We are investigating a standing wave accelerator structure that uses a rf feed to each individual cell. This approach minimizes rf power flow and electromagnetic energy absorbed by an rf breakdown. The objective of this work is a robust high-gradient (above 100 MV/m) X-band accelerator structure.

We use angle-resolved photoemission spectroscopy to study twinned and detwinned iron pnictide compound NaFeAs. Distinct signatures of electronic reconstruction are observed to occur at the structural (T{sub S}) and magnetic (T{sub SDW}) transitions. At T{sub S}, C{sub 4} rotational symmetry is broken in the form of an anisotropic shift of the orthogonal d{sub xz} and d{sub yz} bands. The magnitude of this orbital anisotropy rapidly develops to near completion upon approaching T{sub SDW}, at which temperature band folding occurs via the antiferromagnetic ordering wave vector. Interestingly, the anisotropic band shift onsetting at T{sub S} develops in such a way to enhance the nesting conditions in the C{sub 2} symmetric state, hence is intimately correlated with the long range collinear AFM order. Furthermore, the similar behaviors of the electronic reconstruction in NaFeAs and Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} suggests that this rapid development of large orbital anisotropy between T{sub S} and T{sub SDW} is likely a general feature of the electronic nematic phase in the iron pnictides, and the associated orbital fluctuations may play an important role in determining the ground state properties.

Online article printed from Abilene Reporter-News about a plane from the WASP training years, a 1944 Fairchild PT-19A, that still runs and is taken care of by Bill Johnson.