Search

The elastic scattering in the reaction $$^{7}$$ 7 Li+$$^{208}$$ 208 Pb was investigated in the bombarding energy range from 25 to 39 MeV. The real and imaginary parts of the optical potential were analyzed by using a phenomenological potential. A dispersion relation analysis is presented in order to investigate the threshold anomaly effect. It is concluded that $$^{7}$$ 7 Li has an intermediate behavior between the tightly bound nuclei such as $$^{16}$$ 16 O and the loosely bound nuclei such as $$^{6}$$ 6 Li where the lack of the threshold anomaly is unambiguously observed. Reaction cross sections are also extracted from the elastic scattering data and its comparison with the ones of other systems has been performed to draw hints on the effect of the breakup channel.

We introduce the LUNA neutron detector array developed for the investigation of the 13C( α , n )16O reaction towards its astrophysical s -process Gamow peak in the low-background environment of the Laboratori Nazionali del Gran Sasso (LNGS). Eighteen 3He counters are arranged in two different configurations (in a vertical and a horizontal orientation) to optimize neutron detection efficiency, target handling and target cooling over the investigated energy range E α , lab = 300 − 400 keV (E n = 2 . 2 − 2 . 6 MeV in emitted neutron energy). As a result of the deep underground location, the passive shielding of the setup and active background suppression using pulse shape discrimination, we reached a total background rate of 1 . 23 ± 0 . 12 counts/hour. This resulted in an improvement of two orders of magnitude over the state of the art allowing a direct measurement of the 13C( α , n )16O cross-section down to E α , lab = 300 keV. The absolute neutron detection efficiency of the setup was determined using the 51V(p,n)51Cr reaction and an AmBe radioactive source, and completed with a Geant4 simulation. We determined a (34 ± 3)% and (38 ± 3)% detection efficiency for the vertical and horizontal configurations, respectively, for E n = 2 . 4 MeV neutrons.

Gamma-Beams at the HIgS facility in the USA and anticipated at the ELI-NP facility, now constructed in Romania, present unique new opportunities to advance research in nuclear astrophysics; not the least of which is resolving open questions in oxygen formation during stellar helium burning via a precise measurement of the 12C(a,g) reaction. Time projection chamber (TPC) detectors operating with low pressure gas (as an active target) are ideally suited for such studies. We review the progress of the current research program and plans for the future at the HI{\gamma}S facility with the optical readout TPC (O-TPC) and the development of an electronic readout TPC for the ELI-NP facility (ELITPC)., Comment: Contribution Symposium on Radiation Measurements and Applications (SORMA XVII), June 11 - June 14 , 2018, University of Michigan, Ann Arbor

We developed a Monte-Carlo code for describing the reaction kinematics of the two-body direct processes employed of the EXOTIC beam-line of the Laboratori Nazionali di Legnaro (LNL) for the production of light weakly bound radioactive ion beams at energies of a few MeV/u. The program calculates the phase-space distribution of both primary and secondary beams at the target exit and uses these quantities to optimize the secondary beam selection with the EXOTIC spectrometer. The calculations have been performed and compared with the available experimental data for two reactions: (1)H(2)((17)O, (17)F)n and (3)He((6)Li, (8)B)n. (c) 2008 Elsevier B.V. All rights reserved.

The β-decay of 102Sn was studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). A decay scheme has been constructed based on the γ-γ coincidence data. The total experimental Gamow-Teller strength B GT exp of 102Sn was deduced from the TAS data to be 4.2(9). A search for β-delayed γ-rays of 100Sn decay remained unsuccessful. However, a Gamow-Teller hindrance factor h=2:2(3), and a cross-section of about 3 nb for the production of 100Sn in fusion-evaporation reaction between 58Ni beam and 50Cr target have been estimated from the data on heavier tin isotopes. The estimated hindrance factor is similar to the values derived for lower shell nuclei.

The α-decays of 110Xe and 106Te were studied at the GSI on-line mass separator. By using the grow-in and decay of the α activity, observed in pulsed-beam measurement, the half-life of 110Xe was found to be T1/2 = 105+35-25ms. The lifetime of 106Te was determined to be T1/2 = 70+20-10μs by measuring the time between two successive 110Xe →{106} Te →{102} Sn α-decays. The newly determined half-lives were used to calculate reduced α-decay widths for 106Te and 110Xe. Universal systematics of reduced α widths are proposed to search for the evidence of enhancement of the α formation amplitude in the emitters above 100Sn.

Beta decays of 94,96Ag and 103Sn nuclei into proton channels have been studied in the recent experiments at the GSI-ISOL facility. New efficient and chemically selective ion sources provided the highest yields of light silver and tin isotopes. Large arrays of germanium γ-ray and silicon charged-particle detectors, as well as a total absorption spectrometer (TAS) were used to measure β-proton, proton-γ, β-proton-γ and proton-γ-γ spectra. For the decay of 94Ag, we observed high-spin states in 93Rh populated by proton emission following β decay, whose largest spin value (≥39/2) yields an experimental proof for the existence of a second high-spin isomer in 94Ag with I≥17. Its β-decay energy is at least 16.8 MeV, corresponding to an excitation energy ≥5.5 MeV. For 103Sn, the γ rays measured in coincidence with β-delayed protons allowed us to establish the β-decay properties of this isotope. In particular, a QEC value of 7.5(6) MeV is derived from the intensity ratio of protons that are preceded either by EC or by β+ decays and populate the 2+ state in 102Cd.

The \( N=28\) isotone 60Ge , \( T_{z}=-2\), was produced and selected among the products of the fragmentation reaction of a 78Kr beam at 150 MeV/nucleon and a Be target by means of the A1900 fragment separator at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Its decay was studied for the first time using the optical time projection chamber. The \( \beta\)-decay of 60Ge was found to be dominated by \( \beta\)-delayed proton emission, with a branching of \( \approx 100\)% and half-life \( T_{1/2}=20_{-5}^{+7}\) ms.

An exclusive study of 17 F breakup reactions has been performed at the FRIBs facility of the Laboratori Nazionali del Sud in Catania (Italy). The experiment has been performed with the aim of testing the accuracy of the Coulomb-breakup indirect technique used to infer radiative-capture cross sections at low energies. This technique has been used in the 7 Be ( p , γ)8 B case, but has never been tested. By measuring the breakup of 17F into 16 O + p , and comparing the inferred cross section for 16 O ( p ,γ)17 F to direct precise measurements, the influence of E2 transitions and higher-order effects, that are predicted to be significant in Coulomb-breakup reactions, can be evaluated. The first results and preliminary model comparison are reported.

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.

The discovery of the new isotopes 109Xe and 105Te was enabled by the application of a new experimental method using selective pulse shape storage from silicon detectors with digital signal processing electronics. Essential data processing algorithms were developed, which are able to find unique nuclear decay signatures, such as overlapping alpha decay induced signals. An experiment using this method led to the simultaneous detection of isotopes with dramatically different half lives T1/2(109Xe) = 13(2) ms and T1/2(105Te) = 620(70) ns. The ground state decay energies have been measured to be Eα(109Xe) = 4062(7) keV and Eα(105Te) = 4703(5) keV via observation of correlated events in the decay chain 109Xe → 105Te → 101Sn.

The perspectives for photonuclear experiments at the new Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility are discussed in view of the need to accumulate novel and more precise nuclear data. The parameters of the ELI-NP gamma beam system are presented. The emerging experimental program, which will be realized at ELI-NP, is presented. Examples of day-one experiments with the nuclear resonance fluorescence technique, photonuclear reaction measurements, photofission experiments and studies of nuclear collective excitation modes and competition between various decay channels are discussed. The advantages which ELI-NP provides for all these experiments compared to the existing facilities are discussed.

The $\ensuremath{\beta}$-decay properties of neutron-rich $^{87}\mathrm{As}$ produced in the proton-induced fission of $^{238}\mathrm{U}$ were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The low-energy excited states in $N=53 ^{87}\mathrm{Se}$ and $N=52 ^{86}\mathrm{Se}$ were identified through $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\beta}$-delayed neutron-$\ensuremath{\gamma}$ decay of $^{87}\mathrm{As}$, respectively. The experimental systematics of low-energy levels of $N=53$ isotones, $Z=34 ^{87}\mathrm{Se},$ and $Z=32 ^{85}\mathrm{Ge}$, and along with an analysis of shell-model calculations, allow us to discuss the main features of excited states expected for the next $N=53$ isotone, $^{83}\mathrm{Zn}$.

The $\ensuremath{\beta}$-decay properties of very neutron rich nuclei $^{86}\mathrm{Ge}$ and $^{86}\mathrm{As}$ were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Spectroscopic information on new excited states in $^{86}\mathrm{As}$ and in $^{86}\mathrm{Se}$ was obtained and is interpreted within an advanced shell model approach. These calculations, previously explaining well the structure of $^{84}\mathrm{Ge}$ and $^{85}\mathrm{Ge}$, are not able to reproduce all the experimentally determined features of the measured level schemes of $^{86}\mathrm{As}$ and $^{86}\mathrm{Se}$. The Gamow-Teller decay of $^{86}\mathrm{Ge}$ and $^{86}\mathrm{As}$ is also investigated in a shell-model framework. The fission yield for $^{86}\mathrm{Ge}$ is discussed.

The energy and angular distributions of $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$ ions produced in the $^{7}\mathrm{Be}\phantom{\rule{4pt}{0ex}}+\phantom{\rule{4pt}{0ex}}^{58}\mathrm{Ni}$ reaction at a bombarding energy of 22 MeV have been measured for the first time. The yield of the heavier helium isotope was four to five times more abundant than that of its lighter counterpart, ruling out the possibility that in this energy range the $^{7}\mathrm{Be}$ reaction dynamics is dominated by the exclusive breakup process $^{7}\mathrm{Be}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}{\phantom{\rule{4pt}{0ex}}}^{3}\mathrm{He}\phantom{\rule{4pt}{0ex}}+\phantom{\rule{4pt}{0ex}}^{4}\mathrm{He}$ (${S}_{\ensuremath{\alpha}}=1.586$ MeV). Extensive kinematic and theoretical calculations suggest that the $^{3}\mathrm{He}$ ions mostly originate from the $^{4}\mathrm{He}$-stripping process and the $^{4}\mathrm{He}$ production is mainly triggered by the fusion-evaporation channel. The role played by the breakup, $^{3}\mathrm{He}$-stripping, $1n$-stripping, and $1n$-pickup processes is also discussed.

The rare $\ensuremath{\beta}$-decay channel of $^{6}\mathrm{He}$ into the $\ensuremath{\alpha}+d$ continuum was investigated at the REX-ISOLDE facility. Bunches of postaccelerated $^{6}\mathrm{He}$ ions were implanted into the optical time projection chamber (OTPC), where the decays with emission of charged particles were recorded. This novel technique allowed us to extend the low-energy end of the spectrum down to 150 keV in $\ensuremath{\alpha}+d$ center of mass, corresponding to a deuteron energy of 100 keV. The branching ratio for this process amounts to $[2.78\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.17(\mathrm{sys})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. The shape of the spectrum is found to be in a good agreement with a three-body model, while the total intensity is about 20% larger than the predicted one.

In an experiment at the A1900 spectrometer of the National Superconducting Cyclotron Laboratory at Michigan State University the new isotope $^{59}\mathrm{Ge}$ was identified and the cross section for production of the most neutron-deficient $^{59\ensuremath{-}62}\mathrm{Ge}$ isotopes in the fragmentation of a $^{78}\mathrm{Kr}$ beam at 150 MeV/nucleon measured. This experimental information is relevant for the hunt of new two-proton emitters in the region above the doubly-magic $^{48}\mathrm{Ni}$.

The $\ensuremath{\beta}$ decay of $^{31}\mathrm{Ar}$, produced by fragmentation of an $^{36}\mathrm{Ar}$ beam at 880 MeV/nucleon, was investigated. Identified ions of $^{31}\mathrm{Ar}$ were stopped in a gaseous time projection chamber with optical readout allowing us to record decay events with emission of protons. In addition to $\ensuremath{\beta}$-delayed emission of one and two protons we clearly observed the $\ensuremath{\beta}$-delayed three-proton branch. The branching ratio for this channel in $^{31}\mathrm{Ar}$ is found to be $0.07\ifmmode\pm\else\textpm\fi{}0.02$%.

The β decay of 94Pd and of the 71s isomer of 94Rh was investigated by using total γ-ray absorption techniques. Several levels in 94Rh are established, including a new low-lying isomer characterized by a half-life of 0.48(3)μs and a de-exciting transition of 55keV. E2 multipolarity is determined for this transition by measuring the intensities of its γ-rays and the characteristic X-rays from its electron conversion. On the basis of the measured reduced β-decay transition rates to known 94Ru levels and shell model considerations, the spin-parity of the 71s and the 0.48μs isomers of 94Rh is assigned to be (4+) and (2+), respectively. The β-decay strength distributions measured for 94Pd and the 71s isomer of 94Rh yield Q EC values of 6700(320) and 9750(320)keV for these decays and give evidence for the population of those states below and above the magic N = 50 gap that belong to both components of the 0g spin-orbit doublet.

The β-decay of 105Sn was re-investigated at the ISOL facility of GSI Darmstadt by using a total absorption spectrometer. The experimental results include the half-life and β-delayed proton branching ratio of 32.7(5)s and 1.1(4) . 10-4, respectively, and the contribution of electron capture to the 105Sn decay of 0.420(35). The Gamow-Teller strength distribution peaking at 3.6MeV was measured, yielding a summed Gamow-Teller strength of 3.0(4). The latter data are discussed in comparison with shell-model predictions based on an empirical interaction.

The production cross-sections of proton-rich protactinium and thorium isotopes have been investigated for the fragmentation of 1 A GeV 238 U in a beryllium target at the SIS/FRS facility at GSI Darmstadt. The experimental results are compared with the predictions of an abrasion-ablation model of nuclear fragmentation yielding good overall agreement. Weak evidence for flrst observation of new isotopes 208 Th and 211 Pa is presented.

Properties of nuclei beyond the proton drip line are studied via measurement of the spontaneous emission of protons from these exotic nuclei. Different components of the wave function of the proton emitter can be accessed by observation of fine structure in the proton spectrum. Fine structure has been observed in the proton radioactivity of 145Tm, 146Tm and 141Ho in measurements at the Holifield Radioactive Ion Beam Facility. These nuclei range over an interesting transition region going from nearly spherical to rather deformed. Detailed analysis of the rich fine structure spectrum of 146Tm is presented in terms of the particle-core vibration coupling model. Other models are discussed briefly.

The structure of magic neutron-rich nickel isotopes produced in the fragmentation of a 140 A MeV 86 Kr beam was investigated. For the first time four gamma transitions were assigned to the decay of the I π = 8 + , T 1 / 2 = 590 −110 +180 ns isomer, thus establishing the 0 + – 2 + – 4 + – 6 + – 8 + ground-state band in 76 Ni. The previously unknown 2 + and 4 + levels belonging to the ground-state band in 74 Ni were identified in the β decay of 74 Co ( T 1 / 2 = 30 ( 3 ) ms ) . The decay properties of 72 Co → 72 Ni were verified and confirmed on the basis of γ – γ coincidence data. The relevance of the measured level properties for the magicity of 78 Ni is analyzed with the help of advanced shell-model predictions.

A new way of study the reaction of triple radiative capture αα(n,γ)9Be is demonstrated. At the GSI-ISOL facility, we have measured the γ decays of excited 1/2+, 5/2− and 1/2− states in 9Be, which are strongly populated in the β decay of 9Li. The respective partial γ-widths are of astrophysical interest in order to reliably estimate the αα(n,γ)9Be rates in SN type-II as a possible site of the synthesis of heavy elements in the Universe. The 9Li nuclei were implanted into a foil viewed by high-granularity arrays of β and γ detectors. The γ-ray spectra were measured in coincidence with the β-particles by selecting large β-γ angles in order to suppress the bremsstrahlung background. For the first time, the γ-rays from the 1/2+ and 5/2− states in 9Be were observed in 9Li decay, with the 1/2+-state energy and width measured to be 1689(10) and 224(7) keV, respectively, while the latter transition provided a reference point. The upper limit of the 1/2− partial γ-width is measured to be 7 ⋅ 10 6 MeV . An improved sensitivity experiment is feasible at facilities with the larger yield of 9Li.

Charged-particle decay spectroscopy of heavy suburanium isotopes produced by projectile fragmentation of 1 GeV/u 238 U was tested using a simple implantation–decay set-up equipped with fast-reset preamplifiers. The products were separated and identified with the GSI fragment separator (FRS) and implanted into a stack of Si detectors. Measurements were performed of implantation decay correlations of nuclei with half-lives in the range of 0.1–100 ms. Yields of very neutron-deficient protactinium, thorium and actinium isotopes were measured and yield extrapolations imply that with the availability of a beam intensity of 10 9 ions/s, projectile fragmentation of relativistic 238 U can be an effective method to access new nuclear species including possible proton emitters in the suburanium region.

The very neutron-deficient 117Ba nuclei were produced in 58Ni-induced reactions on a 63Cu target and selected for spectroscopic studies by using BaF+ molecules formed in the ion source of the GSI on-line mass separator. The β-decay of 117Ba was investigated by means of the total absorption γ-ray spectrometer and a telescope for β-delayed particle detection. In the analysis combining the β-delayed γ-ray and proton data the energy window available for β-delayed proton emission, the branching ratios for proton transitions to the 116Xe levels and the β-feeding of the γ-ray and proton-emitting 117Cs states were determined. The β-strength function for 117Ba derived from the measured β-feeding distribution revealed the existence of a broad resonance structure at 117Cs excitation energy of about 4-5 MeV. The results of the β-delayed proton studies and β-strength measurements are confronted with theoretical predictions.

In the present work we report on a new measurement of resonance strengths in the reaction 25Mg(p,gamma)26Al at E_cm= 92 and 189 keV. This study was performed at the LUNA facility in the Gran Sasso underground laboratory using a 4pi BGO summing crystal. For the first time the 92 keV resonance was directly observed and a resonance strength omega-gamma=(2.9+/-0.6)x10E-10 eV was determined. Additionally, the gamma-ray branchings and strength of the 189 keV resonance were studied with a high resolution HPGe detector yielding an omega-gamma value in agreement with the BGO measurement, but 20% larger compared to previous works.

The research programme pursued at the ISOL facility of GSI Darmstadt focuses on the study of decay properties of nuclei along the N≅Z line between the double shell closures at 56Ni and 100Sn. In this report, the major scientific achievements obtained in the past two years are reviewed, with particular emphasis being put on the detection techniques.

We studied the elastic scattering process for the system (17)F + (58)Ni at two colliding energies slightly above the Coulomb barrier. The experimental data were analyzed within the framework of the optical model to investigate the effects of the projectile small binding energy (S(p) = 600 keV) on the reaction dynamics. We found that in this energy range the "reduced" reaction cross section for the system (17)F + (58)Ni is rather similar to that induced by the interaction of tightly-bound (16)O nuclei on the same target. Nuclear Physics A

The dynamical dipole mode, excited in charge asymmetric heavy-ion collisions, was investigated in the mass region of the 192 Pb compound nucleus, formed by using the 40,48 Ca + 152,144 Sm reactions at ∼11 MeV/nucleon. Preliminary results of this measurement, concerning both fusion-evaporation and fission events are presented. As a fast cooling mechanism on the fusion path, the dynamical dipole mode could be useful for the synthesis of super heavy elements through “hot” fusion reactions.

The research programme at the GSI Online Mass Separator focuses on the study of exotic nuclei far from the valley of stability. Special emphasis is placed on the investigation of decay properties of isotopes along the N = Z line between the double shell closures at 56 Ni and 100 Sn. In this contribution, the major recent achievements along with the corresponding experimental methods are reviewed.

Ultra-sensitive in-beam gamma-ray spectroscopy studies for nuclear astrophysics are performed at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator, deep underground in Italy's Gran Sasso laboratory. By virtue of a specially constructed passive shield, the laboratory gamma-ray background for E_\gamma < 3 MeV at LUNA has been reduced to levels comparable to those experienced in dedicated offline underground gamma-counting setups. The gamma-ray background induced by an incident alpha-beam has been studied. The data are used to evaluate the feasibility of sensitive in-beam experiments at LUNA and, by extension, at similar proposed facilities., Comment: accepted, Eur. Phys. J. A

The excited states of odd-odd $^{82}\mathrm{As}$ are studied in the $\ensuremath{\beta}$ decay of $^{82}\mathrm{Ge}$. An isotopically pure beam of $^{83}\mathrm{Ga}$ was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The atoms of $^{82}\mathrm{Ge}$ are created after $\ensuremath{\beta}$-delayed neutron emission in the decay of $^{83}\mathrm{Ga}$. The number of $^{82}\mathrm{Ge}$ atoms is found by normalization to the 1348-keV $\ensuremath{\gamma}$ ray. Detailed analysis of the decay scheme is compared with shell-model calculations with several commonly used $fpg$ shell interactions.

Results of decay spectroscopy on nuclei in the vicinity of the doubly magic $^{48}\mathrm{Ni}$ are presented. The measurements were performed with a time projection chamber with optical readout which records tracks of ions and protons in the gaseous volume. Six decays of $^{48}\mathrm{Ni}$, including four events of two-proton ground-state radioactivity, were recorded. An advanced reconstruction procedure yielded the $2p$ decay energy for $^{48}\mathrm{Ni}$ of ${Q}_{2p}=1.29(4)$ MeV. In addition, the energy spectra of $\ensuremath{\beta}$-delayed protons emitted in the decays of $^{44}\mathrm{Cr}$ and $^{46}\mathrm{Fe}$, as well as half-lives and branching ratios, were determined. The results were found to be consistent with the previous measurements made with Si detectors. A new proton line in the decay of $^{44}\mathrm{Cr}$ corresponding to the decay energy of 760 keV is reported. The first evidence for the $\ensuremath{\beta}2p$ decay of $^{46}\mathrm{Fe}$, based on one clear event, is shown.

We report on a new measurement of $^{14}$N(p,$\gamma$)$^{15}$O for the ground state capture transition at $E_p$ = 360, 380 and 400 keV, using the 400 kV LUNA accelerator. The true coincidence summing effect --the major source of error in the ground state capture determination-- has been significantly reduced by using a Clover--type gamma detector., Comment: 6 pages, 5 figures, Accepted for publication in Journal of Physics G

A new beam line is now fully operational at Laboratori Nazionali di Legnaro (LNL) TANDEM/ALPI accelerator for the in-flight production of light low-energy Radioactive Nuclear Beams (RNBs). The RNBs are produced by inverse kinematics reactions induced by heavy ions, such as 17O and 6Li, on 1H and 3He gas targets. The beam line has a large solid angle acceptance ( Δ Ω = 10 msr ) and a high rejection capability of spurious beams due to the combined action of magnetic rigidity and velocity filtering. A very pure (100%) and high intensity ( 3.6 × 10 6 pps ) 17 F 9 + secondary beam at E lab = 86 ± 1 MeV has been produced and used for experiments. A 8 B 5 + beam at E lab = 33 MeV , with a production rate of ∼ 2 × 10 3 pps , is presently under commissioning.

A new detection apparatus, named EXPADES (EXotic PArticle DEtection System), has been expressly designed to be used in nuclear physics experiments involving exotic beams and devoted to the study of nuclear reactions (scattering, direct reactions, breakup…) at energies around the Coulomb barrier. It consists of double-side segmented silicon detectors arranged in a compact configuration around the target. A very large solid angle, a wide angular range, high granularity and a highly miniaturized readout electronics, based on a new production commercial ASIC chipset, are the main features of the system.

The β decay of the very neutron-deficient isotope 101Sn was studied at the GSI on-line mass separator using silicon detectors for recording charged particles and germanium detectors for γ-ray spectroscopy. Based on the β-delayed proton data the production cross-section of 101Sn in the 50Cr + 58Ni fusion-evaporation reaction was determined to be about 60nb. The half-life of 101Sn was measured to be 1.9(3)s. For the first time β-delayed γ-rays of 101Sn were tentatively identified, yielding weak evidence for a cascade of 352 and 1065keV transitions in 101In. The results for the 101Sn decay as well as those from previous work on the 103Sn decay are discussed by comparing them to predictions obtained from shell model calculations employing a new interaction in the 88Sr to 132Sn model space.

The COMPTEL instrument performed the first mapping of the 1.809 MeV photons in the Galaxy, triggering considerable interest in determing the sources of interstellar 26Al. The predicted 26Al is too low compared to the observation, for a better understanding more accurate rates for the 25Mg(p; gamma)26Al reaction are required. The 25Mg(p;gamma)26Al reaction has been investigated at the resonances at Er= 745; 418; 374; 304 keV at Ruhr-Universitat-Bochum using a Tandem accelerator and a 4piNaI detector. In addition the resonance at Er = 189 keV has been measured deep underground laboratory at Laboratori Nazionali del Gran Sasso, exploiting the strong suppression of cosmic background. This low resonance has been studied with the 400 kV LUNA accelerator and a HPGe detector. The preliminary results of the resonance strengths will be reported., Comment: Accepted for publication in Journal of Physics G

The β decay of 103Sn, a three-neutron-particle nucleus with respect to the 100Sn core, was investigated at the GSI on-line mass separator using an array of 17 germanium crystals and a total absorption spectrometer. A total of 31 β-delayed γ-rays (29 new) of the 103Sn →103 In decay were observed and, on the basis of β-γ-γ coincidences, the 103Sn decay scheme was established for the first time. By means of total absorption spectroscopy, β intensities, the Gamow-Teller strength distribution and the summed Gamow-Teller strength value of 3.5±0.5 were determined for this decay. Its half-life and QEC value were found to be 7.0±0.2 s and 7.64±0.7 MeV, respectively. The β-delayed proton branching ratio was measured to be 1.2±0.1%. The results are discussed in comparison with shell-model predictions based on realistic and empirical interactions.

The β-delayed proton decay of 113Xe was investigated by means of a total absorption γ-ray spectrometer and a telescope for particle detection. The energy window available for the β-delayed proton decay of 113Xe and the relative branching ratios for proton transitions to the 112Te states were remeasured. The lifetimes of proton unstable 113I states populated in the electron capture decay of 113Xe were determined by means of the particle-X-ray coincidence technique. The results of the lifetime measurements are compared with statistical-model calculations.

� SocietItaliana di Fisica / Springer-Verlag 2005 Abstract. The experimental decay properties of the (21 + ) isomer in 94 Ag are briefly discussed.

The β decay of 96Ag (Z=47,N=49) was investigated by measuring positrons, X rays as well as β-delayed protons and γ rays. The γ radiation was studied by means of germanium detectors and a NaI total-absorption spectrometer. Two β-decaying isomers in 96Ag were established with half-lives of 4.40(6) and 6.9(6) s and tentative spin–parity assignments of (8+) and (2+), respectively. For both isomers, the intensities of β transitions to low-lying levels of 96Pd (Z=46,N=50) and β-delayed proton decays to levels in 95Rh (Z=45,N=50) were measured. Several new 96Pd levels were firmly established. The level energies, their γ decays and the Gamow–Teller decay of 96Ag are compared to shell-model predictions. A new low-lying level in 95Rh was found at 680 keV excitation energy. Through a comparison with low-lying states of N=50 isotones, this level is interpreted as the first excited 7/2+ state built on the proton 9/2+ ground state. The assignments of further excited states in 95Rh are discussed.

Evidence for the proton decay of 144Tm was found in an experiment at the Recoil Mass Spectrometer at Oak Ridge National Laboratory. The 144Tm events were found in the weak p5n channel of the fusion reaction using a 58Ni beam at 340 MeV on a 92Mo target. The observed proton decay energies are 1.70 MeV and 1.43 MeV and the half-life ∼ 1.9 µs. The decay properties suggest proton emission from the dominant πh 11/2 part of the wave function and from the small πf 7/2 admixture coupled to a quadrupole vibration.

The evolution of the πh 11/2 vh 11/2 and πh 11/2 vs 1/2 isomeric configurations was studied for the N = 77 isotones near the proton drip line. The decays of metastable levels in 140Eu, 142Tb, and 144Ho were measured by means of X-, gamma- and conversion electron spectroscopy at the Recoil Mass Spectrometer at Oak Ridge. The sequence of isomeric levels in 140Eu was experimentally determined. The half-life of the πh 11/2 vh 11/2 state in 142Tb was remeasured to be 25(1) µs. The spins and parities of 5− and 8+ for the πh 11/2 vs 1/2 and πh 11/2 vh 11/2 142Tb isomers, respectively, were established from measured multipolarities. No evidence for the expected 1+ ground state was found in the 144Ho decay data.

The $\ensuremath{\beta}$-decay properties of neutron-rich ${}^{85}$Ga produced in proton-induced fission of ${}^{238}$U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Data consisted of $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station after high-resolution on-line mass separation. For the first time, the excited states in the $N=53$ isotone ${}^{85}$Ge were established from $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$ decay of ${}^{85}$Ga. The level scheme of the $N=52$ isotone ${}^{84}$Ge was improved and includes now 0${}^{+}$, 2${}^{+}$, (2)${}^{+}$, 4${}^{+}$, and (0)${}^{+}$ states populated in the $\ensuremath{\beta}$-delayed-neutron-$\ensuremath{\gamma}$ decay of ${}^{85}$Ga. Advanced shell-model calculations were used to analyze experimental data on ${}^{85}$Ge and ${}^{84}$Ge.

Short lived neutron rich nuclei including 93 Br, 93 Kr and 94 Kr were produced in proton induced fission of 238 U at the HRIBF in Oak Ridge. Their beta decay was studied by means of a high resolution on line mass separator and beta gamma spectroscopy methods. The half life of 93Br T1/2 = 152(8) ms and delayed branching ratio of Pn = 53-8+11 may be compared to the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half life of 94Kr T1/2 = 227(14) ms and B delayed branching ratio of Pn = 1.9+0.6 0.2 % of 93Kr are in very good agreement with literature values. The decay properties of 93Br include four new gamma transitions following beta delayed neutron emission.

The $\ensuremath{\beta}$-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of ${}^{86}$Ge ($226\ifmmode\pm\else\textpm\fi{}21$ ms) was determined for the first time, while those of ${}^{84,85}$Ge and ${}^{84\ensuremath{-}87}$As were remeasured. The results are compared to theoretical predictions of the gross theory of $\ensuremath{\beta}$ decay, the finite-range droplet model, and the new calculations using the energy density functional DF3a with continuum quasiparticle random-phase approximation (CQRPA). We confirm the robustness and good predictive power of the latter model for nuclei near closed shells. These DF3a+CQRPA calculations were used recently to analyze $r$-process isobaric abundances.