9,568 research outputs found
Theory of Complex Scattering Lengths
We derive a generalized Low equation for the T-matrix appropriate for complex
atom-molecule interaction. The properties of this new equation at very low
energies are studied and the complex scattering length and effective range are
derived.Comment: 9 page
Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations
In this Letter I argue that the Surrogate Method, used to extract the fast
neutron capture cross section on actinide target nuclei, which has important
practical application for the next generation of breeder reactors, and the
Trojan Horse Method employed to extract reactions of importance to nuclear
astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup
(INEB)Theory. Whereas the Surrogate Method relies on the premise that the
extracted neutron cross section in a (d,p) reaction is predominantly a compound
nucleus one, the Trojan Horse Method, assumes a predominantly direct process
for the secondary reaction induced by the surrogate fragment. In general, both
methods contain both direct and compound contributions, and I show how theses
seemingly distinct methods are in fact the same but at different energies and
different kinematic regions. The unifying theory is the rather well developed
INEB theory.Comment: 3 pages. Accepted for publication in the European Physical Journal A
(2017
Toward a microscopic description of reactions involving exotic nuclei
We propose an extension of the Continuum Discretized Coupled Channels (CDCC)
method, where the projectile is described by a microscopic cluster model. This
microscopic generalization (MCDCC) only relies on nucleon-target interactions,
and therefore presents an important predictive power. Core excitations can be
included without any further parameter. As an example we investigate the
\lipb elastic scattering at and 35 MeV. The Li nucleus is
known to present an cluster structure, and is well described by the
Resonating Group Method. An excellent agreement is obtained for the \lipb
elastic cross sections, provided that breakup channels are properly included.
We also present an application to inelastic scattering, and discuss future
applications of the MCDCC.Comment: 5 pages, 3 figures, Physical Review Letters (2013) in pres
Ultra cold neutrons: determination of the electric dipole moment and gravitational corrections via matter wave interferometry
We propose experiments using ultra cold neutrons which can be used to
determine the electric dipole moment of the neutron itself, a well as to test
corrections to gravity as they are foreseen by string theories and Kaluza-Klein
mechanisms.Comment: 3 pages, no figures, reference adde
Anxiety during pregnancy among Sudanese pregnant women
Many women suffer psychological symptoms during pregnancy but few studies have examined anxiety among pregnant ladies in relation to the level of education, previous bad obstetrical history and female circumcision. Aims: To determine frequency of anxiety among Sudanese women as related to pregnancy and customs related factors. Methods: 50 pregnant ladies and 50 matched controls were studied at the antenatal clinics of three major hospitals in Khartoum utilizing the Taylor Manifest Anxiety Scale. Data was fed to SPSS and significance was taken at P 0.05. Results: Three of the variables in the study were independently associated with anxiety during pregnancy. These were previous still birth (P 0.0370), female genital mutilation (pharaonic circumcision) (P 0.0070) and the low level of education (P 0.004). Keywords: pregnancy; anxietySudan Journal of Medical Science Vol. 1 (2) December 2006: 127-13
Condensed vortex ground states of rotating Bose-Einstein condensate in harmonic atomic trap
We study a system of Bose atoms trapped by a symmetric harmonic
potential, interacting via weak central forces. Considering the ground state of
the rotating system as a function of the two conserved quantities, the total
angular momentum and its collective component, we develop an algebraic approach
to derive exact wave functions and energies of these ground states. We describe
a broad class of the interactions for which these results are valid. This
universality class is defined by simple integral condition on the potential.
Most of the potentials of practical interest which have pronounced repulsive
component belong to this universality class.Comment: 34 pages, 10 ps figures, minor revisions, to be publ. in Ann. Phy
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