13.17 Highlights of What’s New in Version 2019.2.1

Here is a summary of what’s changed since release 2019.1.1.

13.17.1 Bug Fixes for Elements

• Fixed a bug in tracking-based matrix computation for CCBEND that would result in the program hanging under some circumstances.
• Fixed a bug in the implementation of the expanded Hamiltonian for MULT elements.
• Fixed a bug in the BMXYZ element that caused a crash when multiple such elements were used.
• If COUPLING and EYREF were both non-zero for an SREFFECTS element, the EYREF value would be ignored, which is potentially confusing. This issue is now flagged as an error. B. Podobodov (BNL) brought the issue to our attention.

13.17.2 Bug Fixes for Commands

• The correct command, which performs trajectory or orbit correction, would fail to output corrector data for both planes in some cases. This was fixed.
• The correct command, also had a bug in reporting the “uncorrected” trajectory in the trajectory output file. Instead of giving the uncorrected trajectory, it was giving the trajectory after the penultimate correction iteration. This was reported by forum user shancai.
• The memory-efficiency of bucket assignments, invoked when using use_bunched_mode in sdds_beam, was improved, preventing crashes in some extreme cases for the serial version.

13.17.3 New and Modified Elements

• Added the APCONTOUR element, which provides an aperture or obstruction defined by an (x,y) contour in an SDDS file.
• Added the TAPERAPC element, which provides a tapered circular aperture.
• Added the TAPERAPE element, which provides a tapered elliptical aperture.
• Added the TAPERAPR element, which provides a tapered rectangular aperture.
• RFMODE now allows ignoring particles that are outside the binning region, using the ALLOW_UNBINNED_PARTICLES parameter.
• The required format for MATR (matrix from a text file) has changed slightly, as described on the manual page. The element also has a new parameter, FRACTION that allows interpolating the matrix elements with the identity matrix as one endpoint.

13.17.4 New and Modified Commands

• The ion_effects command now supports calculation of ion fields using a bi-gaussian distribution (sum of two gaussians) or bi-lorentzian distribution (sum of two lorentzians), as well as tri-gaussian and tri-lorentzian distributions. This which allows modeling the core and tails of the distribution more accurately. A number of parameters were added for control of fitting and output. J. Calvey (ANL) and R. Lindberg (ANL) co-developed this improvement.
• The sdds_beam command now offers control of which bunch is used for fiducialization of rf systems. It defaults to the first bunch (#0), which is a change from the previous (and frequently confusing) behavior of fiducializing to the entire beam.
• The aperture_search command now allows full-plane computations, i.e., computations covering both y ≥ 0 and y < 0.

13.17.5 Changes Specific to the MPI Parallel Version

• None

13.17.6 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.

13.17.7 Changes to Related Programs and Files

• The touschekLifetime program now reports the value of deltaLimit in the output file, whether that value is given explicitly or computed via the rf voltage.
• Added the program sdds5x5sigmaproc, which computes the 5x5 sigma matrix (i.e., all elements except those related to the time coordinates) from a quadrupole scan.