor
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    ABSTRACT: A comparison exercise for data analysis was recently conducted by the Liquid Scintillation Counting Working Group (LSCWG) of the International Committee on Radionuclide Metrology (ICRM) to evaluate the uncertainties involved in applying different analysis methodologies (including computer programs) for the triple-to-double coincidence ratio (TDCR) method. The goals of the comparison were to (1) study differences in calculation results from different TDCR analysis programs, (2) investigate differences in analysis techniques and uncertainty assessment philosophies between laboratories, and (3) study the effect of not taking asymmetry of photomultiplier tube (PMT) efficiencies into account on the calculated activity. To achieve this, a single set of TDCR data for the pure beta emitter (99)Tc, was distributed to the participants, who analyzed the data according to their normal procedures and report the activity concentration of the (99)Tc solution from their results. The results indicate that the presently used programs are generally able to calculate the same activity values, assuming that the correct input parameters are used and that not taking PMT asymmetry into account in the calculations can lead to significant (0.6% for (99)Tc) errors in reported results. The comparison also highlighted the need for a more rigorous approach to estimating and reporting uncertainties.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 12/2009; 68(7-8):1477-81. · 1.09 Impact Factor
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    ABSTRACT: A comparison of different radiochemical separation procedures and measurement techniques used to determine the activity concentration of (226)Ra and (228)Ra in water is made with respect to accuracy, detection limits and turn-around time. Radium-226 activity concentration was determined by the radon emanation technique, alpha-particle and gamma-ray spectrometry. To determine the (228)Ra activity concentration, four different techniques were used: low-level liquid scintillation counting, low-level proportional counting, alpha-particle and low-level gamma-ray spectrometry.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 11/2009; 68(7-8):1236-9. · 1.09 Impact Factor
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    ABSTRACT: In anticipation of new European requirements for monitoring radioactivity concentration in drinking water, IRMM organized an interlaboratory comparison on the determination of low levels of activity concentrations (about 10-100 mBq L(-1)) of the naturally occurring radionuclides (226)Ra, (228)Ra, (234)U and (238)U in three commercially available mineral waters. Using two or three different methods with traceability to the International System of Reference (SIR), the reference values of the water samples were determined prior to the proficiency test within combined standard uncertainties of the order of 3%-10%. An overview of radiochemical separation and measurement methods used by the 45 participating laboratories are given. The results of the participants are evaluated versus the reference values. Several of the participants' results deviate by more than a factor of two from the reference values, in particular for the radium isotopes. Such erroneous analysis results may lead to a crucial omission of remedial actions on drinking water supplies or to economic loss by an unjustified action.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 11/2009; 68(7-8):1200-5; discussion 1205-6. · 1.09 Impact Factor
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    ABSTRACT: The half-life of 233U was determined by a specific activity method, in the frame of an international collaboration project of four metrology institutes. A purified, highly enriched 233U solution was prepared with certified concentration of uranium isotopes. The isotopic composition of the uranium material was determined by thermal ionization mass spectrometry. The ingrowth of daughter nuclides was calculated and confirmed by α-particle and γ-ray spectrometry measurements. Quantitative sources were prepared from aliquots of the 233U solution and their disintegration rate was determined by means of α-particle counting at a defined small solid angle, liquid-scintillation counting and 4π counting in a pressurized proportional counter and in a CsI(Tl) sandwich spectrometer. A half-life value of 1.5867 (14) × 105 a was obtained, in which the relative standard uncertainty amounts to 0.09%. The result is lower than the currently recommended value of 1.592 (2) × 105 a and a new best estimate of T1/2(233U) = 1.5903 (13) × 105 a was calculated from a partially weighted mean of a set of published data.
    Metrologia 06/2009; 46(5):439. · 1.90 Impact Factor