Isomeric states in 253^{253}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 $g_p$ 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 $g_p$ 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 $g_p$, the experimental studies of $g_p$, 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

Création de lacunes K lors d'une émission β de faible énergie : 203Hg → 203*Tl (279 keV)

The internal K ionization accompanying the β decay of mercury 203 feeding the 279 keV level in thallium 203 has been measured by means of XK — γ coincidences. The experimental result PK = (1.5 ± 0.45) 10^-5agrees with the theory of Law and Campbell.L'ionisation interne K accompagnant l'émission β du mercure 203 alimentant le niveau de 279 keV du thallium 203 a été mesurée par coïncidences X K — y. La valeur expérimentale trouvée PK = (1,5 ± 0,45) 10^-5est en accord avec la théorie de Law et Campbell

BANDES SATELLITES DES RAIES D'ÉLECTRONS 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 très 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 $\beta$-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 $\beta$-spectrum branch tries to deal with uncertainties on the radiation probability, the endpoint energy, and the shape factor parameters

Neutrons from spontaneous fission of long‐lived super‐ 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 long‐lived isotopes of super‐heavy 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