共查询到20条相似文献,搜索用时 18 毫秒
1.
Roman Tomaschitz 《Physics letters. A》2008,372(24):4344-4349
Tachyonic spectral densities of ultra-relativistic electron populations are fitted to the γ-ray spectra of two TeV blazars, the BL Lacertae objects 1ES 0229+200 and 1ES 0347-121. The spectral maps are compared to Galactic TeV sources, the γ-ray binary LS 5039 and the supernova remnant W28. In contrast to TeV photons, the extragalactic tachyon flux is not attenuated by interaction with the cosmic background light; there is no absorption of tachyonic γ-rays via pair creation, as tachyons do not interact with infrared background photons. The curvature of the observed γ-ray spectra is intrinsic, caused by the Boltzmann factor of the electron densities, and reproduced by a tachyonic cascade fit. In particular, the curvature in the spectral map of the Galactic microquasar is more pronounced than of the two extragalactic γ-ray sources. Estimates of the thermodynamic parameters of the thermal or, in the case of supernova remnant W28, shock-heated nonthermal electron plasma generating the tachyon flux are obtained from the spectral fits. 相似文献
2.
A. N. Aleev V. A. Arefiev V. P. Balandin V. K. Berdyshev V. K. Birulev A. S. Chvyrov I. I. Evsikov T. S. Grigalashvili B. N. Gus'kov I. M. Ivanchenko et al. 《Czechoslovak Journal of Physics》1990,40(11):1216-1225
A signal of the-K+K– decays has been observed in neutron-hydrogen interactions at energies of 30–70 GeV in an experiment using the BIS-2 spectrometer. The longitudinal momentum spectrum in the forward region,x
F<0·1 atp
T<1 GeV/c, can be well described by a power law dependence (1–x
F)N withN=4·28±0·42. Thep
T
2
-spectrum has been parametrized by the exp(–Bp
T
2
) law with the exponentB=(3·02±0·55) (GeV/c)–2. The extrapolation of the measured cross section to the full kinematic region yields a value of (220±85) b in agreement with measurements from the proton beams. 相似文献
3.
B. P. Bannik S. Vokál V. A. Leskin K. D. Tolstov M. Šumbera V. I. Bubnov A. S. Gaitinov L. E. Eremenko B. Kusambaev I. J. Chasnikov M. Marku A. Marin M. Haiduc L. Achmadalieva M. Karabová J. Karaba V. Novický E. Síleš M. Tóthová V. G. Bogdanov N. A. Perfilov V. A. Plyushchev Z. I. Solovjeva M. I. Adamovich V. G. Larionova S. P. Kharlamov P. N. Lebedev E. S. Basova N. A. Bondarenko U. G. Guljamov R. M. Ibatov M. M. Muminov B. G. Rachimbajev G. M. Chernov A. I. Bondarenko K. G. Gulamov N. Dalkhazhav R. Togo B. Chadra V. A. Antonchik V. A. Bakaev S. D. Bogdanov V. I. Ostroumov 《Czechoslovak Journal of Physics》1981,31(5):490-498
In inelastic collisions of protons with photoemulsion nuclei at 4·5 GeV/c, data have been obtained on multiplicity of shower particles, energy spectrum of fast secondary protons with (2·5±0·1) GeV average energy, and energy spectrum of produced charged pions with (640±±50) MeV average energy. The multiplicity, angular distributions, and energy of particles arising from splitting target-nuclei are also determined: the proton spectrum is approximated by the power dependenceE
- with=1·4±0·1. The distribution of protons and-mesons over rapiditiesy=0·5 In[(E+p)/(E–p)] have been obtained. The average multiplicity for secondary particles coincide with the predicted values given by the cascade-evaporation model.Dedicated to the 25th anniversary of the Joint Institute for Nuclear Research.The authors would like to express their gratitude to the synchrophasotron group of JINR and to the group of S. J. Ljubomilov for the assistance in the experiment, to V. S. Barashenkov and V. V. Ivanov for the assistance in the cascade-evaporation model calculations, and also to the laboratories which took part in the scanning and measurement. 相似文献
4.
Cheng-Fu Yang Chia-Ching Wu Chean-Cheng Su Ying-Chung Chen 《Applied Physics A: Materials Science & Processing》2009,97(2):455-460
The relative permittivity of O-cresol Novolac epoxy resin/(Ba0.9Sr0.1)(Ti0.9Zr0.1)O3 (epoxy/BSTZ) composites with various contents of BSTZ ceramic powder was measured at 10 kHz to 1 MHz. As the content of BSTZ
ceramic powder increases from 0 to 70 wt%, the permittivity increases from 5.72 to 25.23. Four different mixing rules are
used to predict the variation of permittivity of epoxy/BSTZ composites, and the Lichtenecker equation fits the measured results.
The permittivity of epoxy/BSTZ composites slightly increases as the measured temperature increases, and is unchanged when
the measured temperatures are higher than the Curie temperature of BSTZ ceramic. This research proves that we can develop
the epoxy/BSTZ composites with characteristics of stable temperature and frequency dependence. 相似文献
5.
Chunxia LiangXinyong Li Zhenping QuMoses Tade Shaomin Liu 《Applied Surface Science》2012,258(8):3738-3743
UV-vis spectra, XRD, H2-TPR, TEM and ESR were used to characterize a series of Cu/γ-Al2O3 catalysts, which were prepared by incipient wetness impregnation using copper nitrate, copper acetate or copper sulfate as precursors, to study the role of Cu species on Cu/γ-Al2O3 catalysts for NH3-SCO reaction. It was found that the mixture of CuO phase and CuAl2O4 phase formed on various Cu/γ-Al2O3 catalysts, and the Cu species and dispersion had significant influence on the Cu/γ-Al2O3 activity. Highly dispersed CuO phase on the support would be related with its high activity for the NH3-SCO reaction. 相似文献
6.
The influence of hydrothermal modification of γ-Al2O3 on the properties of NiMo/γ-Al2O3 catalyst was investigated in this paper. The experimental results showed that the use of the modified γ-Al2O3 in the preparation of the NiMo/γ-Al2O3 catalyst led to the increase of the dispersion of the surface Mo and Ni oxides, favored the formation of the poly-molybdates and promoted the reduction of the active Mo oxides owing to the increase of the surface acidity of the modified γ-Al2O3. Therefore, the NiMo/γ-Al2O3 catalyst supported on the modified γ-Al2O3 exhibited a higher hydrodenitrogenation (HDN) activity than that supported on the untreated γ-Al2O3 in the temperature range of 300-340 °C. 相似文献
7.
Polycrystalline Pb1−x
Sr
x
(Fe0.012Ti0.988)O3 (0.2≤x≤0.4) (PSFT) thin films have been grown on fused quartz substrates by metallo-organic decomposition technique. The grown films
were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), source meter and UV–Vis–NIR spectrophotometer
to determine the structural, microstructural, dc resistivity and optical properties. The XRD pattern confirmed that the PSFT
films has distorted tetragonal single phase, which close to cubic at higher Sr concentration. AFM analysis revealed that the
grains size reduces with increasing Sr concentration and their average values lies in the range of 26–9 nm. The higher values
of dc resistivity of PSFT nano grains indicate that the transmission of light occurs within these grains up to short wavelength.
The refractive index and the extinction coefficient were determined from the optical transmission spectrum in the wavelength
range of 200–1100 nm and compared with that theoretically calculated, when fitted to a single oscillator model. The values
of optical band gap were determined from Tauc’s extrapolation fitting and suggests that the transformation of electrons during
transmission of light through local states within Fermi gap. 相似文献
8.
The extoic structure of 29P was investigated by measuring its magnetic moment in the ground state with β-NMR method. We got the experimental value of 1.2346 μN after diamagnetism correction. It is very close to the calculated value of 1.1009 μN computed with shell model. The shell model calculation also gave a proton density distribution of 29P with a long tail. The present results show that 2s1/2 proton in the 29P may lead to the proton-skin structure. 相似文献
9.
Yosun HwangS. Angappane Jongnam ParkKwangjin An T. HyeonJe-Geun Park 《Current Applied Physics》2012,12(3):808-811
We have carried out systematic studies on well-characterized monodisperse Fe3O4/γ-Fe2O3 core/shell nanoparticles of 2-30 nm having a very narrow size distribution and possessing a uniquely mono-layer of surface γ-Fe2O3. This unique core-shell structure, probably having a disordered magnetic surface state, leads us to three key observations of unusual magnetic properties: i) a very large magnetic exchange anisotropy reaching over 7 × 106 erg/cm3 for the smaller particles, ii) exchange bias behavior in the magnetization data of the core/shell Fe3O4/γ-Fe2O3 nanoparticles, and iii) the temperature dependence of the coercive field following an unusual exponential behavior. 相似文献
10.
D. Decamp B. Deschizeaux C. Goy J. -P. Lees M. -N. Minard R. Alemany J. M. Crespo M. Delfino E. Fernandez V. Gaitan et al. 《Zeitschrift fur Physik C Particles and Fields》1992,54(1):75-85
This paper describes a study of Bose-Einstein correlations made using the ALEPH detector at LEP. The correlations are found to enhance the two particle differential cross section for pairs of identical pions by a factor which can be roughly parametrized byR(Q)=1+ exp(-Q22), whereQ is the difference in the 3-momenta of the two pions in their centre of mass frame, =0.51±0.04±0.11 and =3.3±0.2±0.8 GeV–1, which corresponds to a source size of 0.65±0.04±0.16 fm. The large systematic errors on these results reflect their strong dependence on the choice of the reference sample used in the analysis. This problem is believed to occur primarily because of uncertainties in the rates of resonance production and a lack of knowledge about the pion-pion strong interaction. No significant correlations are seen amongst like-charged pion-kaon pairs.Supported by CAICYT, Spain 相似文献
11.
Mireya Castillo 《International Journal of Infrared and Millimeter Waves》1992,13(6):909-922
A FT-IR spectroscopic study was carried out in the region 4000–400 cm–1 for ZnSeNi and ZnSNi at room temperature. The data obtained were examined on the basis of the energy states calculations of the (3d)n configuration, based on the defect molecule approach. The present investigation reveals the transition from the ground state to the first two excited states namely3T1–3A2 and3T1–3T2 of Ni+2 (d8). 相似文献
12.
Zhongzhu Wang Hong Bi Jian Liu Tao Sun Xianliang Wu 《Journal of magnetism and magnetic materials》2008
The conducting protonated polyaniline (ES)/γ-Fe2O3 nanocomposite with the different γ-Fe2O3 content were synthesized by in-situ polymerization. Its morphology, microstructure, DC conductivity and magnetic properties of samples were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), four-wire-technique, and vibrating sample magnetometer (VSM), respectively. The microwave absorbing properties of the nanocomposite powders dispersing in wax coating with the coating thickness of 2 mm were investigated using a vector network analyzers in the frequency range of 7–18 GHz. The pure ES has shown the absorption band with a maximum absorption at approximately 16 GHz and a width (defined as frequency difference between points where the absorption is more than 8 dB) of 3.24 GHz, when 10% γ-Fe2O3 by weight is incorporated , the width is broadened to 4.13 GHz and some other absorption bands appear in the range of 7–13 GHz. The parameter dielectric loss tan δe (=ε″/ε′) in the 7–18 GHz is found to decrease with increasing γ-Fe2O3 contents with 10%, 20%, 30%, respectively, but magnetic loss tan δm (=μ″/μ′) increases with increasing γ-Fe2O3 contents. The results show that moderate content of γ-Fe2O3 nanoparticles embedded in protonated polyaniline matrix may create advanced microwave absorption properties due to simultaneous adjusting of dielectric loss and magnetic loss. 相似文献
13.
14.
C. Guo L. Luan X. Ding F. Zhang F. G. Shi F. Gao L. Liang 《Applied physics. B, Lasers and optics》2009,95(4):779-785
Eu2+ and Mn2+ co-activated Sr5(PO4)3Cl phosphors with blue and orange color double emission bands, under a broad-band excitation wavelength range of 340–400 nm,
were synthesized by the solid-state reaction. It was found that the processing parameters, including the fluxes, annealing
time and activators concentrations, affect the emission intensity and other luminescent properties. Energy transfer between
Eu2+ and Mn2+ was discovered and the transfer efficiency was also estimated based on relative intensities of Eu2+ and Mn2+ emission. Thus the relative strength of blue and orange emission intensities could be tuned by varying the relative concentration
of Eu2+ and Mn2+. Since the photoluminescence excitation spectra of the newly developed Sr5(PO4)3Cl:Eu2+, Mn2+ phosphors exhibit a strong absorption in the range of 340–400 nm, they are promising for producing UV-LED-based white LEDs. 相似文献
15.
Bilsen Tural ?. Betül Sopac? Ayhan S. Demir Mürvet Volkan 《Journal of Physics and Chemistry of Solids》2011,72(8):968-973
γ-Fe2O3 (maghemite)-silica nanocomposite particles were synthesized using a sol-gel method. The condensation products of 3-glycidoxy propyltrimethoxy silane (GPTMS) and nitrilotriacetic acid (NTA) were introduced onto the surfaces of the γ-Fe2O3-silica nanocomposite particles and subsequently, these modified surfaces were complexed with cobalt (Co+2) metal ions. A possibility of using these surface modified γ-Fe2O3-silica particles for the purification of 6×histidine tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) based on magnetic separation was investigated. X-ray diffraction (XRD), thermal analysis, and vibrating sample magnetometry (VSM) methods were used to characterize the surface modified superparamagnetic γ-Fe2O3 (maghemite)-silica nanoparticles. XRD (Scherer's equation) results indicate that the primary particle size of maghemite was around 11 nm. Magnetic characterization results confirmed that the γ-Fe2O3 (maghemite)-silica nanoparticles were superparamagnetic. According to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results, these superparamagnetic nanoparticles specifically capture 6×His-tagged BAL from crude extract of Escherichia coli (E. coli) BL21(DE3)pLysS/BALHIS. This study shows that the surface modified γ-Fe2O3 (maghemite)-silica nanoparticles are eligible for immobilized metal-ion affinity adsorption for histidine tagged recombinant proteins with its high capacity (3.16±0.4 mg/g) and selectivity. 相似文献
16.
17.
Previous experimental results of (EC+β+) decay for the medium-heavy nuclei reported by our group since 1996, including 153Er, 157Yb, 209Fr, 128Ce, 130Ce, and 128Pr have been briefly summarized. The observed low-lying states in their daughter nuclei have been reviewed in a systematic way and compared with different model calculations. Finally, some questions have been put forward for further study and discussion. 相似文献
18.
《Physics letters. [Part B]》1988,215(1):199-204
Data from the reaction K−p→K−K+Λ at 11 GeV/c have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moments analysis of the K−K+ system provides evidence for a rather narrow JPC=4++ state at ∼2.2 GeV/c2. Relevant data from the reaction K−p→K0sK0sΛ in the present experiment are shown also, and comparisons made to results from MARK III and GAMS in this mass region. 相似文献
19.
Jianhong Peng Mirabbos Hojamberdiev Baowei Cao Juan Wang Yunhua Xu 《Applied Physics A: Materials Science & Processing》2011,103(2):511-516
Submicron BiFeO3 powders were successfully synthesized via a simple hydrothermal process with the assistance of mineralizer (NaOH) at 150–190°C,
using FeCl3 and Bi(NO3)3⋅5H2O as reactants. The effects of mineralizer concentration, reaction temperature and time on the phase evolution and crystal
morphology of the resulting samples were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry
and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) were used to characterize the as-synthesized
samples. The experimental results revealed that a pure BiFeO3 phase could be formed at a temperature ranging from 170 to 190°C for 4–20 h in the presence of 0.03–0.12 M NaOH. It was found
that the mineralizer concentration, reaction temperature and time played a key role in controlling the growing speed of nuclei
and formation of BiFeO3 crystallites. The possible formation mechanisms of submicron BiFeO3 powders with different morphologies were presented. The magnetization of BiFeO3 powders showed a weak ferromagnetic behavior at room temperature. 相似文献
20.
The extended stretch-bender Hamiltonian, incorporating spin-orbit coupling and overall rotation, has been used to calculate the spin-vibronic structure of the X?2B1 state of NH2 up to the barrier to linearity of this state. A detailed comparison has been made with experimental measurements of these rovibronic states, the majority of which are due to Vervloet and his collaborators. We have shown that, in order to fit the variation of the vibronic spin-orbit coupling constant over the whole of this energy regime, the effective linear molecule spin-orbit coupling constant, ASO, must be increased from the earlier value of 50 cm−1 of Ch. Jungen, K.-E. J. Hallin, and A. Merer (Mol. Phys.40, 65-94 (1980)) to 61.6 cm−1. Evidence has also been provided for the large quenching of the spin-orbit coupling as the molecule bends, reflected in the large valuee of gK=6 cm−1. The pattern of calculated spinrovibronic levels, including the effects of spin uncoupling, is in good agreement with that measured experimentally. 相似文献