409 research outputs found
Concentrations of 226Ra, 232Th, and 40K in the soils of Bangalore region, India.
Several soil samples of Bangalore region were analyzed for the concentrations of Ra, Th, and K by gamma ray spectrometry. The concentration of Ra varied in the range 7.7-111.6 Bq kg with a mean value of 26.2 Bq kg, Th in the range 16.7-98.7 Bq kg with a mean of 53.1 Bq kg, and that of K in the range 151.8-1424.2 Bq kg with a mean of 635.1 Bq kg. The external gamma absorbed dose rates in air were also measured using a portable environmental radiation dosimeter, and the gamma dose rates were found to vary in the range 61.4-201.7 nGy h with a mean of 117.2 nGy h. These results along with the results of estimation of radium equivalent activity (Raeq), absorbed dose rate (D), annual effective dose rate, external hazard index (Hex), internal hazard index (Hin), and representative level index (Igamma) are presented in this paper. The results are also compared with the literature values reported for other regions of India as well as worldwide average values and discussed
CONCENTRATIONS of 226Ra, 232Th, and 40K in the SOILS of BANGALORE REGION, INDIA
Several soil samples of Bangalore region were analyzed for the concentrations of 226Ra, 232Th, and 40K by gamma ray spectrometry. The concentration of 226Ra varied in the range 7.7–111.6 Bq kg−1 with a mean value of 26.2 Bq kg−1, 232Th in the range 16.7–98.7 Bq kg−1 with a mean of 53.1 Bq kg−1, and that of 40K in the range 151.8–1424.2 Bq kg−1 with a mean of 635.1 Bq kg−1. The external gamma absorbed dose rates in air were also measured using a portable environmental radiation dosimeter, and the gamma dose rates were found to vary in the range 61.4–201.7 nGy h−1 with a mean of 117.2 nGy h−1. These results along with the results of estimation of radium equivalent activity (Raeq), absorbed dose rate (D), annual effective dose rate, external hazard index (Hex), internal hazard index (Hin), and representative level index (Iγ) are presented in this paper. The results are also compared with the literature values reported for other regions of India as well as worldwide average values and discussed
More on scattering of Chern-Simons vortices
I derive a general formalism for finding kinetic terms of the effective
Lagrangian for slowly moving Chern-Simons vortices. Deformations of fields
linear in velocities are taken into account. From the equations they must
satisfy I extract the kinetic term in the limit of coincident vortices. For
vortices passing one over the other there is locally the right-angle
scattering. The method is based on analysis of field equations instead of
action functional so it may be useful also for nonvariational equations in
nonrelativistic models of Condensed Matter Physics.Comment: discussion around Eq.(45) is generalised, one more condition for the
local right-angle scattering is adde
Seasonal Variability of the Observed Barrier Layer in the Arabian Sea
The formation mechanisms of the barrier layer ( BL) and its seasonal variability in the Arabian Sea ( AS) are studied using a comprehensive dataset of temperature and salinity profiles from Argo and other archives for the AS. Relatively thick BL of 20-60 m with large spatial extent is found in the central-southwestern AS ( CSWAS), the convergence zone of the monsoon wind, during the peak summer monsoon ( July-August) and in the southeastern AS ( SEAS) and northeastern AS ( NEAS) during the winter ( January-February). Although the BL in the SEAS has been reported before, the observed thick BL in the central-southwestern AS during the peak summer monsoon and in the northeastern AS during late winter are the new findings of this study. The seasonal variability of BL thickness ( BLT) is closely related to the processes that occur during summer and winter monsoons. During both seasons, the Ekman processes and the distribution of low-salinity waters in the surface layer show a dominant influence on the observed BLT distributions. In addition, Kelvin and Rossby waves also modulate the observed BL thickness in the AS. The relatively low salinity surface water overlying the Arabian Sea high-salinity water ( ASHSW) provides an ideal ground for strong haline stratification in the CSWAS ( during summer monsoon) and in NEAS ( during winter monsoon). During summer, northward advection of equatorial low-salinity water by the Somali Current and the offshore advection of low-salinity water from the upwelling region facilitate the salinity stratification that is necessary to develop the observed BL in the CSWAS. In the SEAS, during winter, the winter monsoon current ( WMC) carries less saline water over relatively high salinity ambient water to form the observed BL there. The winter West India Coastal Current ( WICC) transports the low-salinity water from the SEAS to the NEAS, where it lies over the subducted ASHSW leading to strong haline stratification. Ekman pumping together with the downwelling Kelvin wave in the NEAS deepen the thermocline to cause the observed thick BL in the NEAS
Thermodynamic gauge-theory cascade
It is proposed that the cooling of a thermalized SU() gauge theory can be
formulated in terms of a cascade involving three effective theories with
successively reduced (and spontaneously broken) gauge symmetries, SU()
U(1) Z. The approach is based on the assumption that away
from a phase transition the bulk of the quantum interaction inherent to the
system is implicitly encoded in the (incomplete) classical dynamics of a
collective part made of low-energy condensed degrees of freedom. The properties
of (some of the) statistically fluctuating fields are determined by these
condensate(s). This leads to a quasi-particle description at tree-level. It
appears that radiative corrections, which are sizable at large gauge coupling,
do not change the tree-level picture qualitatively. The thermodynamic
self-consistency of the quasi-particle approach implies nonperturbative
evolution equations for the associated masses. The temperature dependence of
these masses, in turn, determine the evolution of the gauge coupling(s). The
hot gauge system approaches the behavior of an ideal gas of massless gluons at
asymptotically large temperature. A negative equation of state is possible at a
stage where the system is about to settle into the phase of the (spontaneously
broken) Z symmetry.Comment: 25 pages, 6 figures, 1 reference added, minor corrections in text,
errors in Sec. 3.2 corrected, PRD versio
Recent Results From Nb₃Sn Single Cell Cavities Coated at Jefferson Lab
Because of superior superconducting properties (Tc ~ 18.3K, Hs h~ 425 mT and Δ ~ 3.1 meV) compared to niobium, Nb₃Sn promise better RF performance (Q₀ and Eacc) and/or higher operating temperature (2 K Vs 4.2 K) for SRF cavities. Nb₃Sn-coated SRF cavities are produced routinely by depositing a few micron-thick Nb₃Sn films on the interior surface of Nb cavities via tin vapor diffusion technique. Early results from Nb₃Sn cavities coated with this technique exhibited precipitous low field Q-slope, also known as Wuppertal slope. Several Nb₃Sn single cell cavities coated at JLab appeared to exhibit similar Q-slope. RF testing of cavities and materials study of witness samples were continuously used to modify the coating protocol. At best condition, we were able to produce Nb₃Sn cavity with Q₀ in excess of ≥ 5×10¹⁰ at 2 K and ≥ 2×1010 at 4 K up the accelerating gradient of ~15 MV/m, without any significant Q-slope. In this presentation, we will discuss recent results from several Nb₃Sn coated single-cell cavities linked with material studies of witness samples, coating process modifications and the possible causative factors to Wuppertal slope
Electronic properties of ordered and disordered linear clusters of atoms and molecules
The electronic properties of one-dimensional clusters of N atoms or molecules
have been studied. The model used is similar to the Kronig-Penney model with
the potential offered by each ion being approximated by an attractive delta
function. The energy eigenvalues, the eigenstates and the density of states are
calculated exactly for a linear cluster of N atoms or molecules. The dependence
of these quantities on the various parameters of the problem show interesting
behavior. Effects of random distribution of the positions of the atoms and
random distribution of the strengths of the potential have also been studied.
The results obtained in this paper can have direct applications for linear
chain of atoms produced on metal surfaces or artificially created chain of
atoms by using scanning tunneling microscope or in studying molecular
conduction of electrons across one-dimensional barriers.Comment: A shorter version of this paper to be published in Physica
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
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