Measured Decay Rates Research Articles

Photothermal and spectroscopic characterization of Tb3+-doped tungsten–zirconium–tellurite glasses

Among the glassy materials, tellurite glasses exhibit low phonon energy (∼780 cm−1), good mechanical stability, chemical durability, and high linear and nonlinear refractive indices, with a wide transmission window (typically 0.4–6.0 μm), which make them promising materials for photonic applications. In this work, tungsten–zirconium–tellurite glasses doped with several Tb3+ concentrations (0.1–4.0 mol. % Tb2O3) were prepared and characterized through absorption, emission, excitation spectra and fluorescence decay rate measurements. Only the green/yellow emission due to the 5D4 level was observed since the 5D3 was not observed in either the absorption or emission spectra due to cutoff absorption of the host matrix at ∼470 nm. A concentration quenching effect was observed in the 545 nm green emission (5D4 → 7F5) with a critical Tb3+ concentration of 6.2×1020 cm3 (1.7 mol. %). Thermal lens (TL) was performed in order to determine the thermo-optical properties of the glass such as thermal diffusivity (D ∼ 3.3×10−3 cm2/s) and optical path temperature coefficient (ds/dT ∼ 2.5 × 10−5 K−1). The energy transfer efficiency from the host matrix to the Tb3+ was estimated from excitation spectra as ∼3%, in agreement with TL measurements which indicate that nearly all absorbed energy is converted into heat for 488 nm excitation (7F6 → 5D4). Z-scan measurements in the cw regime indicate a dominant thermal nonlinearity in agreement with TL data. However, the fluorescence measurements in the Z-scan indicate a strong saturation of the green fluorescence attributed to the effect of excited state absorption.

Observation of finite-size-induced emission decay rates in self-assembled photonic crystals

We study the extent of spontaneous emission inhibition in self-assembled photonic crystals where the light path is routinely affected by unavoidable imperfections of the crystal and its finite-size. We discuss the role of finite-size effects that inadvertently modify the local density of optical states (LDOS) using time-resolved decay rate measurements from the single domains of real synthesized photonic crystals. We have obtained 34% contrast in the measured emission lifetimes at the stop gap wavelength in comparison to a wavelength outside the stop gap. We have shown a remarkable variation in the emission lifetimes at the stop gap for several domains across the sample which is nullified within a single domain. The results manifest wavelength-dependent linear scaling of lifetimes with the finite-size of the crystal domain. This is a signature of direct dependence of LDOS suppression on the crystal's finite-size which is also found to be in accordance with a recent theoretical model. The precise single-domain measurements result in a robust modification of lifetime in an otherwise weakly classified self-assembled photonic crystal.

Measuring lung mechanics of expiratory tidal breathing with non-invasive breath occlusion

Background and objectiveLung mechanics measurements provide clinically useful information about disease progression and lung health. Currently, there are no commonly practiced methods to non-invasively measure both resistive and elastic lung mechanics during tidal breathing, preventing the important information provided by lung mechanics from being utilised. This study presents a novel method to easily assess lung mechanics of spontaneously breathing subjects using a dynamic elastance, single-compartment lung model.MethodsA spirometer with a built-in shutter was used to occlude expiration during tidal breathing, creating exponentially decaying flow when the shutter re-opened. The lung mechanics measured were respiratory system elastance and resistance, separated from the exponentially decaying flow, and interrupter resistance calculated at shutter closure. Progressively increasing resistance was added to the spirometer mouthpiece to simulate upper airway obstruction. The lung mechanics of 17 healthy subjects were successfully measured through spirometry.ResultsN = 17 (8 female, 9 male) healthy subjects were recruited. Measured decay rates ranged from 5 to 42/s, subjects with large variation of decay rates showed higher muscular breathing effort. Lung elastance measurements ranged from 3.9 to 21.2 cmH_2O/L, with no clear trend between change in elastance and added resistance. Resistance calculated from decay rate and elastance ranged from 0.15 to 1.95 cmH_2Os/L. These very small resistance values are due to the airflow measured originating from low-resistance areas in the centre of airways. Occlusion resistance measurements were as expected for healthy subjects, and increased as expected as resistance was added.ConclusionsThis test was able to identify reasonable dynamic lung elastance and occlusion resistance values, providing new insight into expiratory breathing effort. Clinically, this lung function test could impact current practice. It does not require high levels of cooperation from the subject, allowing a wider cohort of patients to be assessed more easily. Additionally, this test can be simply implemented in a small standalone device, or with standard lung function testing equipment.

Charge-state conversion in nitrogen-vacancy centers mediated by an engineered photonic environment

The nitrogen-vacancy (NV) center in nanodiamonds has emerged as an excellent platform in quantum technologies due to its applications in spin manipulation and nanoscale sensing. However, their use is limited by the unavoidable charge-state conversion under optical pumping. In this study, we investigate the control of charge-state conversion in NV centers using an engineered photonic environment and thus change the available local density of optical states (LDOS). The spectral- and pump-dependent decay rate measurements are performed to study the redistribution of emission rates due to the change in LDOS and their effect on charge-state conversion. We have achieved an 8% enhancement of emission rate at the zero phonon line which is accompanied with a 10% suppression in the phonon sideband emission rate in the low-pump-power regime. In the high-pump-power regime, the charge-state conversion becomes inevitable and leads to the deterioration of LDOS-induced modification in the NV center emission lifetimes. The results are useful for efficient NV center spin readout and charge-state depletion microscopy utilizing reversible charge-state conversion.

Generalized Lomb\u2013Scargle analysis of mathrm {^{36}Cl} decay rate measurements at PTB and BNL

Recently Pomme et al. (Solar Phys 292:162, 2017) did an analysis of {^{36}hbox {Cl}} radioactive decay data from measurements at the Physikalisch-Technische Bundesanstalt (PTB), in order to verify the claims by Sturrock and collaborators of an influence on beta-decay rates measured at Brookhaven National Lab (BNL) due to the rotation-induced modulation of the solar neutrino flux. Their analysis excluded any sinusoidal modulations in the frequency range from 0.2 to 20/year. We carry out an independent analysis of the same PTB and BNL data, using the generalized Lomb–Scargle periodogram to look for any statistically significant peaks in the range from 0 to 14 per year, and by evaluating the significance of every peak using multiple methods. Our results for the PTB data are in agreement with those by Pomme et al. For BNL data, we do find peaks at some of the same frequencies as Sturrock et al., but the significance is much lower. All our analysis codes and datasets have been made publicly available.

Reference Models for Lithospheric Geoneutrino Signal

AbstractDebate continues on the amount and distribution of radioactive heat producing elements (i.e., U, Th, and K) in the Earth, with estimates for mantle heat production varying by an order of magnitude. Constraints on the bulk‐silicate Earth's (BSE) radiogenic power also places constraints on overall BSE composition. Geoneutrino detection is a direct measure of the Earth's decay rate of Th and U. The geoneutrino signal has contributions from the local ( 40%) and global ( 35%) continental lithosphere and the underlying inaccessible mantle ( 25%). Geophysical models are combined with geochemical data sets to predict the geoneutrino signal at current and future geoneutrino detectors. We propagated uncertainties, both chemical and physical, through Monte Carlo methods. Estimated total signal uncertainties are on the order of 20%, proportionally with geophysical and geochemical inputs contributing 30% and 70%, respectively. We find that estimated signals, calculated using CRUST2.0, CRUST1.0, and LITHO1.0, are within physical uncertainty of each other, suggesting that the choice of underlying geophysical model will not change results significantly, but will shift the central value by up to 15%. Similarly, we see no significant difference between calculated layer abundances and bulk crustal heat production when using these geophysical models. The bulk crustal heat production is calculated as 7 2 TW, which includes an increase of 1 TW in uncertainty relative to previous studies. Combination of our predicted lithospheric signal with measured signals yield an estimated BSE heat production of 21.5 10.4 TW. Future improvements, including uncertainty attribution and near‐field modeling, are discussed.

Liquid scintillator for search of double beta decay with Tin

Sn-124 is one of the double beta decay isotopes where no measurement of the 2νββ decay rate has been performed. The abundance of the isotope is 5.79%, fairly low, however it can be compensated for by the high loading potential of the natural isotope up to 10% into liquid scintillator without significant light quenching. This work presents results of the LAB based tin loaded liquid scintillator: stability, light yield and possible purification techniques.

High resolution energy-time of flight spectrometer: Dehydrogenation of fluorene cation as case study

Testing and performance validation of a new multipurpose time-of-flight mass spectrometer followed by an energy analyzer is presented. The instrument with high mass and energy resolution is primarily designed to study cations of polycyclic aromatic hydrocarbons (PAHs) and their dehydrogenation process. The energy correlated time-of-flight measurement is supplemented by Monte Carlo simulation to probe the dehydrogenation process in a relatively small PAH cation. The experiment is carried out on fluorene+ on a timescale of several microseconds. Fluorene cations with high internal energies were produced using UV multiphoton ionization. Specific n-photon processes leading to ionization as well as H-loss reaction were identified. The average value of dehydrogenation rate is estimated by fitting the measured data to the outcome of simulations. The quantification of H loss decay rate is in agreement with previously reported decay rate measurement. This corresponds to the internal energy available by inner valence electron emission caused by three photon process. The effectiveness of the instrument to access a range of decay rates (103–107 s−1) in a single measurement is demonstrated.

Single crystal HPGe (80%) versus BGO shielded CLOVER detector for high precision decay rate measurements: a comparative study

In this study, various detector configurations have been investigated in order to explore the optimal condition for decay rate measurements of radioactive samples using gamma spectroscopy technique. A limitation of detecting low energy gamma rays from decaying radioactive nuclei, is the Compton background which can be significantly reduced by rejecting Compton scattered events through active Bismuth germanate (BGO) shielding. On the other hand, for a CLOVER detector without BGO shielding, one can place the radioactive samples very close to the detector for enhancing geometrical efficiency. A single crystal High Purity Germanium (HPGe) detector can also be used for decay rate measurements. In order to measure the decay rate of nuclei decaying via gamma emission with reasonable intensity, optimal close geometry options have been investigated for various HPGe detector configurations.

Photoluminescence decay rate of an emitter layer on an Al nanocylinder array: effect of layer thickness

Photoluminescence (PL) of emitters on periodic arrays of plasmonic nanocylinders can be modulated largely by the interaction of the emitter with the plasmonic modes excited on the array. An energy transfer to metal, or nonresonant coupling of the emitters to high-order dark plasmonic modes, works as a nonradiative decay path to decrease the PL intensity. In this study, via PL decay rate measurements, we systematically investigated how the thickness of the emitter layer affected the energy transfer. An Eu complex was selected as an emitter, where Eu3+ acts as a light-emitting center with a high quantum yield. Thin layers of Eu complex showed an absorption coefficient of 3.4×104 cm−1, corresponding to the absorption length of 290 nm at a wavelength of 325 nm, i.e., the excitation wavelength used in this study. The thickness critically affected the energy transfer ratio, which was reduced as the thickness of the layers increased and was almost suppressed when the thickness was 1000 nm. The results suggest that there is an optimal thickness where PL enhancement is obtained with suppression of energy transfer.

Nonlinear characterization of ECGs in patients with Chagas’ disease**Partially supported by Consejo Nacional de Investigaciones Científicas y Tecnológicas, CONICIT under the grant G-97000675 and Vice-Rectorado de Investigación, Universidad Nacional San Agustin de Arequipa-Perú grant contract 15-2017-UNSA.

According to the World-Wide Organization of the Health, the number of people infected with the Tripanosoma Cruzi is considered between 6 and 8 million, causal agent of the Chagas’ disease , and in 550000 the people are expected to be exposed to the affectation risk. When concluding in 1983 a longitudinal epidemiologist study in patients with the disease evaluated every 3 years, the cardiac affectation: chronic Chagasic myocarditis (MCHC) increased from a 17% at the beginning of the study to a 49, 4% after 15 years. Previous studies of the variability of cardiac frequency (HRV) in patients with the Chagas’ disease, show alterations in the spectral indices of the HRV. A nonlinear modeling technique allows the definition of early risk markers in patients with Chagas’s disease and without any evidence of cardiac involvement evaluated by standard diagnostic test (CH1). We analyze ECGs by Holter recordings in patients with ECG alterations (CH2), patients without ECG alterations (CH1) who had positive serological findings for Chagas’ disease and healthy (Control) matched for sex and age. Two ECGs were digitized for each volunteer, one begins at supine position and the other at orthostatic position. The technique applied is based upon quantitative comparison of the evolution from similar ECGs Sub segments, and a measure of the predictability decay rate were calculated for each register. We did find significant differences among Control and CH2 during supine and also standing with high sensibility and specificity in the early detection of cardiac involvement. It is suggested that these alterations are very early autonomic disturbances in patients without ECG alterations (CH1) that could be useful to enhance risk stratification.

Critical analysis of decay rate measurement methodology

In modeling studies, estimation of microorganisms kinetic parameters set is a key element for proper model operation and predictability. Nitrification process is very often, a crucial element of the wastewater treatment systems as bacteria responsible for ammonium and nitrite oxidation are slow growing microorganisms, making whole nitrification process vulnerable to external factors i.e. temperature, inhibition and load fluctuations. Growth and decay rate of nitrifiers decide about amount nitrifying biomass in the wastewater treatment plants, thus the nitrification efficiency. Paper presents analysis of the decay rate (ba) estimation methodology based on respirometric assays measuring the oxygen uptake rate (OUR). Evaluation of this simple and cheap method was made based on decay estimation tests performed on sludge samples from side-stream partial nitritation reactor treating reject water from digested sludge dewatering. Database obtained from these tests were analyzed to evaluate the impact of respirometric assay duration on calculated decay rate values. 11 time ranges were selected for the performed analysis. Calculated ba values were compared showing the optimal test duration between 5–6 hours, while test shorter than 2 hours resulted in unsatisfactory ba outcome.

Phenomenology of doublet-triplet fermionic dark matter in nonstandard cosmology and multicomponent dark sectors

We consider the doublet-triplet fermionic model in the scheme of the custodial limit when the dark matter (DM) candidate is pure doublet and lies at the electroweak scale. This scheme, despite being an appealing and promising DM model, is severely constrained by the interplay between the DM relic density constraint and the LHC measurement of the Higgs diphoton decay rate. In this work, the DM relic density is considered to arise from either a nonstandard cosmology scenario or as a part of a larger sector encompassing other DM particles, this in order to saturate the observed relic abundance. For these scenarios we investigate the impact of the new sector in different collider observables, and study constraints coming from direct detection and indirect detection of gamma-rays both in the diffuse and linelike spectrum. As a result, we find that in the nonstandard cosmology scenario most experiments impose, up to a certain point, restrictions, though large portions of the parameter space are still viable. For the multicomponent case, only direct detection imposes constraints.

Musical drumhead damping using externally applied commercial products

Snare drums and tom toms used in drum sets often produce an undesirable high frequency ringing sound when struck. Drummers have historically applied DIY damping solutions to address this ringing, placing objects such as wallets and tape on the heads. A large variety of inexpensive commercial products is now available to dampen drums in a more controlled manner. The most commonly used products consist of small adhesive pads that can be placed directly on the drumhead at desired locations, either singly or in combinations. An experimental investigation of the ringing drumhead modes and the effects of the damping pads is reported. Decay rate measurements indicate that the (3,1), (4,1), and (5,1) modes often contribute the most to the ringing sound, and that these modes are strongly affected by the damping pads. Another class of commercial dampener consists of thin annular rings of Mylar that conform to the perimeter of the drum head. These free-floating rings produce a similar damping effect, but dissipate e...

Neutrino mass from Higgs quadruplet and multicharged Higgs searches at the LHC

In this paper, we revisit the dimension-7 neutrino mass generation mechanism based on the addition of an isospin $3/2$ scalar quadruplet and two vector-like iso-triplet leptons to the standard model. We discuss the LHC phenomenology of the charged scalars of this model, complemented by the electroweak precision and lepton flavor violation constraints. We pay particular attention to the triply charged and doubly charged components. We focus on the same-sign-tri-lepton signatures originating from the triply-charged scalars and find a discovery reach of 600 - 950 GeV at 3 ab$^{-1}$ of integrated luminosity at the LHC. On the other hand, doubly charged Higgs has been an object of collider searches for a long time, and we show how the present bounds on its mass depend on the particle spectrum of the theory. Strong constraint on the model parameter space can arise from the measured decay rate of the Standard Model Higgs to a pair of photons as well.

Spectral investigations of Sm3+/Yb3+: TeO2 + ZnO + Nb2O5 +TiO2 glasses for the conversion of Si -based solar cell applications

Sm3+ singly and Sm3+/Yb3+ co-doped tellurite glasses have been prepared by melt quenching technique. The prepared glasses are characterized through optical absorption, excitation, fluorescence and decay rate measurements. Judd-Ofelt theory has been employed to find the radiative properties and also stimulated emission cross-sections by using Futchbauer-Ladenbergh formula. The energy transfer mechanism from Sm3+ to Yb3+ ion has been analyzed. The theoretical energy transfer efficiency and quantum efficiency values were calculated from the decay curves of the Sm3+/Yb3+ co-doped tellurite glasses. The results indicate that the prepared glasses can be used as visible to near-infrared converting material to improve the conversion efficiency of silicon solar cells.

Non-Bloch decay of Rabi oscillations in liquid state NMR

Rabi oscillations are known to exhibit non-Bloch behaviour in anisotropic media. In this letter, we report an experimental observation of non-Bloch decay of Rabi oscillations in isotropic liquid state NMR. To avoid the dephasing due to the radio-frequency inhomogeneities, we develop a modified version of the rotary echo protocol and use it to determine the decay rates of Rabi oscillations. We find that the measured decay rates are proportional to the square of the Rabi frequencies and the proportionality constant is of the order of tens of picoseconds. Further, we show that this non-Bloch nature of the decay rates becomes less prominent with increasing temperature. The implications of the presence of non-Bloch decay rates in liquid state NMR in the context of ensemble quantum computing are also discussed.

Near-infrared in situ generation of the higher-energy trans conformer of tribromoacetic acid: Observation of a large-scale matrix-site changing mediated by conformational conversion.

The first observation of the higher-energy conformer of tribromoacetic acid (trans-TBAA) is reported. The conformer was produced in cryogenic matrices (Ar, Kr, and N2) by in situ selective narrowband near-infrared excitation of the lower-energy cis-TBAA conformer and characterized both structurally and vibrationally. The novel trans-TBAA conformer is shown to spontaneously decay to the most stable cis-TBAA form in all studied matrix media, by tunneling, and the measured decay rates in the different matrices were compared with those of the trans conformers of other carboxylic acids in similar experimental conditions. In the N2 matrix, where trans-TBAA establishes a specific stabilizing intermolecular interaction with the host N2 molecules via its OH group and is about 11 times more stable than in rare gas matrices, the effect of changing the irradiation wavenumber within the 2νOH absorption profile was investigated in detail. An interesting phenomenon of matrix-site changing mediated by conformational conversion was observed in the N2 matrix: vibrational excitation of cis-TBAA in the 2νOH wavenumber range predominantly converts the molecules located in a specific "matrix site" into trans-TBAA; then, relaxation (by tunneling) of the produced higher-energy conformer back to the cis form populates almost exclusively another "matrix site." The experimental studies received support from quantum chemistry calculations, which allowed a detailed characterization of the relevant regions of the potential energy surface of the molecule and the detailed assignment of the infrared spectra of the two conformers in the various matrices.

Optical spectroscopy of Dy3+ doped Na2O-MgO-Bi2O3-SiO2 glasses for luminescence applications

The aim of the present work is to study the optical and luminescence properties of Dy2O3 doped Na2O-MgO-Bi2O3-SiO2 glasses. The Dy3+ ion is chosen as dopant because it emits three visible bands, blue (470–485 nm; 4F9/2→6H15/2), yellow (570–580 nm; 4F9/2→6H13/2) and red (640–655 nm; 4F9/2→6H11/2) luminescence and finds its applications in the fields of laser, white LEDs, telecommunication technology and display devices. NaMgBiSiDy glasses with the compositions of (30-x)SiO2: 10Bi2O3: 30Na2O: 30MgO: xDy2O3 where x=0.0, 0.1, 0.5, 1.0, 1.5 and 2.0 mol% were prepared by melt-quenching technique and characterized by using density, optical absorption photoluminescence (PL) and decay rate measurements as function of different concentrations. The chromaticity coordinates were calculated from emission spectra and analyzed with CIE color diagram and appear in the white light region under ultraviolet excitation.

The NEXT high pressure xenon gas TPC for neutrinoless double beta decay searches

A high pressure xenon gas time projection chamber with electroluminescent amplification (EL HPGXe TPC) offers for the search of the neutrinoless double beta decay (0νββ): an excellent energy resolution (0.5−0.7% FWHM at the Qββ) and tracking capabilities as demonstrated by the NEXT collaboration using two kg-scale prototypes. The NEXT collaboration is constructing an EL HPGXe TPC capable to hold 100 kg (NEXT-100) of xenon isotopically enriched in 136Xe. Since October 2016, a first phase of the NEXT experiment, called NEW detector, is running with depleted 136Xe at the Laboratorio Subterraneo de Canfranc. The NEW detector is a scale 1:2 in size of the NEXT-100 detector and uses same materials and photosensors. It will be used to perform a characterization of the 0νββ backgrounds and a measurement of the standard double beta decay rate. Recent results on the characterization of the NEW detector performance using data from calibration sources are presented.