BREMS: Partial-wave calculation of spectra and angular distributions of electron-atom bremsstrahlung at electron energies less than 30 MeV (New Version Announcement)

• Published in: Computer physics communications 2022-09, Vol.278, p.108414, Article 108414
• Main Author: Poškus, Andrius
• Format: Article
• Language: English
• Subjects: Bremsstrahlung angular distribution; Bremsstrahlung spectrum; Dirac partial-wave calculations; Electron-atom bremsstrahlung
• ISSN: 0010-4655; 1879-2944
• DOI: 10.1016/j.cpc.2022.108414

A new version of the Fortran program BREMS, which calculates single- and double-differential cross sections (DDCS) of electron-atom bremsstrahlung by the relativistic partial-wave method, is presented. The detailed description of the program is given in the original paper [Comput. Phys. Commun. 232 (2018) 237–255]. The new numerical methods implemented in the latest version include cubic spline interpolation of the radial matrix elements with respect to the orbital quantum number of the emitted photon, and usage of scaling properties of the partial-wave DDCS as a function of two variables – the photon emission angle and the number of partial waves retained in the truncated partial-wave series. As a result of improvements of efficiency and accuracy of the code, the endpoint of the energy range where the partial-wave calculations of bremsstrahlung cross sections are feasible has been increased by an order of magnitude (from 3 MeV to 30 MeV). In addition, three “special” modes of operation, which do not involve partial-wave calculations, but can be used to provide some auxiliary quantities, have been implemented. Program Title: BREMS CPC Library link to program files:https://doi.org/10.17632/mvd57skzd9.2 Developer's repository link:https://web.vu.lt/ff/a.poskus/files/2017/09/Brems.zip Licensing provisions: CC BY NC 3.0 Programming language: Fortran 90 Journal reference of previous version: Comput. Phys. Commun. 232 (2018) 237–255 Does the new version supersede the previous version?: Yes Reasons for the new version: The new version offers better accuracy and better performance at high electron energies, so that partial-wave calculations of single- and double-differential cross sections (SDCS and DDCS, respectively) at outgoing electron energies greater than 20 MeV become feasible. In addition, it includes three “special” modes of operation, which do not require the partial-wave method: (a) calculation of the approximate analytical DDCS and SDCS using the screened Born approximation or the Sommerfeld-Maue approximation with the screening correction, (b) fitting of an arbitrary tabulated screening function by a linear combination of decaying exponentials, (c) spline fitting and interpolation of the SDCS with respect to the kinetic energy of the incident electron. Summary of revisions: The coupled radial Dirac equations for the continuum wave function are now solved by the power-series method [1]. The maximum number of incident or outgoing partial waves (|κ1|max