H. Savajols

H. Savajols
Grand Accélérateur National d'Ions Lourds | GANIL · Physics

About

223
Publications
12,089
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3,353
Citations
Citations since 2017
18 Research Items
1087 Citations
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2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200

Publications

Publications (223)
Article
The properties of nuclei with extreme neutron–to–proton ratios, far from those naturally occurring on Earth, are key to understand nuclear forces and how nucleons hold together to form nuclei. ⁷H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron–to–proton ratio known so far. However, its sheer existence...
Article
Full-text available
The Super Separator Spectrometer S3 is, with the NFS (Neutrons For Science) facility, a major experimental system developed for SPIRAL2. It is designed for very low cross section experiments at low (<15MeV/u) energy. It will receive the very high intensity (more than 1pμA) stable ion beams accelerated by the superconducting LINAG accelerator of SPI...
Article
An inelastic α-scattering experiment on the unstable N=Z, doubly-magic 56Ni nucleus was performed in inverse kinematics at an incident energy of 50 A.MeV at GANIL. High multiplicity for α-particle emission was observed within the limited phase-space of the experimental setup. This observation cannot be explained by means of the statistical-decay mo...
Preprint
Full-text available
An inelastic $\alpha$-scattering experiment on the unstable $N=Z$, doubly-magic $^{56}$Ni nucleus was performed in inverse kinematics at an incident energy of 50 A.MeV at GANIL. High multiplicity for $\alpha$-particle emission was observed within the limited phase-space of the experimental setup. This observation cannot be explained by means of the...
Article
The novel and sensitive In-Gas Laser Ionization Spectroscopy (IGLIS) technique enables high-precision laser spectroscopy of the heaviest elements and isotopes very far from stability that are produced in fusion-evaporation reactions at in-flight separators. Powerful and dedicated laser systems are required in these facilities to realize in-gas jet...
Article
Full-text available
The properties of nuclei with extreme neutron–to–proton ratios reveal the limitations of state-ofthe-art nuclear models and are key to understand nuclear forces. 7H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron–to–proton ratio ever known, but its sheer existence and properties are still a challenge f...
Article
Full-text available
The analysis of fission events following the implantation of evaporation residues produced in the fusion reaction of 50Ti and 209Bi at different bombarding energies has revealed 5 millisecond decays, which are attributed to the spontaneous fission of proton-evaporation channels. The average cross sections for proton evaporation are found to be ∼100...
Article
Full-text available
The superheavy isotope ²⁵⁸Db was produced in the ²⁰⁹Bi(⁵⁰Ti, 1n)²⁵⁸Db reaction at GSI, Germany. A detailed \( \alpha\)-spectroscopy study of this isotope and its \( \alpha\)-decay daughter products was performed. Two long-lived \( \alpha\)-decaying states in ²⁵⁸Db are observed. A spin-parity of \( 0^{-}\) is tentatively assigned to the ground state...
Conference Paper
The monitoring of targets under irradiation was investigated using a 20 keV electron beam. An integrated and automated electron beam deflection was developed allowing a monitoring over the whole surface of target materials. Thus, local defects could be identified on-line during an experiment performed at GANIL involving different materials irradiat...
Article
The systematic study of fission fragment yields under different initial conditions has provided valuable experimental data for benchmarking models of fission product yields. Nuclear reactions using inverse kinematics coupled to the use of a high-resolution spectrometer with good fragment identification are shown here to be a powerful tool to measur...
Article
Full-text available
Cross sections and corresponding momentum distributions have been measured for the first time at zero degrees for the exotic nuclei obtained from a beam of ¹⁸O at 8.5 MeV/A impinging on a 1 mg/cm²²³⁸U target. Sizable cross sections were found for the production of exotic species arising from the neutron transfer and proton removal from the projecti...
Article
A compact silicon detector array with high spatial granularity and fast, fully digital data recording has been developed and commissioned for the investigation of heavy and superheavy nuclear species. The detector array can be combined in close geometry with large volume germanium detectors. It offers comprehensive particle and photon coincidence a...
Article
Full-text available
The in-gas laser ionization and spectroscopy (IGLIS) technique was applied on the Ac212–215 isotopes, produced at the Leuven Isotope Separator On-Line (LISOL) facility by using the in-gas-cell and the in-gas-jet methods. The first application under on-line conditions of the in-gas-jet laser spectroscopy method showed a superior performance in terms...
Article
Full-text available
Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we d...
Article
Full-text available
The systematic study of fission fragment yields under different initial conditions provides a valuable experimental benchmark for fission models that aim to understand this complex decay channel and to predict reaction product yields. Inverse kinematics coupled to the use of a high-resolution spectrometer is shown to be a powerful tool to identify...
Article
The first measurement of the one-neutron transfer reaction 11Li(p,d)10Li performed using the IRIS facility at TRIUMF with a 5.7AMeV11Li beam interacting with a solid H2 target is reported. The 10Li residue was populated strongly as a resonance peak with energy Er=0.62 ±0.04MeV having a total width $\Gamma$ = 0.33 ±0.07MeV. The angular distribution...
Article
Full-text available
The first measurement of the one-neutron transfer reaction 11Li(p,d)10Li performed using the IRIS facility at TRIUMF with a 5.7A MeV 11Li beam interacting with a solid H2 target is reported. The 10Li residue was populated strongly as a resonance peak with energy Er=0.62±0.04 MeV having a total width Γ=0.33±0.07 MeV. The angular distribution of this...
Article
To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by...
Article
The Super Separator Spectrometer (S3S3) facility is developed in the framework of the SPIRAL2 project [1]. S3S3 has been designed to extend the capability of the facility to perform experiments with extremely low cross sections, taking advantage of the very high intensity stable beams of the superconducting linear accelerator of SPIRAL2. It will ma...
Article
Full-text available
The Isoscalar Giant Monopole Resonance (ISGMR) and the Isoscalar GiantDipole Resonance (ISGDR) compression modes have been studied in thedoubly-magic unstable nucleus 56Ni. They were measured by inelastic α-particlescattering in inverse kinematics at 50 MeV/u with the MAYA active targetat the GANIL facility. The centroid of the ISGMR has been obtai...
Article
Isoscalar giant resonances have been measured in the unstable Ni68 nucleus using inelastic alpha and deuteron scattering at 50A MeV in inverse kinematics with the active target MAYA at GANIL. Using alpha scattering, the extracted isoscalar giant monopole resonance (ISGMR) centroid was determined to be 21.1±1.9 MeV and the isoscalar giant quadrupole...
Article
Full-text available
The structure of the F 24 nucleus has been studied at GANIL using the β decay of O 24 and the in-beam γ -ray spectroscopy from the fragmentation of Na 27, 28, Ne, 25, 26 and Mg 29, 30 nuclei. Combining these complementary experimental techniques, the level scheme of F 24 has been constructed up to 3.6 MeV by means of particle- γ and particle- γ γ c...
Article
The Super Separator Spectrometer S 3 is a major experimental system developed for SPIRAL2. It has been designed for physics experiments with very low cross sections by taking full advantage of the very high intensity stable beams to be produced by LINAG, the superconducting linear accelerator at GANIL. These intensities will open new opportunities...
Article
Full-text available
The first conclusive evidence of a dipole resonance in 11 Li having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03 Æ 0.03 MeV with a width of 0.51 Æ...
Article
Full-text available
The structure of the $^{24}$F nucleus has been studied at GANIL using the $\beta$ decay of $^{24}$O and the in-beam $\gamma$-ray spectroscopy from the fragmentation of projectile nuclei. Combining these complementary experimental techniques, the level scheme of $^{24}$F has been constructed up to 3.6 Mev by means of particle-$\gamma$ and particle-$...
Article
Full-text available
The isoscalar monopole response has been measured in the unstable nucleus ^{68}Ni using inelastic alpha scattering at 50A MeV in inverse kinematics with the active target MAYA at GANIL. The isoscalar giant monopole resonance (ISGMR) centroid was determined to be 21.1±1.9 MeV and indications for a soft monopole mode are provided for the first time a...
Article
A new segmented silicon-array called MUSETT has been built for the study of heavy elements using the Recoil-Decay-Tagging technique. MUSETT is located at the focal plane of the VAMOS spectrometer at GANIL and is used in conjunction with a gamma-ray array at the target position. This paper describes the device, which consists of four 10 x 10 cm(2) S...
Article
Full-text available
The structure of the nucleus 25F was investigated through in-beam {\gamma}-ray spectroscopy of the fragmentation of 26Ne and 27,28Na ion beams. Based on the particle-{\gamma} and particle-{\gamma}{\gamma} coincidence data, a level scheme was constructed and compared with shell model and coupled-cluster calculations. Some of the observed states were...
Article
The focal plane of S-3 (Super Separator Spectrometer), a new experimental area of SPIRAL2 at GANIL, will be used for identification of nuclei, and requires the reconstruction of their trajectories and velocities by the Time Of Flight (TOF) method. Classical tracking detectors used in-beam would generate a lot of angular and energy straggling due to...
Article
Full-text available
In-gas-cell laser ionization spectroscopy studies on the neutron deficient 97-101Ag isotopes have been performed with the LISOL setup. Magnetic dipole moments and mean-square charge radii have been determined for the first time with the exception of 101Ag, which was found in good agreement with previous experimental values. The reported results all...
Article
Full-text available
The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using the MUST2 Si-CsI array in order to shed light on the level structure of 9He. The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was used as a test to validate the experimental methods. The 9He missing mass spectrum was deduced from the kinetic energie...
Article
Full-text available
Two fission experiments have been performed at GANIL using U-238 beams at different energies and light targets. Different fissioning systems were produced with centre of mass energies from 10 to 240 MeV and their decay by fission was investigated with GANIL spectrometers. Fission-fragment isotopic distributions have been obtained. The evolution wit...
Article
Full-text available
The inelastic α-scattering experiment on 56Ni in inverse kinematics was performed at an incident energy of 50 MeV/u at GANIL. A very high multiplicity for α-particle emission was observed with our phase-space limited experimental set-up. The maximum observed multiplicity, which cannot be explained by means of the statistical decay model, amounted t...
Article
Full-text available
Inverse kinematics coupled to a high-resolution spectrometer is used to investigate the isotopic yields of fission fragments produced in reactions between a 238U beam at 24 MeV/u and 9Be and 12C targets. Mass, atomic number and isotopic distributions are reported for the two reactions. These informations give access to the neutron excess and the is...
Article
The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse e...
Article
Full-text available
During the fission process, the nucleus deforms and elongates up to the two fragments inception and their final separation at scission deformation. The evolution of the nucleus energy with deformation is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus. The fiss...
Article
The structure of nucleus F-25 was studied by use of in-beam gamma-ray spectroscopy of the fragmentation of a S-36 beam. The emitted gamma rays were detected by BaF2 detectors. In the gamma-ray spectrum obtained a wide bump between 3 and 4.5 MeV energy was observed corresponding to a set of gamma rays, including their first and second escape peaks....
Article
Full-text available
We present precision Penning trap mass measurements of neutron-rich calcium and potassium isotopes in the vicinity of neutron number N=32. Using the TITAN system, the mass of 51K was measured for the first time, and the precision of the (51,52)Ca mass values were improved significantly. The new mass values show a dramatic increase of the binding en...
Article
Full-text available
Two fission experiments have been performed at GANIL using U-238 beams at different energies and light targets. Different fissioning systems were produced with excitation energies from 10 to 230 MeV and their decay by fission was investigated with GANIL spectrometers. Preliminary fission-fragment isotopic distributions have been obtained. The evolu...
Article
Two fission experiments have been performed at GANIL using 238U beams at different energies and light targets. Different fissioning systems were produced with centre of mass energies from 10 to 240 MeV and their decay by fission was investigated with GANIL spectrometers. Preliminary fission-fragment isotopic distributions have been obtained. The ev...
Article
The Super Separator Spectrometer (S3) will receive the very high intensity heavy ion beams from the LINAG accelerator of SPIRAL2. Its privileged fields of physics are the delayed study of rare nuclei and secondary reactions with exotic nuclei. The project is presently in a phase of conceptual design. It includes a rotating target to sustain the hig...
Article
Full-text available
The structure of the weakly bound 926F17 odd-odd nucleus, produced from 27,28Na nuclei, has been investigated at GANIL by means of the in-beam γ-ray spectroscopy technique. A single γ-line is observed at 657(7) keV in 926F which has been ascribed to the decay of the excited J=2+ state to the J=1+ ground state. The possible presence of intruder nega...
Article
Full-text available
We present Penning-trap mass measurements of neutron-rich 44,47-50K and 49,50Ca isotopes carried out at the TITAN facility at TRIUMF-ISAC. The 44K mass measurement was performed with a charge-bred 4+ ion utilizing the TITAN EBIT, and agrees with the literature. The mass excesses obtained for 47K and 49,50Ca are more precise and agree with the value...
Article
Full-text available
The Super Separator Spectrometer S-3 is a device designed for experiments with the very high intensity stable ion beam of the superconducting linear accelerator of the SPIRAL2 facility. Its Physics goals cover the study of radioactive ions produced by fusion-evaporation reactions, like superheavy elements or neutron deficient nuclei close to the pr...
Article
The unbound nucleus 12Li is evaluated by studying three-neutron one-proton excitations within the multistep shell model in the complex energy plane. It is found that the ground state of this system consists of an antibound 2− state. A number of narrow states at low energy are found which ensue from the coupling of resonances in 11Li to continuum st...
Article
Full-text available
In order to solve the nature of 9 He ground state, additional information on this unbound nucleus with extreme N/Z ratio was needed. The present study was performed via the (d,p) reaction, a standard tool for determination of neutron single-particle distribution.
Article
The MAYA detector is a Time-Charge Projection Chamber based on the concept of active target. These type of devices use a part of the detection system, the filling gas in this case, in the role of reaction target. The MAYA detector performs three-dimensional tracking, in order to determine physical observables of the reactions occurring inside the d...
Article
S(3) (Super Separator Spectrometer) is a device designed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams, which will provide ions with A/Q = 3 in SPIRAL2 phase one, can reach intensities up to 1mA for light ions, A<50. T...
Article
Full-text available
S3 (Super Separator Spectrometer) [1] is a future device designed for experiments with the high intensity heavy ion stable beams of SPIRAL2 [2] at GANIL (Caen, France). It will include a target resistant to these very high intensities, a first stage momentum achromat for primary beam extraction and suppression, a second stage mass spectrometer and...
Article
Full-text available
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state...
Article
Full-text available
The unbound nucleus $^{12}$Li is evaluated by using the multistep shell model in the complex energy plane assuming that the spectrum is determined by the motion of three neutrons outside the $^9$Li core. It is found that the ground state of this system consists of an antibound $1/2^+$ state and that only this and a $1/2^-$ and a $5/2^+$ excited sta...
Article
A compact, quasi-4π position sensitive silicon array, TIARA, designed to study direct reactions induced by radioactive beams in inverse kinematics is described here. The Transfer and Inelastic All-angle Reaction Array (TIARA) consists of 8 resistive charge division detectors forming an octagonal barrel around the target and a set of double-sided si...
Article
S' (Super Separator Spectrometer) is a. device designed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams call reach intensities exceeding 100p mu A for lighter ions. These unprecedented intensities open new opportunities...
Article
A global optical model potential (GDP08) for {sup 3}He projectiles has been obtained by simultaneously fitting the elastic scattering data of {sup 3}He from targets of 40{<=}A{sub T}{<=}209 at incident energies of 30{<=}E{sub inc}{<=}217 MeV. Uncertainties and correlation coefficients between the global potential parameters were obtained by using t...
Article
Phys. Rev. Lett. in press (4 pages, 3 figures), Expérience GANIL/SPIRAL
Article
Full-text available
A general experimental technique for high resolution studies of nucleon transfer reactions using radioactive beams is briefly described, together with the first new physics results that have been obtained with the new TIARA array. These first results from TIARA are for the reaction 24Ne(d,p)25Ne, studied in inverse kinematics with a pure radioactiv...
Article
One of the first fusion–evaporation experiments using radioactive ion beams was performed at GANIL in order to study proton-rich nuclei of the light rare-earth region. The low production cross-section of the exotic species of interest, in combination with the low intensity of the beam and its induced background, demanded the use of a highly efficie...
Article
Active targets are perfect tools for the study of reactions induced by radioactive ion beams of very low intensity. Thus, they make possible the study of direct and compound reactions at the same time. In this talk, we will present the results obtained with the MAYA active target for low energy reactions induced by the halo nucleus 11Li. A method u...