Precise Qβ measurements for A = 91 to 93 mass chains

The Qβ values of 91–93Rb, 91–93Sr, and 92–93Y were measured using mass-separated Rb sources obtained from an on-line isotope separator. A ΔE–E detector telescope consisting of a 300 μm × 300 mm2 Si ΔE- and a 15 mm × 500 mm2 Ge(HP) E detector was used. Results are in general agreement with recently published values but some discrepancies are indicated.