Three-body correlations in direct reactions: Example of 6^{6}Be populated in (p,n)(p,n) reaction

The $^{6}$Be continuum states were populated in the charge-exchange reaction $^1$H($^{6}$Li,$^{6}$Be)$n$ collecting very high statistics data ($\sim 5 \times 10^6$ events) on the three-body $\alpha$+$p$+$p$ correlations. The $^{6}$Be excitation energy region below $\sim 3$ MeV is considered, where the data are dominated by contributions from the $0^+$ and $2^+$ states. It is demonstrated how the high-statistics few-body correlation data can be used to extract detailed information on the reaction mechanism. Such a derivation is based on the fact that highly spin-aligned states are typically populated in the direct reactions.Comment: submitted to Physical Review

Status of the ACCULINNA-2 project at FLNR

The project of a new and more powerful in-flight fragment separator ACCULINNA-2 at U-400M cyclotron in FLNR, JINR planned to build in addition to the existing separator ACCULINNA is presented. The new separator will provide high intensity RIBs in the lowest energy range (5÷50 MeV/nucleon) which is attainable for in-flight separators. The possibilities for the astrophysics studies at the proposed device are presented. ACCULINNA-2 separator is planned to be constructed in the years 2010-2015. The current status of the project is reported

EBIS debuncher experimental performance

International audienceThe recent test of a prototype of beam debuncher device for Electron Beam Ion Source (EBIS), designed within the EMILIE (Enhanced Multi-Ionization of short-Lived Ions for EURISOL) project, is presented in this paper. For a singly ionized Li+1 ion, high efficiency trapping times up to 1 s were established and a uniform ion extraction with intensity variation of less than 30% was achieved. The test gives promising results regarding the future introduction of debuncher devices to EBIS facilities

Research of CB ECRIS plasma with the aid of injected 1+ beam

International audienceAn anomalous global efficiency of the extracted 1+ beam was discovered at the LPSC charge breeder. It was realized that a fraction of injected 1+ beam propagates through the charge breeder plasma without being captured and ionized. As a result of the further experiments andtheoretical considerations it was realized and confirmed that 1+ beam injected into the chargebreeder plasma can be used as a plasma diagnostics tool. Identification of the uncaptured fractionof the 1+ ions allow, for example, estimating the ion-ion collision mean free path of injected 1+beam and plasma densities as a function of microwave power. The presentation will describein more detail the injected 1+ beam as a diagnostic tool to reveal information about differentplasma parameters. Further more, the prospects to use charge breeder ECRIS to study the effectof gas mixing on the ion confinement time will be discussed

Injected 1+ ion beam as a diagnostics tool of charge breeder ECR ion source plasmas

International audienceCharge breeder electron cyclotron resonance ion sources (CB-ECRIS) are used as 1+  →n+  charge multiplication devices of post-accelerated radioactive ion beams. The charge breeding process involves thermalization of the injected 1+  ions with the plasma ions in ion–ion collisions, subsequent ionization by electron impact and extraction of the n+  ions. Charge breeding experiments of 85Rb and 133Cs ion beams with the 14.5 GHz PHOENIX CB-ECRIS operating with oxygen gas demonstrate the plasma diagnostics capabilities of the 1+  injection method. Two populations can be distinguished in the m/q-spectrum of the extracted ion beams, the low (1+  and 2+) charge states representing the uncaptured fraction of the incident 1+  ion beam and the high charge states that have been captured in ion–ion collisions and subsequently charge bred through electron impact ionization. Identification of the uncaptured fraction of the 1+  ions allows estimating the lower limit of ion–ion collision frequency of various charge states in the ECRIS plasma. The collision frequencies of highly charged ions (~107 Hz) are shown to exceed their gyrofrequencies (~106 Hz) at least by an order of magnitude, which implies that the dynamics of high charge state ions are dictated by magnetically confined electrons and ambipolar diffusion and only low charge state ions can be considered magnetized. Furthermore, it is concluded that the plasma density of the ECRIS charge breeder is most likely on the order of 1011 cm−3 i.e. well below the critical density for 14.5 GHz microwaves

Experimental Activities with the LPSC Charge Breeder in the European Context

One of the Work Packages of the "Enhanced MultiIonization of short-Lived Isotopes at EURISOL" NuPNET project focuses on the ECR charge breeding. The LPSC charge breeder is used for experimental studies in order to better understand the fundamental processes involved in the 1+ beam capture by a 14 GHz ECR plasma. Some improvements, like symmetrisation of the magnetic field at the injection side and higher pumping speed, have been carried out on the PHOENIX charge breeder. The impact of these modifications on the efficiencies and charge breeding times are presented. In the same time, the new LPSC 1+ source developments performed in order to ease the efficiency measurements with various elements are presented.nonPeerReviewe

Ionization efficiency studies with charge breeder and conventional electron cyclotron resonance ion source

International audienc

LPSC contributions to the Emilie project

International audienceIn the frame of the Emilie project, in order to better understand the physics of the Charge Breeder process, the LPSC acted on several levers. First, the 1+N+ test bench was used to makeexperiments with 3 versions of the Phoenix Charge Breeder: LPSC, SPES and SPIRAL1. Inparallel, two 1+ electron cyclotron resonance ion sources have been developed. The first is a hot(650°C) version of the 2.45 GHz COMIC source, which aims is to produce 1+ alkali ions and tostudy the atom ionization efficiency dependence with temperature (wall recycling). The secondone is a new 5.8 GHz source able to produce stable low charge state ion beams. A roadmap forthe future developments of the Charge Breeder has been defined at LPSC. First, an upgrade ofthe magnetic field configuration is considered in order to enhance the plasma confinement. Thiswould possibly allow 18 GHz experiments. Second, the injection of several low charge state ionswill be carried out to investigate further the ion capture process in the plasma, helped with newplasma diagnostics. The results of these experiments and developments will be presented togetherwith the new development plan of the Charge Breeder

Unbound states studied by direct reactions

International audienceThe t(6He,8He)p t(8He,10He)p reactions were studied in experiments with 25A MeV 6He beam and 27.4A MeV 8He beams and an unique tritium gas target. Results on the 8He and 10He excitation energy spectra are presented. The 8He spectrum exhibits 3 states, apart of the ground state and known (2+) state at 3.6 MeV, the third state is seen at 5.4 MeV. A tentative assignment 1+ is proposed for this structure. The 10He spectrum shows no event at the excitation energy below 3 MeV what is in contradiction with the earlier reports on this nucleus. A high statistics of α-n coincidence events collected for the 8He beam run has been subjected to analysis in order search for the bound tetraneutron. The search produced a negative result

Ionization efficiency studies with charge breeder and conventional electron cyclotron resonance ion source

Radioactive Ion Beams play an increasingly important role in several European research facility programs such as SPES, SPIRAL1 Upgrade, and SPIRAL2, but even more for those such as EURISOL. Although remarkable advances of ECRIS charge breeders (CBs) have been achieved, further studies are needed to gain insight on the physics of the charge breeding process. The fundamental plasma processes of charge breeders are studied in the frame of the European collaboration project, EMILIE, for optimizing the charge breeding. Important information on the charge breeding can be obtained by conducting similar experiments using the gas mixing and 2-frequency heating techniques with a conventional JYFL 14 GHz ECRIS and the LPSC-PHOENIX charge breeder. The first experiments were carried out with noble gases and they revealed, for example, that the effects of the gas mixing and 2-frequency heating on the production of high charge states appear to be additive for the conventional ECRIS. The results also indicate that at least in the case of noble gases the differences between the conventional ECRIS and the charge breeder cause only minor impact on the production efficiency of ion beams.peerReviewe