共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
P. Rapagnani 《Il Nuovo Cimento C》1982,5(4):385-408
Summary The characteristics of a new capacitive resonant transducer developed and tested on a small (M=11.2 kg) cryogenic gravitational-wave antenna at the liquid helium temperature are presented. The resonator frequency can
be tuned within 0.1 Hz of the antenna frequency. The system has a mechanical merit factorQ≃5·105 and a ratio between the electrical energy in the transducer and the energy in the antenna β=3·10−3 atT=4.2 K. With these parameters, the transducer allows one to reach an effective noise temperatureT
eff≃60 mK using a cooled FET preamplifier, and, if coupled to a r.f.-SQUID, allows one to reachT
eff≃10 mK for the 5000 kg cryogenic gravitational-wave antenna of the Roma group at CERN (Geneva).
Riassunto Si presentano le caratteristiche di un nuovo trasduttore risonante di tipo capacitivo. Il trasduttore è stato provato su una piccola antenna di 11.2 kg di massa, raffreddata alla temperature dell'elio liquido. La frequenza del risuonatore è stata accordata entro 0.1 Hz della frequenza dell'antenna. A 4.2 K, il sistema ha un fattore di merito meccanicoQ≃5·105 ed il rapporto tra l'energia elettrica nel trasduttore e l'energia nell'antenna è β=3·10−3. Con i valori dei parametri ottenuti, il trasduttore permette di raggiungere una temperatura efficace di rumoreT eff≃60 mK usando un amplificatore a FET raffreddato e, se accoppiato ad un r.f.-SQUID, consente di avereT eff≃10 mK per l'antenna gravitazionale criogenica di 5000 kg del gruppo di Roma, in funzione presso il CERN (Ginevra).相似文献
3.
N. Hashimoto T.R. Saitoh G. Sletten R.A. Bark M. Bergström K. Furuno T. Komatsubara T. Shizuma S. Törmänen P.G. Varmette 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):327-330
Abstact: High-spin states in 183Re have been studied using the 176Yb(11B,4n) reaction at 52 and 57 MeV. Two high-K bands have been observed directly by a time-correlated γ-γ coincidence measurement. One of the bands is built on an isomeric
K
π=(25/2)+ state at E
x= 1908 keV with a half-life of 0.82(2) ms. The other band, assigned as K
π=(29/2)− at E
x= 2739 keV, decays to the (25/2)+ band. These bands are interpreted as three-quasiparticle structures, π(5/2)+[402] &⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (25/2)+ band and π(9/2)−[514] ⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (29/2)− band. The K
π= (29/2)− band becomes strongly Coriolis mixed with increasing spin and is gradually changing into a low-K s-band structure.
Received: 20 April 1998 相似文献
4.
A. A. Sorokin G. K. Ryasny B. A. Komissarova L. N. Fomicheva A. V. Tsvyashchenko S. M. Nikitin 《Hyperfine Interactions》2006,171(1-3):269-275
The perturbed angular correlation (PAC) measurements with the 111In-111Cd nuclear probe embedded into the lattice of the cubic (C15) Laves compound ZrZn2 showed that 111Cd nuclei experienced an axially symmetric electric quadrupole interaction with a frequency ν
Q
= 132.4 MHz at room temperature. The samples were synthesized and doped with the probe at a pressure 8 GPa. The temperature
dependence of ν
Q
was shown to be linear: ν
Q
(T) = 147(1 − 0.033 T) MHz. Since the value of ν
Q
is very close to that known for 111Cd in the lattice of Zn, we have checked if it could be assigned to residual Zn metal in the sample. For the Zn sample melted
and doped with 111In at 8 GPa we have obtained ν
Q
= 117.3 MHz at 300 K and 127 MHz at 80 K – both values considerably lower than that for 111In doped Zn samples prepared at an ambient pressure. These data, and the fact that ν
Q
(T) in Zn is known to follow the T
3/2 law, allow to attribute the ν
Q
value quoted above to 111Cd nuclei at the substitutional sites with tetrahedral symmetry in the Zn sublattice of ZrZn2. 相似文献
5.
《Physics of Atomic Nuclei》2004,67(6):1161-1171
The present status of the Baikal Neutrino Experiment and the present results of a search for upward going atmospheric neutrinos,
WIMPs, and magnetic monopoles obtained with the NT-200 detector are reviewed. The results of a search for very high-energy
neutrinos are presented as well. An upper limit on the ν
e
+ν
e
+ν
τ
neutrino diffuse flux of E
2Φ(E)<1.3×10−6 cm−2 s−1 sr−1 GeV within a neutrino energy range of 104–107 GeV is obtained, assumingan E
−2 behavior of the neutrino spectrum and a flavor ratio ν
e
:ν
π
:ν
τ
=1:1:1. We also describe the moderate upgrade of the NT-200 planned for the next few years and present a possible detector
on the Gigaton scale.
From Yadernaya Fizika, Vol. 67, No. 6, 2004, pp. 1186–1194.
Original English Text Copyright ? 2004 by Aynutdinov, Balkanov, Belolaptikov, Bezrukov, Budnev, Chensky, Chernov, Danilchenko,
Dzhilkibaev, Domogatsky, Dyachok, Gaponenko, O. Gress, T. Gress, Klabukov, Klimov, Klimushin, Konischev, Koshechkin, Kulepov,
Kuzmichev, Kuznetzov, Lubsandorzhiev, Mikheyev, Milenin, Mirgazov, Moiseiko, Osipova, Panfilov, G. Pan'kov, L. Pan'kov, Parfenov,
Pavlov, Pliskovsky, Pokhil, Polecshuk, Popova, Prosin, Rosanov, Rubtzov, Semeney, Shaibonov, Spiering, Streicher, Tarashansky,
Vasiliev, Vyatchin, Wischnewski, Yashin, Zhukov.
This article was submitted by the authors in English. 相似文献
6.
Summary The data of 46 months of the GEOGRAV gravitational-wave antenna are analysed to search for monochromatic Doppler-shifted signals
from rotating neutron stars, in the frequency band (856.2÷859.2) Hz. Two different methods were used. With the first, the
gravitational radiation from the whole sky is investigated and a limit ofh≤1·10−21 is found. With the second method only the radiation from a single source is searched. The Galactic Centre and the Large Magellanic
Cloud are considered as sources and the limit ofh≤6·10−22 is found. 相似文献
7.
The third-order elastic constants of single crystal GaSb are determined using ultrasonic pulse interferometer at 10 MHz. The
constants at 300°K, in units of 1011 N.m.−2, are Cl11 = ™ 4 ·75 ± 0·06 C144 = + 0·50 ± 0·25 C113 = ™ 3 ·08 ± 0·02 C166 = ™ 2·16 ± 0·13 C123 = ™ 0 ·44 ± 0·29 C456 = ™ 0·25 ± 0·15 These constants are used to evaluate the three anharmonic first and second neighbour force constants based
on modified Keating’s model. The constants are (in units of 1011 N.m−2)γ=− 2·406;δ=0·407;ε=−0·222. 相似文献
8.
G. Fabritius G. Flik J. Golczewski D. Herlach G. Jünemann M. Krenke K. Maier A. P. Pathak H. Rempp A. Seeger W. Sigle E. Widmann D. W. Cooke 《Hyperfine Interactions》1986,31(1-4):229-234
By means of π+/μ+ channelling, positive pions (π+) implanted intoTa, Mo, andW are investigated up to high temperatures. A striking observation is that the channelling effect disappears in a rather narrow
temperature interval centred at 0.26 (Ta) to 0.51 (W) of the melting temperature. From studies of π+ trapping by oxygen atoms inTa estimates for the low-temperature π+ diffusivity inTa [D
π(23K)=1.4·10−10±0.3 m2s−1,D
π(47K)=5.7·10−10±0.3 m2s−1] as well as for the binding enthalpy of π+ to 0 atoms (H
B=7·10−2 eV) have been obtained. The diffusion data are in reasonable agreement with the theory of phonon-assisted tunnelling. 相似文献
9.
A. T. Pugachev N. P. Churakova N. I. Gorbenko Kh. Saadli E. S. Syrkin 《Journal of Experimental and Theoretical Physics》1998,87(5):1014-1018
The thermal expansion coefficient a and structure of C60 films with thickness t∼3–10 nm were investigated in the temperature interval from room to liquid-nitrogen temperature by electron-optical methods.
The thermal expansion coefficient was determined from the temperature shift of the diffraction maxima in the electron diffraction
patterns. The objects of investigation were epitaxial C60 films condensed in vacuum on a (100) NaCl cleavage surface and oriented in the (111) plane. A surface-induced size effect
in the thermal expansion coefficient was observed. It was established that as t decreases α
f increases and is described well by the relation α
f=17·10−6 K−1+8.3·10−5 nm K−1
t
−1. This relation was used to estimate the linear expansion coefficient α
s of the C60 surface in the (111) plane as α
s=60·10−6K−1, which is several times larger than the bulk value. The experimental results agree satisfactorily with the theoretical calculations
of the mean-square displacements of molecules located in a region near the surface.
Zh. éksp. Teor. Fiz. 114, 1868–1875 (November 1998) 相似文献
10.
W. Schwarz E. H. Brandt K. -P. Döring U. Essmann K. Fürderer M. Gladisch D. Herlach G. Majer H. -J. Mundinger H. Orth A. Seeger M. Schmolz 《Hyperfine Interactions》1986,31(1-4):247-253
The diffusivityD
μ of positive muons (μ+) in the mixed state of superconducting high-purity, high-perfection niobium single crystals is investigated by measurements
of the relaxation of the transverse muon spin polarization (μ+SR). The method makes use of the strong magnetic field gradients existing in the mixed state of Type-II superconductors and
monitorsD
μ through the variation of the magnetic field felt by the μ+ during their diffusion through the crystals. For μ+ near the centres of the flux lines inNb it givesD
μ(4.6 K)=(8±2)·10−11m2S−1. The positive temperature coefficient ofD
μ indicates that at liquid-helium temperatures the diffusivity of μ+ inNb is mainly due to phonon-assisted tunnelling processes. 相似文献
11.
P. Dubé A. A. Madej J. E. Bernard L. Marmet A. D. Shiner 《Applied physics. B, Lasers and optics》2009,95(1):43-54
In this paper, we describe in detail a narrow linewidth and frequency-stable laser source used to probe the 5s
2
S
1/2–4d
2
D
5/2 clock transition of the 88Sr+ optical frequency standard. The performance of the laser system is investigated with studies of its frequency drift rates
and with high resolution spectra of the 88Sr+ clock transition. The observed short-term drift rates are typically in the range of 10 to 23 mHz/s, and the current long-term
drift rate is 13.9(3) mHz/s. The laser stability, after subtraction of linear drifts, reaches 5×10−16 at an averaging time of 3000 s. This high level of stability is attributed for the most part to stabilization of the reference
cavity at the temperature where the coefficient of linear thermal expansion crosses zero. An upper bound for the laser linewidth
is given by the observation of a Fourier-transform limited resonance of 4.3 Hz (Δν/ν=1×10−14) on the 88Sr+ clock transition. The effective averaging time during the linewidth measurements was about 100 s. 相似文献
12.
L. Ciaffoni B. L. Cummings W. Denzer R. Peverall S. R. Procter G. A. D. Ritchie 《Applied physics. B, Lasers and optics》2008,92(4):627-633
High resolution diode laser spectroscopy has been applied to the detection of hydrogen sulphide at ppm levels utilizing different
transitions within the region of the ν
1+ν
2+ν
3 and 2ν
1+ν
2 combination bands around 1.58 μm. Suitable lines in this spectral region have been identified, and absolute absorption cross
sections have been determined through single-pass absorption spectroscopy and confirmed in the Doppler linewidth regime using
cavity enhanced absorption spectroscopy (CEAS). The desire for a sensitive system potentially applicable to H2S sensing at atmospheric pressure has led to an investigation on suitable transitions using wavelength modulation spectroscopy
(WMS). The set-up sensitivity has been calculated as 1.73×10−8 cm−1 s1/2, and probing the strongest line at 1576.29 nm a minimum detectable concentration of 700 ppb under atmospheric conditions
has been achieved. Furthermore, pressure broadening coefficients for a variety of buffer gasses have been measured and correlated
to the intermolecular potentials governing the collision process; the H2S–H2S dimer well depth is estimated to be 7.06±0.09 kJ mol−1. 相似文献
13.
H. Zacharias R. Schmiedl K. H. Welge 《Applied Physics A: Materials Science & Processing》1980,21(2):127-133
State and isotope selective two-step photoionization of NO with mass spectroscopic ion detection has been demonstrated and
investigated. Using saturation condition the photoionization cross section for a single rotational level of the intermediate
state, No(A
2Σ+, ν′=0), has been measured: σi=(7.0±0.9) X 10−19 cm2. The charge transfer15NO++14NO→15NO+14NO+ has been observed and investigated, yielding a cross section of the order of 13×10−16 cm2, consistent with recent measurements at about 1 eV. 相似文献
14.
The characteristics of high current amorphous silicon diodes 总被引:1,自引:0,他引:1
R. A. Gibson P. G. Le Comber W. E. Spear 《Applied Physics A: Materials Science & Processing》1980,21(4):307-311
Amorphous siliconp−n junctions with various doping profiles have been prepared by the glow discharge technique and the effect of the barrier profile
on electrical properties investigated. Current densities of up to 40 A cm−2 with rectification ratios of 104–105 were obtained withn
+−ν−p
+ structures. The diode quality factor has also been investigated, both in the dark and under illumination. 相似文献
15.
V. K. Voronkova Yu. V. Yablokov J. Legendziewicz M. Bozechowska 《Physics of the Solid State》1999,41(12):1976-1979
The new heteronuclear crystal CuPr2(CCl3COO)8·6H2O, constructed of chains containing copper and praseodymium atoms, has been synthesized and investigated by EPR at 9.3 GHz
at temperatures ranging from room temperature down to 10 K. At temperatures T∼300–130 K, EPR spectra are observed which are characteristic of isolated polyhedra of copper ions with g
z=2.330±0.005, g
x,y
=2.053±0.005, A
z=139×10−4 cm−1, and A
x,y
<26×10−4 cm−1. At temperatures T<130 K a complex spectrum is observed, associated with the appearance of weak exchange interactions between the copper ions
in the chain (J
Cu-CuΣS
i·S
i+1), comparable in magnitude with the hyperfine interactions J
Cu-Cu=0.015 cm−1 at T=10 K. The magnitude of the exchange interaction decreases smoothly as the temperature is raised. It is conjectured that orbitals
of the praseodymium ions participate in the process of indirect exchange between the copper ions.
Fiz. Tverd. Tela (St. Petersburg) 41, 2154–2157 (December 1999) 相似文献
16.
We analyze the proton and deutron data on the spin-dependent asymmetry A
1(x, Q
2), supposing that the DIS structure functions g
1(x, Q
2) and F
3(x, Q
2) have a similar Q
2 dependence. As a result, we have found that Λ
1
p
−Λ
1
n
=0.190±0.038 at Q
2=10 GeV2 and Λ
1
p
−Λ
1
n
=0.165±0.026 at Q
2=3 GeV2; these values are in the best agreement with the Bjorken sum rule predictions.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 1, 9–14 (10 January 1997)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
17.
The static conductivity σ(E) and photoconductivity (PC) at radiation frequencies ħω=10 and 15 meV in Si doped with shallow impurities (density N=1016−6×1016 cm−3, ionization energy ε1≃45 meV) with compensation K=10−4−10−5 in electric fields E=10–250 V/cm are measured at liquid-helium temperatures T. Special measures are taken to prevent the high-frequency part of the background radiation (ħω>16 meV) from striking the
sample. It is found that the conductivity σ(E) is due to carrier motion along the D
− band, which is filled with carriers under the influence of the field E. In fields E<E
q
(E
q
≃100–200 V/cm) the carrier motion consists of hops along localized D
− states in a 10–15 meV energy band below the bottom of the free band (energy ε=ε1); for E>E
q
carriers drift along localized D
− states with energy ε∞ε1−10 meV. An explanation is proposed for the threshold behavior of the field dependence of the photo-and static conductivities.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 232–236 (25 August 1997) 相似文献
18.
The dielectric properties of polycrystalline (1−x)[0.7PbZrO3·0.3K0.5Bi0.5TiO3]·xSrTiO3 solid solutions, where x=0–0.7, are studied in the temperature range 150–600 K. Systematic spreading of the ferroelectric phase transition with increasing
strontium titanate content is discovered. The dispersion of the dielectric constant at frequencies from 10−1 to 106 Hz is investigated for a composition with x⋍0.7. The existence of two relaxation processes characterized by diffuse relaxation time spectra, which broaden with decreasing
temperature, is established. It is postulated that a transition to a glasslike state takes place in the material with x⋍0.7.
Zh. Tekh. Fiz. 69, 35–38 (March 1999) 相似文献
19.
Investigation of the effect of uniaxial pressure on antiferromagnetic resonance in KFe11O17 Crystals
The deformation dependence of the resonance field in KFe11O17 single crystals was investigated by the AFMR method. The measurements were performed at T=77 K and ν=47.52 GHz for two orientations of the external pressure. The experimental data are discussed in terms of a model of a very
simple easy-plane antiferromagnet taking account of the elastic and magnetoelastic contributions to the thermodynamic potential.
The magnetostriction, magnetoelastic, and elastic contants are calculated and the results are λ=1.94×10−5, B
1=2.75×108 erg/cm3, and C
11−C
12=1.42×1013 erg/cm3, respectively. The alues of these constants imply that the origin of the initial gap in the AFMR spectrum is not of magnetoelastic
origin.
Fiz. Tverd. Tela (St. Petersburg) 40, 513–515 (March 1998) 相似文献
20.
V. V. Skobelev 《Journal of Experimental and Theoretical Physics》1997,85(1):13-16
We consider axion formation processes in the synchrotron (e
−→e
−
a) and annihilation (e
−
e
+→a) channels in a constant crossed field F
μν
Fμν=Fμν*F
μν
=0, which approximates constant fields of other configurations in the ultrarelativistic asymptotic limit. The probability
and intensity of axion emission are obtained, and we analyze the energy and field asymptotics. A comparison with the characteristic
neutrino channel
yields the constraints on the axion mass and the energy scale for Peccei-Quinn symmetry breaking. Possible astrophysical
applications are discussed.
Zh. éksp. Teor. Fiz. 112, 25–31 (July 1997) 相似文献