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The γ-ray de-excitations following the β-decay of 83Ga and the β-n decay of 84Ga have been studied. The radioactive species were produced using the PARRNe on-line mass-separator installed at the IPN Orsay Tandem accelerator. Two γ-lines were attributed to 83Ge with the aid of β-γ and γ-γ coincidences. The Z identification of the γ-lines was provided by time analysis of a buid-up/decay cycle. The excited levels of 83Ge can be explained by the coupling of the single neutron state ν2d 5/2 to the first 2+ excitation of the 82Ge core.

In the framework of the EURISOL project, the production of neutron-rich isotopes of rubidium and cesium has been studied. The intensities of mass-separated beams of rubidium and cesium isotopes generated from a thick 238 UC x target connected to a surface ionizer have been measured. The release properties of 140 Cs and 91 Rb have been investigated. The obtained results allowed us to determine the relative fission yields of rubidium and cesium isotopes with high accuracy.

The PARRNe (Production d'Atomes Radioactifs Riches en Neutrons) experimental program has been part of the recent R&D efforts for the design of the SPIRAL2 project at GANIL. The PARRNe2 set-up installed at IPNOrsay allows the use of the Tandem as a deuteron driver in order to produce mass separated fission fragment beams. The measured fission fragment yields proved to be high enough to undertake a series of beta-decay experiments dedicated at studying the structure of proton-deficient nuclei close to N=50. We report here on two such experiments, the first being dedicated at the observation of the decay of 83Ga->83Ge (Z=32, N=51), 84Ga->84Ge (Z=32, N=52) and the second of the decay of 81Zn->81Ga (Z=31, N=50) allowing for the fist time the identification of a few gamma lines with transitions in the daughter nuclei thus providing the material for a preliminary glimpse of their structure.

The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time.

In the framework of the PARRNe program (Production d’Atomes Radioactifs Riches en Neutrons) of IPN Orsay, various techniques are currently used to characterize the release properties of elements of interest from a UCX target. On-line studies have been carried out with two plasma ion sources: a Nier–Bernas and a hot plasma ISOLDE-type (the ISOLDE collaboration kindly supplied us a MK5 ion source for these studies). In parallel, the analysis of the chemical and structure properties of some UCX samples as function of heating conditions has been carried out. Such data are essential to determine optimal conditions for the production of isotopes by the isotope separator on-line (ISOL) technique. First results are presented here for Kr and Ag. Investigations for other kinds of fission targets are planned.

The release properties of UCx and molten U thick targets associated with a Nier–Bernas ion source have been studied. Two experimental methods are used to extract the release time. Results are presented and discussed for Kr, Cd, I and Xe.

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

The latest results of the research and development program Production d'Atomes Radioactifs Riches en Neutrons (PARRNe) at Institut de Physique Nucleaire (IPN) Orsay are presented. The production of neutron rich isotopes by fast neutron induced fission in a liquid depleted uranium target was measured. A comparison of the production rates with a uranium carbide (UCx) target is given.

NESTER

We studied $\ensuremath{\beta}$-delayed proton and $\ensuremath{\gamma}$ emission from ${}^{40}\mathrm{Ti}$ decay. We found ${t}_{1/2}=52.7\ifmmode\pm\else\textpm\fi{}1.5 \mathrm{ms}$ and observed 28 proton groups that we organized into a ${}^{40}\mathrm{Ti}$ decay scheme with 21 branches. The reduced transition strengths of these decay branches were then used to compute the neutrino detection efficiency of the ICARUS liquid argon time-projection chamber. We found ${}^{40}\mathrm{Ar}(\ensuremath{\nu},e)$ cross sections (for an electron energy threshold $W=5 \mathrm{MeV}$) of $(14.0\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}43} {\mathrm{cm}}^{2},$ $(75.1\ifmmode\pm\else\textpm\fi{}1.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}43} {\mathrm{cm}}^{2},$ and $(3.2\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}41} {\mathrm{cm}}^{2}$ for ${}^{8}\mathrm{B}$ neutrinos, hep neutrinos, and supernova neutrinos characterized by a temperature of 4.5 MeV.

Seven previously unobserved neutron-rich isotopes ( 209 Hg, 210 Hg, 211 Tl, 212 Tl, 218 Bi, 219 Po and 220 Po) have been identified among the fragmentation products of a 1000 MeV/nucleon 238 U beam incident on a beryllium target. The γ -ray decays of 9 known and 4 new μ s-isomers in nuclei around 208 Pb were also observed. Production cross sections and probabilities for populating isomeric states in the fragmentation reaction were determined and compared with a simple model based on the statistical abrasion-ablation approach.

A Coulomb excitation experiment has been performed in order to study the subshell closure atN = 40 for neutron-rich nuclei. This subshell effect is thought to be enhanced when largeN/Z ratios are encountered. Therefore, theZ = 2868Ni is of particular interest in order to test this behaviour. Some experimental information is already available for68Ni at low excitation energy: a 0+ 2 isomer, a 2+ state and a long-lived 5- state. The high energy of the 2+ state suggests the shell closure though its reduced transition probabilityB(E2) has never been mesured. The nuclei68Ni,70,72Zn,76Ge have been produced in the fragmentation of a86Kr beam at 60 MeV/A. The selection of these secondary beams has been performed by LISE3 spectrometer at GANIL. Performances of the detector system “Château de Cristal” and preliminary results on reduced transition probabilitiesB(E2) are presented and discussed.

The short-lived isomeric states in the T{sub Z}=1 nuclei, {sup 94m}Pd [T{sub 1/2}=0.6(1) {mu}s] and {sup 96m}Ag [T{sub 1/2}=0.7(2) {mu}s], were identified among the fragmentation products of the {sup 112}Sn (63A MeV) + {sup nat}Ni (93.5 mg/cm{sup 2}) reaction at GANIL. The separation and identification of the reaction products was done by means of the Alpha and LISE3 magnetic spectrometers combined with time-of-flight, energy-loss, and total kinetic energy measurements. Evidence for isomeric states in {sup 80}Y, {sup 98}Cd, and {sup 102}Sn was also obtained. {copyright} {ital 1997} {ital The American Physical Society}

The neutron-rich isotopes $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ and $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are produced by fragmentation of a 64.5 MeV/nucleon $^{65}\mathrm{Cu}^{26+}$ beam in a 90 mg/${\mathrm{cm}}^{2}$ $^{9}\mathrm{Be}$ target. Following particle identification by energy loss and time of flight, the radioactive decay was observed by \ensuremath{\beta} singles and \ensuremath{\beta}\ensuremath{\gamma}-coincidence measurements. The results obtained for $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are compared to previous results, whereas the decay of the $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ isotopes is studied here. \ensuremath{\gamma}-ray intensities and energies are estimated. The new experimental results are compared to quasi-random-phase-approximation predictions. \textcopyright{} 1996 The American Physical Society.

Resonances in the unbound nucleus N-11 have been studied, using the resonance scattering reaction C-10+p. The data give evidence for three states above the C-10+p threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1/2(+), 1/2(-), and 5/2(+) arising from the shell-model orbitals 1s(1/2), Op(1/2), and Od(5/2). A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3/2(-) in Be-11 shifted down in energy. This shift would suggest a large radius of the potential.

The reaction cross section for {sup 8}B and {sup 7}Be and the breakup cross section for {sup 8}B on silicon have been measured for incident energies between 10 and 40 MeV/nucleon with a stack of silicon detectors. Secondary {sup 8}B and {sup 7}Be beams were obtained by use of the LISE spectrometer at GANIL. The stack of silicon detectors had the multiple purpose of slowing down the incident secondary beams, identifying the reaction products, and measuring their energy. The separate contributions of diffraction dissociation and absorption to the breakup have been determined. The parallel momentum distribution of {sup 7}Be resulting from the breakup of {sup 8}B has also been determined. The data are compared to theoretical calculations. {copyright} {ital 1996 The American Physical Society.}

The energy spectrum of $^{14}\mathrm{C}$ ions emitted from $^{223}\mathrm{Ra}$ sources implanted at ISOLDE has been measured with the spectrometer SOLENO. The highest statistics (899 events) and the best energy resolution (90 keV) obtained so far in cluster decay allow a real spectroscopic study. Hindrance factors for transitions to the ground state and first excited state in $^{209}\mathrm{Pb}$, and limits for the next three low-lying states, hae been determined. The data can be explained by a parent wave function containing mainly a ${\mathit{i}}_{11/2}$ spherical component.

The quasielastic scattering of the exotic nucleus $^{8}\mathrm{B}$ on a $^{12}\mathrm{C}$ target has been studied at an energy of 320 MeV and compared with that of $^{7}\mathrm{Be}$ at the same velocity. The quasielastic scattering of $^{12}\mathrm{C}$ + $^{12}\mathrm{C}$ at 20 MeV/nucleon, also performed as a secondary beam experiment, was used to check the data reduction method. The results are interpreted in terms of a semimicroscopic double folding model and coupled-channels calculation. The difference in the total reaction cross section (8%) between $^{8}\mathrm{B}$ and $^{7}\mathrm{Be}$ is consistent with the measured one proton removal cross section and corresponds to an increase in the interaction radius of 4%. The existence of a substantial proton halo in $^{8}\mathrm{B}$ is not supported by the present data.

Six new neutron-deficient nuclei 103Sb, 104Sb, 98In, 91Pd, 89Rh and 87Ru have been identified among the products of quasi-fragmentation of a 112Sn beam (63 MeV/nucl.), in addition to the previously reported 100Sn and 102Sn. Decays of over forty short-lived ( T 1 2 from ≈50 ns to 70μ s ) isomeric states including new isomer 66mAs were observed in the same reaction.

Eine Reihe von Meteoriten enthalten winzige Einschlusse von Ca-Al-reichen Mineralen mit ungewohnlichen isotopischen Zusammensetzungen, die wahrscheinlich auf Kondensate von protosolarem Sternenstaub zuruckzufuhren sind. Um den nukleosynthetischen Ursprung dieser Isotopenanomalien zu klaren, ist eine detaillierte Kenntnis der Kernstruktur ihrer neutronenreichen „Progenitor”-Nuklide erforderlich. Hierzu am Fragmentseparator LISE des GANIL durchgefuhrte Experimente zeigten eine unerwartete Abschwachung der magischen N = 28-Neutronenschale unterhalb von 48Ca. Dieser Effekt liefert den kernpyhsikalischen Schlussel zum Verstandnis der astrophysikalischen Bedingungen bei der Bildung der Ca-Ti-Cr-„FUN”-Anomalien in Supernovaexplosionen. „FUN” steht fur „Fractionation and Unknown Nuclear effects”.

The β-decay of 20Mg was investigated. A secondary beam of 20Mg ions, produced in reactions between a 95 A·MeV24Mg-beam and a natNi-target, was isotopically separated by means of the LISE3 spectrometer at GANIL. This secondary beam was implanted into a silicon detector array surrounded by germanium γ-detectors. The β-delayed proton and γ-ray data, measured for this short-lived nucleus ( T 1 2 = 95 ± 3 ms ), were incorporated into an improved 20Mg→20Na decay scheme. The 2645 keV level in 20Na is of importance for the breakout from the astrophysical hot CNO-cycle and the onset of the rapid proton capture process via the reaction 19Ne(p,γ)20Na. An upper limit of 0.1% for the β-decay feeding of the 2645 keV level and a lower limit for the corresponding log ft value of 6.24 were determined. The implications of this result for the spin and parity assignment of the 2645 keV state are discussed. By comparing the 20Mg β-decay into the proton-unbound 3001 keV state in 20Na and the isospin-mirrored decay into the particle-bound 3488 keV level in 20F, an asymmetry ft + ft − − 1 = 1.69 −0.65 +0.86 was observed. The comparison of the experimentally determined B(GT) values for the Gamow-Teller β-decay of 20Mg with a calculation performed in a full sd-shell model space yields an overall quenching of the Gamow-Teller strength of 0.84, corresponding to an observed fraction of 71% of the calculated strength. The measured Gamow-Teller strength above excitation energies of 3 MeV is more fragmented than predicted by the shell-model calculation.

Beta-decay half-lives and β-delayed neutron-emission probabilities of the very neutron-rich nuclei 43 P, 42,44,45 S and 44–46 Cl, 47 Ar, which lie at or close to the N=28 magic shell, have been recently measured through β or β-n time correlation measurement. The results are compared to recent model predictions and indicate a rapid weakening of the N=28 shell effect below 48 Ca. The nuclear structure effects reflected in the decay properties of the exotic S and Cl isotopes may be the clue for the astrophysical understanding of the unusual 48 Ca 46 Ca abundance ratio measured in the solar system.

Using a 112 Sn beam delivered by the GANIL cyclotrons in conjunction with the high acceptance device SISSI, proton-rich nuclei in the region of A=100 have been produced and subsequently analysed by the LISE3 spectrometer. As a result the doubly magic nucleus 100 Sn was identified with 11 events recorded during 44 hours.

Reactions of a 41 MeV/u beam of the radioactive halo nucleus Be-11 have been studied with a counter telescope coupled to an array of neutron detectors covering angles up to 97-degrees. The technique allows to determine single-neutron inclusive and exclusive angular distributions. The targets (Be, Ti and Au) were chosen to illustrate the relative roles played by nuclear and Coulomb mechanisms. The channels leading to Be-10, the dissociation channels, correspond to impact parameters larger than the sum of the radii of the target and the Be-10 core. It is shown that for the dissociation process it is possible to account almost quantitatively for the integral, single- and double-differential cross sections from models without free parameters including the Coulomb, Serber and Glauber (diffraction-dissociation) mechanisms. The neutron distributions from the nondissociative reaction channels show little individuality and it is convenient to group them together as the channel ''neutron plus anything different from Be-10''. We refer to these as ''restricted-inclusive'' reactions. These seem to be a promising tool for obtaining accurate information on the halo wave function in momentum coordinates.

A 42 Sc m isomeric beam was produced for the first time at GANIL. The 12 C( 40 Ca, 42 Sc m ) 10 B transfer reaction at 30 MeV / A yielded an isomeric purity of 98±5%. Using the LISE3 on line separation, 30% of the residual 40 Ca nuclei were observed. A 42 Sc m secondary beam intensity of 114 pps was obtained with a 3 10 10 pps 40 Ca incident beam bombarding the 5 mg/cm 2 12 C target.

A new method is presented for the thermomechanical analysis of composite microstructures. The problem is defined on a unit cell of arbitrary geometry with the displacement field written in two parts: a slowly varying macroscopic part and a microscopic part for which periodic boundary conditions are imposed. The macroscopic stress field is then found by averaging the stress obtained from a finite element solution of the microscopic displacement field as a function of the macroscopic strains. Two- and three-dimensional microscopic analyses have been conducted for two different metal-matrix composites: unidirectional continuous boron fibers in an aluminum matrix and silicon carbide particles in an aluminum matrix. Theoretical elastic and yielding results are presented and compared with experimental tension, compression, and pure shear tests. The effects of the choice of microscopic geometry, reinforcement loading, finite element resolution, residual stresses and initial hardening are demonstrated.

The elastic scattering of a secondary 11 Li beam (29 MeV/nucleon) on a 28 Si target has been measured for the first time. To compensate for the low intensity of the secondary beam, an efficient detecting system permitting one to obtain reliable experimental data has been used. An attempt has been made to reproduce the data in a phenomenological analysis and with coupled-channel calculations with a double-folding optical potential, with energy- and density-dependent effective interaction and realistic densities. In coupled-channel calculations with the folding optical potential a better description is achieved if a neutron halo of 11 Li is taken into account.

Beta-decay half-lives and \ensuremath{\beta}-delayed neutron-emission probabilities of the very neutron-rich nuclei $^{44}\mathrm{S}$ and $^{45--47}\mathrm{Cl}$ have been measured. These isotopes, which lie at or close to the N=28 magic shell, were produced in interactions of a 60 MeV/u $^{48}\mathrm{Ca}$ beam from GANIL (Grand Acc\'el\'erateur National d'Ions Lourds) with a $^{64}\mathrm{Ni}$ target, and were separated by the doubly achromatic spectrometer LISE (Ligne d'Ions Super Epluch\'es). Their decay was studied by a \ensuremath{\beta}-n time correlation measurement. The results are compared to recent model predictions and indicate a rapid weakening of the N=28 shell effect below $_{20}^{48}\mathrm{Ca}_{28}$. The nuclear structure effects reflected in the decay properties of the exotic S and Cl isotopes may be the clue for the astrophysical understanding of the unusual $^{48}\mathrm{Ca}$${/}^{46}$Ca abundance ratio measured in the solar system as well as the Ca-Ti-Cr anomalies observed in E. King inclusions of the Allende meteorite.

The different {beta}-delayed particle-decay modes of {sup 31}Ar are investigated by means of a new silicon-detector telescope. Identification of {beta}-delayed two-proton decay, and {beta}-delayed three-proton decay observed for the first time, is made possible by Monte Carlo simulations of the detector response. Other {beta}-delayed single-proton branches are also investigated, and none of the energetically allowed {beta}-{alpha} and {beta}-{ital p}{alpha} decay modes are found. Finally, the results of this experiment are compared to shell-model calculations.

The measurement of the energy spectrum of {sup 14}C nuclei emitted in the spontaneous radioactivity of {sup 223}Ra and {sup 224}Ra has been carried out, using thin and intense sources (480 MBq for {sup 223}Ra and 3550 MBq for {sup 224}Ra). The sources were obtained by implanting mass-separated beams into Al and vitreous C catchers. The measurement was performed with a superconducting solenoidal spectrometer. Our discovery, previously reported, of fine structure in the energy spectrum of {sup 14}C emission from {sup 223}Ra, which is analogous to the one known for {alpha} emission, is confirmed. Only 13% of the branching ratio in {sup 14}C decay leads to the ground state of the residual nucleus, while 81% to the first excited state. For {sup 14}C emission from {sup 224}Ra, a lower limit of 2 for the hindrance factor has been measured for the transition to the first excited state in the residual nucleus. Also, a precise identification in {ital Z} with an {ital E}{times}{Delta}{ital E} telescope has been performed for the radiation from the {sup 223}Ra source. Our measurements of fine structure in {sup 14}C emissions open this field to nuclear structure studies.

An E/A=65 MeV $^{78}\mathrm{Kr}$ beam has been used to produce six new isotopes near the proton-drip line. The newly commissioned A1200 beam-analysis device was used to observe the astrophysically interesting isotope $^{65}\mathrm{As}$, as well as $^{61}\mathrm{Ga}$, $^{62}\mathrm{Ge}$, $^{63}\mathrm{Ge}$, $^{69}\mathrm{Br}$, and $^{75}\mathrm{Sr}$. Implications of the observation of these nuclei are discussed in terms of the astrophysical rp process.

An alignment of the nuclear spin has been observed for a secondary radioactive beam of $^{14}\mathrm{B}$ produced in the fragmentation of a 60 MeV/nucleon $^{18}\mathrm{O}$ beam impinging onto a $^{9}\mathrm{Be}$ target. The fragments were separated and analyzed in momentum by means of the doubly achromatic spectrometer LISE. The spin alignment was determined through a measurement of the anisotropy of the \ensuremath{\beta}-delayed \ensuremath{\gamma}-ray emission. The alignment is found to be small in the momentum region corresponding to the peak of the fragmentation yield, whereas it takes a large negative value for the high-momentum tail. This result is discussed in terms of a simple model of projectile fragmentation. The relevance of this result for the determination of nuclear moments far from stability is considered.

The ALTO facility (Accelerateur Lineaire aupres du Tandem d’Orsay) has been built and is now under commissioning. The facility is intended for the production of low energy neutron-rich ion-beams by ISOL technique. This will open new perspectives in the study of nuclei very far from the valley of stability. Neutron-rich nuclei are produced by photofission in a thick uranium carbide target (UC x ) using a 10 μA, 50 MeV electron beam. The target is the same as that already had been used on the previous deuteron based fission ISOL setup (PARRNE [ F. Clapier et al., Phys. Rev. ST-AB (1998) 013501. ]). The intended nominal fission rate is about 10 11 fissions/s. We have studied the adequacy of a thick carbide uranium target to produce neutron-rich nuclei by photofission by means of Monte-Carlo simulations. We present the production rates in the target and after extraction and mass separation steps. The results from Monte-Carlo simulations are compared to experimental data either with the ALTO facility (in the first step of commissioning, i.e. 100 nA of the electron beam current intensity), or with fast-neutron-induced fission generated from a 26 MeV deuteron beam. The results obtained support the suitability of FLUKA simulation code used to describe all the photofission process with an electron beam energy of 50 MeV.

An attempt has been made to synthesize the extremely neutron-rich isotope $^{26}\mathrm{O}$ in the nuclear reaction 44 MeV/nucleon $^{48}\mathrm{Ca}$+n/rTa. Use was made of magnetic separation and identification methods including time-of-flight and \ensuremath{\Delta}E,E measurements. The $^{26}\mathrm{O}$ nucleus appears to be unstable against particle emission since no events attributable to the $^{26}\mathrm{O}$ nucleus were observed at a level one order of magnitude lower than that predicted from the extrapolated yields. The previously unobserved isotope $^{32}\mathrm{Ne}$ was found to be particle stable and the isotope $^{31}\mathrm{Ne}$ particle unstable. Neutron-separation energies calculated with different models are tabulated.

The \ensuremath{\beta} decay of the neutron-rich ${}_{30}^{81}{\mathrm{Zn}}_{51}$ has been investigated at the PARRNe mass separator at the IPN Orsay. The sources of $^{81}\mathrm{Zn}$ were produced using the ISOL (Isotopic Separation On Line) technique by the fission of ${}^{\mathrm{nat}}$U exposed to the neutron flux produced by the 26-MeV deuteron beam delivered by the MP-Tandem. With \ensuremath{\gamma} and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence measurements, excited levels were attributed to ${}_{31}^{81}{\mathrm{Ga}}_{50}$ for the first time. A partial decay scheme for $^{81}\mathrm{Zn}$ is proposed. The proposed level scheme is well reproduced by shell model calculations using the most recent effective empirical interaction. We show that the structure of this nucleus is consistent with that of the heavier odd-proton $N=50$ isotones within the assumption of strong proton $Z=28$ and neutron $N=50$ effective shell effects. The observed states can be associated to rather simple and clean configurations of three protons placed in the $1{f}_{5/2}$ and $2{p}_{3/2}$ orbits.

International audience; The ALTO facility at IPN Orsay is based on a linear electron accelerator (50 MeV, 10μA) dedicated to the production of neutron rich radiactive beams by photofission of a thick uranium carbide target paced on an ISOL line. The construction of the facility has ended in december 2005 and the first on-line tests have been carried out in mid-2006. The production of fission fragments after separation have been measured and are similar to the calculated predictions. Previously, using the same ISOL line, neutron rich nuclei in the vincinity of 78Ni have been produced and studied using the deuteron beam available at the Tandem accelerator in Orsay. First results on excited states in $^{83}_{32}Ge_{51}$ and $^{81}_{31}Ge_{50}$ have been obtained and discussed in the frame of the shell model.

International audience; Yields of neutron-rich isotopes produced by the photofission were measured at the ISOL ALTO facility. The identification was achieved by a combined measurement of beta and gamma-rays. Production rates for Xe, Kr, Sn, In and I isotopes are presented here. In parallel, empirical estimations for the yields based on the PARRNe experimental data and the results provided by a very recent FLUKA simulation are presented.

New levels were attributed to $^{81}\_{31}$Ga$\_{50}$ and $^{83}\_{32}$Ge$\_{51}$ which were fed by the $\beta$-decay of their respective mother nuclei $^{81}\_{30}$Zn$\_{51}$ and $^{83}\_{31}$Ga$\_{52}$ produced by fission at the "PARRNe" ISOL set-up installed at the Tandem accelerator of the Institut de Physique Nucl\'eaire, Orsay. We show that the low energy structure of $^{81}\_{31}$Ga$\_{50}$ and $^{83}\_{32}$Ge$\_{51}$ can easily be explained within the natural hypothesis of a strong energy gap at N=50 and a doubly-magic character for $^{78}$Ni., Comment: 2 pages, pdf file, To be published in the Proceedings of "International Symposium on Structure of Exotic Nuclei and Nuclear Forces (SENUF 06)", March 2006, Tokyo, Japan

A novel detector telescope suitable for intermediate mass fragments has been developed. The telescope consists of a CsI scintillator whose light is collected using a PIN diode and is termed a “Siswich”. The novel feature of the device is that the PIN diode is placed on the entrance face of the crystal where it functions not only as light collector but as a solid state silicon detector. The use of the PIN diode as a AE counter and the CsI as an E counter provides a high resolution particle telescope capable of mass rese lution. This telescope also has advantage that only one signal is needed with the two components being separated by time gates (fast for the silicon AE and slow for the CsI E). Test results will be presented.

This document identifies and discusses the proper design strategies that have been followed in order to meet the reliability and availability specifications for a high intensity proton accelerator meant as the spallation neutron driver for an eXperimental Driven System (XADS) for nuclear waste transmutation. The document describes also how these strategies can be applied in the different components of the XADS accelerator design, and how design iterations can lead to reliability improvements. The Failure Mode and Effect Analysis (FMEA) methodology has been used on the suggested design for highlighting the reliability critical areas. Finally, a first rough cost estimation of the XADS accelerator is also provided.

A source of neutron rich ions can be conceived through the photo-fission process. An exploratory study of such a source is realized. A survey of the radiative electron energy loss theory is reported in order to estimate numerically the bremsstrahlung production of thick targets. The resulted bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are presented and compared with previous results. Some quantities as the number of fission events produced in the fissionable source and the energy loss in the converters are also reported as function of the geometry of the combination and the incident electron energy. An attempt of comparison with experimental data shows a quantitative agreement. This study is focussed on initial kinetic energies of the electron beam included in the range 30–60 MeV, suitable for the production of large radiative γ-ray yields able to induce the 238 U fission through the giant dipole resonance. A confrontation with the number of fission events produced in the frame of the fast neutron induced fission method indicates that the photo-fission can be a competitive concept.

High-power accelerators are being studied for several projects based on high-flux neutron sources driven by proton or deuteron beams. Since the front end is the most critical part of such accelerators, it has been decided to build a high-intensity proton injector (IPHI) designed to accelerate a CW 100 mA beam up to 11 MeV. The aim is to validate design codes, test technical choices, demonstrate operational reliability and measure the beam parameters in order to optimize the high-energy part of the accelerator. The design chosen for IPHI (ECR source, RFQ, DTL and diagnostic line) and the construction schedule are presented.

A PARRNe 1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) aimed at the production of neutron-rich radioactive noble gases produced by photofission has been performed at CERN. The LEP Pre-Injector (LPI) has been used to deliver a 50 MeV electron beam. The results obtained show clearly that the use of an electron beam to produce neutron-rich fission fragments for futur RNB facilities is an option that should not be neglected.

10 pages, 2 tables, 13 figures.--PACS nrs.: 21.45.1v, 25.10.1s, 21.10.Gv.--ArXiv pre-print available at: http://arxiv.org/abs/nucl-ex/0111001, A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of intermediate energy (30-50 MeV/nucleon) Li-11, Be-14, and B-15 beams. Some six events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of Be-14, most probably in the channel Be-10+(4)n. The various backgrounds that may mimic such a signal are discussed in detail., This work was funded under the auspices of the IN2P3-CNRS (France) and EPSRC (United Kingdom). Additional support from the ALLIANCE program (Ministère des Affaires Etrangères and British Council) and the Human Capital and Mobility Program of the European Community (Contract No. CHGE-CT94-0056) is also acknowledged.