Elegant users forum

Hi all
I am trying something really simple ... on paper.
Calculating the injection efficiency (IE) by counting the number of particles tracked after a certain number of turns
This is part of a MOGA optimization where errors are introduced/propagated through different calculations

The fragment where I perform the IE calculation is reported below

At the watch-point W3 an INTERVAL of 100 counts is defined, then a run_control with n_passes = 101, so after 100 turns a result
is saved. Ideally a *.w3 file should be created with 2 pages, page=1 with a parameter Particles=1000
and page=2 with Particles<=1000 (some electrons being lost in the ring).

The critical element, in this case, seems to be the introduction of the file <rootname>.param (red block), which contains
a definition of INTERVAL=1 for watchpoint W3. However my idea was to override this definition by using alter_elements (green lines)

Elegant though does not seem to care about this

So the question is: why alter_element seems not to do its job?

Thanks very much for any clue ... Marco

! -------------------------------------------------
! Injection Efficiency with OFF-axis beam at -5.0mm
! -------------------------------------------------

&run_setup
lattice = <rootname>.new
use_beamline = RINGRF,
p_central_mev = 3.5e3,
default_order = 3,
rootname = <rootname>
semaphore_file = %s.done0
magnets = %s.mag
losses = %s.lost
&end

&load_parameters
filename = <rootname>.param
allow_missing_elements = 1
&end



&alter_elements
name=W3,
item=INTERVAL,
value = 100
differential=0,
multiplicative=0
&end


&alter_elements
name=RFC,
item=CHANGE_T,
value="0",
differential=0,
multiplicative=0
&end

&run_control
n_steps = 1,
n_indices = 0,
n_passes = 101
reset_rf_for_each_step = 1
first_is_fiducial = 0
restrict_fiducialization = 0
&end

&twiss_output
filename = %s.twi
concat_order = 2
radiation_integrals = 1
compute_driving_terms = 1
&end

&sdds_beam
input = input_coords.sdds,
input_type = "elegant",
sample_interval = 1,
reuse_bunch = 0,
&end

&track
center_on_orbit=0,
center_momentum_also=0,
offset_by_orbit=1,
offset_momentum_also=1
&end

! -----------------
! Momentum Aperture
! -----------------

etc, etc ...

Marco,

Try setting alter_at_each_step=1 on the &alter_elements commands. Otherwise, the command takes place immediately and then gets squashed by &load_parameters.

Alternatively, you can use put exclude_type_pattern="WATCH" in the load_parameters command, so it will ignore data for WATCH elements.

--Michael

Hi Michael,

Using this example I tried the following but unable to get output for each interval. It printout each turns instead of specific turns.

&run_setup
lattice = SR_1000MeV.lte,
use_beamline = SR_cooler,
p_central = 293.54100292171,
parameters = "%s.param",
! rootname = <rootname>
default_order = 2,
always_change_p0 = 0,
&end

&load_parameters
filename = "%s.param"
allow_missing_elements = 1,
exclude_type_pattern="WATCH"
&end

&alter_elements
name=w1,
item=INTERVAL,
value = 100,
allow_missing_elements=1,
alter_at_each_step=1
&end
and I have defined w1 as:
w1: watch,filename="%s.w1",mode="coordinates"

I am trying this in elegant. Finally I have to apply it for pelegant. I need to run for million turns and need to save specific turns due to some memory issues.

Any help will be appreciated.

Sincerely,
Bhawin

Bhawin,

What you are doing should work. I do basically the same thing all the time. Try using &save_lattice at the end of the run to save your lattice and verify that it is as you expect.

--Michael

Hi Michael,

Now, it works. Thank you so much.

Sincerely,
Bhawin