1,816 research outputs found
Anomalous fluctuations of s-wave reduced neutron widths of Pt resonances
We obtained an unprecedentedly large number of s-wave neutron widths through
R-matrix analysis of neutron cross-section measurements on enriched Pt samples.
Careful analysis of these data rejects the validity of the Porter-Thomas
distribution with a statistical significance of at least 99.997%.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let
New resonance parameters for the stable tungsten isotopes from thermal to 1 keV
Neutron resonance parameters of the 182,183,184,186W isotopes were obtained by a resonance shape analysis of experimental data measured at the time-of-flight facility GELINA using the REFIT code. In this document the analysis procedures of capture and transmission data are described. The deduced resonance parameters have been adopted in the new release of the Joint Evaluated Fusion and Fission file, i.e. JEFF-3.2, maintained by the Nuclear Energy Agency of the OECD.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard
Correcting Interdevice Bias of Horizontal White-to-White and Sulcus-to-Sulcus Measures Used for Implantable Collamer Lens Sizing.
PURPOSE: To assess the agreement and repeatability of horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements and use these data in combination with available literature to correct for interdevice bias in preoperative implantable collamer lens (ICL) size selection.
DESIGN: Interinstrument reliability and bias assessment study.
METHODS: A total of 107 eyes from 56 patients assessed for ICL implantation at our institution were included in the study. This was a consecutive series of all patients with suitable available data. The agreement and bias between WTW (measured with the Pentacam and BioGraph devices) and STS (measured with the HiScan device) were estimated.
RESULTS: The mean spherical equivalent was -8.93 ± 5.69 diopters. The BioGraph measures of WTW were wider than those taken with the Pentacam (bias = 0.26 mm, P < .01), and both horizontal WTW measures were wider than the horizontal STS measures (bias >0.91 mm, P < .01). The repeatability (Sr) of STS measured with the HiScan was 0.39 mm, which was significantly reduced (Sr = 0.15 mm) when the average of 2 measures was used. Agreement between the horizontal WTW measures and horizontal STS estimates when bias was accounted for was г = 0.54 with the Pentacam and г = 0.64 with the BioGraph.
CONCLUSIONS: Large interdevice bias was observed for WTW and STS measures. STS measures demonstrated poor repeatability, but the average of repeated measures significantly improved repeatability. In order to conform to the US Food and Drug Administration's accepted guidelines for ICL sizing, clinicians should be aware of and account for the inconsistencies between devices
Clinical Outcomes and Cataract Formation Rates in Eyes 10 Years After Posterior Phakic Lens Implantation for Myopia.
Intraocular collamer lenses (ICLs) are posterior chamber phakic lenses that provide a refractive surgery option for those with high myopia or astigmatism. The short-term and midterm results indicate good refraction stability, efficacy, and safety. Cataract has been suggested to be an important long-term complication of ICL implantation.
To report the rates of cataract development and refractive outcomes 10 years after ICL implantation.
The study included 133 eyes of 78 patients undergoing consecutive V4 model ICL implantations, which took place from January 1, 1998, through December 31, 2004, at Jules-Gonin Eye Hospital, Lausanne, Switzerland. Data analysis was performed from January 1, 2014, to May 31, 2014. The lenses implanted were as follows: 53 V4 model ICLs of -15.5 D or greater, 73 V4 model ICLs of less than -15.5 diopter (D), and 7 V4 model toric ICLs for myopia.
Rate of cataract surgery, lens opacity, ocular hypertension, refractive safety, predictability, and stability.
A total of 133 eyes of 78 patients (34 men and 44 women, with a mean [SD] age of 38.8 [9.2] years at enrollment) met the inclusion criteria. The rate of lens opacity development was 40.9% (95% CI, 32.7%-48.8%) and 54.8% (95% CI, 44.7%-63.0%) at 5 and 10 years, respectively. Phacoemulsification was performed in 5 eyes (4.9%; 95% CI, 1.0%-8.7%) and 18 eyes (18.3%; 95% CI, 10.1%-25.8%) at 5 and 10 years after ICL implantation, respectively. The vault height (distance between the posterior ICL surface and anterior lens surface) measured a mean (SD) of 426 (344) μm immediately postoperatively, decreasing to 213 (169) μm at 10 years. A smaller vault height was associated with the development of lens opacity and phacoemulsification (P = .005 and .008, respectively). The intraocular pressure was 15 mm Hg postoperatively, and there was no significant increase in intraocular pressure observed until the 10-year follow-up (16 mm Hg, P = .02). At 10 years, 12 eyes (12.9%; 95% CI, 5.6%-19.6%) had developed ocular hypertension that required topical medication. At 10 years, the mean (SD) safety index was 1.25 (0.57), with a manifest spherical equivalent of -0.5 D at 1-year postoperatively vs -0.7 D at 10 years postoperatively in eyes aimed at emmetropia.
This retrospective single center study indicates that ICL implantation provides good long-term safety and stability of refraction in patients with high myopia compared with similar short-term studies. However, the rates of cataract formation and ocular hypertension at 10 years have important clinical implications, and as such this information should be part of the available patient information before ICL implantation
Hadron calorimeter with MAPD readout in the NA61/SHINE experiment
The modular hadron calorimeter with micro-pixel avalanche photodiodes readout
for the NA61/SHINE experiment at the CERN SPS is presented. The calorimeter
consists of 44 independent modules with lead-scintillator sandwich structure.
The light from the scintillator tiles is captured by and transported with
WLS-fibers embedded in scintillator grooves. The construction provides a
longitudinal segmentation of the module in 10 sections with independent MAPD
readout. MAPDs with pixel density of /mm ensure good linearity of
calorimeter response in a wide dynamical range. The performance of the
calorimeter prototype in a beam test is reported
CASTOR: Centauro and Strange Object Research in nucleus-nucleus collisions at LHC
We describe the CASTOR detector designed to probe the very forward,
baryon-rich rapidity region in nucleus-nucleus collisions at the LHC. We
present a phenomenological model describing the formation of a QGP fireball in
a high baryochemical potential environment, and its subsequent decay into
baryons and strangelets. The model explains Centauros and the long-penetrating
component and makes predictions for the LHC.
Simulations of Centauro-type events were done. To study the response of the
apparatus to new effects different exotic species (DCC, Centauros, strangelets
etc.) were passed through the deep calorimeter. The energy deposition pattern
in the calorimeter appears to be a new clear signature of the QGP.Comment: Talk given by E. Gladysz-Dziadus for the CASTOR group, Intern.
Workshop on Nuclear Theory, 10-15 June, 2002, Bulgaria, Rila Mountains, 15
pages, 14 figure
Electromagnetic Calorimeter for HADES
We propose to build the Electromagnetic calorimeter for the HADES di-lepton
spectrometer. It will enable to measure the data on neutral meson production
from nucleus-nucleus collisions, which are essential for interpretation of
dilepton data, but are unknown in the energy range of planned experiments (2-10
GeV per nucleon). The calorimeter will improve the electron-hadron separation,
and will be used for detection of photons from strange resonances in elementary
and HI reactions.
Detailed description of the detector layout, the support structure, the
electronic readout and its performance studied via Monte Carlo simulations and
series of dedicated test experiments is presented.
The device will cover the total area of about 8 m^2 at polar angles between
12 and 45 degrees with almost full azimuthal coverage. The photon and electron
energy resolution achieved in test experiments amounts to 5-6%/sqrt(E[GeV])
which is sufficient for the eta meson reconstruction with S/B ratio of 0.4% in
Ni+Ni collisions at 8 AGeV. A purity of the identified leptons after the hadron
rejection, resulting from simulations based on the test measurements, is better
than 80% at momenta above 500 MeV/c, where time-of-flight cannot be used.Comment: 40 pages, 38 figures version2 - the time schedule added, information
about PMTs in Sec.III update
RPC with low-resistive phosphate glass electrodes as a candidate for the CBM TOF
Usage of electrodes made of glass with low bulk resistivity seems to be a
promising way to adapt the Resistive Plate Chambers (RPC) to the high-rate
environment of the upcoming CBM experiment. A pilot four-gap RPC sample with
electrodes made of phosphate glass, which has bulk resistivity in the order of
10^10 Ohm cm, has been studied with MIP beam for TOF applications. The tests
have yielded satisfactory results: the efficiency remains above 95% and the
time resolution stays within 120 ps up to the particle rate of 18 kHz/cm2. The
increase in rate from 2.25 to 18 kHz/cm2 leads to an increase of estimated
"tails" fraction in the time spectrum from 1.5% to 4%.Comment: 8 pages, 6 figures, submitted to Elsevier Scienc
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