Decay Half-lives Research Articles

Examination of α-decay half-lives of undetected transfermium isotopes

This study reports the [Formula: see text]-decay half-lives of 39 transfermium isotopes with [Formula: see text], most of which have not been observed. The half-lives were calculated using micro–macroscopic approaches and semi-empirical formulae, applying current [Formula: see text]-decay Q-values from the latest mass database, AME2016. These results were compared to predicted values in previous works to evaluate the efficiency of and difference between various calculation methods. We found that the [Formula: see text]-resonance approach used in a previous study is not appropriate to predict though most other approaches are mutually consistent. An uncertainty of 70% was observed in the present theoretical calculations, similar to that observed in measurements. A Q-value uncertainty of 10% can lead to a large variation of 3 orders of magnitude in predicted [Formula: see text]-decay half-life. We also found that the dominance of either [Formula: see text] decay or spontaneous fission is unclear for the isotopes with [Formula: see text]–[Formula: see text], whereas most of the nuclei of [Formula: see text]–[Formula: see text] can be clearly identified as [Formula: see text] emitters. Finally, we provide the updated [Formula: see text]-decay half-lives for the isotopes of interest, including their uncertainties and corresponding decay modes.

Cluster radioactivity of superheavy nuclei 290–310120 using different proximity functions

The present work used eight different proximity functions in the modified liquid drop model [MGLDM] to study the cluster and alpha decay half-lives in the superheavy nuclei Z = 120. The values produced by the present work are compared with experiments. We have explored the proximity function is suitable in MGLDM for the cluster and alpha radioactivity of superheavy nuclei. The present work is useful in the study of decay modes of superheavy nuclei Z = 120.

Treatment of carbon monoxide poisoning: high-flow nasal cannula versus non-rebreather face mask

Objective In this study, the aim was to compare the rate of decrease in carboxyhemoglobin (COHb) values at consecutive time points and calculate the half-life of COHb (COHb t½) in patients admitted to the emergency department (ED) with carbon monoxide (CO) poisoning and treated with either high flow nasal cannula oxygen therapy (HFNC) or non-rebreather face mask (NRFM). Methods This retrospective, cohort study with historical controls was performed over a 2-year period and included adult patients with CO poisoning, whose COHb values were checked. The HFNC group consisted of patients admitted to the ED with CO poisoning when HFNC was available in the hospital, while the NRFM group consisted of patients who presented to the ED with CO poisoning before the availability of HFNC. The primary outcome of the study was to detect the COHb t½. Results A total of 71 patients were enrolled in the study. While 35 patients received oxygen with NRFM, 36 patients received HFNC. The mean COHb t½ in the HFNC group was 41.1 min (95% CI: 31.0–58.4) and 64.0 min (95% CI: 43.5–114.4) in the NRFM group. We did not find a significant difference in the COHb t½ between the HFNC group and NRFM group (p = 0.099). COHb levels between treatment arms at serial time points showed a statistically significant difference at 60 min (p = 0.048). We compared the decay constant and half-life of COHb between groups according to gender. In both genders, COHb t½ was significantly different between groups, and COHb t½ was lower in the patients treated with HFNC. Conclusion HFNC was effective in reducing the half-life of COHb values in patients with carbon monoxide poisoning. Prospective studies to be conducted in larger groups are needed to fully understand the effect of HFNC on carbon monoxide poisoning.

Exploring the α-decay chain of 302122 within relativistic mean-field formalism

The ground and first excited state structural properties, like binding energy, charge radius, deformation parameter, pairing energy, and two-neutron separation energy, for the isotopic chain of Z = 122 are analysed. The axially deformed relativistic mean-field formalism with NL3* force parameter is used for the present analysis. Based on the analysis of binding energy per particle, chemical potential, and single-particle spacing, we predict the isotopes of Z = 122 with N = 180, 182, and 184 are the possible stable nuclei over the considered isotopic chain. The α-decay energies and the decay half-lives of 302122 chains are investigated using four different empirical formulae. The results of our calculations are compared with the available experimental data and finite range droplet model predictions. We also established a correlation for the decay energy with the half-lives for the considered α-decay chains for various empirical formulae.

Study of decay modes in transfermium isotopes

In the unknown territory of transfermium nuclei, the relativistic mean-field (RMF) theory has been applied to probe decay modes which include α-decay, spontaneous fission (SF), and a less explored weak-decay. These decay modes are analyzed on equal footing for 101≤Z≤109 and as a consequence, the half-lives for weak-decay are indeed found comparable for several isotopes. Our prediction of decay modes and half-lives are found in excellent agreement with available experimental decay modes and half-lives along with the results of some other theories. Out of α, β+/EC, β−, and SF, the most probable decay mode is anticipated along with its half-life over a wide range of odd and even nuclei to frame a novel sight into terra incognita.

Investigation of ASIC-based signal readout electronics for LEGEND-1000

LEGEND, the Large Enriched Germanium Experiment for Neutrinoless ββ Decay, is a ton-scale experimental program to search for neutrinoless double beta (0νββ) decay in the isotope 76Ge with an unprecedented sensitivity. Building on the success of the low-background 76Ge-based GERDA and \ extsc{Majorana Demonstrator} experiments, the LEGEND collaboration is targeting a signal discovery sensitivity beyond 1028 yr on the decay half-life with approximately 10 t⋅yr of exposure. Signal readout electronics in close proximity to the detectors plays a major role in maximizing the experiment's discovery sensitivity by reducing electronic noise and improving pulse shape analysis capabilities for the rejection of backgrounds. However, the proximity also poses unique challenges for the radiopurity of the electronics. Application-specific integrated circuit (ASIC) technology allows the implementation of the entire charge sensitive amplifier (CSA) into a single low-mass chip while improving the electronic noise and reducing the power consumption. In this work, we investigated the properties and electronic performance of a commercially available ASIC CSA, the XGLab CUBE preamplifier, together with a p-type point contact high-purity germanium detector. We show that low noise levels and excellent energy resolutions can be obtained with this readout. Moreover, we demonstrate the viability of pulse shape discrimination techniques for reducing background events.

Analysis of β+ decay of 13N nucleus using a modified one-particle approach

It is known that the calculated values of log(ft) and the half-life of beta decay are less than the measured values when a single-particle approach is used to calculate these quantities. In this article, we discuss the importance of taking into account the spectroscopic factor in the calculation of the half-life and log(ft) beta decay of nuclei containing one nucleon in the outermost shell. We also emphasize the dominant role of the asymptotic normalization coefficient, which takes into account the many-particle effect and allows us to obtain the spectroscopic factor necessary to describe the reaction 13N → 13C + β+ + νe . We find the asymptotic normalization coefficients using the experimental data of the elastic scattering phase-shift of the proton and neutron on 12C. Using overlap functions instead of single-particle functions, we obtain a better comparison with the experimental data. The overlap function is represented as the product of the single-particle function and the root of the corresponding spectroscopic factor.

Study of the dependence of alpha decay half-life on the surface symmetry energy

In this study, the effect of the surface symmetry energy on the neutron skin thickness and division of it into the bulk and surface parts are investigated by determination of the symmetry energy coefficient [Formula: see text] of finite nuclei. We demonstrate the importance of the isospin asymmetry distribution in the symmetry energy coefficient of finite nuclei at the surface region. We attempt to find out how different surface symmetry energies may affect alpha decay half-life. The Skyrme interactions are used to describe the neutron and proton density distributions and to calculate the symmetry energy coefficient [Formula: see text] of four nuclei and the surface symmetry energy. The chosen Skyrme interactions can produce the binding energy and root-mean-square charge radii of both mother and daughter nuclei. We single out the spherical isotones of [Formula: see text] named [Formula: see text]Pb, [Formula: see text]Po, [Formula: see text]Rn and [Formula: see text]Ra for daughter nuclei and explore the dependence of the bulk and surface contributions on the surface symmetry energy. The half-life of mother nuclei, i.e., [Formula: see text]Po, [Formula: see text]Rn, [Formula: see text]Ra and [Formula: see text]Th, is employed to investigate the extent to which it is affected by different surface symmetry energies. The calculated half-lives show a downward tendency for different surface symmetry energies which can be caused by various neutron skin thicknesses.

Search for second order response of nuclei to isospin probes and their connection to double beta decay

In order to get quantitative information on neutrino absolute mass scale from the possible measurement of the 0νββ decay half-lives, the knowledge of the Nuclear Matrix Elements (NME) involved in such transitions is mandatory. NMEs are not observables and can only be accessed by theory. However, the many-body nature of the nuclear state involved in the decay, makes this task possible only at approximate level. In this perspective, several experimental approaches have been proposed in the years in order to provide useful information to better constrain the theory. Here a short overview of the role of charge exchange reactions in this scenario is given, with particular emphasis on second order processes, known as Double Charge Exchange (DCE) reactions.

Recent results on heavy-ion direct reactions of interest for 0νββ decay at INFN - LNS

Neutrinoless double beta decay of nuclei, if observed, would have important implications on fundamental physics. In particular it would give access to the effective neutrino mass. In order to extract such information from 0νββ decay half-life measurements, the knowledge of the Nuclear Matrix Elements (NME) is of utmost importance. In this context the NUMEN and the NURE projects aim to extract information on the NME by measuring cross sections of Double Charge Exchange reactions in selected systems which are expected to spontaneously decay via 0νββ. In this work an overview of the experimental challenges that NUMEN is facing in order to perform the experiments with accelerated beams and the research and development activity for the planned upgrade of the INFN-LNS facilities is reported.

Calculations of the α-decay properties of Z = 120, 122, 124, 126 isotopes * * Supported by the National Natural Science Foundation of China (11635003, 11025524, 11161130520), the National Basic Research Program of China (2010CB832903), the European Commission’ s 7th Framework Programme (Fp7-PEOPLE-2010-IRSES) under Grant Agreement Project (269131), the General Financial Grant from the China Postdoctoral Science Foundation (2017M620672), BeiJing

The α-decay properties of even-Z nuclei with Z = 120, 122, 124, 126 are predicted. We employ the generalized liquid drop model (GLDM), Royer's formula, and universal decay law (UDL) to calculate the -decay half-lives. By comparing the theoretical calculations with the experimental data of known nuclei from Fl to Og, we confirm that all the employed methods can reproduce the -decay half-lives well. The preformation factor and -decay energy show that 120, 122, and 124 might be stable. The -decay half-lives show a peak at Z = 120, N = 184, and the peak vanishes when Z = 122, 124, 126. Based on detailed analysis of the competition between -decay and spontaneous fission, we predict that nuclei nearby N = 184 undergo -decay. The decay modes of 120, 122, 124, and 126 are also presented.

Sequences of single-particle energy levels of even–even SHN with Z = 116−132 based on α-decay systematics

The [Formula: see text]-decay half-lives, [Formula: see text], for five heavy and nine superheavy even–even nuclei with [Formula: see text] and [Formula: see text], respectively, have been calculated within the density-dependent cluster model. The [Formula: see text]-nucleus potential was derived by employing the double-folding model with a realistic [Formula: see text] interaction whose exchange part has a finite-range. We considered several isotopes for each [Formula: see text]-value. The behavior of [Formula: see text] against the neutron number variation for different isotopes of each element is investigated. We found a clear similarity in the behavior of [Formula: see text] for the isotopes of a number of successive elements. The proton pair in the emitted [Formula: see text] particle, for these elements, comes from the same proton energy level. Also, the behavior of [Formula: see text] with the parent neutron number, for different isotopes of an element, was found to be governed by the existence of neutron magic number or neutron-level closure. The possibility to correlate the behavior of [Formula: see text] for several isotopes of a specific element with the proton and neutron energy levels of this element is investigated. Moreover, the behavior of [Formula: see text] when adding successive proton pairs to fill the energy level at different neutron numbers is studied. This work can be considered as a significant step forward to correlate the behavior of [Formula: see text] with the energy levels.

Theoretical Study of Proton Radioactivity

The unified fission model with a Modified-Woods–Saxon (MWS) nuclear potential is used to study the proton decay of spherical proton emitters from the ground and isomeric states in the framework of WKB approximation. The results of our calculations are compared to those obtained by other theoretical models as well as experimental data. It is shown that the unified fission model with the MWS nuclear potential can be successfully used to evaluate the proton decay half-lives.

Systematic study of the α decay preformation factors of the nuclei around the Z = 82, N = 126 shell closures within the generalized liquid drop model * * Supported in part by the National Natural Science Foundation of China (11205083, 11505100, 11705055), the Construct Program of the Key Discipline in Hunan Province, the Research Foundation of Education Bureau of

In this study, we systematically investigate the decay preformation factors, , and the decay half-lives of 152 nuclei around Z = 82, N = 126 closed shells based on the generalized liquid drop model (GLDM) with being extracted from the ratio of the calculated decay half-life to the experimental one. The results show that there is a remarkable linear relationship between and the product of valance protons (holes) and valance neutrons (holes) . At the same time, we extract the decay preformation factor values of the even–even nuclei around the Z = 82, N = 126 closed shells from the study of Sun [J. Phys. G: Nucl. Part. Phys., 45: 075106 (2018)], in which the decay was calculated by two different microscopic formulas. We find that the decay preformation factors are also related to . Combining with our previous studies [Sun , Phys. Rev. C, 94: 024338 (2016); Deng , ibid. 96: 024318 (2017); Deng , ibid. 97: 044322 (2018)] and that of Seif [Phys. Rev. C, 84: 064608 (2011)], we suspect that this phenomenon of linear relationship for the nuclei around the above closed shells is model-independent. This may be caused by the effect of the valence protons (holes) and valence neutrons (holes) around the shell closures. Finally, using the formula obtained by fitting the decay preformation factor data calculated by the GLDM, we calculate the decay half-lives of these nuclei. The calculated results agree with the experimental data well.

Study of Fuel-Smoke Dynamics in a Prescribed Fire of Boreal Black Spruce Forest through Field-Deployable Micro Sensor Systems

Understanding the combustion dynamics of fuels, and the generation and propagation of smoke in a wildland fire, can inform short-range and long-range pollutant transport models, and help address and mitigate air quality concerns in communities. Smoldering smoke can cause health issues in nearby valley bottoms, and can create hazardous road conditions due to low-visibility. We studied near-field smoke dynamics in a prescribed fire of 3.4 hectares of land in a boreal black spruce forest in central Alberta. Smoke generated from the fire was monitored through a network of five field-deployable micro sensor systems. Sensors were placed within 500–1000 m of the fire area at various angles in downwind. Smoke generated from flaming and smoldering combustions showed distinct characteristics. The propagation rates of flaming and smoldering smoke, based on the fine particulate (PM2.5) component, were 0.8 and 0.2 m/s, respectively. The flaming smoke was characterized by sharp rise of PM2.5 in air with concentrations of up to 940 µg/m3, followed by an exponential decay with a half-life of ~10 min. Smoldering combustion related smoke contributed to PM2.5 concentrations above 1000 µg/m3 with slower decay half-life of ~18 min. PM2.5 emissions from the burn area during flaming and smoldering phases, integrated over the combustion duration of 2.5 h, were ~15 and ~16 kilograms, respectively, as estimated by our mass balance model.

Subtherapeutic Acetazolamide Doses as a Noninvasive Method for Assessing Medication Adherence.

Adherence monitoring is a vital component of clinical efficacy trials, as the regularity of medication consumption affects both efficacy and adverse effect profiles. Pill-counts do not confirm consumption, and invasive plasma assessments can only assist post hoc assessments. We previously reported on the pharmacokinetics of a potential adherence marker to noninvasively monitor dosage consumption during a trial without breaking a blind. We reported that consumption cessation of subtherapeutic 15mg acetazolamide (ACZ) doses showed a predictable urinary excretion decay that was quantifiable for an extended period. The current study describes the clinical implementation of 15mg ACZ doses as an adherence marker excipient in distinct cohorts taking ACZ for different "adherence" durations. We confirm that ACZ output did not change (accumulate) during 18-20days of adherence, and developed and assessed urinary cutoffs as nonadherence indicators. We demonstrate that whereas an absolute concentration cutoff (989ng/mL) lacked sensitivity, a creatinine normalized equivalent (1,376ng/mg ACZ) was highly accurate at detecting nonadherence. We also demonstrate that during nonadherent phases of three trials, creatinine-normalized urinary ACZ elimination was reproducible within and across trials with low variability. Excretion was first order, with a decay half-life averaging ~2.0days. Further, excretion remained quantifiable for 14days, providing a long period during which the date of last consumption might be determined. We conclude that inclusion of 15mg ACZ as a dosage form adherence marker excipient, provides a reliable and sensitive mechanism to confirm medication consumption and detect nonadherence during clinical efficacy trials.

Clusters decay half-live of various heavy deformed nuclei with mass numbers in the range 221 ≤ A ≤ 242

Decay half-live of several clusters between 14C and 34Si emitted from various heavy deformed nuclei with mass numbers in the range 221 ≤ A ≤ 242 are calculated using nuclear Woods-Saxon (VN(r, θ)), Coulomb (VC(r, θ)) and rotational (Vl(r)) potentials considering deformation for both daughter and cluster and spherical configuration for them. Half-live of these decays are also obtained using a semi-empirical formula. Obtained results considering deformation are compared with the half-live of spherical configuration, results of a semi-empirical formula as well as the available experimental data. The comparison indicates that the calculated half-lives considering deformation are better agreed with the experimental data than the results of spherical configuration and the out put of semi-empirical formula. Also, The obtained results using deformation is better confirmed the Geiger-Nuttall low of alpha decay, especially for emission of light clusters as expected.

A systematic study of α-decay in superheavy nuclei using a Hartree-Fock-Bogoliubov model

Predictions on the alpha decay and spontaneous fission of the superheavy nuclei in the range of Z = 106–118 have been systematically done within the Hartree-Fock-Bogoliubov model and different Skyrme type interactions. A comparison of the results of the current study with experimental values showed good agreement. This study was extended to unknown isotopes in the range of Z = 116–118. The calculated alpha decay half-lives are in the range of 10−5 to 102 s which lie within measurable values. To identify the long-lived isotopes in the mass region, spontaneous fission half-lives were performed using a semi-empirical formula. The results revealed that the isotopes 276,275,274,272,268110, 276,275,273111, 282,280,279112, 281,280,279113, 284,283114, 286115, 289116, 296,295,292,291117, 297,296118, and 295,293,292118 survived fission and had alpha decay mode as the predominant mode of decay which could be synthesized in the laboratory.

Calculation of Q-value and half-life of alpha decay in super heavy elements using S-matrix theory

The half-life and the [Formula: see text]-value of alpha decay in several super heavy elements are calculated. The nuclear potential is computed using the double-folding method. Using the S-matrix theory, the alpha decay is treated as a scattering problem between alpha particle and the daughter nucleus. Nuclear potential was approximated by the parameterized Woods–Saxon potential. This idea has also been extended to predict the half-life and the [Formula: see text]-value of the heaviest elements of few other alpha chains.

A new formalism for the study of the surface tension coefficient of α-nuclei systems using the density-dependent nucleon-nucleon interactions

This study investigates the nuclear surface tension coefficient, γ, of the proximity formalism by using the microscopic double-folding (DF) model with the realistic density-dependent (DD) nucleon-nucleon interaction of the effective M3Y forces type (including DDM3Y1, CDM3Y4 and BDM3Y1) for the ground-state to ground-state α transition of 230 parent nuclei with Z = 61-99. In fact, the present work can be considered as an expansion of the previous study which has been performed by Gharaei and Mohammadi using CDM3Y6 version in 2019. Within the propsed approach, we have tried to present a new approach for the calculation of the surface energy coefficient, γ, in alpha-decay by integrating the proximity and DF potential models. In addition, we present a new dependency of the surface energy coefficient, γ, on the asymmetry parameter, , of the considered α-nuclei systems by fitting all of the calculated values. The obtained results suggest a new formalism for the coefficient γ that is dependent directly on the selection of the interaction type. We also test the validity of the suggested formula. To this aim, by using the the obtained formula of the coefficient γ in the original version of the proximity potentials, we calculate the theoretical values of the alpha-decay half-lives for different nuclei in the framework of the WKB approximation. The calculated results are compared with the corresponding experimental data and those obtained from the original proximity potential 1977. It is shown that the modified forms of the proximity potential model, labeled as Prox. New (DDM3Y1), Prox. New (CDM3Y4) and Prox. New (BDM3Y1), provide better descriptions of the experimental α-decay half-lives than the proximity potential 1977 (Prox. 77). Further, the best results are obtained using the Prox. New (CDM3Y4) potential model for our selected mass range. Using the modified forms of the proximity potential, we examined the closed-shell effects in nuclei and the validity of the Geiger-Nuttall law. Additionally, the results of the Prox. New (CDM3Y4) potential model are compared with the various empirical formulas for alpha decay half-lives. Ultimately, the prediction of alpha decay half lives is made for superheavy nuclei with Z=117-120.