SciPost Phys. Proc. 5, 007 (2021) ·
published 6 September 2021
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SINDRUM-I was the first nearly 4 spectrometer at SIN. It was initially designed to 9 search for the forbidden decay + ! e+ee+ , but also successfully studied various 10 other processes with high precision. The upper limit obtained for the branching ratio of B!3e = (+ ! e+ee+ )= (+ ! e+e¯ 11 ) < 1.0 1012(90% CL) from 1988 is still the best. The first statistically significant observation of the rare decay + ! e+ee+e¯ 12 , achieved in 1985, yielded a branching ratio of B13 !3e2 = (3.40.20.2)105. Several 14 othermeasurements of rare decays were undertaken: the first observation of the -decay 15 + !e+eee+ resulted in (+ !e+eee+ )= (+ !+ ) = (3.2 0.5 0.2) 109, 16 also still the best measurement; and a determination of the ratio of the weak axial- to 17 vector-form factor FA=FV = (0.7 0.5), resolving an ambiguity. In addition, upper limits 18 for + ! e+ and + ! e+e with subsequent decay ! e+e (search for "massless" Goldstone bosons) and 0 !e+e 19 < 1.3 107 were obtained.
Prof. Grab: "“The SINDRUM-I Experiment” ==..."
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