Inverse beta decay reaction in 232^{232}Th and 233^{233}U fission antineutrino flux

Energy spectra of antineutrinos coming from $^{232}$Th and $^{233}$U neutron-induced fission are calculated, relevant inverse beta decay $\bar{{\nu}_e}+p \to n + e^{+}$ positron spectra and total cross sections are found. This study is stimulated by a hypothesis that a self-sustained nuclear chain reaction is burning at the center of the Earth ("Georeactor"). The Georeactor, according to the author of this idea, provides energy necessary to sustain the Earth's magnetic field. The Georeactor's nuclear fuel is $^{235}$U and, probably, $^{232}$Th and $^{233}$U. Results of present study may appear to be useful in future experiments aimed to test the Georector hypothesis and to estimate its fuel components as a part of developments in geophysics and astrophysics based on observations of low energy antineutrinos in Nature.Comment: 6 pages in LaTeX and 2 ps figures. Submitted to Physics of Atomic Nucle

Neutrino-induced deuteron disintegration experiment

Cross sections for the disintegration of the deuteron via neutral-current (NCD) and charged-current (CCD) interactions with reactor antineutrinos are measured to be 6.08 +/- 0.77 x 10^(-45) cm-sq and 9.83 +/- 2.04 x 10^(-45) cm-sq per neutrino, respectively, in excellent agreement with current calculations. Since the experimental NCD value depends upon the CCD value, if we use the theoretical value for the CCD reaction, we obtain the improved value of 5.98 +/- 0.54 x 10^(-45) for the NCD cross section. The neutral-current reaction allows a unique measurement of the isovector-axial vector coupling constant in the hadronic weak interaction (beta). In the standard model, this constant is predicted to be exactly 1, independent of the Weinberg angle. We measure a value of beta^2 = 1.01 +/- 0.16. Using the above improved value for the NCD cross section, beta^2 becomes 0.99 +/- 0.10.Comment: 22pages, 9 figure

Компресорні установки

Зміст видання відповідає освітньо-професійній програмі підготовки кадрів з вищою освітою напряму „Електротехніка та електротехнології“, зокрема – програмі дисципліни „Енергетичні установки“. Розглянуто основні положення теорії компресорних машин, будову, експлуатаційні особливості та методи регулювання режиму роботи поршневих, ротаційних, гвинтових, водокільцевих і відцентрових компресорів. Посібник адресовано студентам спеціальності „Енергетичний менеджмент“, які вивчають дисципліну „Енергетичні установки“. Він може бути корисним також студентам напрямів „Гірництво“, „Інженерна механіка“ та „Електромеханіка“ при вивченні стаціонарних установок гірничих підприємств

Inverse Beta Decay in a Nonequilibrium Antineutrino Flux from a Nuclear Reactor

The evolution of the reactor antineutrino spectrum toward equilibrium above the inverse beta-decay threshold during the reactor operating period and the decay of residual antineutrino radiation after reactor shutdown are considered. It is found that, under certain conditions, these processes can play a significant role in experiments seeking neutrino oscillations.Comment: 8 pages including 5 ps figure

Present and Future Experiments in Non-equilibrium Reactor Antineutrino Energy Spectrum

Considerable efforts that have been undertaken in the recent years in low energy antineutrino experiments require further systematic investigations in line of reactor antineutrino spectroscopy as a metrological basis of these experiments. We consider some effects associated with the non-equilibrium of reactor antineutrino radiation and residual antineutrino emission from spent reactor fuel in contemporary antineutrino experiments.Comment: 7 pages, 5 figures; Talk presented at International Conference NANP-2005, Dubna, Russia, Jun.-2005; Submitted to Phys. Atom. Nuc

Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and AZ31 with coincident Doppler broadening spectroscopy

Crystal defects in magnesium and magnesium based alloys like AZ31 are of major importance for the understanding of their macroscopic properties. We have investigated defects and their chemical surrounding in Mg and AZ31 on an atomic scale with Doppler broadening spectroscopy of the positron annihilation radiation. In these Doppler spectra the chemical information and the defect contribution have to be thoroughly separated. For this reason samples of annealed Mg were irradiated with Mg-ions in order to create exclusively defects. In addition Al- and Zn-ion irradiation on Mg-samples was performed in order to create samples with defects and impurity atoms. The ion irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy (DBS) and compared with preceding SRIM-simulations of the vacancy distribution, which are in excellent agreement. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with coincident Doppler broadening spectroscopy (CDBS) by comparing Mg-ion irradiated AZ31 with Mg-ion irradiated Mg. No formation of solute-vacancy complexes was found due to the ion irradiation, despite the high defect mobility.Comment: Submitted to Physical Review B on March 20 20076. Revised version submitted on September 28 2007. Accepted on October 19 200

High-Intensity and High-Brightness Source of Moderated Positrons Using a Brilliant gamma Beam

Presently large efforts are conducted towards the development of highly brilliant gamma beams via Compton back scattering of photons from a high-brilliance electron beam, either on the basis of a normal-conducting electron linac or a (superconducting) Energy Recovery Linac (ERL). Particularly ERL's provide an extremely brilliant electron beam, thus enabling to generate highest-quality gamma beams. A 2.5 MeV gamma beam with an envisaged intensity of 10^15 s^-1, as ultimately envisaged for an ERL-based gamma-beam facility, narrow band width (10^-3), and extremely low emittance (10^-4 mm^2 mrad^2) offers the possibility to produce a high-intensity bright polarized positron beam. Pair production in a face-on irradiated W converter foil (200 micron thick, 10 mm long) would lead to the emission of 2 x 10^13 (fast) positrons per second, which is four orders of magnitude higher compared to strong radioactive ^22Na sources conventionally used in the laboratory.Using a stack of converter foils and subsequent positron moderation, a high-intensity low-energy beam of moderated positrons can be produced. Two different source setups are presented: a high-brightness positron beam with a diameter as low as 0.2 mm, and a high-intensity beam of 3 x 10^11 moderated positrons per second. Hence, profiting from an improved moderation efficiency, the envisaged positron intensity would exceed that of present high-intensity positron sources by a factor of 100.Comment: 9 pages, 3 figure

Components of Antineutrino Emission in Nuclear Reactor

New ${\bar{\nu}_e},e$ scattering experiments aimed for sensitive searches of the ${\nu}_e$ magnetic moment and projects to explore small mixing angle oscillations at reactors call for a better understanding of the reactor antineutrino spectrum. Here we consider six components, which contribute to the total ${\bar{\nu}_e}$ spectrum generated in nuclear reactor. They are: beta decay of the fission fragments of $^{235}$U, $^{239}$Pu, $^{238}$U and $^{241}$Pu, decay of beta-emitters produced as a result of neutron capture in $^{238}$U and also due to neutron capture in accumulated fission fragments which perturbs the spectrum. For antineutrino energies less than 3.5 MeV we tabulate evolution of ${\bar{\nu}_e}$ spectra corresponding to each of the four fissile isotopes vs fuel irradiation time and their decay after the irradiation is stopped and also estimate relevant uncertainties. Small corrections to the ILL spectra are considered.Comment: LaTex 8 pages, 2 ps figure