Post-accelerated Radioactive Beams Research Articles

Reaction dynamics and nuclear structure of light exotic nuclei

The paper discusses reaction experiments with low energy post-accelerated radioactive beams that investigated the role of halo structure and neutron excess on the reaction dynamics. Reactions induced by neutron-halo and proton-halo are compared and the dissimilarities in the reaction dynamics emerging from the differences in the nuclear structure are analysed. The case of neutron-rich nuclei is also discussed in particular the presence of resonances in the elastic scattering excitation function arising from the extended surface layer characteristic of these nuclei.

An innovative Superconducting Recoil Separator for HIE-ISOLDE

The ISOLDE Scientific Infrastructure at CERN offers a unique range of post-accelerated radioactive beams. The scientific program can be improved with the “Isolde Superconducting Recoil Separator” (ISRS), an innovative spectrometer able to deliver unprecedented (A, Z) resolution. In this paper we present an overview of the physics and ongoing technical developments.

Latest improvements of the SPIRAL1 facility at GANIL

Since 2001, the SPIRAL1 facility has been providing post-accelerated radioactive beams by the ISOL method. Over the last decade, SPIRAL1 has been improved to provide beams of condensable elements, by using a combination of a FEBIAD-type ion source (to produce 1+ ions) and a PHOENIX ECR charge breeder (to transform 1+ ions into N+ ions for post-acceleration). Both these elements have been improved in recent years: the FEBIAD source has been upgraded to improve its efficiency and reliability over time and the charge breeder was modified to extend the range of available charge states. In addition, a krypton beam was recently sent in a FEBIAD target ion-source system (TISS), allowing to produce medium mass radioactive 1+ ions that had not been previously produced in SPIRAL1. This papers compiles recent results illustrating the gain in performances and beam offer at SPIRAL1.

Highlights of the ISOLDE facility and the HIE-ISOLDE project

The ISOLDE facility is an ISOL-based radioactive beam facility at CERN. It is dedicated to the production and research of nuclei far from stability. Exotic nuclei of variety of chemical elements are available for the study of nuclear structure, nuclear astrophysics, fundamental symmetries and atomic physics, as well as for applications in condensed-matter and life sciences. Since longer than a decade it has offered the largest variety of post-accelerated radioactive beams in the world. In order to broaden the scientific opportunities beyond the present ISOLDE facility, the on-going HIE-ISOLDE (High Intensity and Energy) project will provide major improvements in energy range, beam intensity and beam quality. The first phase will boost the beam energy of the current REX LINAC to 5.5MeV/u resulting in larger cross sections for Coulomb excitation compared to the previous maximum energy of 3MeV/u. Higher energies will also open up many transfer reaction channels. Physics with post-accelerated beams starts in autumn 2015. The second phase of the project is already approved and is expected to be completed in 2018 allowing beam energies up to 10MeV/u for A/q=4.5. In this contribution the present status of the ISOLDE facility including some highlights will be discussed. The HIE-ISOLDE project will be described together with a panorama of the physics cases to be addressed.

Highlights of the ISOLDE facility and the HIE-ISOLDE Project

The ISOLDE Radioactive Beam Facility is the dedicated CERN installation for the production and acceleration of radioactive nuclei far from stability. Exotic nuclei of most chemical elements are available for the study of nuclear structure, nuclear astrophysics, fundamental symmetries and atomic physics, as well as for applications in condensed-matter and life sciences. Since more than a decade it offers the largest variety of post-accelerated radioactive beams in the world today. In order to broaden the scientific opportunities beyond the reach of the present facility, the on-going HIE-ISOLDE (High Intensity and Energy) project will provide major improvements in energy range, beam intensity and beam quality. Post-accelerated beams will be available already this year boosting the beam energy of the current REX LINAC to 4.3 MeV/u reaching 5.5 MeV/u next spring. In this new energy regime the Coulomb excitation cross sections are strongly increased with respect to the previous energy of bearly 3 MeV/u and many transfer reaction channels will open. The second stage of the energy upgrade will allow energies of the beam up to 10 MeV/u for the worst scenario of A/q = 4.5. The funds are already secured and it is expected to be completed in 2017. In this contribution the present status of the ISOLDE facility will be discussed, some highlights will be briefly described to illustrate the advances of the facility. The HIEISOLDE project will be described together with a panorama of the physics cases to be addressed in the near future with emphasis in the day-one experiment to be done this year.

Highlights of the ISOLDE Facility and the HIE-ISOLDE Project

The ISOLDE Radioactive Beam Facility is the dedicated CERN installation for the production and acceleration of radioactive nuclei far from stability. Exotic nuclei of most chemical elements are available for the study of nuclear structure, nuclear astrophysics, fundamental symmetries and atomic physics, as well as for applications in condensed-matter and life sciences. Since more than a decade it offers the largest variety of post-accelerated radioactive beams in the world today. In order to broaden the scientific opportunities beyond the reach of the present facility, the on-going HIE-ISOLDE (High Intensity and Energy) project will provide major improvements in energy range, beam intensity and beam quality. Post-accelerated beams will be available already this year boosting the beam energy of the current REX LINAC to 4.3 MeV/u reaching 5.5 MeV/u next spring. In this new energy regime the Coulomb excitation cross sections are strongly increased with respect to the previous energy of bearly 3 MeV/u and many transfer reaction channels will open. The second stage of the energy upgrade will allow energies of the beam up to 10 MeV/u for the worst scenario of A/q = 4.5. The funds are already secured and it is expected to be completed in 2017. In this contribution the present status of the ISOLDE facility will be discussed, some highlights will be briefly described to illustrate the advances of the facility. The HIEISOLDE project will be described together with a panorama of the physics cases to be addressed in the near future with emphasis in the day-one experiment to be done this year.

New subshell closure atN=58emerging in neutron-rich nuclei beyondNi78

The structure of neutron-rich nuclei beyond $^{78}\mathrm{Ni}$ was studied using postaccelerated radioactive beams of $^{83,84,85}\mathrm{Ga}$ utilizing $\ensuremath{\beta} \ensuremath{\gamma}$ and $\ensuremath{\beta}\ensuremath{-}n \ensuremath{\gamma}$ spectroscopy. Our data, when combined with energy level systematics, suggests a possible new spherical subshell closure at $N=58$ is created by the nearly degenerated $\ensuremath{\nu}3{s}_{1/2}$ and $\ensuremath{\nu}2{d}_{5/2}$ orbitals being well separated from other orbitals above $N=50$. The near degeneracy of these states could be evidenced by isomerism in this region. The energies of the ${2}_{1}^{+}$ and proposed ${4}_{1}^{+}$ states observed in $N=52$ $^{84}\mathrm{Ge}$ are interpreted as an indication of a possible weakening of the doubly magic $^{78}\mathrm{Ni}$ core for nuclei beyond $N=50$. The experimental evidence is supported by spherical HFB calculations using the ${\mathrm{SkO}}_{T}$ functional involving the tensor term in the nucleon-nucleon interaction.

Application of a thin double-sided microstrip detector for the registration of [formula omitted]-delayed charge particles: The 6He [formula omitted] decay into the two-body continuum of 6Li

We present a method for the detection of charged particles, emitted following β decay, that allows to reduce the background due to β radiation and thus to facilitate separation of the delayed-particle events. The isotopes of interest are implanted into a highly segmented double-sided silicon strip detector, resulting in excellent precision on the overall normalisation. The characteristics of the detector and the particle signatures are discussed. This method can be applied to a variety of systems close to the proton and neutron driplines; a region which the recent availability of post-accelerated radioactive beams has opened up for study. To demonstrate this, we measured the branching ratio of 6He β decay into the α + d two-body continuum of 6Li. We obtained a value of ( 1.7 ± 0.4 ) × 10 - 6 for energies α + d above 525 keV.

Rex-isolde—Post-accelerated radioactive beams at cern-isolde

The ISOLDE facility at CERN has been producing a broad range of radioactive beams for more than 30 years. The present low-energy beams (60 keV) of ISOLDE will soon be complemented by a post-accelerator, REX-ISOLDE, currently under construction. A novel scheme of trapping, cooling and charge-state breeding has been devised, which allows for a short, cost-effective LINAC reaching 0.8 - 2.2 MeV/u. The original physics aim of the REX-ISOLDE experiment is to probe the weakening of the magic numbers N=20,28 when going to extremely neutron-rich species by Coulomb excitation and neutron transfer reactions. For this purpose, a highly efficient Ge-detector array will be used, the MINIBALL. A number of other experiments are as well approved or planned.