39 research outputs found
Measurements of low decay energies of beta-processes using Penning traps
No full textTwo topics of fundamental physics are considered where nuclides with a low beta-decay energy are of high interest, namely nuclear astrophysics and neutrino physics. A few relevant ground-to-ground beta-transitions were addressed by Penning-trap mass spectrometry (PT-MS), employing the Shiptrap (GSI, Darmstadt) and Isoltrap (CERN, Geneva) facilities.
In nuclear astrophysics the decay energy of a nuclide is an important spectroscopic parameter. Thus, in the case of the pure s-process nuclide 123Te, it was shown that when its decay energy is accurately and precisely known, the complete decay scheme in a hot stellar environment can be reliably reconstructed. It is shown that at typical s-process
conditions the half-life of 123Te can be by many orders of magnitude shorter than the terrestrial value. This circumstance may be used, for example, for tests of astrophysical models in the A = 123 mass region.
In neutrino physics, low-energy beta-transitions can be used for determination of the neutrino rest mass. The decay energies (Q-values) of 131Cs and 202Pb were determined. It turned out that the nuclide 202Pb can hardly be used for the neutrino mass determination due to its too high Q-value, whereas 131Cs can be confidently excluded from the consideration since the examined beta-transition is energetically forbidden. The directly measured Q-value of
187Re has shown that on the level of our present accuracy of 33 eV there are no unexpected systematic effects inherent in cryogenic microcalorimetry (CM), which was used for the
beta-spectra acquisition of 187Re. A specific problem in neutrino physics is the existence of sterile neutrinos, especially those which can contribute to the so-called Warm Dark Matter. It is shown that the combined efforts of PT-MS and CM may contribute to the keV sterile neutrino search in electron capture in a variety of nuclides
The electron capture in Ho experiment – ECHo
No full textNeutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of theH β-decay and theHo electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture inHo experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclideHo. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure theHo EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pureHo samples, the identification and suppression of background sources as well as the precise parametrization of theHo EC spectrum are of utmost importance. The high-energy resolutionHo spectra measured with the first MMC prototypes with ion-implantedHo set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBqHo will allow to reach a neutrino mass sensitivity below 10 eV/c. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBqHo embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass
Detection of abnormal process behavior in copper solvent extraction by Hotelling T2 and squared prediction error control chart
No full textOnce a multivariate model is developed, it can be combined with tools and techniques from univariate statistical process control to form multivariate statistical process control tools. It allows development of advanced process monitoring strategies. In the current study, copper plant history data with multiple variables was successfully treated by principal component analysis to detect abnormal process behavior, particularly, in copper solvent extraction. The multivariate model was based on the concentration levels of main process metals recorded by the industrial on-stream x-ray fluorescence analyzer. Normal operating conditions were defined through control limits that were assigned to Hotelling T2 values on x-axis and to squared prediction error values on y-axis. Samples that were beyond the limits were classified as either systematic or random errors, or outliers. Model testing showed successful application of control limits to detect abnormal behavior of copper solvent extraction process as early warnings. Compared to the conventional univariate techniques of analyzing one variable at a time, the proposed model allows to detect on-line a process failure summarizing information from all process variables simultaneously. The proposed methodology was combined with on-line quality monitoring tool developed by VTT, Technical Research Center of Finland, to visualize the results. Thus, the proposed approach has a potential in on-line industrial instrumentation providing fast, robust and cheap application with automation abilities.</p
Low energy nuclear isomers
No full textThis paper aims to compile and to structure information about the low energy nuclear isomerism
and its use in different areas of convergent sciences. A phenomenon of isomerism investigated in
nuclear physics is of a great interest for different areas of science. An analysis has been carried
out for most interesting issues of physics, which could be overcome in the nearest future if nuclear
isomerism is used. As an example the long standing dilemma of gamma-laser, which can be based
on the isomeric states, and a low-energy state of 229Th are considered. Unprecedented the low energy
nuclear excitation of the isomer makes possible its use to create a new record on accuracy and
stability of the frequency standard (time). The place of low energy states in some astrophysical
processes and in nuclear cosmochronology is discussed as well. It is shown how these low energy
nuclear excited states, populated in high-temperature stellar conditions, significantly affect the
effective rate of decay of astrophysical chronometers. Requirements of precise determination of
the energies of the isomeric levels can be successfully provided by mass spectrometry using the
Penning ion traps. Description of them is given in a separate paragraph. Refs 32. Figs 6
On the keV sterile neutrino search in electron capture
No full textA joint effort of cryogenic microcalorimetry (CM) and high-precision Penning-trap mass spectrometry (PT-MS) in investigating atomic orbital electron capture (EC) can shed light on the possible existence of heavy sterile neutrinos with masses from 0.5 to 100 keV. Sterile neutrinos are expected to perturb the shape of the atomic de-excitation spectrum measured by CM after a capture of the atomic orbital electrons by a nucleus. This effect should be observable in the ratios of the capture probabilities from different orbits. The sensitivity of the ratio values to the contribution of sterile neutrinos strongly depends on how accurately the mass difference between the parent and the daughter nuclides of EC transitions can be measured by, for example, PT-MS. A comparison of such probability ratios in different isotopes of a certain chemical element allows one to exclude many systematic uncertainties, and thus could make feasible a determination of the contribution of sterile neutrinos on a level below 1%. Several electron capture transitions suitable for such measurements are discussed
Direct Measurement of the Mass Difference of Ho 163 and Dy 163 Solves the Q -Value Puzzle for the Neutrino Mass Determination
No full textThe atomic mass difference of 163Ho and 163Dy has been directly measured with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. Our measurement has solved the long-standing problem of large discrepancies in the Q value of the electron capture in 163Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7σ to 2833(30stat)(15sys) eV/c2. With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude
Direct determination of the atomic mass difference of and for neutrino physics and cosmochronology
No full textFor the first time a direct determination of the atomic mass difference of 187Re and 187Os has been performed with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. The obtained value of 2492(30stat)(15sys) eV is in excellent agreement with the Q values determined indirectly with microcalorimetry and thus resolves a long-standing discrepancy with older proportional counter measurements. This is essential for the determination of the neutrino mass from the β- decay of 187Re as planned in future microcalorimetric measurements. In addition, an accurate mass difference of 187Re and 187Os is also important for the assessment of 187Re for cosmochronology
Fast silicon carbide MOSFET based high-voltage push–pull switch for charge state separation of highly charged ions with a Bradbury–Nielsen gate
No full textIn this paper we report on the development of a fast high-voltage switch,
which is based on two enhancement mode N-channel Silicon Carbide Metal Oxide
Semiconductor Field-Effect Transistors in push-pull configuration. The switch
is capable of switching high voltages up to 600 V on capacitive loads with rise
and fall times on the order of 10 ns and pulse widths 20 ns. Using this
switch it was demonstrated that from the charge state distribution of bunches
of highly charged ions ejected from an electron beam ion trap with a specific
kinetic energy, single charge states can be separated by fast switching of the
high voltage applied to a Bradbury-Nielsen Gate with a resolving power of about
100
A White Paper on keV sterile neutrino dark matter
No full textWe present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos
The decay energy of the pure s-process nuclide 123Te
No full textA direct and high-precision measurement of the mass difference of 123Te and 123Sb has been performed with the Penning-trap mass spectrometer SHIPTRAP using the recently introduced phase-imaging ion-cyclotron-resonance technique. The obtained mass difference is 51.912(67) keV/c2. Using the masses of the neutral ground states and the energy difference between the ionic states an effective half-life of 123Te has been estimated for various astrophysical conditions. A dramatic influence of the electron capture process on the decay properties of 123Te in hot stellar conditions has been discussed
