6,238 research outputs found
Shell effect in Pb isotopes near the proton drip line
A mass formula (BWM) without shell effect is employed to study the variation
of the shell effect in Pb isotopes through comparison with the experimental
data. Unlike other macroscopic formulae, the BWM reproduces the general trend
of the binding energy versus neutron number curves of all the nuclei from Li to
Bi. The shell effect in Pb-isotopes reduces to ~56 keV at N=106 but, increases
gradually for N<106, indicating increasing shell effect in Pb near the proton
drip line.Comment: Presented at the Cluster03 Conference, 4 pages, 3 figures, uses
espcrc1.st
Reply to Comment on Extension of the Bethe-Weizsacker mass formula to light nuclei and some new shell closures
Some properties of the modified Bethe-Weizsacker mass formula (BWM) are
discussed. As BWM has no shell effect included, the extra-stability or,
magicity in nuclei clearly stands out when experimental mass data are compared
with BWM predictions. If the shell effect quenches, the BWM predictions come
closer to the experimental data.Comment: 2 pages, no figur
Self-trapping of a binary Bose-Einstein condensate induced by interspecies interaction
The problem of self-trapping of a Bose-Einstein condensate (BEC) and a binary
BEC in an optical lattice (OL) and double well (DW) is studied using the
mean-field Gross-Pitaevskii equation. For both DW and OL, permanent
self-trapping occurs in a window of the repulsive nonlinearity of the GP
equation: . In case of OL, the critical nonlinearities
and correspond to a window of chemical potentials
defining the band gap(s) of the periodic OL. The
permanent self-trapped BEC in an OL usually represents a breathing oscillation
of a stable stationary gap soliton. The permanent self-trapped BEC in a DW, on
the other hand, is a dynamically stabilized state without any stationary
counterpart. For a binary BEC with intraspecies nonlinearities outside this
window of nonlinearity, a permanent self trapping can be induced by tuning the
interspecies interaction such that the effective nonlinearities of the
components fall in the above window
Long-range interactions of hydrogen atoms in excited states. III. nS-1S interactions for n >= 3
The long-range interaction of excited neutral atoms has a number of
interesting and surprising properties, such as the prevalence of long-range,
oscillatory tails, and the emergence of numerically large can der Waals C_6
coefficients. Furthermore, the energetically quasi-degenerate nP states require
special attention and lead to mathematical subtleties. Here, we analyze the
interaction of excited hydrogen atoms in nS states (3 <= n <= 12) with
ground-state hydrogen atoms, and find that the C_6 coefficients roughly grow
with the fourth power of the principal quantum number, and can reach values in
excess of 240,000 (in atomic units) for states with n = 12. The nonretarded van
der Waals result is relevant to the distance range R << a_0/alpha, where a_0 is
the Bohr radius and alpha is the fine-structure constant. The Casimir-Polder
range encompasses the interatomic distance range a_0/alpha << R << hbar c/L,
where L is the Lamb shift energy. In this range, the contribution of
quasi-degenerate excited nP states remains nonretarded and competes with the
1/R^2 and 1/R^4 tails of the pole terms which are generated by lower-lying mP
states with 2 <= m <= n-1, due to virtual resonant emission. The dominant pole
terms are also analyzed in the Lamb shift range R >> hbar c/L. The familiar
1/R^7 asymptotics from the usual Casimir-Polder theory is found to be
completely irrelevant for the analysis of excited-state interactions. The
calculations are carried out to high precision using computer algebra in order
to handle a large number of terms in intermediate steps of the calculation, for
highly excited states.Comment: 17 pages; RevTe
Virtual Resonant Emission and Oscillatory Long-Range Tails in van der Waals Interactions of Excited States: QED Treatment and Applications
We report on a quantum electrodynamic (QED) investigation of the interaction
between a ground state atom with another atom in an excited state. General
expressions, applicable to any atom, are indicated for the long-range tails
which are due to virtual resonant emission and absorption into and from vacuum
modes whose frequency equals the transition frequency to available lower-lying
atomic states. For identical atoms, one of which is in an excited state, we
also discuss the mixing term which depends on the symmetry of the two-atom wave
function (these evolve into either the gerade or the ungerade state for close
approach), and we include all nonresonant states in our rigorous QED treatment.
In order to illustrate the findings, we analyze the fine-structure resolved van
der Waals interaction for nD-1S hydrogen interactions with n=8,10,12 and find
surprisingly large numerical coefficients.Comment: 6 pages; RevTe
Effect of Irrigation and Potash Levels on Keeping Quality of Potato
Irrigation and fertilizer are the most dominating factors, in deciding the keeping quality of potato. It is, therefore, essential to formulate the efficient, reliable and economically viable irrigation management strategy with the use of potassium nutrient in order to produce better keeping quality. The investigation comprising four levels of irrigation (25, 30, 35 and 40 mm CPE (Cumulative pan evaporation) and four levels of potash (0, 100, 125 and 150 kg/ha) was carried out at Research Farm of the Department of Vegetable Science, CCS Haryana Agricultural University, (Haryana) Hisar, India during two years to find out the optimum level of irrigation and potash for obtaining higher yield of potatoes with better keeping quality at ambient room temperature. The potato variety used for the investigation was Kufri Bahar. The treatments were laid out in a split plot design with three replications. The increasing levels of irrigation and potash showed significant improvement in keeping quality parameters of potato. Likewise, the values for physiological loss in weight and decay loss of potato tubers (%) at 15, 30, 45 and 60 days after harvest were the lowest with irrigation level 40 mm CPE and application of potash @ 150 kg/ha. The two years results suggest that the irrigation level 40 mm CPE along with potash @ 150 kg/ha has shown the best treatment combination for the storage of potato at ambient room temperature under semiarid conditions of Hisar (Haryana)
Subtraction of Newtonian Noise Using Optimized Sensor Arrays
Fluctuations in the local Newtonian gravitational field present a limit to
high precision measurements, including searches for gravitational waves using
laser interferometers. In this work, we present a model of this perturbing
gravitational field and evaluate schemes to mitigate the effect by estimating
and subtracting it from the interferometer data stream. Information about the
Newtonian noise is obtained from simulated seismic data. The method is tested
on causal as well as acausal implementations of noise subtraction. In both
cases it is demonstrated that broadband mitigation factors close to 10 can be
achieved removing Newtonian noise as a dominant noise contribution. The
resulting improvement in the detector sensitivity will substantially enhance
the detection rate of gravitational radiation from cosmological sources.Comment: 29 pages, 11 figure
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