Berkeley gas-filled separator

This modular separation and detection system allows the use of well-understood liquid-liquid extraction separations on timescales of a few seconds, with detection efficiencies near 100%. This extremely fast chemical separation and detection system has been used with a sub-second a-active nuclide [67,68]. However, for the transactinide elements, which are produced in much lower yields with larger amounts of interfering 13-activities, detection of the a-decay of the transactinide isotopes failed. As described in Section 2.2.3, pre-separation with the Berkeley Gas-filled Separator before transport to and separation with SISAK allowed the chemical separation and detection of 4-s 257Rf [34], A schematic of the BGS-RTC-SISAK apparatus is presented in Figure 6. These proof-of-principle experiments have paved the way for detailed liquid-liquid extraction experiments on short-lived transactinide element isotopes. 

Fig. 6. Schematic of the SISAK liquid-liquid extraction system using the Berkeley Gas-filled Separator as a pre-separator.

Ninov, V., Gregorich, K.E. Berkeley Gas-filled Separator . In ENAM98, Eds. Sherrill,... 

Another perspective for SISAK is to suppress the interfering p/y background by an electromagnetic separator. J.P. Omtvedt et al. [61] performed recently first successful experiments with 261Rf by coupling SISAK to the Berkeley Gas Filled Separator (BGS) see Chapter 4 for more details. 

Fig. 3.1 Schematic of the Berkeley gas-filled separator (BGS) in combination with the Recoil transfer chamber (RTC) as used in a particular experiment [7].

Figure 16.6. (a) B. Kadkhodayan with HEVI (1992) (b) J. Kovacs and H. W. Gaggeler with OLGA (1988) (c) D. C. Hoffman and D. M. Lee with MG rotating wheel system (d) J. V. Kratz and M. Schadel with Automated Rapid Chemistry Apparatus (1988) (e) Schematic diagram of a typical SISAK liquid-liquid extraction configuration with Berkeley Gas-filled Separator as a preseparator. 

The Berkeley Gas-Filled Separator (BGS) was used as a preseparator for Rf produced in the Pb( Ti, In) reaction followed by the transfer of Rf to a gas jet delivering the activity to the SISAK system (Omtvedt et al. 2002). This reduced the interfering p and y radiation by more than three orders of magnitude thus enabling the unambiguous detection of Rf by ESC. 

Kirbach, U.W., Gregorich, K., Ninov, V., Lee, D.M., Patin, J.B., Shaughnessy, D.A., Strellis, D.A., Wilk, P.A., Hoffman, D.C., Nitsche, H. The recoil product transfer chamber (RTC) A new interface for heavy element chemistry studies at the Berkeley gas-filled separator. In Nuclear Science Division Annual Report 1999. Lawrence Berkeley National Laboratory, Berkeley, (1999)... 

The experiments at Dubna (Russia) and RIKEN (Japan), and LBNL Berkeley (USA) have been carried out with gas-filled separators. Gas-filled separators (Mtinzenberg 1997 Oganessian 2007) are filled with helium (GSI, RIKEN, LBNL) or hydrogen (Dubna) and maintained at a pressure of typically 0.5 mbar. A schematic view is given in O Fig. 19.8. Heavy nuclei recoil from the rotating target into the dipole magnet where they are separated... 

SHE chemistry at the picobarn level gives access to the elements 114 and heavier and is another important issue for future research. This would include addressing the important question of where the Mendeleev systematic will break down due to relativistic effects of the inner electrons of increasingly heavy, proton-rich nuclei. Pre-separation with gas-filled separators such as BGS at LBNL Berkeley, GARIS at RIKEN, or TASCA at GSI have been successfully applied in SHE chemistry experiments (Diillmaim 2008). 

Several years before Armbruster s discovery, in 1991, Albert Ghiorso and others of the Berkeley group produced atoms of element 110. They did this by identifying the atoms of Uun by the products of the decay chain, using their new gas-filled Small Angle Separator System (SASSY-2). The reaction follows ... 

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