23 research outputs found
Advancing Radiation-Detected Resonance Ionization towards Heavier Elements and More Exotic Nuclides
RAdiation-Detected Resonance Ionization Spectroscopy (RADRIS) is a versatile method for highly sensitive laser spectroscopy studies of the heaviest actinides. Most of these nuclides need to be produced at accelerator facilities in fusion-evaporation reactions and are studied immediately after their production and separation from the primary beam due to their short half-lives and low production rates of only a few atoms per second or less. Only recently, the first laser spectroscopic investigation of nobelium (Z=102) was performed by applying the RADRIS technique in a buffer-gas-filled stopping cell at the GSI in Darmstadt, Germany. To expand this technique to other nobelium isotopes and for the search for atomic levels in the heaviest actinide element, lawrencium (Z=103), the sensitivity of the RADRIS setup needed to be further improved. Therefore, a new movable double-detector setup was developed, which enhances the overall efficiency by approximately 65% compared to the previously used single-detector setup. Further development work was performed to enable the study of longer-lived (tâ/â>1 h) and shorter-lived nuclides (tâ/â<1 s) with the RADRIS method. With a new rotatable multi-detector design, the long-lived isotope 254Fm (tâ/â=3.2 h) becomes within reach for laser spectroscopy. Upcoming experiments will also tackle the short-lived isotope 251No (tâ/â=0.8 s) by applying a newly implemented short RADRIS measurement cycle
High-resolution laser system for the S3-Low Energy Branch
In this paper we present the first high-resolution laser spectroscopy results
obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in
preparation for the first experiments with the S-Low Energy Branch. Studies
of neutron-deficient radioactive isotopes of erbium and tin represent the first
physics cases to be studied at S. The measured isotope-shift and hyperfine
structure data are presented for stable isotopes of these elements. The erbium
isotopes were studied using the atomic transition (415 nm) and the tin isotopes were studied by
the atomic transition (286.4
nm), and are used as a benchmark of the laser setup. Additionally, the tin
isotopes were studied by the
atomic transition (811.6 nm), for which new isotope-shift data was obtained and
the corresponding field-shift and mass-shift factors are
presented
PremiÚre mesure des résonances géantes isoscalaires dans un noyau exotique riche en neutrons : le 68Ni avec la cible active Maya
The study of the Isoscalar Giant Monopole Resonance (ISGMR) and the Isoscalar Giant Quadrupole Resonance (ISGQR) in stable nuclei provided relevant information on both nuclear matter and nuclear structure in past decades. For instance the centroid of the ISGMR can be linked to the incompressibility modulus of the infinite nuclear matter. Values for exotic nuclei would help in constraining it. In unstable nuclei, only one measurement has been performed so far (56Ni) and in order to study the evolution of the ISGMR and the ISGQR along an isotopic chain, measurements in neutron-rich Ni are called for.To reach this goal, a dedicated experiment was performed at GANIL in Septembre 2010. A 68Ni beam at 50 AMeV and with an intensity of 10^4 pps has been produced on LISE beamline. The inelastic scattering of alpha (alpha, alphaâ) and deuteron particles (d,dâ) on 68Ni in inverse kinematics has been studied with the active target Maya. It is the first attempt to measure the ISGMR and ISGQR in an unstable neutron-rich nucleus. For each experiment, the excitation energy spectrum has been reconstructed and the angular distributions have been studied with two independant methods. Experimental differential cross sections have been compared to DWBA calculations using RPA transition density in order to deduce the properties of the states observed. Concerning the analysis in (alpha, alphaâ), the ISGMR is fragmented with a shoulder at 21.1+/-0.6 MeV, the ISGQR is concentred at 16.9+/-0.8 MeV and exhausted 61+/-17% of the Energy Weighted Sum Rule (EWSR). Moreover, a « soft GMR », predicted but never observed, is identified at 13.4+/-0.5 MeV. All these results are confirmed with the experiment in (d,dâ), with the exception of the ISGQR due to unadapted experimental conditions.LâĂ©tude des rĂ©sonances gĂ©antes monopolaires isoscalaires (ISGMR) et des rĂ©sonances gĂ©antes quadrupolaires isoscalaires (ISGQR) dans les noyaux stables, a permis dâobtenir ces derniĂšres dĂ©cennies des informations fondamentales sur la structure et la matiĂšre nuclĂ©aire. En particulier, le centroĂŻde de la ISGMR peut ĂȘtre reliĂ© au module dâincompressibilitĂ© de la matiĂšre nuclĂ©aire infinie. Des donnĂ©es dans les noyaux exotiques nous aideraient Ă contraindre ce module dâincompressibilitĂ©. Dans les noyaux instables, une seule mesure a, Ă lâheure actuelle, Ă©tĂ© rĂ©alisĂ©e (56Ni). Afin dâĂ©tudier lâĂ©volution de la ISGMR et de la ISGQR le long dâune chaĂźne isotopique, des mesures dans un noyau exotique riche en neutrons sont donc nĂ©cessaires.LâexpĂ©rience Ă©tudiĂ©e dans cette thĂšse a Ă©tĂ© rĂ©alisĂ©e au Grand AccĂ©lĂ©rateur National dâIons Lourds (GANIL) Ă Caen en septembre 2010. Un faisceau de 68Ni Ă 50 AMeV et dâune intensitĂ© de 10^4 pps a Ă©tĂ© produit et purifiĂ© sur la ligne LISE. Les rĂ©actions de diffusion inĂ©lastique de particules alpha (alpha, alphaâ) et de deutons (d,dâ) sur 68Ni en cinĂ©matique inverse ont Ă©tĂ© Ă©tudiĂ©es avec la cible active Maya. Il sâagit de la premiĂšre mesure de la ISGMR et de la ISGQR dans un noyau instable riche en neutrons.Pour chaque expĂ©rience, le spectre en Ă©nergie dâexcitation a Ă©tĂ© reconstruit et les distributions angulaires Ă©tudiĂ©es par deux mĂ©thodes indĂ©pendantes. Les sections efficaces expĂ©rimentales ont Ă©tĂ© comparĂ©es Ă celles issues de calculs DWBA utilisant des densitĂ©s de transition RPA. Lâanalyse en (alpha, alphaâ) a permis lâobservation dâune ISGMR fragmentĂ©e avec un Ă©paulement Ă 21.1+/-0.6 MeV, dâune ISGQR concentrĂ©e Ă 16.9+/-0.8 MeV qui Ă©puise 61+/-17% de la rĂšgle de somme pondĂ©rĂ©e en Ă©nergie (EWSR). De plus, un mode « soft GMR », prĂ©dit mais jamais observĂ©, a Ă©tĂ© identifiĂ© Ă 13.4+/-0.5 MeV. Tous ces rĂ©sultats sont confirmĂ©s par lâanalyse en (d,dâ), Ă lâexception de lâobservation de la ISGQR pour laquelle les conditions de fonctionnement nâĂ©taient pas favorables
First measurement of the isoscalar giant resonances in a neutron rich exotic nucleus (68Ni) using Maya active target
LâĂ©tude des rĂ©sonances gĂ©antes monopolaires isoscalaires (ISGMR) et des rĂ©sonances gĂ©antes quadrupolaires isoscalaires (ISGQR) dans les noyaux stables, a permis dâobtenir ces derniĂšres dĂ©cennies des informations fondamentales sur la structure et la matiĂšre nuclĂ©aire. En particulier, le centroĂŻde de la ISGMR peut ĂȘtre reliĂ© au module dâincompressibilitĂ© de la matiĂšre nuclĂ©aire infinie. Des donnĂ©es dans les noyaux exotiques nous aideraient Ă contraindre ce module dâincompressibilitĂ©. Dans les noyaux instables, une seule mesure a, Ă lâheure actuelle, Ă©tĂ© rĂ©alisĂ©e (56Ni). Afin dâĂ©tudier lâĂ©volution de la ISGMR et de la ISGQR le long dâune chaĂźne isotopique, des mesures dans un noyau exotique riche en neutrons sont donc nĂ©cessaires.LâexpĂ©rience Ă©tudiĂ©e dans cette thĂšse a Ă©tĂ© rĂ©alisĂ©e au Grand AccĂ©lĂ©rateur National dâIons Lourds (GANIL) Ă Caen en septembre 2010. Un faisceau de 68Ni Ă 50 AMeV et dâune intensitĂ© de 10^4 pps a Ă©tĂ© produit et purifiĂ© sur la ligne LISE. Les rĂ©actions de diffusion inĂ©lastique de particules alpha (alpha, alphaâ) et de deutons (d,dâ) sur 68Ni en cinĂ©matique inverse ont Ă©tĂ© Ă©tudiĂ©es avec la cible active Maya. Il sâagit de la premiĂšre mesure de la ISGMR et de la ISGQR dans un noyau instable riche en neutrons.Pour chaque expĂ©rience, le spectre en Ă©nergie dâexcitation a Ă©tĂ© reconstruit et les distributions angulaires Ă©tudiĂ©es par deux mĂ©thodes indĂ©pendantes. Les sections efficaces expĂ©rimentales ont Ă©tĂ© comparĂ©es Ă celles issues de calculs DWBA utilisant des densitĂ©s de transition RPA. Lâanalyse en (alpha, alphaâ) a permis lâobservation dâune ISGMR fragmentĂ©e avec un Ă©paulement Ă 21.1+/-0.6 MeV, dâune ISGQR concentrĂ©e Ă 16.9+/-0.8 MeV qui Ă©puise 61+/-17% de la rĂšgle de somme pondĂ©rĂ©e en Ă©nergie (EWSR). De plus, un mode « soft GMR », prĂ©dit mais jamais observĂ©, a Ă©tĂ© identifiĂ© Ă 13.4+/-0.5 MeV. Tous ces rĂ©sultats sont confirmĂ©s par lâanalyse en (d,dâ), Ă lâexception de lâobservation de la ISGQR pour laquelle les conditions de fonctionnement nâĂ©taient pas favorables.The study of the Isoscalar Giant Monopole Resonance (ISGMR) and the Isoscalar Giant Quadrupole Resonance (ISGQR) in stable nuclei provided relevant information on both nuclear matter and nuclear structure in past decades. For instance the centroid of the ISGMR can be linked to the incompressibility modulus of the infinite nuclear matter. Values for exotic nuclei would help in constraining it. In unstable nuclei, only one measurement has been performed so far (56Ni) and in order to study the evolution of the ISGMR and the ISGQR along an isotopic chain, measurements in neutron-rich Ni are called for.To reach this goal, a dedicated experiment was performed at GANIL in Septembre 2010. A 68Ni beam at 50 AMeV and with an intensity of 10^4 pps has been produced on LISE beamline. The inelastic scattering of alpha (alpha, alphaâ) and deuteron particles (d,dâ) on 68Ni in inverse kinematics has been studied with the active target Maya. It is the first attempt to measure the ISGMR and ISGQR in an unstable neutron-rich nucleus. For each experiment, the excitation energy spectrum has been reconstructed and the angular distributions have been studied with two independant methods. Experimental differential cross sections have been compared to DWBA calculations using RPA transition density in order to deduce the properties of the states observed. Concerning the analysis in (alpha, alphaâ), the ISGMR is fragmented with a shoulder at 21.1+/-0.6 MeV, the ISGQR is concentred at 16.9+/-0.8 MeV and exhausted 61+/-17% of the Energy Weighted Sum Rule (EWSR). Moreover, a « soft GMR », predicted but never observed, is identified at 13.4+/-0.5 MeV. All these results are confirmed with the experiment in (d,dâ), with the exception of the ISGQR due to unadapted experimental conditions
Study of ÂčâčC by One-Neutron Knockout
21st International Conference on Few-Body Problems in Physics, Chicago, IL, USA, May 18-22, 2015.The spectroscopic structure of ÂčâčC, a prominent one-neutron halo nucleus, has been studied with a ÂČâ°C secondary beam at 290 MeV/nucleon and a carbon target. Neutron-unbound states populated by the one-neutron knockout reaction were investigated by means of the invariant mass method. The preliminary relative energy spectrum and parallel momentum distribution of the knockout residue, ÂčâčCâ, were reconstructed from the measured four momenta of theÂčâžC fragment, neutron, and beam. Three resonances were observed in the spectrum, which correspond to the states at Ex = 0.62(9), 1.42(10), and 2.89(10) MeV. The parallel momentum distributions for the 0.62-MeV and 2.89-MeV states suggest spin-parity assignments of 5/2âș and 1/2â», respectively. The 1.42-MeV state is in line with the reported 5/22âș state
Advancing Radiation-Detected Resonance Ionization towards Heavier Elements and More Exotic Nuclides
RAdiation-Detected Resonance Ionization Spectroscopy (RADRIS) is a versatile method for highly sensitive laser spectroscopy studies of the heaviest actinides. Most of these nuclides need to be produced at accelerator facilities in fusion-evaporation reactions and are studied immediately after their production and separation from the primary beam due to their short half-lives and low production rates of only a few atoms per second or less. Only recently, the first laser spectroscopic investigation of nobelium (Z=102) was performed by applying the RADRIS technique in a buffer-gas-filled stopping cell at the GSI in Darmstadt, Germany. To expand this technique to other nobelium isotopes and for the search for atomic levels in the heaviest actinide element, lawrencium (Z=103), the sensitivity of the RADRIS setup needed to be further improved. Therefore, a new movable double-detector setup was developed, which enhances the overall efficiency by approximately 65% compared to the previously used single-detector setup. Further development work was performed to enable the study of longer-lived (t1/2>1 h) and shorter-lived nuclides (t1/2<1 s) with the RADRIS method. With a new rotatable multi-detector design, the long-lived isotope 254Fm (t1/2=3.2Â h) becomes within reach for laser spectroscopy. Upcoming experiments will also tackle the short-lived isotope 251No (t1/2=0.8Â s) by applying a newly implemented short RADRIS measurement cycle
Spectroscopy of 17C via one-neutron knockout reaction
A spectroscopic study of 17C was performed via the one-neutron knockout reaction of 18C on a carbon target at RIKEN-RIBF. Three unbound states at excitation energies of 2.66(2), 3.16(5), and 3.97(3) MeV (preliminary) were observed. The energies are compared with shell-model calculations and existing measurements to deduce their spin-parities. From the comparison, the states at 2.66(2) and 3.97(3) MeV are suggested to be 1/2â and 3/2â, respectively. From its decay property, the state at 3.16(5) MeV is indicated to be 9/2+