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Low background segmented liquid scintillator detector, doped with an indium as a target for solar neutrino registration, can be used for measuring total solar neutrino spectrum including neutrinos. A detector consisting of small modules filled with liquid scintillator in the volume of 1–2 L is considered. Silicon matrices are used for light collection. The background of indium beta-activity is suppressed by triple coincidences. The detector of such a type can measure Be neutrino flux with high accuracy and independently check the measurement performed by the Borexino Collaboration.

The energy resolution is calculated for a neodymium-containing liquid organic scintillation detector (Nd-OS) with a volume of several liters to search for neutrinoless double beta decay of 150 Nd as a function of the neodymium concentration up to 5 g/L. The results are presented in detailed tables and graphs.

In this paper, the dependence of the sublimation temperature of soot particles synthesized during the combustion of various hydrocarbons, depending on their size and structure, is obtained. The experimental approach is based on the analysis of the thermal radiation of particles heated to the sublimation temperature by a nanosecond laser pulse. The sublimation temperature of soot particles was measured using the two-color pyrometry method. In this paper, it is proposed to use the average size of primary particles to compare data in different flames. It is established, that the sublimation temperature of soot particles depends mainly on the stage of their formation, which is characterized by an increase in average size. It is shown, that with an increase in the average particle size from 12 to 23 nm, their sublimation temperature increases significantly from 2700 to 4500 K. This reflects a significant difference in the thermodynamic and optical properties of the so-called “young” and “mature” soot particles, which must be taken into account when developing methods of soot diagnostics and in the thermo-physical analysis of combustion and pyrolysis processes with the formation of soot.

A discovery that neutrinos are Majorana fermions would have profound implications for particle physics and cosmology. The Majorana character of neutrinos would make possible the neutrinoless double-β (0νββ) decay, a matter-creating process without the balancing emission of antimatter. The GERDA Collaboration searches for the 0νββ decay of 76Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg·year, we observe no signal and derive a lower half-life limit of T 1/2 > 0.9 × 1026 years (90% C.L.). Our T 1/2 sensitivity, assuming no signal, is 1.1 × 1026 years. Combining the latter with those from other 0νββ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 to 0.16 electron volts.

The influence of small additions (0.3-2 ppm) of iron or carbon nanoparticles on ignition delay times in stoichiometric mixture of 20% (methane + oxygen) diluted in argon was investigated. The experiments were performed in 50 mm diameter shock tube behind reflected shock waves. The nanoparticles were synthesized in pyrolysis of 0.5-1% Fe(CO)5 and 1-2% of C6H6 diluted in argon in the experiment before the ignition test. The residual nanoparticles were pulled into the flow behind incident and reflected shock wave from the shock tube walls and their volume fraction was measured by laser light extinction at the wavelength 633 nm. Additions of 0.3-2 ppm of iron nanoparticles to stoichiometric methane-oxygen mixture resulted in twofold decrease of ignition delays at temperatures below 1400 K relatively to calculated and experimental data for the mixture without nanoparticle addition. At additions of 0.4-1 ppm of carbon nanoparticles to stoichiometric methane-oxygen mixture a weak decrease of ignition delay relatively to the calculated data for the mixture without additives of carbon nanoparticles was observed.

In this study the laser-induced incandescence (LII) diagnostics has been applied for sizing of carbon-encapsulated iron nanoparticles (CEINs). The carbon covered iron nanoparticles were synthesized by shock waves pyrolysis of the mixtures of Fe(CO)5 with C2H2 or C6H6 diluted with argon. Iron nanoparticles were formed in the shock tube behind incident shock waves at the temperatures of 700-1000 K. The pyrolysis of hydrocarbons behind reflected shock waves at the temperatures of 1400-2000 K resulted in formation of carbon shell over iron nanoparticles. At the end of the CEINs formation process, particles were heated by one pulse of Nd:YAG laser operated at wavelength 1064 nm with fluences varied in the range 70- 800 mJ/cm2 to collect LII signals. The LII model, which had been used previously for iron and carbon nanoparticles separately, was updated for carbon-encapsulated iron nanoparticles. Additionally, the nanoparticle samples were investigated by a transmission electron microscope (TEM). The iron core size and carbon shell thickness were measured by statistical treatment of microphotographs. The comparison of TEM and LII particle sizing results is discussed.

Many extensions of the Standard Model of particle physics explain the dominance of matter over antimatter in our Universe by neutrinos being their own antiparticles. This would imply the existence of neutrinoless double-β decay, which is an extremely rare lepton-number-violating radioactive decay process whose detection requires the utmost background suppression. Among the programmes that aim to detect this decay, the GERDA Collaboration is searching for neutrinoless double-β decay of Ge by operating bare detectors, made of germanium with an enriched Ge fraction, in liquid argon. After having completed Phase I of data taking, we have recently launched Phase II. Here we report that in GERDA Phase II we have achieved a background level of approximately 10 counts keV kg yr . This implies that the experiment is background-free, even when increasing the exposure up to design level. This is achieved by use of an active veto system, superior germanium detector energy resolution and improved background recognition of our new detectors. No signal of neutrinoless double-β decay was found when Phase I and Phase II data were combined, and we deduce a lower-limit half-life of 5.3 × 10 years at the 90 per cent confidence level. Our half-life sensitivity of 4.0 × 10 years is competitive with the best experiments that use a substantially larger isotope mass. The potential of an essentially background-free search for neutrinoless double-β decay will facilitate a larger germanium experiment with sensitivity levels that will bring us closer to clarifying whether neutrinos are their own antiparticles.

The Gerda collaboration is performing a sensitive search for neutrinoless double beta decay of 76Ge at the INFN Laboratori Nazionali del Gran Sasso, Italy. The upgrade of the Gerda experiment from Phase I to Phase II has been concluded in December 2015. The first Phase II data release shows that the goal to suppress the background by one order of magnitude compared to Phase I has been achieved. Gerda is thus the first experiment that will remain “background-free” up to its design exposure (100 kgyear). It will reach thereby a half-life sensitivity of more than 1026 year within 3 years of data collection. This paper describes in detail the modifications and improvements of the experimental setup for Phase II and discusses the performance of individual detector components.

The experimental investigation of iron-carbon nanoparticles synthesis by joint laser photolysis of iron pentacarbonyl in the mixture with methane or acetylene has been carried out. The radiation source used for photo-dissociation of precursors was a pulsed Nd:Yag laser operated at a wavelength of 266 nm. Under uv radiation the molecules of Fe(CO)5 decomposed, forming atomic iron vapor and unsaturated carbonyls at well-known and readily controllable parameters. The subsequent condensation of supersaturated metal vapor resulted in small iron clusters and nanoparticles formation. It was assumed that the active catalytic surface of metal nanoparticles could activate the hydrocarbon molecules up to carbon layer formation on their surface. The growth process of the nanoparticles was observed by a method of laser light extinction. Additionally nanoparticle samples were investigated by a transmission electron microscope. The particle sizes were measured by microphotographs treatment. The sizes of synthesized particles from methane-iron-pentacarbonyl mixture were found to be in a range of 4-16 nm with a count median diameter of 8.9 nm and standard deviation of 1.13. These particles consisted of iron oxide without any carbon content. The particles formed in photolysis of acetylene-iron-pentacarbonyl mixture had the sizes of 3-7 nm with count median diameter of 4 nm and standard deviation of 1.28 and contained the essential amount of carbon. The iron cores were surrounded with a carbon shell.