•The first synchronously pumped picosecond all-solid-state SrMoO4 laser•Laser generation at 887 cm−1 and 327 cm−1 Raman shifts in the transient regime•The generated pulse duration close to dephasing ...time of 1 ps•Pulse shortening from 36 ps down to 1 ps
We report characteristics of a synchronously pumped picosecond all-solid-state Raman laser based on a SrMoO4 crystal at both 887 cm−1 stretching and 327 cm−1 bending anionic group symmetric vibrations. Lasing is obtained at not only the first Stokes wavelength of 1173 nm having a usual Raman shift of 887 cm−1 from the 1063-nm pumping, but also at the additional Stokes wavelength of 1220 nm with the combined 887 cm−1 + 327 cm−1 Raman shift. The strongest 26-fold shortening of the 1220-nm Raman radiation pulse down to 1.4 ps is achieved. This is close to very short dephasing time (1 ps) of the 327 cm−1 vibrational Raman line of the SrMoO4 crystal due to self-mode-locking of the 1220-nm cascaded Stokes field under intracavity pumping by the 1173-nm fundamental Stokes field.
The stages of development and the current status of the versatile “Spectrometer with a Vertex Detector” setup designed for physics experiments at the U-70 accelerator of the Institute for High Energy ...Physics (Protvino) is described. The main detectors of the setup are the vertex detector based on silicon microstrip detectors, the wide-aperture magnetic spectrometer based on multiwire proportional chambers, and the lead-glass hodoscope γ detector. In the setup, there is a fast two-level trigger system for selecting required particle interactions. The key characteristics of the setup systems are presented, and the physical results obtained on it are briefly listed.
Status of the GAMMA-400 project Galper, A.M.; Adriani, O.; Aptekar, R.L. ...
Advances in space research,
01/2013, Letnik:
51, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100MeV–3TeV is presented. The angular resolution of the instrument, 1–2° at Eγ∼100MeV and ∼0.01° at ...Eγ>100GeV, its energy resolution ∼1% at Eγ>100GeV, and the proton rejection factor ∼106 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.
The article presents results of studying the distribution of alien species on the territory of six districts of Zhetysu oblast, located in the Southeastern Kazakhstan. The data obtained will make it ...possible to summarize up-to-date information about the state of ecosystems with invasive plant species, predict their further spread, and develop a strategy to control them. The objects of research were natural ecosystems of Zhetysu oblast, confined to the Balkhash-Alakol and Zhongar-Alatau floristic districts. To identify alien species, monitoring sites were laid with the calculation of native species, introduced species, the species prone to naturalization, and those with self-seeding. The aggressiveness of naturalized species was assessed according to a modernized scale developed at the Institute of Botany and Phytointroduction, Committee of Forestry and Wildlife, Ministry of Ecology, Geology, and Natural Resources of the Republic of Kazakhstan. The territory under study includes two State National Nature Parks and a State Nature Reserve. Eighty-one alien species of woody plants have been identified within settlements and adjacent territories. Some of them are included in the cultivated flora, which do not show a tendency to naturalization in the region. Seventeen species of alien woody plants have been identified in natural ecosystems, which have the potential for naturalization with a high propensity for seed and vegetative reproduction. The percentage of sites with the presence of invasive species varies from 61 to 91%. The highest aggressiveness score (6–8) was assigned to six species:
Acer negundo
L.,
Ulmus pumila
L.,
Quercus robur
L.,
Prunus
×
domestica
,
Fraxinus pennsylvanica
,
Ulmus laevis
Pall
.
. Despite the fact that, in the Alakol and Sarkand districts, most of the territory falls within the dry-steppe and semidesert zones, only 8.6% of sites without types of invasive fraction were noted, owing to widespread dispersion of particularly aggressive “edificators”:
A. negundo
,
U. pumila
, etc. All identified species mesophytic by their nature in the secondary range show themselves highly adaptive, plastic, and competitive in xerophytic conditions.
We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above ~70 MeV performed by the PAMELA mission at low Earth orbits (350 / 610 km). Data were analyzed ...in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra, and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes, placing important constraints on the trapping and interaction processes, and can be used to validate current trapped particle radiation models.
•The first synchronously pumped picosecond SrWO4 laser.•Efficient generation at 921 cm−1 and 921 cm−1 + 336 cm−1 Raman shifts in the transient regime.•Pulse shortening from 36 ps down to 1.4 ps.•The ...generated pulse duration close to the vibrational dephasing time of 1.2 ps.
We report characteristics of a synchronously pumped picosecond all-solid-state Raman laser based on a SrWO4 crystal at both stretching (ν1 = 921 cm−1) and bending (ν2 = 336 cm−1) anionic group symmetric vibrations. Lasing is obtained at not only the first Stokes wavelength of 1178 nm having a usual Raman shift of ν1 from the 1063-nm pumping, but also at the additional Stokes wavelength of 1227 nm with the combined (ν1 + ν2) Raman shift. The strongest 26-fold shortening of the (ν1 + ν2)-shifted Raman radiation pulse down to 1.4 ps is achieved close to very short dephasing time (1.2 ps) of the ν2 vibrational Raman mode. This is similar to the recently reported synchronously-pumped SrMoO4 Raman laser, but the output energy characteristics of the new SrWO4 Raman laser are essentially higher. At the ν1-shifted Raman component we have obtained the output pulse energy and slope efficiency of 40 nJ and 45%, respectively. At the (ν1 + ν2)-shifted Raman component these characteristics are 15 nJ and 18%, respectively, that is 5 times higher than those in the SrMoO4 laser.
Heating of the magnetic nanoparticles in AC magnetic field is the effect promising for application in medicine. The mechanisms of heating in AC-magnetic field implies nontrivial dependence of the ...power dissipated by magnetic nanoparticles on frequency. With the use of a reconfigurable experimental setup, this frequency-dependent magnetic heating was measured on two characteristic examples: the magnetite nanoparticles conventionally used in medicine and polymer coating with micrometer sized magnetite particles. The saturation of the heating power with frequency is shown that is more pronounced for the second case of microparticles.
The glasses in the ZrF4–BiF3–BaF2 system with different content of bismuth trifluoride have been investigated. The trends of the decrease of glass transition and crystallization temperatures along ...with the increase of the BiF3 content in glass, the presence of more than one crystallization peak and composition of crystalline phases in glasses have been revealed. All the studied glasses of the fluorozirconate series have nanosized heterogeneities of virtually the same scale. The crystallization process depends on the bismuth trifluoride content in glass. The contribution of photoluminescence of bismuth with transition emission 540nm was found for the glass doped with 1% Bi.
•The glasses in the ZrF4–BiF3–BaF2 system have been synthesized and investigated.•The thermal characteristics of glasses are measured.•The crystallization process is studied.•The glass structural information is provided.•The contribution of photoluminescence of bismuth was found for the glass doped with 1% Bi.
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