共查询到20条相似文献,搜索用时 62 毫秒
1.
Taszner A. Kowalski A. Heldt J. 《Applied Physics A: Materials Science & Processing》1976,11(2):203-205
The decay rate of2
D
5/2 level of Cd II has been measured by the magnetic-field power-dip method. The decay rate at the zero-pressure limit is found
to be 2.4·106s−1. The calculated collision cross section for excited Cd ions with He atoms equals 0.91·10−15 cm2.
This work was supported by the Institute of Quantum Electronics. WAT Warszawa, within the project 06.2.3. 相似文献
2.
K. R. Allakhverdiev M. Ö. Yetis T. K. Baykara S. M. T. Özbek E. Yu. Salaev 《Laser Physics》2011,21(3):598-600
Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described
and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra
(400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear
materials of GaSe
x
S1 − x
(0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding
to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working
or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation
of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3
ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10−4−1 × 10−4 W/cm2) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10−4−1.5 × 10−4 W/cm2) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10−4–4.6 × 10−4 W/cm2) at 1360 nm. Threshold damage density is more than 10 MW/cm2 at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators. 相似文献
3.
O. Cozar I. Ardelean V. Simon L. David N. Vedean V. Mih 《Applied magnetic resonance》1999,16(4):473-480
Two lead-phosphate glass systems doped with both copper and vanadium ions in different ratios were studied by EPR (electron paramagnetic resonance) method. EPR spectra and parameters (g‖ = 2.44, g⊥ = 2.08 andA ‖ = 117.6 · 10−4 cm−1) obtained for x(CuO · V2O5)(l−x)[2P2O5 · PbO] glasses withx ≤ 10 mol% suggest a tetrahedral (Td) coordination of Cu2+ ions and not a tetragonally elongated octahedron as has been assumed in previous works. The ground state of the paramagnetic electron is thed xy copper orbital with a 4pz contribution of 6%. For 20 ≤x ≤ 40 mol% a broad line (ΔB = 307 G) characteristic for clustered ions appears atg = 2.18. The V4+ ions are evidenced only in the spectra of x(CuO · 2V2O5)(1 −x)[2P2O5 · PbO] glasses and the resonance parameters suggest a pentacoordinated C4v local symmetry for these ions. The hyperfine structures characteristic for Cu2+ and V4+ ions disappear for 10 ≤x ≤ 40 mol% due to the mixed exchange Cu2+−V4+ pair formation in these glasses. 相似文献
4.
V. V. Naumov O. A. Grebenshchikov V. B. Zalesskii 《Journal of Applied Spectroscopy》2006,73(5):753-759
We describe a method for automated measurement of the integrated sensitivity of solar cells (SCs) and multielement photoconverters
(MPCs) using an experimental apparatus including a Pentium III personal computer (PC), an HP-34401A digital multimeter (DM),
a stabilized radiation source (SRS), a controllable focusing system, an X-Y positioning device based on CD-RW optical disk
storage devices.
The method provides high accuracy in measuring the size of photosensitive areas of the solar cells and multielement photoconverters
and inhomogeneities in their active regions, which makes it possible to correct the production process in the development
stage and during fabrication of test prototypes for the solar cells and multielement photoconverters.
The radiation power from the stabilized radiation source was ≤1 W; the ranges of the scanning steps along the X, Y coordinates
were 10–100 μm, the range of the transverse cross sectional diameters of the focused radiation beam was 10–100 μm, the measurable
photocurrents were 10−9 A to 2 A; scanning rate along the X, Y coordinates, ≤100 mm/sec; relative mean-square error (RMSE) for measurement of the
integrated sensitivity of the solar cells, 0.2 ≤ γS
int
≤ 0.9% in the ranges of measurable photocurrents 1 mA ≤ Iph ≤ 750 mA and areas 0.1 ≤ A ≤ 25 cm2 for number of measurements equal to ≤ 2· 105; instability of the radiation power (luminosity) ≤ 0.08% for 1 h or ≤ 0.4% for 8 h continuous operation; stabilized power
range for the stabilized radiation source, 10−2–102 W. The software was written in Delphi 7.0.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 670–675, September–October, 2006. 相似文献
5.
《Il Nuovo Cimento C》1991,14(2):171-193
Summary The data recorded with the neutrino detectors at Mont Blanc, Kamioka, Baksan and with the gravitational-wave detectors in
Maryland and Rome have been analysed searching for correlations associated with SN 1987 A, without presuming or excluding
hypotheses for correlations due to neutrinos and gravitational waves. The statistical analysis has been based on a previous
analysis that showed a correlation among Maryland, Rome and Mont Blanc with a probability to be accidental less than 10−5. Independent correlations are found during a period of one or two hours, around the Mont Blanc 5ν burst (2h 52 min 36 s UT),
among the various sets of data: Mont Blanc-Baksan with a probability to be accidental of the order ofp∼4·10−3, Mont Blanc-Kamioka withp∼4·10−3, Maryland-Rome-Kamioka withp∼5·10−4, Maryland-Rome-Baksan withp∼5·10−2. It is remarkable that the events from all the neutrino detectors follow the signals from the g.w. detectors by a time of
the order of 1/2 or 1 s. At present we will not give a physical interpretation of the observed correlations which have strong
statistical significance.
Professor Edoardo Amaldi died on December 5, 1989. 相似文献
6.
ZEUS Collaboration M. Derrick D. Krakauer S. Magill D. Mikunas B. Musgrave J. Repond R. Stanek R. L. Talaga H. Zhang et al. 《Zeitschrift fur Physik C Particles and Fields》1995,69(1):607-620
We report on a measurement of the proton structure functionF
2 in the range 3.5×10−5≤x≤4×10−3 and 1.5 GeV2≤Q
2≤15GeV2 at theep collider HERA operating at a centre-of-mass energy of √s=300GeV. The rise ofF
2 with decreasingx observed in the previous HERA measurements persists in this lowerx andQ
2 range. TheQ
2 evolution ofF
2, even at the lowestQ
2 andx measured, is consistent with perturbative QCD.
supported by EU HCM contract ERB-CHRX-CT93-0376 相似文献
7.
M. Aglietta B. Alessandro P. Antonioli F. Arneodo L. Bergamasco A. Campos Fauth C. Castagnoli A. Castellina C. Cattadori A. Chiavassa et al. 《Il Nuovo Cimento C》1992,15(4):441-446
Summary A search for cosmic gamma-ray bursts in the GeV energy range has been performed by means of the EAS-TOP Extensive Air Shower
array at Campo Imperatore (Gran Sasso Laboratories) during the period March–December 1990. In 2566.5 hours of measurement
the obtained upper limit to the rate of bursts of amplitude >2% of the cosmic-ray intensity and time duration τ=1 s, isR≤7.9y−1 (90% c.l.). Assuming for γ-rays a differential energy spectrumS(E
0
)≈E
0
−2.5
, the corresponding upper limit to the energy flux of γ-rays with energy >5 GeV in bursts of duration τ≤1 s is Φ<8.3·10−5erg cm−2. 相似文献
8.
The field dependence of the nuclear spin-lattice relaxation (SLR) of cold implanted 82Br (T ≤ 25 mK) in α-Fe single crystals was investigated with nuclear magnetic resonance of oriented nuclei (NMR/ON) at low temperatures
as experimental technique. The SLR at the lattice sites with the hyperfine fields found by earlier NMR/ON experiments was
measured as a function of the applied external magnetic field B
ext parallel to the three principle axes [100], [110] and [111] of the iron single crystal. The data were evaluated with the
full relaxation formalism in the single impurity limit and for comparison also with the often employed model of a single exponential function with an effective relaxation time
T
1′. With a phenomenological model the high field values of the relaxation rates r
∞, [100]′ = 6.6(2) · 10−15 T2sK−1, r
∞, [110] = 5.4(2) · 10−15 T2sK−1 and r
∞, [111] = 5.2(1) · 10−15 T2sK−1 were obtained. 相似文献
9.
F. J. M. Farley 《Zeitschrift fur Physik C Particles and Fields》1992,56(Z1):S88-S96
Measurements of the anomalous magnetic moment of the muon are reviewed. The emphasis is put on the first one of a series of
three CERN experiments which led to an experimental value ofa=1165922.9 (8.5)·10−9 (±7.2ppm), and which compares well with the present theoretical resulta=1165919.2 (1.8)·10−9 (±1.5ppm). 相似文献
10.
A. V. Voitsekhovskii A. G. Korotaev A. P. Kokhanenko D. V. Grigor’ev V. S. Varavin S. A. Dvoretskii Yu. G. Sidorov N. N. Mikhailov N. Kh. Talipov 《Russian Physics Journal》2006,49(9):929-933
The dynamics of accumulation of electrically active radiation defects under ion doping of epitaxial Cd
x
Hg
1−x
Te films is studied for various distributions of film composition in the implantation region. The epitaxial films were irradiated
by boron ions at room temperature in the continuous regime, with the dose ranging within 1011−3·1015 cm−2, energy — 20–150 keV, and ion current density — j = 0.001–0.2 μA·cm−2. It is found that the natural logarithm of the introduction rate of electrically active radiation defects linearly depends
on the epitaxial-film composition in the range of mean projected path of implanted ions. An analysis of the experimental data
shows that the dynamics of accumulation of electrically active radiation defects is determined by the epitaxial-film composition
in the implantation region.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 25–28, September, 2006. 相似文献
11.
M. A. Sheremet 《Thermophysics and Aeromechanics》2011,18(3):447-458
The mathematical modelling of unsteady regimes of natural convection in a closed cylindrical region with a heat-conducting
shell of finite thickness was carried out in the presence of a local heat source under the conditions of convective heat exchange
with the ambient medium. The mathematical model was constructed in dimensionless variables “stream function — vorticity vector
— temperature” in the cylindrical coordinate system. The influence of the Rayleigh number, 104 ≤ Ra ≤ 106, of the unsteadiness factor 0 < τ < 300, of the thermal conductivity ratio λ
2,1 = 5.7·10−4, 4.3·10−2, and the energy source sizes on both local characteristics (streamlines and temperature fields) and on the integral complex
(the mean Nusselt number on typical boundaries) was analysed in detail. Thermohydrodynamic peculiarities due to the geometry
of the object of research were established. 相似文献
12.
E. Amaldi C. Cosmelli G. V. Pallottino G. Pizzella P. Rapagnani F. Ricci P. Bonifazi M. G. Castellano P. Carelli V. Foglietti G. Cavallari E. Coccia I. Modena R. Habel 《Il Nuovo Cimento C》1986,9(4):829-845
Summary In November 1985 the gravitational-wave antenna of the Rome group, installed at CERN, has started operating. It consists of
a 5056 aluminium cilinder 3 m long, 2270 kg heavy, cooled at 4.2 K. The antenna vibrations are detected by means of a resonant
capacitive transducer that together with the bar makes a two-coupled-oscillator system. The low-noise amplification is obtained
with a d.c. SQUID amplifier. The frequencies of the two resonant modes are:v
-=907.116 Hz andv
+=923.083 Hz, with merit factorsQ
−=3.2·106 andQ
+=5.6·106. The sensitivity to short gravitational bursts, expressed in terms of effective noise temperature, is 18 mK. This corresponds
to a change in the metric tensor whose Fourier transform isH=1.1·10−21 Hz−1. For monochromatic waves the antenna is sensitive (SNR=1) toh∼2·10−25 in a band width of about 1/3 Hz, with a three months integration time.
Riassunto Nel novembre 1985 è stata messa in funzione l'antenna gravitazionale del gruppo di Roma, installata al CERN. Questa consiste di un cilindro d'alluminio 5056 lungo 3 m e pesante 2270 kg, raffeeddato a 4.2 K. Le vibrazioni dell'antenna vengono rivelate mediante un transduttore capacitivo risonante, che assieme alla sbarra forma un sistema di due oscillatori accoppiati. L'amplificazione a basso rumore è ottenuta con un amplificatore a d.c.-SQUID. Le frequenze dei due modi risonanti sono:v -=907.116 Hz ev +=923.083 Hz, con fattori di meritoQ −=3.2·106 eQ + =5.6·106. La sensibilità per brevi fiotti di onde gravitazionali, espressa in termini di temperatura efficace di numore, è 18 mK. Questa corrisponde a una variazione di tensore metrico con trasformata di Fourier:H=1.1·10−21 Hz. Per le onde monocromatiche l'antenna è sensibile (SNR=1) ah∼2·10−25 in una banda di circa 1/3 Hz, con tempo d'integrazione di tre mesi.相似文献
13.
R. Brazis L. Safonova R. Narkowicz 《International Journal of Infrared and Millimeter Waves》1997,18(8):1575-1584
Non-transmission bands of electromagnetic waves propagating along the layers in periodic structures are studied in the steady
magnetic field perpendicular both to the uniaxis and the direction of propagation. The band control range (36÷75 GHz) inn-InSb/Al2O3 structures with the carrier densities 4 1013 ≤n ≤ 8 1014 cm−3 in magnetic fieldsB
o ≤ 2 T at temperatures 77 ≤T ≤ 200 K is found to agree with the calculated in the effective medium approximation. Attenuation down to −50 dB within the
band is observed. The band lineshape is found to indicate additional effects related to the finite layer thickness and periodicity
termination predicted by a more rigorous theory of dispersion. 相似文献
14.
Summary Suspensions of purple-membrane fragments from Halobacterium halobium were oriented by a static electric field with intensity
up to 25V/cm in the range ofpH from 4 to 9. It was found that the orientation of the transient dipole moment of the retinal chromophore for what concerns
the permanent dipole moment of the membrane fragment undergoes a transition from (60±1)° atpH 5 to (71±1)° atpH 6. Moreover, the permanent dipole moment of the membrane fragments of 1.8·10−23 C·m found at thepH values from 4 to 7 reduces to 1.3·10−23
C·m atpH higher than 7.
Riassunto Sospensioni di frammenti di membrana purpurea del Halobacterium halobium apH fra 4 e 9 furono orientati da un campo elettrico statico d’intensità fino a 25 V/cm. Fu trovato che l’orientazione del momento di transizione di dipolo del cromoforo, il retinale, rispetto al momento di dipolo permanente dei frammenti di membrana subisce una variazione da (60±1)°apH 5 a (71±1)° apH 6. Inoltre, il momento di dipolo permanente dei frammenti di membrana di 1.8·10−23C·m trovato nell’intervallo dipH da 4 a 7 si riduce a 1.3·10−23C·m per valori dipH delle sospensioni maggiori di 7.相似文献
15.
G. G. Vertogradov V. P. Uryadov V. G. Vertogradov 《Radiophysics and Quantum Electronics》2007,50(1):1-7
We present the results of the ionosphere oblique chirp sounding on the Cyprus—Nizhny Novgorod, Cyprus—Rostov-on-Don, and Moscow—Rostov-on-Don
mid-latitude paths during X-ray flares in January 17, 19, and 20, 2005. It is found that during strong flares the blackout
of short radio waves was observed over the entire frequency range of chirp sounding on the Cyprus—Nizhny Novgorod and Cyprus—Rostov-on-Don
paths. Modeling of the electron-density profiles in the lower ionosphere based on absorption of short radio waves on the Moscow—Rostov-on-Don
path at different stages of the decay of the X-ray radiation intensity is carried out. It is shown that at the instant corresponding
to the maximum value of the flare radiation flux, the electron density in the lower ionosphere at altitudes 60–80 km increased
by a factor of about 10 and 100 for flares with radiation flux densities 5·10−2 and 3·10−1
erg/(cm
2·s) in the wavelength range 0.5–4.0 Å which took place in January 19 and 20, respectively.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 1, pp. 1–8, January 2007. 相似文献
16.
Ganesh Prasad Yogesh Prasad G. S. Gusain Manjari Badoni J. M. S. Rana R. C. Ramola 《Indian Journal of Physics》2009,83(6):887-892
Radon was measured in soil-gas and groundwater in the Budhakedar area of Tehri Garhwal, India in summer and winter to obtain
the seasonal variation and its correlation with radon exhalation rate. The environmental surface gamma dose rate was also
measured in the same area. The radon exhalation rate in the soil sample collected from different geological unit of Budhakedar
area was measured using plastic track detector (LR-115 type II) technique. The variation in the radon concentration in soil-gas
was found to vary from 1098 to 31,776 Bq.m−3 with an average of 7456 Bq.m−3 in summer season and 3501 to 42883 Bq.m−3 with an average of 17148 Bq.m−3 in winter season. In groundwater, it was found to vary from 8 to 3047 Bq.l−1 with an average value 510 Bq.l−1 in summer and 26 to 2311 Bq.l−1 with an average value 433 Bq.L−1 in winter. Surface gamma dose rate in the study area varied from 32.4 to 83.6 μR.h−1 with an overall mean of 58.7 μ-R.h−1 in summer and 34.6 to 79.3 μR.h−1 with an average value 58.2 μR.h−1 in winter. Radon exhalation rate from collected soil samples was found to vary from 0.1 × 10−5 to 5.7 × 10−5 Bq.kg−1.h−1 with an average of 1.5 × 10−5 Bq.kg−1.h−1 in summer season and 1.7 × 10−5 to 9.6 × 10−5 Bq.kg−1.h−1 with an average of 5.5 × 10−5 Bq.kg−1.h−1. A weak negative correlation was observed between radon exhalation rate from soil and radon concentration in the soil. Radon
exhalation rate from the soil was also not found to be correlated with the gamma dose rate, while it shows a positive correlation
with radon concentration in water in summer season. Inter-correlations among various parameters are discussed in detail.
相似文献
17.
We used the spin-Hamiltonian method for the analysis of the electron paramagnetic resonance (EPR) spectrum of Fe3+ as a probe ion in (NH4)2AlF5·H2O single crystalline basic material. The theoretical expressions for the magnetic field (at which the fine structure transition lines appear) versus the angle between the magnetic field and the axis of symmetry of the magnetic complex are also given. These values were calculated by applying the perturbation theory to the second-order terms. From the experimental results (at 300 K and 9.21 GHz), the spin-Hamiltonian parameters were deduced:D=(668±10)·10−4 T,E=(−56±10)·10−4 T,a=(−54±10)·10−4 T,F=(30±10)·10−4 T. An isotropic superhyperfine structure was evidenced for the five fluorine ions. The obtained EPR data were used to determine the local symmetry of the Al3+ ion. A good agreement with X-ray diffraction measurements was found. 相似文献
18.
A large stack of lead-emulsion sandwich detector assembly was flown over Hyderabad, India. High energy gamma rays at the float
altitude were unambiguously identified from the cascades they induced, and their energies reliably determined by improved
methods. From an analysis of 163 gamma rays of energy ≳ 30 GeV, it is found that the differential energy spectrum is represented
by the power lawJ
r
(E)= 129·4E
−2·62±0·12 photons m−2 sr−1sec−1 GeV−1 at an effective atmospheric depth of 14·3 g cm−2; this is the first reliable balloon measurement of atmospheric gamma rays in the energy range 40–1000 GeV. After correcting
for the gamma rays radiated by the primary cosmic ray electrons, the production spectrum of gamma rays, resulting from the
collisions of cosmic ray nuclei with air nuclei, at the top of the atmosphere isP
r
(E, 0)=8·2 × 10−4 E2.60±0.09 photons g−1sr−1sec−1 GeV−1. The atmospheric propagation of the electromagnetic component due to the cascade process is also derived from the gamma ray
production spectrum. 相似文献
19.
I. G. Gogidze P. B. Kuminov A. V. Sergeev A. I. Elant’ev E. M. Men’shchikov E. M. Gershenzon 《Technical Physics》1998,43(10):1193-1198
A new type of fast detector is proposed. The operation of the detector is based on the change induced in the kinetic inductance
of NbN and YBa2Cu3O7−δ
superconducting films by nonequilibrium quasiparticles produced by electromagnetic radiation. The speed of a NbN detector
is essentially temperature-independent and is less than 1 ps. A model based on the Omen-Scalapino scheme describes well the
experimental dependence of the voltage-power sensitivity of a NbN detector on the modulation frequency of the radiation. A
low equilibrium quasiparticle density and a high quantum yield give detecting power D*=1012W−1 · cm · Hz1/2 at temperature T=4.2 K and D*=1016 W−1 · cm · Hz1/2 at temperature T=1.6 K. The time constant of the low-temperature YBaCuO induction detector is determined only by the electron-phonon interaction
time τ
e-ph
d
in the nodal regions.
Zh. Tekh. Fiz. 68, 63–69 (October 1998) 相似文献
20.
A. V. Voitsekhovskii D. V. Grigoryev V. A. Yuryev S. N. Nesmelov 《Russian Physics Journal》2007,50(12):1218-1225
The thermal parameters of a SiGe microbolometer were calculated using numerical modeling. The calculated thermal conduction and thermal response time are
in good agreement with the values found experimentally and range between 2·10−7 and 7·10−8 W/K and 1.5 and 4.5 ms, respectively. High sensitivity of microbolometer is achieved due to optimization of the thermal response
time and thermal conduction by fitting the geometry of supporting heat-removing legs or by selection of a suitable material
providing boundary thermal resistance higher than 8·10−3 cm2·K/W at the SiGe interface.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 44–50, December, 2007. 相似文献