Physics opportunities with the SPIRAL upgrade

8 févr. 2016, 13:30 → 10 févr. 2016, 15:00 Europe/Paris

This workshop aims at discussing the physics opportunities that will soon become available at SPIRAL 1 thanks to the progresses of the current upgrade.

First Circular SPIRAL_1_upgrade_WS_first_circular.pdf

List of intensities List_of_RIB_intensities.pdf

lundi 8 février

13:30 → 14:00 Registration

Registration

14:00 → 15:40 Status of the upgrade

14:00 Welcome address

Orateur: Dr Marek Lewitowicz (GANIL)

14:10 Introduction

Orateur: Dr Pierre DELAHAYE (GANIL)

14:15 SPIRAL 1 upgrade overview

Orateurs: Dr Laurent Maunoury (CNRS GANIL), M. Mickael Dubois

14:50 Day 1 beams

Orateur: Dr Pierre DELAHAYE (GANIL)

15:15 Performances of the SPIRAL1 charge breeder

In the framework of the SPIRAL1 upgrade under progress at the GANIL lab, the charge breeder based on a LPSC Phoenix ECRIS, first tested at ISOLDE [1] has been modified as to benefit of the last enhancements of this device from the 1+ / n+ community [2]. Prior to its installation in the midst of the low energy beam line of the SPIRAL1 facility, it has been tested at the 1+/n+ LPSC test bench to evaluate its performances and investigate the future operational modes. This contribution shall sum up the results obtained at LPSC concerning the 1+ to n+ conversion efficiencies for noble gazes as well as for alkali elements and the corresponding transformation times. [1] P. Delahaye et al, Review of Scientific Instruments. 77, 03B105 (2006) [2] R. Vondrasek et al, Review of Scientific Instruments 83 113303 (2012)

Orateur: Dr Laurent Maunoury (CNRS GANIL)

15:40 → 16:10 Coffee break

16:10 → 18:10 Future opportunities

16:10 Ongoing R&D on target - ion source systems

Orateur: Dr Pascal Jardin

16:45 New targets

Orateur: M. Olivier Bajeat

17:10 ISOL R&D at ISOLDE

Orateur: Dr João Pedro Ramos

17:45 Discussion

mardi 9 février

09:00 → 10:30 DESIR Physics

09:00 Fusion-evaporation reaction at SPIRAL1

Heavy ion beams from CSS1 allow to produce proton-rich ions via fusion-evaporation reactions. Different heat resistant targets would be bombarded with beams of about 6 MeV/A. This would allow to send these proton-rich nuclei to DESIR and to CIME for acceleration. In the talk, calculated production rate will be presented.

Orateur: M. Bertram Blank (CEN Bordeaux-Gradignan)

09:30 Precision measurements in mirror beta decays

In this contribution, we propose to measure the beta-neutrino angular correlation parameters in mirror beta decays using an upgraded LPCTrap setup at LIRAT. The main interest lies in the determination of Vud which can be deduced from this set of transitions if the GT/F mixing ratios are precisely known. This is precisely the purpose of the proposed measurements. The setup also provides the charge state distributions of the recoiling ions, enabling to study the atomic processes involved in these ions when the electron cloud is disturbed. The most interesting nuclei will be highlighted, among the new beams produced at SPIRAL1.

Orateur: Prof. Etienne Liénard (LPC Caen)

10:00 Studies of Superallowed Fermi Beta Emitters Using the IBE Decay Station

The study of superallowed Fermi β transitions between nuclear isobaric analog states of spin Jπ​ = 0+​ provides demanding, and fundamental, tests of the properties of the electroweak interaction. In particular, high-precision measurements of the β-decay ft values for superallowed Fermi β emitters with isospin T = 1 have been used to validate the conserved vector current (CVC) hypothesis to better than 12 parts in 10^5​ and provide the most precise determination of Vud, by far the most precisely determined element of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. Much current interest lies in the set of superallowed decays with Tz =−1 parents, as the isospin symmetry breaking corrections are, in general, larger than those for the Tz = 0 parents of the same mass due to an increased radial-overlap mismatch between the proton and neutron wave functions in the parent and daughter nuclei. However, high-precision measurements of the ft values for these decays are, in general, more challenging than for the Tz = 0 parents, due both to the fact that they are further from stability, and their daughter nuclei are in general also β unstable and give rise to unwanted but unavoidable time-dependent β-decay backgrounds. Recent experimental efforts, in combination with extensive simulation work, have, however, demonstrated that these challenges can be overcome. At the IBE low-energy decay station, a program to investigation Tz=−1 superallowed Fermi β emitters has been previously established. The setup uses a moving tape collection system and couples a plastic scintillator with a precisely calibrated HPGe to perform both half-life and branching ratio experiments simultaneously. Possible experiments for those superallowed emitters that are, or are expected to be, available at SPIRAL1 with sufficient intensity and purity will be discussed. This talk will highlight the complementarity of this program with similar studies performed at LISE, ISOLDE, and TRIUMF as well as the decays of T=1/2 mirror nuclei at LPCTrap.

Orateur: Dr Alex Laffoley (GANIL)

10:30 → 11:00 Coffee break

11:00 → 12:20 DESIR Physics

11:00 Mass measurements of light neutron-rich nuclei with SPIRAL1 beams

Mass spectrometry of short-lived neutron-rich nuclei give access to observables like 2n separation energies, which are sensitive to nuclear structure (shell effects, deformations, …) and therefore allows to probe the nuclear force far from stability. The SPIRAL1 upgrade offers the possibility to access masses of exotic nuclei which are currently either unknown or measured with large uncertainties. Different physics cases will be presented. Penning traps and MR-TOFs are nowadays the instruments of choice to measure atomic masses with high precision. Performances of these two different systems will be described. The possibility of installing PILGRIM at LIRAT for the commissioning would allow to measure masses in the near future. On a longer term, such measurements are foreseen at DESIR with MLLTRAP or an MR-TOF with more possibilities thanks to the high-quality and high-purity beams delivered to DESIR.

Orateur: Mme Pauline Ascher (CENBG)

11:25 Beta-delayed two-proton emission

Beta-delayed 2p emission is an exotic decay mode close to the limits of stability.Like in other cases of 2p emission, the decay may go through intermediate levels, if energetically available, or be a direct 2p process by the simultaneous emission of two protons. In this last case, the two protons may reveal angular and energy correlations which could be compared to nuclear structure and dynamics models to study effects like pairing, barrier penetration etc. Possible experiments with SPIRAL1 beams will be presented.

Orateur: M. Bertram Blank (CEN Bordeaux-Grradignan)

11:50 Discussion - feasibility of beams

14:00 → 16:00 ACTAR TPC, nuclear structure and reactions with accelerated beams

14:00 ACTAR TPC: First experiments with SPIRAL1 beams

The active target and time projection chamber (ACTAR TPC) is a novel high-luminosity gas-filled detection system that features a highly pixelated pad plane of more than 16K fully digitized electronic channels for studies of reactions and decays of nuclei furthest from stability. Design of the first (cubic) chamber is essentially complete and construction is ready to begin. Commissioning and the first experimental campaign with ACTAR TPC and SPIRAL1 beams are foreseen in 2017 in the G3 experimental hall. These experiments represent the first scientific deliverables of the ERC project. In this presentation, the timeline of the project and experiments being considered for the first ACTAR TPC campaign with SPIRAL1 beams will be discussed along with our requirements in terms of beam intensity, energy, and purity.

Orateur: Dr Geoffrey-Fathom Grinyer (GANIL)

14:30 Role of nuclear structure in fission around neutron-deficient Pt

The expected production of heavy ions after the Spiral1 upgrade opens a small window for the study of new fission modes recently found in 180Hg [PRL 105, 252502 (2010)]. These reveal a new role for structure effects, not observed in fission of actinides. The competition between the Coulomb barrier and the foreseen energies of the new beams would allow the study of fusion-fission around neutron-deficient Pt, just two protons away from Hg. From an experimental point of view, observables such as the neutron-proton partition of the fission fragments are a useful tool to tag the presence and influence of structure effects. These observables can be obtained with the use of the spectrometer VAMOS, providing a complete characterisation of the fission fragments and the scission point.

Orateur: Dr Manuel Caamaño (Universidade de Santiago de Compostela)

14:50 Near and sub-barrier fusion of neutron-rich light nuclei

Orateur: Dr Abdou Chbihi (GANIL)

15:10 Spectroscopy of light nuclei at the drip lines

Orateur: Dr Manuel Caamaño (Universidade de Santiago de Compostela)

15:40 Feasibility of SPIRAL beams

16:00 → 16:30 Coffee Break

16:30 → 18:30 AGATA with SPIRAL beams

16:30 Detailed spectroscopy 112Cd and 240Pu isotopes using fusionevaporation reactions with 6He beam from SPIRAL1

Orateur: Amel KORICHI (CSNSM-IN2P3/CNRS)

16:50 Direct isospin mixing measurement in Coulomb excitation of an 38mK isomeric beam

Orateur: Dr Gilles de FRANCE (GANIL/IN2P3/CNRS)

17:10 Population of the N=Z region around the 100Sn via cluster emission.

Orateur: Dr Eric Bonnet (CNRS-In2p3)

17:30 Probing the H–buring rate through the CNO–cycle via the Coulomb–excitation of 15O

Orateur: Mme Caterina Michelagnoli (GANIL)

17:50 Study of explosive hydrogen burning in classical novae using 30P and 25Al radioactive ion beams

Classical novae outbursts are very special events since they are the 3rd most energetically ones after gamma-ray bursts and supernovae. The nucleosynthesis network involved in such events is now mainly known experimentally with a few exceptions such as the $^{25}$Al(p,$\gamma$)$^{26}$Si and $^{30}$P(p,$\gamma$)$^{31}$S reactions. In this contribution we would like to emphasize the importance to develop $^{25}$Al and $^{30}$P radioactive ion beams with intensities of the order of 10$^{5}$ pps.

Orateur: Nicolas de Séréville (IPN Orsay)

19:30 → 21:30 Workshop dinner

Dinner down town at 'La Manufacture'

mercredi 10 février

09:00 → 11:00 AGATA with SPIRAL beams: Shared session with the AGATA workshop

09:00 Study of light nuclei with A=25 via multi-nucleon transfer reactions induced by radioactive beams

Orateur: Dr giovanna benzoni (INFN)

09:20 Lifetime measurements in the A~70 region using the relativistic Coulomb excitation and three-foil plunger techniques

Orateur: Dr D. M. Cullen

09:40 Mirror symmetry in the sd shell close to the proton drip line

Orateur: Andreas Vogt (Institute for Nuclear Physics, University of Cologne)

10:00 29Mg: Tracking shell evolution toward the island of inversion

Orateur: Dr Adrien Matta (University Of Surrey)

10:20 Study of n-p pairing in fp-shell through two-nucleon transfer reactions

Orateur: Dr Marlène Assié (IPNO)

11:30 → 13:00 AGATA with SPIRAL beams: Shared session with the AGATA workshop

11:30 Mapping of neutron orbitals around N=28 using 56Ni(d,p)57Ni

Orateur: Freddy FLAVIGNY (IPN Orsay)

11:50 Oblate driving force in n-deficient nuclei above 56Ni: occupation in 68Se

Orateur: M. Daniele Mengoni (University and INFN - Padova)

12:10 Structure of low-lying states in 43,45Ar studied using Coulomb excitation of SPIRAL beams

Orateur: Magda Zielinska (CEA Saclay)

12:30 Shape transition along and across N=28: 0+ 2 in 46,48Ar

Orateur: M. Daniele Mengoni (University and INFN - Padova)

12:50 Concluding remarks SPIRAL1 beams