set_pol_cplus(offset = None)
wait_temp()
wait_beam()
set_file('Ni_plus')
open_valve()
otf(start=840, end=895, time=2, delay=5)

set_pol_cminus(offset = None)
wait_beam()
set_file('Ni_minus')
otf(start=840, end=895, time=2, delay=5)

set_pol_cminus(offset = None)
wait_beam()
set_file('Ni_minus')
otf(start=840, end=895, time=2, delay=5)

set_pol_cplus(offset = None)
wait_beam()
set_file('Ni_plus')
otf(start=840, end=895, time=2, delay=5)
close_valve()