KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

First Results from KamLAND: Evidence for Reactor Anti-Neutrino Disappearance

This paper presents a comprehensive geoneutrino measurement using the Borexino detector, located at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The analysis is the result of 3262.74 days of data between December 2007 and April 2019. The paper describes improved analysis techniques and optimized data selection, which includes enlarged fiducial volume and sophisticated cosmogenic veto. The reported exposure of (1.29±0.05)×1032 protons ×year represents an increase by a factor of two over a previous Borexino analysis reported in 2015. By observing 52.6-8.6+9.4(stat)-2.1+2.7(sys) geoneutrinos (68% interval) from U238 and Th232, a geoneutrino signal of 47.0-7.7+8.4(stat)-1.9+2.4(sys) TNU with  -17.2+18.3% total precision was obtained. This result assumes the same Th/U mass ratio as found in chondritic CI meteorites but compatible results were found when contributions from U238 and Th232 were both fit as free parameters. Antineutrino background from reactors is fit unconstrained and found compatible with the expectations. The null-hypothesis of observing a geoneutrino signal from the mantle is excluded at a 99.0% C.L. when exploiting detailed knowledge of the local crust near the experimental site. Measured mantle signal of 21.2-9.0+9.5(stat)-0.9+1.1(sys) TNU corresponds to the production of a radiogenic heat of 24.6-10.4+11.1  TW (68% interval) from U238 and Th232 in the mantle. Assuming 18% contribution of K40 in the mantle and 8.1-1.4+1.9  TW of total radiogenic heat of the lithosphere, the Borexino estimate of the total radiogenic heat of the Earth is 38.2-12.7+13.6  TW, which corresponds to the convective Urey ratio of 0.78-0.28+0.41. These values are compatible with different geological predictions, however there is a ∼2.4σ tension with those Earth models which predict the lowest concentration of heat-producing elements in the mantle. In addition, by constraining the number of expected reactor antineutrino events, the existence of a hypothetical georeactor at the center of the Earth having power greater than 2.4 TW is excluded at 95% C.L. Particular attention is given to the description of all analysis details which should be of interest for the next generation of geoneutrino measurements using liquid scintillator detectors.

Comprehensive geoneutrino analysis with Borexino

Extragalactic sources of high-energy cosmic gamma-rays, like blazars and quasars, are usually highly variable and the temporal characteristics of their light curves are key to the understanding of their physics. In order to deal with blazar flares in different parts of electromagnetic spectrum – from gamma-rays and X-rays to visible light - we developed a new approach to correlation study based on Monte Carlo simulations and the Fourier convolution.

http://inspirehep.net/record/1395730/files/DHrupec.pdf

Extragalactic sources of rapidly variable high energy gamma radiation

Using data obtained with neutron monitors and space-borne instruments, we analyzed the second ground-level enhancement (GLE) of Solar Cycle 24, namely the event of 10 September 2017 (GLE 72), and derived the spectral and angular characteristics of associated GLE particles. We employed a new neutron-monitor yield function and a recently proposed model based on an optimization procedure. The method consists of simulating particle propagation in a model magnetosphere in order to derive the cutoff rigidity and neutron-monitor asymptotic directions. Subsequently, the rigidity spectrum and anisotropy of GLE particles are obtained in their dynamical evolution during the event on the basis of an inverse-problem solution. The derived angular distribution and spectra are discussed briefly.

First Analysis of Ground-Level Enhancement (GLE) 72 on 10 September 2017: Spectral and Anisotropy Characteristics

Recently there has been renewed interest in the evolution of the inner core and in the possibility that radioactive potassium might be found in significant quantities in the core. The arguments for core potassium come from considerations of the age of the inner core and the energy required to sustain the geodynamo (Nimmo, F., Price, G.D., Brodholt, J., Gubbins, D., 2004. The influence of potassium on core and geodynamo evolution. Geophys. J. Int. 156, 363-376; Labrosse, S., Poirier, J.-P., Le MouJ.-L., 2001. The age of the inner core. Earth Planet Sci. Lett. 190, 111-123; Labrosse, S., 2003. Thermal and magnetic evolution of the Earth's core. Phys. Earth Planet Int. 140, 127-143; Buffett, B.A., 2003. The thermal state of Earth's core. Science 299, 1675-1677) and from new high pressure physics analyses (Lee, K., Jeanloz, R., 2003. High-pressure alloying of potassium and iron: radioactivity in the Earth's core? Geophys. Res. Lett. 30 (23); Murthy, V.M., van Westrenen, W., Fei, Y.W., 2003. Experimental evidence that potassium is a substantial radioactive heat source in planetary cores. Nature 423, 163-165; Gessmann, C.K., Wood, B.J., 2002. Potassium in the Earth's core? Earth Planet Sci. Lett. 200, 63-78). The Earth's core is also located at the lower boundary of the convecting mantle and the presence of radioactive heat sources in the core will affect the flux of heat between these two regions and will, as a result, have a significant impact on the Earth's thermal history. In this paper, we present Earth thermal history simulations in which we calculate fluid flow in a spherical shell representing the mantle, coupled with a core of a given heat capacity with varying degrees of internal heating in the form of 40 K and varying initial core temperatures. The mantle model includes the effects of the temperature dependence of viscosity, decaying radioactive heat sources, and mantle phase transitions. The core model includes the thermal effects of inner core solidification and we present models for which the final size of the inner core is the same that for the present-day Earth. We compare the results of simulations with and without the effects of inner core solidification and we compare the results of the numerical model with those of a parameterized model. Models with concentrations of potassium in the core of roughly 600 ppm best satisfy the present-day surface heat flow constraint; however, the core temperatures in these models are somewhat high. In addition, we find that models with lesser degrees of heating in the core can also satisfy the surface heat flow constraint provided that the mantle is in a particularly active state. Our models predict a relatively young inner core with the greatest age being 1756 Ma. We demonstrate that models with high core temperatures

Numerical models of the Earth's thermal history

A new method for energy and mass composition estimation of primary cosmic rays based on the atmospheric Cherenkov light flux in extensive air showers (EAS) is proposed. The Cherenkov light flux in EAS initiated by primary protons and iron nuclei is simulated with the CORSIKA 5.62 code for the Chacaltaya observation level (536 g / cm 2 ) in the energy range 10 TeV – 10 PeV . An adequate model for the lateral distribution of Cherenkov light in showers is obtained. Using the model and a solution for the overdetermined system of nonlinear equations based on the Gauss–Newton method with autoregularization, two different detector arrangements are compared. The accuracies in energy and shower axis determination are studied and the corresponding selection criteria are proposed. An approximation with a nonlinear fit is obtained and the energy dependence of the proposed model parameters is studied. A detailed study of the model parameters as a function of the primary energy is made. This permits, taking into account the properties of the proposed method and the strong nonlinearity of the model, a distinction to be made between proton and iron primaries. The detector response for the detector sets is simulated and the accuracies in energy determination are calculated. In addition, the accuracies in shower axis determination are studied and criteria for shower axis position estimation are proposed.

A method for energy estimation and mass composition determination of primary cosmic rays at the Chacaltaya observation level based on the atmospheric Cherenkov light technique

. The local "when" for earthquake prediction is based on the connection between geomagnetic "quakes" and the next incoming minimum or maximum of tidal gravitational potential. The probability time window for the predicted earthquake is for the tidal minimum approximately ±1 day and for the maximum ±2 days. The preliminary statistic estimation on the basis of distribution of the time difference between occurred and predicted earthquakes for the period 2002-2003 for the Sofia region is given. The possibility for creating a local "when, where" earthquake research and prediction NETWORK is based on the accurate monitoring of the electromagnetic field with special space and time scales under, on and over the Earth's surface. The periodically upgraded information from seismic hazard maps and other standard geodetic information, as well as other precursory information, is essential.

/pdf/on-the-reliability-of-the-geomagnetic-quake-as-a-short-time-8a1qr1qisy.pdf

On the reliability of the geomagnetic quake as a short time earthquake's precursor for the Sofia region

In this paper we present a new method for ground based gamma rayastronomy based only on atmospheric Cherenkov light flux analysis. The Cherenkovlight flux densities in extensive air showers (EAS) initiated by different primaries aresimulated, precisely primary protons in the energy range 100 GeV – 100 PeV,primary gamma quanta in the energy range 10 GeV – 10 PeV and primary iron nucleiin the energy range 10 TeV –100 PeV using the CORSIKA 6 code at high mountainobservation level of 536 g/cm 2 .An approximation of lateral distribution of Cherenkov light in extensive air showers isobtained. The obtained approximation is a nonlinear fit such as Breit-Wigner withfew parameters. A detailed study of the energy dependence of the proposed modelfunction parameters is carried out and the fit of model parameters as a function of theprimary energy is obtained as well. On the basis of the difference between the modelparameters, precisely their behavior as a function of the energy, the strong nolinearity of the model, we propose a method, which permits to make the distinctionbetween gamma ray primaries from hadronic primaries. The possible backgroundsfor ground based gamma ray astronomy are studied and the efficiency of the methodis calculated.Different detector displacements are analyzed using the simulation of simplified massspectrum of cosmic ray. The detector response is simulated taking into account thephysical fluctuation of the processes, the statistical and possible systematic errors.The simulated and reconstructed events are compared and the accuracy in energy andprimary mass reconstruction is obtained. Moreover the accuracy in shower axisdetermination is studied and criteria in shower axis position estimation are proposed.1.IntroductionThe discoveries from space-borne and ground-based instruments have revolutionizedthe field of gamma-ray astronomy. One of the most exciting challenges in this field isthe exploitation in a region of the gap between ground based and space bornexperiments. Currently gamma-ray energies between 20 and 250 GeV are notaccessible to both space-borne detectors,and ground-based air Cherenkov detectors.The scientific potential of the ground based gamma ray astronomy is enormous andcovers both astrophysics and fundamental physics. In one hand it is possible to studyobjects such as supernova remnants, active galactic nuclei and pulsars. On the otherthe observations especially in the range of low energies will help to understand wellthe various acceleration mechanisms assumed to be at the origin of very high energygamma quanta. Several in development projects are based on image technique such asMAGIC [1], HESS [2] and VERITAS [3] are designed to study such type of problemsas well. Our aim is to propose an alternative method, also based on atmosphericCherenkov light registration.The reconstruction of the lateral distribution ofCherenkov light flux in EAS and therefore selection of gamma quanta induced signalsfrom nuclei induced background is the basis of the alternative methods for primarygamma ray study. In the mentioned above energy range taking into account the

Ground based Gamma Ray Studies based on Atmospheric Cherenkov technique at high mountain altitude

We formalized the nuclear mass problem in the inverse problem framework. This approach allows us to infer the underlying model parameters from experimental observation, rather than to predict the o...

S. Cht. Mavrodiev

Papers

A method for energy estimation and mass composition determination of primary cosmic rays at the Chacaltaya observation level based on the atmospheric Cherenkov light technique

On the reliability of the geomagnetic quake as a short time earthquake's precursor for the Sofia region

Ground based Gamma Ray Studies based on Atmospheric Cherenkov technique at high mountain altitude

Modification of the nuclear landscape in the inverse problem framework using the generalized Bethe–Weizsäcker mass formula

Quantization in classical mechanics and its relation to the Bohmian Ψ-field