Bunch tracking in TAO give strange results when changing tracking method

[henrylovelace3]

Bmad_tracking and Runge_Kutta give very different z-pz profiles.
Attached is a zip file containing the lattice file, tao.init, and error script.
error.zip

Bmad_standard

Runge-Kutta

[DavidSagan]

@henrylovelace3 First I am getting an error:

lnx4200:~/linux_lib/test_love> taonl cct-iso.bmad 
[WARNING] set_ptc:
    Note: Radiation calculation in PTC not correct for particles of type: #234Ra+53
[INFO] tao_init:
    Negative damping partition number detected therefore the lattice is unstable with radiation excitations.
    Note1: This may not be a problem if the amount of radiation generated is low (like for protons).
    Note2: Instability with respect to radiation excitations does not affect such things as the closed orbit calculation.
[ERROR | 2024-DEC-09 15:19:14] read_beam_file:
    CANNOT OPEN BEAM FILE: "iso_1.dat"
[ABORT | 2024-DEC-09 15:19:14] init_beam_distribution:
    PROBLEM READING BEAM POSITION FILE: "iso_1.dat"
[ERROR | 2024-DEC-09 15:19:14] tao_inject_beam:
    BEAM_INIT INITIAL BEAM PROPERTIES NOT PROPERLY SET FOR UNIVERSE: 1

Another thing is that the bmad_standard tracking can be affected by the number of steps through a given element. Try increasing the number of steps and see what happens.

Additionally, please try to simplify things. One one particle is needed and please cut down on the number of elements to be tracked through. You should be able to reduce the test to a single element. And with single element tracking, the tracking_method_test program is the best way to see what the differences are between different tracking method.

[henrylovelace3]

Updated zip file and reduced the number of bunches. The step size test showed no change in the distribution.

error.zip

[DavidSagan]

@henrylovelace3 Try reducing the problem to a single particle and one element. What do you see?