487 research outputs found
Sub-Arcsecond Imaging of 3C123:108-GHz Continuum Observations of the Radio Hotspots
We present the results of sub-arcsecond 108 GHz continuum interferometric
observations toward the radio luminous galaxy 3C123. Using multi-array
observations, we utilize the high u,v dynamic range of the BIMA millimeter
array to sample fully spatial scales ranging from 0.5" to 50". This allows us
to make one-to-one comparisons of millimeter-wavelength emission in the radio
lobes and hotspots to VLA centimeter observations at 1.4, 4.9, 8.4, and 15 GHz.
At 108 GHz, the bright, eastern double hotspot in the southern lobe is
resolved. This is only the second time that a multiple hotspot region has been
resolved in the millimeter regime. We model the synchrotron spectra of the
hotspots and radio lobes using simple broken power-law models with high energy
cutoffs, and discuss the hotspot spectra and their implications for models of
multiple hotspot formation.Comment: 16 pages, 3 Figures, ApJ Accepte
Classification and realizations of type III factor representations of Cuntz-Krieger algebras associated with quasi-free states
We completely classify type III factor representations of Cuntz-Krieger
algebras associated with quasi-free states up to unitary equivalence.
Furthermore, we realize these representations on concrete Hilbert spaces
without using GNS construction. Free groups and their type
factor representations are used in these realizations.Comment: 11 page
Single extreme low dose/low dose rate irradiation causes alteration in lifespan and genome instability in primary human cells
To investigate the long-term biological effect of extreme low dose ionising radiation, we irradiated normal human fibroblasts (HFLIII) with carbon ions (290 MeV u−1, 70 keV μm−1) and γ-rays at 1 mGy (total dose) once at a low dose rate (1 mGy 6–8 h−1), and observed the cell growth kinetics up to 5 months by continuous culturing. The growth of carbon-irradiated cells started to slow down considerably sooner than that of non-irradiated cells before reaching senescence. In contrast, cells irradiated with γ-rays under similar conditions did not show significant deviation from the non-irradiated cells. A DNA double strand break (DSB) marker, γ-H2AX foci, and a DSB repair marker, phosphorylated DNA-PKcs foci, increased in number when non-irradiated cells reached several passages before senescence. A single low dose/low dose rate carbon ion exposure further raised the numbers of these markers. Furthermore, the numbers of foci for these two markers were significantly reduced after the cells became fully senescent. Our results indicate that high linear energy transfer (LET) radiation (carbon ions) causes different effects than low LET radiation (γ-rays) even at very low doses and that a single low dose of heavy ion irradiation can affect the stability of the genome many generations after irradiation
Gamma-Ray Spectroscopy of O and N Hypernuclei via the O reaction
he bound-state level structures of the O and
N hypernuclei were studied by -ray spectroscopy using
a germanium detector array (Hyperball) via the O ()
reaction. A level scheme for O was determined from the
observation of three -ray transitions from the doublet of states
(,) at MeV to the ground-state doublet (,). The
N hypernuclei were produced via proton emission from unbound
states in O . Three -rays were observed and the
lifetime of the state in N was measured by the
Doppler shift attenuation method. By comparing the experimental results with
shell-model calculations, the spin-dependence of the interaction is
discussed. In particular, the measured O ground-state doublet
spacing of 26.4 1.6 0.5 keV determines a small but nonzero strength
of the tensor interaction.Comment: 22 pages, 17 figure
Asymmetric Field Profile in Bose Glass Phase of Irradiated YBa2Cu3O7-d: Loss of Interlayer Coherence around 1/3 of Matching Field
Magneto-optical imaging in YBa2Cu3O7-d with tilted columnar defects (CD's)
shows an asymmetric critical-state field profile. The observed hysteretic shift
of the profile ridge (trough) from the center of the sample is explained by
in-plane magnetization originated from vortex alignment along CD's. The
extracted ratio of the in-plane to out-of-plane magnetization component has a
maximum at 1/5 of matching field () and disappears above ,
suggesting a reduction of interlayer coherence well bellow in the Bose
glass phase. Implications are discussed in comparison with the vortex liquid
recoupling observed in irradiated Bi2Sr2CaCu2O8+y.Comment: Revtex, 4 pages, 5 figures, also see a movie at
(http://www.ap6.t.u-tokyo.ac.jp/kitaka/Research/d-line/index_e.htm). This
manuscript will appear in Phys. Rev. Let
Study of the A(e,e') Reaction on H, H, C, Al, Cu and Au
Cross sections for the p()n process on H, H, C,
Al, Cu and Au targets were measured at the Thomas
Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the
nuclear transparencies. Data were taken for four-momentum transfers ranging
from =1.1 to 4.8 GeV for a fixed center of mass energy of =2.14
GeV. The ratio of and was extracted from the measured
cross sections for H, H, C and Cu targets at = 2.15
and 4.0 GeV allowing for additional studies of the reaction mechanism. The
experimental setup and the analysis of the data are described in detail
including systematic studies needed to obtain the results. The results for the
nuclear transparency and the differential cross sections as a function of the
pion momentum at the different values of are presented. Global features
of the data are discussed and the data are compared with the results of model
calculations for the p()n reaction from nuclear targets.Comment: 28 pages, 19 figures, submited to PR
Scaling of the F_2 structure function in nuclei and quark distributions at x>1
We present new data on electron scattering from a range of nuclei taken in
Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the
cross section for , which is sensitive to short range contributions to the
nuclear wave-function, and in deep inelastic scattering corresponds to probing
extremely high momentum quarks. This result agrees with higher energy muon
scattering measurements, but is in sharp contrast to neutrino scattering
measurements which suggested a dramatic enhancement in the distribution of the
`super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in
^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie
Scaling study of the pion electroproduction cross sections and the pion form factor
The H()n cross section was measured for a range of
four-momentum transfer up to =3.91 GeV at values of the invariant
mass, , above the resonance region. The -dependence of the longitudinal
component is consistent with the -scaling prediction for hard exclusive
processes. This suggests that perturbative QCD concepts are applicable at
rather low values of . Pion form factor results, while consistent with the
-scaling prediction, are inconsistent in magnitude with perturbative QCD
calculations. The extraction of Generalized Parton Distributions from hard
exclusive processes assumes the dominance of the longitudinal term. However,
transverse contributions to the cross section are still significant at
=3.91 GeV.Comment: 6 pages, 3 figure
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