119472658
Constraints on neutrino degeneracy from the cosmic microwave background and primordial nucleosynthesis
We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy based upon the latest high resolution CMB sky maps from BOOMERANG, DASI, and MAXIMA-1. We generate likelihood functions by marginalizing over $(\omegab h^2,\xinumt, \xinue, \Omega_\Lambda,h,n)$ plus the calibaration uncertainties. We consider flat $\Omega_M + \Omega_\Lambda = 1$ cosmological models with two identical degenerate neutrino species, $\xinumt \equiv \vert \xinum \vert = \vert \xinut \vert$ and a small $\xinue$. We assign weak top-hat priors on the electron-neutrino degeneracy parameter $\xinue$ and $\Omega_b h^2$ based upon allowed values consistent with the nucleosynthesis constraints as a function of $\xinumt$. The change in the background neutrino temperature with degeneracy is also explicitly included, and Gaussian priors for $h = 0.72 \pm 0.08$ and the experimental calibration uncertainties are adopted. The marginalized likelihood functions show a slight (0.5$\sigma$) preference for neutrino degeneracy. Optimum values with two equally degenerate $\mu$ and $\tau$ neutrinos imply $\xinumt = 1.0^{+0.8 (1\sigma)}_{-1.0 (0.5\sigma)}$, from which we deduce $\xi_{\nu_e} = 0.09^{+0.15}_{-0.09}$, and $\Omega_b h^2 = 0.021^{+0.06}_{- 0.002}$. The $2\sigma$ upper limit becomes $ \xinumt \le 2.1$, which implies $\xi_{\nu_e} \le 0.30$, and $\Omega_b h^2 \le 0.030$. For only a single large-degeneracy species the optimal value is $\vert \xinum \vert$ or $\vert \xinut \vert = 1.4$ with a $2\sigma$ upper limit of $\vert \xinum \vert$ or $\vert \xinut \vert \le 2.5$
22794424
Dipole and spin-dipole resonances in charge-exchange reactions on 12C.
The [sup 12]C([ital n],[ital p])[sup 12]B reaction was studied using the white neutron source at the Los Alamos Meson Physics Facility/Weapon Neutron Research Center with a continuous incident neutron energy from 60 to 260 MeV. Double differential cross sections were measured in the angular range 11[degree][le][theta][sub lab][le]37[degree]. Using the neutron time-of-flight facility at the Indiana University Cyclotron Facility, we also studied the [sup 12]C([ital p],[ital n])[sup 12]N reaction at [ital E][sub [ital p]]=186 MeV and the [sup 12]C([ital [rvec p]],[ital [rvec n]])[sup 12]N reaction at [ital E][sub [ital [rvec p]]]=160 and 186 MeV. Double differential cross sections were measured between [theta][sub lab]=0[degree] and [theta][sub lab]=50[degree] in 5[degree] steps. Spin observables [ital D][sub [ital N][ital N]], [ital A][sub [ital Y]], and [ital P] were measured at [theta][sub lab]=5[degree],9[degree],13[degree] with [ital E][sub [ital [rvec p]]]=160 MeV and [theta][sub lab]=15[degree],20[degree] with [ital E][sub [ital [rvec p]]]=186 MeV. Angular distributions of differential cross section and spin observables for low-lying transitions in the residual nuclei are compared with disorted-wave impulse approximation (DWIA) calculations. A multipole decomposition analysis was performed to study the giant dipole and giant spin-dipole resonances. The contributions of the quasifree reaction in the giant resonance region was subtracted. The empirical results ofmore » energy distributions for dipole ([Delta][ital L]=1) transition are compared with DWIA calculations using nuclear structure information obtained with a conventional shell model and also with a random phase approximation.« less
5742840
Crystallization in the Thin and Ultrathin Films of Poly(ethylene-vinyl acetate) and Linear Low-Density Polyethylene
The crystallization of poly(ethylene−vinyl acetate) and linear low-density polyethylene (LLDPE) films spun-cast from the polymer/toluene solutions with as-cast thickness from 460 to 10 nm was studied. The lamellar thickness was measured using small-angle X-ray scattering (SAXS) and found to increase from 14 to 21 nm for films thinner than 100 nm. The morphology of LLDPE measured by scanning probe microscopy (SPM) showed an edge-on lamellae for the films thicker than 30 nm and flat-on lamellae for the films thinner than 15 nm. A pseudo-“shish-kebab” tiny crystal structure was observed in between the larger lamellae. Crystallinity was confirmed using attenuated total reflectance−Fourier transformed infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The shear modulation force microscopy technique (SMFM) was used to measure the melting point, Tm, which was found to decrease for films thinner than 100 nm. The rate of decrease was a function of the annealing pr...
1289258
Energetic electrons associated with magnetic reconnection in the magnetic cloud boundary layer.
Here is reported in situ observation of energetic electrons (∼100-500 keV) associated with magnetic reconnection in the solar wind by the ACE and Wind spacecraft. The properties of this magnetic cloud driving reconnection and the associated energetic electron acceleration problem are discussed. Further analyses indicate that the electric field acceleration and Fermi-type mechanism are two fundamental elements in the electron acceleration processes and the trapping effect of the specific magnetic field configuration maintains the acceleration status that increases the totally gained energy.
10177650
Clarification of the three-body decay of 12C (12.71 MeV).
Using beta decays of a clean source of 12N produced at the IGISOL facility, we have measured the breakup of the 12C (12.71 MeV) state into three alpha particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed.
120316681
Experimental results of the betatron sum resonance
The experimental observations of motion near the betatron sum resonance, /spl nusub x/+2/spl nusub z/=13, are presented. A fast quadrupole (Panofsky-style ferrite picture-frame magnet with 8 pulsed power supplies) producing a betatron tune shift of the order of 0.03 at rise time of 1 /spl mu/s was used. This quadrupole was used to produce betatron tunes which jumped past and then crossed back through a betatron sum resonance line. The beam response as function of initial betatron amplitudes were recorded turn by turn. The correlated growth of the action variables, J/sub x/ and J/sub z/, was observed. The phase space plots in the resonance frame reveal the features of particle motion near the nonlinear sum resonance region.<<ETX>>
14787557
Solution Transformations for GS String in AdS_5 x S^5 by Conserved Quantities
For Light-cone gauge of Green-Schwarz superstring in AdS_5 x S^5 background, we fix two bosonic variables x^{+}=\tau and y^{9}=\sigma, and then perform the partial Legendre transformation of the remaining bosonic variables. We then obtain a Lagrangian which is linear in velocity after eliminating the metric of world sheet. For such a system, one can formulate its poisson bracket and Hamiltonian. Since this system is free and without constraint, the hierarchy of infinite nonlocal conserved quantities given by Bena, Polchinski and Roiban, induce solution transformations due to Jacobi identity.
118640758
Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys
We examine whether future, nearly all-sky galaxy redshift surveys, in combination with CMB priors, will be able to detect the signature of the cosmic neutrino background and determine the absolute neutrino mass scale. We also consider what constraints can be imposed on the effective number of neutrino species. In particular we consider two spectroscopic strategies in the near-IR, the so-called ``slitless'' and ``multi-slit'' approaches, whose examples are given by future space-based galaxy surveys, as EUCLID for the slitless case, or SPACE, JEDI, and possibly WFIRST in the future, for the multi-slit case. We find that, in combination with Planck, these galaxy probes will be able to detect at better than 3-sigma level and measure the mass of cosmic neutrinos: a) in a cosmology-independent way, if the sum of neutrino masses is above 0.1 eV; b) assuming spatial flatness and that dark energy is a cosmological constant, otherwise. We find that the sensitivity of such surveys is well suited to span the entire range of neutrino masses allowed by neutrino oscillation experiments, and to yield a clear detection of non-zero neutrino mass. The detection of the cosmic relic neutrino background with cosmological experiments will be a spectacular confirmation of our model for the early Universe and a window into one of the oldest relic components of our Universe.
17248811
A new surface treatment for the prototype RPCs of the BESIII spectrometer
The prototype resistive plate chambers (RPCs) for the BESIII spectrometer were constructed by using resistive electrodes made from a special type of phenolic paper laminates developed by us. The surface quality of these laminates is superior to other bakelite plates that have been used to construct RPCs elsewhere. A method for adjusting the resistivety of these laminates was also developed. Extensive studies were conducted by using a number of prototype RPCs in the last several years. Tests have shown prototype RPCs made by using our resistive plates without the linseed oil treatment can achieve the level of performance comparable to RPCs with linseed oil treated bakelite or resistive glass electrodes. In this paper, we will discuss the construction of these prototype RPCs. The test results of a prototype RPC that have been monitored for a year will be reported. Based on favorable test results of prototypes, the RPC production for the muon identifier of the BESIII spectrometer has started at the Beijing Gaonengkedi Science and Technology Co. Ltd. in early 2004 using the technology that we developed.
119387792
Model-independent Constraints on Dark Energy Density from Flux-averaging Analysis of Type Ia Supernova Data
We reconstruct the dark energy density X(z) as a free function from current Type Ia supernova (SN Ia) data, together with the cosmic microwave background (CMB) shift parameter from CMB data from the Wilkinson Microwave Anisotropy Probe (WMAP), Cosmic Background Imager (CBI), and Arcminute Cosmology Bolometer Array Receiver (ACBAR), and the large-scale structure (LSS) growth factor from the Two-Degree Field (2dF) galaxy survey data. We parameterize X(z) as a continuous function, given by interpolating its amplitudes at equally spaced z-values in the redshift range covered by SN Ia data, and a constant at larger z [where X(z) is only weakly constrained by CMB data]. We assume a flat universe and use the Markov Chain Monte Carlo (MCMC) technique in our analysis. We find that the dark energy density X(z) is constant for 0<~z<~0.5 and increases with redshift z for 0.5<~z<~1 at a 68.3% confidence level, but is consistent with a constant at a 95% confidence level. For comparison, we also give constraints on a constant equation of state for the dark energy. Flux averaging of SN Ia data is required to yield cosmological parameter constraints that are free of the bias induced by weak gravitational lensing. We set up a consistent framework for flux-averaging analysis of SN Ia data, based on the work of Wang. We find that flux averaging of SN Ia data leads to slightly lower m and smaller time variation in X(z). This suggests that a significant increase in the number of SNe Ia from deep SN surveys on a dedicated telescope is needed to place a robust constraint on the time dependence of the dark energy density.
119247594
Investigate the interaction between dark matter and dark energy
In this paper we investigate the interaction between dark matter and dark energy by considering two different interacting scenarios, i.e. the cases of constant interaction function and variable interaction function. By fitting the current observational data to constrain the interacting models, it is found that the interacting strength is non-vanishing, but weak for the case of constant interaction function, and the interaction is not obvious for the case of variable interaction function. In addition, for seeing the influence from interaction we also investigate the evolutions of interaction function, effective state parameter for dark energy and energy density of dark matter. At last some geometrical quantities in the interacting scenarios are discussed.