Next generation muon g-2 experiment at FNAL

Abstract

I report on the progress of two new muon anomalous magnetic moment experiments, which are in advanced design and construction phases. The goal of Fermilab E989 is to reduce the experimental uncertainty of a μ from Brookhaven E821 by a factor of 4; that is, δa μ ∼ 16 × 10 −11 , a relative uncertainty of 140 ppb. The method follows the same magic-momentum storage ring concept used at BNL, and pioneered previously at CERN, but muon beam preparation, storage ring internal hardware, field measuring equipment, and detector and electronics systems are all new or upgraded significantly. In contrast, J-PARC E34 will employ a novel approach based on injection of an ultra-cold, low-energy, muon beam injected into a small, but highly uniform magnet. Only a small magnetic focusing field is needed to maintain storage, which distinguishes it from CERN, BNL and Fermilab. E34 aims to roughly match the previous BNL precision in their Phase 1 installation.

Hadronic light-by-light scattering in the anomalous magnetic moment of the muon

“…a hlbl µ | π 0 ,VMD = 57.0 • 10 −11 [10]; however, the uncertainty of the result is now much better known. 4 The direct lattice calculation of HLbL in (g − 2) µ…”

“…1. The new E989 experiment at Fermilab is underway (see [4] and the presentation of A. Driutti at this conference), with the stated goal of improving the precision of the measurement by a factor four, and the E34 experiment at J-PARC (see [5] and the presentation of T. Mibe at this conference) plans to achieve a similar precision with a very different technique. It is therefore essential to improve the precision of the predictions for the hadronic contributions in order to enhance the new-physics sensitivity of the upcoming experimental results.…”

Lattice QCD and the anomalous magnetic moment of the muon

“…The need to obtain more precise results for the HVP and HLbL contributions is underlined by the fact that the sensitivity of future experimental measurements of a µ will exceed the uncertainties associated with HVP and HLbL. Two new experiments with very different setups are expected to improve the precision of the experimental determination by a factor four: The E989 experiment at Fermilab [47,48] uses the original storage ring of the older BNL experiment. A number of technical improvements will provide a much cleaner muon sample, better magnetic field calibration and more efficient detectors to record the muon decay.…”