Recoil transfer chamber

Fig. 4. The Recoil Transfer Chamber installed at the BGS focal plane (left), and the support grid for the MYLAR foil (right).

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].

Fig. 7 Schematic of the gas-filled separator TASCA with attached recoil transfer chamber [53]...

For studies of element 108 (Hs) and Cn the new device named In-situ Volatilization and On-line detection (IVO) was developed [153]. By adding O2 to the He carrier gas, volatile tetroxides of group 8 elements were formed in-situ in the recoil chamber. A quartz column containing a quartz wool plug heated to 600 °C was mounted as close as possible to the recoil chamber. The hot quartz wool served as an aerosol filter and provided a surface to complete the oxidation reaction. For fumre smdics with Cn or FI (element 114) pure He or even a reducing He/H2 mixrnre can be employed see also Sect. 2.2.3 for experiments with in-situ volatilization techniques applied behind recoil separators and making use of recoil transfer chambers. 

Recoil Transfer Chambers (RTC) replace the so far used target chambers [149]. The lower overall efficiency, which now also includes the transmission through the separator, is compensated by the removal of the primary beam and interfering transfer reaction products. A first chemical experiment with FI at GSI using thermochromatography on Au surfaces has been conducted behind the TASCA separator in fall of 2009 [143]. 

F., Schadel, M., Schausten, B., Scheid, N., Schimpf, E., Semchenkov, A., Thorle-Pospiech, P., Toyoshima, A., Turler, A., Vicente Vilas, V., Wiehl, N., Wunderlich, T., Yakushev, A. The recoil transfer chamber—an interface to connect the physical preseparator TASCA with chemistry and counting setups. Nucl. Instrum. Methods Phys. Res., Sect A 638, 157-164 (2011)... 

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)... 

A uranium film (0.5 mg/cm2) deposited on a Ft disc (diameter 1.6 cm) Is used. The Kr activity recoiled from the target Is collected In the recoil chamber and transferred Into an evacuated cell. The Hb daughter Is then collected on a negatively charged strip of Al. 

During the detection of ionization over the range of a-rays from polonium in a hydrogen atmosphere, abnormally rapid increases were observed when no solid window was present between the Po and the ionization chamber. This was not explainable by the volatility of Po nor to the transfer of Po together with the recoil atoms of Ra G. This was explained by the assumption that a hydride, H2P0 is formed, which diffuses into the ionization chamber. Such a compound is rapidly destroyed by a small concentration of air or through the action of a-rays. The formation of such a hydride would explain the very high absorption power of Pt and Pd for Po. 

Reaction products recoiling from the target were thermalized in a rapidly flowing stream of N2 (18 L/min) and were transferred to section II, where the chlorination of the reaction products took place. The transfer efficiency was measured to be >75% and the transfer time was only about 10 s. In the reaction chamber of section II, vapors of NbCls and ZrCLj were continuously added as chlorinating agents and as carriers [135]. It was found that carriers with a vapor pressure similar to that of the investigated compound yielded optimum transfer efficiencies [114]. The addition of carriers was essential since in this manner the most reactive adsorption sites could be passivated. 

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