Search

The one-neutron removal cross sections of neutron-rich Al isotopes and longitudinal momentum distributions of the residues have been measured for A = 33 to 36 at relativistic energies (≈900 MeV/u). The inclusive data have been interpreted within the eikonal approximation. The evolution of the single-particle occupancy in the ground state of 33,34,35A1 has been studied and compared with shell model predictions. The inferred 2s1/2 neutron occupancy in the 33A1 ground-state wave function is 20% to 40% lower than the predicted one. The inclusive data do not exclude the presence of intruder states. Some intruder / = 1 occupancy is found in 34A1, similarly to 33Mg. The single-particle 1 f7/2 occupancy shows a gradual increase at N = 22. Correspondingly, a decrease of the lrf3/2 strength has been observed. [ABSTRACT FROM AUTHOR]

Abstract: The first reaction spectroscopy on the ground state structure of 33Mg through the measurement of the longitudinal momentum distribution from the one-neutron removal reaction using a C target at is reported. The experiment was performed at the FRS, GSI. The distribution has a relatively narrow width ( (FWHM)) and the one-neutron removal cross-section is . An increased contribution from the orbital is required to explain the observation showing its lowering compared to existing model predictions. This provides new information regarding the configuration of 33Mg and the island of inversion. [Copyright &y& Elsevier]

Experimental signatures of the dynamical correlations of a core with a single-particle neutron have been found in light neutron-rich nuclei investigated via the ( 7Li, 7Be) charge-exchange reactions at around 8MeV/u. Of particular astrophysical relevance are low-lying narrow resonances ( Γ ∼ 200keV FWHM) BSEC (Bound States Embedded in the Continuum). Because of their long lifetime BSEC states are likely to effect the capture rates in any scenario for nucleosynthesis in neutron-rich environment. They have been observed in the continuum of 11Be and 15C nuclei. A microscopic nuclear structure model based on QRPA theory, which takes into account Dynamical Core Polarisation (DCP) correlations, gives a suitable description of these resonances as well as single-particle states of the studied systems. In this context, high-energy narrow structures populated in nuclei having an integer number of α-particles plus three neutrons are good BSEC candidates and can be systematically investigated. [ABSTRACT FROM AUTHOR]

Abstract: The ground-state structure of the near-drip-line nucleus 23O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections for electromagnetic excitation of 23O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including γ rays. The analysis of the deduced dipole-transition probability into the continuum infers a ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin , resolving earlier conflicting experimental findings. Final-state interaction is of significant influence, an effective reduced scattering length for low-energy neutron scattering could be derived from the data. [Copyright &y& Elsevier]

Objective. Beams of stable ions have been a well-established tool for radiotherapy for many decades. In the case of ion beam therapy with stable 12C ions, the positron emitters 10,11C are produced via projectile and target fragmentation, and their decays enable visualization of the beam via positron emission tomography (PET). However, the PET activity peak matches the Bragg peak only roughly and PET counting statistics is low. These issues can be mitigated by using a short-lived positron emitter as a therapeutic beam. Approach. An experiment studying the precision of the measurement of ranges of positron-emitting carbon isotopes by means of PET has been performed at the FRS fragment-separator facility of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany. The PET scanner used in the experiment is a dual-panel version of a Siemens Biograph mCT PET scanner. Main results. High-quality in-beam PET images and activity distributions have been measured from the in-flight produced positron emitting isotopes 11C and 10C implanted into homogeneous PMMA phantoms. Taking advantage of the high statistics obtained in this experiment, we investigated the time evolution of the uncertainty of the range determined by means of PET during the course of irradiation, and show that the uncertainty improves with the inverse square root of the number of PET counts. The uncertainty is thus fully determined by the PET counting statistics. During the delivery of 1.6 × 107 ions in 4 spills for a total duration of 19.2 s, the PET activity range uncertainty for 10C, 11C and 12C is 0.04 mm, 0.7 mm and 1.3 mm, respectively. The gain in precision related to the PET counting statistics is thus much larger when going from 11C to 10C than when going from 12C to 11C. The much better precision for 10C is due to its much shorter half-life, which, contrary to the case of 11C, also enables to include the in-spill data in the image formation. Significance. Our results can be used to estimate the contribution from PET counting statistics to the precision of range determination in a particular carbon therapy situation, taking into account the irradiation scenario, the required dose and the PET scanner characteristics. [ABSTRACT FROM AUTHOR]

The present work reports on a long-term irradiation test performed on a 0.3-mm thick polycrystalline diamond detector prototype. The device, biased at 300 V, was continuously irradiated for about 60 h by using a 12C beam at 62 MeV/nucl. at the LNS-INFN Cyclotron facility in Catania. An ionization chamber, calibrated using a single crystal diamond detector, was used to evaluate the total absorbed dose in the diamond detector under study. Data analysis carried out on recorded oscilloscope waveforms shows no significant variation of the signal properties in terms of amplitude, slope and charge after exposure to an integrated flux of 6.2⋅ 1013 ions/cm2. The results indicate that a polycrystalline diamond detector can be used for calibrating intensity monitors at the future superconducting fragment separator Super-FRS at FAIR (Darmstadt). • No change observed in the signal proprieties of an irradiated pcCVD diamond material • Diamond detectors as precise intensity monitors with heavy ion beams • Survival of a pcCVD diamond detector after long-term beam current calibrations [ABSTRACT FROM AUTHOR]

As an essential part of the Super-FRS particle identification, the GEM-TPC detector in a twin field-cage configuration will provide position information at up to 1 MHz counting rate with a spatial resolution < 1 mm and with tracking efficiency > 95 %. This detector is designed to provide particle-beam tracking information of projectiles ranging from protons to uranium. The performance of the GEM-TPC detector in a single field-cage configuration and newly integrated AWAGS readout electronics with a differential output was studied at the FRS for the response to the uranium beam at 850 MeV/u with intensity up to 1000 ions/spill. The result shows that a clusterization algorithm developed for this analysis works properly. The spatial resolution of 0.74–0.81 mm, a detection efficiency > 99 %, and a tracking efficiency > 96 % were found. This work describes the methodology used to achieve such results in detail. [ABSTRACT FROM AUTHOR]

The HISPEC/DESPEC collaboration envisages long experimental campaigns exploiting the expected beam performances of Super-FRS. The experiments will be performed at the Low-Energy Branch of the upcoming FAIR and will focus on the physics of exotic isotopes, primarily in the heavy neutron-rich region. The goal of the HISPEC/DESPEC experimental campaigns is to explore the excitation and decay properties of rare isotopes produced via fragmentation and fission. First rare-isotope beam simulations of representative future HISPEC/DESPEC experimental cases are presented. The simulations provide an insight into the forthcoming state-of-art experiments in the future FAIR facility. [ABSTRACT FROM AUTHOR]

Results of the HypHI Phase 0 experiment with the reaction of 6 Li+ 12 C at 2 A GeV are summarised. Invariant mass distributions as well as the lifetime measurements for 3 Λ H and 4 Λ H are discussed. The lifetime values for both the hypernuclei are respectively observed to be 183 +42 −32 ps and 140 +48 −33 ps, being significantly shorter than those of the Λ-hyperon. Statistical analyses of existing lifetime data for 3 Λ H up to 2014 confirm a significantly short lifetime of 3 Λ H, which is not explained by present models. Observed hypernuclear production cross section values for 3 Λ H and 4 Λ H are also summarised. In addition, observed signals for the final states of d + π − and t + π − are discussed. All the discussions on the results of the HypHI Phase 0 experiment in this article are based on [1–4] . We also present a new proposed experiment with the FRS (FRagment Separator) at GSI (FAIR Phase 0) to improve the precision of the hypernuclear spectroscopy with peripheral heavy ion induced reactions. [ABSTRACT FROM AUTHOR]

New tracking detectors are necessary for beam diagnostics and event-by-event particle identification for the Super-FRS, a next generation reaction product separation being constructed at GSI/FAIR in Germany. Novel detectors and electronics are currently being developed to meet the stringent requirements of this forefront fragment separator due to high radiation levels, long term electronic stability and the required homogeneity of materials in the beam, while maintaining very high tracking efficiency. The present contribution focuses on the electronics for a new Gas Electron Multiplier (GEM)-based Time Projection Chamber (TPC) to provide the position information, which are needed to reconstruct the A/q of the fragment from protons to uranium ions. The most recent Front End Electronics (FEE) developed at GSI with a novel Amplifier With Adaptive Gain Settings (AWAGS) ASIC are being tested. This FEE has a low noise level (sub fC), a large dynamic range (up to ∼ 71 pC) with excellent timing properties. The AWAGS uses a switched capacitance technique instead of fixed feedback capacitors to provide the large dynamic range. Results from the ASIC characterisation studies and the outlook for a new, updated chip for the full read out chain of the GEM TPC are presented. [ABSTRACT FROM AUTHOR]

A 410 MeV/u 238 U projectile beam was used to create cadmium isotopes via abrasion-fission in a beryllium target placed at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated by the FRS and injected into the isochronous storage ring ESR for mass measurements. Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B ρ -tagging at the high-resolution central focal plane of the FRS. In the experiment with B ρ -tagging the magnetic rigidity of the injected fragments was determined with an accuracy of 2 ⋅ 10 − 4 . A new method of data analysis, which uses a correlation matrix for the combined data set from both experiments, has provided experimental mass values of 25 rare isotopes for the first time. The high sensitivity and selectivity of the method have given access to nuclides detected with a rate of a few atoms per week. In this letter we present for the 129,130,131 Cd isotopes mass values directly measured for the first time. The experimental mass values of cadmium as well as for tellurium and tin isotopes show a pronounced shell effect towards and at N = 82 . Shell quenching cannot be deduced from a single new mass value, nor by a better agreement with a theoretical model which explicitly takes into account a quenching feature. This is in agreement with the conclusion from γ -ray spectroscopy and confirms modern shell-model calculations. [ABSTRACT FROM AUTHOR]

Abstract: We report on a new liquid hydrogen and deuterium target dedicated to in-beam γ spectroscopy experiments in inverse kinematics at relativistic incident energies at GSI/FAIR. Target thicknesses from 10 to 80mm can be achieved for an effective diameter of 60mm. The target-cell and entrance window are maded of thick Mylar. The design has the advantage of being free of absorbing material at forward angles and 90°, allowing the detection of photons in a wide angular range. A commissioning experiment with a 54Cr beam at 130MeV/nucleon has been performed at GSI, using the Rare Isotopes INvestigation at GSI (RISING) detectors. The target has been shown to behave as expected and is ready for experiments at fragmentation Radioactive-Ion Beam Facilities. [Copyright &y& Elsevier]

Isomeric ratios have been determined for 23 metastable states identified in A ≈ 200 nuclei from Pt to Rn near the valley of stability following fragmentation of 238U. This includes high-spin states with angular momenta ranging from (39/2)ħ to 25ħ. The experimental results are discussed together with those of similar experiments performed in this mass region. Isomeric ratios are compared with theoretical predictions where the angular momentum of the fragment arises purely due to the angular momentum of nucleons removed from the projectile. The theoretical yield of low-spin states is generally overestimated. In these cases the assumption of 100% feeding of the isomer may require modification. However, the yield of high-spin isomeric states [Im ≥ (39/2)ħ] is significantly underestimated and highlights the requirement for a more complete theoretical framework in relation to the generation of fragment angular momentum. The enhanced population of high-spin states reported here is advantageous to future studies involving isomeric beams at fragmentation facilities such as the Rikagaku Kenkyusho RI Beam Factory (Japan) and next-generation facilities at the Facility for Antiproton and Ion Research (Germany) and Facility for Rare Isotope Beams (USA). [ABSTRACT FROM AUTHOR]

High-precision measurement of half-life and Qa value of neutral and highly charged a emitters is a major subject of investigation currently. In this framework, we recently pushed half-life measurements of neutral emitters to a precision of a few per mil. This result was achieved by using different techniques and apparatuses at Istituto Nazionale di Fisica Nucleare Laboratori Nazionali del Sud (INFN-LNS) and GSI Darmstadt. Here we report on 213Fr half-life determination [T1/2(213Fr) =34.14 ± 0.06 s] at INFN-LNS, detailing the measurement protocol used. Direct comparison with the accepted value in the literature shows a discrepancy of more than three sigma. We propose this new value as a reference, discussing previous experiments. [ABSTRACT FROM AUTHOR]

Abstract: The Super-FRS in-flight fragment separator at FAIR will be used to produce exotic nuclei at relativistic energies. High resolution experiments in ion traps with the separated fragments will be performed after they are slowed-down in matter and quickly extracted from a gas-filled stopping cell. Such experiments require an effective range bunching with a high-resolution magnetic spectrometer in combination with a wedge-shaped degrader at the dispersive focal plane. The ion-optical system of the spectrometer proposed here is rather versatile because it consists of several dipole and quadrupole magnets arranged such to serve as an energy-buncher and also as a large-acceptance spectrometer for the analysis of secondary reaction products. The performance and the experimental potential of such a multi-purpose spectrometer are described. [Copyright &y& Elsevier]

Abstract: Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of . The new isotopes were unambiguously identified in reactions with a beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium. [Copyright &y& Elsevier]

Abstract: In the present work, the differential cross sections for small-angle proton elastic scattering on the 12,14Be nuclei were measured in inverse kinematics, using secondary radioactive beams with energies near 700 MeV/u produced with the fragment separator FRS at GSI. The main part of the experimental setup was the active target IKAR, which was used simultaneously as a target and a detector for the recoil protons. Auxiliary detectors for projectile tracking and isotope identification completed the setup. The measured differential cross sections were analyzed using the Glauber multiple-scattering theory. For the evaluation of the data several phenomenological nuclear-matter density parametrizations and a sum of Gaussian parametrization were used. The nuclear-matter radii and radial density distributions of the isotopes 12,14Be were deduced. Extended nuclear-matter density distributions were observed in both isotopes, and the halo structure of 14Be was confirmed. The results were also compared with microscopic few-body and fermionic molecular dynamics model calculations concerning the structure of these neutron-rich nuclei. [Copyright &y& Elsevier]

New measurements of the interaction cross sections of 22,230 at 900A MeV performed at the GSI, Darmstadt are reported that address the unsolved puzzle of the large cross section previously observed for 230. The matter radii for these oxygen isotopes extracted through a Glauber model analysis are in good agreement with the new predictions of the ab initio coupled-cluster theory reported here. They are consistent with a 220 + neutron description of 230 as well. [ABSTRACT FROM AUTHOR]

Abstract: Time Projection Chambers with C-pads and integrated delay line readout were developed as position sensitive detectors for the Fragment separator at GSI Darmstadt. The main advantages of TPCs are a small amount of matter in the sensitive volume, high spatial resolution, and high tracking efficiency. Working parameters in experimental conditions are presented. Internal spatial resolutions of and were achieved. The tracking efficiency dependence on ion beam intensity was studied with 238U beam at 1 GeV/u energy. Efficiency of more than 99% was achieved up to 40kHz and over 90% for 250kHz 238U beam intensity. Different kinds of ions from proton to uranium were measured in many experiments and confirmed the result obtained. [Copyright &y& Elsevier]

The feasibility studies of the slowed down beam setup involving deceleration of a 64Ni beam at 250 MeV/u to 13 MeV/u in a thick Al degrader was performed at the FRagment Separator (FRS) at GSI. The experimentally measured energy spread and the nuclear reaction yields in the degrader are in good agreement with simulations. [ABSTRACT FROM AUTHOR]

The interaction cross sections of 32-35Mg at 900A MeV have been measurmed using the fragment separator at GSI. The deviation from the r0A1/3 trend is slightly larger for 35Mg, signaling the possible formation of a longer tail in the neutron distribution for 35Mg. The radii extracted from a Glauber model analysis with Fermi densities are consistent with models predicting the development of neutron skins. [ABSTRACT FROM AUTHOR]

One-neutron knockout reactions have been studied in a systematic way for a set of neutron-rich projectiles. The goal of the experiment, performed at GSI, was to explore the evolution of the nuclear structure close to the neutron drip line, in the region between C and Al. The momentum distributions of the surviving fragments and the cross-sections of the knockout process have been measured and used as physical observables. This report focuses on oxygen and nitrogen isotopes around N = 14. In particular, we discuss the case of 22N, for which the mentioned observables have been determined for the first time. We will consider 23O, already studied in earlier experiments, as a reference. [ABSTRACT FROM AUTHOR]

Dipole strength distributions measured in unstable neutron-rich nuclei in the 132Sn mass region by utilizing relativistic Coulomb excitation of radioactive beams reveal a sizable fraction of "pygmy" strength below the giant dipole resonance. On the grounds of the RQRPA model, a strong linear correlation between the pygmy strength, parameters of the nuclear symmetry energy and the neutron skin thickness has been found. From the experimentally observed low-lying strength, the symmetry energy pressure p0 = 2.3 ± 0.8 MeV/fm³ and neutron skin thicknesses of 0.23 ± 0.04 fm in 130Sn and 0.24 ± 0.04 fm in 132Sn have been extracted. [ABSTRACT FROM AUTHOR]

Abstract: The future international facility FAIR (Facility for Antiprotons and Ion Research) will deliver beams of all ions up to uranium with intensities of up to 1012 ions/s. At FAIR it will be possible to perform experiments in different fields of physics. A wide range of ions with energies up to 1.5AGeV will be used for the production of fragments by projectile fragmentation/fission at the in-flight fragment separator, Super-FRS. Rare isotopes of all elements up to uranium will be produced and spatially separated within a few hundred nanoseconds, enabling the study of very short-lived nuclei. The Super-FRS is a large-acceptance device utilizing large-aperture superconducting magnets and employing multiple degrader stages to provide monoisotopic nuclear beams. It serves different experimental branches including a new storage-cooler ring system. Because of high primary beam intensity a challenging design of the target area and the components used in the first dipole stage of the Super-FRS is necessary. These efforts include high-power production targets, beam dumps to catch the remaining primary beam and radiation resistant magnets. In this contribution we present the status of the project. [Copyright &y& Elsevier]

The neutron-rich isotopes 129–133Sn were studied in a Coulomb excitation experiment at about 500 AMeV using the FRS-LAND setup at GSI. From the exclusive measurement of all projectile-like particles following the excitation and decay of the projectile in a high-Z target, the energy differential cross section can be extracted. At these beam energies dipole transitions are dominating, and within the semi-classical approach the Coulomb excitation cross sections can be transformed into photoabsorption cross sections. In contrast to stable Sn nuclei, a substantial fraction of dipole strength is observed at energies below the giant dipole resonance (GDR). For 130Sn and 132Sn this strength is located in a peak-like structure around 10 MeV excitation energy and exhibits a few percent of the Thomas-Reiche Kuhn (TRK) sum-rule strength. Several calculations predict the appearance of dipole strength at low excitation energies in neutron-rich nuclei. This low-lying strength is often referred to as pygmy dipole resonance (PDR) and, in a macroscopic picture, is discussed in terms of a collective oscillation of excess neutrons versus the core nucleons. Moreover, a sharp rise is observed at the neutron separation threshold around 5 MeV for the odd isotopes. A possible contribution of ''threshold strength'', which can be described within the direct-breakup model is discussed. The results for the neutron-rich Sn isotopes are confronted with results on stable nuclei investigated in experiments using real photons. [Copyright &y& Elsevier]

Projectile fragments separated in flight with the FRS have been injected into the storage ring ESR. Operating the ESR in the isochronous mode has enabled high-resolution mass measurements of short-lived isotopes. Already in our pilot experiments the Isochronous Mass Spectrometry (IMS) has provided accurate results for a restricted isotope range in the neighborhood of a selected isotope characterized by the best isochronous condition. In the present experiment this restriction has been overcome by precise external magnetic rigidity determination (1.5·10–4) at the dispersive midplane of the FRS. In this way the mass resolving power for neutron-rich fission fragments covering a large mass-over-charge ratio in one spectrum has been improved by up to one order of magnitude and the accuracy by more than a factor of two. [ABSTRACT FROM AUTHOR]

The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment, exotic nuclei were produced via fragmentation of 152Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution frequencies. Masses for 18 nuclides (84Zr, 92Ru, 94Rh, 107,108,110Sb, 111,112,114I, 118Ba, 122,123La, 124Ce, 127Pr, 129Nd, 132Pm, 134Sm, 137Eu) have been determined for the first time. Masses for 111,112I and 113Xe have been obtained via known α-decay energies. The experiment and first results will be presented. [ABSTRACT FROM AUTHOR]

Abstract: Fano-resonances are investigated as a new continuum excitation mode in exotic nuclei. By theoretical model calculations we show that the coupling of a single particle elastic channel to closed core-excited channels leads to sharp resonances in the low-energy continuum. A signature for such bound states embedded in the continuum (BSEC) are characteristic interference effects leading to asymmetric line shapes. Following the quasiparticle-core coupling model we consider the coupling of 1-QP (one-quasiparticle) and 3-QP components and find a number of long-living resonance structures close to the particle threshold. Results for 15C are compared with experimental data, showing that the experimentally observed spectral distribution and the interference pattern are in qualitative agreement with a BSEC interpretation. [Copyright &y& Elsevier]

The 11B(7Li, 7Be)11Be charge exchange reaction has been studied at an incident energy of 57 MeV. Spectra were measured at forward angles, θcm⩽35°. The good energy resolution (∼50 keV) allowed the identification of transitions both to the 7Be (3/2−, gs) and 7Be(1/2−, 429 keV) exit channels and hence the direct measurement of the ratio of the respective cross sections and angular distributions. Besides the bound ground and first excited state of 11Be several low lying excitations just above the neutron threshold are observed. A structure seen at E*=94 MeV with FWHM ∼7 MeV is compatible with the spin dipole resonance (SDR). The data are analysed in a many-body approach. For the projectile transitions shell model results are used. In order to account properly for the special features of the weakly bound 11Be system the target transitions are described microscopically by Hartree–Fock–Bogoliubov (HFB) and quasi-particle random phase approximation (QRPA) theory. The HFB ground state densities and the QRPA transition densities, respectively, are used in folding calculations for the optical potentials and transition form factors. Spectra and β-decay transitions strengths are reasonably well described. The measured cross section are well reproduced by one-step direct charge exchange distorted wave born approximation (DWBA) calculations. A dominance of unnatural parity transitions is found. This is explained in terms of the spin transfer behaviour of the nucleon–nucleon isovector interaction at low bombarding energy. [Copyright &y& Elsevier]

Dipole excitations of unstable short-lived nuclei has been investigated experimentally by utilizing the electromagnetic-excitation process with high-energy secondary beams. From an exclusive measurement of the neutron-decay channels, differential cross sections with respect to excitation energy, which are directly related to the photo-absorption cross section and accordingly to the dipole-strength function, have been derived. Light neutron-rich nuclei in the mass range from A = 11 to A = 23 with mass-over-charge ratios up to SHAPE="SOL" ALIGN="C" STYLE="S">AZ &ap; 2.8 have been investigated systematically. Much in contrast to stable nuclei, low-lying dipole excitations well below the giant dipole resonance region have been observed as a general phenomenon for these neutron-proton asymmetric nuclei. For the neutron-rich oxygen isotopes, for instance, low-lying E1 strength has been observed exhausting about 10% of the classical dipole sum rule below 15 MeV excitation energy. A quantitative analysis of low-lying threshold strength for loosely bound nuclei indicates that the characteristics of the dipole strength is directly related to the ground-state single-particle structure of the valence nucleon in the projectile. [Copyright &y& Elsevier]

The large angular (∼50 msr) and momentum (∼20%) acceptance spectrometer MAGNEX is under construction at the South National Laboratories INFN. In the spectrometer, positions of ions in two planes near the focal plane and their vertical positions near the target are measured. The energy resolution of about 1000 is achieved due to the use of the reconstruction of trajectories and reconstructive correction of aberrations. Main features of the spectrometer ion optics are considered.A numerical method of calculation of an arbitrary order transfer map is proposed. In this method, a transfer map is calculated using, as input, initial and final coordinates of a set of rays in an ion-optical system. The rays start at the nods of a regular multi-dimensional mesh in the particle phase space. Rays of the set are chosen automatically according to the order and dimension of the map to be calculated. Final coordinates of the rays are calculated with a regular numerical integration. The proposed is, in fact, a general (ray tracing based) method of calculation of a transfer map, of any order and dimension, for an arbitrary ion-optical system. The method has been used for numerical simulations of the reconstructive correction of aberrations in the MAGNEX spectrometer. Simulation results are considered.A C++ class library has been developed to realize the proposed transfer map calculation method. Elementary operations with vectors and maps, both being C++ objects, are realized as C++ operator functions. The map order is defined by a user at the moment of initialization of the corresponding map object. Its maximum value is limited only by an available computer memory. Computational aspects of the method are discussed in brief. [Copyright &y& Elsevier]

A low-pressure gas tracker for heavy ions is described. It is based on a drift chamber with four series of multiplying wires for energy loss measurement and underlying strips for position and angle determination. Results of tests with an α-source and with low-energy heavy-ion beams are presented. They indicate the suitability of such a detector in a wide range of experiments with heavy ions where a low energy threshold, a large solid angle, together with a precise measurement of ion trajectories and identification is needed. In particular, the application as a prototype of the focal plane detector for the large-acceptance spectrometer MAGNEX is discussed. [Copyright &y& Elsevier]

The ion optics of large-acceptance magnetic spectrometers are discussed. General techniques based on a minimum of multi-purpose magnetic elements are described. The aberrations should be minimised by shaping the entrance and exit effective field boundaries of bending magnets, the residual terms being corrected by software. Field clamps, shims and surface coils (the latter to provide kinematic compensation) are also discussed. The results and formulae which we obtain are applied to the case of the large-acceptance (∼50 msr) high-resolution magnetic spectrometer “MAGNEX” at INFN-LNS Catania. [Copyright &y& Elsevier]

A general scheme of the layout of a large acceptance magnetic spectrometer based on a wide aperture quadrupole and a multipurpose bending magnet is described. Physical quantities such as momentum resolution, focal plane size and inclination are explicitly represented as functions of transport matrix elements. In this way such quantities are directly related to the parameters defining the configuration of the spectrometer. Realistic assumptions on the shapes, the distances and the fields of the magnetic elements are taken into account in order to limit the parameter space to be spanned. A self-consistent technique simplifies the search for the best configuration and avoids the problem of ending in local minima. This technique is applied to the MAGNEX spectrometer, for which two competitive configurations, characterised by different bending angle, are found and discussed. [Copyright &y& Elsevier]

Coulomb breakup of neutron-rich Be, B, C, and O isotopes at relativistic energies (400-600 A MeV) was studied with kinematically complete measurements. The ground-state properties of these nuclei were deduced by comparing experimental data for Coulomb-dissociation cross-sections with direct-breakup model calculations. The dominant ground-state configurations of 15C, 11Be, 14B, and 23O were found to be 14C gs(0+) ⊗ νs,10Be gs(0+) ⊗ νs, 13B gs(3/2+) ⊗ νs,d, and 22O gs(0+) ⊗ νs, respectively, and 16C(2 +) ⊗ νs,d for 17C. The capture cross-section for 14C(n,γ) 15C relevant in astrophysical scenarios was measured indirectly through Coulomb dissociation. [ABSTRACT FROM AUTHOR]

A new long-lived isomeric state in the near proton dripline nucleus 125Ce has been identified with Schottky mass spectrometry at GSI. The excitation energy E * = 103(12)keV and the decay time of 193(1)s have been obtained from a single stored fully ionized 125 m Ce58+ ion. The data implies an E3 transition and a 1/2+ assignment for the spin of the isomer. [ABSTRACT FROM AUTHOR]

Abstract: High precision direct mass measurements have shown strong potential to identify and determine new nuclear isomeric states, and therefore to add intriguing new nuclear physics information by going beyond γ-ray spectroscopy. The principle and characteristic experimental results of isomer investigations in the storage ring at GSI are discussed. [Copyright &y& Elsevier]