Calibration and characterization of HETG grating elements at the MIT X-Ray Grating Evaluation Facility

The high energy transmission grating spectrometer (HETGS) of the Advanced X-Ray Astrophysics Facility (AXAF) will include 336 gratings, of period 2000 angstrom and 4000 angstrom. The flight gratings have entered production, and preliminary tests for verification and calibration have begun. We present the current status of the x-ray tests at MIT, focusing on diffraction efficiency measurements and a grating tilt test. We indicate the direction the x ray testing will take in the near term.