Teilchenphysik ohne Beschleuniger (Non Accelerator Particle Physics)

Experimental and theoretical research in the areas of
Double Beta Decay, Dark Matter Searches and Physics beyond the Standard Model


Nr. 1 - A New Experimental Limit for the Stability of the Electron

Nr. 1: Please click here to print the pdf file
of our NEW LIMIT for the Stability of the ELECTRON
Physics Letters B 644 (2007) 109-118:

H.V. Klapdor-Kleingrothaus, I.V. Krivosheina and I.V. Titkova

"A New Experimental Limit for the Stability of the Electron"

-------- Abstract --------
A lower limit of > 1.22 x 1026years (68% c.l.) has been determined
for the mean life time of electron decay via the branch e- ---> gamma + nue.
The limit was deduced from the spectra measured in the period 1995-2003
with the full set-up of 5 enriched 76Ge detectors
of the HEIDELBERG-MOSCOW beta-beta experiment in the Gran-Sasso underground laboratory.
One of the detectors, and the setup 1 consisting of four detectors show an indication
of a signal on a 1.4 sigma C.L.
The best limit given by a single detector is 1.93 x 1026 y.
The result is the by far sharpest limit obtained with Ge detectors.
When comparing it with other limits, e.g. that from BOREXINO \cite{Borex02}
it may be essential to note that the present limit has been deduced
from the raw data without any treatment of the background.
Combined with the best laboratory limit on the photon mass
it gives the following restriction for charge nonconservation:
epsilon_e nu gamma < 0.86 x 10-98 (68% c.l.) or < 1.14 x 10-97 (90% c.l.).

-------- Abstract --------

HM-El-Decay Setup HM-El-Decay Setup
"Left: Geometry of the setup 1 of the HEIDELBERG-MOSCOW experiment,
containing four of five enriched detectors (detectors 1,2,3,5).
The germanium detectors (grey) are mounted in copper cryostats (red).
The detector holder system consists of teflon (green) and vespel (yellow).
Right: Spectrum in the energy region of interest for e- decay
(counts) over the full measuring time for setup 1
of the HEIDELBERG-MOSCOW experiment (see abstract). "

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Last modification (I.Krivosheina): 25/08/2009