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ADC Nonlinearity Correction for the Majorana Demonstrator
Imperfections in analog-to-digital conversion (ADC) cannot be ignored when signal digitization requirements demand both wide dynamic range and high resolution, as is the case for the Majorana Demonstrator 76Ge neutrinoless double-beta decay search. Enabling the experiment's high-resolution spectral analysis and efficient pulse shape discrimination required careful measurement and correction of ADC nonlinearities. A simple measurement protocol was developed that did not require sophisticated equipment or lengthy data-taking campaigns. A slope-dependent hysteresis was observed and characterized. A correction applied to digitized waveforms prior to signal processing reduced the differential and integral nonlinearities by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay Q value
Majorana Demonstrator Data Release for AI/ML Applications
The enclosed data release consists of a subset of the calibration data from
the Majorana Demonstrator experiment. Each Majorana event is accompanied by raw
Germanium detector waveforms, pulse shape discrimination cuts, and calibrated
final energies, all shared in an HDF5 file format along with relevant metadata.
This release is specifically designed to support the training and testing of
Artificial Intelligence (AI) and Machine Learning (ML) algorithms upon our
data. This document is structured as follows. Section I provides an overview of
the dataset's content and format; Section II outlines the location of this
dataset and the method for accessing it; Section III presents the NPML Machine
Learning Challenge associated with this dataset; Section IV contains a
disclaimer from the Majorana collaboration regarding the use of this dataset;
Appendix A contains technical details of this data release. Please direct
questions about the material provided within this release to [email protected]
(A. Li).Comment: Zenodo DOI: https://doi.org/10.5281/zenodo.825702
Constraints on the decay of Ta
Ta is a rare nuclear isomer whose decay has never been observed. Its
remarkably long lifetime surpasses the half-lives of all other known
and electron capture decays due to the large K-spin differences and small
energy differences between the isomeric and lower energy states. Detecting its
decay presents a significant experimental challenge but could shed light on
neutrino-induced nucleosynthesis mechanisms, the nature of dark matter and
K-spin violation. For this study, we repurposed the MAJORANA DEMONSTRATOR, an
experimental search for the neutrinoless double-beta decay of Ge using
an array of high-purity germanium detectors, to search for the decay of
Ta. More than 17 kilograms, the largest amount of tantalum metal ever
used for such a search was installed within the ultra-low background detector
array. In this paper we present results from the first year of Ta data taking
and provide an updated limit for the Ta half-life on the different
decay channels. With new limits up to 1.5 x years, we improved
existing limits by one to two orders of magnitude. This result is the most
sensitive search for a single and electron capture decay ever achieved