Resistivity measurements in silicon compressed by shock waves

Measurements of the relative resistance, $\text{R}\text{R}{}_0$, of p-type Silicon loaded by shock wave compression in the 〈 111 〉 direction, are reported. Stress amplitudes in the silicon were from 7 kb up to about 60kb.Electrical resistivity was found monotonically decreasing down to the ratio $\text{R}\text{R}{}_0$ ~ 0.14 at a stress amplitude of 34 kb. Then a sharp decrease to conducting state was detected at stresses over 56 kb.In the lower stress region the results are in agreement with theoretical calculations by Goroff and Kleinman [1]. The metallic transition observed in the neighbourhood of the Hugoniot Elastic Limit (55 kb) is suggested to be related to activation of plastic slip.     

Thermodynamical information on quark matter from the nucleon valence quark distribution

If the valence quarks in the nucleon are considered as a gas of the non-interacting massless particles, an expression of the xF₃(x) structure function is obtained which reproduces very well the experimental $\text{v(}\text{v}\text{)}$N data in the range 0.1?x?0.8. The effective temperature of such a quark gas is found to be of the order of 50 MeV.     

Ion implantation in amorphous germanium and silicon

The effects of Sb and Al implantation on the conductivity of amorphous Ge and Si film are reported. The room temperature conductivity of the vacuum deposited films is found to increase by a factor of 50 to 100 on implantation. The excess conductivity can be removed by annealing at 300°C for 6 hr. Results on a-Si films deposited in a partial pressure of H₂ also indicate that doping effect due to ion implantation is very small. The temperature dependence of conductivity of the films is found to obey a $\text{T}{}^{\mathrm{<mtext>?1</mtext><mtext>4</mtext>}}$ law before and after implantation. The value of T₀ is found to be rather insensitive to both hydrogenation and implantation.     

The impurity resistivity and resistivity minima in AlCr and AlMn alloys

The impurity resistivity of $\text{Al}$Cr between 1.5 and 50°K was determined with a characteristic temperature for the T² variation θ₁=960±40°K. The behaviour of the resistivity minimum both in $\text{Al}$Cr and $\text{Al}$Mn alloys with impurity concentration provides evidence that a T³ phonon resistivity is found also in aluminium with anomalous impurity resistivity.     

Constitution and magnetic properties of Ni-Mn-Sn alloys - solid and liquid state

Ternary Ni₅₀Mn_50-xSn_x alloys have been studied by means of the magnetothermal analysis. The high temperature phase of the Ni₂MnSn Heusler alloy is obtained directly from the melt (structure of B2 type). From the paramagnetic behaviour of the Heusler alloy in the liquid as well as solid states, the same magneton number $\text{n′}{}_{\mathrm{<mtext>eff</mtext>}}\text{? 5}$ per Mn atom results. At lower temperatures this phase forms the L2₁ structure and shows a resulting ferromagnetic magneton number $\text{n}{}_{\mathrm{rmf}}\text{? 4}$, a value which is well known.     

The 404.5-nm system of the ReO molecule

Observations on the emission spectrum of ReO in the region 375–870 nm are reported. Five bands of a $\text{ΔΩ}\text{= 0}$ system with (0, 0) band at 404.5 nm have been rotationally analyzed and the principal results for ¹⁸⁷ReO are (in cm^?1) ν₀ = 24 709.90, B′_e = 0.3819, B″_e = 0.4252, ω′_e = 874.8₂, and $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 979.1}{}_2$. Data on the minor isotopic species ¹⁸⁵ReO are also reported. It is suggested that broad rotational profiles found in bands near 842 nm may be due to nuclear hyperfine structure.     

The pressure dependence of the néel temperature in FeF2

A Mössbauer measurement of the pressure dependence of the Néel temperature in FeF₂ is reported. Up to the maximum pressure of 50 kbar T_N increases at the rate of 0.27 ± 0.03°K/kbar. When this pressure dependence is converted to volume dependence, the result, d In T_N/d In V = 3.2 ± 0.3, is found to obey the $\text{“10}\text{3}$ rule” established by Bloch for a wide variety of antiferromagnetic insulators.     

Resonance production in the reaction π±p→Ks0K±p at 30 and 50 GeV/c

The mass and momentum transfer spectra of the charged $\text{K}\text{K}$ system produced in the reaction π^±p→K_s⁰K^±p are analyzed. The data have been collected at the CERN SPS with the Geneva-Lausanne two-arm, non-magnetic spectrometer at 30 and 50 GeV/c incident momenta. The general features of the reactions at these energies and the results of partial-wave analyses of the two kaon system are presented.The channel is dominated by the diffractive production of even spin resonances. The spin 4 recurrence of the A₂(1320) is clearly observed at 2040 MeV (Γ=380 MeV. A new resonance is observed with a mass M=2450MeV and a width Γ=400 MeV; the quantum numbers of this state are found to be I^G(J^PC)=1^?(6++). The analysis also shows the decay of the decay of the meson ?′(1600) through the $\text{K}\text{K}$ channel at both energies.The production amplitudes are determined both as a function of the $\text{K}\text{K}$ effective mass and of the momentum transfer. Isoscalar natural parity exchange is dominant. The energy dependence between 10 and 50 GeV/c is shown to be well described by a Regge pole model based on the f-dominated pomeron hypothesis. We compare the production mechanisms of the 2⁺ resonances A₂(1320) and K¹(1430). Finally, we estimate the $\text{K}\text{K}$ branching ratios of the spin 4 A₂(2040) and spin 6 A₂(2450) resonances.     

Neutron-hole strength distributions in heavy nuclei: (II). The 144, 148, 152Sm(3He, α) 143, 147, 151Sm and the 144, 148, 150, 152, 154Sm(p,d) 143, 147, 149, 151, 153Sm reactions

Valence and deep-lying neutron-hole strengths corresponding to orbits near and well below the Fermi surface have been observed in high-resolution studies of the ^{144, 148, 152}Sm(³He, α) and of the ^{144, 148, 150, 152, 154}Sm(p, d) reactions at 70 and 42 MeV bombarding energy, respectively. The explored excitation energy range was 28 MeV for the (³He, α) experiment and about 12 MeV in the (p, d) study. Complete angular distributions have been measured in both cases and the data was analyzed within the framework of the distorted waves Born approximation theory of direct reactions.For the neutron closed shell target (¹⁴⁴Sm), in addition to the well-known fragmentation of the 2d_{$\text{5}\text{2}$} and 1g_{$\text{7}\text{2}$} valence-hole strength, a new bump observed around 7.6 MeV excitation energy is excited in both reactions. This structure corresponds to the 1g_{$\text{9}\text{2}$} inner-hole strength in ¹⁴³Sm and the analysis of the (³He, α) data suggests that more than 50% of the l = 4 strength can be found between 6 and 12 MeV. When one goes to the heavier Sm isotopes, the energy spacing between valence-hole states located above and just below the N = 82 shell decreases strongly and disappears in ¹⁵¹Sm as a result of increasing deformation.Combining good energy resolution and detailed analysis of the two reactions, rather complete spectroscopic information is obtained for the valence-hole strength distributions. With regard to inner-hole states, the energy spectra exhibit a narrow structure whose centroid energy decreases from 4.4 to 2.9 MeV when the mass number increases from A = 147 to A = 153. The main peak displays an asymmetric shape with an extremely large high-energy tail. The 1h_{$\text{11}\text{2}$} hole strength is split into the Nilsson Orbitals. The narrow bumps are found to carry a large fraction of the l = 5 and l = 2 hole strengths in ^{147,149,151,152}Sm isotopes. In the high-energy tail of the structures one observes overlapping and increasing spreading of the g_{$\text{7}\text{2}$}, 2d_{$\text{5}\text{2}$} and possibly 1g_{$\text{9}\text{2}$} inner-hole strengths due to the disappearance of the N = 82 shell gap between N = 83 and N = 89 neutron numbers. The experimental hole strengths distributions are compared where possible to the predictions of the quasiparticle-phonon nuclear model or to the simple Nilsson model.     

Gluinos and lower bounds for squark and slepton masses from jet plus missing-pT events at the pp collider

On the basis of a detailed phenomenological analysis, combined with the minimal N = 1 supergravity model, it is shown that the jet plus missing-p_T events at the p$\text{p}$ collider can only be explained by relatively light gluinos ($\text{m}\text{g}\text{?}\text{< m}\text{q}\text{?}$ with a mass of about 40 GeV. The resulting squark and slepton masses are then found to be $\text{q}\text{?}\text{> 50}$ GeV and $\text{m}\text{e}\text{?}\text{> 35}$ GeV.     

Resonance photoelectron spectroscopy from autoionization states of CH3I

Resonance photoelectron spectra of methyl iodide have been taken by exciting individual autoionizing Rydberg states, and measuring the ejected electron energies by a time of flight technique. A number of spectra were obtained from autoionization states which are members of two series, converging respectively to the ²E_{$\text{1}\text{2}$} (ν = 0) and ²E_{$\text{1}\text{2}$} (ν₂ =1) states of the ion. In addition to observing vibrational bands not previously reported, we found that the peak intensities are consistent with Bardsley's formulation of the configuration interaction theory of autoionization.     

NMR investigation of the structure of NiZrF6·.6H2O at low temperatures

Previous studies have shown that NiZrF₆.6H₂O can be described by an axial spin Hamiltonian with parameters g = 2.33 and $\text{D}\text{k}\text{= ?3.14}\text{K}$, and exhibits ferromagnetic ordering at T_c = 164mK. Our room temperature X-ray measurements confirm that NiZrF₆·.6H₂O is isomorphous with NiSnCl₆·.6H₂O and give lattice parameters of $\text{a = 6.55}\text{A}\text{?}$ and α = 96°09′. Proton NMR measurements show that there exist important molecular motions at room temperature and that the space group remains $\text{R}\text{3}$ down to liquid helium temperatures. The positions of all twelve protons have been determined and are found to lie on a sphere of radius 2.9 Å centered on the nickel ion.     

Elastic and inelastic scattering of 15 MeV polarized deuterons from isotopes of Ca,Cu, Sr,Zr, and Mo

The elastic and inelastic scattering of 15 MeV polarized deuterons from ⁴⁸Ca, ⁶³Cu, ⁸⁸Sr, ⁹⁰Zr, ⁹²Zr, and ⁹²Mo has been investigated. Angular distributions of the cross section and vector analyzing power iT₁₁ have been measured for all these nuclei; the tensor analyzing powers T₂₀ and T₂₂ have been studied for ⁹²Zr. Cross sections and vector analyzing powers are generally well explained by the optical model for elastic scattering and by the DWBA with a macroscopic form factor for the inelastic scattering; this is consistent with previous work. Distributions for ⁴⁸Ca, however, are poorly fitted. Anomalous behavior of the N = 50 nuclei found in the inelastic scattering of polarized protons is not present for deuterons. Tensor analyzing powers are not well explained by standard procedures: use of approximate folding model optical parameters did not improve the fits. The distribution of iT₁₁ for the $\text{1}\text{2}$^? state in ⁶³Cu is significantly different from the distributions for the $\text{5}\text{2}$^? and $\text{7}\text{2}$^? states.     

Vibrational assignments in the electronic spectra of thiazyl fluoride

The first assignments of ν₂, largely SF stretching mode, have been made for the $\text{A(}{}^1\text{A″)}$ and $\text{a(}{}^3\text{A″)}$ states of NSF. The fundamental frequencies are respectively 707 and 673 cm^?1. New hot band assignments are reported and the observed vibrational envelopes of hot band progressions display multiple maxima in agreement with the calculated Franck-Condon envelopes. A number of weak unassigned bands remain in the singlet spectrum which must be associated with either multiple quanta of ν₂′, another electronic state or both.     

Tunable diode laser measurements of the band strength and collision halfwidths of nitric oxide

The strength of the fundamental absorption band of nitric oxide at 5.3 μm and collision halfwidths of nitric oxide lines broadened by nitrogen, argon, and combustion gases were measured in absorption cell, flat flame and shock tube experiments using a tunable diode laser. Room temperature absorption measurements were made in an absorption cell filled with NO/N₂ or NO/Ar mixtures or with probe-extracted combustion gases. High temperature (to 2500 K) absorption measurements were performed for NO in N₂ and NO in Ar using a shock tube, and for NO in combustion gases using a flat flame burner.Absorption measurements were made on lines from 1860–1925 cm^?1, ($\text{Ω=}\text{1}\text{2}$ and $\text{3}\text{2}$,P($\text{5}\text{2}$-R ($\text{29}\text{2}$)) resulting in a band strength of 123±8 cm^-2 atm^?1 at 273.2 K. Collision halfwidth dependencies for each broadening species were examined as a function of rotational quantum number and temperature.     

The temperature dependence and anisotropy of the thermal conductivity in polyacetylene

Observations of anisotropic transport in (CH)_x reported to date have been made on stretch-oriented films in the plane of the film. We report the first observations of anisotropy in the thermal conductivity measured parallel and perpendicular to the plane of unstretched films. The room-temperature value measured along the film is $\text{50}\text{mW}\text{cm}\text{?}\text{K}$, and is almost a factor of 20 higher than that observed perpendicular to the film $\text{(}\text{3}\text{mW}\text{cm}\text{?}\text{K}\text{)}$. Finally, the temperature dependences for the parallel and perpendicular thermal conductivities are reported.     

Analysis of the high-temperature spin-glass susceptibility: Determination of the local magnetic exchange

New measurements are reported of the magnetic susceptibility above the freezing temperature T_f for noble-metal spin-glasses with $\text{1}\text{2}$ to 6 at.% Fe or Mn. The susceptibility for T_f<T?5 T_f is not Curie-Weiss, but local magnetic correlations manifest themselves and provide a key for the determination of the exchange interactions in spin-glasses. The exchange parameters J_n are resolved up to 5 neighbors for $\text{Au}$Fe, $\text{Cu}$Mn, $\text{Au}$Mn and $\text{Pt}$Mn through a configuration ensemble calculation which includes atomic short range order.     

On the miscibility gap of spinels MnxFe3−xO4+γ

Annealing experiments at 940±5°C on Mn_xFe_3?xO_4+γ system were carried out in order to determine the equilibrium miscibility limits. The samples were annealed for 200 hr in sealed quartz tubes and quenched. Coexisting phases and relevant parameters were determined by X-ray diffraction. The immiscibility interval at the annealing temperature has been found by converting the $\text{c}\text{a}$ ratios to corresponding x-values to be x_cub = 2.54±0.03, x_tetr = 2.73±0.03. The experiments concerning the possible influence of the oxygen content are also reported.A corrected version of the phase diagram based on the results obtained as well as on the critically selected data published previously by other authors had been suggested and discussed on the basis of a simple model.     

Some studies of T = 32 states in 17F

Measurements have been made of some parameters of the second and sixth $\text{T =}\text{3}\text{2}$ states in ¹⁷F. For the second state, the resonance energy was found to be E_p = 12.707 ± 0.001 MeV (E_n = 12.550±0.001 MeV), which agrees with and improves on the accuracy of earlier work. For the sixth $\text{T =}\text{3}\text{2}$ state, at E_p = 14.435 MeV, the γ-decay was determined to be predominantly γ₀ with a branch to the first excited state of Γ(γ₁)/Γ(γ₀) ≦ 0.14. Together with other work, this determines J^π to be $\text{3}\text{2}{}^{\mathrm{?}}$. The capture strength is found to be (2J + 1)Γ_pΓ_γ/Γ = 11.4 ± 2.6 eV.     

Magnetic moments of the 12+ isomeric states in 194, 196, 198Pb

The g-factor of the 12⁺ isomeric state in lead isotopes with A = 194, 196, 198 was measured using the time-differential perturbed angular distribution method (TDPAD). The values obtained are respectively g(194) = ?0.158(6); g(196) = ?0.157(7); g(198) = ?0.144(11). A more precise determination of the 12⁺ level half-life is also made. The g-factprs of these nuclear states, which are described with v(i_{$\text{13}\text{2}$})^?2 as the main configuration, are surprisingly constant over a large mass range (between A = 206 and 194). A core polarization analysis explains this trend: the polarization induced on neutrons in i_{$\text{13}\text{2}$} orbit decreases with the mass number A (blocking effect), but a compensation is provided by the other spin-orbit partners f_{$\text{7}\text{2}$}-f_{$\text{5}\text{2}$} and P_{$\text{3}\text{2}$}-P_{$\text{1}\text{2}$}.