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A setup for measuring cross-sections of evaporation residues produced in the collision of two heavy ions is described. The system, which detects all reaction products in a narrow angular range around the beam direction, is designed to work best with low-intensity beams ( ⩽ 10 5 ions / s ) and can be highly efficient for reactions studied in inverse kinematic conditions, i.e., heavy-mass beam on lighter-mass targets. The system as presented here has been optimized to study evaporation residues from reactions induced by radioactive ion beams with charges near Z ∼ 50 and energies near 4 MeV/nucleon. Continuous sampling of the beam velocity, energy loss and position allow for the measurement of accurate evaporation residue cross-sections also in situations where the beam contains a mixture nuclides.

The low-lying level structure of the unbound neutron-rich nucleus $^{13}$Be has been investigated via breakup on a carbon target of secondary beams of $^{14,15}$B at 35 MeV/nucleon. The coincident detection of the beam velocity $^{12}$Be fragments and neutrons permitted the invariant mass of the $^{12}$Be+$n$ and $^{12}$Be+$n$+$n$ systems to be reconstructed. In the case of the breakup of $^{15}$B, a very narrow structure at threshold was observed in the $^{12}$Be+$n$ channel. Contrary to earlier stable beam fragmentation studies which identified this as a strongly interacting $s$-wave virtual state in $^{13}$Be, analysis here of the $^{12}$Be+$n$+$n$ events demonstrated that this was an artifact resulting from the sequential-decay of the $^{14}$Be(2$^+$) state. Single-proton removal from $^{14}$B was found to populate a broad low-lying structure some 0.70 MeV above the neutron-decay threshold in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)$\hbar\omega$ shell-model calculations, the low-lying structure is concluded to most probably arise from closely spaced J$^\pi$=1/2$^+$ and 5/2$^+$ resonances (E$_r$=0.40$\pm$0.03 and 0.85$^{+0.15}_{-0.11}$ MeV), whilst the broad higher-lying feature is a second 5/2$^+$ level (E$_r$=2.35$\pm$0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2$^+$ and 1/2$^-$ levels lie relatively close together below 1 MeV., Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical Review C

The (d,p) neutron transfer and (d,d) elastic scattering reactions were measured in inverse kinematics using a radioactive ion beam of 132Sn at 630 MeV. The elastic scattering data were taken in a region where Rutherford scattering dominated the reaction, and nuclear effects account for less than 8% of the cross section. The magnitude of the nuclear effects was found to be independent of the optical potential used, allowing the transfer data to be normalized in a reliable manner. The neutron-transfer reaction populated a previously unmeasured state at 1363 keV, which is most likely the single-particle 3p1/2 state expected above the N=82 shell closure. The data were analyzed using finite range adiabatic wave calculations and the results compared with the previous analysis using the distorted wave Born approximation. Angular distributions for the ground and first excited states are consistent with the previous tentative spin and parity assignments. Spectroscopic factors extracted from the differential cross sections are similar to those found for the one neutron states beyond the benchmark doubly-magic nucleus 208Pb., Comment: 22 pages, 7 figures

Atomic nuclei have a shell structure where nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lie outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn., 19 pages, 5 figures and 4 tables

A measurement of the α(12C, α) 12C reaction has been performed using resonant scattering with a gas target. Beam energies of 46, 52, 56 and 63 MeV were used to populate resonances in the excitation energy range of 11.6–22.9 MeV in 16O. The angular distributions of the elastic scattering were measured at zero degrees, using an array of segmented silicon strip detectors with a minimum range of 0°–30° in the centre-of-mass. The spins of 8 resonances between 14.1 and 18.5 MeV were obtained, confirming spin assignments made using elastic scattering in normal kinematics. An R-matrix analysis of the data was performed which indicates that the present understanding of 16O in this region is good, but not complete.

Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q‐value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2 nature of the ground state of 133Sn, and 2p3/2 for the 3.4 MeV state in 131Sn.

Neutron transfer (d, p) reactions have been measured with neutron‐rich fission fragment beams of 130,132Sn and 134Te populating l = 1 and l = 3 excitations above the N = 82 shell gap. Preliminary results and future prospects are discussed.

Neutron transfer (d,p) reaction studies on the N = 50 isotones, 82Ge and 84Se, and A≈130 nuclei, 130,132Sn and 134Te, have been measured. Direct neutron capture cross sections for 82Ge and 84Se (n,γ) have been calculated and are combined with Hauser‐Feshbach expectations to estimate total (n,γ) cross sections. The A≈130 studies used an early implementation of the ORRUBA array of position‐sensitive silicon strip detectors for reaction proton measurements. Preliminary excitation energy and angular distribution results from the A≈130 measurements are reported.

The 82Ge, 84Se, 132Sn, 130Sn, and 134Te (d,p) reactions have been measured with {approx}4-5-MeV-A rare isotope beams and CD2 targets at the HRIBF at ORNL. Energies and spectroscopic strengths have been measured for excitations in 83Ge and 85Se. Direct neutron capture calculations on 82Ge are presented. Preliminary results for single-neutron excitations in 131Sn, 133Sn, and 135Te are reported.

The $^{12}\mathrm{C}$($^{16}\mathrm{O}$,$^{14}\mathrm{O}$)$^{14}\mathrm{C}$ reaction was studied at a beam energy of 234 MeV. The $^{14}\mathrm{O}$ ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited $^{14}\mathrm{C}$ recoil break-up fragments were measured in coincidence with the $^{14}\mathrm{O}$ ejectile using a double sided silicon strip detector array at backward angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the ${}^{14}{\mathrm{C}}^{*}\ensuremath{\rightarrow}{}^{10}\mathrm{Be}+\ensuremath{\alpha}$ and ${}^{14}{\mathrm{C}}^{*}\ensuremath{\rightarrow}{}^{13}\mathrm{C}+n$ decay channels and the branching ratios and widths of these decays were calculated. Theoretical decay branches were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the spins, parities, and configurations of the states. Neutron emission was found to be favored for the 11.73, 12.96, 14.87, 16.72, and 18.6 MeV states. The 14.87, 18.6, and 21.4 MeV states were found to have a considerable width for $\ensuremath{\alpha}$-decay and are candidates for the three bodied molecular cluster structure of $^{14}\mathrm{C}$.

A search has been made for the $^{6}\mathrm{He}+^{6}\mathrm{He}$ and \ensuremath{\alpha} + $^{8}\mathrm{He}$ decay of the molecular rotational band in $^{12}\mathrm{Be}$ using the $^{10}\mathrm{Be}$($^{14}\mathrm{C}$,$^{12}\mathrm{Be}$${}^{*}$)$^{12}\mathrm{C}$ reaction at 88.5 MeV. Although the \ensuremath{\alpha} + $^{6}\mathrm{He}$ decay of $^{10}\mathrm{Be}$ was observed in the data set there is no evidence for the breakup of $^{12}\mathrm{Be}$. The cross-section upper limits for the $^{10}\mathrm{Be}$($^{14}\mathrm{C}$,$^{6}\mathrm{He}$ $^{6}\mathrm{He}$)$^{12}\mathrm{C}$ and $^{10}\mathrm{Be}$($^{14}\mathrm{C}$,\ensuremath{\alpha} $^{8}\mathrm{He}$)$^{12}\mathrm{C}$ reactions are 50 and 300 nb respectively.

The 10.15 MeV resonance in $^{10}\mathrm{Be}$ has been probed via resonant $^{6}\mathrm{He}+^{4}\mathrm{He}$ elastic scattering. It is demonstrated that it is the ${J}^{\ensuremath{\pi}}={4}^{+}$ member of a rotational band built on the 6.18 MeV ${0}^{+}$ state. A ${\ensuremath{\Gamma}}_{\ensuremath{\alpha}}$ of 0.10--0.13 MeV and ${\ensuremath{\Gamma}}_{\ensuremath{\alpha}}/\ensuremath{\Gamma}=0.35--0.46$ were deduced. The corresponding reduced $\ensuremath{\alpha}$ width, ${\ensuremath{\gamma}}_{\ensuremath{\alpha}}^{2}$, indicates one of the largest $\ensuremath{\alpha}$-cluster spectroscopic factors known. The deformation of the band, including the 7.54 MeV, ${2}^{+}$ member, is large (${\ensuremath{\hbar}}^{2}/2I=200\text{ }\text{ }\mathrm{keV}$). Such a deformation and the significant degree of clusterization signals a well-developed $\ensuremath{\alpha}\ensuremath{\mathbin:}2n\ensuremath{\mathbin:}\ensuremath{\alpha}$ molecular structure.

The 10.15 MeV resonance in 10Be has been probed via resonant 6He+4He elastic scattering. It is demonstrated that it is the Jpi=4+ member of a rotational band built on the 6.18 MeV 0+ state. A Gammaalpha of 0.10-0.13 MeV and Gammaalpha/Gamma=0.35-0.46 were deduced. The corresponding reduced alpha width, gamma2alpha, indicates one of the largest alpha-cluster spectroscopic factors known. The deformation of the band, including the 7.54 MeV, 2+ member, is large (h2/2I=200 keV). Such a deformation and the significant degree of clusterization signals a well-developed alpha:2n:alpha molecular structure.

Evaporation residue cross sections for 132Sn, 134Te and 124Sn with 64Ni were measured. A compact system to measure these cross sections to values as low as 1 mb is described and a sample of data acquired with this system is shown.

The discharge of nickel into aquatic environments from numerous industries poses a threat to fish populations because of its toxcity. Although little is known, however, about the precise mechanism of its toxicity in freshwater fish, it produces some of the symptoms associated with heavy-metal poisoning in general; it accumulates in fish tissues and results in alterations in gill structure, including hypertrophy of respiratory and mucous cells, separation of the epithelial layer from the pillar cell system, cauterization and sloughing, and necrosis of the epithelium. The destruction of the gill lamellae decreases the ventilation rate and if severe, as after acute exposure, may cause blood hypoxia and death. The effects of short-term exposure of fish to sublethal concentrations of nickel and not as well defined. The kinetic method of Ellgaard et al., which uses locomotor activity to assess the general health of fish, is ideally suited to examine whether sublethal concentrations of nickel adversely affect fish. In previous studies, the measured changes in locomotor activity observed when fish are exposed to pollutants correlate with more specific changes, e.g., physiological, biochemical, histological or neurosensory changes, which occur under the same conditions. Thus, the kinetic method also meets the criterial for pollution earlymore » warning systems as discussed by Cairns and van der Schale. This method has previously been used to demonstrate that short-term exposure to sublethal concentrations of the heavy metals cadmium, chromium, and zinc and copper are detrimental to the health of bluegills. The present study examines the effects of short-term exposures of sublethal concentrations of nickel on the locomotor activity of the goldfish, Carassius auratus. 11 refs., 1 fig., 2 tabs.« less

International audience; A search for the 2 + excitation of the Hoyle state in 12 C has been performed using the 12 C(12 C, 3α) 12 C reaction at a beam energy of 101.5 MeV. An angular correlation analysis was used to suppress known contributions to the excitation energy spectrum, enhancing the experimental sensitivity. No strong evidence was found for new states in 12 C between 9 and 11 MeV ; rather upper limits for their excitation in the 12 C+ 12 C inelastic scattering reaction are determined.

The effects of transforming growth factor-beta (TGF-beta) and ACTH on growth, as indicated by [3H]thymidine incorporation into DNA, of primary cultures of neocortical cells from the human fetal adrenal gland were studied. TGF-beta inhibited, in a dose- and time-dependent manner, the growth of fetal neocortical cells, and ACTH significantly blunted the inhibitory effects of TGF-beta on growth of these cells. ACTH did not block the inhibitory effects of TGF-beta on growth of fetal adrenal fibroblasts or liver cells; neither ACTH nor TGF-beta had any effect on growth of fetal kidney cells. Thus, it appears that growth regulation of the neocortex may differ strikingly from that of the fetal zone of the human fetal adrenal, in which ACTH and TGF-beta have been reported recently to have additive inhibitory effects on cell proliferation.

Various excited states in 14C, above the α-decay threshold, are believed to possess a geometric arrangement of three α-particles covalently bound by the two delocalised valence neutrons. The 12C(16O, 14O)14C* reaction was studied at a beam energy of 234 MeV, at the ISL facility at the Hahn-Meitner-Institut (HMI), Berlin. The 14O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited 14C recoil break-up fragments were measured in coincidence using a double sided silicon strip detector array comprised of four detectors at backwards angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the 14C* → 10Be + α and 14C* → 13C + n decay channels and the branching ratios of these decays were calculated. Neutron emission was found to be favoured for the 12.96, 14.87, 16.72 and 18.6 MeV states. Evidence for α-decay was found for the 14.87, 18.6 and 21.4 MeV states; which are candidates for the three bodied molecular cluster structure of 14C.

Liquid measuring procedures used in a 12-month study of the hydrology of the soil treatment system at Campbell Soup Company's Paris, Texas plant accounted for 93% of the total liquid applied to the soil. The rainfall and wastewater applied to the soil system are accounted for as follows: 18% is lost to the atmosphere through evaporative processes; 61% is recovered as runoff; and 21% percolates through the soil. The fraction of the treated wastewater recovered as runoff ranges from a low of 30% to a high of 85%. This range in the percent runoff is influenced by climate, soil textural class, and wastewater spray schedules. Wastewater spray schedules are controlled to partially offset variations in the percent runoff which would normally occur as the result of climatic influences.

A group of multifunctional surfactants was synthesized in order to arrive at materials which might function well in hard water. The salts of alkylaryl sulfopropionates, ; alkylaryl sulfonamides of taurine R-C6H4-SO2NHCH2CH2SO3Na; and the alkylaryl sulfonamide of aminoethylsulfuric acid R-C6H4-SO2NHCH2CH2OSO3Na were found to be quite effective. These compounds were synthesized via conventional routes and their biodegradability was established. These materials were formulated into the detergents with the aid of various organic and inorganic builders other than condensed phosphates. The detergency of these materials was evaluated with the aid of standard test cloths. Analogously formulated detergents based upon linear alkylbenzenesulfonate were also included for comparison in this evaluation study. It was found that a number of fairly satisfactory phosphate-free heavy duty detergent formulations could be developed.

DRAINAGE requirements for land application waste-water treatment are discussed based on the mode of treatment: slow-rate (irrigation), rapid-infiltration, or overland-flow. The pertinent characteristics of each of the treatment modes are introduced and differences in drainage requirements discussed.

Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on {sup 130,132}Sn, {sup 134}Te and {sup 75}As are discussed.