parameter[p0c] = 4e9
parameter[geometry] = closed
bmad_com[spin_tracking_on] = T

q1: quad, l = 0.5, k1 = 0.6, vkick = 0.001 
q2: quad, l = 0.5, k1 = -0.5

d: drift, l = 0.3
b: sbend, l = 3, angle = pi/8, e1 = 0.07, e2 = 0.07

rf: rfcavity, l = 1.2, rf_frequency = 250e6, voltage = 5e6
m: marker

sector: line = (d, q1, d, b, d, q2, d, rf, b)
ring: line = (m, 8*sector)

use, ring