13.4 Highlights of What’s New in Version 2022.2

Here is a summary of what’s changed since release 2022.0.

13.4.1 Bug Fixes for Elements

• The open-side feature of the MAXAMP element behaved incorrectly when the dimension in one plane was not set, as reported by Z. Duan (IHEP).
• When using moments_output computations for a beamline that contained SBEN elements, a less accurate model was used compared to the same computation with CSBEND elements. V. Sajaev (ANL) helped find this bug.
• The pole-factor parameters of CWIGGLER gave strange results when the number of integration steps per half period was odd. This was reported by forum user Skamarokha. It was fixed by forcing STEPS_PER_PERIOD to be 4n, where n is an integer.
• The START_PID and END_PID parameters of WATCH did not permit selecting a single particle. This issue was identified with the help of C. Li (DESY).

13.4.2 Bug Fixes for Commands

• The correct command had a bug related to threaded and one-to-one trajectory correction if removal of pegged correctors was not invoked.

13.4.3 New and Modified Elements

• The CWIGGLER element can now be split using the divide_elements command or the element_divisions parameter of the run_setup command. In addition, multiple CWIGGLER elements that are separated only by MARK or WATCH elements are considered part of the same element. This was suggested by forum user Skamarokha.
• The LGBEND element now allows the user to provide z-dependent aperture data via an SDDS file.
• The SPEEDBUMP element now provides information for logging of global coordinates of lost particles.
• The HMON, VMON, and MONI elements now provide the number of particles seen on the most recent turn for use in optimization. These are, in essence, virtual BPM sum signals.
• The BMXYZ element now allows specifying the range over which the optional constant field is applied.
• Added ability for BMXYZ and BRAT elemente to use sections of field maps with defined symmetry, which reduces storage requirements.
• The BMXYZ element now applies apertures defined by MAXAMP, APCONTOUR (with STICKY=1), and aperture_data in the interior.
• The APCONTOUR element now accepts multiple contours combined via user-defined logic.
• The WAKE, TRWAKE, ZLONGIT, and ZTRANSVERSE elements now allow limiting which bunches are subjected to short-range impedance effects, using the START_BUNCH and END_BUNCH parameters. This was suggested by forum user Seb_Wilkes and can provide significant reduction in run time for some types of simulations.
• The RFDF element now allows restricting effects based on particle ID values. This was also suggested by forum user Seb_Wilkes.
• The KAverage and pAverage values were wrong in output files for WATCH elements for the parallel version. This was pointed out by C. Li (DESY).

13.4.4 New and Modified Commands

• The correct command (orbit and trajectory correction) now supports Tikhonov regularization of the singular value spectrum in creating the inverse matrices, following some ideas of V. Sajaev (ANL).
• The optimization_term command now recognizes two new quantities: sMaxTransmitted and sMaxTransmittedMonitor, giving the maximum s coordinate to which particles are transmitted to any point or to a monitor, respectively. This can be used for threading of beam through a transport line.
• Added 1d-scan and RCDS [62] methods to the optimize command.
• Added the slope_limit and coord_limit parameters to the global_settings command. These allow controlling the limiting values for particle motion, beyond which particles are considered lost.

13.4.5 Other Changes

• None

13.4.6 Changes Specific to the MPI Parallel Version

• None

13.4.7 Changes Specific to the GPU Version

The GPU version continues to be an alpha release and contains bugs. Users are encouraged to check results against the serial or parallel versions and report issues to the developers.

• None.

13.4.8 Changes to Related Programs and Files

The elegant distribution includes many programs and scripts that perform computations with elegant output data, provide interfaces with other programs, or prepare data for use with elegant. These are listed in Section 8.

Changes to these tools in this release include

• The straightDipoleFringeCalc program now allows the user to specify the arc length of the CCBEND element, rather than relying on the internal calculation, which may not be accurate.