Towards brilliant neutron micro-beams

The wavelength of any FEL is limited to the minimum value at which the quantum-fluctuation-induced energy spread prevents the FEL process. In contrast to the large-scale X-FEL facilities planned world-wide, our laser-plasma-accelerator-based FEL offers the advantage of greater tolerance with respect to energy spread, thus considerably lowering the wavelength limit. Of course, such a γ-FEL will not be of table-top size any more, but would still not exceed currently pursued large-scale X-FELs. A γ-FEL will open the path to a new class of fundamental investigations like nuclear resonant lasing in gamma optics. The main aspect of this subproject is to contribute theoretical considerations from nuclear physics in order to plan details of a future γ-FEL with respect to converting brilliant monochromatic γ-photons in the 5 – 6 MeV range into brilliant, slow neutron beams with small source diameter using (γ,n)-reactions. The peak and average brilliance of this source may potentially exceed by about 10⁸ and 10⁶ times those of present-day thermal neutron sources from nuclear reactors, respectively. Since the neutral neutron beam offers properties very different to those of a neutral X-ray beam, such as magnetic moment, isotope-specific scattering length, etc., it will allow us to obtain complementary information. As the γ-FEL will not become reality during the first 10-year period of MAP, this project constitutes a feasibility study.