The calibration system of the muon $g-2$ experiment.

Anastasi A., Bartolini M., Bedeschi F., Cauz D., Dabagov S., Di Sciascio G., Driutti A., Escalante O., Ferrari C., Fioretti A., Gabbanini C., Gioiosa A., Hampai D., Iacovacci M., Lusiani A., Mastroianni S., Moricciani D., Pauletta G., Piacentino G.M., Raha N., Rossi E., Venanzoni G.
  Venerdì 30/09   15:00 - 18:00   Edificio CLA - Aula T3   I - Fisica nucleare e subnucleare
The muon anomaly $(g-2)/2$ has been measured to 0.54 parts per million by the E821 experiment at Brookhaven Lab, and at present there is a 3 to 4-standard deviation difference between the SM and experimental values. A new muon $(g-2)$ experiment, E989, is being prepared at Fermilab that will improve the experimental error by a factor of four to clarify this difference. A central component to reach this fourfold improvement in accuracy is the high-precision laser calibration system which should monitor the gain fluctuations of the Calorimeter Photodetectors at 0.04% accuracy. I will review this system, focusing on the technical challenges, solutions, and achievements obtained so far.