TY - JOUR

T1 - Search for resonant enhancement of neutrinoless double-electron capture by high-precision Penning-trap mass spectrometry

AU - Novikov, Yu N.

AU - Blaum, K.

PY - 2012/12/1

Y1 - 2012/12/1

N2 - The search for neutrinoless double-electron capture can be a good alternative to the neutrinoless double-beta-decay experiments in shedding light on such aspects of neutrino physics as the neutrino type, non-conservation of the total lepton charge and magnitude of the effective Majorana neutrino mass. The probability of neutrinoless double-electron capture can be resonantly enhanced by some orders of magnitude. Although the phenomenon of the resonant enhancement was predicted some decades ago, the search for resonantly enhanced neutrinoless double-electron-capture transitions was hampered by a lack of precise experimental values of the atomic mass differences of the transition initial and final states. Only recent progress in high-precision Penning-trap mass spectrometry has finally provided suitable means for a determination of atomic masses with a sufficient precision and thus given rise to the experimental campaign for a search for resonantly enhanced transitions. In this article, after an introduction to the theory of neutrinoless double-electron capture and the Penning-trap technique, a review is given on the results of systematic very precise direct Penning-trap measurements of the atomic mass differences of the nuclides which can undergo double-electron capture. The mass differences of 14 nuclear pairs have already been determined with a typical uncertainty of tens to a few hundreds of eV. Partial or even full resonant enhancement of the neutrinoless double-electron-capture probability has been discovered for 152Gd and 156Dy. In 156Dy a multiple resonance phenomenon has been revealed. For some transitions the half-lives have been estimated (152Gd, 164Er, 180W, 156Dy).

AB - The search for neutrinoless double-electron capture can be a good alternative to the neutrinoless double-beta-decay experiments in shedding light on such aspects of neutrino physics as the neutrino type, non-conservation of the total lepton charge and magnitude of the effective Majorana neutrino mass. The probability of neutrinoless double-electron capture can be resonantly enhanced by some orders of magnitude. Although the phenomenon of the resonant enhancement was predicted some decades ago, the search for resonantly enhanced neutrinoless double-electron-capture transitions was hampered by a lack of precise experimental values of the atomic mass differences of the transition initial and final states. Only recent progress in high-precision Penning-trap mass spectrometry has finally provided suitable means for a determination of atomic masses with a sufficient precision and thus given rise to the experimental campaign for a search for resonantly enhanced transitions. In this article, after an introduction to the theory of neutrinoless double-electron capture and the Penning-trap technique, a review is given on the results of systematic very precise direct Penning-trap measurements of the atomic mass differences of the nuclides which can undergo double-electron capture. The mass differences of 14 nuclear pairs have already been determined with a typical uncertainty of tens to a few hundreds of eV. Partial or even full resonant enhancement of the neutrinoless double-electron-capture probability has been discovered for 152Gd and 156Dy. In 156Dy a multiple resonance phenomenon has been revealed. For some transitions the half-lives have been estimated (152Gd, 164Er, 180W, 156Dy).

UR - http://www.scopus.com/inward/record.url?scp=84870415871&partnerID=8YFLogxK

U2 - 10.1088/0954-3899/39/12/124003

DO - 10.1088/0954-3899/39/12/124003

M3 - Article

AN - SCOPUS:84870415871

VL - 39

JO - Journal of Physics G: Nuclear and Particle Physics

JF - Journal of Physics G: Nuclear and Particle Physics

SN - 0954-3899

IS - 12

M1 - 124003

ER -