First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of 163^{163}Ho

The isotope $^{163}$Ho undergoes an electron capture process with a recommended value for the energy available to the decay, $Q_{\rm EC}$, of about 2.5 keV. According to the present knowledge, this is the lowest $Q_{\rm EC}$ value for electron capture processes. Because of that, $^{163}$Ho is the best candidate to perform experiments to investigate the value of the electron neutrino mass based on the analysis of the calorimetrically measured spectrum. We present for the first time the calorimetric measurement of the atomic de-excitation of the $^{163}$Dy daughter atom upon the capture of an electron from the 5s shell in $^{163}$Ho, OI-line. The measured peak energy is 48 eV. This measurement was performed using low temperature metallic magnetic calorimeters with the $^{163}$Ho ion implanted in the absorber. We demonstrate that the calorimetric spectrum of $^{163}$Ho can be measured with high precision and that the parameters describing the spectrum can be learned from the analysis of the data. Finally, we discuss the implications of this result for the Electron Capture $^{163}$Ho experiment, ECHo, aiming to reach sub-eV sensitivity on the electron neutrino mass by a high precision and high statistics calorimetric measurement of the $^{163}$Ho spectrum.Comment: 5 pages, 3 figure

On the keV sterile neutrino search in electron capture

A 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, e.g., 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.Comment: 16 pages, 9 figures, 2 table

A Preliminary Study on SVM based Analysis of Underwater Magnetic Signals for Port Protection

People who attend to the problem of underwater port protection usually use sonar based systems. Recently it has been shown that integrating a sonar system with an auxiliary array of magnetic sensors can improve the effectiveness of the intruder detection system. One of the major issues that arise from the integrated magnetic and acoustic system is the interpretation of the magnetic signals coming from the sensors. In this paper a machine learning approach is proposed for the detection of divers or, in general, of underwater magnetic sources. The research proposed here, by means of a windowing of the signals, uses Support Vector Machines for classification, as tool for the detection problem. Empirical results show the effectiveness of the method

HighSTEPS. A high strain temperature pèressure and speed apparatus to study earthquake mechanics

We present a state of-the-art biaxial apparatus able to study both earthquake rupture nucleation and propagation at conditions typical of the seismogenic crust. The HighSTEPS, High Strain TEmperature Pressure Speed, apparatus simulates fault deformation in a wide range of slip velocities, i.e., from 10-5m/s to 0.25 m/s. Within this velocity range, it is possible to study, the rate-and-state friction, the fault dynamic weakening, and healing under unique boundary conditions, i.e., normal stress up to 100 MPa, confining pressure up to 100 MPa, pore fluid pressure up to 100 MPa and temperature up to 120 °C. The apparatus consists of a hydraulic system integrated with four linear motors. The hydraulic system allows for the application of normal stress, confining pressure and pore fluid pressure. The main peculiarity of this apparatus is the system of four linear motors that are mounted in series in order to apply shearing velocities up to 0.25 m/s, accelerations up to 10 m/s2 and shear stresses up to 200 MPa. Moreover, both experiments in sliding velocity control or shear stress control on the experimental faults are possible. Preliminary experiments on carbonate and silicate bearing rocks are coherent with the previous literature. The investigation of fault friction under a wide range of velocities, normal stresses, confining pressures and pore fluid pressures will provide insights into the mechanics of earthquakes and reduce the gap between natural and laboratory observations

Characterization of the 163^{163}Ho Electron Capture Spectrum: A Step Towards the Electron Neutrino Mass Determination

The isotope $^{163}$Ho is in many ways the best candidate to perform experiments to investigate the value of the electron neutrino mass. It undergoes an electron capture process to $^{163}$Dy with an energy available to the decay, Q$_{EC}$, of about 2.8 keV. According to the present knowledge, this is the lowest Q$_{EC}$ value for such transitions. Here we discuss a newly obtained spectrum of $^{163}$Ho, taken by cryogenic metallic magnetic calorimeters with $^{163}$Ho implanted in the absorbers and operated in anticoincident mode for background reduction. For the first time, the atomic deexcitation of the $^{163}$Dy daughter atom following the capture of electrons from the 5s shell in $^{163}$Ho, the OI line, was observed with a calorimetric measurement. The peak energy is determined to be 48 eV. In addition, a precise determination of the energy available for the decay Q$_{EC}$=(2.858±0.010$_{stat}$±0.05$_{syst}$)  keV was obtained by analyzing the intensities of the lines in the spectrum. This value is in good agreement with the measurement of the mass difference between $^{163}$Ho and $^{163}$Dy obtained by Penning-trap mass spectrometry, demonstrating the reliability of the calorimetric technique

Efecto de la sustitución de maíz (Zea mays L.) por amaranto (Amarantus mantegazzianus cv Don Juan) en dietas de crecimiento y engorde de pollos parrilleros

Se probaron 3 dietas para pollos parrilleros machos, en crecimiento y engorde, a base de maíz y amaranto en distintas proporciones como componentes energéticos principales: (TO: maíz 100%; (T1): amaranto 50%, maíz 50% y (T2): amaranto 100%. Las dietas se formularon con iguales contenidos de proteína y energía: 20,44% PB Y 12,31 MJ E.M./Kg, la de crecimiento y 18,24% PB Y 12,40 MJ E.M./Kg la de engorde. Se evaluaron en 3 repeticiones en un diseño al azar, con 12 pollos por repetición. El T2 se suspendió a los 15 días y se cambió por tilla dieta igual aTO En crecimiento la ganancia diaria media (TO: 41,06 g ± 1,33; T1: 37,5g ± 1,13 y T2: 23,51g ± 0,38) y ganancia semanal media (TO: 287,41g ± 9,37; T1: 262,46g ± 7,97 y T2: 164, 58g ± 2,68) por animal, tuvieron diferencias significativas (p<0,05) entre TO y T1 Y altamente significativas (p<0,01) entre TO y T2. En el consumo diario medio (TO: 88,53g ± 31,84; T1: 88,27g± 39,67 Y T2: 60,33g± 18,5) por animal y enJa eficiencia de conversión alimenticia media (TO: 2,15:1 ± 0,06).Director: Ing. Agr. Raúl Estevez Leyte. Profesor Titular. Codirectores: R.O. Brown y l.E. Cervellini. Profesores Adjuntos. Cátedra de Zootecnia Especial II