37534317
New precise measurement of the pion weak form factors in pi+-->e+ nugamma decay.
We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-chi2 fits to the measured (E(e+), E(gamma) energy distributions result in the weak form factor value of F(A)=0.0119(1) with a fixed value of F(V)=0.0259. An unconstrained fit yields F(V)=0.0258(17) and F(A)=0.0117(17). In addition, we have measured a=0.10(6) for the dependence of F(V) on q2, the e+ nu pair invariant mass squared, parametrized as F(V)(q2)=F(V)(0)(1+aq(2)). The branching ratio for the kinematic region E(gamma)>10 MeV and theta(e(+)gamma)>40 degrees is measured to be B(expt)=73.86(54)x10(-8). Earlier deviations we reported in the high-E(gamma)-low-E(e+) kinematic region are resolved without a tensor term. We also derive new values for the pion polarizability alpha(E)=2.78(10)x10(-4) fm3 and neutral pion lifetime tau(pi0)=(8.5+/-1.1)x10(-17) s.
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.
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...
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>>
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.
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
120104096
High power CW linac in PNC
Power Reactor and Nuclear Fuel Development Corporation (PNC) is developing a high power electron linac for various applications. The electron beam is accelerated in CW operation to get maximum beam current of 100 mA and energy of 10 MeV. Crucial components such as a high power L-band klystron and a high power traveling wave resonant ring(TWRR) accelerator guides were designed and manufactured and their performance were examined. These design and results from the recent high power RF tests were described in this paper.<<ETX>>
118538481
Experimental Requirements to Determine the Neutrino Mass Hierarchy Using Reactor Neutrinos
This paper presents experimental requirements to determine the neutrino mass hierarchy using reactor neutrinos. The detector shall be located at a baseline around 58 km from the reactor(s) to measure the energy spectrum of electron antineutrinos ((nu)over bar(e)) precisely. By applying Fourier cosine and sine transforms to the L/E spectrum, features of the neutrino mass hierarchy can be extracted from the vertical bar Delta m(31)(2)vertical bar and vertical bar Delta m(32)(2)vertical bar oscillations. To determine the neutrino mass hierarchy above 90% probability, requirements to the baseline, the energy resolution, the energy scale uncertainty, the detector mass, and the event statistics are studied at different values of sin(2)(2 theta(13)).
120882513
Study of light hadron spectroscopy at BESIII
Using the samples of 2.25 × 108 J/ψ and 1.06 × 108 ψ′ events collected with the BESIII detector at the BEPCII e+e− collider in 2009, the pp mass threshold enhancement in J/ψ→γpp and X(1835) in J/ψ→γηπ+π− are confirmed. Two new resonances, X(2120) and X(2370), are also observed in the η′π+π− invariant mass spectrum. A narrow structure denoted as X(1870) is seen with a significance of 7.2σ in J/ψ→ωηπ+π−, and the branching ratio of J/ψ→ωη (1405), η(1405)→a0±(980)π∓, a0±(980)→ηπ± is measured for the first time. Direct measurements of a00(980)−f0(980) mixing in the processes J/ψ→φf0(980)→φa00(980)→φηπ0 and ψ′→γχc1, χc1→π0a00(980)→π0f0(980)→π0π+π− are presented to probe the properties of these two scalar states.Using the samples of 2.25 × 108 J/ψ and 1.06 × 108 ψ′ events collected with the BESIII detector at the BEPCII e+e− collider in 2009, the pp mass threshold enhancement in J/ψ→γpp and X(1835) in J/ψ→γηπ+π− are confirmed. Two new resonances, X(2120) and X(2370), are also observed in the η′π+π− invariant mass spectrum. A narrow structure denoted as X(1870) is seen with a significance of 7.2σ in J/ψ→ωηπ+π−, and the branching ratio of J/ψ→ωη (1405), η(1405)→a0±(980)π∓, a0±(980)→ηπ± is measured for the first time. Direct measurements of a00(980)−f0(980) mixing in the processes J/ψ→φf0(980)→φa00(980)→φηπ0 and ψ′→γχc1, χc1→π0a00(980)→π0f0(980)→π0π+π− are presented to probe the properties of these two scalar states.
208867768
Inclusive $J/\psi$ production in $pp$ collisions at $\sqrt{s} = 2.76$ TeV
The ALICE Collaboration has measured inclusive J/psi production in pp collisions at a center of mass energy sqrt(s)=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5
54921026
Measurement of the light antiquark flavor asymmetry in the nucleon sea
A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140000 Drell-Yan muon pairs with dimuon mass M{sub {mu}{sup +}{mu}{sup {minus}}}{ge}4.5 GeV/c{sup 2} were recorded. From these data, the ratio of antidown ({bar d} ) to antiup ({bar u} ) quark distributions in the proton sea is determined over a wide range in Bjorken x . A strong x dependence is observed in the ratio {bar d}/{bar u} , showing substantial enhancement of {bar d} with respect to {bar u} for x{lt}0.2 . This result is in fair agreement with recent parton distribution parametrizations of the sea. For x{gt}0.2 , the observed {bar d}/{bar u} ratio is much nearer unity than given by the parametrizations. {copyright} {ital 1998} {ital The American Physical Society}