Two measurements of the β spectrum of S35 have been made using a windowless Si(Li) detector. The data show a clear threshold anomaly at Q-17 keV which is consistent with the emission of a 16.9±0.4 keV neutrino w...
Two measurements of the β spectrum of S35 have been made using a windowless Si(Li) detector. The data show a clear threshold anomaly at Q-17 keV which is consistent with the emission of a 16.9±0.4 keV neutrino with a mixing probability of (0.73±0.09±0.06)%. All values of mixing probability <0.26% are rejected at the 99% confidence level.
A measurement of the β spectrum of tritium implanted into a hyperpure germanium detector is reported. A distortion is observed 17 keV below the end point which is in agreement with an earlier measurement involving a ...
A measurement of the β spectrum of tritium implanted into a hyperpure germanium detector is reported. A distortion is observed 17 keV below the end point which is in agreement with an earlier measurement involving a tritium-implanted Si(Li) detector. The excess of counts observed in the low-energy region of the tritium spectrum is best described by the emission of a 16.9±0.1 keV neutrino and a mixing probability between 0.6 and 1.6% when allowance is made for uncertainty in the effective screening potential appropriate for tritium bound within a crystal lattice.
A string-breaking model for φφ production in the process π−p→φφn is discussed. In this model, the ‘‘sequential-pair-creation’’ model, it is assumed that the φφ pair is produced by ss¯ pairs created se...
A string-breaking model for φφ production in the process π−p→φφn is discussed. In this model, the ‘‘sequential-pair-creation’’ model, it is assumed that the φφ pair is produced by ss¯ pairs created sequentially: uū→s1s¯1→s1(s¯2s2) s¯1→(s1s¯2)(s2s¯1)→φφ. The second ss¯ pair is produced from the breaking of the QCD ‘‘string’’ joining the first ss¯ pair. When compared with experiment, the model appears to have problems in describing the data of Lindenbaum et al., and it helps to invoke Breit-Wigner resonances. The cross section for φφ production obtained from the model indicates that the experimental data may reflect the effects of some sort of enhancement.
Quark-pair transmutation via two gluons is the lowest-order, color-singlet process. In this paper the helicity amplitudes for this process are evaluated and a partial-wave analysis performed. The amplitudes for these ...
Quark-pair transmutation via two gluons is the lowest-order, color-singlet process. In this paper the helicity amplitudes for this process are evaluated and a partial-wave analysis performed. The amplitudes for these annihilations are infrared divergent and this divergence is removed by giving the gluons a confinement mass. The results are generally dependent on this mass. Many of the features are similar to those of quark-pair annihilation into two gluons. Somewhat surprisingly, there is a large proportion of a 1+ partial wave. Threshold effects are understood in terms of threshold effects in pair annihilation into two gluons. However, there is a ‘‘competition’’ effect that depends on the ratio of masses of the initial- and final-quark pairs. For similar masses, singlet production dominates as expected, but for very dissimilar masses, singlet annihilation of the heavier pair competes with triplet production of the lighter pair. Some comments about the possible applications and extensions of this work are made. Obvious applications are to the Okubo-Zweig-Iizuka-rule-suppressed decays of quarkonia. Other applications include development of a quark-pair-creation model that differs from the usual P03 and S13 models.
Anodic oxidation of thin Al films on GaAs beyond the exhaustion point is shown to induce substrate GaAs migration into and through the Al oxide layer. Continued anodization results in a triple‐layer structure compose...
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Anodic oxidation of thin Al films on GaAs beyond the exhaustion point is shown to induce substrate GaAs migration into and through the Al oxide layer. Continued anodization results in a triple‐layer structure composed of a surfaceGaAs oxide layer superimposed on top of a mixed Al oxide layer on a substrate GaAs oxide layer. The thicknesses and composition of these Al/GaAs composite oxides are measured using Rutherford backscattering spectrometry and are related to the specific final anodic voltages. The results show that, upon completion of the anodization of the Al layer, the Ga and or As ions drift under the action of the anodic field through the Al oxide. Eventually a new oxide is formed at the GaAs/oxide interface and also at the electrolyte/oxide interface in the ratio of 64:36.
Absorption spectra of dense helium gas at cryogenic temperatures has been acquired while the sample was irradiated using a 6.5 MeV protonbeam. By chopping the protonbeam, rather than the source lamp, we were able to a...
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Absorption spectra of dense helium gas at cryogenic temperatures has been acquired while the sample was irradiated using a 6.5 MeV protonbeam. By chopping the protonbeam, rather than the source lamp, we were able to achieve one part in 104 spectral sensitivity. The spectra showed six new bands in 4He2 and three in 3He2. These have been identified as transitions between high‐lying vibrational levels, with the strongest originating on the highest bound level of the a? 3Σ+ u potential. The temperature and pressure dependence of these features, as compared to low‐lying molecular and atomic features, offers some insight into the reactiondynamics of this fundamental system.
We have calculated some properties of the high-Tc superconductors by using the electron pairing induced by holes model proposed by us recently. The predicted dependence of Tc on the hole concentration δ agrees qualit...
We have calculated some properties of the high-Tc superconductors by using the electron pairing induced by holes model proposed by us recently. The predicted dependence of Tc on the hole concentration δ agrees qualitatively with the experimental data of Shafer et al. [Phys. Rev. B 36, 4047 (1987)]. The dependence of the normalized order parameter and the normalized gap energy on the reduced temperature are very close to the one given by the BCS theory of conventional superconductors. The ratio of the zero-temperature gap energy and Tc is near 1.6. The dependence of the density of states for quasiparticles on energy is found to be asymmetric. The carrier effective mass for 90-K superconductors is ∼4me.
Statistical equilibrium data from a time-ensemble data bank, generated for an anharmonic (15+2)-particle chain [Henry and Grindlay, Phys. Rev. A 38, 2594 (1988)], have been used to calculate coarse-grained distributio...
Statistical equilibrium data from a time-ensemble data bank, generated for an anharmonic (15+2)-particle chain [Henry and Grindlay, Phys. Rev. A 38, 2594 (1988)], have been used to calculate coarse-grained distributions for odd-mode velocities, particle velocities, and nearest-neighbor spring extensions. Each distribution proves to be Maxwellian in form. The mode-velocity temperatures agree with the mode-energy temperatures reported previously (Henry and Grindlay, ibid.). The time-ensemble data were also used to calculate averages and correlation functions for odd-mode energies, odd-mode velocities, particle velocities, spring energies, and their products. The dynamical response of the chain in the statistical equilibrium regime is found to be largely described by the behavior of modes 11, 13, and 15. These modes prove to be strongly correlated. The corresponding averages and correlation functions are calculated for a microcanonical ensemble of eight harmonic oscillators and compared with the time-ensemble results for the chain.
A scaling hypothesis is set up for the magnetization m(T,H;L), susceptibility χ(T,H;L), and correlation length ξ(T,H;L) of a finite-sized system, with O(n) symmetry (n≥2) and long-range interactions decaying as 1/...
A scaling hypothesis is set up for the magnetization m(T,H;L), susceptibility χ(T,H;L), and correlation length ξ(T,H;L) of a finite-sized system, with O(n) symmetry (n≥2) and long-range interactions decaying as 1/rd+σ (0<σ<2), confined to geometry Ld−d’×∞d’ (σ
Models of hadrons based on quantum chromodynamics predict new forms of hadronic matter, referred to as hybrids, with both quarks and excited glue degrees of freedom. I review theoretical models of hybrids with the aim...
Models of hadrons based on quantum chromodynamics predict new forms of hadronic matter, referred to as hybrids, with both quarks and excited glue degrees of freedom. I review theoretical models of hybrids with the aim of finding features of hybrids which transcend specific models. The goal is to find signatures that can distinguish between hybrids and conventional hadrons.
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