Present and future experiments with stored exotic nuclei at relativistic energies

Pioneering experiments with stored and cooled exotic nuclei at relativistic energies have been performed using the combination of the fragment separator FRS with the storage-cooler ring ESR. Exotic nuclei created in peripheral collisions are spatially separated in-flight and injected into the storage ring for high-precision mass and unique lifetime measurements. Lifetimes of stored bare and few-electron nuclei have been measured to study the influence of the electron density on the β decay. This condition, relevant for stellar plasma, can now be systematically investigated in the laboratory for the first time. Characteristic experiments of the present FRS-ESR system are presented and perspectives for a next-generation facility are briefly outlined. Received: 1 May 2001 / Accepted: 4 December 2001     

Present and future experiments with stored exotic nuclei at the FRS-ESR facility

High accuracy mass and lifetime measurements are performed with the combination of the in-flight separator FRS and the cooler-storage ring ESR at GSI. Exotic nuclei are produced via projectile fragmentation and fission at (400–900) MeV/u. This energy range is the basis for unique experimental conditions with bare and few-electron fragments and allows for the first time investigations for decay channels which are rare or strictly forbidden in neutral atoms. New experimental developments and data including the discovery of new isotopes are presented. The comparison of the experimental results with theoretical predictions indicates the potential for improvements of nuclear models. A new generation of experiments will be possible with the advent of the proposed international Facility for Antiproton and Ion Research (FAIR).     

Radioactive beams at TRIUMF: Present and future studies

In 1985, a high intensity, accelerated radioactive beam facility (ISAC) of the ISOL type, devoted mainly to studies in nuclear astrophysics, was proposed for installation. A report on the present status of radioactive beam research using the successfully operating TISOL is given, together with a summary of the future plans of these programs including an upgrade of TISOL to accommodate >10 A and a revised ISAC proposal.     

Nucleon transfer reactions with exotic beams at ATLAS

We present some recent results from studies of light nuclei using exotic beams from ATLAS at Argonne National Laboratory. Light nuclei far from stability provide ideal testing grounds for modern theoretical methods, and may provide information about astrophysical environments. We focus on the nuclei ⁹Li and ⁷He, populated with the (d,p) and (d,³He) reactions.     

Spectroscopy of nuclei far from stability at GANIL: Recent experiments

The structure of neutron-rich light nuclei around N = 20, 28 has been investigated at GANIL by means of in-beam gamma spectroscopy using fragmentation reactions of ³⁶S and ⁴⁸Ca beams on a Be target. Gamma decay of relatively high-lying excited states have been measured for the first time in nuclei around ³²Mg and ⁴⁴S. Level schemes are proposed and discussed for a large number of these neutron-rich nuclei around N = 20 and N = 28. Received: 1 May 2001 / Accepted: 4 December 2001     

In-beam gamma-ray spectroscopy with exotic beams at the NSCL

Projectile fragmentation provides radioactive beams at intermediate velocities (v/c = 0.3-0.5) by physical means of fragment separation. With the development of position-sensitive photon detectors it has become possible to measure the energies and directions of photons emitted in-flight from such fast-moving exotic beams. This allows the reconstruction of the photons' energies emitted from an exotic projectile with high accuracy. It can be advantageous to employ photon detection in experiments with exotic beams since photons can traverse matter easily and their attenuation can be calculated. Experiments with standard luminosities can be carried out at intermediate beam energies with thick secondary targets (order of g/cm²) and very low incident beam rates (order of particle/s or less). Experimental success in this field is strongly correlated with the development of photon detectors such as position-sensitive scintillation detectors or segmented germanium detectors. In-beam gamma-ray spectroscopy of fast exotic beams has been successfully used at all projectile fragmentation facilities in intermediate-energy heavy-ion inelastic scattering experiments, knockout reactions and fragmentation reactions. Here, we focus on experimental results for neutron-rich exotic nuclei in the π(sd )-shell. Measurements and detector developments carried out at the NSCL at Michigan State University during the last four years are discussed. Received: 1 May 2001 / Accepted: 4 December 2001     

Precision measurements with LPCTrap at GANIL

The experimental achievements and the results obtained so far with the LPCTrap device installed at GANIL are presented. The apparatus is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β ? ν angular correlation parameter in nuclear β decays. So far, the data collected with three isotopes have enabled to determine, for the first time, the charge state distributions of the recoiling ions, induced by shakeoff process. The analysis is presently refined to deduce the correlation parameters, with the potential of improving both the constraint deduced at low energy on exotic tensor currents (⁶He¹⁺) and the precision on the V _{u d} element of the quark-mixing matrix (³⁵Ar¹⁺ and ¹⁹Ne¹⁺) deduced from the mirror transitions dataset.     

Radioactive nuclear beams: Present and future

Some results of investigations into a new nuclear-physics field associated with the production of radioactive nuclear beams and physical studies with these beams are presented. The most recent results obtained by studying the structure of nuclei and reaction mechanisms with radioactive nuclear beams are surveyed. Data obtained in Dubna at the DRIBs accelerator complex are presented along with allied results from other research centers. In this connection, existing experimental data on light loosely bound exotic nuclei are discussed. The parameters of DRIBs3, which is a new accelerator complex, are presented, and the physics research program that will be implemented with the aid of new setups, including a high-resolution magnetic analyzer (MAVR) and a 4π neutron detector (TETRA), is described. A collaboration in the realms of employing radioactive nuclear beams at the DRIBs complex together with other accelerator complexes [SPIRAL2 (France), RIKEN (Japan), FAIR (Germany), and RIBF (CIIIA)] on the basis of employing new highly efficient experimental facilities has already led to the discovery of new phenomena in nuclear physics and will make it possible to study in the future new regions of nuclear matter in extreme states.     

Present and future of neutrino oscillation experiments

Results of a new study of the discovery potential within mSUGRA parameter space of inclusive searches for SUSY at ATLAS are presented. These results indicate that superior performance is provided by the jets + E_T^miss channel in which no requirements are placed upon lepton multiplicity. The sensitivity of this and other channels is mapped in m₀ - m_1/2 parameter space for four different values of tan(β) with similar performance being obtained in all cases. Inclusive measurements of the effective mass scale M_susy^eff and total production cross-section σ_susy of supersymmetric particles are also discussed and results presented of a study of the likely measurement precisions.     

Experiments with exotic atoms and exotic nuclei at GSI, recent developments and future prospects

Results and new developments with exotic atoms and exotic nuclei are presented from recent experiments at GSI. The proposed European inflight facility at GSI will open up new fields of outstanding research and will simultaneously access unknown regions of nuclei with new properties. A new generation of precision experiments will be performed with stored exotic nuclei, whereby nuclear reactions with an internal target and electron scattering in a small electron-ion collider will be a great challenge.     

Recent experiments with radioactive ion beams at GSI

A review is given over recent experiments performed by means of A·keV to A·GeV radioactive ion beams at GSI Darmstadt. Nuclear structure information on exotic nuclei is discussed as obtained by using an online isotope separator, a velocity filter or a magnetic beam-line spectrometer.     

First beams and experiments at the nuclotron

The new heavy ion superconducting synchrotron - Nuclotron was put into operation and the pilot physics results on relativistic nuclear collisions were obtained.     

Present and future experiments in nonequilibrium reactor antineutrino energy spectrum

Considerable efforts that have been undertaken in recent years in low-energy antineutrino experiments require further systematic investigations in line of reactor antineutrino spectroscopy as a metrological basis of these experiments. We consider some effects associated with the nonequilibrium of reactor radiation and residual emission from spent reactor fuel in contemporary experiments. The text was submitted by the authors in English.     

Double-beta-decay experiments: Present status and prospects for the future

The present status of experiments seeking double-beta decay is surveyed. The results of the most sensitive experiments are discussed. Particular attention is given to describing the NEMO-3 detector, which is intended for seeking the neutrinoless double-beta decay of various isotopes (¹⁰⁰Mo, ⁸²Se, etc.) with a sensitivity as high as T _1/2 ～ 10²⁵ yr, which corresponds to a sensitivity to the Majorana neutrino mass at a level of 0.1 to 0.3 eV. The first results obtained with the NEMO-3 detector are presented. A review of the existing projects of double-beta-decay experiments where it is planned to reach a sensitivity to the Majorana neutrino mass at a level of 0.01 to 0.1 eV is given.     

Fission experiments with secondary beams

Nuclear fission from excitation energies around 11 MeV was studied at GSI, Darmstadt for 76 neutron-deficient actinides and pre-actinides by use of relativistic secondary beams. The characteristics of multimodal fission of nuclei around ²²⁶Th are systematically investigated and related to the influence of shell effects on the potential-energy and on the level density between saddle point and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in fission.     

Potential and limitations of nucleon transfer experiments with radioactive beams at REX-ISOLDE

As a tool for studying the structure of nuclei far off stability the technique of γ-ray spectroscopy after low-energy single-nucleon transfer reactions with radioactive nuclear beams in inverse kinematics was investigated. Modules of the MINIBALL germanium array and a thin position-sensitive parallel plate avalanche counter (PPAC) to be employed in future experiments at REX-ISOLDE were used in a test experiment performed with a stable ³⁶S beam on deuteron and ⁹Be targets. It is demonstrated that the Doppler broadening of γ lines detected by the MINIBALL modules is considerably reduced by exploiting their segmentation, and that for beam intensities up to 10⁶ particles/s the PPAC positioned around zero degrees with respect to the beam axis allows not only to significantly reduce the γ background by requiring coincidences with the transfer products but also to control the beam and its intensity by single particle counting. The predicted large neutron pickup cross-sections of neutron-rich light nuclei on ²H and ⁹Be targets at REX-ISOLDE energies of 2.2 MeV ^. A are confirmed. Received: 9 October 2000 / Accepted: 28 January 2001