[en] A compact and fast electromagnetic calorimeter prototype was designed, built, and tested in preparation for a next-generation, high-rate muon (g-2) experiment. It uses a simple assembly procedure: alternating layers of 0.5-mm-thick tungsten plates and 0.5-mm-diameter plastic scintillating fiber ribbons. This geometry leads to a detector having a calculated radiation length of 0.69 cm, a Moliere radius of 1.73 cm, and a measured intrinsic sampling resolution term of (11.8±1.1)%/√(E(GeV)), in the range 1.5-3.5 GeV. The construction procedure, test beam results, and GEANT-4 comparative simulations are described.

[en] We report a measurement of the positive muon lifetime to a precision of 1.0 ppm; it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2x10¹² decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τ_μ⁺(MuLan)=2 196 980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G_F(MuLan)=1.166 378 8(7)x10^-5 GeV^-2 (0.6 ppm). It is also used to extract the μ^-p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g_P.

[en] Possible deterioration of anode sense wires used in a hydrogen-filled neutron detector is investigated. Wires were loaded with free weights and put into a wire detector environment. Stainless steel, tungsten, and platinum wires did not break after exposure to charge equivalent to many wire lifetimes. Furthermore, exposure to hydrogen gas caused no noticeable surface degradation or change in wire yield strength

[en] The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, τ_μ=2.197 013(24) μs, is in excellent agreement with the previous world average. The new world average τ_μ=2.197 019(21) μs determines the Fermi constant G_F=1.166 371(6)x10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P