! This lattice is discussed in the Bmad manual in Lattice Examples chapter.

beginning[e_tot] = 8.955e3   ! Reference photon energy
parameter[particle] = photon

phi = 0
err = 0.01  ! Set to zero for no error
r_rowland = 0.5  ! Rowland circle radius

source: photon_init, sig_x = 5e-5, sig_y = 5e-5, spatial_distribution = uniform,
        E_center_relative_to_ref = T, sig_E = 2, energy_distribution = gaussian,
        velocity_distribution = spherical
drift1: drift
cryst: crystal, crystal_type = "Si(553)", b_param = -1, aperture = 0.050,
 curvature = {spherical = (1+err) / (2 * r_rowland)}, aperture_type = elliptical
drift2: drift
det: detector, pixel = {ix_bounds = (-97, 97), iy_bounds = (-243, 243), dr = (172e-6, 172e-6)}
daves_line: line = (source, drift1, cryst, drift2, det)
use, daves_line

!------------------

expand_lattice ! Calculates the Bragg angles needed below.

theta_in  = cryst[bragg_angle_in]  ! 78.2759 * pi / 180
theta_out = cryst[bragg_angle_out] ! 78.2759 * pi / 180

cryst[graze_angle_in]  = theta_in - phi/2
cryst[graze_angle_out] = theta_out - phi/2

drift1[L] = 2 * r_rowland * sin(theta_in-phi/2)
drift2[L] = 2 * r_rowland * sin(theta_out-phi/2)

beginning[theta_position] = theta_in + phi/2
det[x_pitch] = pi/2 - theta_out + phi/2