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1.
The Larmor-precession frequencies for197Hg in Fe have been determined to beω L = 1291 ±25 MHz at 293 K andω L = 1334±25 MHz at 105 K. For199Hg in Feω L =1372±50 MHz has been measured at 293 K. The half-lives of the 5/2? states in197Hg and199Hg have been remeasured asT 1/2(197Hg)=8.1±0.16 nsec andT 1/2(199Hg)=2.45±0.05 ns, respectively. The magnetic moment of the 5/2? 158keV state in199Hg was redetermined by the integral perturbed angular correlation method in an external magnetic field of 47kG asμ(5/2 ? ) = 0.905±0.091 nm. With this new value consistency for the magnetic hyperfine fields at Hg in Fe measured with the TDPAC-method and with the NMR/ON-method is obtained. This fact is used to determine theg-factors of the 5/2? states in197Hg and199Hg more precisely fromω L -values given above:g(197Hg)=0.342(6);g(199Hg)=0.352(13). The magnetic moments of the first excited 2+ states in198–204Hg isotopes which rely on calibrations with the199Hg-g-factor, are revised.  相似文献   

2.
The low field (Ha.c. ⋍ 0.05 Oe) and low frequency (15 Hz) a.c. susceptibility has been measured for the amorphous alloys RE40Y23Cu37, with RE = Gd, Tb, Dy, Ho, andEr. The susceptibility exhibits a cusp, characteristic of a spin-glass phase transition from paramagnetic state. Gd40Y23Cu37 seems to exhibit a mixed ferromagnetic-spin glass phase below 62.5 K. Using the Sherrington-Kirkpatrick mean field theory, we have determined, from the observed cusps, the temperature dependence of the Edwards-Anderson spin glass order parameter, the dependence, consistent with theory, being in the form q(T) = A(TSGT)β, with β ⋍ 1.  相似文献   

3.
We measured the longitudinal and transverse polarization of prompt muons produced at ~2 GeV/c transverse momentum by the interaction of 28.5 GeV protons on tungsten. Both components of the polarization were found to be consistent with zero: PL = ?0.15 ± 0.18 and PT = 0.05 ± 0.05.  相似文献   

4.
Long-wavelength acoustic phonons have been studied for each of the [ζ00]T, [ζ00]L, [ζζ0]L and [ζζ0]T1 branches in solid Kr at T = 77 K by means of inelastic neutron scattering utilizing ‘cold neutrons’ as they are available in the long-wave length tail of the pile spectrum. The raw data have been corrected for resolution effects taking into account the curvature of the dispersion surface and variation of mode eigenvectors. It has turned out, that this yields appreciable shifts of the raw data. The results of our experiment give c11 = 4·25 ± 0·10, c44 = 2·04 ± 0·03, c12 = 2·82 ± 0·12 and a value for B = (c11 + 2c12)/3 = 3·30 ± 0·09 × 1010 dyne/cm2. Available thermodynamic data for Kr gives a derived value for Bad = 2·58 ± 0·06 × 1010 dyne/cm2 indicating a large difference between zero sound and first sound in solid Kr at high temperatures.  相似文献   

5.
In connection with the problem of identifying magnetic states in the vicinity of x 0 (the multicritical point of the x-T diagrams of spin-glass systems) a study has been made of properties that can be exploited to determine the presence of a thermodynamic phase transition at the Curie point T C and the distinctive features of the transition, specifically, the temperature dependence of the magnetic part of the specific heat C m(T), the temperature dependence of the low-field magnetization σ H(T), and (with a view toward examining critical behavior in a magnetic field) the magnetization isotherms σ H(T). The investigated object is the system of dilute ferrimagnetic spinels Li0.5Fe2.5−x GaxO4, in which every type of magnetic state has spatially inhomogeneous cluster structures. The results obtained for a sample with x=1.45 indicate that the classical criteria of a ferrimagnetic second-order phase transition at T C=(97±2) K occur for xx 0. The results of similar investigations for a sample with x=1.6, which exists in the cluster spin-glass state for T<T f=22 K and in an uncorrelated cluster state of the superparamagnetic type for T>T f, are also given for comparison with the preceding case. Zh. éksp. Teor. Fiz. 114, 2065–2077 (December 1998)  相似文献   

6.
A new magnetoelectric express method of determination of the Néel temperature, TN, has been developed. It permits to determine TN of the antiferromagnetic crystals, for which the magnetoelectric susceptability tensor is not equal to zero, with an accuracy ΔT = ±(2–3)°C for 30–40 min.  相似文献   

7.
As part of a study of large pT phenomena in photon-proton collisions at the CERN ISR, a search for direct single photon production has been performed. A statistical division of the data sample into the fraction consistent with single photon and the fraction due to multiphoton decays of neutral hadrons is accomplished by measuring the average conversion probability for the sample in a one radiation length thick converter. The fraction of the sample attributable to direct single photon production is 〈γ/all〉 = 0.074 ± 0.012 for 6 GeV/c < pT 10 GeV/c, and 〈γ/all〉 = 0.26 ± 0.04 for pT > 10 GeV/c, with an additional systematic uncertainty of ±0.05 for both values.  相似文献   

8.
Alignment tensor components 〈T(L) KQ + 〉 have been determined for the H(2p) charge exchange excitation in proton-argon collisions at an incident proton energy of 1.5 keV, and scattering angles Θ s =4.3°, 4.9°, and 6.0°. It is demonstrated that the measured photon angular distribution cannot be described in terms of only λ and ? parameters.  相似文献   

9.
The Coster-Kronig and Auger spectrum of theL 1 shell of gaseous argon has been investigated with an electrostatical spectrometer. The ionization in theL 1 shell of argon was caused by electron impact. Absolute energies and relative intensities of all the Coster-Kronig and Auger transitions have been determined. The relative intensities of transitions within the groupsL 1 L 2, 3 M 1,L 1 L 2, 3 M 2, 3 andL 1 MM agree fairly well with the theoretical values, calculated byRubenstein for extreme Russel-Saunders coupling, if intermediate coupling theory is used properly. Via the widthγ(L 1) of theL 1 level of argon, found in this experiment to be (1.84±0.2) eV, the following absolute group transition probabilities were determined (in units of 1014 sec?1):W(L1 L 2, 3 M 1)=(5.5±1.0),W(L1 L 2, 3 M 2, 3)=(20.8±2.8),W(L1 MM)=(1.44±0.16). The theoretical values are 21.0, 20.4 and 1.27. The possible reason for the large discrepancy between the experimental and theoretical value ofW(L1 L 2, 3 M 1) is the use of the incorrect value of 287 eV for the binding energyE(L1) byRubenstein. From the energies of theL 1 MM transitions this value has been determined to beE(L1)=(326.5±0.5) eV. This is the first direct measurement ofE(L1) of argon.  相似文献   

10.
Elastic electron scattering cross sections of27Al and Si (natural isotopic mixture) have been measured relative to carbon. The rms charge radiiR m , deduced with partial wave calculations, are (3.01±0.05) fm for27Al and (3.06±0.05) fm for Si, in good agreement with results from muonic X-ray energies. The values given are those for a Fermi charge distribution with skin thickness 2.5 fm; harmonic oscillator shell model distributions yield radii smaller by 0.03 fm. The ratioR m (27Al)/Rm(Si) is 0.984±0.016.  相似文献   

11.
We have studied by pulsed NMR a single crystal of 2HNbSe2 at ambient pressure and under hydrostatic pressure of 21 kbar in the temperature range 4.2–273 K. Our results are consistent with the onset of incommensurate charge density waves (ICDW) at TCDW = 33 K atP = 1 bar and 26 K at P = 21 kbar. Below TCDW, the lineshapes of the (m → m ? 1) transitions agree with a local distribution of Knight shift and electric field gradients respecting the symmetry of a triple ICDW, while above TCDW, pre-transitional broadening is observed. The product T1T = 500 ± 100 msk was found constant in the temperature range 4.2–77 K and pressure independant.  相似文献   

12.
We measured the elastic scattering of αα ats = 126 GeV and of αp at s = 89 GeV. For αα, the differential cross section dσ/dt has a diffractive pattern minima at |t| = 0.10 and 0.38 GeV2. At small |t| = 0.05?0.07 GeV2, this cross section behaves like exp[(100 ± 10) t]. Extrapolating a fit to the data to the optical point, we obtained for the total cross section αtot(αα) = 250 ± 50 mb and an integrated elastic cross section σe1(αα) = 45 ± mb. Another method of estimating σtot(αα), based on measuring the interaction rate, yielded 295 ± 40 mb. For αp, dσ/dt has aminimum at |t| = 0.20 GeV2, and for 0.05 < |t| < 0.18 GeV2 behaves like exp[(41 ± 2) t]. Extrapolating this slope to |t| = 0, we found σtot(αp) = 130 ± 20 and σe1(αp) = 20 ± 4mb. Results on pp elastic scattering at s = 63 GeV agree with previous ISR experiments.  相似文献   

13.
The [111] longitudinal sound velocity (v L) in a single-crystal synthetic opal has been measured at a frequency of 10 MHz in the temperature range 4.2–300 K. At 300 K, v L=2.1×105 cm/s. The quantity dv L/v 300 K(T) (where v T,K?v300 K) in the ranges 4.2–200 and 200–300 K behaves in the way typical of amorphous and crystalline solids, respectively.  相似文献   

14.
Squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione) is found to undergo a second order antiferrodistortive tetragonal to monoclinic phase transition at 97.7°C. The transition temperature for the fully deuterated compound is 243°C. The crystals are optically biaxial negative at room temperature, and the partial birefringence decreases with temperature as (nz ? ny)α(TC ? T)β, where βH = 0.34 ± 0.02 and βD = 0.37 ± 0.04.  相似文献   

15.
The boundary between the spin-glass state and the ferromagnetic state (pF-G) of the bond-random (±J) Ising model in the face-centred cubic lattice at T = 0 is calculated by the method of tetrahedron approximation in the simple version. The obtained value is, pF-G = 0.682, which is a little larger than the triple point pt = 0.654, and the model shows the reentrant behavior.  相似文献   

16.
The γ-ray spectrum of61Zn and60Zn was studied with a 75 cm3 Ge(Li) detector using mass separated sources. For the half-lives we foundT 1/2(61Zn)=89.1 ± 0.2 sec andT 1/2(60Zn)=2.33 ±0.05 min, together with the valuesT 1/2(61Cu)=3.26± 0.05 hr andT 1/2(60Cu)=24.0 ± 0.3 min for the half-lives of the daughter activities.  相似文献   

17.
Electrical resistivity, ?, has been measured as a function of temperature, T, of Cr alloys containing 0.47, 0.93, and 1.63 at.% Pt. The onset of antiferromagnetism causes anomalies in the ? vs T curves which increase with increasing Pt concentrations. Using the criterion that at the Néel temperature, TN, d?/dT is minimum, it has been determined that the values of TN are (430 ± 10)K, (490 ± 5)K, and (535 ± 5)K for the above-mentioned alloys. The nature of the antiferromagnetic state and the corresponding anomalies in the electrical resistivity in the Cr-Pt system are very similar to those found in Cr-Ir solid solutions.  相似文献   

18.
We have studied current-voltage characteristics of Andreev contacts in polycrystalline GdO0.88F0.12FeAs samples with bulk critical temperature T c = (52.5 ± 1) K using break-junction technique. The data obtained can- not be described within the single-gap approach and suggests the existence of a multi-gap superconductivity in this compound. The large and small superconducting gap values estimated at T = 4.2 K are Δ L = 10.5 ± 2 meV and Δ s = 2.3 ± 0.4 meV, respectively.  相似文献   

19.
The heat capacity of the layer compound, tetrachlorobis (methylammonium) manganese II, (CH3NH3)2MnCl4, has been measured over the range 10K <T<300K. In this region, two structural phase transitions have been observed previously by other techniques: one transition is from a monoclinic low temperature (MLT) phase to a tetragonal low temperature (TLT) phase, and the other is from TLT to an orthorhombic room temperature (ORT) phase. The present experiments have shown that the lower transition (MLT→TLT) occurs at T = 94.37±0.05K with ΔHt = 727±5 J mol?1 and ΔSt = 7.76±0.05 J K?1 mol?1, and the upper transition (TLT→ORT) takes place at T = 257.02±0.07K with ΔHt = 116±1J mol?1 and ΔSt = 0.451±0.004 J K?1mol?1. These results are discussed in the light of recent measurements on (CH3NH3)2CdCl4, and also with regard to a recent theoretical model of the structural phase transitions in compounds of this type.In addition to the structural phase transitions, (CH3NH3)2MnCl4 also undergoes magnetic ordering at T < 150K. The magnetic component to the heat capacity, as deduced from a corresponding states comparison of the heat capacity of the present compound with that of the Cd compound, is shown to be consistent with the behaviour expected for a quasi 2-dimensional Heisenberg antiferromagnet.  相似文献   

20.
The cation conductivity in the directions parallel (σ‖[001]) and perpendicular (σ⊥[001]) to the [001] crystallographic direction of Na4.6FeP2O8.6F0.4 single crystals has been investigated at 293–734 K. The specific features of the ionic conductivity have been studied near two phase transitions at T tr, 1 ~ 450 K and T tr, 2 ~ 545 K. At T = T tr, 1, the activation enthalpy for the dependences σ‖[001](T) and σ⊥[001](T) decreases from 0.45 ± 0.01 to 0.33 ± 0.02 eV, and the σ‖[001](T) curve has a jump of the ionic conductivity by a factor of almost two at T = T tr, 2; the jump is related to a manifestation of commensurate modulation of the crystal structure. In the Na4.6FeP2O8.6F0.4 crystals, the ionic transport is anisotropic with the ratio σ‖[001]⊥[001] = 7.7, 5.2, and 6.6 at 293 K (T < T tr, 1), 500 K (T tr, 1 < T < T tr, 2), and 700 K (T < T tr, 2), respectively. The mechanism of cation conductivity in the Na4.6FeP2O8.6F0.4 crystals is discussed.  相似文献   

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