A precision experiment to investigate long-lived radioactive decays

作者：Angevaare J R; Barrow P; Baudis L; Breur P A; Brown A; Colijn A P; Cox G; Gienal M; Gjaltema F; Helmling Cornell A; Jones M; Kish A; Kurz M; Kubley T; Lang R F; Massafferri A; Perci R; Reuter C^*; Schenk D; Schumann M; Towers S

来源：Journal of Instrumentation, 2018, 13(07): P07011.

DOI：10.1088/1748-0221/13/07/P07011

• Detector control systems (detector and experiment monitoring and slow-control systems, architecture, hardware, algorithms, databases)
• Gamma detectors (scintillators, CZT, HPG, HgI etc)
• Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators)

Radioactivity is understood to be described by a Poisson process, yet some measurements of nuclear decays appear to exhibit unexpected variations. Generally, the isotopes reporting these variations have long half lives, which are plagued by large measurement uncertainties. In addition to these inherent problems, there are some reports of time-dependent decay rates and even claims of exotic neutrino-induced variations. We present a dedicated experiment for the stable long-term measurement of gamma emissions resulting from beta decays, which will provide high-quality data and allow for the identification of potential systematic influences. Radioactive isotopes are monitored redundantly by thirty-two 76 mm x 76 mm NaI(Tl) detectors in four separate temperature-controlled setups across three continents. In each setup, the monitoring of environmental and operational conditions facilitates correlation studies. The deadtime-free performance of the data acquisition system is monitored by LED pullers. Digitized photomultiplier waveforms of all events are recorded individually, enabling a study of time-dependent effects spanning microseconds to years, using both time-binned and unbinned analyses. We characterize the experiment's stability and show that the relevant systematics are accounted for, enabling precise measurements of effects at levels well below O(10(-4)).

• 出版日期2018-7