292 research outputs found
New representation of orbital motion with arbitrary angular momenta
A new formulation is presented for a variational calculation of -body
systems on a correlated Gaussian basis with arbitrary angular momenta. The
rotational motion of the system is described with a single spherical harmonic
of the total angular momentum , and thereby needs no explicit coupling of
partial waves between particles. A simple generating function for the
correlated Gaussian is exploited to derive the matrix elements. The formulation
is applied to various Coulomb three-body systems such as , and up to in order to show its usefulness and
versatility. A stochastic selection of the basis functions gives good results
for various angular momentum states.Comment: Revte
The frequency of the predominant Jewish mutations in BRCA1 and BRCA2 in unselected Ashkenazi colorectal cancer patients
It is presently unclear whether carriers of BRCA1 mutations have an increased risk for colorectal cancer (CRC). To gain insight into this issue, 225 unselected Ashkenazi Jewish CRC patients were tested for the presence of the three common Jewish BRCA1/2 germline mutations: 185delAG and 5382insC (BRCA1) and 6174delT (BRCA2). A total of four carriers was found (4/225, 1.78%). This frequency is similar to the estimated normal Ashkenazi population frequency, thus suggesting that these specific mutations do not contribute to CRC predisposition.© 2001 Cancer Research Campaign http://www.bjcancer.co
Competition of fusion and quasi-fission in the reactions leading to production of the superheavy elements
The mechanism of fusion hindrance, an effect observed in the reactions of
cold, warm and hot fusion leading to production of the superheavy elements, is
investigated. A systematics of transfermium production cross sections is used
to determine fusion probabilities. Mechanism of fusion hindrance is described
as a competition of fusion and quasi-fission. Available evaporation residue
cross sections in the superheavy region are reproduced satisfactorily. Analysis
of the measured capture cross sections is performed and a sudden disappearance
of the capture cross sections is observed at low fusion probabilities. A
dependence of the fusion hindrance on the asymmetry of the projectile-target
system is investigated using the available data. The most promising pathways
for further experiments are suggested.Comment: 8 pages, 7 figures, talk presented at 7th International
School-Seminar on Heavy-Ion Physics, May 27 - June 1, 2002, Dubna, Russi
Precise solution of few-body problems with stochastic variational method on correlated Gaussian basis
Precise variational solutions are given for problems involving diverse
fermionic and bosonic -body systems. The trial wave functions are chosen
to be combinations of correlated Gaussians, which are constructed from products
of the single-particle Gaussian wave packets through an integral
transformation, thereby facilitating fully analytical calculations of the
matrix elements. The nonlinear parameters of the trial function are chosen by a
stochastic technique. The method has proved very efficient, virtually exact,
and it seems feasible for any few-body bound-state problems emerging in nuclear
or atomic physics.Comment: 39 pages (revtex) + 3 figures (appended as compressed uuencoded .ps
files
GABRIELA : a new detector array for gamma-ray and conversion electron spectroscopy of transfermium elements
With the aid of the Geant4 Monte Carlo simulation package a new detection
system has been designed for the focal plane of the recoil separator VASSILISSA
situated at the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. GABRIELA
(Gamma Alpha Beta Recoil Investigations with the Electromagnetic Analyser
VASSILISSA) has been optimised to detect the arrival of reaction products and
their subsequent radioactive decays involving the emission of alpha- and
beta-particles, fission fragments, gamma- and X-rays, and conversion electrons.
The new detector system is described and the results of the first commissioning
experiments are presented.Comment: 24 pages, Submitted to NIM
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