Role of Chiral Two-Body Currents in

A direct measurement of the decay width of the excited 0_{1}^{+} state of ^{6}Li using the relative self-absorption technique is reported. Our value of Γ_{γ,0_{1}^{+}→1_{1}^{+}}=8.17(14)_{stat.}(11)_{syst.} eV provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order.

Publisher Correction: The observation of vibrating pear-shapes in radon nuclei.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Accessing the Single-Particle Structure of the Pygmy Dipole Resonance in

New experimental data on the neutron single-particle character of the Pygmy Dipole Resonance (PDR) in ^{208}Pb are presented. They were obtained from (d,p) and resonant proton scattering experiments performed at the Q3D spectrograph of the Maier-Leibnitz Laboratory in Garching, Germany. The new data are compared to the large suite of complementary, experimental data available for ^{208}Pb and establish (d,p) as an additional, valuable, experimental probe to study the PDR and its collectivity. Besides the single-particle character of the states, different features of the strength distributions are discussed and compared to large-scale shell model (LSSM) and energy-density functional plus quasiparticle-phonon model theoretical approaches to elucidate the microscopic structure of the PDR in ^{208}Pb.

Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive

There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.

The observation of vibrating pear-shapes in radon nuclei.

There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the Standard Model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we observed the low-lying quantum states in 224Rn and 226Rn by accelerating beams of these radioactive nuclei. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.

E2 decay strength of the M1 scissors mode of

The E2/M1 multipole mixing ratio δ_{1→2} of the 1_{sc}^{+}→2_{1}^{+} γ-ray decay in ^{156}Gd and hence the isovector E2 transition rate of the scissors mode of a well-deformed rotational nucleus has been measured for the first time. It has been obtained from the angular distribution of an artificial quasimonochromatic linearly polarized γ-ray beam of energy 3.07(6) MeV scattered inelastically off an isotopically highly enriched ^{156}Gd target. The data yield first direct support for the deformation dependence of effective proton and neutron quadrupole boson charges in the framework of algebraic nuclear models. First evidence for a low-lying J^{π}=2^{+} member of the rotational band of states on top of the 1^{+} band head is obtained, too, indicating a significant signature splitting in the K=1 scissors mode rotational band.

Direct Evidence of Octupole Deformation in Neutron-Rich

The neutron-rich nucleus ^{144}Ba (t_{1/2}=11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV ^{144}Ba beam on a 1.0-mg/cm^{2} ^{208}Pb target. The measured value of the matrix element, ⟨3_{1}^{-}∥M(E3)∥0_{1}^{+}⟩=0.65(+17/-23) eb^{3/2}, corresponds to a reduced B(E3) transition probability of 48(+25/-34) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.

Investigating the Pygmy Dipole Resonance Using ß Decay.

In this contribution it is explored whether γ-ray spectroscopy following ß decay with high Q values from mother nuclei with low ground-state spin can be exploited as a probe for the pygmy dipole resonance. The suitability of this approach is demonstrated by a comparison between data from photon scattering, ^{136}Xe(γ,γ^{'}), and ^{136}I [J_{0}^{π}=(1^{-})]→^{136}Xe^{*} ß-decay data. It is demonstrated that ß decay populates 1^{-} levels associated with the pygmy dipole resonance, but only a fraction of those. The complementary insight into the wave functions probed by ß decay is elucidated by calculations within the quasiparticle phonon model. It is demonstrated that ß decay dominantly populates complex configurations, which are only weakly excited in inelastic scattering experiments.

(97)(37)Rb(60): The Cornerstone of the Region of Deformation around A ∼ 100 [corrected].

Excited states of the neutron-rich nuclei (97,99)Rb were populated for the first time using the multistep Coulomb excitation of radioactive beams. Comparisons of the results with particle-rotor model calculations provide clear identification for the ground-state rotational band of (97)Rb as being built on the πg(9/2) [431] 3/2(+) Nilsson-model configuration. The ground-state excitation spectra of the Rb isotopes show a marked distinction between single-particle-like structures below N=60 and rotational bands above. The present study defines the limits of the deformed region around A∼100 and indicates that the deformation of (97)Rb is essentially the same as that observed well inside the deformed region. It further highlights the power of the Coulomb-excitation technique for obtaining spectroscopic information far from stability. The (99)Rb case demonstrates the challenges of studies with very short-lived postaccelerated radioactive beams.

Constraint on 0νßß matrix elements from a novel decay channel of the scissors mode: the case of 154Gd.

The nucleus (154)Gd is located in a region of the nuclear chart where rapid changes of nuclear deformation occur as a function of particle number. It was investigated using a combination of γ-ray scattering experiments and a γγ-coincidence study following electron capture decay of (154)Tb(m). A novel decay channel from the scissors mode to the first excited 0(+) state was observed. Its transition strength was determined to B(M1;1(sc)(+)→0(2)(+))=0.031(4)µ(N)(2). The properties of the scissors mode of (154)Gd imply a much larger matrix element than previously thought for the neutrinoless double-ß decay to the 0(2)(+) state in such a shape-transitional region. Theory indicates an even larger effect for (150)Nd.

Studies of pear-shaped nuclei using accelerated radioactive beams.

There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are 'octupole deformed', that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on (220)Rn and (224)Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model.

Isospin character of the pygmy dipole resonance in 124Sn.

The pygmy dipole resonance has been studied in the proton-magic nucleus 124Sn with the (α, α'γ) coincidence method at Eα=136 MeV. The comparison with results of photon-scattering experiments reveals a splitting into two components with different structure: one group of states which is excited in (α, α'γ) as well as in (γ, γ') reactions and a group of states at higher energies which is only excited in (γ, γ') reactions. Calculations with the self-consistent relativistic quasiparticle time-blocking approximation and the quasiparticle phonon model are in qualitative agreement with the experimental results and predict a low-lying isoscalar component dominated by neutron-skin oscillations and a higher-lying more isovector component on the tail of the giant dipole resonance.

Decay of 1+ states as a new probe of the structure of 0+ shape isomers.

The nuclides 98Mo and 100Mo have been studied in photon-scattering experiments by using bremsstrahlung produced from electron beams with kinetic energies from 3.2 to 3.8 MeV. Six electromagnetic dipole transitions in 98Mo and 19 in 100Mo were observed for the first time in the energy range from 2 to 4 MeV. A specific feature in the two nuclides is the de-excitation of one state with spin J = 1 to the 0+ ground state as well as to the first excited 0+ state, which cannot be explained in standard models. We present a model that allows us to deduce the mixing coefficients for the two 0+ shape-isomeric states from the experimental ratio of the transition strengths from the J = 1 state to the 0+ ground state and to the 0+ excited state.

Brief psychological intervention with traumatized young women: the efficacy of eye movement desensitization and reprocessing.

To study the efficacy of eye movement desensitization and reprocessing (EMDR) with traumatized young women, 60 women between the ages of 16 and 25 were randomly assigned to two sessions of either EMDR or an active listening (AL) control. Factorial ANOVA interaction effects and simple main effects for outcome measure (Beck Depression Inventory, State-Trait Anxiety Inventory, Penn Inventory for Posttraumatic Stress Disorder, Impact of Event Scale, Tennessee Self-Concept Scale) indicated significant improvement for both groups and significantly greater pre-post change for EMDR-treated participants. Pre-post effect sizes for the EMDR group averaged 1.56 compared to 0.65 for the AL group. Despite treatment brevity, the posttreatment outcome variable means of EMDR-treated participants compared favorably with nonpatient or successfully treated norm groups on all measures.

Collagen, proteoglycan and hyaluronidase activity in cultures from normal and scoliotic chicken fibroblasts.

Connective tissue matrix components were investigated using skin fibroblasts from normal or inbred scoliotic lines of chickens. Specifically, the fibroblasts were obtained from either an isogenic line or a backcross, derived by crossing the isogenic line with a pure line of scoliotic birds. From the backcross, both affected (35-45%) and non-affected (55-65%) progeny were produced. The affected birds had spinal curves greater than 20 degrees. Several abnormalities of connective tissue were observed when cells from scoliotic chicks were grown in culture: increased collagen extractability, decreased aggregatability of proteoglycans under associative conditions and lower than normal levels of hyaluronic acid. There was also less collagen deposited in the cell layer with proportionately increased amounts of collagen secreted into the culture media by cells from scoliotic versus normal chick fibroblasts. Values for collagen matrix stability, as estimated by extractability and net deposition, were intermediate for cells from the backcrossed, but non-affected, birds. Moreover, hyaluronidase, an enzyme that degrades hyaluronic acid, was abnormally elevated in the fibroblast cultures from scoliotic chicks. It is proposed that the increase in hyaluronidase contributes to the abnormalities observed in extracellular matrix components and may be a factor in the expression of scoliosis in susceptible birds.

Pedicle fat grafts for the prevention of scar in low-back surgery. A preliminary report on the first 92 cases.

Encouraged by the results of an experimental study on dogs, the authors performed pedicle fat grafts in 92 patients. The grafts were used in the following groups of patients: following primary disc removal (37 cases); following scar removal in the multiply operated back with definite root findings (37 cases); in patients with spondylolisthesis who had had prior decompressions but developed fifth lumbar nerve root pain after lateral fusion (6 cases); in three patients with spondylolisthesis and simple decompression; in nine patients with spinal stenosis. Pedicle fat grafts were obtained from the subcutaneous layer of fat of the low back in 85 patients and from the buttocks in seven patients. The grafts were brought through openings in the fascia and muscle and were used to cover the dural sac as well as the margins of the nerve root. They were held in position by a fine suture of silk. The results after a minimum follow-up of 1 year and a maximum of 4 years have been excellent or good in 66 percent of the patients who have had lateral fusion with resultant L5 root compression, in 99 percent of patients with spondylolisthesis and decompression only, and in 66 percent of patients with spinal stenosis. The results in the other two groups compare favorably with those reported in the literature.

Brachial neuritis.

Brachial neuritis is an unusual syndrome of unknown etiology that can be confused with other causes of pain or weakness, or both, of the shoulder and arm. It is important to distinguish this disorder because of its dramatic symptoms and relatively good prognosis. Sharp pain, usually in the elbow or shoulder, marks the onset of brachial neuritis, but is relatively short-lived. Weakness generally occurs as the pain is subsiding and most frequently involves the deltoid, spinati, serratus anterior, biceps, and triceps. Paresthesias, atrophy, and sensory loss are inconstant features. Electromyographic findings of fibrillation potentials and positive waves characteristically are found in a pattern indicating combined nerve-root and peripheral nerve involvement. Electromyography more frequently than clinical examination shows that the lesion is bilateral, and also is of both diagnostic and prognostic value. Other laboratory studies serve only to exclude other causes of shoulder pain. The clinical course is variable, but in 90 per cent of patients complete recovery occurs within three years. Recurrences are uncommon.

Surgical treatment of nonunions of the surgical neck of the humerus.

End-to-end alignment of the fragments usually does not provide good bone contact or stability for fractures of the surgical neck of the humerus because cavitation of the head fragment and comminution constitute bone stock deficiency. Painful and disabling nonunion of the surgical neck of the humerus in five patients was repaired by impaling one fragment into the other, usually the shaft into the head. A corticocancellous iliac graft bridged the nonunion by extending from the interior of the head to the shaft, where it was fixed by screws. Rush rods were used for internal fixation. All five patients obtained union without evidence of avascular necrosis during the period of observation (12 to 39 months), had good pain relief, and regained satisfactory function.