Measuring gP with laser polarized 3He

The LANL-Princeton-Syracuse collaboration has developed an efficient new method for polarizing muonic helium. Unpolarized muons stop in unpolarized helium containing a sufficient density of laser-polarized Rb atoms to cause charge exchange and spin exchange reactions. The result is average polarizations in muonic 3He of 27%. This method is suitable for studies of the spin dependence of the reaction μ- + 3He → 3H + ν, which is sensitive to the induced psuedoscalar coupling gP. The collaboration is developing a helium ion chamber that, in addition to serving as a target, will also detect the 1.9 MeV recoil tritons produced by muon capture and measure their direction relative to the muon polarization. A prototype chamber has detected the reaction n + 3He → p + 3H, and has achieved reasonable energy resolution and sensitivity to track direction. Tests of this chamber at LAMPF indicate that background rates are acceptable