Update on Large Grain Cavities with 45 MV/m in a Nine-Cell Cavity at DESY.

Abstract

Since 2009 a series of eight nine-cell cavities (AC151 – AC158) of TESLA shape fabricated of large grain (LG) niobium material is under preparation and test at DESY. In a first step all cavities were tested after a BCP treatment. In a second step additional electro polishing is applied to all cavities. In this paper the treatment will be discussed and a first excellent result of AC155 will be reported