The spectrometric system for ionizing radiation measurement with pile-up rejection and counting losses correction has been described. The results for HpGe, Ge(Li), Si(Li) and surface barrier detectors have been presented. The total count rate ranged from 500 to 105 cps and different radioisotopes have been used. The counting losses correction accuracy has been within ±1% with tenfold reduction of background from pile-up pulses. The possibility of the system application for radiation intensity measurement of the mixture of short- and longlived radioisotopes has been discussed.
Authors:E. Hoppe, C. Aalseth, R. Brodzinski, A. Day, O. Farmer, T. Hossbach, J. McIntyre, H. Miley, E. Mintzer, A. Seifert, J. Smart, and G. Warren
The search for neutrinoless double beta decay in 76Ge has driven the need for ultra-low background Ge detectors shielded by electroformed copper of ultra-high radiopurity (<0.1
μBq/kg). Although electrodeposition processes are almost sophisticated enough to produce copper of this purity, to date there
are no methods sensitive enough to assay it. Inductively coupled plasma mass spectrometry (ICP/MS) can detect thorium and
uranium at femtogram levels, however, this assay is hindered by high copper concentrations in the sample. Electrodeposition
of copper samples removes copper from the solution while selectively concentrating thorium and uranium contaminants to be
assayed by ICP/MS. Spiking 232Th and 238U into the plating bath simulates low purity copper and allows for the calculation of the electrochemical rejection rate of
thorium and uranium in the electroplating system. This rejection value will help to model plating bath chemistry.
Authors:Jesus Molina, Gyula Vatai, Eszter Fogarassy, and Erika Bekassy-Molnar
Andry E. Y. (2002) Rejection of single salts versus transmembrane volume flow inRO/NF: thermodynamic properties, model of constant coefficients, and itsmodification,
Journal of Membrane Science
, 198, 285
Due to the fact that pulse rise time is coincident with the fall time of the previous pulse in the Preloaded Filter pulse processor, it has a definite throughput advantage over all other pulse shaping methods. So, for the first time, it was possible to achieve throughput rates of60Co after pileup rejection in excess of 100 kc/s, at substantially better resolutions than those of other high rate shaping amplifiers.
The liquid-liquid extraction method used with alpha liquid scintillation with rejection of -emission is strongly dependent of the nature of the aqueous solution containing actinides. We propose to measure plutonium quantitatively by its labelling with236Pu. Two procedures of quantitative extraction have been developed as well as the mathematical fit to obtain accurate results. The limits of detection have been determined for several counting times like for instance 0.2 pg/l after one day of acquisition time. We have applied both procedures successfully for the determination of plutonium in doped drinking water and in solid samples after dissolution.
Authors:Péter Bor, József Csanádi, Gábor Veréb, Sándor Beszédes, Zita Šereš, Zsuzsanna László, Cecilia Hodúr, and Szabolcs Kertész
To meet the requirements defined by environmental protection regulations effective wastewater treatment is required to process effluents before discharging them into sewers or living waters. While membrane separation offers a quite advantageous method to reduce the organic load of wastewaters, membrane fouling is still limiting its application in wastewater treatment.
In this study, the possibility of membrane fouling reduction by increased shear rates on the surface of the membrane was investigated. 7 and 10 kDa MWCO ultrafiltration and 240 Da nanofiltration membranes were studied, with the use of a laboratory mode Vibratory Shear Enhanced Processing. This work mostly focused on studying the effects of module vibration and recirculation feed flow rate on permeate flux, specific energy demand and membrane rejections. Using the same operation parameters, vibration and non-vibration mode experiments were carried out with high and low recirculation flow rate to have a deeper understanding of the shear rate effects. It can be concluded that higher shear rate had a positive effect on the process: increased shear rate resulted in higher flux, higher overall rejection values, as well as a significantly decreased specific energy demand. By calculating and comparing the shear rates in experiments with different operating parameters, both vibration and nonvibration mode, both low and high recirculation flow rate, we have reached the conclusion that vibration causes a significantly higher shear rate increase than setting the recirculation flow rate high.
Authors:B. Wierczinski, J. Alstad, K. Eberhardt, J. Kratz, R. Malmbeck, M. Mendel, A. Nähler, J. Omtvedt, G. Skarnemark, N. Trautmann, and N. Wiehl
Fast solvent extraction is a chemical separation method, which can be applied to study exotic nuclides. Since about 1970 the
SISAK technique, which is an on-line method based on multi-stage solvent extraction separations, has been successfully used
to investigate the nuclear properties of β-decaying nuclides with half-lives down to about one second. During the last decade
it has become possible to produce transactinide elements in high enough yields to investigate their chemical properties on
a one-atom-at-a-time scale. For this purpose it was necessary to improve and change the detection part of the SISAK system
in order to be capable to detect spontaneously fissioning and α-decaying nuclides in a flowing organic solution. This technique
is based on liquid scintillation counting with pulse-shape discrimination and pile-up rejection
Authors:Scott Tumey, Thomas Brown, Terry Hamilton, and Darren Hillegonds
Based on the encouraging results of our initial efforts to develop a 90Sr accelerator mass spectrometry capability, we have undertaken efforts to enhance our system. By changing some key operating
parameters and constructing an optimized detector we were able to improve the discrimination of 90Sr from the isobaric interference 90Zr and reduce our instrumental background by nearly two orders of magnitude. Our current background (4 × 106 atoms, 3 mBq) is comparable to that achievable by decay counting, but is still a factor of ten higher than what is theoretically
predicted based on the efficiency of our system. Therefore, future plans include implementation of a time-of-flight system
to improve the rejection of 90Zr.
Authors:Dazhu Yang, Yongjun Zhu, and Rongzhou Jiao
A new method for the determination of transuranium elements, Np, Pu and Am with extraction-liquid scintillation counting has been studied systematically. Procedures for the separation of Pu and Am by HDEHP-TRPO extraction and for the separation of Np by TTA-TiOA extraction have been developed, by which the recovery of Np, Pu and Am is 97%, 99% and 99%, respectively, and the decontamination factors for the major fission products (90Sr,137Cs etc.) are 104–106. Pulse shape discrimination (PSD) technique has been introduced to liquid scintillation counting, by which the counting efficiency of -activity is >99% and the rejection of -counts is >99.95%. This new method, combining extraction and pulse shape discrimination with liquid scintillation technique, has been successfully applied to the assay of Np, Pu and Am in high level radioactive waste.
extremely short and the reports submitted by him are substantial and help perfectly the decision of the Editors. The rejection rate based on his reviews is ∼40 %, which value fits to the general rejection rate of the Journal of Thermal Analysis and