56290496
TRACKING PARTICLES THROUGH A GENERAL MAGNETIC FIELD
A method that tracks particles directly through a general magneticfielddescribedina 3Dfield tablewasaddedto the code elegantrecently. It was realized by convertingan arbitrary particle’s motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.
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>>
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...
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
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.
13908197
Little string amplitudes (and the unreasonable effectiveness of 6D SYM)
A bstractWe study tree level scattering amplitudes of four massless states in the double scaled little string theory, and compare them to perturbative loop amplitudes in six-dimensional super-Yang-Mills theory. The little string amplitudes are computed from correlators in the cigar coset CFT and in N$$ \mathcal{N} $$ = 2 minimal models. The results are expressed in terms of integrals of conformal blocks and evaluated numerically in the α′ expansion. We find striking agreements with up to 2-loop scattering amplitudes of massless gluons in 6D SU(k) SYM at a ℤk invariant point on the Coulomb branch. We comment on the issue of UV divergence at higher loop orders in the gauge theory and discuss the implication of our results.
121363939
Guidelines for a supercollider experiment: the magnetic system
Abstract We try to give some general guidelines for optimizing the magnetic system of a general-purpose detector with a high momentum resolution for muons at a supercollider experiment. Solenoidal and toroidal schemes are investigated, with the possibility of using calorimeter material as the coil.
219179959
COMMISSIONING OF IMP 14.5GHZ ECR ION SOURCE
A 14.5 GHz.~ew. ECR ion source has been designed and constructed for the upgraded injection beam line of HIRF1.. SFC(Heavy Ion ~esearch FaCility m Lanzhou, Sector Focus Cyclotron) so that eventually two ECR ion sources could be available on the line. The new ECR Ion source has a compact struClUre with a high magnetic mirror ratio and a long chamber. The maximum axial magnetic field on the axis is around 1.5Tesla and the bexapole field on the chamber wall is I.OTesla. The ion source is being tested on the test bench. The preliminary results are typically 100 eJ1A of 0 7+, 160 eJ1A of Arll+ and 50 eJ1A of Xe26+. The design points, characteristics and commissioning are presented .
122172140
Band spectrum for an electron on a Sierpinski gasket in a magnetic field
Abstract We consider a quantum charged particle on a fractal lattice given by a Sierpinski gasket, submitted to a uniform magnetic field, in a tight binding approximation. Its band spectrum is numerically computed and exhibits a fractal structure. The groundstate energy is also compared to the superconductor transition curve measured for a Sierpinski lattice of superconducting material.
125646338
Alignment between the host and the nearest neighbor Groups
We measure four different types of alignment signals using the galaxy groups of the Sloan Digital Sky Survey Data Release 4 to probe the impact of large scale environment on the distribution of satellite galaxies, on the the orientation of the central and satellite galaxies: (1) the alignment between the distributions of the satellites relative to the direction of the nearest neighbor group (NNG); (2) the alignment between the major axis direction of the central galaxy of the host group (HG) and the direction of the NNG; (3) the alignment between the two major axes of the central galaxies of the HG and NNG; and (4) the alignment between the major axes of the satellites of the HG and the direction of the NNG. We find strong alignment signals of satellite distribution and orientation of central galaxy relative to the direction of the NNG even when the NNG locates beyond $3r_{\rm vir}$ of the host group. The alignment signals are stronger for groups that are more massive and with early type central galaxies. For the orientation of satellite galaxies, however, we do not find any significant alignment signals relative to the direction of the NNG. From these four types of the alignment measures, we conclude that the large scale environment traced by the nearby group mainly impacts the shape of the host dark matter halo, hence impacts the distribution of satellite galaxies and the orientation of central galaxies. Apart from these, there is additional impacts by the large scale environment directly onto the distribution of satellite galaxies.