Simultaneous determination of60Co,131I and137Cs in model radioactive waste water by reverse radiometric flow injection analysis with the aid of a multichannel analyzer

Reverse radiometric flow injection analysis was used for the simultaneous determination of⁶⁰Co,¹³¹I and¹³⁷Cs in model radioactive waste water. A NaI (Tl) scintillation detector coupled to a Canberra MCA was used for measuring the activity of¹³⁷Cs at 662 keV,⁶⁰Co at 1173 keV and 1332 keV, and¹³¹I at 364 keV.     

Determination of Co and Cs by stopped-flow RFIA with the aid of multi-channel analyzer

Radiometric flow-injection analysis (RFIA) was used for the transport of carrier and sample solution. Radioactive nuclides⁶⁰Co and¹³⁷Cs were used as indicators and a NaI (Tl) scintillation detector coupled to a Canberra MCA for measuring the activity of¹³⁷Cs at 662 keV and⁶⁰Co at 1173 keV and 1332 keV. Experimental parameters related to RFIA were studied, too.     

Correction equations of coincidence summing using75Se radionuclide in the efficiency of HpGe detector

Correction equations of the coincidence-summing effect for efficiencies of HpGe detector based on the decay scheme were developed by considering the summing up to triple coincidence. The correction equations which do not dependent on the kind of the Ge detector are very useful for efficiency calibrations of a Ge detector in the energy region from 60 to 400 keV by using⁷⁵Se radionuclide even with very short source-to-detector distances.     

Radionuclide purity assessment and calibration of <Superscript>90</Superscript>Y(<Superscript>177</Superscript>Lu) glass particles using gamma-ray spectrometry

Intra-hepatic administration of radioactive glass microspheres is a treatment for patients with primary liver cancer and hepatic metastases. The purpose of this study was radionuclide purity assessment of new glass particles containing two radionuclide, ⁹⁰Y as a therapeutic source and also ¹⁷⁷Lu as a source of diagnostic gamma. For the mixed source, activity measurement using a dose calibrator cannot be used and we need new calibration methods. YAS (Yb) and YAS compositions were sol–gel derived glass particles and production of ⁹⁰Y (¹⁷⁷Lu) and ⁹⁰Y particles was performed using the Tehran Research Reactor. The radionuclide purity was carried out using γ-spectrometry with HPGe detector. A non-destructive spectroscopic assay was employed due to a newly updated low uncertainty positron branching ratio of ⁹⁰Y that emit 511 keV annihilation radiations. In another method, a new calibration of ⁹⁰Y using a non-destructive spectroscopic assay of ⁸⁸Y were investigated. Potential radionuclide impurity include: ⁸⁸Y, ¹⁵²Eu, ⁶⁰Co with activity 100, 50 and 5 Bq per 1 mg of that are not harmful for patients due to delivering radioactive particles about 20–50 mg in ⁹⁰Y(¹⁷⁷Lu) glass microspheres. Among of radionuclide impurity, ¹⁵²Er with a half life of 13.54 years and ⁸⁸Y with a half life of 106.65 days was important in the residual delivery device. For calibration of ⁹⁰Y with monitoring of 511 keV, errors were12.2–21%. In calibration of ⁹⁰Y using gamma spectroscopic assay of ⁸⁸Y, there was an error less than 14%. Spectroscopic assay of ⁸⁸Y can be performed easily and has more repeat for our purpose.     

Validation testing of the Genie 2000 Cascade Summing Correction

Summary To validate the accuracy and precision of the Cascade Summing Correction method, over 800 archived measurements of calibrated sources (filter paper, 20 cm³ liquid scintillation vial, 400 ml beaker and Marinelli beaker) containing cascading (⁸⁸Y and ⁶⁰Co) and non-cascading isotopes from 133 different ISOCS/LabSOCS characterized high purity germanium detectors have been analyzed. Comparing the corrected results for the cascading isotope activities to the known activities shows the method is effective and accurate. Evaluation of the accuracy as a function of the amount of correction reveals a small systematic error for which a variable precision adjustment is recommended. Requirements to filter true coincidence X-rays by are verified.     

Calculation of peak-to-total ratios for high purity germanium detectors using Monte-Carlo modeling

Summary In order to estimate by calculation the magnitude of the true coincidence summing losses that may be affecting the observed gamma-ray spectrum of a given nuclide, measured using a spectrometer, knowledge of the total detection efficiencies at the gamma-ray energies within the cascades is essential. The total efficiency can be determined from the full energy peak efficiency, provided the peak-to-total ratio is known. For a given high purity germanium (HPGe) detector, one can establish an intrinsic peak-to-total (P/T) efficiency curve using a set of measurements performed with “single” (ideally monoenergetic) gamma-emitting nuclides (e.g., ²⁴¹Am, ¹⁰⁹Cd, ⁵⁷Co, ¹¹³Sn, ¹³⁷Cs, ⁶⁵Zn). Some of these nuclides are short lived and so have to be replaced periodically. Moreover, the presence of low energy gamma-rays and X-rays in most of the decay schemes complicate the empirical determination of the P/T ratios. This problem is especially severe if measurements are made using HPGe detectors that have a very thin dead layer. The problems posed by low energy gamma-rays and X-rays can be avoided by using absorbers, but then one has to be careful not to perturb the intrinsic value of the P/T ratio being sought. This paper addresses these problems. Measurement related limitations are avoided if one can use a computational technique instead. In the work presented here, the feasibility of using a Monte-Carlo based technique to determine the P/T ratios at a wide range of energies (60 keV to 2000 keV) is explored. The Monte-Carlo code MCNP (version 4B) is used to simulate gamma-ray spectra from various nuclides. Measured P/T ratios are compared to calculated ratios for several HPGe detectors to demonstrate the generality of the approach. Reasons for observed disagreement between the two are discussed.     

Efficiency calibration of HPGe detector in far and close geometries

The absolute total and full-energy peak (FEP) efficiencies of a high purity germanium (HPGe) photon detector are measured in the energy range from 40 keV to 1500 keV. The functional parameters are fitted to the calibration points from 14 long-lived standard sources (¹²⁹I,²⁴¹Am,¹⁰⁹Cd,⁵⁷Co,¹³⁹Ce,¹³⁷Cs,⁵⁴Mn,⁶⁵Zn,⁶⁰Co,²²Na,¹³³Ba,¹⁵²Eu,¹⁵⁴Eu and^166mHo) within an accuracy better than the quoted uncertainty of the calibration sources. The efficiencies in far and close geometries are compared.     

True coincidence summing corrections in point and extended sources

The true coincidence summing (TCS) effect on the full energy peak (FEP) efficiency calibration of an HPGe detector has been studied as a function of sample-to-detector distance using multi-gamma sources. Analytical method has been used to calculate coincidence correction factors for ¹⁵²Eu, ¹³³Ba, ¹³⁴Cs and ⁶⁰Co for point and extended source geometry at close sample-to-detector distance. Peak and total efficiencies required for this method have been obtained by using MCNP code by using the optimized detector geometry. The correction factors have also been obtained experimentally. The analytical and the experimental correction factors have been found to match within 1–5%. The method has been applied to obtain the activity of the radionuclides (¹⁰⁶Ru, ¹²⁵Sb, ¹³⁴Cs and ¹⁴⁴Ce) present in a fission product sample.     

True coincidence summing correction determination for 214Bi principal gamma lines in NORM samples

The gamma lines 609.3 and 1,120.3 keV are two of the most intensive γ emissions of ²¹⁴Bi, but they have serious true coincidence summing (TCS) effects due to the complex decay schemes with multi-cascading transitions. TCS effects cause inaccurate count rate and hence erroneous results. A simple and easy experimental method for determination of TCS correction of ²¹⁴Bi gamma lines was developed in this work using naturally occurring radioactive material samples. Height efficiency and self attenuation corrections were determined as well. The developed method has been formulated theoretically and validated experimentally. The corrections problems were solved simply with neither additional standard source nor simulation skills.     

The measurement of neutron-induced radionuclides from Chinese nuclear weapons tests

The concentrations of neutron-induced radionuclides have been measured in ground level air during the period between 1976 and 1981 at Nagoya (35° N, 137° E), Japan. Six Chinese atmospheric nuclear weapons tests were conducted by the government of China at Lop Nor (40° N, 90° E) during the period 1976–1981. The Chinese nuclear tests of November 17, 1976 (the 21st test) and October 16, 1980 (the 26th test), high-yield devices, produced⁵⁴Mn,⁵⁵Fe and⁸⁸Y whose production reactions are⁵⁴Fe(n, p),⁵⁶Fe(n, 2n) and⁸⁹Y(n, 2n), respectively. The tests of September 26, 1976 (the 19th test), September 17, 1977 (the 22nd test) and March 15, 1978 (the 23rd test), low-yield devices, produced⁵⁴Mn,⁵⁷Co and⁵⁸Co whose production reactions are⁵⁴Fe(n, p),⁵⁸Ni(n, pn) and⁵⁸Ni(n, p) respectively. No neutron activation product from the 24th test (December 14, 1978) was observed.     

Measurement of radioactive samples in Marinelli beakers by gamma-ray spectrometry

Radioactivity measurement of environmental samples is frequently assayed by gamma-ray spectrometry using Marinelli beakers. In this work, self-absorption and coincidence summing effects arising in activity measurements for Marinelli beaker geometry have been studied with a Ge detector. Three types of Marinelli beakers which have capacities of 450 mL, 1 L, and 2 L were developed. Self-attenuation effects for density variation of radioactive samples in each type of the Marinelli beakers were measured as a function of gamma-ray energy, and also the results were compared with calculated values by mathematical model. Meanwhile, the coincidence summing effects of¹²⁵Sb and¹⁵⁴Eu nuclides were obtained from the determination of the full-energy peak and total efficiencies for a Ge detector.     

Etude des generateurs de strontium-87m

A method is proposed for the determination of chemical and radionuclidic purity of^87mSr generator eluates. Two generators of different origins have been studied. The presence of the radionuclides⁸⁷Y,⁸⁵Sr,⁸⁸Y,⁶⁰Co,⁵⁸Co has been shown in the eluates. Fe and Sr were not found in the eluates in concentrations higher than 10 mg/l and 100 mg/l, respectively. A recommendation is made for the use of these generators.      

Sum peak in gamma-energy spectra of NaI(T1) detectors

The factors affecting the sum peak of NaI(T1) detectors has been studied experimentally, namely the intrinsic photopeak efficiency, the geometry factor, the energy and the intensity of the incident photon beam. Several radioactive sources were used for the measurement of the intrinsic photopeak efficiency of the two NaI(T1) detectors used in this work (51 mm × 51 mm and 76 mm × 76 mm).⁸⁸Y,⁶⁰Co and²²Na, were used for sum peak determination. Different source to detector distances, to produce different values of geometry factor, and different source activities were used. The effect of geometry on the intrinsic photopeak efficiency is very pronounced at high geometry factor. The linear relation between the relative intensity of the sum peak and both the geometry factor and the intensity of the incident photons, facilitate the quantitative prediction of the sum effect on the energy response function of NaI(T1) detectors.     

Activation cross-sections for some (n, 2n), (n,p) and (n, γ)-reactions

The average fission neutron cross-sections of the reactions²³³U(n, 2n)²³²U,⁶⁰Ni(n, p)⁶⁰Co and²⁷Al(n, p)²⁷Mg and the resonance integrals of the (n, γ)-reactions of the nuclides¹⁸¹Ta,¹⁷⁶Lu,¹⁷⁵Lu,⁶⁴Ni,⁵⁹Co and²⁶Mg have been determined by the activation method following the well-known conventions. The results verify some of the existing values and present data for hitherto unknown or poorly known reactions.     

Study of (α, 2α xn) and (α, 4pxn) reaction on natural copper

A stack of natural copper was bombarded with 85 MeV alpha particles. Cumulative cross sections for the production of⁵⁶Co,⁵⁷Co,^58(m+g)Co and^60(m+g)Co have been studied using gamma-ray spectroscopy.     

Modified and reverse radiometric flow injection analysis

Determination of¹³⁷Cs and⁶⁰Co by using modified and reverse radiometric flow injection analysis is described. Two component RFIA was also realized using⁶⁰Co and¹³⁷Cs radionuclides.     

The relative sensitivity and accuracy of NaI(Tl) and Ge(Li) detectors for minor components

A mixture of²³³Pa,¹⁴⁰La,⁸²Br,⁶⁴Cu.⁷²Ga,⁶⁰Co, and²⁴Na of known disintegration rates was counted on a NaI(Tl) and a large Ge(Li) detector. Both systems detected²³³Pa when present at 0.2%, and accurate results were observed for²³³Pa,¹⁴⁰La, and⁶⁰Co when present at greater than 0.5% of the total disintegration rate. The accuracy of the results from either system was not significantly different since the mean ratio of the observed to true results was 0.99±0.05 and 1.06±0.06, respectively. However, equal sensitivity and accuracy were achieved only when the counting interval for the germanium system was 1000 min, or 60 to 600 times that for sodium iodide.     

Short-lived chemical species of57Fe in57Co-labelled Co/IO3/2 studied by time-resolved emission Mössbauer spectroscopy

Time resolved Mössbauer spectra were measured for⁵⁷Co-labelled Co/IO₃/₂ using a delayed coincidence technique. A life-time for unstable⁵⁷Fe(II)-species formed through EC-decay was estimated to be 43±5 ns at room temperature and the initial distribution of⁵⁷Fe(II)/⁵⁷Fe(III) at 14.4 keV nuclear level to be 0.47±0.13. The results are discussed in terms of electron transfer from the decayed⁵⁷Fe(II) atoms to iodate ions.     

(E, E)S, S′-bis(2-benzimidazolylmethyl) dithioglyoxime, synthesis and characterization of heterotrinuclear complexes of and determination of their metal contents by EDXRF analysis

A vicinal dioxime ligand with two 2-benzimidazolylmethyl groups, namely S, S′-bis(2-benzimidazolylmethyl) dithioglyoxine (H₂L) and its axially pyridine and 2,6-dimethyl pyridine bonded Co(III) complexes were prepared according to prior literature [Y. Gök, S.Z. Y?ld?z, Synth. React. Inorg. Met-Org. Chem. 22 (9) (1992) 1327]. BF₂⁺ bridged Co(III) complexes have been synthesized via the hydrogen-bridged Co(III) complexes by using borontrifloride ethyl ether complex. Heterotrinuclear complexes have been prepared by the reaction of these more soluble BF₂-capped Co(III) complexes with stoichiometric amount of CdCl₂ · H₂O and NiCl₂ · 6H₂O salts. Using ¹H, ¹³C NMR, IR and MS spectral data and elemental analysis, the structures of the complexes were identified. Qualitative and quantitative determination of Co, Ni and Cd contents of the heterotrinuclear complexes have been investigated by energy dispersive X-ray fluorescence (EDXRF) method. An annular 50 mCi ²⁴¹Am radioactive source emitting 59.543 keV photons was used for excitation and Si(Li) detector having 157 eV FWHM at 5.9 keV was used for intensity measurements.     

Total versus effective total efficiency in the computation of coincidence summing corrections in gamma-ray spectrometry of volume sources

For the evaluation of coincidence summing effects for volume sources an effective total efficiency (ETE) is used instead of the common total efficiency (TE). In this paper ETE is computed by the Monte Carlo method. The differences between ETE and TE are analyzed and their origin is discussed. Measured values for the coincidence summing correction factors for a standard solution containing ¹⁵²Eu in a one liter Marinelli beaker are compared with computed values obtained from appropriate values of ETE. It is shown that the procedure for the evaluation of the coincidence effects is reliable. As a consequence it can be concluded that ¹⁵²Eu volume sources can be successfully used for efficiency calibration even in the case of high-efficiency detectors and close source-to-detector distances.