From narrow to wide band normalization for orbit and trajectory measurements

The beam orbit measurement (BOM) of the LEP collider makes use of a narrow- band normalizer (NBN), based on a phase processing system. This design has been working fully satisfactorily in LEP for almost 10 years. Development work for the LHC, requiring beam acquisitions every 25 ns, has led to a new idea of a so-called "wide-band normaliser" (WBN), which exploits most of the pickups differentiated pulse spectrum. In the WBN, the beam position information is converted into a time difference between the zero-crossing of two recombined and shaped electrode signals. A prototype based on the existing NBN unit has been developed and tested to prove the feasibility of this new idea. For this the bandpass filters and the 90° hybrids are replaced by lowpass filters and delay lines.