Inverse Compton scattering of coherent synchrotron radiation in an energy recovery linac

Abstract

We propose inverse Compton scattering (ICS) of coherent synchrotron radiation (CSR) from a relativistic short electron bunch in energy recovery linacs (ERL) as a high-flux subpicosecond x-ray and $\ensuremath{\gamma}$-ray source. An advantage of the CSR scheme over a conventional ICS source is that no external laser is required, and synchronization between CSR pulses and electron bunches is obtained automatically. Moreover, higher-flux x rays can be generated from the ICS of CSR in an ERL operated at a high repetition rate, 100 MHz to 1.3 GHz. Using parameters of the Compact ERL at KEK, $1\ifmmode\times\else\texttimes\fi{}{10}^{13--14}\text{ }\text{ }\mathrm{phs}/\mathrm{s}$ b.w. 10% (the number of photons ${\mathrm{pulse}}^{\ensuremath{-}1}$ bandwidth ${\mathrm{unit}}^{\ensuremath{-}1}$) x ray with a 100 fs--1 ps pulse duration can be obtained, for an energy range from 0.04 to 4 keV. In the case of a 5-GeV ERL, $\ensuremath{\gamma}$ rays with energy around tens of MeV are generated with $1\ifmmode\times\else\texttimes\fi{}{10}^{8}\text{ }\text{ }\mathrm{phs}/\mathrm{pulse}$ b.w. 10% at a repetition rate of several hundreds of MHz.