The readout system for the Fermilab Muon $g-2$ straw tracking detectors

Abstract

The Fermilab Muon g − 2 experiment aims to measure the anomalous magnetic moment of the muon to a precision of 140 ppb, a fourfold improvement over the previous E821 measurement at BNL. The measurement is extracted from an analysis of the modulation of the rate of higher- energy positrons from muon decays, detected by 24 calorimeters and 3 straw tracking detec- tors. The straw tracking detectors will be used to measure the beam profile, cross-calibrate the calorimeter, identify pile-up and track muons lost from the storage region. In addition, a tracker measurement of the vertical modulation of positrons will be used for a search for an electric dipole moment signal. Herein, the readout electronics of the straw tracker are described. Ana- logue signals from the straws are amplified, shaped and discriminated by custom ASDQ ASICs and the digital output is passed to an FPGA-based TDC which records the hit time with a resolu- tion of 0.6 ns. The hits are buffered and event records are created by FC7 and AMC13 modules in a MicroTCA crate, which are then passed into the MIDAS event-builder and data acquisition system.