Radionuclide Metrology Techniques Session Posters

A MODIFIED METHOD FOR THE CHARACTERISATION AND ACTIVITY DETERMINATION OF LARGE AREA SOURCES A.Švec (a), H.Janßen (b), L.Pernická (a), R.Klein (b) (a) Slovak Institute of Metrology (b) PTBA MODIFIED METHOD FOR THE CHARACTERISATION AND ACTIVITY DETERMINATION OF LARGE AREA SOURCES A.Švec (a), H.Janßen (b), L.Pernická (a), R.Klein (b) (a) Slovak Institute of Metrology (b) PTB Absorption, auto-absorption and backscattering in large area source active layers cause known difficulties in their activity determination through direct measurements. Absorption, auto-absorption and backscattering in large area source active layers cause known difficulties in their activity determination through direct measurements. Discovered a correlation between the efficiency and a characteristic source parameter related to the absorption in air. Discovered a correlation between the efficiency and a characteristic source parameter related to the absorption in air. characteristic parameter is derived from a set of measurements in equidistant source positions from a large area detector. characteristic parameter is derived from a set of measurements in equidistant source positions from a large area detector. After calibrations with certified and homogeneous standard sources, the instrument and the method enable the determination of efficiency values corrected for absorption and auto-absorption. After calibrations with certified and homogeneous standard sources, the instrument and the method enable the determination of efficiency values corrected for absorption and auto-absorption. The procedure works equally well for alpha and beta sources. The procedure works equally well for alpha and beta sources. P-007

Response calculation for standard ionization chambers in APMP using EGS4 Monte Carlo code Yasushi Sato (a), Akira Yunoki (a), Yoshio Hino (a), Takahiro Yamada (b) (a) NMIJ, Japan, (b) JRA, Japan Comparisons aimed at improving the calibration factors of ionization chambers used as secondary standards within the APMP region ( 51 Cr, 57 Co, 60 Co, 137 Cs and 139 Ce). Comparisons aimed at improving the calibration factors of ionization chambers used as secondary standards within the APMP region ( 51 Cr, 57 Co, 60 Co, 137 Cs and 139 Ce). The calibration factors for IG11 chambers showed good agreement in high energy region (from 51 Cr to 60 Co). The calibration factors for IG11 chambers showed good agreement in high energy region (from 51 Cr to 60 Co). Calibration factor ratios vary significantly in the low energy region (from 57 Co to 51 Cr) for the same IG11 chamber types. Calibration factor ratios vary significantly in the low energy region (from 57 Co to 51 Cr) for the same IG11 chamber types. To explain such tendencies, Monte Carlo calculations using the EGS4 code were employed (down to 1 keV photon energy). To explain such tendencies, Monte Carlo calculations using the EGS4 code were employed (down to 1 keV photon energy). Monte Carlo calculations do not yet explain fully the differences in reported calibration factors, but showed the degree of effect was due wall thickness of well, sample holder material and counting gas. Monte Carlo calculations do not yet explain fully the differences in reported calibration factors, but showed the degree of effect was due wall thickness of well, sample holder material and counting gas. P-049

Random-summing correction and pile-up rejection in the sum-peak method M. Capogni, A. Ceccatelli, P. De Felice, A. Fazio ENEA-INMRI Standardization of 125 I by Sum Peak Counting with 2 well–type NaI(Tl) detectors. Standardization of 125 I by Sum Peak Counting with 2 well–type NaI(Tl) detectors. Measurement of Single and Coincident Event peak count rates (A I and A II ), using 5 different pulse recording systems. Measurement of Single and Coincident Event peak count rates (A I and A II ), using 5 different pulse recording systems. Random summing effects with respect to the use of pile-up rejection and live time correction circuits are investigated. Random summing effects with respect to the use of pile-up rejection and live time correction circuits are investigated. Activity concentration was calculated and reported as function of the A II count rate, and extrapolated to A II =0 yielding a value of activity concentration corrected for random-summing and dead-time losses. Activity concentration was calculated and reported as function of the A II count rate, and extrapolated to A II =0 yielding a value of activity concentration corrected for random-summing and dead-time losses. Theoretical model, based on Poisson statistics, was proposed to explain the experimental data. The rate of pile-up losses and dead- time losses for both energy regions I and II and for the spectrometric and SCA systems were estimated. Theoretical model, based on Poisson statistics, was proposed to explain the experimental data. The rate of pile-up losses and dead- time losses for both energy regions I and II and for the spectrometric and SCA systems were estimated. Good agreement between the simulated and experimental data was observed. Good agreement between the simulated and experimental data was observed. P-057

Standardisation of 54 Mn and 65 Zn using software coincidence counting system Miroslav Havelka*, Pavel Auerbach, Jana Sochorová CMI 4 (PC) - coincidence efficiency extrapolation with the beta efficiency variation made 4 (PC) - coincidence efficiency extrapolation with the beta efficiency variation made - by computer discrimination - by computer discrimination - by source self-absorption - by source self-absorption For 65 Zn standardisation, discusses a procedure for optimal - ray energy window setting based on beta and coincident beta spectral analysis. For 65 Zn standardisation, discusses a procedure for optimal - ray energy window setting based on beta and coincident beta spectral analysis. Shows the benefits of SCC approach … easily adjust coincidence counting parameters Shows the benefits of SCC approach … easily adjust coincidence counting parameters Comparison with classical coincidence measurements. Comparison with classical coincidence measurements. P-064

Standardisation of 241 Am solution M.Koskinas, E. Silva, I. Yamazaki, M. Dias IPEN-CNEN/SP The standardization of 241 Am by the Laboratório de Metrologia Nuclear (LMN) at the IPEN, in São Paulo The standardization of 241 Am by the Laboratório de Metrologia Nuclear (LMN) at the IPEN, in São Paulo The activity measurement was carried out in a 4 (PC) - coincidence system. The 4 proportional counter used for alpha detection has a 0.1 mm thick Al window in the outside wall in order to minimize -ray attenuation. The activity measurement was carried out in a 4 (PC) - coincidence system. The 4 proportional counter used for alpha detection has a 0.1 mm thick Al window in the outside wall in order to minimize -ray attenuation. Extrapolation technique was employed to determine the activity of the solution. The efficiency was changed by two different methods: addition of external absorbers and electronic threshold of alpha spectrum. Extrapolation technique was employed to determine the activity of the solution. The efficiency was changed by two different methods: addition of external absorbers and electronic threshold of alpha spectrum. The events were registered using a Time to Amplitude Converter (TAC) associated with a Multichannel Analyser. The events were registered using a Time to Amplitude Converter (TAC) associated with a Multichannel Analyser. Discussion of uncertainties. Discussion of uncertainties. P-104

Standardization of 152 Eu and 154 Eu by 4 β-4 coincidence method and 4 (β+ ) integral counting T. Yamada a, Y. Nakamura a, Y. Kawada a, Y. Sato b and Y. Hino b a JRA, Japan, b NMIJ, Japan 4 β-4 configuration : 4 β-4 configuration : (4 ) : two 20mm 2 * 1mm plastic scintillation sheets, sandwiched around source. Source assembly inserted in : (4 ) : two 20mm 2 * 1mm plastic scintillation sheets, sandwiched around source. Source assembly inserted in : (4 NaI(Tl) well detector. (4 NaI(Tl) well detector. 4 β-4 coincidence counting : (3 different gamma gates). 4 β-4 coincidence counting : (3 different gamma gates). 152 Eu : 154 Eu impurity (0.85%) 154 Eu : 152 Eu (9%) and 155 Eu(3%) impurities. (Plan to repeat with a pure solution) 4 β sum counting : 4 β sum counting : Inefficiency variation by EGS4 simulation and threshold variation Good agreement between methods. Good agreement between methods. P-108

Standardisation of 99m Tc M. Sahagia IFIN-HH, Romania 4 PC- coincidence method (three measurement variants) 4 PC- coincidence method (three measurement variants) Coincidences between (119.5 – 142.6) keV conversion electrons and KX-rays Coincidences between (119.5 – 142.6) keV conversion electrons and KX-rays Coincidences between 2.13 keV conversion electrons and keV –rays (in two variants) Coincidences between 2.13 keV conversion electrons and keV –rays (in two variants) Corrections Corrections Compton Background of K X-ray peak Compton Background of K X-ray peak Sensitivity of P.C. to keV rays Sensitivity of P.C. to keV rays Efficiency Extrapolations Efficiency Extrapolations General coincidence equations were written, with specific forms, for the three measurement variants General coincidence equations were written, with specific forms, for the three measurement variants Comparison with the ionization chamber calibration Comparison with the ionization chamber calibration P-111