Target Chamber - Spectrometer Coupling

The aluminum middle ring will support a flange on each side for each high resolution spectrometer. Four flanges will be available: Two flanges will contain a 6 $in$ window opening which will be covered with a thin foil (e.g., 10 mil aluminum) . These two flanges will be used for experiments utilizing extended targets that do not require optimum momentum resolution. The other two flanges will have two fixed ports (with a 8 $in$ $\times$ 6 $in$ opening) which will be mainly used for calibration of the spectrometers . Fixed ports are centered at 16.11 $^\circ$ and 45 $^\circ$ for one flange and at 16.11 $^\circ$ and 90 $^\circ$ for the second flange.

For a point beam on target a vertical opening in the walls of the chamber of height 57.15 cm x 0.065 x 2 = 7.43 cm is required so that the scattered beam is within full acceptance of the spectrometer. If the beam is rastered on target $\pm$0.5 cm in the vertical direction, then the opening in the outer side of the chamber must be at least 8.5 cm for full acceptance.

From consideration of the angular range of the spectrometers in the standard tune, the scattered beam acceptance envelope, the effects of an extended gas target on acceptance, and the effects of a rastered beam $\pm$ 5 mm on acceptance, the target chamber requires a window of at least 8.5 cm high in the aluminum ring extending from 6.33 $^\circ$ (2.48 in) from the beam exit point to 8.83 $^\circ$ (3.47 in) from the beam entrance point on one side and a similar window on the other side of the beam. For future considerations (e.g., using a third arm or sliding seal) the width of the window on the middle ring was actually constructed to be 17.78 cm (7 $in$).