98 research outputs found
Characterization of CdS sputtering deposition on low temperature pulsed electron deposition Cu(In,Ga)Se2 solar cells
No full textThe present paper reports the investigation of sputtered CdS as a buffer layer in Cu(In,Ga)Se-2 (CIGS) solar cells, for a dry-low temperature all in-line production technology method. The CdS film is deposited using radio-frequency magnetron sputtering in argon atmosphere. Compared to the well-known CdS grown by chemical bath deposition, the sputtering technology is feasible for the serial manufacturing process. The morphology and optical transmittance of CdS thin films are studied, as well as the CdS/CIGS interface and the solar cell characteristic. We observe that CdS layer deposited on glass is uniform and continuous with optical transmittance above 90% in the wavelengths range corresponding to the energy gap of the absorber. Current density-voltage (J-V) curve shows an overall efficiency of 6% affected by inhomogeneity at the CIGS/CdS interface. Sputtering deposition is not able to create a homogeneous layer on the absorber irregularities due its growth process. Moreover, Auger depth profile shows oxygen contamination at the interface, due to absorber surface oxidation. Within this work, the main crucial aspects of a new solar cell production technology, as well as related solutions, are reported
Biophotons: new experimental data and analysis
No full textArticle describes how biophotons are an ultra-weak emission of photons in the visible energy range from living matter. The authors study the emission from germinating seeds using an experimental technique designed to detect light of extremely small intensity
Biophotons: a hard problem
No full textAbout a hundred years ago, the Russian biologist A. Gurwitsch, based on experiments with onion plants by measuring their growth rate, hypothesized that plants emit a weak electromagnetic field that somehow influences cell growth. This interesting observation remained fundamentally ignored by the scientific community; only in the 1950s the electromagnetic emission from some plants was measured using a photomultiplier used in single counting mode. Later, in the 1980s, several groups around the world started extensive work to understand the origin and role of this ultraweak emission, now called biophotons, coming from living organisms. Biophotons are an endogenous very small production of photons in the visible energy range in and from cells and organisms, and this emission is characteristic of living organisms. Today, there is no doubt that biophotons exist, this emission has been measured by many groups and for many different living organisms, from humans to bacteria. However, the origin of biophotons and whether organisms use them to exchange information is not yet well understood; no model proposed to date is capable of reproducing and interpreting the great variety of experimental data coming from the many different living systems measured so far. In this brief review, we present our experimental work on the biophotons coming from germinating seeds, the main experimental results, and some new methods we are using to analyze the data to open the door for interpretative models of this phenomenon clarifying its function in the regulation and communication between cells and living organisms. We also discuss ideas on how to increase the signal-to-noise ratio of the measured signal to open up new experimental possibilities that allow the measurement and the characterization of currently unmeasurable quantities
Biophotons-and-emergence-of-quantum-coherencea-diffusion-entropy-analysisEntropy
No full textThis article studies the emission of photons from germinating seeds using an experimental technique designed to detect light of extremely small intensity. It analyzes the dark count signal without germinating seeds as well as the photon emission during the germination process
Manejo del agua en la Huerta Demostrativa de la Universidad Católica de Santiago del Estero
No full textHorticulture depends, among other requirements, on the availability of water at every stage of crops development. In order to adjust frequency and volume irrigated, an exploratory trial was carried out in the Demonstration Vegetable Garden at the Universidad Católica de Santiago del Estero. Water availability was registered by electronic sensors, installed at different depths (15, 30, 45 and 60cm). Measurements of water content were carried out in two irrigation situations, 24 hours after water saturation of the soil and after 3 days without water supply, in order to obtain information on its moisture retention capacity. Values registered by the sensors were contrasted with real data of moisture content measured in field and laboratory by extracting and drying soil samples. Results obtained indicated: i) an adjustment in the reading of the sensors is needed (a value 10 % higher than the real one was registered), and ii) loss of moisture due to percolation was 20 % in the first 30cm, reducing to 15 % and 10 % at 45 and 60cm, respectively.La actividad hortícola depende, entre otros requerimientos, de la disponibilidad de agua en cada etapa de desarrollo de los cultivos, por lo cual debe ajustarse la frecuencia y el volumen regado. Con la finalidad de ajustar estos parámetros en la Huerta Demostrativa de la Universidad Católica de Santiago del Estero se llevó adelante un ensayo exploratorio. Fueron instalados sensores electrónicos a distintas profundidades (15, 30, 45 y 60cm) a fin de evaluar la disponibilidad de agua. Se realizaron mediciones del contenido hídrico en dos situaciones de riego, a capacidad de campo y luego de 3 días sin provisión de agua, a fin de obtener información sobre la capacidad de retención de humedad de ese suelo. Se logró contrastar los valores obtenidos mediante sensores y la información del fabricante, valiéndose de datos reales de contenido de humedad medidos a campo y en laboratorio mediante la extracción y secado de muestras de suelo. Los resultados obtenidos indicaron: i) la necesidad de un ajuste en la lectura de los sensores (arrojaban un valor 10 % mayor que el real), y ii) la pérdida de humedad por percolación fue de un 20 % en los primeros 30cm, reduciéndose a 15 % y 10 % a los 45 y 60cm respectivamente
Characterization of the SIDDHARTA-2 Setup via the Kaonic Helium Measurement
No full textThe aim of the SIDDHARTA-2 experiment is to perform the first measurement ever of the width and shift induced by the strong interaction to the 2p -> 1s energy transition of kaonic deuterium. This ambitious goal implies a challenging task due to the very low X-ray yield of kaonic deuterium, which is why an accurate and thorough characterization of the experimental apparatus is mandatory before starting the data-taking campaign. Helium-4 is an excellent candidate for this characterization since it exhibits a high yield in particular for the 3d -> 2p transition, roughly 100 times greater than that of the kaonic deuterium. The ultimate goal of the work reported in this paper is to study the performances of the full experimental setup in view of the kaonic deuterium measurement. This is carried out by measuring the values of the shift and the width for the 3d -> 2p energy transition of kaonic helium-4, induced by the strong interaction. The values obtained for these quantities, for a total integrated luminosity of similar to 31/pb, are epsilon 2p=2.0 +/- 1.2(stat)+/- 1.5(syst)eV and Gamma 2p=1.9 +/- 5.7(stat)+/- 0.7(syst)eV. The results, compared to the value of the shift measured by the SIDDHARTA experiment epsilon 2p=0 +/- 6(stat)+/- 2(syst)eV, show a net enhancement of the resolution of the apparatus, providing strong evidence of the potential to perform the challenging measurement of the kaonic deuterium
A Novel Approach to Parameter Determination of the Continuous Spontaneous Localization Collapse Model
No full textModels of dynamical wave function collapse consistently describe the breakdown of the quantum superposition with the growing mass of the system by introducing non-linear and stochastic modifications to the standard Schrödinger dynamics. Among them, Continuous Spontaneous Localization (CSL) was extensively investigated both theoretically and experimentally. Measurable consequences of the collapse phenomenon depend on different combinations of the phenomenological parameters of the model—the strength λ and the correlation length rC—and have led, so far, to the exclusion of regions of the admissible (λ−rC) parameters space. We developed a novel approach to disentangle the λ and rC probability density functions, which discloses a more profound statistical insight
Testing Pauli Exclusion Principle for electrons at the LNGS underground laboratory: The VIP-2 experiment
No full textThe VIP-2 experiment tests the Pauli Exclusion Principle (PEP) for electrons at the Gran Sasso underground National Laboratory (LNGS) of INFN in Italy, looking for a possible violation. The LNGS provide an extremely low background environment, ideal for performing high precision X-ray spectroscopy measurements on electrons atomic transitions.
The core of the VIP-2 experimental apparatus is based on a copper target circulated by a Direct Current (DC) and surrounded by silicon drift detectors (SDDs), which offer excellent performance in X-ray spectroscopy in the energy range experimentally observed by VIP-2. The aim of VIP-2 is to look for eventual PEP-forbidden K_α transitions (2p → 1s) in copper atoms, when the 1s level would be already occupied by two electrons, in contradiction with PEP. The energy of the K_α forbidden transitions is about 300 eV less than the nominal energy of the K_α PEP-allowed transition. This energy shift is due to the screening effect produced by the extra electron in fundamental level, and is detectable by means of a high precision X-ray spectroscopy measurement. About ten years ago, the VIP experiment set the best upper limit on the PEP violation probability β^2/2 < 4.7 × 10^−29 for electrons. The goal of the VIP-2 experiment is to improve this limit by two orders of magnitude. This paper presents a new preliminary result, obtained by analysing two sets of data collected with a partial configuration of the VIP-2 apparatus
Semi-Analytical Monte Carlo Method to Simulate the Signal of the VIP-2 Experiment
No full textThe VIP-2 collaboration runs an apparatus in the Gran Sasso underground laboratories of the Italian Institute for Nuclear Physics (INFN) designed to search for anomalous X-rays from electron-atom interactions due to violations of the fundamental antisymmetry of multi-electron wavefunctions. The experiment implements the scheme first proposed by Ramberg and Snow, where a current source injects electrons into a metal strip (the experiment’s target). In this paper we describe the structure of a Monte Carlo program to simulate a new upgrade of the experiment, where the anomalous X-ray emission is modulated by an arbitrary time-varying input current. A novel feature of the simulation algorithm is that the Monte Carlo program is based on a mixture of analytical and numerical methods. We report preliminary, exploratory results on the expected detection rate for different modulations of the injected current; these results are a starting point on the way to optimize the modulation scheme and indicate a large potential improvement of the detection sensitivity
Testing the Pauli Exclusion Principle across the Periodic Table with the VIP-3 Experiment
No full textThe Pauli exclusion principle (PEP), a cornerstone of quantum mechanics and whole science, states that in a system, two fermions can not simultaneously occupy the same quantum state. Several experimental tests have been performed to place increasingly stringent bounds on the validity of PEP. Among these, the series of VIP experiments, performed at the Gran Sasso Underground National Laboratory of INFN, is searching for PEP-violating atomic X-ray transitions in copper. In this paper, the upgraded VIP-3 setup is described, designed to extend these investigations to higher-Z elements such as zirconium, silver, palladium, and tin. We detail the enhanced design of this setup, including the implementation of cutting-edge, 1 mm thick, silicon drift detectors, which significantly improve the measurement sensitivity at higher energies. Additionally, we present calculations of expected PEP-violating energy shifts in the characteristic lines of these elements, performed using the multi-configurational Dirac–Fock method from first principles. The VIP-3 realization will contribute to ongoing research into PEP violation for different elements, offering new insights and directions for future studies
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