Longitudinal momentum distribution of monoenergetic electron neutrinos from orbital electron capture decay

N. Winckler1,2, F. Nolden2, D. R. Atanasov3, P. Buehler4, V. Ivanova2, M. S. Sanjari2,5, D. Shubina1, T. Yamaguchi6 for the Two-Body Weak Decay Collaboration (TBWD@GSI) 1MPI-K, Heidelberg; 2GSI, Darmstadt; 3St. K. Ohridski University, Sofia; 4SMI, Vienna; 5J. W. Goethe Universitaet, Frankfurt; 6Saitama University, Saitama Schottky Mass Spectrometry (SMS) is frequently used for mass and lifetime measurements at the Experimental Storage Ring (ESR). This method is non-destructive and can be sensitive to single stored ions with a charge q > 30. This has offered the possibility to perform Single Ion Decay Spectroscopy (SIDS) where, for example, the orbital electron capture (EC) decay branch of hydrogen-like (Hlike) I, Pr and Pm has been investigated [1, 2]. Such a method requires a good sensitivity, i.e. a proper time resolution with an acceptable signal-to-noise ratio. Therefore a new dedicated resonant Schottky pick-up with higher sensitivity – by a factor of about 100 – has been developed and installed in spring 2010 at the ESR[3, 4]. The combination of this new detection system with a proper spectral analysis based on the multitaper method [5] has led to very successful results for SIDS experiments. Figure 1 illustrates the achievement of the method as the example of an EC-decay of a single H-like Pm ion.