The calibration system for the muon g-2 experiment at Fermilab.

Atanu Nath
  Mercoledì 13/09   09:00 - 13:00   Aula A208   I - Fisica nucleare e subnucleare
The muon g-2 experiment at Fermilab (E989) plans to measure the muon anomaly with a total uncertainty of $1.6\times 10^{-10}$ (0.14 ppm), including a 0.10 ppm statistical error and a 0.07 ppm systematic uncertainty both on the muon anomalous precession angular velocity $\omegaa$ and on the magnetic field measurement with the proton Larmor precession angular velocity $\omega p$. To achieve this statistical uncertainty, the experiment must detect more than $1.8\times 10^{11}$ positrons with energy greater than 1.8 GeV, measured by 24 calorimeters, each consisting of 54 crystals, distributed around the ring. The response of each of the 1296 channels must be calibrated and monitored to keep uncertainties due to gain fluctuations at the sub-permil level in the time interval corresponding to one beam fill (700 $\mu$s) and at the sub-percent level on longer timescales. We will describe in the poster the laser-based calibration system that distributes light to all channels being meanwhile monitored with the necessary accuracy. The performances of the calibration system have been demonstrated in two test beams (at BTF and SLAC) before being installed in Fermilab where in next fall data taking will start.