Search

We present a novel approach to Correlation Plenoptic Imaging (CPI), named CPI between arbitrary planes. This approach allows a tridimensional reconstruction of the scene around two distinct arbitrary planes conjugate to the correlated sensors.

This article presents the measurements of the luminescence and scintillation under X-ray of undoped, Si-doped, and Si, B codoped gallium-arsenide (GaAs) samples at cryogenic temperature over a wide infrared (IR) region using Si and InGaAs photodetectors. The undoped GaAs has a narrow emission band at 838 nm (1.48 eV) and a low light output of about 2 ph/keV. The GaAs:Si has three broad luminescence bands at 830 nm (1.49 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) and a light output of about 67 ph/keV. GaAs:(Si, B) has four luminescence bands at 860 nm (1.44 eV), 930 nm (1.33 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) with a light yield of approximately 119 ph/keV. With advances in photodetection, GaAs promises to be a useful cryogenic scintillator for the detection of electron recoils from MeV/c2 dark matter.

Thermally stimulated luminescence (TSL) measurements with spectral resolution on undoped NaI and NaI doped with Tl, In, and Eu are presented and analyzed. Based on the trap parameters extracted, ca...

In this work, we experimentally explore the possibility to realize a sensor whose basic building block is a laser cavity that hosts a target crystal for the incident ionizing radiation. Two possible detection mechanisms are considered: a process of coherent scintillation related to the rapid decay via stimulated emission of the excited atomic or molecular levels of the target material and the activation of states that absorb intracavity photons. We use a solid-state laser to study the dynamic response of our prototype sensor and the related intrinsic limitations and demonstrate capability to detect x-ray energy down to 10 GeV.

The emission spectrum of Erbium-doped fluoride crystals excited by soft X-rays in the (400–1700) nm wavelength range is investigated between 3.2 K and 300 K. The largest component of the crystals emission is observed in the infrared range, which corresponds to a light yield of several tens of photons/keV. Such a large value is caused by energy transfer processes between the Erbium ions which convert the excitation of a dopant ion at high energies into the emission of multiple infrared photons. The present results show that this mechanism could be exploited to realize scintillators of high light yield.

The measurement in 2014 of the nonproportionality of each decay component in CsI:Tl found opposite slopes of the fast and tail nonproportionality curves above about 10 keV. Somewhat earlier experiments on nonproportionality and resolution versus shaping time in NaI:Tl and CsI:Tl showed that proportionality and intrinsic resolution could be improved by including the slower “tail” component of the scintillation pulse. The observed opposing nonproportionality trends of fast and tail components constitute a basis for improvement of scintillator nonproportionality if they are added in a suitable linear combination. We examine whether combining the rise and decay components pulse by pulse with an algorithm of optimized proportions may also improve energy resolution. The premise is that a scintillation pulse carries more information about the particle stopping event than is conveyed in a simple measurement of the pulse height. In this work, we measured pulse shapes of individual gamma events in CsI:Tl and other scintillators using an eMorpho multichannel analyzer as a digital oscilloscope. Decomposition of every scintillation pulse into a rise and three exponential decay components allowed us to represent the pulse height spectrum as a linear combination of them. We found that energy resolution of CsI:Tl can be altered and improved through changing the weight of decay components in the linear combination.

Determination of neurophysiological features of the disease course in patients with paroxysmal atrial fibrillation (AF); pathogenetic validation of use and assessment of therapeutic efficacy of clonazepam (an atypical agonist of benzodiazepine receptors) in combined antiarrhythmic therapy.The study group consisted of 31 patients with paroxysmal AF free of severe organic changes of the myocardium with twice a week paroxysms, on the average, treated ineffectively with beta-adrenoblockers, amiodaron, sotalol, etacisine, allapinin or combination of the above drugs. A comparative group consisted of 10 patients with perpetual arrhythmia. Fifteen healthy subjects entered the control group. Electroencephalograms were made on the unit Brain Surfing (Russia). Compression-spectral analysis was conducted with utilization of Fourier's algorithm in different periods of the disease for calculation of the absolute (mcV2/Hz) spectral power of the teta- (4.0-7 Hz), alpha (8-13 Hz) and beta-rhythm (14-18 Hz). Clonazepam was given in a dose 1.5 mg/day in addition to insufficiently effective anti-arrhythmic therapy. Holter ECG monitoring was carried out initially and in therapy with clonazepam.The spectral power of alpha-, beta- and teta-rhythm of patients with paroxysmal AF exhibits significant cyclic fluctuations depending on the disease course period. In attack-free period AF patients differ from healthy subjects by a significant fall of spectral power of beta-rhythm indicating functional deficiency of the reticular formation in this disease. 0-24 hours before AF paroxysm spectral power of all the rhythms rose greatly reflecting marked functional disintegration of nonspecific brain systems realizing psychovegetative regulation. At AF paroxysm spectral power of alpha- and beta-rhythm significantly decreased while that of teta-rhythm grew (activation of the lymbic complex). 0-24 h after paroxysm spectral power of alpha- and beta-rhythm continued to fall, of teta-rhythm--sharply fell. Spectral EEG characteristics in this period maximally approached those of the control group. Clonazepam treatment decreased the paroxysms two times and more in 58.1% patients. Holter ECG showed associated reduction in the number of supraventricular extrasystoles by 81.9%. The compression-spectral ECG analysis revealed a 12% enhancement of beta-rhythm spectral power showing lessening of functional disintegration of nonspecific brain systems.The course of paroxysmal AF is characterized by functional disintegration of nonspecific brain systems (thalamo-cortical, lymbic and mesencephalic reticular formation) which is maximally evident before AF paroxysm and attenuates after it. Cyclic changes in functional activity are a neurogenic factor realizing readiness of the atria to fibrillation. An atypical agonist of benzodiazepine receptors clonazepam effectively influences neurogenic mechanisms provoking AF paroxysms.

The subjects of the study were 32 patients with paroxysmal atrial fibrillation (AF) and 19 ':ealthy individuals using a clinical and neurophysiological method of toposelective mapping of electroencephalogram (EEG). EEG was done during the inter-attack, pre-attack, and post-attack periods, as well as during a paroxysm. During the inter-attack period, the patients had a lower beta-rhythm power vs. the healthy controls, while there were no significant differences between them in the power of alpha- and beta-activity. Before an attack, the patients had a significant increase in beta, alpha-, and theta-range power, reflecting the intensification of the activity of the metaencephalic reticular formation, thalamocortical, and hypothalamosepto-hyppocampal systems, respectively. During an AF paroxysm, the activity of the thalamocortical and reticular systems was lowered, while the activity of the hypothalamo-hyppocampal system further increased. After an attack, the activity of all the mentioned systems went down to the initial state of the "optimal" brain functioning after an excessive excitation. It is assumed that generalized one-way direction of EEG changes before an attack reflects tensed functioning of practically all activation systems, which increases the probability of a "breakdown" in a form of an AF paroxysm. The data of the study evidence a cyclic character of the disease and stresses an important role in AF pathogenesis played by disturbances associated with the functional condition of non-specific temporal-limbic and reticular brain structures, especially in patients without organic myocardial alterations.