65 research outputs found
Isomeric states in No
6 pagesInternational audienceIsomeric states in 253No have been investigated by conversion-electron and gamma-ray spectroscopy with the GABRIELA detection system. The 31 micro second isomer reported more than 30 years ago is found to decay to the ground state of 253No by the emission of a 167 keV M2 transition. The spin and parity of this low-lying isomeric state are established to be 5/2+. The presence of another longer-lived isomeric state is also discussed
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
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic
CrĂ©ation de lacunes K lors d'une Ă©mission ÎČ de faible Ă©nergie : 203Hg â 203*Tl (279 keV)
The internal K ionization accompanying the ÎČ decay of mercury 203 feeding the 279 keV level in thallium 203 has been measured by means of XK â Îł coincidences. The experimental result PK = (1.5 ± 0.45) 10^-5agrees with the theory of Law and Campbell.L'ionisation interne K accompagnant l'Ă©mission ÎČ du mercure 203 alimentant le niveau de 279 keV du thallium 203 a Ă©tĂ© mesurĂ©e par coĂŻncidences X K â y. La valeur expĂ©rimentale trouvĂ©e PK = (1,5 ± 0,45) 10^-5est en accord avec la thĂ©orie de Law et Campbell
BANDES SATELLITES DES RAIES D'ĂLECTRONS DE CONVERSION INTERNE
Comparaison des bandes satellites expérimentales dans les
spectres de conversion interne avec les calculs théoriques, sur la base de
variations de l'énergie de liaison calculées, en fonction de la charge, par une
méthode H-F-S relativiste. Mesures comparatives de la période de l'état excité
de 59,5 keV du neptunium 237 dans le cas d'atomes peu et trĂšs
ionisés.Comparison of experimental satellite bands in conversion
electron spectra with theoretical calculations, based on the binding energy
variations calculated as a function of atom ionization with a relativistic
H-F-S method. Experimental relative measurements of a nuclear level period in
neptunium 237 have been performed in the cases of neutral and heavily charged
atoms
Dynamical effects on the way to fusion of very heavy nuclei
The central collision of 40Ar and 208Pb is studied considering the ellipsoidal deformations and isovector dipole mode of motion in the approaching phase. The collective energy dissipation is suggested to originate from the Fermi surface deformation which is treated as a kinematically independent mode of motion within the canonical Lagrange-Rayleigh dynamics. The possible extensions of the approach are discussed. The potential energy surface, calculated using the generalized (folded) surface potential, is studied. The saddle point in the potential energy surface lying at the border of strongly deformed compact configurations is located. The potential energy at this point is about 10MeV smaller than that of the ions touching each other in the spherical shape. The examination of trajectories followed by the system in its evolution shows that the inertia forces strongly hinder the motion of ions along the potential energy valley. The collective energy dissipated during the approach is found to be smaller than the difference in the potential energies at saddle point and at the touching configuration of unpolarized ions.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Construction of beta spectrum on the basis of experimental nuclear decay data
International audienceA computer code for -spectrum construction of 1300 radionuclei has been created. The tools use the experimental nuclear data adopted and compiled in the ENSDF file and experimental or estimated parameters of shape factors. The final uncertainty on the calculated -spectrum branch tries to deal with uncertainties on the radiation probability, the endpoint energy, and the shape factor parameters
Neutrons from spontaneous fission of longâlived superâ heavy nuclei
International audienceThe investigations of spontaneous fission of 268Db (Z = 105) have been performed. 268Db is the heaviest nuclide for which the average number of neutrons per spontaneous fission math = 4.2±1.0 was measured. The search for longâlived isotopes of superâheavy elements in nature is reconsidered. Presently the experiment SHIN in the underground low radioactivity laboratory in Modane (LSM) is going with high efficiency neutron detector to detect rare spontaneous fission events. © 2009 American Institute of Physic
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