INTERCOMPARISON OF SILICON SAMPLES FROM THE AVOGADRO PROJECTS

The NIST lattice comparator assesses lattice parameter differences amo ng carefully prepared samples of monocrystalline silicon with a level of imprecision near 10(-8). This instrument has recently been used to effect intercomparisons among samples from laboratories currently enga ged in direct optical measurements of such lattice periods. We report lattice parameter differences among samples representative of current optical measurements in all active national measurement laboratories. These data are suggestive of the current state of the art of these det erminations and the population of silicon materials presently availabl e for such purposes.