Recoil Mass Spectrometer Target Chamber

Recoil Mass Spectrometer Target Chamber
The RMS beam height is approximately 2 meters high. The target chamber is 15 cm in radius and made out of thin-walled aluminum to minimize absorption of gammas. It has a forward fantail at 30o which extends some 30 cm from the target. It is supported from above and there is a flange which opens to the inside of the support structure as can be seen in Fig. 1. There are two flanges at the bottom which permit the insertion/extraction of the target and charge reset foil without letting the chamber up to air. This feature is very beneficial in the RIB environment. Two small viewports allow a phosphor (red alumina) on a rotatable feedthrough to be placed in front of HyBall and be seen by a camera. The target is some 72 cm from the first quadrupole of the RMS. The back flange can be replaced to hold the forward array or an 8-inch cross (see Fig. 2).

Fig. 1 - A photograph of the RMS target chamber and a drawing (pdf) can also be downloaded.
The large distance between the target and the first quadrupole of the RMS gives us great flexibility. A 19-element neutron detector array can be placed here, the forward array, or an 8-inch ID cross as is shown in Fig. 2. The cross has held an MCP (fusion-evaporation detector based on timing) or several silicon detectors (forward angle scattering). The center of the cross is approximately 55 cm from the target. This cross is not compatible with the neutron detectors. The scattering and stripping by the foil of an MCP makes it incompatible with detection by the RMS.

Fig. 2 - A photograph of the downstream section of the RMS target chamber where an 8-inch ID cross has been placed between the target chamber and the first quadrupole of the RMS.
The upstream area of the target is shown in Fig. 3. The 8-inch ID cross upstream can hold an MCP although scattering of RIBs near the target area may be problematic for the Ge detectors. A kapton window has been mounted on the right side of the cross. Between the cross and the target is a four-jaw slit system for centering the beam.

Fig. 3 - A photograph of the upstream section of the RMS target chamber.

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This file last modified Monday January 08, 2007