Direct Measurement of the Mass Difference ofHo163andDy163

Abstract

The atomic mass difference of (163)Ho and (163)Dy has been directly measured with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. Our measurement has solved the long-standing problem of large discrepancies in the Q value of the electron capture in (163)Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7σ to 2833(30(stat))(15(sys)) eV/c(2). With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude.

A White Paper on keV sterile neutrino Dark Matter

“…This measurement has been able to strongly reduce the uncertainties on Q EC . The value that has been obtained, Q EC = (2.833 ± 0.030 stat ± 0.015 syst ) keV [926] is in very good agreement with the Q EC -value obtained by the analysis of calorimetrically measured 163 Ho spectra. In order to remove systematic uncertainties, at a few eV level, on the Q EC -value as determined by the analysis of the calorimetrically measured spectra, which could derive from solid state effects, an independent measurement at 1 eV precision level is of outmost importance.…”

“…The precise knowledge of the Q EC is of outmost importance not only for the investigation of the "standard" effective electron neutrino mass, but also to define with high precision the value of the heavy neutrino mass m 4 through the difference between the position of the possible kink and the endpoint of the spectrum. The uncertainties on the Q EC have already been strongly reduced by the measurements performed using Penning traps [926] and this achievement paved the way for future experiments aiming to the 1 eV precision. 163 Ho EC + pu 163 Ho EC Figure 50.…”

“…With experiments based on 163 Ho it appears possible to reach, for the electron neutrino mass, the same sensitivity which tritium based experiments, as KATRIN [129,897] can achieve for the electron anti-neutrino mass. 163 Ho is considered the best candidate among all nuclides undergoing electron capture processes to be used in an experiment for the investigation of the neutrino mass because of its extremely low energy available to the decay, Q EC = 2.833 ± 0.030 stat ± 0.015 syst keV [926,927]. Such a low Q EC allows for a reasonable fraction of counts in the endpoint region of the spectrum to be analyzed for identifying effects due to a finite effective neutrino mass.…”

Light sterile neutrino sensitivity of 163Ho experiments

“…Recently, the Q-value has been precisely determined by Penning trap mass spectrometry to be Q = 2833 ± 30 stat ± 15 syst eV [98]. At the present knowledge, this is the lowest Q for all nuclides undergoing electron capture processes.…”

Determination of the neutrino mass in 163 Ho

“…For the capture 163 Holmium + bound Electron → excited 163 Dysprosium * + N eutrino (1) the decay energy Q was obtained by a Penning trap measurement by Eliseev et al [19] in the MPI in Heidelberg ( [20,21,22]). …”