Solid angle acceptance

Figure 9 shows the angular and momentum dependences of the HKS solid angle. The solid angle is near 20 msr as designed over the momentum region of 1.2 GeV/$c$ $\pm$ 12.5%. No decay factor is included in this solid angle.

Figure 10 shows the beam profiles at the collimator, Q1 entrance, Q1 exit, Q2 entrance, Q2 exit, dipole entrance and dipole exit. The solid angle is limited by Q1 height and pole shape, and Q2 width.

Figure 11 shows two dimensional presentation of the HKS angular acceptance at a given momentum. The thick curve corresponds to 7$^\circ$ scattered particle and the others correspond to 6$^\circ$ (right one), 8$^\circ$ (left one) and so on. The present configuration of the HKS covers scattering angle from 2$^\circ$ to 13$^\circ$, 170 mr horizontally and 180 mr vertically.