CANTON-μ Proposal: A Next-Generation Muon $g\!-\!2$ Measurement at Sub-0.1 ppm Precision

Abstract

We propose a next-generation precision measurement of the muon anomalous magnetic moment ($g-2$) at the High Intensity Heavy-Ion Accelerator Facility (HIAF) in Huizhou, China. The project, named CANTON-$μ$ (Coherent Anomalous magNetic momenT ObservatioN with muon), describes novel experimental approaches based on HIAF's unique capability to produce intense pulsed muon beams at the GeV scale, particularly for negative-muon polarity. These approaches incorporate innovative focusing concepts such as the sector-magnet and weak-focusing ring designs, complemented by advanced magnetic-field calibration methods including a polarized-proton co-magnetometer. This independent measurement with distinct systematics is designed to achieve a precision of 0.1 ppm in Phase 1, matching the latest Fermilab result for $μ^+$, and 0.05 ppm in Phase 2 with the HIAF upgrade. Such precision will provide an exceptionally sensitive test of the Standard Model and a powerful probe of New Physics and CPT symmetry.

Figures (7)

• Figure 1: Status of muon $g\!-\!2$ Standard Model predictions and experimental measurements.
• Figure 2: The layout of HIAF, adapted from Fig. 1 in Ref. Xiaohong:2018weu.
• Figure 3: Positive (left) and negative (right) particles at the HIAF production target from proton at 9.3 GeV.
• Figure 4: Simulated beam profiles of purified positive muons at 3.1 GeV/c (left) and the momentum spread (right), evaluated at the exit of the HFRS.
• Figure 5: Purified muon flux at the exit of the HFRS as a function of muon momentum. Each point represents the measured muon intensity for a specific momentum bin (left: negative muon; right: positive muon).