Element Aperture

To see how that works, we put an aperture in the example program 10, we see at 10 the calls

call put_an_aperture(.002d0,0.001d0)
call remove_temporarily_an_aperture
call Track_and_test_aperture

And we call the subroutine Track_and_test_aperture 10.5. This subroutine has the following input:

call put_back_an_aperture

write(6,*) "aperture => True or false "
read(5,*) aperture_flag
write(6,*) " Check_madx_aperture (magnet aperture) => True or false "
read(5,*) check_madx_aperture
write(6,*) " Give value of the absolute_aperture "
read(5,*) absolute_aperture

WRITE(6,*) " GIVE A 'BIG' INITIAL VALUE (ONE NUMBER) FOR X(1:6)= R (example 0.1) " 
READ(5,*) R

The reader can check his understanding of the code by inputing values of the absolute_aperture and R either much bigger or much smaller than the arguments of put_an_aperture,--0.002 and 0.001 at the moment.

Some important points:

• The Absolute_aperture should be big, say 1 metre or more, however it should not be too big in order to prevent the apparition of a NAN-- ideally, somewhere clearly outside the beam pipe but not on the Andromeda Galaxy.
• the flag check_madx_aperture controls the user defined apertures globally.
• Locally one can turn off an aperture by chaning its ``kind'' to a negative number. See the example program at 10.5.