## Welcome to SPECTRA home page

2021/03/01: Version 11.0.0 has been released.### What is SPECTRA?

SPECTRA is an application software to calculate optical properties of synchrotron radiation (SR) emitted from bending magnets, wigglers (conventional and elliptical) and undulators (conventional, helical, elliptical and figure-8). Calculations of radiation from an arbitrary magnetic field distribution are also available. Parameters on the electron beam and the source can be edited completely on graphical user interfaces (GUIs) and it is possible to show the calculation result graphically. The energy spectrum and radiation power after transmitting various filters and convolution of detector's resolution are also available.### Related Publications

If the users are presenting or publishing their results obtained with using SPECTRA, they are kindly requested to cite the related reference(s).- General Methods for SR Calculation: T. Tanaka and H. Kitamura, Journal of Synchrotron Radiation 8, 1221 (2001)
- Wigner Functions of SR: T. Tanaka, Physical Review Special Topics - Accelerators and Beams 17, (2014) 060702
- Coherent Mode Decomposition of Partially Coherent SR: T. Tanaka, Optics Letters 42, 1576 (2017)
- Universal representation of undulator phase errors: T. Tanaka, Physical Review Accelerators and Beams 21, 110704 (2018)

### Request for those who are reporting a bug

When reporting a bug found in SPECTRA, the users are kindly requested to attach the input file (*.json) in the e-mail, which is created before starting any calculation. The input file is placed in the directory specified in the "Output File" subpanel of the GUI, with the prefix specified in the same subpanel as well.### Important Notes on Brilliance Calculation

In version 10.0, rigorous estimation of brilliance based on the Wigner function method has become available, which is in contrast to the traditional method based on the Gaussian approximation. Although the brilliance estimation by the Gaussian approximation is still available for compatibility with the older versions, it is referred to as GA.Brilliance (Gaussian-Approximated) and is distinguished from the rigorous estimation.### Functions supported

- Energy spectra of the brilliance, flux density, partial flux after passing through a slit, and total flux
- Spatial dependence of the flux and power densities
- Beam size, angular divergence, coherent flux as a function of the gap and K value
- The peak brilliance, flux, and radiation power as a function of the gap and K value
- Radiation power after passing through a filter composed of various material
- Far-field approximation for fast evaluation of radiation
- More precise estimation of radiation in the near-field zone
- Rigorous brilliance evaluation of SR based on Wigner function representation
- Coherent mode decomposition of partially coherent SR

### Web-application mode

Since ver. 11.0, SPECTRA can be run as a "web-application", as well as the stand-alone desktop application. An example in this web server is running here. Note that, because of the limited resource of the server,__the total amount of the memory and CPU time (per process) are limited within 100 MB and 10 minutes__, beyond which the calculation is terminated. Please keep in mind that this is just an example, and please do not use it for your "bulky" calculations.