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Purpose: The application of lithium is well known to have an antimanic-depressive effect, however, the influence it has on the human brain is still insufficiently known. The aim of our work is to develop a method to investigate the lithium concentration in the human brain with a very high sensitivity and a submillimeter resolution. Present methods either do not provide spatial resolution or are not sensitive enough to measure the naturally occurring lithium content in the human brain. Our method provides the opportunity to perform postmortem series measurements and obtain a detailed map of the lithium distribution in the human brain. This way possible correlations of the lithium distribution in the human brain and biological reasons for affective disorder can be clarified., Methods: To study the lithium distribution in different regions of the human brain the authors developed a method to measure lithium traces postmortem with a submillimeter spatial resolution using the neutron capture reaction (6)Li(n, α)(3)H. The lithium is measured by coincident detection of the alpha particles and tritons, emitted in opposite directions. The general concept, the preparation of the brain samples, the experimental setup at the measurement station of the Forschungs-Neutronenquelle Heinz Maier-Leibnitz, and a first measurement on human brain tissue are presented., Results: A first measurement on a brain tissue sample nicely showed a spatial distribution of lithium down to a few hundreds of pg∕cm(3) with a maximal resolution of about σ(x) = σ(y) ≈ 200 μm. Also a direct correlation of lithium and optical tissue structure is observable. Typical measurement times of a few minutes allow for series measurements of up to 20 × 20 mm(2) large samples with a thickness of w = 10-20 μm in medical studies., Conclusions: The combination of a very high lithium sensitivity with position resolving measurement makes this method well suited for postmortem studies of the microscopic lithium distribution in the human brain and thus to form a microscopic picture of the impact of lithium in different areas of the human brain.

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During ?+-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of 100Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the ?-decay of 100Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear ?-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, 100In, are well reproduced by modern, large-scale shell model calculations. [ABSTRACT FROM AUTHOR]

By comparing the Q -values for the 46Ti ( 3He , t46V and 47Ti ( 3He , t47V reactions to the isobaric analogue states the Q -value for the superallowed Fermi decay of 46V has been determined as QEC( ^46V ) = (7052.11±0.27) keV. The result is compatible with the values from two recent direct mass measurements but is at variance with the previously most precise reaction Q -value. As additional input quantity we have determined the neutron separation energy Sn( ^47Ti ) = (8880.51±0.25) keV. [ABSTRACT FROM AUTHOR]

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

Lifetimes in 188Pb were measured using the Köln plunger in combination with the RITU separator and JUROGAM. Four lifetimes were measured, from which the deformation of the prolate band was experimentally determined for the first time. The squared prolate mixing amplitude of the 21+ state was deduced from the measured B( E2) values. [ABSTRACT FROM AUTHOR]

Abstract The low energy excited 0 2 , 3 + states in 96Sr are amongst the most prominent examples of shape coexistence across the nuclear landscape. In this work, the neutron [ 2 s 1 / 2 ] 2 content of the 0 1 , 2 , 3 + states in 96Sr was determined by means of the d(95Sr, p) transfer reaction at the TRIUMF-ISAC2 facility using the SHARC and TIGRESS arrays. Spectroscopic factors of 0.19(3) and 0.22(3) were extracted for the 96Sr ground and 1229 keV 0 + states, respectively, by fitting the experimental angular distributions to DWBA reaction model calculations. A detailed analysis of the γ -decay of the isomeric 0 3 + state was used to determine a spectroscopic factor of 0.33(13). The experimental results are compared to shell model calculations, which predict negligible spectroscopic strength for the excited 0 + states in 96Sr. The strengths of the excited 0 2 , 3 + states were also analyzed within a two-level mixing model and are consistent with a mixing strength of a 2 = 0.40 (14) and a difference in intrinsic deformations of | Δ β | = 0.31 (3). These results suggest coexistence of three different configurations in 96Sr and strong shape mixing of the two excited 0 + states. [ABSTRACT FROM AUTHOR]

Abstract: Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable gap in 54Ca. [Copyright &y& Elsevier]

Proton inelastic scattering off a neutron halo nucleus, 11 Li, has been studied in inverse kinematics at the IRIS facility at TRIUMF. The aim was to establish a soft dipole resonance and to obtain its dipole strength. Using a high quality 66 MeV 11 Li beam, a strongly populated excited state in 11 Li was observed at E x = 0.80 ± 0.02 MeV with a width of Γ = 1.15 ± 0.06 MeV . A DWBA (distorted-wave Born approximation) analysis of the measured differential cross section with isoscalar macroscopic form factors leads us to conclude that this observed state is excited in an electric dipole (E1) transition. Under the assumption of isoscalar E1 transitions, the strength is evaluated to be extremely large amounting to 30 ∼ 296 Weisskopf units, exhausting 2.2 % ∼ 21 % of the isoscalar E1 energy-weighted sum rule (EWSR) value. The large observed strength originates from the halo and is consistent with the simple di-neutron model of 11 Li halo. [ABSTRACT FROM AUTHOR]

The quasi-SU(3) sequence of the positive parity νg9/2,d5/2,s1/2 orbitals above the N=40 shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe (Z=26) and Cr (Z=24) isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of 68Ni (Z=28,N=40) through the 66Ni(d,p)67Ni one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball γ-array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-μs isomer at 1007 keV in 67Ni. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the νg9/2 (1007 keV) and νd5/2 (2207 keV and 3277 keV) positive-parity neutron states and negative parity (νpf) states have been observed at low excitation energy. The extracted relative spectroscopic factors, based on a distorted-wave Born approximation analysis, show that the νd5/2 single-particle strength is mostly split over these two excited states. The results are also compared to the distribution of the proton single-particle strength in the 90Zr region (Z=40,N=50). [ABSTRACT FROM AUTHOR]

The ν g 9 / 2 , d 5 / 2 , s 1 / 2 orbitals are assumed to be responsible for the swift onset of collectivity observed in the region below 68 Ni. Especially the single-particle energies and strengths of these orbitals are of importance. We studied such properties in the nearby 67 Ni nucleus, by performing a ( d , p ) -experiment in inverse kinematics employing a post-accelerated radioactive ion beam (RIB) at the REX-ISOLDE facility. The experiment was performed at an energy of 2.95 MeV/u using a combination of the T-REX particle detectors, the Miniball γ -detection array and a newly-developed delayed-correlation technique as to investigate μs-isomers. Angular distributions of the ground state and multiple excited states in 67 Ni were obtained and compared with DWBA cross-section calculations, leading to the identification of positive-parity states with substantial ν g 9 / 2 (1007 keV) and ν d 5 / 2 (2207 keV and 3277 keV) single-particle strengths up to an excitation energy of 5.8 MeV. 50% of the ν d 5 / 2 single-particle strength relative to the ν g 9 / 2 -orbital is concentrated in and shared between the first two observed 5 / 2 + levels. A comparison with extended Shell Model calculations and equivalent ( 3 He,  d ) studies in the region around 90 40 Zr 50 highlights similarities for the strength of the negative-parity pf and positive-parity g 9 / 2 state, but differences are observed for the d 5 / 2 single-particle strength. [ABSTRACT FROM AUTHOR]

The isotopes 122,124,126Cd were studied in a "safe" Coulomb-excitation experiment at the radioactive ion-beam facility REX-ISOLDE at CERN. The reduced transition probabilities B(E2;0+g.s. → 2+1) and limits for the quadrupole moments of the first 2+ excited states in the three isotopes were determined. The onset of collectivity in the vicinity of the Z = 50 and N = 82 shell closures is discussed by comparison with shell model and beyond mean-field calculations. [ABSTRACT FROM AUTHOR]

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

Lifetimes of the low-lying excited states in the very neutron-deficient nucleus 175Au have been measured by the recoil-distance Doppler-shift method using γ-ray spectra obtained with the recoil-decay tagging technique. Transition quadrupole moments and reduced transition probabilities extracted for this odd-Z nucleus indicate the existence of three different shapes and the competition between collective and noncollective structures. [ABSTRACT FROM AUTHOR]

One-neutron knockout data for 18-22N are analyzed in the eikonal approximation of the Glauber model. The role of the s-d shell and the crossing of the N = 14 neutron subshell are discussed. Of particular interest is the nucleus 22N, where the knockout data provide a sensitive experimental test for a possible halo structure of its ground state. The observation of a narrow momentum distribution of the 21N fragments, together with an essential 1s1/2 contribution needed to describe the observed longitudinal-momentum distribution, allow the firm conclusion that the ground state of 22N is a well-developed nuclear halo. The results also show that the N = 14 subshell in 22N is somewhat reduced as compared to that of 23O. [ABSTRACT FROM AUTHOR]

Abstract: One-neutron knockout reactions of 24–28Ne in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, 27Ne and 28Ne, are dominated by a configuration in which a neutron is coupled to an excited state of the 26Ne and 27Ne core, respectively. [Copyright &y& Elsevier]

Abstract: The Munich Accelerator for Fission Fragments (MAFF) facility planned at the research reactor FRM-II in Munich is dedicated to produce, cool and accelerate high-intensity neutron-rich radioactive beams. The radioactive beam of fission fragments results from bombarding a uranium target by the thermal neutrons emerging from the reactor. Part of the nuclides is released from the target/ion source unit in a non-ionized state. This contribution is concerned with simulating the distribution of the non-ionized radioactivity along the MAFF beamline. The calculations are performed with the help of the computer program MOVAK3D. The calculated fraction of non-ionized radioactivity at the border of the experimental area is at the level of about 10−7, relative to the activity produced in the target. [Copyright &y& Elsevier]

At the Munich research reactor FRM-II a radioactive beam facility is planned. About 1014 fissions/s will be induced by thermal neutrons in a target of 235U. Fission products will be ionised, extracted from the neighbourhood of the reactor core, mass analysed and cooled. For some nuclides more than 1011 mass separated ions per second can be obtained. One ion species will be selected in a high-resolution separator and accelerated up to 5.9 MeV/u. [Copyright &y& Elsevier]

In a high-energy fragmentation experiment at GSI an I = π (6 +) isomer and its γ -decay are identified in 102Sn, the two-neutron neighbour of the doubly-magic 100Sn. Its half-life is measured to be T = 1 / 2 367 (11) ns. The possible existence of further isomers is discussed in the framework of large-scale shell model (LSSM) calculations including up to five particle-hole excitations of the 100Sn core. From the precise B(E2; 6 + → 4 +) strength and the recently remeasured value for B(E2; 8 + → 6 +) in the two-proton hole neighbour 98Cd effective E2 polarization charges for protons and neutrons were inferred including LSSM corrections within the full N=4 0 ħ ω space. The results are discussed in comparison to predicted and empirically determined effective operators. [ABSTRACT FROM AUTHOR]

Gamma-ray spectroscopy and lifetime measurements using the Doppler shift attenuation method (DSAM) were performed on the nucleus 28Mg near the N=20 "island of inversion," which was populated using a 12C(18O,2p)28Mg fusion-evaporation reaction to investigate the impact of shell evolution on its high-lying structure. Three new levels were identified at 7203(3), 7747(2), and 7929.3(12) keV along with several new gamma rays. A newly extracted B(E2;4+1→2+1) of 42(7) e²fm4 indicates reduced collectivity in the yrast band at high spin, consistent with ab initio symmetry adapted no-core shell model (SA-NCSM) calculations. At high excitation energy, evidence for the population of intruder orbitals was obtained through identification of negative parity levels [Iπ=(0,4)-, (4,5)-]. Calculations using the SDPF-MU interaction indicate that these levels arise from single neutron excitation to the pf shell and provides evidence for the lowering of these intruder orbitals approaching the island of inversion. [ABSTRACT FROM AUTHOR]

A high precision lifetime measurement of the 21+ state in 94Sr was performed at TRIUMF's ISAC-II facility by coupling the recoil distance method implemented via the TIGRESS integrated plunger with unsafe Coulomb excitation in inverse kinematics. Due to limited statistics imposed by the use of a radioactive 94Sr beam, a likelihood ratio χ² method was derived and used to compare experimental data to Geant4 simulations. The B(E2; 21+ → 01+) value extracted from the lifetime measurement of 7.80-0.4+00.50 (stat.) ± 0.07 (sys.) ps is approximately 25% larger than previously reported while the relative error has been reduced by a factor of approximately 8. A baseline deformation has been established for Sr isotopes with N ≤ 58 which is a necessary condition for the quantum phase transition interpretation of the onset of deformation in this region. A comparison to existing theoretical models is presented. [ABSTRACT FROM AUTHOR]

Abstract: Longitudinal fragment-momentum distributions resulting from one-neutron knockout of 40 different neutron-rich exotic species (Z ranging from 6-13) have been recently measured at high-energy (700 A MeV) using the FRS at GSI. This paper concentrates on results obtained for the Ne isotopic chain where five isotopes (24Ne-28Ne) have been studied. The comparison of those experimental results with simple model calculations shows the evolution of the nuclear structure across neutron numbers N=14,16 in this transitional region in the neighbourhood of the island of inversion. [Copyright &y& Elsevier]