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[en] The Technical Committee for Ionizing Radiation (TCRI) of the Asia Pacific Metrology Programme (APMP) recently organized a regional key comparison of activity measurements of the radionuclide 133Ba. This paper reports on absolute measurements made at the National Metrology Institute of South Africa (NMISA) by the coincidence extrapolation technique, with liquid scintillation counting (LSC) comprising the 4π channel. A detection efficiency analysis was undertaken to predict the maximum efficiency likely to be achieved and to confirm that the method does indeed provide the source disintegration rate for 133Ba. Various experimental and data analysis difficulties to be aware of are discussed in the paper
[en] A method for the attachment of cryptates containing radioactive metal ions to proteins has been developed. The aminocryptand, 4,7,13,16,21,24-hexaoxa-5,6-(4'-aminobenzo)1,10-diazabicyclo[8.8.8 ]-hexacosane, was complexed with divalent 133Ba and subsequently converted to the isothiocyanatocryptate. The bioconjugate with immunoglobulin G was formed in better than 40% radiochemical yield in a three step procedure. Alternatively, the radiolabeled bioconjugate could be formed by addition of 133Ba to immunoglobulin G that has been reacted with the isothiocyanate derivative of the cryptand. Stability studies indicated the radiolabeled bioconjugate has a half-life of 6 h and 12 h in phosphate buffers of pH=7.4 and pH=9.2, respectively. Attempts to label the immunoglobulin with the corresponding 142Pr cryptate resulted in considerable radioactive colloid formation with no detectable bioconjugate produced. (author)
[en] The transmitted photon spectra of 133Ba gamma rays have been recorded and studied as a function of dimensions of a soil medium. In these studies a multiple-scatter peak is observed in the soft part of the spectrum. The longitudinal thickness of the soil medium is seen to affect only the intensity of the peak, whereas the variation in transverse thickness affects both the intensity and energy of the peak. A reversal of the trend of the multiple-scatter peak intensity to increase with transverse thickness occurs as the longitudinal dimension increases
[en] In the frame of the quality assurance program for the activity quantity implemented at Laboratorio Nacional de Metrologia das Radiacoes Ionizantes/Instituto de Radioprotecao e Dosimetria (LNMRI/IRD), a 133 B solution was standardized in 1995, and submitted to the International Reference System/Bureau International des Poids et Mesures (SIR/BIPM) in order to establish ins international traceability. The SIR program, organized and supported by BIPM, allows laboratories to compare results each other and also their performances. The efficiency extrapolation technique in the 4φ(A,X)-γ coincidence counting measurements was used. The activity concentration was determined as (502115.8 ± 1481.2) Bq g-1 and (502084.0 ± 1489.0)Bq g-1 for weight and arithmetical mean, respectively. (author). 15 refs., 10 figs., 3 tabs
[en] Since 2005, the Institutul de Fizica si Inginerie Nucleara 'Horia Hulubei' (IFIN-HH) of Romania and the National Metrology Institute of Japan (NMIJ) have each submitted samples of known activity of 133Ba to the International Reference System (SIR). The values of the activity submitted were about 1.4 MBq and 6.6 MBq. The IFIN result is their first contribution to the SIR for this radionuclide and for the NMIJ this key comparison result has replaced their earlier result dating from 1986. Each of these two new results has contributed to the updating of the KCRV for this radionuclide and is included in the matrix of degrees of equivalence in the key comparison database that now contains nine results for the comparison identified as BIPM.RI(II)-K1.Ba-133. (authors)
[en] The production of 133Ba via the nuclear reaction 133Cs(p,n)133Ba on targets of CsF and CsCl has been investigated. Two methods to quantitatively separate 133Ba from the Cs target material, using AG 50W-X4 and AG MP-50 cation exchange resins, respectively, have been developed. Measured thick-target yield values are presented and some characteristics of the underlying excitation function have been inferred. For this purpose, calculations using the Geometry Dependent Hybrid model, as implemented in the code ALICE-IPPE, have been performed. Aspects of the production targetry developed as part of this study are also discussed. (author)
[en] The subject is a direct measurement of the activities of 133Ba sources by application of the theoretical count rate expressions recently developed by Novkovic et al.The total uncertainties of the activity of the measured sources, obtained in two manners, are described in this paper. The presented method is successfully tested using a germanium spectrometer with efficiencies of 50%. The accuracy of this method is proved to be comparable with the present methods of the activity measurement of 133Ba.
[en] This paper presents the absolute standardization of 133Ba by sum-peak method. 133Ba owns a complex decay and was used the sum coincidences between the average energy of characteristic X-rays (kα1 and kα2) and gamma-rays. The activity results presented uncertainty values below 0.3 % and were compared with those of other absolute activity measurement techniques. The results obtained are compared with other methods and confirm that this is an alternative, fast and efficient method for 133Ba standardization. (paper)
[en] It is well known that the Pauli principle plays a substantial role at low energies because the phonon operators are not ideal boson operators. Calculating the exact commutators between the quasiparticle and phonon operators, one can take into account the Pauli principle corrections. Besides, the ground state correlations due to the quasiparticle interaction in the ground state influence the single-particle fragmentation as well. In this paper, we generalize the basic equations of the quasiparticle-phonon nuclear model to account for both effects mentioned. As an illustration of our approach, calculations on the structure of the low-lying states in 133Ba have been performed.