Kinematically Complete Measurements of p+p→p+n+(pi+) Near Threshold

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Kinematically Complete Measurements of p+p → p+n+(pi+) Near Threshold

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Kaon-Nucleon Scattering Amplitudes and Z∗^*-Enhancements from Quark Born Diagrams

We derive closed form kaon-nucleon scattering amplitudes using the ``quark Born diagram" formalism, which describes the scattering as a single interaction (here the OGE spin-spin term) followed by quark line rearrangement. The low energy I=0 and I=1 S-wave KN phase shifts are in reasonably good agreement with experiment given conventional quark model parameters. For $k_{lab}> 0.7$ Gev however the I=1 elastic phase shift is larger than predicted by Gaussian wavefunctions, and we suggest possible reasons for this discrepancy. Equivalent low energy KN potentials for S-wave scattering are also derived. Finally we consider OGE forces in the related channels K$\Delta$, K$^*$N and K$^*\Delta$, and determine which have attractive interactions and might therefore exhibit strong threshold enhancements or ``Z$^*$-molecule" meson-baryon bound states. We find that the minimum-spin, minimum-isospin channels and two additional K$^*\Delta$ channels are most conducive to the formation of bound states. Related interesting topics for future experimental and theoretical studies of KN interactions are also discussed.Comment: 34 pages, figures available from the authors, revte

Extreme 54Cr-rich nano-oxides in the CI chondrite Orgueil -Implication for a late supernova injection into the Solar System

Systematic variations in 54Cr/52Cr ratios between meteorite classes (Qin et al., 2010a; Trinquier et al., 2007) point to large scale spatial and/or temporal isotopic heterogeneity in the solar protoplanetary disk. Two explanations for these variations have been proposed, with important implications for the formation of the Solar System: heterogeneous seeding of the disk with dust from a supernova, or energetic-particle irradiation of dust in the disk. The key to differentiating between them is identification of the carrier(s) of the 54Cr anomalies. Here we report the results of our recent NanoSIMS imaging search for the 54Cr-rich carrier in the acid-resistant residue of the CI chondrite Orgueil. A total of 10 regions with extreme 54Cr-excesses ({\delta}54Cr values up to 1500 %) were found. Comparison between SEM, Auger and NanoSIMS analyses showed that these 54Cr-rich regions are associated with one or more sub-micron (typically less than 200 nm) Cr oxide grains, most likely spinels. Because the size of the NanoSIMS primary O- ion beam is larger than the typical grain size on the sample mount, the measured anomalies are lower limits, and we estimate that the actual 54Cr enrichments in three grains are at least 11 times Solar and in one of these may be as high as 50 times Solar. Such compositions strongly favor a Type II supernova origin. The variability in bulk 54Cr/52Cr between meteorite classes argues for a heterogeneous distribution of the 54Cr carrier in the solar protoplanetary disk following a late supernova injection event. Such a scenario is also supported by the O-isotopic distribution and variable abundances in different planetary materials of other presolar oxide and silicate grains from supernovae

Multi-system neurological disease is common in patients with OPA1 mutations

Additional neurological features have recently been described in seven families transmitting pathogenic mutations in OPA1, the most common cause of autosomal dominant optic atrophy. However, the frequency of these syndromal ‘dominant optic atrophy plus’ variants and the extent of neurological involvement have not been established. In this large multi-centre study of 104 patients from 45 independent families, including 60 new cases, we show that extra-ocular neurological complications are common in OPA1 disease, and affect up to 20% of all mutational carriers. Bilateral sensorineural deafness beginning in late childhood and early adulthood was a prominent manifestation, followed by a combination of ataxia, myopathy, peripheral neuropathy and progressive external ophthalmoplegia from the third decade of life onwards. We also identified novel clinical presentations with spastic paraparesis mimicking hereditary spastic paraplegia, and a multiple sclerosis-like illness. In contrast to initial reports, multi-system neurological disease was associated with all mutational subtypes, although there was an increased risk with missense mutations [odds ratio = 3.06, 95% confidence interval = 1.44–6.49; P = 0.0027], and mutations located within the guanosine triphosphate-ase region (odds ratio = 2.29, 95% confidence interval = 1.08–4.82; P = 0.0271). Histochemical and molecular characterization of skeletal muscle biopsies revealed the presence of cytochrome c oxidase-deficient fibres and multiple mitochondrial DNA deletions in the majority of patients harbouring OPA1 mutations, even in those with isolated optic nerve involvement. However, the cytochrome c oxidase-deficient load was over four times higher in the dominant optic atrophy + group compared to the pure optic neuropathy group, implicating a causal role for these secondary mitochondrial DNA defects in disease pathophysiology. Individuals with dominant optic atrophy plus phenotypes also had significantly worse visual outcomes, and careful surveillance is therefore mandatory to optimize the detection and management of neurological disability in a group of patients who already have significant visual impairment

Sedimentation and Fouling of Optical Surfaces at the ANTARES Site

ANTARES is a project leading towards the construction and deployment of a neutrino telescope in the deep Mediterranean Sea. The telescope will use an array of photomultiplier tubes to detect the Cherenkov light emitted by muons resulting from the interaction with matter of high energy neutrinos. In the vicinity of the deployment site the ANTARES collaboration has performed a series of in-situ measurements to study the change in light transmission through glass surfaces during immersions of several months. The average loss of light transmission is estimated to be only ~2% at the equator of a glass sphere one year after deployment. It decreases with increasing zenith angle, and tends to saturate with time. The transmission loss, therefore, is expected to remain small for the several year lifetime of the ANTARES detector whose optical modules are oriented downwards. The measurements were complemented by the analysis of the ^{210}Pb activity profile in sediment cores and the study of biofouling on glass plates. Despite a significant sedimentation rate at the site, in the 0.02 - 0.05 cm.yr^{-1} range, the sediments adhere loosely to the glass surfaces and can be washed off by water currents. Further, fouling by deposits of light-absorbing particulates is only significant for surfaces facing upwards.Comment: 18 pages, 14 figures (pdf), submitted to Astroparticle Physic

The ANTARES Optical Module

The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km-squared and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R & D studies and is reviewed here in detail.Comment: 26 pages, 15 figures, to be published in NI

Search for Gravitational Waves from Intermediate Mass Binary Black Holes

We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100--450 solar masses and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88+88 solar masses, for non-spinning sources, the rate density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.Comment: 13 pages, 4 figures: data for plots and archived public version at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=62326, see also the public announcement at http://www.ligo.org/science/Publication-S5IMBH