The geometry of Phobos is such. The y-axis points up away from the center of the Earth. The x-axis is pointing out from the center of the RHIC ring. This requires the z-axis to point in the clock-wise direction of the beam.

The rough design geometry of the TOF wall with only two wall segments covers only 1.42% of the solid angle. The wall was designed to have a 15% occupancy, which is way the scintillator slats cover a 20cm x 8mm area with respect to the interaction point with a 1mm gap between each scintillator. Therefore, the total length of a wall segment is 1080mm. The inner segment covers angles in theta, the angle with respect to the beam pipe, of 90^o to 55^o and has a distance of 1.7m at 90^o from the interaction point. The outer segment covers angles of 55^o to 32.5^o with a distance from the interaction point of 2.6m at 55^o. At these distances, the angle in phi, the angle with respect to the x-axis, for the inner wall is 7^o and for the outer is 4^o. Both of the two wall segments cover a pseudo-rapidity range of 0 to 1.25.

(All units below are in centimeters and degrees.)