Chemical separation system

Skarnemark, G. Skiilberg, M. Alstadt, J. and Bjornstad, T. Nuclear Studies with the Fast In-Line Chemical Separation System SISAK, Physica Scripta, 1986, 34, 597. 

The main incentives of chip-based integrated chemical separation systems can be summarized as follows ... 

The choice of the chemical separation system has to be based on a number of prerequisites that have to be fulfilled simultaneously to reach the required sensitivity ... 

As chemical investigations progress from Z= 104-105 (with detection rates of atoms per hour), through Z= 106-108 (with detection rates of atoms per week), and on to even heavier elements (with expected detection rates of only a few atoms per month), manually performed chemical separations become impractical. With the automated liquid-phase chemical separation systems that have been developed to date, faster chemical separation and sample preparation times have been achieved. In addition, the precision and reproducibility of the chemical separations has been improved over that obtainable via manually performed separations. 

This robotic sample preparation and counting technology, together with mechanical improvements in the chemical separation system, has resulted in an automated column chromatography system that can run almost autonomously, whereas several people were required to operate the ARCA II system for a transactinide chemistry experiment. 

The drawback of this chemical-separation system thus far has been that the resulting polymer does not meet the specifications for virgin resins in some cases (see Chapter 8). The initial tests showed good separation efficiencies with PP and HDPE, but to date there remain some problems with the PVC/PS split. The property drawbacks are expected to be overcome by using other solvents before the extraction. The current cost is 13 cents per lb., including amortization of the capital start-up costs. 

Fast chemical isolation procedures to study the chemical and physical properties of short-lived radioactive nuclides have a long tradition and were applied as early as 1900 by Rutherford [1] to determine the half-life of Rn. A rapid development of fast chemical separation techniques [2-7] (see Ref. [5] for an in-depth review) occurred with the discovery of nuclear fission [8]. Indeed, the discovery of new elements up to Z = 101 was accomplished by chemical means [9]. Only from there on physical methods prevailed. Nevertheless, rapid gas-phase chemistry played an important role in the claim to discovery of Rf and Db [10]. As of today, the fastest chemical separation systems allow access to the study of a-particle emitting nuclides within less than 1 s as demonstrated by the investigation of Pa with a half-life of 0.85 s [11]. Reviews on rapid chemical methods for the identification and study of short-lived nuclides from heavy element synthesis can be found in [12-22]. 

Abstract An overview over the chemical separation and characterization experiments of the four transactinide elements so far studied in liquid phases, rutherfordium (Rf), dubnium (Db), seaborgium (Sg), and hassium (Hs), is presented. Results are discussed in view of the position of these elements in the Periodic Table and of their relation to theoretical predictions. Short introductions on experimental techniques in liquid-phase chemistry, specifically automated rapid chemical separation systems, are also given. Studies of nuclear properties of transactinide nuclei by chemical isolation will be mentioned. Some perspectives for further liquid-phase chemistry on heavier elements are briefly discussed. 

The discovery of Hs was reported in 1984 [84] with the identification of the nuclide Hs with a half-life of only 1.5 ms, far too short for all of the currently available chemical separator systems. Only in 1996, the much longer lived isotope Hs with a half-Ufe of the order of about 10 s was observed in the a-decay chain of the nuchde Cn [85]. However, the production cross-section of only about 1... 

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