Invited Speakers

Alexander Rack (ESRF)

Crack propagation in a Si wafer captured with ultra-fast direct and diffraction hard X-ray imaging

Title: Depicting ultra-fast processes in real-time by direct and diffraction hard X-ray imaging
Author: Alexander Rack
Affiliation: Structure of Materials Group, European Synchrotron Radiation Facility, CS 40220, F-38043 Grenoble, France, phone 33-47688-1781, fax 33-47688-2252
Email: alexander.rack[at]esrf.fr
URL: http://www.alexanderrack.eu
The potential of hard X-ray imaging to tackle scientific questions especially related to materials sciences can be substantially increased when the dimension time is accessible. Nowadays, unprecedented temporal resolution with hard X-ray imaging can be reached at synchrotron light sources thanks to high-speed CMOS cameras combined with indirect detection schemes. Storage rings like European Synchrotron Radiation Facility (ESRF) can be operated in so-called timing-modes with reduced bunch number but increased electron bunch charge density per singlet. The polychromatic photon flux density at insertion-device beamlines during timing-modes is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding X-ray flash length is a few 100 ps FWHM). Hence, hard X-ray imaging with absorption contrast as well as phase contrast depicting processes in real time on the picosecond scale is nowadays accessible. Common bunch-rates are in the MHz regime (1.4 MHz and 5.6 MHz in case of ESRF). Additionally, direct transmission with diffraction imaging can be combined to track, for example, crack propagation in Si wafers in real-time. This gives access to information about the crack morphology and time evolution of the related strain in a simultaneous manner.
This talk will outline based concepts to reach MHz imaging rates with hard synchrotron radiation, discuss challenges and highlight recent applications. Future developments and their potential in the frame of the proposed upgrade of storage rings around the globe will be discussed.
Biographical Sketch: Alexander Rack studied Physics at the Technical University of Berlin, Germany (diploma, 2002), followed 2006 by a PhD thesis within a collaboration of the Hahn-Meitner-Institute Berlin (Department Materials Research), the BESSY II synchrotron light source (both now Helmholtz-Zentrum Berlin) and the Technical University of Berlin (Institute for Materials Processing). After several years at the ANKA light source in Karlsruhe (Karlsruhe Institute of Technology, Germany) he joined the European Synchrotron Radiation Facility in 2008, now being responsible scientist at the X-ray imaging beamline ID19 as well as deputy group head of the Structure of Materials group. He published over 100 scientific papers, one patent and contributed to several textbooks. The development and application of X-ray microimaging using (coherent) synchrotron radiation is one of his main scientific activity. Here, exploiting the pulsed structure of synchrotron light for picosecond hard X-ray imaging has been a major driver in recent years. He organized symposia and tutorials at the EuroMAT2011, EuroMAT2013 and EuroMAT2015 conference as well as the ESRF Upgrade Workshop “X-ray cinematography” and served as guest editor for the “International Journal of Materials Research (formerly Zeitschrift für Metallkunde)”