Klapdor's claim for the observation of the neutrinoless double beta-decay of Ge-76. Analysis and corrections

TL;DR

This paper critically reanalyzes Heidelberg-Moscow data claiming to observe neutrinoless double beta-decay of Ge-76, revealing overlapping gamma peaks and background effects that challenge the original interpretation.

Contribution

It provides a detailed correction and reinterpretation of previous experimental data, questioning the evidence for neutrinoless double beta-decay in Ge-76.

Findings

Observed spectrum peaks are due to overlapping gamma lines.

Background gamma peaks at 2035.5 keV and 2039.5 keV confirmed.

The 2037.5 keV line may be the actual decay signal.

Abstract

Heidelberg-Moscow Collaboration experimental data [1-4] with the claim for the observation of the neutrinoless double beta-decay of Ge-76 has been carefully analyzed. The analysis gave an evidence that the observed 2039 kev line in the full spectrum was produced by overlapping of three unresolved peaks: ~2035.5 kev, ~2037.5 kev and ~2039.5 kev. It was indicated that the 2035.5 kev and 2039.5 kev peaks were produced by the double-coincidences of gamma-quanta in the detectors. Existence of the two background gamma-peaks at ~2035.5 kev and ~2039.5 kev was confirmed by an analysis of the background measurements with low-background Ge detectors with an active shielding [5-7]. The 2037.5 kev line could be the expected 2{\beta}0{\nu}-decay transition of 76Ge according to the results of the improved pulse-shape analysis. Position of the line, 2037.56+/-0.56(stat)+/-1.2(syst) kev [4], was slightly below the expected, E2{\beta}=2039.0+/-0.05 kev [8], but still within a limit for poor statistics. The most accurate value of its intensity was extracted from the 51.39 kg \cdot y data with PSA: number of events 12.4+/-3.7 and T1/2=1.98 \cdot 1025 years [2,3].