A modification of the LENS (Low Energy Neutrino Spectroscopy) project for spectroscopy of solar neutrinos with energies above about 715 keV on the basis of new technologies and solutions is examined. ...The respective detector employs
In nuclei as a target for neutrinos. The creation of a detector containing about 200 t of a scintillator loaded with 10 t of indium will make it possible to measure, within five years, the energy spectra of solar neutrinos from
Be, neutrinos from the CNO cycle, and
neutrinos with small systematic errors. The detector was simulated in the form of a set of cells of a liquid scintillator doped with indium (about 10
in weight). Necessary technical conditions for detector cells are formulated, and the possible counting rate for events induced by internal and external backgrounds and characterized by an energy release of 600 to 1600 keV is estimated. It is shown that such a detector is implementable, in principle.
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.
Evaporation of iron nanoparticles in carbon shells under pulsed laser irradiation is analyzed. Iron–carbon nanoparticles are synthesized in a shock tube reactor with the aid of pyrolysis of the 0.25% ...Fe(CO)
5
+ 0.25% C
6
H
6
mixture in argon. Laser radiation is used for additional heating to temperatures that exceed the evaporation threshold of the iron core of nanoparticles. Time profiles of the thermal radiation of laser-heated nanoparticles are measured. The two-color pyrometry is used to determine the evaporation temperature of nanoparticles, and the laser extinction makes it possible to monitor the loss of volume fraction of the condensed phase upon evaporation. Approximation of experimental signals of laser-heated nanoparticles using model curves is employed to determine effective enthalpy of evaporation of iron–carbon nanoparticles. It is shown that the iron core of nanoparticles is evaporated through the carbon shell and the energy spent by such a process is approximately twice greater than the evaporation enthalpy of bulk iron with free surface.
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.
It is crucial to understand the behavior of the optical properties of soot in the visible and near-IR spectral range to calculate the magnitude of their emission and absorption. Such information also ...helps in the development of diagnostic methods for soot. We measured the absolute value of the refractive index functions of soot nanoparticles
E
(
m
,
1064
) at a wavelength of 1064 nm, as well as the ratio of the refractive index functions at laser wavelengths of 532 nm and 1064 nm in a premixed ethylene/air flame using laser-induced incandescence.
E
(
m
,
1064
) increased with the flame height from 0.29 to 0.43. Depending on the height above the burner, the ratio of
E
(
m
,
1064
)/
E
(
m
,
532
) increased from 0.88 to 1. These changes in the optical properties are attributed to differences in the soot structure, such as the different sizes of graphene planes, which increased from 0.96 to 1.24 nm as the height above the burner increased from 10 to 20 mm. The presented data provide comprehensive information about the optical properties of soot in a premixed ethylene/air flame according to the height above a burner and make it possible to compare measurements of the soot optical properties in various target flames.
Acetylene black is a special type of carbon black, obtained from the thermal decomposition of acetylene. Acetylene flames enable the investigation of the soot optical properties. A reliable knowledge ...of the optical properties of acetylene soot is necessary for interpreting the optical measurements in flames and the development of acetylene black applications in industry. However, a wide variation in the optical properties of soot is observed in different formation conditions. The main factors affecting soot formation in flames are fuel composition, equivalence ratio, and reaction time connected with the height above a burner. In this study, we measured the absolute value of the refractive index function of acetylene soot
E(m,1064)
at a wavelength of 1064 nm, as well as the ratio of the refractive index functions
E(m,1064)
/
E(m,532)
at laser wavelengths of 532 nm and 1064 nm in a premixed acetylene/air flame using laser-induced incandescence. The soot structure was studied using high-resolution electron microscopy. The obtained results showed that
E(m,1064)
increased from 0.19 to 0.53 and that the ratio of
E(m,1064)
/
E(m,532)
increased from 1.12 to 1.55 according to the height above a burner. These changes in the optical properties are attributed to differences in soot structure, such as different distances between graphene planes inside soot crystallites, which decreased from 0.43 to 0.36 nm as the height above the burner increased from 5 to 20 mm. It was concluded that the optical properties and structure of acetylene soot differ from those formed in other hydrocarbon flames.
McKenna burner providing premixed, laminar, steady flat flame is widely used in the combustion community. The ethylene/air flame with equivalent ratio of 2.34 is considered as one of the target ...flames for the development and calibration of optical diagnostics of soot particles. In this work, the accurate soot particle sizing in dependence on the height above a burner was performed using the methods of transmission electron microscopy and laser-induced incandescence. It was found, that shielding co-flow gas type and rate together with small variation of the height of stabilization plate in flat premixed flame burner is not influenced on the center flame temperature and on the soot particle size measurement results. Also, the small variation of the velocity of the cold gas in the 5% range at the same equivalence ratio is not influenced by the results of flame temperature and soot particle size measurements. From the other side, the variation of the burner stabilization plate configuration and material of the sintered plate results in the essential differences of the measured values. The accomplished data analysis resulted in a reliable dependence of soot size in the target flame on the height above a burner, which can be applied for validation of soot formation models.
Because of a high energy of the neutrinoless double-beta decay (0
ν
2
β
) of the isotope
150
Nd and a high value of the daughter-nucleus charge
Z
f
,
150
Nd is one of the most promising isotopes for ...0
ν
2
β
-decay searches. A
150
Nd-containing detector on the basis of a liquid organic scintillator permits employing large isotope masses. Requirements on the radiation purity of the neodymium sample used are determined. The possible design of a large-scale detector of this type and expected results are considered.
This review deals with the UV laser photodissociation of metal carbonyls, ferrocene, carbon suboxide, and other precursors. The formation of supersaturated atomic vapors followed by the formation of ...carbon, metal, and metal–carbon nanoparticles is discussed. Application of UV laser synthesis to preparation of catalytic nanomaterials is considered.
New data on the dependence of the function of the refractive index of soot particles on their average size in the visible and near-IR spectral regions are presented. The data are obtained by ...laser-induced incandescence. The sunlight absorption by soot aerosols is currently calculated with a value of the refractive index function of about 0.2 at a wavelength of 550 nm regardless of the origin of soot particles and their variability. The data demonstrate that optical properties of soot depend on the size of particles and conditions of their formation, which, in turn, is related to the degree of their graphitization. It is shown that taking into account the particle size distribution in soot aerosols can lead to an increase in solar radiation absorption by them approximately by two times as compared to the commonly accepted values.
