Smectic A order parameter measurements and critical scattering near the smectic A↔nematic phase transition in CBOOA

The temperature dependence of the order parameter for the smectic A phase of CBOOA is determined by measuring, with elastic coherent neutron scattering, the intensity of the Bragg reflection from the smectic layers. Within the experimental accuracy, the transition smectic A? nematic appears continuous in this system. However, a fit with (T_c-T)^2β yields β = 0.18 ± 0.01. Critical scattering is also observed in both phases. It can be described with an anisotropic Ornstein-Zernike law. The correlation length perpendicular to the smectic layers behaves like (T-T_c)^?v, with an exponent v = 0.47 ± 0.06. In contrast, the lateral extension of the layers seems to increase uncritically.     

Spin correlations in Ni-Mn-Ga

Results of measuring small-angle neutron scattering and neutron depolarization in a Ni_49.1Mn_29.4Ga_21.5 single crystal in the temperature range 15<T<400 K and in the range of magnetic fields 0<H<4.5 kOe are presented. The characteristic temperatures of the alloy were found to be as follows: T _C=373.7 K and the martensite transition temperature T _m=301–310 K. The magnetic critical scattering at T _C and the scattering at T<T _C were adequately described by the relationship I _m=A(q ²+κ²)^?2 (q is the transferred wave vector and R _c=1/κ is the correlation radius), and the temperature dependences of the A and R _c scattering parameters were determined. Left-right asymmetry was observed at 150<T< T _m in the scattering of neutrons polarized along or opposite to the applied field. This asymmetry was due to the inelastic magnetic interaction of neutrons in the sample. The magnetization of the alloy at T _m, critical scattering at T?T _C, anomalies in scattering, and the softening of magnetic excitations at 150 <T<T _m are discussed.     

Dynamics of the infinite-range ising spin glass

The Glauber dynamics of an Ising spin glass with infinite-range interactions and additional static field, h, is investigated near the freezing temperature, T_f. We obtain critical slowing down at and below the de Almeida-Thouless instability line, h_c(T), to order (1?T/T_f)³ with algebraic decay of the spin correlations ～t^?ν, where $\text{ν=}\text{1}\text{2}$ at T_f and $\text{ν≤}\text{1}\text{2}$ for T<T_f.     

Magnetic interaction and the critical dynamics above the curie point

It is shown that near T_c, where 4πχ ? 1 magnetic interaction completely change the long-wave critical dynamics of the ferromagnets and the new dynamic critical exponent is z_d = (5 - η)/2 - ν^-1 ≈ 1.     

Study of the heavy-fermion compound CeRu<Subscript>2</Subscript>Si<Subscript>2</Subscript> by the small-angle neutron scattering method

In order to directly observe neutron scattering by heavy fermion quasiparticles at low temperatures, a CeRu₂Si₂ single crystal has been studied by the small-angle neutron scattering method. In the experiment, neutron scattering is observed at T = 0.85 K for momentum transfers q ≤ 0.04 Å^?1, which is treated as the orbital component of magnetic scattering by heavy fermion quasiparticles. It has been found that the application of a magnetic field H = 1 T leads to both an increase in the observed scattering and its anisotropy with respect to the field direction. Moreover, measurements in the magnetic field reveal additional scattering for q > 0.04 Å^?1, which is well described by a Lorentzian and is interpreted as neutron magnetic scattering by spin-density fluctuations with a correlation radius R_c ≈ 30 Å.     

Experimental determination of the critical exponent η for nickel

The first unambiguous experimental determination of the critical exponent η, describing the critical point line shape of the spin correlation function, is presented for a three dimensional magnetic system. As a consequence of a finite value of η the critical scattering displays a maximum at T_max(q) above the Curie temperature T_c. The shift of the maximum with increasing scattering vector q was observed by a neutron small-angle experiment, yielding η=0.041±0.009 for a nickel single-crystal.     

Observation of possible production and decay of short-living heavy neutral particles in the SKAT neutrino experiment

In the SKAT bubble chamber neutrino experiment production of a short-living neutral particle with mass (1.4?m?2.5) GeV/c² and lifetime τ≈6×10^?12 s has been detected. The event may be interpreted as production and decay of the heavy lepton M⁰→μ^?+e⁺+ν_e with mass (1.4?m_M⁰?2.1) GeV/c². It might also be the production of a charmed particle D⁰→e⁺+τ^?+ν_e (D⁰→e⁺+π^?+ν_e) with mass 1.4?m_D⁰?2.5) GeV/c² in a non-diagonal neutral current. The probability to interpret the event as other possible processes is very low.     

Identification and intensities of the “forbidden” 3ν23 band of 12C16O2

Lines of the 3ν₂³ “forbidden” band of ¹²C¹⁶O₂ have been identified in the 2000-cm^?1 region of a long-path, 0.01-cm^?1 resolution laboratory absorption spectrum. This band has detectable intensity due to Δl = 2 Fermi interactions between the upper level and the nearby ν₁ + ν₂ and 3ν₂¹ levels. Intensities of 18 lines of this band have been measured using a nonlinear least-squares spectral fitting technique. The intensities are enhanced at high J and an expression for the intensity distribution as derived by Toth [Appl. Opt.23, 1825–1834 (1984)] is used for the analysis. In terms of the total sample pressure, the vibrational band intensity is 0.194 ± 0.008 × 10^?30 cm^?1/molecule-cm^?2 at 296 K. The coefficient in the F factor is analogous to the Coriolis coefficient ξ and has been determined to be ?0.0413 ± 0.0015. As expected by theory, its value is very close to that of ξ for the related ν₁ + ν₂ band.     

Measurement of np elastic scattering at high energies and very small momentum transfers

The np elastic differential cross section has been measured for incident neutron momenta 100–400 GeV/c in the |t| range 6 · 10^?6 ? 5 · 10^?1 (GeV/c)². The np data of this experiment provide a first direct measurement of the hadronic amplitude for |t| < 10^?2 (GeV/c)², which is consistent with the extrapolations from higher |t| values. Our data for |t| < 10^?4 (GeV/c)² are consistent with a rise which can be attributed to Schwinger scattering, caused by the interaction of the neutron magnetic moment with the proton.     

Nonlinear and nonlocal transport effects in simple fluids

Correlation function formulae for transport coefficients of 2nd order in arbitrarily dense fluids are derived, using a modified Chapman-Enskog solution of the Liouville equation. Some static correlations are neglected. Approximate evaluation for dilute gases gives essentially the same results as the solution of Boltzmann's equation. As an application higher order transport effects in the critical region are estimated. It is conjectured that they are apparent in sound absorption and the line width of Rayleigh scattering if (T?T_c)/T _c?10^?3.     

Anisotropy of critical X-ray scattering in the vicinity of smectic B-nematic phase transition in EPPCB

The high-resolution X-ray scattering has been used to study the anisotropy of the density correlation function in the vicinity of S_B-N phase transition in the recently developed material EPPCB. The effective critical exponents estimated in the temperature interval 10^?4 <t< 10^?2 (t = T/T_C ? 1) are: γ = 1.34 ± 0.09, ν_⊥ = 0.56 ± 0.08, ν_| = 0.70 ± 0.06 and fulfill, within experimental errors, the relation γ = ν_⊥ + ν_|.The novel feature is that the iso-intensity contours in the scattering plane containing the direction normal to the smectic layers have been found to be of four-winged shaped. A phenomenological (mean-field) theoretical approach explaining this shape in terms of the independence of fluctuations in the longitudinal (perpendicular to the smectic layers) and transversal (in the smectic planes) directions has been proposed.     

Analysis of the ν9 and ν10 bands of cyclopropane

The infrared spectrum of gaseous cyclopropane has been measured in the regions 980–1080 and 1400–1500 cm^?1, containing the ν₁₀ and ν₉E′ fundamental bands, respectively, using a high-resolution Fourier transform instrument. Deconvolution was used to enhance the resolution in the crowded parts of the spectrum to ～0.0020–0.0025 cm^?1. Apart from the rotational l-resonance affecting mainly the low-K subbands, the ν₉ band is strongly perturbed by Fermi resonance with the 2ν₁₄² state lying ～41 cm^?1 above. The effects of the Fermi resonance are most pronounced in the high-KΔK = +1 subbands as the 2ν₁₄^?2 levels would cross the ν₉⁺ levels near K = 30. ^rR lines of 2ν₁₄^?2 for K = 24 to 36, enhanced by the resonance, have been identified in the region 1469–1475 cm^?1 of the spectrum. Two extra perturbation-enhanced subbands are found adjacent to the K = 16?17 and K = 17?16 subbands of ν₉: these have been ascribed to the K = 18?17 transitions in 2ν₁₄^?2 and to the K = 19?16 transitions in $\text{ν}{}_2\text{2ν}{}_{14}{}^0$, respectively, as their upper states coincide with the corresponding levels ν₉^?(K = 16) and ν₉⁺(K = 17). A combination of l-resonance and Fermi resonance is mainly responsible for the interactions causing the perturbations and appearance of the extra subbands, but a direct rotational interaction 〈ν₉^?(K)|h₃|2ν₁₄^?2(K + 2)〉 also had to be introduced to accurately account for the observations. In contrast, the ν₁₀ band is not appreciably perturbed by other states and merely exhibits effects of strong l-resonance in the low-K subbands, and K-doubling of the high-J lines of the K = 2–3 subband. A detailed analysis of the spectrum and of the perturbations is described and sets of accurate spectroscopic constants are reported for ν₁₀ and ν₉ as well as for the perturbing state 2ν₁₄², which reproduce 3020 observed lines of the ν₁₀ band with a standard deviation of 0.0008 cm^?1 and 1810 lines of ν₉ with a standard deviation of 0.0010 cm^?1.     

Magnetic-field-induced slowing-down of molecular rotation in C<Subscript>60</Subscript> crystals

The molecular dynamics of C₆₀ crystals was studied by inelastic neutron scattering at T=290 K, i.e., above the first-order phase transition temperature (T_C≈260 K), in the region of free C₆₀-spheroid rotation in the lattice. The energy broadening of the original neutron spectrum 2Γ₀≈0.1 meV for a momentum transfer q=2 Å^?1 is in agreement with NMR data on the rotational relaxation time of the molecule τ～10^?11 s～ ?Γ₀. This effect was observed to decrease in magnetic fields H=2.5–4.5 kOe applied along the scattering vector: Γ_H=0.7Γ₀. The slowing-down of the molecular rotation is discussed in connection with the interaction of a magnetic field with the molecular currents, which fluctuate when the C₆₀ cage rotates.     

Critical correlation function to order ϵ3

The zero-field, two-point correlation function of an n-vector system in d = 4 ? ?dimensions is calculated to order ?³ for T ? T_c, using a dispersion theory approach to the scaling function g(g²ξ²)     

Fluctuations and defects in the spiral state of magnetic superconductors

We want to point out three properties of a magnetic superconductor: (i) The absence of true long-range order in the spiral state leads to the structure functions behaving like (q₆ ? q₀)^η?2 and (q²_⊥)^η?2 for q_⊥=0 and q₆=0, respectively, where q₀ is the preferred momentum. The indices η are measured via Bragg-like neutron scattering. (ii) The state is perforated by line-like defects. (iii) Above some critical temperature the defect lines proliferate, thereby destroying the spiral quasi-order.     

The moment of inertia of the proto neutron star PSR J0348+0432 under neutrino trapped

The moment of inertia of the proto neutron star PSR J0348+0432 is studied in the framework of relativistic mean field theory under neutrino trapped. We find that the temperature of the PNS PSR J0348+0432 increases with the increase of the baryon number density and at the center of the star it is in the range T_c = 41.662–45.685 MeV. Corresponding to the observation mass 1.97–2.05 M_⊙, the radius of the NS PSR J0348+0432 is in the range 12.948–12.16 km whereas that of the PNS PSR J0348+0432 is in the range 14.46–13.561 km. The radius of the PNS PSR J0348+0432 has increased by 11.7%–11.5% compared with that of the NS PSR J0348+0432. The central moment of inertia of the PNS PSR J0348+0432 is in the range 2.207?×?10⁴⁵–1.914?×?10⁴⁵ g cm² whereas that of the NS PSR J0348+0432 is only in the range 1.9?×?10⁴⁵–1.552?×?10⁴⁵ g cm². Compared with the moment of inertia of the NS PSR J0348+0432, the central moment of inertia of the PNS PSR J0348+0432 increases by 16%–23%.     

Diode laser measurements of strengths,half-widths,and temperature dependence of half-widths for CO2 spectral lines near 4.2 μm

Absolute line strengths have been measured at room temperature for spectral lines in the R branch of the ν₃ band of ¹²C¹⁶O₂, ¹²C¹⁶O¹⁸O, and ¹²C¹⁶O¹⁷O and the (ν₂ + ν₃) ? ν₂ and (ν₁ + ν₃) ? ν₁ bands of ¹²C¹⁶O₂ in the region 2365–2393 cm^?1 using a tunable diode laser spectrometer; from these measurements band strengths have been computed. Self- and nitrogen-broadened half-widths have been measured for some ν₃ lines of ¹²C¹⁶O₂ and ¹²C¹⁶O¹⁷O, and nitrogen-broadened half-widths measured for some (ν₂ + ν₃) ? ν₂ band lines of ¹²C¹⁶O₂. From measurements made over a temperature range from 217 to 299 K we have obtained temperature coefficients n, for the N₂-broadened Lorentz half-width defined as $\text{b}{}_{\mathrm{L}}{}^0\text{(T) = b}{}_{\mathrm{L}}{}^0\text{(T}{}_0\text{)(}\text{T}\text{T}{}_0\text{)}{}^{\mathrm{?n}}$, for the ν₃ and (ν₂ + ν₃) ? ν₂ bands of ¹²C¹⁶O₂. They are 0.757 ± 0.008 and 0.789 ± 0.015, respectively.     

Vibration-rotation spectra of CH3CN: The ν7 band and its hot bands near 1040 cm−1

Infrared spectra of CH₃CN were measured in the range 170–600 cm^?1 with a Fourier transform spectrometer (0.06 cm^?1 resolution) and several small portions in the range 1020–1065 cm^?1 with a tunable Pb_1?xSn_xTe diode laser spectrometer (0.001 cm^?1 resolution). The ν₇ band was analyzed by taking account of local Fermi resonance with 3ν₈¹, and the following parameters were determined: ν₇ = 1041.8446(15) cm^?1; 3ν₈¹ =1077.88(5) cm^?1; and ∥k₇₈₈₈∥ = 1.98(1) cm^?1. Two hot bands in the ν₇ band region, i.e., (ν₇ + ν₈)² ? ν₈¹ and ν₆¹ ? ν₈¹, were also analyzed, and ν₈ = 365.05(5) cm^?1 and ζ₈ = 0.874(1) were determined by use of the observed transitions of the ν₇ + ν₈ and ν₆ bands.     

Spinodal ordering in Cu3Au

Results from, X-ray diffuse scattering and inelastic neutron scattering demonstrate the presence of long-lived fluctuations in order up to 5.0°C above the first-order phase transition, T_c = 383.2°C. The temperature for continuous ordering has been determined to be 358.2°C. The coherent phase boundary is 3–13°C below T_c.     

<Emphasis Type="Italic">T</Emphasis>-odd correlation in polarized neutron decay

T-odd correlation [p_e, p_ν]η appears in the lowest order radiative correction to the polarized-neutron decay width, where δ is the polarization vector of a neutron. It appears as a consequence of the final-state interaction and should not be confused with real CP violation of the Standard Model. The asymmetry has the order of 10^?5. Final-state interaction in the decay of an unpolarized neutron causes the appearance of transverse polarization of a recoil proton and electron. Explicit expressions are given.