4,679 research outputs found
Angular and energy dependence of cross sections for orbital 1 excitations
The main features of the cross sections of low-lying orbital
excitations with in heavy deformed nuclei are studied in RPA on
the example of Gd. The dependence of the DWBA E2 and M1 cross sections
on the scattering angle and incident
electron energy MeV is analyzed in PWBA. The cross section is
larger for M1 than for E2 transitions at any angle if MeV. The
longitudinal (Coulomb) C2 excitation dominates the E2 response for . Only transverse M1 and E2 excitations compete for
and the former one is dominant for fm.
The M1 response is almost purely orbital up to fm even in
backward scattering. Qualitative PWBA estimates based on the -dependence of
the form factors alone are not able to predict some important features of the
cross sections stemming from the strong magnetic and orbital
character of the studied 1 excitations. The expectation for M1 over E2
dominance in backward scattering should not be extended to higher momentum
transfers and incident energies.Comment: Latex, 28 pages, 12 postscript figures included using uufile
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The Bethe surface of liquid water.
The Bethe surface of liquid water, earlier calculated using a semi-empirical model, is compared with recent available data from IXS-experiments (inelastic X-ray scattering; Compton scattering of high energy photons) in liquid water. No alarming discrepancy is found on a global view of the Bethe surface. The extrapolation to the optical limit (viz., at zero momentum transfer) is shown and the reliability of these data is discussed in detail
Comprehensive track-structure based evaluation of DNA damage by light ions from radiotherapy- relevant energies down to stopping
Track structures and resulting DNA damage in human cells have been simulated for hydrogen, helium,
carbon, nitrogen, oxygen and neon ions with 0.25–256 MeV/u energy. The needed ion interaction cross sections have been scaled from those of hydrogen; Barkas scaling formula has been refined, extending its applicability down to about 10 keV/u, and validated against established stopping power data. Linear energy transfer (LET) has been scored from energy deposits in a cell nucleus; for very low-energy ions, it has been defined locally within thin slabs. The simulations show that protons and helium ions induce more DNA damage than heavier ions do at the same LET. With increasing LET, less DNA strand breaks are formed per unit dose, but due to their clustering the yields of double-strand breaks (DSB) increase, up to saturation around 300 keV/μm. Also individual DSB tend to cluster; DSB clusters peak around
500 keV/μm, while DSB multiplicities per cluster steadily increase with LET. Remarkably similar to patterns known from cell survival studies, LET-dependencies with pronounced maxima around 100– 200 keV/μm occur on nanometre scale for sites that contain one or more DSB, and on micrometre scale for megabasepair-sized DNA fragments
Averages of -hadron, -hadron, and -lepton properties as of summer 2014
This article reports world averages of measurements of -hadron,
-hadron, and -lepton properties obtained by the Heavy Flavor Averaging
Group (HFAG) using results available through summer 2014. For the averaging,
common input parameters used in the various analyses are adjusted (rescaled) to
common values, and known correlations are taken into account. The averages
include branching fractions, lifetimes, neutral meson mixing parameters,
violation parameters, parameters of semileptonic decays and CKM matrix
elements.Comment: 436 pages, many figures and tables. Online updates available at
http://www.slac.stanford.edu/xorg/hfag
Competing electric and magnetic excitations in backward electron scattering from heavy deformed nuclei
Important contributions to the cross sections of
low-lying orbital excitations are found in heavy deformed nuclei, arising
from the small energy separation between the two excitations with and 1, respectively. They are studied microscopically in QRPA using
DWBA. The accompanying response is negligible at small momentum transfer
but contributes substantially to the cross sections measured at for fm ( MeV)
and leads to a very good agreement with experiment. The electric response is of
longitudinal type for but becomes almost purely
transverse for larger backward angles. The transverse response
remains comparable with the response for fm
( MeV) and even dominant for MeV. This happens even at
large backward angles , where the dominance is
limited to the lower region.Comment: RevTeX, 19 pages, 8 figures included Accepted for publication in Phys
Rev
Averages of b-hadron Properties at the End of 2005
This article reports world averages for measurements on b-hadron properties
obtained by the Heavy Flavor Averaging Group (HFAG) using the available results
as of at the end of 2005. In the averaging, the input parameters used in the
various analyses are adjusted (rescaled) to common values, and all known
correlations are taken into account. The averages include lifetimes, neutral
meson mixing parameters, parameters of semileptonic decays, branching fractions
of B meson decays to final states with open charm, charmonium and no charm, and
measurements related to CP asymmetries
Construction of realistic hybrid computational fetal phantoms from radiological images in three gestational ages for radiation dosimetry applications
Radiation exposure and associated radiation risks are major concerns for fetal development for
pregnant patients who undergo radiation therapy or diagnostic imaging procedures. In order to
accurately estimate the radiation dose to the fetus and assess the uncertainty of fetal position and
rotation, three hybrid computational fetus phantoms were constructed using magnetic resonance
imaging (MRI) for each fetus model as a starting point to construct a complete anatomically accurate
fetus, gravid uterus, and placenta. A total of 27 fetal organs were outlined from radiological images
via the Velocity Treatment Planning System. The DICOM-Structure set was imported to Rhinoceros
software for further reconstruction of 3D fetus phantom model sets. All fetal organ masses were
compared with ICRP-89 reference data. Our fetal model series corresponds to 20, 31, and 35 weeks of
pregnancy, thus covering the second and third trimester. Fetal positions and locations were carefully
adapted to represent the real fetus locations inside the uterus for each trimester of pregnancy. The
new series of hybrid computational fetus models together with pregnant female models can be used
in evaluating fetal radiation doses in diagnostic imaging and radiotherapy procedures
Evidence for B- -> Ds+ K- l- nubar and search for B- -> Ds*+ K- l- nubar
We report measurements of the decays B- -> Ds(*)+ K- l- nubar in a data
sample containing 657x10^6 BBbar pairs collected with the Belle detector at the
KEKB asymmetric-energy e+e- collider. We observe a signal with a significance
of 6 sigma for the combined Ds and Ds* modes and find the first evidence of the
B- -> Ds+ K- l- nubar decay with a significance of 3.4 sigma. We measure the
following branching fractions: BF(B- -> Ds+ K- l nubar) = (0.30 +/- 0.09(stat)
+0.11 -0.08(syst)) x 10^-3 and BF(B- -> Ds*+ K- l- nubar) = (0.59 +/-
0.12(stat) +/- 0.15(syst)) x 10^-3 and set an upper limit BF(B- -> Ds*+ K- l-
nubar) < 0.56 x 10^-3 at the 90% confidence level. We also present the first
measurement of the Ds+K- invariant mass distribution in these decays, which is
dominated by a prominent peak around 2.6 GeV/c^2.Comment: Submitted to Phys. Rev.
Search for decays to invisible final states at Belle
We report a search for decays into invisible final states using a
data sample of pairs collected at the
resonance with the Belle detector at the KEKB
collider. The signal is identified by fully reconstructing a hadronic decay of
the accompanying meson and requiring no other particles in the event. No
significant signal is observed, and we obtain an upper limit of at the 90% confidence level for the branching fraction of invisible
decay.Comment: 6 pages, 5 figures (9 figure files
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