Is There a Significant Difference Between the Results of the Coulomb Dissociation of 8B and the Direct Capture 7Be(p,g)8B Reaction?

Recent claims of the Seattle group of evidence of "slope difference between CD [Coulomb Dissociation] and direct [capture] results" are based on wrong and selective data. When the RIKEN2 data are included correctly, and previously published Direct Capture (DC) data are also included, we observe only a 1.9 sigma difference in the extracted so called "scale independent slope (b)", considerably smaller than claimed by the Seattle group. The very parameterization used by the Seattle group to extract the so called b-slope parameter has no physical foundation. Considering the physical slope (S' = dS/dE), we observe a 1.0 sigma agreement between slopes (S') measured in CD and DC, refuting the need for new theoretical investigation. The claim that S17(0) values extracted from CD data are approximately 10% lower than DC results, is based on misunderstanding of the CD method. Considering all of the published CD S17(0) results, with adding back an unconfirmed E2 correction of the MSU data, yields very consistent S17(0) results that agree with recent DC measurements of the Seattle and Weizmann groups. The recent correction of the b-slope parameter (0.25 1/MeV) suggested by Esbensen, Bertsch and Snover was applied to the wrong b-slope parameter calculated by the Seattle group. When considering the correct slope of the RIKEN2 data, this correction in fact leads to a very small b-slope parameter (0.14 1/MeV), less than half the central value observed for DC data, refuting the need to correct the RIKEN2 data. In particular it confirms that the E2 contribution in the RIKEN2 data is negligible. The dispersion of measured S17(0) is mostly due to disagreement among individual DC experiments and not due to either experimental or theoretical aspects of CD.Comment: Reference 12 amended with an important communication from Dr. Bertsc

Sm-Nd isotopic systematics of the ancient Gneiss complex, southern Africa

In order to shed some new light on the question of the absolute and relative ages of the Ancient Gneiss Complex and Onverwacht Group, a Sm-Nd whole-rock and mineral isochron study of the AGC was begun. At this point, the whole-rock study of samples from the Bimodal Suite selected from those studied for their geochemical characteristics by Hunter et al., is completed. These results and their implications for the chronologic evolution of the Kaapvaal craton and the sources of these ancient rocks are discussed

New broad 8Be nuclear resonances

Energies, total and partial widths, and reduced width amplitudes of 8Be resonances up to an excitation energy of 26 MeV are extracted from a coupled channel analysis of experimental data. The presence of an extremely broad J^pi = 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+ resonance are discovered. A previously known 22 MeV 2^+ resonance is likely resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22 MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-? resonances to be isospin 0.Comment: 16 pages, LaTe

The 8^8B Neutrino Spectrum

Knowledge of the energy spectrum of $^8$B neutrinos is an important ingredient for interpreting experiments that detect energetic neutrinos from the Sun. The neutrino spectrum deviates from the allowed approximation because of the broad alpha-unstable $^8$Be final state and recoil order corrections to the beta decay. We have measured the total energy of the alpha particles emitted following the beta decay of $^8$B. The measured spectrum is inconsistent with some previous measurements, in particular with a recent experiment of comparable precision. The beta decay strength function for the transition from $^8$B to the accessible excitation energies in $^8$Be is fit to the alpha energy spectrum using the R-matrix approach. Both the positron and neutrino energy spectra, corrected for recoil order effects, are constructed from the strength function. The positron spectrum is in good agreement with a previous direct measurement. The neutrino spectrum disagrees with previous experiments, particularly for neutrino energies above 12 MeV.Comment: 15 pages, 13 figures, 4 tables, submitted to Phys. Rev. C, typos correcte

The Infra‐Red Absorption Spectrum of Diborane

The infra‐red absorption spectrum of diborane has been examined under high resolution from 3.7μ to 30μ with automatic recording grating spectrometers. The rotational fine structure in two bands of each of the three types characteristic of asymmetric top molecules has been measured. All results and observations are consistent with the conclusion that diborane has the bridge structure, and belongs to the same symmetry point group, Vh, as ethylene. The observation and structure of the band with center at 368.7 cm−1 provides spectroscopic evidence that the molecule is non‐planar, and makes more definite the assignment of fundamental frequencies. Data on all bands fit quite well the symmetric top approximation, since accidentally two principal moments of inertia are approximately the same, and calculations yield accurate values for certain rotational constants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70903/2/JCPSA6-18-5-698-1.pd

Sympathetic cooling and squeezing of two co-levitated nanoparticles

Levitated particles are an ideal tool for measuring weak forces and investigating quantum mechanics in macroscopic objects. Arrays of two or more of these particles have been suggested for improving force sensitivity and entangling macropscopic objects. In this article, two charged, silica nanoparticles, that are coupled through their mutual Coulomb repulsion, are trapped in a Paul trap, and the individual masses and charges of both particles are characterised. We demonstrate sympathetic cooling of one nanoparticle coupled via the Coulomb interaction to the second nanoparticle to which feedback cooling is directly applied. We also implement sympathetic squeezing through a similar process showing non-thermal motional states can be transferred by the Coulomb interaction. This work establishes protocols to cool and manipulate arrays of nanoparticles for sensing and minimising the effect of optical heating in future experiments.Comment: 8 pages, 4 figure

Performance and limits of feedback cooling methods for levitated oscillators: a direct comparison

Cooling the centre-of-mass motion is an important tool for levitated optomechanical systems, but it is often not clear which method can practically reach lower temperatures for a particular experiment. We directly compare the parametric and velocity feedback damping methods, which are used extensively for cooling the motion of single trapped particles in a range of traps. By performing experiments on the same particle, and with the same detection system, we demonstrate that velocity damping cools the oscillator to lower temperatures and is more resilient to imperfect experimental conditions. We show that these results are consistent with analytical limits as well as numerical simulations that include experimental noise.Comment: 11 pages, 5 figure

The 13N(d,n)14O Reaction and the Astrophysical 13N(p,g)14O Reaction Rate

$^{13}$N($p,\gamma$)$^{14}$O is one of the key reactions in the hot CNO cycle which occurs at stellar temperatures around $T_9$ $\geq$ 0.1. Up to now, some uncertainties still exist for the direct capture component in this reaction, thus an independent measurement is of importance. In present work, the angular distribution of the $^{13}$N($d,n$)$^{14}$O reaction at $E_{\rm{c.m.}}$ = 8.9 MeV has been measured in inverse kinematics, for the first time. Based on the distorted wave Born approximation (DWBA) analysis, the nuclear asymptotic normalization coefficient (ANC), $C^{^{14}O}_{1,1/2}$, for the ground state of $^{14}$O $\to$ $^{13}$N + $p$ is derived to be $5.42 \pm 0.48$ fm$^{-1/2}$. The $^{13}$N($p,\gamma$)$^{14}$O reaction is analyzed with the R-matrix approach, its astrophysical S-factors and reaction rates at energies of astrophysical relevance are then determined with the ANC. The implications of the present reaction rates on the evolution of novae are then discussed with the reaction network calculations.Comment: 17 pages and 8 figure

An analytical model for the detection of levitated nanoparticles in optomechanics

Interferometric position detection of levitated particles is crucial for the centre-of-mass (CM) motion cooling and manipulation of levitated particles. In combination with balanced detection and feedback cooling, this system has provided picometer scale position sensitivity, zeptonewton force detection, and sub-millikelvin CM temperatures. In this article, we develop an analytical model of this detection system and compare its performance with experimental results allowing us to explain the presence of spurious frequencies in the spectra