International Journal of Modern Physics E

One major focus of the physics studied at the COoler SYnchrotron COSY of the Forschungszentrum Jülich is the production of mesons and hyperons in the hadron-hadron scattering with the aim to investigate relevant production processes, interactions of the participating particles as well as symmetries and symmetry breaking. Due to the excellent experimental conditions at COSY also single- and double-polarization measurements can be performed with high reaction rates. This contribution gives an overview about the physics program which is currently under investigation at the three big COSY installations ANKE, COSY-TOF and WASA-at-COSY.

The linearly polarized photon beam at SPring-8 is produced by backward-Compton scattering of laser photons from 8 GeV electrons. The current LEPS facility studies photo-production of hadrons in the forward angles, where the high linear polarization plays an essential role to decompose various reaction processes. In this talk, we report on the recent results from LEPS including the latest status of the Θ⁺ study.

An experiment using the novel technique of scattering a longitudinally polarized electron beam from polarized internal hydrogen/deuterium gas targets was carried out in the South Hall Ring at the MIT-Bates Accelerator Center. The scattered particles were detected by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The proton electric to magnetic form factor ratio, at Q² = 0.1 - 0.65 (GeV/c)² has been determined from the experiment by measuring the spin-dependent ep elastic scattering asymmetry in the two symmetric sectors of the BLAST simultaneously for the first time. The neutron electric form factor in the same Q² range has been extracted by measuring the spin-dependent asymmetry from the process with a vector polarized deuterium target. These results on the nucleon form factors from the BLAST experiment are presented.

We reported the observation of Y(2175) in ɸf₀(980) mass spectrum in J/ψ → ηɸf₀(980) with f₀(980) → π⁺π^-, the partial wave analysis results of J/ψ → γɸɸ, the measurement of , , and the observation of threshold enhancement in , based on 5.8 × 10⁷ J/ψ events collected at BESII. We reported the measurement of ψ(2S) radiative decays with 1.4 × 10⁷ ψ(2S) events and the measurement of D decay branching fractions with 33 pb^-1 data collected at and around 3.773 GeV as well. The status of BESIII/BEPCII project is also presented.

We report in the following, latest results from the KLOE detector at DAΦNE, the Frascati ɸ-factory. KLOE has collected 2.5 fb^-1 of e⁺e^- collisions at center of mass energy around the ɸ mass. We are completing the analyses of the 2001–2002 data sample of 450 pb^-1 and we present selected results based on the complete data sample. KLOE results could be divided into two categories kaonic and hadronic physics. We present last results on both topics describing the impact of the KLOE physics.

Excited neutral hyperons Y⁰* produced in the pp → pK⁺Y⁰* reaction with a COSY beam momentum of 3.65 MeV/c have masses below 1540 MeV/c². The ANKE spectrometer allows the simultaneous observation of different decay modes: Y⁰* → π⁰Σ⁰, π^∓Σ^±, π⁰Λ, K^-p by measuring kaons and pions of either charge in coincidence with protons.

We have found indications for a neutral excited hyperon resonance Y⁰* with a mass of M(Y⁰*) = (1480 ± 15) MeV/c² and a width of Γ(Y⁰*) = (60±15) MeV/c². The cross section for Y⁰* is of the order of few hundred nanobarns. It can be either a Σ⁰ or a Λ hyperon and on the basis of existing data no conclusion could be made whether it is a three–quark baryon or an exotic state.

Missing- and invariant–mass techniques have been used to identify the Λ(1405) resonance decaying via Σ⁰π⁰. The cross section for Λ(1405) production is equal to (4.5 ± 0.9_stat ± 1.8_syst) µb. The shape and position of the Λ(1405) distribution are similar to those found from other decay modes, so no support is given to the two-pole model.

The ANKE spectrometer at COSY-Juelich provides the possibility to select proton pairs with small excitation energy in the final state. This opens a new way to study hadron interactions at intermediate energies. The final proton pairs with small excitation energy are found presumably in the ¹S₀ state which simplifies significantly the theoretical analysis. This approach has been successfully applied to the reactions pd → {pp}_sn at high and low momentum transfer kinematics, as well as to the pp → {pp}_sπ⁰ and pp → {pp}_sγ processes.

The tensor polarization of ω mesons produced in the pd → ³Heω reaction has been measured at two energies near threshold. The ³He nuclei were detected in coincidence with the π⁰π⁺π^- or π⁰γ decay products of the ω. The ω mesons are found to be unpolarised, which is in complete contrast to the case of ϕ-meson production from the corresponding reaction pd → ³Heϕ. This brings into question the applicability of the Okubo-Zweig-Iizuka rule when comparing the production of vector mesons in low energy hadronic reactions.

Recent progress in the field of meson production in hadron collisions is presented. Special emphasis is put new developments in the application of effective field theory methods to pion production, but also theoretical concepts for two–pion, η, and vector–meson production will be presented.

The general features of strangeness production in pion-proton and proton-proton collisions are discussed. Systematic analysis of the p+p data allows to conclude that the dynamics of strangeness production at high energies is dominated by the pion exchange mechanism. That actually explains similarities between pion and proton induced reactions. Among many others features the excitation of baryon resonances coupled to strangeness is most prominent observation. However at low energies the p+p interactions allow as well for the vector meson and strange meson exchanges. The question is whether such distinctive picture of the strangeness production in proton collisions is appropriate or not? I will propose how this point can be tested with polarization measurement, which will be done in near future.

The pp → pnπ⁺ reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various N* and ∆* resonances with mass up to about 2 GeV for the pp → pnπ⁺ reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at T_p = 2.88 GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR.

The NΔ and ΔΔ dibaryon resonances are studied by calculating the NN scattering phase shifts with explicitly coupling these dibaryon channels in a multi-channel coupling calculation with two quark models. These quark models, the chiral quark model and quark delocalization color screening model, describe the NN S-, D-wave phase shifts below the π production threshold quantitatively well. Both quark models predict that the ¹D₂ resonance discovered in NN partial wave phase shift analysis and the J = 1 or 3 isoscalar resonance recently reported by CELSIUS-WASA Collaboration are NΔ⁵S₂ and ΔΔ⁷S₃ resonance respectively. Further measurements at COSY, LEPS and Lanzhou Cooling Storage Ring (CSR) to check the ΔΔ resonance are discussed.

The Λ-hypernucleus (LHN) production in the proton-induced reaction is studied in the distorted wave impulse approximation(DWIA). The cross sections for the LHN production in the reactions where the proton bombards the ⁶Li, ¹²C and ¹⁶O targets, respectively, are calculated. It is shown that the reaction cross sections are of the order of μb, and the distortion effects tend to reduce the cross sections by a factor of 3~10. For the s_Λ–LHN production, the differential cross section is decreased with the increasing mass of the target nucleus. The p_Λ–LHN production cross section is normally higher than that for the s_Λ–LHN production. The double differential cross sections (DDXS) with respect to the momenta of the outgoing proton and kaon are also demonstrated. The missing mass spectra of the inclusive reaction p+A → p+K⁺+X for the ⁶Li, ¹²C and ¹⁶O targets, an alternative way to study hypernuclear physics, are proposed. From these spectra, the masses of LHN can accurately be extracted. Moreover, the exotic LHN production in the same type of reaction is also studied . The same physical quantities are calculated. It is shown that the magnitude of the cross section is also in the order of μb. The halo effect of the core nucleus that locates at a place far away from the stable line would make the wave function broader, and consequently reduces the production cross section.

We propose to search for a tetraquark candidate in or ΛΛKK*. The existence of tetraquark state was predicted in the literature due to specific diquark effective degrees of freedom inside hadrons. In order to understand the underlying dynamics for exotic hadrons, a search for the tetraquark is strongly recommended. We make an estimate of the production rate of in an effective lagrangian theory. The proposed reaction involves two Λ production, of which the narrow widths make it a great advantage in the analysis of the final state missing mass spectrum.

We propose and study a tetra-quark state with a cyclobutadiene-like color structure, based on a color string model. Calculation with quadratic confinement and multi-string junctions shows that such a state has a ground state energy similar to that of other hidden color, tetra-quark states proposed so far. By including one-gluon exchange and one-Goldstone exchange potentials, and under the constraint of giving a good description of the meson spectroscopy, the calculation shows that Y(2175) may be a tetraquark state . The theoretical mass is about 2178 MeV, which is very close to the experimental value. The present work emphasizes that the multi-body interactions are important for multiquark systems.

Mass and lifetime measurements of stored exotic nuclei is one of the successful experimental programs at the FRS-ESR facility of GSI, Darmstadt. Two experimental techniques, namely Isochronous and time-resolved Schottky mass spectrometry have been developed. Nuclides in a very broad range of half-lives starting from stable down to only a few ten microseconds can be addressed. Single stored ions can be measured which makes these techniques highly efficient. More than 1100 atomic masses have been measured meanwhile. Half-life measurements are performed with bare and few-electron ions. Decay properties of such highly-charged ions can be dramatically different from the ones known in neutral atoms. Single-particle decay spectroscopy has been developed for investigations of two-body beta decays. A brief description of the experimental methods and recent results will be presented. Future experiments at the present facility and the perspectives with the new NuSTAR/ILIMA project at FAIR will be outlined.

The research activities at HIRFL-CSR cover the fields of the radio-biology, material science, atomic physics, and nuclear physics. This talk will mainly concentrate on the program on nuclear physics with the existing and planned experimental setups at HIRFL-CSR.

Precise mass measurements of short-lived exotic nuclei are very important for the understanding of basic nuclear structure physics and astrophysical nucleosynthesis in nature, as well as for the test and the development of theoretical nuclear mass models. At GSI, the Isochronous Mass Spectrometry (IMS) dedicated to mass measurements of short-lived nuclides was developed. In this contribution, the IMS technique is briefly reviewed. Recently, the first large-scale measurement on the ²³⁸U fission fragment was done successfully. The measured mass values are in excellent agreement with the recent Penning trap data, however, they show a systematical deviation from the values in the latest atomic mass evaluation. Some representative results from this experiment will be presented, including their impact on nuclear structure physics and astrophysical r-process nucleosynthesis.

With the commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), a pilot experiment operating the CSRe in isochronous mode to test the power of HIRFL-CSR for measuring the mass of the short-lived nucleus was performed in December of 2007. The transition point γ_t of CSRe in isochronous mode is 1.395 which corresponds to the energy about 368 MeV/u for the ions with atomic number-to-charge ratio A/q = 2. The fragments with A/q = 2 of ³⁶Ar were injected into CSRe and their revolution frequencies were measured with a fast time pick-up detector with a thin foil in the circulating path of the ions. A mass resolution of better than 10⁵ for m/Δm was achieved.

At the Gesellschaft für Schwerionenforschung mbH (GSI), atomic physics research focusses on spectroscopy of simple atomic systems at high-Z, where both the structure as well as the dynamics are determined by extreme electromagnetic fields. The Experimental Storage Ring (ESR) enables us to store these ions for long periods of time, under ideal circumstances, and to perform high-precision experiments. By means of advanced laser, target, and detector technology, we are able to address the still largely unexplored physics of these simple but exotic systems. In this paper we present some important aspects of the current and future atomic physics program, and show recent results from the ESR.

The ELISe experiment addresses the physics, scattering electrons off radioactive ions in colliding kinematics for the first time. It is an integral part of the FAIR facility as specified in the Baseline Technical Report.¹ The physics addressed covers elastic and inelastic scattering experiments for the study of charge distributions, the electromagnetic response and the single particle structure via quasielastic scattering. Details on the programme can be found in our recent publication.² The colliding beam kinematics allows for a complete reconstruction of the excitation and deexcitation process, measured via the electron and decay products with a close to 4π solid angle coverage. This complements and enhances the opportunities of the only other expected electron scattering experiment world-wide called SCRIT³ that aims for elastic scattering studies, and is especially suited for ISOL type facilities. The high centre-of-mass energy for the colliding beams, the fully identified target like ion beam, and the high reachable luminosities up to a few times 10²⁹ cm^-2s^-1 will allow to extend the projected studies exploring also the inelastic channels. In this paper, the technical design of ELISe is presented.

The commissioning of the cooler storage rings (CSR) was successful, and the facility provides new possibilities for atomic physics with highly charged ions. Bare carbon, argon ions, were successfully stored in the main ring CSRm, cooled by cold electron beam, and accelerated up to 1 GeV/u. Heavier ions as Xe⁴⁴⁺ and Kr²⁸⁺ were also successfully stored in the CSRs. Both of the rings are equipped with new generation of electron coolers which can provide different electron beam density distributions. Electron-ion interactions, high precision X-ray spectroscopy, complete kinematical measurements for relativistic ion-atom collisions will be performed at CSRs. Laser cooling of heavy ions are planned as well. The physics programs and the present status will be summarized.

Interaction of intense ion radiation with matter has numerous applications in different fields of science, ranging from basic research of plasma properties to application in energy science. Energy loss processes of heavy ions in plasma and cold matter are important to understand the generation of high energy density states in matter. The hot dense plasma of an inertial fusion target is just one example. Of special interest are phase transitions, when irradiated matter passes through the parameter regime of warm dense matter, which is located in the phase diagram at high density but relatively low temperature. Typical parameters are in the pressure range of kbar to Mbar and temperatures ranging into the few eV regime. We present an overview on recent results and developments of beam plasma, and beam matter interaction processes studied with heavy ion beams from the GSI accelerator facilities, which consist of an rf-accelerator (UNILAC: Universal Linear Accelerator), a heavy ion synchrotron (SIS 18) and an experimental storage ring (ESR). The synchrotron SIS18 currently delivers an intense uranium beam that deposits about 1 kJ/g specific energy in solid matter. Using this beam, high energy density states close to the critical point of lead, have been reached and solid lead foils have been heated to a measured brightness temperature on the order of 5000 K.

Ion traps are well suited for precision measurements also with exotic and rare species as radioactive nuclei. They provide a well controlled storage volume, stable fields and the means to handle the ion sample. The applications are first of all precise mass measurements and the therewith connected physics questions. Furthermore, ion traps are used to manipulate slow ion beams, to purify samples for decay spectroscopy or to observe the decay itself to measure for instance the β - ν correlation. An overview of the existing ion trap facilities for radioactive nuclei is given.

The status of the HIRFL (Heavy Ion Facility in Lanzhou) – Cooler Storage Ring (CSR) at the IMP is reported. The main physics goals at the HIRFL-CSR are the researches on nuclear structure and decay property, EOS of nuclear matter, hadron physics, highly charged atomic physics, high energy density physics, nuclear astrophysics, and applications for cancer therapy, space industries, materials and biology sciences. The HIRFL-CSR is the first ion cooler-storage-ring system in China, which consists of a main ring (CSRm), an experimental ring (CSRe) and a radioactive beam line (RIBLL2). The two existing cyclotrons SFC (K = 70) and SSC (K = 450) are used as its injectors. The 7 MeV/u ¹²C⁶⁺ ions were stored successfully in CSRm with the stripping injection in January 2006. After that, realized were the accelerations of ¹²C⁶⁺, ³⁶Ar¹⁸⁺, ⁷⁸Kr²⁸⁺ and ¹²⁹Xe²⁷⁺ ions with energies of 1 GeV/u, 1 GeV/u, 450 MeV/u and 235 MeV/u, respectively, including accumulation, electron cooling and acceleration. In 2008, the first two isochronous mass measurement experiments with the primary beams of ³⁶Ar¹⁸⁺ and ⁷⁸Kr²⁸⁺ were performed at CSRe with the Δp/p ~ 10^-5.

Three storage rings with a maximum magnetic rigidity of 13 Tm are foreseen as part of the FAIR project. They will mainly serve the preparation of intense secondary beams of antiprotons and rare isotopes, which are produced with high intensity proton and heavy ion beams, respectively. Cooling, by stochastic and electron cooling, and accumulation as well as deceleration of the secondary beams are manipulation techniques which are foreseen. Internal targets and collisions of rare isotope beams with electrons or antiprotons in a collider set-up will be employed in physics experiments studying the properties of the secondary beams. This report summarizes the latest design work for the FAIR storage rings.

The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton storage ring in the momentum range from 1.5 to 15 GeV/c.^1,2 The HESR is being designed and built by a consortium consisting of IKP at Forschungszentrum Jülich, TSL at Uppsala University, and GSI Darmstadt. An important feature of this new facility is the combination of phase-space cooled beams and thick internal targets (e.g. pellet targets) which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities of up to 2 · 10³²cm^-2s^-1 and high resolution mode with a relative momentum spread in the order of a few times 10^-5. To reach these beam parameters one needs a very powerful phase-space cooling utilizing high-energy electron cooling and high-bandwidth stochastic cooling. In this paper different beam dynamics issues like closed orbit correction, performance of cooled beams interacting with internal targets and luminosity considerations are discussed.

The DAΦNE e⁺e^- collider in Frascati has steadily improved its performances since year 2000, reaching in 2006 a maximum luminosity of 1.6 10³² cm^-2s^-1. Recently the crab waist collision scheme has been proposed, which allows to keep in collision two beams at large Piwinski angle with the effect of reducing the spot size at the interaction point while suppressing synchrobetatron resonances. The DAΦNE e⁺e^- collider has been upgraded according to this scheme and the first measurements are confirming the expectations. Meanwhile a proposal for an extension of the KLOE physics program, namely a KLOE-2 program, aiming to collect at least a factor of 10 more statistics with a partially upgraded detector, has been submitted. A first step of this program has been approved to take data during year 2009.

The project of The Nuclotron-based Ion Collider fAcility (NICA) that is under development at JINR is presented. The general goal of the project is to start in the coming 5–7 years experimental study of hot and dense strongly interacting barionic matter and search for possible signs of the mixed phase and critical endpoint in heavy ion collisions. The MultiPurpose Detector (MPD) is proposed for this purpose. Another goal of the NICA construction is performance of experimental studies on spin physics with colliding beams of polarized protons and light nuclei. The superconducting (SC) proton synchrotron Nuclotron, that has been constructed and being operated at JINR, is one of key elements of NICA.

The report contains description of the physics motivation (the scientific case) and main characteristics of the project: the facility scheme and operation scenario, the elements parameters, the proposed methods of intense ion beam formation, acceleration and achievement of the required luminosity of the collider. Essential feature of the project is an application of cooling methods — electron cooler in the Booster synchrotron and electron and/or stochastic cooling in the collider rings. Status and plans of the project development are presented as well.

A highly-polarized photon beam produced via the backward-Compton scattering of polarized laser photons off 8 GeV electrons is utilized for nuclear and particle physics experiments at SPring-8. The present status of the experimental facility at the Laser Electron Photon beamline (LEPS) is reported and the project at the new beam line is also discussed.

We are going to construct a precise mass-measurement apparatus; "Rare-RI Ring" at RIKEN RI Beam Factory and measure masses of exotic neutron-rich nuclei far from the stability line with the assistance of high intensity primary beam from the cyclotrons at RIBF. The present status of our project and the progress of some parts of Rare-RI Ring will be presented.

Two experimental techniques that have been developed at the COoler SYnchrotron COSY-Jülich are presented:

(i) The energy of a stored polarized proton or deuteron beam can be precisely determined by sweeping an rf magnetic dipole or solenoid field over a spin resonance. This perturbation induces a beam depolarization, which is maximal at the spin resonance's frequency. That frequency, together with the beam revolution frequency, determines the beam's kinematic γ factor, which can thus be measured with high accuracy. Therefore, the beam energy can be determined about one order of magnitude more precisely than with conventional methods based on orbit length measurements. The technique has been used at COSY for an experiment aiming at a high-precision measurement the mass of the η meson.

(ii) The repeated passage of a coasting ion beam through a thin internal target leads to a beam-energy loss and a shift of its revolution frequency. This shift is proportional to the beam-target overlap and thus allows one to measure the target thickness and hence the luminosity during the corresponding experiment. This effect has been studied quantitatively with a 2.65 GeV proton beam impinging on a hydrogen cluster-jet target at the ANKE spectrometer. After a careful error evaluation the luminosity, could be determined with an accuracy of better than 5%.

This article gives an overview of storage rings from proton to uranium. Only medium energy rings with Lorentz factors γ < 10 are treated.

After a concise historical overview the main tasks of these rings will be discussed: storage of polarized beams, beam cooling, accumulation and deceleration.

In the framework of the FAIR project the PAX Collaboration has suggested new experiments using polarized protons and antiprotons. In order to provide polarized antiprotons, the proposed mechanisms for the production of a polarized stored have to be investigated. To this aim a series of experiments have already been started with protons at the COSY ring. Additional experiment have to be foreseen at AD ring with antiprotons to define to working parameters of a dedicated Antiproton Polarizer Ring.

Proton beams were stored in COSY at 45 MeV and electron-cooled. Their lifetime was measured with gas target on and off and found to be 321.3 ± 0.4 s and 4639 ± 70 s, respectively. A model based on calculated machine parameters and the measured, interpolated residual gas distribution in COSY predicts lifetimes which are about 7 times longer. Possible reasons for this discrepancy are discussed.

The cyclotron-like storage ring dedicated to Rare-RI Ring project consists of 6 magnetic sectors and 6 straight sections, having a circumference of 56.13 m. The magnetic sector works for both bending and focusing. The total circulation is assumed to be 1,000 turns. Over the momentum range from -1% to +1% in ∆p/p, the required isochronisity is 10^-6 while the beam emittance is sevaral tens of π mm-mrad. To examine the design of cyclotron-like storage ring and fix its parameters, we have developed a high precision beam optics simulation. To achieve the precision as high as possible within a feasible computational time, we have adopted a geometrical tracking assuming a circular orbit for a small spatial segment. For that purpose, it is enough that the magnetic sector is divided into 150 sub-sectors in calculation. In each sub-sector, the magnetic field is given as a function of radial position but uniform around the vicinity of beam trajectory. The beam trajectory is evaluated in 4th order Runge-Kutta algorithm. Finally, we have achieved a precision of 10^-9 in ∆T/T and a computational time of 1.8 sec on a typical PC server for ray tracing of single particle undergoing a circulation of 1,000 turns.

Targets of frozen droplets ("pellets") from various liquefiable gases like H₂, D₂, N₂, Ne, Ar, Kr and Xe are very promising for high luminosity experiments with a 4π detector geometry at storage-rings. High effective target densities (> 10¹⁵atoms/cm²), a small target size (⊘ ≈ 20–30 μm), a low gas load and a narrow pellet beam are the main advantages of such targets.

Pioneering work on pellet targets has been made at Uppsala, Sweden.¹ A next generation target has been built at the IKP of FZJ in collaboration with two institutes (ITEP and MPEI) from Moscow, Russia. It is a prototype for the future pellet target at the PANDA experiment at FAIR/HESR (supported by INTAS 06-1000012-8787, 2007/08) and makes use of a new cooling and liquefaction method, based on cryogenic liquids instead of cooling machines.² The main advantages of this method are the vibration-free cooling and the possibility for cryogenic jet production from various gases in a wide range of temperatures. Different regimes of pellet production from H₂, N₂ and Ar have been observed and their parameters have been measured.³ For the first time, mono-disperse and satellite-free droplet production was achieved for cryogenic liquids from H₂, N₂ and Ar.

A first storage cell for the Polarized Internal gas Target (PIT) of the ANKE facility at COSY was produced from a Teflon-coated pure Aluminum foil and successfully used in the double polarized experiment with a 1.2 GeV polarized deuteron beam carried out at the COSY accelerator in January 2007. Prior to this experiment, the minimum possible cross section of the storage-cell beam tube at the interaction point at ANKE was determined, based on the COSY beam profile at different beam formation stages. Electron cooling combined with stacking and stochastic cooling have been studied as well. Experiments with N₂ gas in the storage cell to simulate the background produced by beam interaction with the aluminum cell walls were performed. The analysis of the and reactions showed that events from the extended target can be clearly identified in the ANKE detector system. Taking into account the known intensity of the Atomic Beam Source (ABS), the expected target density in the experiment with a storage-cell beam tube of 15_hor × 20_vert × 390_long mm³ and a 130 mm long feeding tube with 15 mm diameter reach values of 3.2 × 10¹³ at/cm². The polarization, measured by the np → dπ⁰ reaction with the storage-cell, was 0.75 ± 0.06.

We have established a novel method which make electron scattering off short-lived radioactive nuclei come into being. This novel method was named SCRIT (Self-Confining RI ion Target). It was based on the well known "ion trapping" phenomenon in electron storage rings. Stable nucleus, ¹³³Cs, was used as target nucleus in the R&D experiment. The luminosity of interaction between stored electrons and Cs ions was about 1.02(0.06) × 10²⁶cm^-2s^-1 at beam current around 80 mA. The angular distribution of elastically scattered electrons from trapped Cs ions was measured. And an online luminosity monitor was used to monitor the change of luminosity during the experiment.

This contribution presents some results from the first feasibility measurement performed at GSI using a 350 MeV/nucleon ¹³⁶Xe beam and a Hydrogen gas-jet target. In this feasibility study, one element of every possible detection part of the future EXL detection system was investigated. In addition, simulation results for EXL setup will be presented.