Search results for "ydinfysiikka"
showing 10 items of 542 documents
Charge breeding at GANIL: Improvements, results, and comparison with the other facilities
2019
International audience; The 1+/n+ method, based on an ECRIS charge breeder (CB) originally developed at the LPSC laboratory, is now implemented at GANIL for the production of Radioactive Ion Beams (RIBs). Prior to its installation in the middle of the low energy beam line of the SPIRAL1 facility, the 1+/n+ system CB has been modified based on the experiments performed on the CARIBU Facility at Argone National Laboratory. Later, it has been tested at the 1+/n+ LPSC test bench to validate its operation performances. Charge breeding efficiencies as well as charge breeding times have been measured for noble gases and alkali elements. The commissioning phase started at GANIL in the second half-y…
Quenching of gA deduced from the β-spectrum shape of 113Cd measured with the COBRA experiment
2020
A dedicated study of the quenching of the weak axial-vector coupling strength gA in nuclear processes has been performed by the COBRA collaboration. This investigation is driven by nuclear model calculations which show that the β-spectrum shape of the fourfold forbidden non-unique decay of 113Cd strongly depends on the effective value of gA. Using an array of CdZnTe semiconductor detectors, 45 independent 113Cd spectra were obtained and interpreted in the context of three nuclear models. The resulting effective mean values are g‾A(ISM)=0.915±0.007, g‾A(MQPM)=0.911±0.013 and g‾A(IBFM-2)=0.955±0.022. These values agree well within the determined uncertainties and deviate significantly from th…
Katsaus Suomen varhaiseen atomihistoriaan
2022
Nykyisellä ydinteknologialla on lähinnä kaksi haaraa joita ovat ydinenergia ja lääketieteellinen isotooppitekniikka. Ensin mainitun lähtölaukauksena Suomessa pidetään nk. energiakomitean perustamista vuonna 1955. Tämän historian tutkimuksen painopiste on ollut 1960-ja 1970-luvun tapahtumissa, jotka liittyvät nykyisten ydinvoimalaitosten hankintakuvioihin. Professori Lennart Simons aloitti vakavasti otettavan ydinfysiikan tutkimuksen Suomessa ja oli alan ykkösnimi 1940- ja 1950-luvuilla kun koko länsimaailman yli pyyhkäisi atomiteknologian huuma, jota ehkä voi sanoa ensimmäiseksi teknologiahypeksi modernissa mielessä. Kirjan tarkoituksena on antaa lisävalaistusta suomalaisen ydinteknologian …
Offline commissioning of a new gas cell for the MARA Low-Energy Branch
2023
Results of offline commissioning tests for a new dedicated gas cell for the Mass Analysing Recoil Apparatus (MARA) Low-Energy Branch are reported. Evacuation time, ion survival and transport efficiency in helium buffer gas were characterized with a radioactive 223Ra 𝛼-recoil source. Suppression of the ion signal, originating from non-neutralized species in the gas cell, was explored with 219Rn ions, the daughter recoil of 223Ra, as a function of voltage applied to one of the ion-collector electrodes. Two-step laser resonance ionization of stable tin isotopes produced inside the gas cell from a heated bronze filament was demonstrated, and broadening of the atomic resonances in argon buffer …
Variation of fundamental constants and 229Th
2017
The first excited state of the nucleus229Th has an exceptionally small excitation energy of7.8 eV, which is expected to be very sensitive to changes in the fine structure constant α.A small difference in the Coulomb energies of the two states, which both are of the order109eV, would amplify variations in α into large variations of the transition frequency.Hartree-Fock and Hartree-Fock-Bogoliubov calculations are performed to compute theCoulomb energies of the two states. The kinetic energies are also calculated which reflecta possible variation in the nucleon or quark masses or local Lorentz invariance violation. peerReviewed
Population of lead isotopes in binary reactions using a Rb 94 radioactive beam
2020
8 pags., 9 figs.
Lifetimes of core-excited states in semi-magic $^{95}$Rh
2020
Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus 95Rh. The fusion-evaporation reaction 58Ni(40Ca,3p) was used to populate high-spin states in 95Rh at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6mg/cm2 metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations. peerReviewed
Evidence of oblate-prolate shape coexistence in the strongly-deformed nucleus 119Cs
2021
International audience; Prolate-oblate shape coexistence close to the ground state in the strongly-deformed proton-rich A≈120 nuclei is reported for the first time. One of the four reported bands in 119Cs, built on a 11/2− state at 670 keV, consists of nearly degenerate signature partners, and has properties which unequivocally indicate the strongly-coupled πh11/2[505]11/2− configuration associated with oblate shape. Together with the decoupled πh11/2[541]3/2− band built on the 11/2− prolate state at 110 keV, for which a half-life of T1/2=55(5)μs has been measured, the new bands bring evidence of shape coexistence at low spin in the proton-rich strongly deformed A≈120 nuclei, a phenomenon p…
Isovector and isoscalar spin-multipole giant resonances in the parent and daughter nuclei of double-β-decay triplets
2022
The strength distributions, including giant resonances, of isovector and isoscalar spin-multipole transitions in the commonly studied double-β-decay triplets are computed in the framework of the quasiparticle random-phase approximation (QRPA) using the Bonn-A two-body interaction in no-core single-particle valence spaces. The studied nuclei include the double-β parent and daughter pairs (76Ge, 76Se), (82Se, 82Kr), (96Zr, 96Mo), (100Mo, 100Ru), (116Cd, 116Sn), (128Te, 128Xe), (130Te, 130Xe), and (136Xe, 136Ba). The studied transitions proceed from the ground states to the Jπ=0−,1−,2− (spin-dipole transitions) and Jπ=1+,2+,3+ (spin-quadrupole transitions) excited states in these nuclei. Compa…
Characterizing the initial conditions of heavy-ion collisions at the LHC with mean transverse momentum and anisotropic flow correlations
2022
Physics letters / B 834, 137393 (2022). doi:10.1016/j.physletb.2022.137393