MD1446 –β∗–Reach: Impedance Contribution of Primary Collimators

This report summarizes the results of MD1446 on impedance measurements of single primary collimators. The measurements were carried out during MD block 3 of 2016, on the night between 10th and 11th September. The impedance of each collimator was measured from the tune–shift induced by varying the collimator gap. In order to have a clearer signal, the tune was reconstructed from damped oscillations of the beam, coherently kicked with the tune kicker, as done in previous MD activities. The results are in close agreement with expectations. Another method of kicking the beam was tested at the end of the MD, i.e. via the ADT; this alternative method proved to offer flexibility and precision higher than the former, paving the way to future measurements of the same kind. The merit of this MD activity is related to the possibility of tightening the collimator settings, to accommodate smaller values ofβ∗in the LHC.