Search results for "Electron Capture"
showing 10 items of 90 documents
A novel experimental system for the KDK measurement of the 40K decay scheme relevant for rare event searches
2020
Potassium-40 ($^{40}$K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. $^{40}$K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of argon-40 has never been measured, which can cause difficulty in interpreting certain results or can lead to lack of precision depending on the field and analysis technique. The KDK (Potassium (K) Decay (DK)) collaboration is measuring this decay. A composite method has a silicon drift detector with an enriched, thermally deposited $^{40}$K source …
Excess electronic recoil events in XENON1T
2020
We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 t-y and an unprecedentedly low background rate of $76\pm2$ events/(t y keV) between 1 and 30 keV, the data enables sensitive searches for solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4$\sigma$ significance, and a 3D 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by $g_{ae}<3.8 \times 10^{-12}$,…
Reactive and organic halogen species in three different European coastal environments
2005
We present results of three field campaigns using active longpath DOAS (Differential Optical Absorption Spectroscopy) for the study of reactive halogen species (RHS) BrO, IO, OIO and I2. Two recent field campaigns took place in Spring 2002 in Dagebüll at the German North Sea Coast and in Spring 2003 in Lilia at the French Atlantic Coast of Brittany. In addition, data from a campaign in Mace Head, Ireland in 1998 was partly re-evaluated. During the recent field campaigns volatile halogenated organic compounds (VHOCs) were determined by a capillary gas chromatograph coupled with an electron capture detector and an inductively coupled plasma mass spectrometer (GC/ECD-ICPMS) in air and wat…
Nuclear matrix elements for rare decays
2010
Abstract Neutrinoless double electron capture ( 0 ν ECEC) is being vigorously investigated because of the possibility of it telling us something about the absolute mass scale of the neutrino. The resonant 0 ν ECEC is particularly interesting due to the potentially huge enhancement of its decay rate by a resonance condition. Recently the mass differences of two atom pairs were measured in order to study the enhancement of the 0 ν ECEC rates of 74Se and 112Sn. The associated nuclear matrix elements were also evaluated. The neutrino mass can also be detected by using beta decays with low Q values. Related to this we have investigated the second-forbidden decay branch of 115In with its ultra-lo…
High-precision electron-capture Q value measurement of 111In for electron-neutrino mass determination
2022
A precise determination of the ground state $^{111}$In ($9/2^+$) electron capture to ground state of $^{111}$Cd ($1/2^+$) $Q$ value has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. A value of 857.63(17) keV was obtained, which is nearly a factor of 20 more precise than the value extracted from the Atomic Mass Evaluation 2020 (AME2020). The high-precision electron-capture $Q$ value measurement along with the nuclear energy level data of 866.60(6) keV, 864.8(3) keV, 855.6(10) keV, and 853.94(7) keV for $^{111}$Cd was used to determine whether the four states are energetically allowed for a potential ultra-low $Q$-value $\beta^{}$ decay or electron-capture deca…
Critical study of and improvements in chromatographic methods for the analysis of type B trichothecenes
2001
Various analytical methods used in the analysis of type B trichothecenes (deoxynivalenol, nivalenol, 3- and 15-acetyldeoxynivalenol) in cereals were compared and optimised in this work. These methods use either GC-electron-capture detection (ECD) of trimethylsilyl, trifluoroacetyl and heptafluorobutyryl derivatives or HPLC with UV or photodiode array detection of analytes. A new HPLC procedure using fluorescence detection prior derivatisation with coumarin-3-carbonyl chloride has been also tested. Five extraction solvents and two solid-phase extraction cartridges (silica, Florisil) plus a especial clean-up column (MycoSep 225) were compared in order to obtain the best recovery of the mycoto…
Electron capture decay of116Inand nuclear structure of doubleβdecays
1998
Quasiparticle-random-phase-approximation (QRPA) calculations of double $\ensuremath{\beta}$ decays have not been able to reproduce data in the $A=100$ system. We propose the $A=116$ system---because of its smaller deformation---as a simpler system to test QRPA calculations. We present results of two experiments we performed, which determine the electron-capture-decay branch of ${}^{116}\mathrm{In}$ to be $(2.27\ifmmode\pm\else\textpm\fi{}0.63)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}%$, from which we deduce $\mathrm{log}{ft=4.39}_{\ensuremath{-}0.15}^{+0.10}$. We present QRPA calculations and compare their predictions to experimental data. Finally we use these calculations to…
Trianionic gold clusters
2001
Using Penning-trap experiments and a shell-correction method incorporating ellipsoidal shape deformations, we investigate the formation and stability patterns of trianionic gold clusters. Theory and ex- periment are in remarkable agreement concerning appearance sizes and electronic shell eects. In contrast to multiply cationic clusters, decay of the trianionic gold clusters occurs primarily via electron autodetach- ment and tunneling through a Coulomb barrier, rather than via ssion. PACS. 36.40.Wa Charged clusters { 36.40.Qv Stability and fragmentation of clusters { 36.40.Cg Electronic and magnetic properties of clusters
Discovery of an Exceptionally Strong β -Decay Transition of F20 and Implications for the Fate of Intermediate-Mass Stars
2019
A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on ^{20}Ne in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of ^{20}Ne and ^{20}F, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupte…
Gigahertz Single-Electron Pumping Mediated by Parasitic States
2018
In quantum metrology, semiconductor single-electron pumps are used to generate accurate electric currents with the ultimate goal of implementing the emerging quantum standard of the ampere. Pumps based on electrostatically defined tunable quantum dots (QDs) have thus far shown the most promising performance in combining fast and accurate charge transfer. However, at frequencies exceeding approximately 1 GHz, the accuracy typically decreases. Recently, hybrid pumps based on QDs coupled to trap states have led to increased transfer rates due to tighter electrostatic confinement. Here, we operate a hybrid electron pump in silicon obtained by coupling a QD to multiple parasitic states, and achi…