Demonstration of photomultiplier tube operation at 29 K

We describe measurements of gain, dark current, and quantum efficiency obtained while cooling a Hamamatsu R5912-02-MOD photomultiplier tube from room temperature to 29 K. We found that the PMT operated normally down to 29 K, with a reduced gain and quantum efficiency at the lowest temperatures. Furthermore, we found that the dark count rate increased as the temperature decreased. We conclude that these PMTs appear to be adequate for the requirements of the CLEAN experiment.Comment: 3 pages, 5 figure

Measurement of scintillation efficiency for nuclear recoils in liquid argon

The scintillation light yield of liquid argon from nuclear recoils relative to electronic recoils has been measured as a function of recoil energy from 10 keVr up to 250 keVr at zero electric field. The scintillation efficiency, defined as the ratio of the nuclear recoil scintillation response to the electronic recoil response, is 0.25±0.01+0.01 (correlated) above 20 keVr. © 2012 American Physical Society

Index of refraction, Rayleigh scattering length, and Sellmeier coefficients in solid and liquid argon and xenon

Large liquid argon detectors have become widely used in low rate experiments, including dark matter and neutrino research. However, the optical properties of liquid argon are not well understood at the large scales relevant for current and near-future detectors.The index of refraction of liquid argon at the scin- tillation wavelength has not been measured, and current Rayleigh scattering length calculations disagree with measurements. Furthermore, the Rayleigh scattering length and index of refraction of solid argon and solid xenon at their scintillation wavelengths have not been previously measured or calculated. We introduce a new calculation using existing data in liquid and solid argon and xenon to extrapolate the optical properties at the scintillation wavelengths using the Sellmeier dispersion relationship.Comment: 11 pages, 4 figure

Triplet lifetime in gaseous argon

MiniCLEAN is a single-phase liquid argon dark matter experiment. During the initial cooling phase, impurities within the cold gas ($<$140 K) were monitored by measuring the scintillation light triplet lifetime, and ultimately a triplet lifetime of 3.480 $\pm$ 0.001 (stat.) $\pm$ 0.064 (sys.) $\mu$s was obtained, indicating ultra-pure argon. This is the longest argon triplet time constant ever reported. The effect of quenching of separate components of the scintillation light is also investigated

The phenotype of floating-harbor syndrome:clinical characterization of 52 individuals with mutations in exon 34 of SRCAP

Background\ud Floating-Harbor syndrome (FHS) is a rare condition characterized by short stature, delays in expressive language, and a distinctive facial appearance. Recently, heterozygous truncating mutations in SRCAP were determined to be disease-causing. With the availability of a DNA based confirmatory test, we set forth to define the clinical features of this syndrome.\ud \ud Methods and results\ud Clinical information on fifty-two individuals with SRCAP mutations was collected using standardized questionnaires. Twenty-four males and twenty-eight females were studied with ages ranging from 2 to 52 years. The facial phenotype and expressive language impairments were defining features within the group. Height measurements were typically between minus two and minus four standard deviations, with occipitofrontal circumferences usually within the average range. Thirty-three of the subjects (63%) had at least one major anomaly requiring medical intervention. We did not observe any specific phenotype-genotype correlations.\ud \ud Conclusions\ud This large cohort of individuals with molecularly confirmed FHS has allowed us to better delineate the clinical features of this rare but classic genetic syndrome, thereby facilitating the development of management protocols.The authors would like to thank the families for their cooperation and permission to publish these findings. SdM would like to thank Barto Otten. Funding was provided by the Government of Canada through Genome Canada, the Canadian Institutes of Health Research (CIHR) and the Ontario Genomics Institute (OGI-049), by Genome Québec and Genome British Columbia, and the Manton Center for Orphan Disease Research at Children’s Hospital Boston. KMB is supported by a Clinical Investigatorship Award from the CIHR Institute of Genetics. AD is supported by NIH grant K23HD073351. BBAdV and HGB were financially supported by the AnEUploidy project (LSHG-CT-2006-37627). This work was selected for study by the FORGE Canada Steering Committee, which consists of K. Boycott (University of Ottawa), J. Friedman (University of British Columbia), J. Michaud (University of Montreal), F. Bernier (University of Calgary), M. Brudno (University of Toronto), B. Fernandez (Memorial University), B. Knoppers (McGill University), M. Samuels (Université de Montréal), and S. Scherer (University of Toronto). We thank the Galliera Genetic Bank - “Telethon Genetic Biobank Network” supported by Italian Telethon grants (project no. GTB07001) for providing us with specimens

Measurement of Scintillation Efficiency for Nuclear Recoils in Liquid Argon

The scintillation light yield of liquid argon from nuclear recoils relative to electronic recoils has been measured as a function of recoil energy from 10 keVr up to 250 keVr at zero electric field. The scintillation efficiency, defined as the ratio of the nuclear recoil scintillation response to the electronic recoil response, is 0.25 ± 0.01 + 0.01 (correlated) above 20 keVr

De novo germline and postzygotic mutations in AKT3, PIK3R2 and PIK3CA cause a spectrum of related megalencephaly syndromes

Megalencephaly-capillary malformation (MCAP) and megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndromes are sporadic overgrowth disorders associated with markedly enlarged brain size and other recognizable features. We performed exome sequencing in 3 families with MCAP or MPPH, and our initial observations were confirmed in exomes from 7 individuals with MCAP and 174 control individuals, as well as in 40 additional subjects with megalencephaly, using a combination of Sanger sequencing, restriction enzyme assays and targeted deep sequencing. We identified de novo germline or postzygotic mutations in three core components of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway. These include 2 mutations in AKT3, 1 recurrent mutation in PIK3R2 in 11 unrelated families with MPPH and 15 mostly postzygotic mutations in PIK3CA in 23 individuals with MCAP and 1 with MPPH. Our data highlight the central role of PI3K-AKT signaling in vascular, limb and brain development and emphasize the power of massively parallel sequencing in a challenging context of phenotypic and genetic heterogeneity combined with postzygotic mosaicism