Abstract
Because gadolinium (Gd) has the highest thermal neutron capture cross section, resulting in an 8 MeV gamma cascade upon capture, it has been proposed for dissolution in water Cherenkov ...detectors to achieve efficient neutron tagging capabilities. Whereas metallic Gd is insoluble in water, several compounds are very easy to dissolve. Gadolinium sulfate, Gd2(SO4)3, has been thoroughly tested and proposed as the best candidate. Accurate measurement of its concentration, free of doubt from impurities in water, is crucial. An atomic absorption spectrophotometer (AAS) is a device that suits this purpose and is widely used to measure the concentration of many elements. In this study, we describe three different approaches to measure Gd sulfate concentrations in water using an AAS: doping samples with potassium and lanthanum, and employing tantalum and tungsten platforms.
A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised
e
±
p
scattering at HERA during the ...period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared,
Q
2
, and in Bjorken
x
. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Diffractive electroproduction of ρ and ϕ mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb
−1
. ...About 10500 ρ and 2000 φ events are analysed in the kinematic range of squared photon virtuality 2.5 ≤
Q
2
≤ 60 GeV
2
, photon-proton centre of mass energy 35 ≤
W
≤ 180 GeV and squared four-momentum transfer to the proton |
t
| ≤ 3 GeV
2
. The total, longitudinal and transverse cross sections are measured as a function of
Q
2
,
W
and |
t
|. The measurements show a transition to a dominantly “hard” behaviour, typical of high gluon densities and small
dipoles, for
Q
2
larger than 10 to 20 GeV
2
. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (
Q
2
+
M
2
V
)/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We describe three adults who had hemorrhagic strokes during the acute phase of bacterial meningitis (BM).We also report the results of a literature review and a review of the charts of 296 adults ...treated at our hospital for acute BM. The diagnosis of hemorrhagic stroke was made based on the results of cerebral computed tomography (CT) for two of 92 patients with BMwho had CT performed and by means of lumbar puncture and a postmortem study in one other case. Two patients died of cerebral bleeding. Although the frequency of hemorrhagic stroke was only 2.1% among adults with acute BM, it is a major determinant of prognosis for such patients.
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BFBNIB, NUK, PNG, UL, UM, UPUK
Used for both proton decay searches and neutrino physics, large water Cherenkov (WC) detectors have been very successful tools in particle physics. They are notable for their large masses and charged ...particle detection capabilities. While current WC detectors reconstruct charged particle tracks over a wide energy range, they cannot efficiently detect neutrons. Gadolinium (Gd) has the largest thermal neutron capture cross section of all stable nuclei and produces an 8 MeV gamma cascade that can be detected with high efficiency. Because of the many new physics opportunities that neutron tagging with a Gd salt dissolved in water would open up, a large-scale R&D program called EGADS was established to demonstrate this technique's feasibility. EGADS features all the components of a WC detector, chiefly a 200-ton stainless steel water tank furnished with 240 photo-detectors, DAQ, and a water system that removes all impurities in water while keeping Gd in solution. In this paper we discuss the milestones towards demonstrating the feasibility of this novel technique, and the features of EGADS in detail.
A search for events containing an isolated electron or muon and missing transverse momentum produced in
e
±
p
collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in ...the period 1994–2007 and correspond to an integrated luminosity of 0.98 fb
−1
. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the
e
+
p
data, at large hadronic transverse momentum
P
T
X
> 25GeV, a total of 23 events are observed compared to a prediction of 14.0 ± 1.9. The total single
W
boson production cross section is measured as 1.06 ± 0.16 (stat.) ± 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 ± 0.19 pb.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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