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Neutron capture cross sections of 232T/i have been measured relative to 197Au in the energy region from 30 keV to 600 keV. The neutron source was the reaction 7Li(p, n) produced on the 4 MV Van de Graaff Accelerator of the Centre d' Etudes Nucléaires de Bordeaux (CENBG). Preliminary analysis of the measurements indicates that the cross sections are closer to the JENDL database values.

In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between {sup 36}Ca and {sup 56}Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their {beta}-decay half-life and their total {beta}-delayed proton emission branching ratio. For many nuclei, individual proton groups and {gamma} rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For {sup 50}Ni, the decay via {beta}-delayed two-proton emission could be tentatively identified. The decay of {sup 49}Ni allowed for the first time to identify the first 2{sup +} state in {sup 48}Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

PACS conv.GSI; The isotopic distributions and recoil velocities of the fission fragments produced in the spallation reaction 208Pb + p at 500 A MeV have been measured using the inverse-kinematics technique, a lead beam onto a liquid-hydrogen target, and the high-resolution spectrometer FRS at GSI. The shapes of the different distributions are found in good agreement with previously published data while the deduced total fission cross-section is higher than expected from existing systematics and some previous measurements. From the experimental data, the characteristics of the average fissioning system can be reconstructed in charge, mass and excitation energy, and the average number of post-fission neutrons can be inferred. The results are also compared to different models describing the spallation reaction. The intranuclear cascade code INCL4 followed by the de-excitation code ABLA is shown to describe reasonably well the evolution of the isotopic distribution shapes between 500 and 1000 A MeV.

A systematic investigation of the isotopic cross sections of nuclear residues produced in the reactions238U (1 A GeV)+p,d has been performed with the high-resolution magnetic spectrometer FRS at GSI. The large range of excitation energies induced in these reactions, together with the high fissility of uranium-like systems constitute an optimum scenario to study the dynamics of spallation reactions. In particular, some fundamental questions connected to the role of dissipation and the onset of a break-up stage at high temperatures can be addressed with these data.

The production of heavy nuclides from the spallation-evaporation reaction of 238U induced by 1 GeV protons was studied in inverse kinematics. The evaporation residues from tungsten to uranium were identified in-flight in mass and atomic number. Their production cross-sections and their momentum distributions were determined. The data are compared with empirical systematics. A comparison with previous results from the spallation of 208Pb and 197Au reveals the strong influence of fission in the spallation of 238U.

In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip-line nucleus Fe45 has been studied after projectile fragmentation of a Ni58 primary beam at 75 MeV/nucleon impinging on a natural nickel target. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon strip detector on an event-by-event basis. The decay-energy spectrum of Fe45 implants shows a distinct peak at (1.06+/-0.04)MeV with a half-life of T1/2 = (4.7+3.4-1.4)ms. None of the events in this peak is in coincidence with beta particles which were searched for in a detector next to the implantation detector. For a longer correlation interval, daughter decays of the two-proton daughter Cr43 can be observed after Fe45 implantation. The decay energy for Fe45 agrees nicely with several theoretical predictions for two-proton emission. Barrier-penetration calculations slightly favour a di-proton emission picture over an emission of two individual protons and point thus to a He2 emission mode.

The production cross sections and the kinematical properties of primary residual nuclei have been studied in the reaction 208 Pb(1 A GeV)+d. Isotopic distributions were measured for all elements from titanium ( Z =22) to lead ( Z =82). The measured kinematical properties of the residues were also used to disentangle the relevant reaction mechanisms, spallation–evaporation and spallation–fission. The fragment separator FRS at GSI, Darmstadt, was used to separate and identify the reaction products. The measured quantities are important for the design and planning of future radioactive-beam facilities and accelerator-driven systems. The measured data of the present work are comprehensively compared with the experimental data from the reaction 208 Pb(1 A GeV)+p.

A large experimental program has been initiated at GSI to determine the production cross sections of heavy residues in relativistic heavy-ion collisions. The complete isotopic distributions of spallation–evaporation residues of the reactions induced by 1 GeV protons and 2 GeV deuterons in 238U are presented. The primary reaction products were fully identified in mass and atomic number prior to beta decay by using the fragment separator FRS. These data provide basic information to estimate the intensities of radioactive nuclear beams to become available in future RNB facilities using isotope separation on-line (ISOL) or in-flight separation techniques.

With the inverse kinematics method, the reaction mechanism which leads to the formation of light nuclides was investigated with a 1 A GeV 238 U beam impinging on a liquid H 2 target. Isotopes of all elements with Z ⩾6 were unambiguously identified, and the velocity of every produced nuclide was measured with great precision. Results show that very asymmetric fission of uranium nuclei produces neutron-rich isotopes of elements down to around charge 10. When uranium interacts with heavier nuclei the features of the reaction change drastically: while fission is the main mechanism for the production of light masses in 1 A GeV 238 U on H 2 , projectile fragmentation plays a dominant role in 1 A GeV 238 U on Ti leading to the formation of stable or neutron-deficient isotopes of all elements.

The production of primary residual nuclei in the reaction 1 A GeV 208Pb on proton has been studied by measuring isotopic distributions for all elements from titanium (Z=22) to lead (Z=82). Kinematical properties of the residues were also determined and used to disentangle the relevant reaction mechanisms, spallation (projectile fragmentation) and fission. The fragment separator FRS at GSI, Darmstadt, was used to separate and identify the reaction products. The measured production cross sections are highly relevant for the design of accelerator-driven subcritical reactors and for the planning of future radioactive-beam facilities.

Spallation residues produced in 1 GeV per nucleon ${}^{208}\mathrm{Pb}$ on proton reactions have been studied using the Fragment Separator facility at GSI. Isotopic production cross sections of elements from ${}_{61}\mathrm{Pm}$ to ${}_{82}\mathrm{Pb}$ have been measured down to 0.1 mb with a high accuracy. The recoil kinetic energies of the produced fragments were also determined. The obtained cross sections agree with most of the few existing gamma-spectroscopic data. The data are compared with different intranuclear-cascade and evaporation-fission models. Drastic deviations were found for a standard code used in technical applications.

In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a 36 Ar primary beam at 95 MeV/nucleon to produce the isotope 24 Si. The beta decay half-life of 24 Si has been determined to be T 1/2 = (140 ± 8) ms, in agreement with earlier measurements. In addition to the decay of the isobaric analog state, several proton peaks are observed for the first time allowing to identify most of the Gamow-Teller transitions to unbound states and to present a partial decay scheme for 24 Si. These results are compared with shell-model predictions.

23Si isotopes have been produced as projectile fragments of a 36Ar primary beam at 95 MeV/nucleon at the LISE3 spectrometer of GANIL. After implantation in a detector telescope, β-delayed one-proton and β-delayed two-proton emission has been observed. The main one-proton peaks are at (1.32±0.04)MeV, (2.40±0.04)MeV, and (2.83±0.06)MeV. The total decay energy for the β2p decay is (6.18±0.10)MeV for the decay to the ground state and (5.86±0.10)MeV for the decay to the first excited state in the daughter nucleus. However, energetically possible decays via βpα and β3p emission have not been identified. The spectra allowed us to determine the excitation energy of the isobaric analogue state in 23Al. This enabled us to calculate the coefficients of the T = 5/2 isobaric multiplet mass equation for A = 23. The mass excess of the 23Si ground state was deduced. This value is compared to different theoretical predictions. Additionally, we determined the branching ratios for the different decay branches. A half-life measurement yielded T1/2 = (40.7±0.4)ms.

In an experiment at the LISE3 facility of GANIL, we produced the proton-rich isotope 22Al by the fragmentation of a 36Ar primary beam at 95 MeV/nucleon. After implantation in a detector telescope, the decay of 22Al via β-delayed proton emission, β-delayed two-proton emission as well as, for the first time, via β-delayed α emission has been studied. An α peak has been observed at (3.27 ± 0.04) MeV with a branching ratio of (0.31 ± 0.09) %. The comparison of the different decay channels to those of the mirror nucleus 22F and to shell-model calculations favor a 3+ state as being the ground state of 22Al. A half life of T1/2 = (59 ± 3) ms has been measured.

In an experiment at the SISSI/LISE facility of GANIL, we used the projectile fragmentation of a ${}^{78}\mathrm{Kr}$ primary beam at 73 MeV/nucleon to produce new isotopes of astrophysical interest. We obtained clear evidence for the existence of the five new isotopes ${}^{60}\mathrm{Ga}$, ${}^{64}\mathrm{As}$, ${}^{69,70}\mathrm{Kr}$, and ${}^{74}\mathrm{Sr}$. However, we did not find any evidence for ${}^{69}\mathrm{Br}$, whereas comparable nuclei were observed with more than 1000 counts. The isotope ${}^{69}\mathrm{Br}$ is thus deduced to be a proton-unbound nucleus with a half-life shorter than about 100 ns. The influence of these results on our understanding of the astrophysical RP process is discussed.

At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments have been identified and their charge-changing probabilities in targets of CH2, C, Al, and Pb have been determined. We describe the results for the total charge-changing cross sections in this first paper, whereas a second article deals with the partial charge-changing cross sections. At the drip line, the measured charge-changing cross sections exhaust close to 100% of the total interaction cross sections as calculated with semiempirical models. The measurements at the proton drip line with low-Z targets indicate that only a very small increase of the cross sections may be observed, whereas the measurements with a lead target show that no significant increase of the total charge-changing cross sections is present which would be a hint for low-lying dipole strength. Our experimental data are compared to Glauber-type calculations.

Total nuclear charge-changing cross sections σΔz in a CH2 target were measured for 54 isotopically identified secondary beams around A = 60 produced from a 1A·GeV86Kr beam via projectile fragmentation. With secondary beams between T z = 1 2 and −3, the isospin dependence of σΔz was investigated systematically. Contrary to the predictions of so-called overlap formulae, the σΔz values are not a function of the projectile mass alone, but are found to depend on the projectile isospin. A comparison of the data with the predictions of the statistical abrasion model reveals that this behaviour can be understood by the combined influence of the abrasion and the ablation phase in relativistic heavy-ion collisions. On the basis of this improved understanding, previous findings of anomalously large cross sections of secondary-reaction products are discussed.

Using a primary beam of $^{58}\mathrm{Ni}$ at 650 MeV/nucleon impinging on a beryllium target, production cross sections of proton-rich fragments from projectile fragmentation have been measured at the projectile-fragment separator FRS at Gesellschaft f\"ur Schwerionenforschung Darmstadt m.b.H. The experimental data ranging from nickel to scandium for isotopes close to stability as well as for fragments at the proton drip line are compared to predictions of the microscopic ISApace code, to calculations with a revised abrasion-ablation model and with the statistical abrasion model, and to the results of the empirical parametrization EPAX. Besides these systematic measurements, evidence for the particle stability of $^{50}\mathrm{Ni}$ has been found for the first time, whereas the nuclei $^{49}\mathrm{Co}$ and $^{54}\mathrm{Cu}$ are shown to be unbound. These observations are compared to mass predictions.

Using the magnetic spectrometer SPES I at SATURNE, energy-loss measurements have been performed for projectiles of 40 Ar (401 MeV/u), 36 P (362 MeV/u), 15 N (149 MeV/u), 11 Li (131 MeV/u) and 8 Li, 9 Li (130 MeV/u) in carbon, aluminum and lead targets. The experimental results are compared to calculations based on a modified relativistic Bethe formula and to a semiempirical formula using a Z 2 scaling law for the stopping power and an effective charge parametrization for the heavy ions.

Fission fragments of 1A GeV{sup 238}U nuclei interacting with a deuterium target have been investigated with the Fragment Separator (FRS) at Gesellschaft fuer Schwerionenforschung (GSI) by measuring their isotopic production cross sections and velocities. Results, along with those obtained recently for spallation-evaporation fragments, provide a comprehensive analysis of the spallation nuclear productions in this reaction. Details about the experimental performance, data reduction and results are presented.

Isotopic production cross sections and momentum distributions of 602 residual nuclei produced in the collision of $^{238}\mathrm{U}$($1A$ GeV) with deuterium have been measured. These data are relevant for a better understanding of spallation reactions for use as neutron sources for accelerator-driven systems or to produce radioactive nuclear beams. Access to primary residue production makes it possible to study the main reaction mechanisms involved: intranuclear cascade, particle evaporation, and fission. The characteristics of the reaction investigated and the high fissility of the $^{238}\mathrm{U}$ and the dinucleon projectile system are discussed and compared with other available experimental data.

PACS; International audience; The production of residual nuclei in p + Fe collisions has been measured at GSI on the FRS facility by means of the reverse kinematic techniques at 300, 500, 750, 1000 and 1500 MeV/A. The cross-sections larger than 0.01 mb of all isotopes with Z larger than 8 have been obtained. Velocity distributions were also measured. Comparisons to models describing spallation reactions and some empirical formulae often used in astrophysics are presented. These data are directly used to calculate impurety production and DPAs in a thin window as foreseen in spallation sources or accelerator-driven systems

Experiment at the GANIL / LISE3 facility; International audience; According to most mass models, several of the best candidates for two‐proton radioactivity lie in the A = 50 mass region, at the proton drip‐line. Recent experiments using the fragmentation of a 58Ni beam allowed us to reach this region and observe some of these candidates, like 45Fe and 48Ni. During an experiment at the GANIL / LISE3 facility helded in 2000, we could identify 22 events of implantation of 45Fe nuclei. The energy distribution of the corresponding decay events shows a clear peak at (1.14 ± 0.04) MeV that could be assigned to the direct 2‐proton emission from the ground state. This energy is in very good agreement with several theoretical predictions, and no coincident β particle has been observed experimentally. A half‐life of (4.7−1.4+3.4) ms has been measured for the decay of 45Fe.

The isotopic production cross sections of heavy residues in relativistic heavy-ion collisions have been investigated in inverse kinematics. The primary reaction products were fully identified in mass and atomic number prior to beta decay using the fragment separator FRS. The huge collection of data obtained helps in the understanding of the two main reaction mechanisms involved: fragmentation and fission. These data provide basic information for future radioactive ion beam facilities and for technical applications like intense neutron sources by means of spallation targets.

An experiment was performed at GANIL using a high-intensity 58 Ni beam at 74.5 MeV/nucleon on a nickel target. The projectile fragments produced in the high-acceptance SISSI device were selected in the LISE3 spectrometer using the Wien filter. The detection setup performed an unambiguous identification of four 48 Ni implantation events. A lower limit of its half-life of the order of 0.5 μs and an estimate of the production cross section of about 0.05 pb were deduced. In addition, a few tens of 45 Fe and 49 Ni nuclei were implanted, which may give information on their decay modes. Besides, 48 Ni and 45 Fe are very good candidates for two-proton radioactivity, still to be observed.

The production cross sections and the kinematical properties of primary residual nuclei have been studied in reactions 197Au+p, 208Pb+p,d, 238U+p,d, and 238U+208Pb at energies around 1 A GeV. The measured kinematical properties of the residues were also used to disentangle the relevant reaction mechanisms, spallation-evaporation and spallation-fission. The fragment separator FRS at GSI, Darmstadt, was used to separate and identify the reaction products. The measured quantities are important for the design of accelerator-driven subcritical reactors and for the planning of future radioactive-beam facilities.

In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich zinc isotopes 55,56Zn have been observed for the first time. The experiment was performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a nickel target. The identification of 55,56Zn opens the way to 54Zn, a good candidate for two-proton radioactivity according to theoretical predictions., 2 pages, 1 figure, accepted for publication in Eur. Phys. J. A

The neutron capture cross section of {sup 232}Th has been measured relative to {sigma}(n, {gamma}) for {sup 197}Au and {sigma}(n,f) for {sup 235}U in the energy range from 60 keV to 2 MeV. Neutrons were produced by the {sup 7}Li(p,n) and T(p,n) reactions at the 4-MV Van de Graaff Accelerator of CEN Bordeaux-Gradignan. The activation technique was used, and the cross section was measured relative to the {sup 197}Au(n,{gamma}) standard cross section up to 1 MeV. The characteristic gamma lines of the product nuclei {sup 233}Pa and {sup 198}Au were measured with a 40% high-purity germanium detector. Above this energy, the reaction {sup 235}U(n,f) was also used as a second standard, and the fission fragments were detected with a photovoltaic cell. The results, after applying the appropriate corrections, indicate that the cross sections are close to the JENDL-3 database values up to 800 keV and over 1.4 MeV. For energies in the intermediate range, our values are slightly lower than those from all the libraries.

Decay studies of very neutron-deficient nuclei ranging from 39Ti to 49Ni have been performed during a projectile fragmentation experiment at the GANIL/LISE3 separator. For all nuclei studied in this work, 39,40Ti, 42,43Cr, 46Mn, 45,46,47Fe and 49Ni, half-lives and decay spectra have been measured. In a few cases, gamma coincidence measurements helped to successfully identify the initial and final states of transitions. In these cases, partial decay scheme are proposed. For the most exotic isotopes, 39Ti, 42Cr, 45Fe and 49Ni, which are candidates for two-proton radioactivity from the ground state, no clear evidence of this process is seen in our spectra and we conclude rather on a delayed particle decay., Comment: 12 pages, 15 figures, submitted for publication in Eur. Phys. J. A

This contribution reports on the cross section measurements performed at GSI on the isotopic distribution of the residual nuclides of spallation reactions in inverse kinematics. The fragment separator (FRS) was used to select and identify the reaction products, and the full (Z,N) map was measured above the production limit of 0.1 mb. The high resolution of the spectrometer allowed to determine the velocity distributions of all products. These data are relevant for the design of accelerator-driven subcritical reactors. They are also of the highest importance to improve the understanding of the spallation mechanism.

If simplified, every information retrieval problem can be solved when the information need implied by its expression has been identified. We are interested in the criteria used in realising a good information retrieval problem expression. We have listed these criteria through some principles and maxims which first characterized the communication between two persons are applied. We choose to use the gricean maxims because they are the most favoured for this type of situation. Secondly, we have tried to identify some others principles that can be used to realise a good information retrieval problem expression. The principles by Grice can not resolve all forms of error associated with this particular form of communication. In our work, we defined three other principles namely: adhesion principle, reformulation principle, memorization principle. We give some examples of situations where the principles we have formulated are not applicable and the consequences. We present the possible applications of our new model: MIRABEL, which can help in the description of information retrieval problem from. It also compels its user to use essential good expression principle implicitly.

Spallation experiments in inverse kinematics have been performed at GSI. The momentum distributions and the isotopic production cross sections have been measured. The data are relevant for the design of accelerator-driven subcritical reactors.

A relativistic primary beam of 58Ni from the SIS synchrotron at GSI was used to produce proton-rich isotopes in the titanium-to-nickel region by projectile fragmention at the FRS. We report here on the first observation of the Tz=−7/2 nuclei 45Fe and 49Ni. In addition, the new isotope 42Cr (Tz=−3) was identified. This opens the route to the yet unobserved doubly-magic nucleus 48Ni.

β-delayed one- and two-proton and α spectroscopic studies of the neutron-deficient nuclei 22,23,24Si and 22Al produced in projectile fragmentation of a 36Ar primary beam at 95 MeV/u have been performed at GANIL. Isotopes of interest were analyzed using the LISE3 spectrometer and were implanted in a telescope made of silicon detectors and a micro-strip gaseous counter where decay particles were detected.

In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a 36 Ar primary beam at 95 MeV/nucleon to produce neutron-deficient isotopes in the Al-Si region. The selected isotopes were implanted in a detector telescope, where their decay particles were observed. We report here on the study of the βp, β2p, and βα decay of the isotopes 22,23,24 Si and 22 Al. Beta-decay half-lives have been measured. The ground-state mass excess of 23 Si has been determined. Partial decay schemes are presented on the basis of the transitions associated with the observed decay peaks.

In an experiment performed at the FRS of GSI, we measured total interaction cross sections for 7 Be, 8 B, and 9 C, one-proton-removal cross sections for 8 B and 9 C as well as two-proton-removal cross sections for 9 C on targets ranging from carbon to lead at an energy of 285 MeV/nucleon. In addition, we performed measurements at 142 MeV/nucleon for 8 B. The experimental results are compared to different calculations. Glauber-type calculations with different model·density distributions show that, down to incident energies of about 50 MeV/nucleon, total interaction cross-section measurements with light targets are not sensitive to an extended proton distribution in 8 B. However, at lower incident energies, a tail in the proton density distribution is needed to explain the total interaction cross sections. Total interaction cross-section measurements with high-Z targets in the present experiment show a significant increase of the cross sections due to low-lying electromagnetic strength.

Expérience GANIL, SISSI/LISE; In an experiment at the SISSI/LISE facility of GANIL, we produced proton-rich isotopes in the selenium-to-strontium region by projectile fragmentation of a 78Kr primary beam at 73 MeV/nucleon. The emission of P-delayed protons from h7Se, 7'Kr, and 75Sr was observed for the first time and the corresponding branching ratios were determined. The proton energy spectra were compared to predictions of a statistical model. The half-lives of 67 Se, 7' Kr, and 75Sr were deduced from the time characteristics of the observed proton activity. The half-life of 75Sr was measured for the first time. For “Se and 7'Kr, the obtained half-lives are compared to previous measurements.

This paper reviews two experiments performed at GSI and GANIL. Using a primary beam of 58 Ni at 650 MeV/nucleon impinging on a beryllium target, production cross sections of proton-rich fragments from projectile fragmentation have been measured at the projectile-fragment separator FRS at GSI. The production rates measured demonstrate that counting rates much higher than expected can be obtained at the proton drip line. The results from spectroscopy measurements show that no Thomas-Ehrmann effect is present in our data which means that the decay energies and masses can be well predicted by using e.g. the IMME. The secondary reactions evidence a slight increase of the interaction cross sections when approaching the proton drip line. Finally, in an experiment performed at the SISSI/LISE facility at GANIL using a 78 Kr primary beam, we have observed the 5 new isotopes 60 Ga, 64 As, 69,70 Kr, and 74 Sr. However, we have not found any evidence for 69 Br which was reported to be observed with a few counts at MSU. These new findings change our understanding of the path and of the ending point of the rp process.

A method for measuring the cross sections for the neutron removal from relativistic secondary projectiles by means of a two-stage magnetic spectrometer is presented. Its application to the 1n- and 2n-removal from 56 Ni and 52 Fe at 470 A ·MeV in an aluminum target is described. The results are compared to the intranuclear-cascade plus evaporation model and to the statistical abrasion-ablation model. The influence of the nuclear surface on the few-nucleon removal reactions is discussed. The neutron-removal cross sections are combined with total charge-changing cross sections to obtain the total interaction cross sections of 56 Ni and 52 Fe.

We have measured production cross-sections of the new neutron-rich isotopes58Ti,61V,63Cr,66Mn,69Fe,71Co and neighbouring isotopes that have been identified as projectile fragments from reactions between a 500 MeV/u86Kr beam and a beryllium target. The isotope identification was performed with the zero-degree magnetic spectrometer FRS at GSI, using in addition time-of-flight and energy-loss measurements. The experimental production cross-sections for the new nuclides and neighbouring isotopes are compared with an empirical parametrization. The resulting prospects for reaching even more neutron-rich isotopes, such as the doubly-magic nuclide78Ni, are discussed.

Neutron-deficient isotopes with Z=21 to 26 have been produced as projectile-like fragments of an intense 58Ni GANIL beam of 69 MeV/nucleon. The nuclei selected by the upgraded LISE3 spectrometer were identified and implanted in a silicon detector telescope. The 43Cr, 47Fe and 46Fe isotopes were identified for the first time whereas 45Fe, 45Mn, 44Mn and 42V were not observed, indicating probable instability of these nuclei against particle emission. Measurements of the half-lives of 43Cr and 46Mn have been performed and the analysis of their measured beta-delayed proton spectra has given, through the isobaric multiplet mass equation, an empirical estimation of their masses. Half-lives of 44Cr, 43V, 47Fe and 46Fe have also been measured. A discussion of various mass predictions for nuclei at the proton drip-line is given.

A major achievement in the study of nuclei far from stability has been the observation of new radioactive modes 1. Besides broadening the scope of reported nuclear processes, new radioactive modes provide specific structure information. Among them, direct emission of more than one nucleon carries unaltered informations on nuclear correlations. The simplest case is the long-predicted and not yet observed: direct two-proton radioactivity. At the proton drip-line, it might happen that a nucleus is bound by a one-proton emission but is able to decay by the direct emission of two protons. This process, discussed long time ago by Goldanski 2 and Janecke 3 is governed by barrier penetration.

18 C has been produced as a projectile fragment in the interaction of a 60 MeV/u 22 Ne beam with a thick beryllium + carbon target. Using the LISE spectrometer of GANIL tuned according to the PFIS method allowed an unprecedented measurement of its β-delayed γ spectroscopy, along with redetermination of half-life and β-neutron branching ratio. A partial decay scheme is proposed. A comparison with theoretical predictions provides a qualitative understanding of the decay of 18 C.

Beta-delayed two-proton decay is reported for the T z = − 5 2 isotopes 31 Ar and 27 S wnich were produced by fragmentation of 36 Ar at 85 MeV/u. The two-proton nature of this decay is established on the basis of the number of events which trigger two detectors or more in a silicon-detector telescope. The proton energy spectra give experimental values for the daughter energy levels and for the branching ratios. The deduced values of the 31 Ar and 27 S masses are discussed and compared with mass predictions. For both nuclei, other channels like β3p and βpα are to be searched for since the observed β2p and βp branches do not fully account for the total decay width of the isobaric analog states in the daughter nuclei. Partial decay schemes are proposed for 31 Ar and 27 S.

Projectile fragments were produced with a 403 MeV/u 40Ar beam from the SATURNE accelerator in a thick carbon target. By use of the spectrometer SPES I in combination with a shaped energy-degrader, a clean secondary beam of 36P was separated. The results of this first application of a momentum-loss achromat to relativistic projectile fragments confirm model calculation published previously. In particular, several experimental values for the energy loss and the energy-loss straggling have been found to agree with the predictions. The amount of cross-contaminants originating from secondary reactions proved to be very small. As an additional separation tool a range telescope has been successfully tested.

Particle- γ and particle-K X-ray coincidence methods have been used to identify the residual nuclei in the asymmetrical heavy-ion reactions 14 N + 169 Tm and 14 N + 174 Yb. The usefulness of this technique, at the intermediate bombarding energy of 30 MeV / n, is proved. The results are compared with the incomplete fusion reaction model. The difference observed between the experimental and theoretical charge distributions are tentatively attributed to the sequential decay of the projectile-like fragments not taken into account by the model.

The thirteen above-listed isotopes have been produced at GANIL by fragmentation of a40Ar beam at 60 MeV/nucleon. The LISE spectrometer allowed us to isotopiaally separate these nuclei. Beta delayed gamma spectroscopy was carried out for the first time for eleven isotopes and additional information was obtained for another two.

Beta-delayed proton radioactivity has been observed for the 28 S isotope ( T z = −2), produced by projectile fragmentation of 85 MeV/u 36 Ar. The measured half-life of 28 S is 125 ± 10 ms. Energy spectra of beta-delayed protons have been measured. The lowest T = 2 state in the daughter nucleus 28 P has been located at an excitation energy of 5900 ± 21 keV. A comparison of the experimental data to the quadratic form of the isobaric multiplet mass equation shows that the energies of the five T = 2 states of the A = 28 quintet are well represented by that relation. Shell-model predictions for the half-life of 28 S and the location and decay properties of the lowest T = 2 state of 28 P are in good agreement with experimental data.

A new method for the isotopic separation of projectile fragments is exposed. The application to the LISE spectrometer at GANIL provided radioactivity data on light neutron‐rich nuclei (mass range 14–40). The observation on 17B of the beta‐delayed four neutron decay mode is reported for the first time.

The isotopic separation of intermediate-energy (30 to 100 MeV per nucleon) heavy-ion projectile fragments is theoretically and experimentally investigated. Physical separation of nuclides is achieved through magnetic analysis (AZ sensitivity) and differential stopping-power effects (Z−2 sensitivity). Depending on the specific case, a complete mass and charge separation may be achieved or a few nuclides may be selected simultaneously. The projectile fragments isotopic separation method described allows us to obtain an experimental mass separation AΔA ≈ 100. Simple formulae are given to determine the optimum factors for the best separation and transmission of the device. First applications to the spectroscopy of exotic nuclei lead to the new observation of the beta decay of 37P at GANIL and 15B at CERN.