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1.
Phys Rev Lett ; 130(21): 212701, 2023 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-37295108

RESUMEN

The rate of the final step in the astrophysical αp process, the ^{34}Ar(α,p)^{37}K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the ^{34}Ar(α,p)^{37}K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the ^{34}Ar,Cl(α,p)^{37}K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The ^{34}Ar(α,2p)^{36}Ar cross section, which can be exclusively attributed to the ^{34}Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.


Asunto(s)
Helio , Hidrógeno , Modelos Estadísticos , Neutrones
2.
Phys Rev Lett ; 129(17): 172701, 2022 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-36332266

RESUMEN

The ß-delayed one- and two-neutron emission probabilities (P_{1n} and P_{2n}) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P_{1n} of ^{130,131}Ag, ^{133,134}Cd, ^{135,136}In, and ^{138,139}Sn were determined for the first time, and stringent upper limits were placed on P_{2n} for nearly all cases. ß-delayed two-neutron emission (ß2n) was unambiguously identified in ^{133}Cd and ^{135,136}In, and their P_{2n} were measured. Weak ß2n was also detected from ^{137,138}Sn. Our results highlight the effect of the N=82 and Z=50 shell closures on ß-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and γ emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P_{1n} and P_{2n} have a direct impact on the odd-even staggering of the final abundance, improving the agreement between calculated and observed Solar System abundances. The odd isotope fraction of Ba in r-process-enhanced (r-II) stars is also better reproduced using our new data.

3.
Phys Rev Lett ; 126(4): 042701, 2021 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-33576674

RESUMEN

Proton capture on the excited isomeric state of ^{26}Al strongly influences the abundance of ^{26}Mg ejected in explosive astronomical events and, as such, plays a critical role in determining the initial content of radiogenic ^{26}Al in presolar grains. This reaction also affects the temperature range for thermal equilibrium between the ground and isomeric levels. We present a novel technique, which exploits the isospin symmetry of the nuclear force, to address the long-standing challenge of determining proton-capture rates on excited nuclear levels. Such a technique has in-built tests that strongly support its veracity and, for the first time, we have experimentally constrained the strengths of resonances that dominate the astrophysical ^{26m}Al(p,γ)^{27}Si reaction. These constraints demonstrate that the rate is at least a factor ∼8 lower than previously expected, indicating an increase in the stellar production of ^{26}Mg and a possible need to reinvestigate sensitivity studies involving the thermal equilibration of ^{26}Al.

4.
Phys Rev Lett ; 125(26): 262701, 2020 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-33449748

RESUMEN

The interpretation of observations of cooling neutron star crusts in quasipersistent x-ray transients is affected by predictions of the strength of neutrino cooling via crust Urca processes. The strength of crust Urca neutrino cooling depends sensitively on the electron-capture and ß-decay ground-state-to-ground-state transition strengths of neutron-rich rare isotopes. Nuclei with a mass number of A=61 are predicted to be among the most abundant in accreted crusts, and the last remaining experimentally undetermined ground-state-to-ground-state transition strength was the ß decay of ^{61}V. This Letter reports the first experimental determination of this transition strength, a ground-state branching of 8.1_{-3.1}^{+4.0}%, corresponding to a log ft value of 5.5_{-0.2}^{+0.2}. This result was achieved through the measurement of the ß-delayed γ rays using the total absorption spectrometer SuN and the measurement of the ß-delayed neutron branch using the neutron long counter system NERO at the National Superconducting Cyclotron Laboratory at Michigan State University. This method helps to mitigate the impact of the pandemonium effect in extremely neutron-rich nuclei on experimental results. The result implies that A=61 nuclei do not provide the strongest cooling in accreted neutron star crusts as expected by some predictions, but that their cooling is still larger compared to most other mass numbers. Only nuclei with mass numbers 31, 33, and 55 are predicted to be cooling more strongly. However, the theoretical predictions for the transition strengths of these nuclei are not consistently accurate enough to draw conclusions on crust cooling. With the experimental approach developed in this work, all relevant transitions are within reach to be studied in the future.

5.
Rev Chil Pediatr ; 91(4): 597-604, 2020 Aug.
Artículo en Español | MEDLINE | ID: mdl-33399739

RESUMEN

It is increasingly common to provide medical care in the Intensive Care Unit (ICU) for immigrant children and adolescents as well as those born in Chile with parents in such condition. Currently, this has caused that the health team has to face diverse infrequent pathologies in our country and/ or diagnostic problems derive from the poor knowledge of genetic conditions of this population, some resulting from their health conditions. This review addresses several aspects of hematological, infectious, parasitic, respiratory, and cardiovascular pathologies, all relevant topics to know during their stay in the ICU. It is a duty of the health team to be updated on pathologies of low prevalence in our country, some of them very little known until a decade ago, but which are currently increasingly present in the ICUs of the Chilean public health system.


Asunto(s)
Enfermedades Cardiovasculares , Cuidados Críticos/métodos , Emigrantes e Inmigrantes , Enfermedades Hematológicas , Infecciones , Unidades de Cuidados Intensivos , Enfermedades Respiratorias , Adolescente , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/etnología , Enfermedades Cardiovasculares/terapia , Niño , Preescolar , Chile/epidemiología , Enfermedades Hematológicas/diagnóstico , Enfermedades Hematológicas/etnología , Enfermedades Hematológicas/terapia , Humanos , Lactante , Recién Nacido , Infecciones/diagnóstico , Infecciones/etnología , Infecciones/terapia , Prevalencia , Enfermedades Respiratorias/diagnóstico , Enfermedades Respiratorias/etnología , Enfermedades Respiratorias/terapia
6.
Phys Rev Lett ; 122(23): 232701, 2019 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-31298878

RESUMEN

The ^{23}Al(p,γ)^{24}Si reaction is among the most important reactions driving the energy generation in type-I x-ray bursts. However, the present reaction-rate uncertainty limits constraints on neutron star properties that can be achieved with burst model-observation comparisons. Here, we present a novel technique for constraining this important reaction by combining the GRETINA array with the neutron detector LENDA coupled to the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The ^{23}Al(d,n) reaction was used to populate the astrophysically important states in ^{24}Si. This enables a measurement in complete kinematics for extracting all relevant inputs necessary to calculate the reaction rate. For the first time, a predicted close-lying doublet of a 2_{2}^{+} and (4_{1}^{+},0_{2}^{+}) state in ^{24}Si was disentangled, finally resolving conflicting results from two previous measurements. Moreover, it was possible to extract spectroscopic factors using GRETINA and LENDA simultaneously. This new technique may be used to constrain other important reaction rates for various astrophysical scenarios.

7.
Bull Entomol Res ; 109(6): 812-820, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30968782

RESUMEN

Tuta absoluta (Meyrick), a key pest of tomato, is quickly spreading over the world and biological control is considered as one of the control options. Worldwide more than 160 species of natural enemies are associated with this pest, and an important challenge is to quickly find an effective biocontrol agent from this pool of candidate species. Evaluation criteria for control agents are presented, with the advantages they offer for separating potentially useful natural enemies from less promising ones. Next, an aggregate parameter for ranking agents is proposed: the pest kill rate km. We explain why the predator's intrinsic rate of increase cannot be used for comparing the control potential of predators or parasitoids, while km can be used to compare both types of natural enemies. As an example, kill rates for males, females and both sexes combined of three Neotropical mirid species (Campyloneuropsis infumatus (Carvalho), Engytatus varians (Distant) and Macrolophus basicornis (Stål)) were determined, taking all life-history data (developmental times, survival rates, total nymphal and adult predation, sex ratios and adult lifespan) into account. Based on the value for the intrinsic rate of increase (rm) for T. absoluta and for the kill rate km of the predators, we predict that all three predators are potentially able to control the pest, because their km values are all higher than the rm of the pest. Using only km values, we conclude that E. varians is the best candidate for control of T. absoluta on tomato, with C. infumatus ranking second and M. basicornis last.


Asunto(s)
Agentes de Control Biológico/clasificación , Mariposas Nocturnas , Conducta Predatoria , Animales , Femenino , Heterópteros/fisiología , Estadios del Ciclo de Vida , Solanum lycopersicum/parasitología , Masculino , Control Biológico de Vectores/métodos
8.
Rev Chil Pediatr ; 88(5): 668-676, 2017.
Artículo en Español | MEDLINE | ID: mdl-29546955

RESUMEN

Down syndrome is the most common chromosomal abnormality in newborns, with a high incidence in Chile. This condition presents unique physiological aspects that should be known, which can affect the child during their stay in an Intensive Care Unit, beyond the neonatal period This review is focused on the respiratory, cardiovascular, infectious and neurological disorders. Anesthetic management and postoperative analgesia considerations, weaning from mechanical ventilation, cervical spine instability and prognosis of the critically ill child with Down syndrome are also analyzed. The evaluation of these conditions should be performed when the patient is admitted to the intensive care unit. The purpose of this update is to update the knowledge of the diagnosis and treatment of potential complications of children with Down syndrome during their stay in the unit of critical patient.


Asunto(s)
Cuidados Críticos/métodos , Síndrome de Down/complicaciones , Niño , Enfermedad Crítica , Síndrome de Down/fisiopatología , Humanos , Unidades de Cuidados Intensivos , Atención Perioperativa/métodos
9.
Phys Rev Lett ; 117(1): 012501, 2016 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-27419564

RESUMEN

The ß-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with ß-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N≳126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the ß-decay strength distribution. This provides important constraints on global theoretical models currently used in r-process nucleosynthesis.

10.
Epidemiol Infect ; 144(12): 2621-32, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27165946

RESUMEN

Epidemiologists agree that there is a prevailing seasonality in the presentation of epidemic waves of respiratory syncytial virus (RSV) infections and influenza. The aim of this study is to quantify the potential relationship between the activity of RSV, with respect to the influenza virus, in order to use the RSV seasonal curve as a predictor of the evolution of an influenza virus epidemic wave. Two statistical tools, logistic regression and time series, are used for predicting the evolution of influenza. Both logistic models and time series of influenza consider RSV information from previous weeks. Data consist of influenza and confirmed RSV cases reported in Comunitat Valenciana (Spain) during the period from week 40 (2010) to week 8 (2014). Binomial logistic regression models used to predict the two states of influenza wave, basal or peak, result in a rate of correct classification higher than 92% with the validation set. When a finer three-states categorization is established, basal, increasing peak and decreasing peak, the multinomial logistic model performs well in 88% of cases of the validation set. The ARMAX model fits well for influenza waves and shows good performance for short-term forecasts up to 3 weeks. The seasonal evolution of influenza virus can be predicted a minimum of 4 weeks in advance using logistic models based on RSV. It would be necessary to study more inter-pandemic seasons to establish a stronger relationship between the epidemic waves of both viruses.


Asunto(s)
Epidemias , Gripe Humana/epidemiología , Orthomyxoviridae/fisiología , Infecciones por Virus Sincitial Respiratorio/epidemiología , Virus Sincitial Respiratorio Humano/fisiología , Estaciones del Año , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Gripe Humana/virología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Infecciones por Virus Sincitial Respiratorio/virología , España/epidemiología , Factores de Tiempo , Adulto Joven
11.
Rev Med Chil ; 144(6): 758-66, 2016 Jun.
Artículo en Español | MEDLINE | ID: mdl-27598496

RESUMEN

BACKGROUND: Oral cancer is a public health problem. Its world incidence in 2012, was 4.0 new cases per 100,000 inhabitants. AIM: To review the published literature on oral cancer in Chile. MATERIAL AND METHODS: Narrative review of the literature using databases such as Pubmed, Scielo and Google Scholar. The Key words oral cancer in Chile, Oral Cancer, Oral Cancer AND Chile were used. A critical appraisal the articles was carried out. RESULTS: Of 27 eligible studies, 11 studies were included and data from population registries were used. Oral and Oropharyngeal cancer mortality is 1% and morbidity corresponds to 1.6% of all cancers in Chile. By 2010 according to different authors, the male: female ratio ranges from 1.3: 1 to 1.4: 1 and the five years survival, from 46% to 56.9%. The main risk factors are smoking and alcohol use. CONCLUSIONS: The number of articles published in Chile about oral cancer is low.


Asunto(s)
Neoplasias de la Boca/mortalidad , Chile/epidemiología , Supervivencia sin Enfermedad , Femenino , Humanos , Incidencia , Masculino , Factores de Riesgo
12.
Phys Rev Lett ; 115(16): 162501, 2015 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-26550869

RESUMEN

We present the mass excesses of (52-57)Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85(59)((-54)(+0)) MeV and -21.0(1.3) MeV, respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A = 56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A≈56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.

13.
Phys Rev Lett ; 114(2): 022501, 2015 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-25635542

RESUMEN

We present results from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. We report the first mass measurements of ^{48}Ar and ^{49}Ar and find atomic mass excesses of -22.28(31) MeV and -17.8(1.1) MeV, respectively. These masses provide strong evidence for the closed shell nature of neutron number N=28 in argon, which is therefore the lowest even-Z element exhibiting the N=28 closed shell. The resulting trend in binding-energy differences, which probes the strength of the N=28 shell, compares favorably with shell-model calculations in the sd-pf shell using SDPF-U and SDPF-MU Hamiltonians.

14.
Phys Rev Lett ; 113(3): 032502, 2014 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-25083636

RESUMEN

An approach is presented to experimentally constrain previously unreachable (p, γ) reaction rates on nuclei far from stability in the astrophysical rp process. Energies of all critical resonances in the (57)Cu(p,γ)(58)Zn reaction are deduced by populating states in (58)Zn with a (d, n) reaction in inverse kinematics at 75 MeV/u, and detecting γ-ray-recoil coincidences with the state-of-the-art γ-ray tracking array GRETINA and the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The results reduce the uncertainty in the (57)Cu(p,γ) reaction rate by several orders of magnitude. The effective lifetime of (56)Ni, an important waiting point in the rp process in x-ray bursts, can now be determined entirely from experimentally constrained reaction rates.

15.
Rev Chil Pediatr ; 85(3): 378-87, 2014 Jun.
Artículo en Español | MEDLINE | ID: mdl-25697256

RESUMEN

Apparent life threatening events are defined as an acute episode in which the observer fears an infant < 1 year may die. ALTE is characterized by some combination of apnea, color or muscle tone change, chocking and has to be followed by cardiorespiratory reanimation. The present consensus paper reviews international and national evidence concerning diagnosis, etiologies, hospitalization criteria and indications for home monitoring.


Asunto(s)
Obstrucción de las Vías Aéreas/terapia , Apnea/terapia , Urgencias Médicas , Enfermedad Aguda , Reanimación Cardiopulmonar/métodos , Hospitalización , Humanos , Lactante
16.
Sci Total Environ ; 933: 172932, 2024 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-38703860

RESUMEN

Biodiversity is essential for the functioning of ecosystems and the provision of services. In recent years, the role of plantations in mitigating climate change through carbon sequestration has been highlighted. In the Mediterranean area, high-density poplar plantations in short-rotation with resprouting management (SRC) have been established for biomass purposes on mostly irrigated agricultural land, coexisting with rainfed and irrigated agricultural crops. This study aims to assess the contribution of these plantations to this type of agroforest ecosystem in terms of biodiversity. For this purpose, both flora and fauna diversity were evaluated both within and outside of the plantation. Additionally, the accumulated carbon in the biomass, as well as in the accompanying vegetation within the plantation, was assessed. Different indices were used to evaluate both the intrinsic diversity of the forest plantation and the degree of substitution and complementarity between the different communities of the landscape. Our findings reveal distinct biodiversity patterns in the land-use scenarios sampled. Specifically, we observed significantly higher flora-species richness in SRC plantations than in the adjacent agricultural land, whereas fauna richness showed a similar but slightly higher level in the forested area. A moderate level of complementarity between land uses was found for insects and mammals (around 45 %), contrasting with high complementarity for birds (87 %) and flora (90 %). This suggests substantial turnover and replacement among these ecological environments. Our results indicate that a second rotation (4 year) plantation could accumulate a total of 61.6 Mg C ha-1, and even though adventitious flora represents <2 % of the total carbon accumulated, its importance in providing ecosystem services is considerable. Hence, these findings evidence the fact that SRC poplar plantations can enhance biodiversity in Mediterranean agroforest ecosystems and actively contribute to various provisioning ecosystem services, including carbon sequestration, reflecting a multi-objective approach that extends beyond biomass production.


Asunto(s)
Agricultura , Biodiversidad , Biomasa , Secuestro de Carbono , Carbono , Populus , Agricultura/métodos , Carbono/análisis , Bosques , Ecosistema , Cambio Climático
17.
J Psychiatr Res ; 170: 200-206, 2024 02.
Artículo en Inglés | MEDLINE | ID: mdl-38157667

RESUMEN

INTRODUCTION: This study aims to enhance the understanding of the association between the phenotypic and endophenotypic characteristics of impulsive-aggressive disorders, through the study of plasma oxytocin (OXT) and oxytocin receptor (OXTR) levels in patients with borderline personality disorder (BPD) and patients with eating disorders (ED), as well as to examine the relationship of OXT system with aggressive behavior in these disorders. METHODS: 68 patients with BPD, 67 patients with ED and 57 healthy control subjects were examined for plasma oxytocin levels and protein expression of OXTR in blood mononuclear cells. Aggressive behavior was assessed using the State-Trait Anger Expression Inventory (STAXI-2). Other self and hetero-aggressive behaviors were also evaluated through interviews. RESULTS: BPD and ED patients exhibited significantly lower plasma oxytocin levels than control subjects. Furthermore, BPD patients demonstrated significantly reduced expression of OXTR compared to controls. Plasma oxytocin levels negatively correlated with verbal aggression, while OXTR expression was inversely associated with the STAXI trait subscale. CONCLUSIONS: The findings validate the existence of oxytocin system dysfunction in impulsive-aggressive disorders. They also support the link between low OXT levels in plasma and OXTR expression and the impulsive-aggressive behavior that characterizes these patients in both state and trait situations.


Asunto(s)
Oxitocina , Receptores de Oxitocina , Humanos , Agresión/fisiología , Expresión Génica , Fenotipo , Receptores de Oxitocina/genética
18.
Artículo en Inglés | MEDLINE | ID: mdl-38151169

RESUMEN

INTRODUCTION: Alterations in inflammatory processes have previously been reported in impulsive and unstable disorders, as well as in other psychiatric conditions. In order to investigate transdiagnostic biomarkers associated with various phenotypic features of these disorders, this study is designed to identify biomarkers of inflammatory and oxidative endophenotypes related to autolytic behavior. METHODS: Peripheral blood mononuclear cells were collected from 35 patients with borderline personality disorder (BPD), 29 patients with restrictive eating disorder (rED), 21 patients with purging eating disorder (pED) and 23 control subjects. Plasma levels of different inflammatory and oxidative factors were measured by ELISA and the expression of selected proteins was by Western Blot. Principal component analysis (PCA) was performed to categorize the different inflammatory factors. Additionally, Ancova was performed to observe the differences in the principal components among the different groups and logistic regression analysis was conducted to assess the predictive capacity of these components for autolytic behaviors. RESULTS: We found two inflammatory/oxidative components were associated with BPD, characterized by high levels of JNK and ERK and low levels of GPx, SOD and Keap1; and two other inflammatory/oxidative components were linked to pED, associated with more JNK, TBARS and TNF-α and less GPx and SOD. Two components, with more JNK and ERK and less GPx, SOD and Keap1, predicted non-suicidal self-injury and three components, with higher JNK, TBARS and TNF-α levels and lower GPx, SOD and iNOS levels, predicted suicide attempts. CONCLUSIONS: These results strongly support the endophenotypic characterization of impulsivity and the identification of transdiagnostic inflammatory/oxidative biomarkers relevant to autolytic behavior in impulsive and unstable disorders. These dates lay the groundwork for developing of screening tests for these biomarker components to rapidly detect biological risk factors for specific impulse control disorders and future self-injurious behaviors.


Asunto(s)
Trastorno de Personalidad Limítrofe , Conducta Autodestructiva , Humanos , Proteína 1 Asociada A ECH Tipo Kelch/metabolismo , Leucocitos Mononucleares/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Factor 2 Relacionado con NF-E2/metabolismo , Conducta Autodestructiva/diagnóstico , Conducta Impulsiva , Trastorno de Personalidad Limítrofe/psicología , Biomarcadores/metabolismo , Estrés Oxidativo , Superóxido Dismutasa/metabolismo
19.
Phys Rev Lett ; 111(23): 232503, 2013 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-24476263

RESUMEN

Classical novae are expected to contribute to the 1809-keV Galactic γ-ray emission by producing its precursor 26Al, but the yield depends on the thermonuclear rate of the unmeasured 25Al(p,γ)26Si reaction. Using the ß decay of 26P to populate the key J(π)=3(+) resonance in this reaction, we report the first evidence for the observation of its exit channel via a 1741.6±0.6(stat)±0.3(syst) keV primary γ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured γ-ray energy and intensity with other experimental data on 26Si, we find the center-of-mass energy and strength of the resonance to be E(r)=414.9±0.6(stat)±0.3(syst)±0.6(lit.) keV and ωγ=23±6(stat)(-10)(+11)(lit.) meV, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model 26Al production showing that these measurements effectively eliminate the dominant experimental nuclear-physics uncertainty and we estimate that novae may contribute up to 30% of the Galactic 26Al.

20.
Phys Rev Lett ; 110(12): 122502, 2013 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-25166798

RESUMEN

Long-lived isomers in (212)Bi have been studied following (238)U projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of (212)Bi was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30 min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies.

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