<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><span style="font-size: 13px;">Theory Center Seminar</span><br><span style="font-size: 13px;">Monday, Dec. 12, 2016</span><br><span style="font-size: 13px;">1:00 p.m.</span><br><span style="font-size: 13px;">CEBAF Center, Room L102</span><br><font color="#0f61c8" size="2"><br></font><span style="font-size: 15px;"><b>Yoshitaka Taira (AIST Tsukuba)</b></span><br><b><span style="font-size: 15px;">Title: "Gamma-ray vortex generation by inverse Compton scattering"</span></b><br><font color="#0f61c8"><span style="font-size: 14px;"><br></span></font><meta http-equiv="Content-Type" content="text/html charset=us-ascii"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><span style="font-size: 14px;">Abstract: </span>In this talk, I will present a development of a gamma-ray vortex using an inverse Compton scattering (ICS). </div></div><div>The vortex beam forms a helical wavefront along the direction of propagation and carries discrete values m hbar</div><div> of orbital angular momentum (OAM) per photon. Fundamental and applied research on optical vortices using visible </div><div>wavelength lasers is ongoing. However, vortex beams are not limited to visible light but include the sub-MeV </div><div>electron vortex, ~ 10 keV X-ray vortex, terahertz wave vortex, and cold neutron vortex. ICS of a laser photon </div><div>by a relativistic electron is one of the promising technique to generate the gamma-ray vortex in the MeV and GeV</div><div>range. Gamma-ray vortex providing an additional degree of freedom will open new research opportunities to the </div><div>nuclear physics. Characteristics of the gamma-ray vortices generated via two different ICS methods and basic </div><div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>experiments of the optical vortex laser generated by a holographic grating will be presented.<span style="font-size: 14px;"> </span></div></div></div></div><br></body></html>