159 research outputs found
Neutrino Physics
The author reports inclusive and exclusive searches for neutral currents, the scaling of charged current interactions, and searches for heavy leptons and charmed particles. (23 refs)
The liquid krypton calorimeter cryogenics for the NA48 experiment
The NA48 cryogenic system has to provide stable thermal conditions (120 K) in a 9000 liter liquid krypton calorimeter, and has to ensure safe and loss free storage of the liquid during idle periods. Direct cooling of the krypton by nitrogen is used in emergency cases, while an intermediate cooler, containing saturated liquid argon at around 10 bar (117 K) is used under normal operation conditions when high thermal stability is needed. The krypton pressure is, during data taking, regulated to a value of (1.05 0.01) bar for a period of about 8 months of continuous operation of the calorimeter
An optrode array for spatiotemporally precise large-scale optogenetic stimulation of deep cortical layers in non-human primates
Optogenetics has transformed studies of neural circuit function, but remains challenging to apply in large brains, such as those of non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback projections. To address this unmet need, we have developed the Utah Optrode Array (UOA), a 10×10 glass needle waveguide array fabricated atop a novel opaque optical interposer then bonded to an electrically addressable μLED array. In vivo experiments with the UOA demonstrated large-scale, spatiotemporally precise, activation of deep circuits in monkey cortex. Specifically, the UOA permitted both focal (confined to single layers/columns), and widespread (multiple layers/columns) optogenetic activation of deep layer neurons, simply by varying the number of activated μLEDs and/or the irradiance. Thus, the UOA represents a powerful optoelectronic device for targeted manipulation of deep-layer circuits in NHP models.Competing Interest StatementThe authors have declared no competing interest
Motor Vehicle Crashes in Diabetic Patients with Tight Glycemic Control: A Population-based Case Control Analysis
Using a population-based case control analysis, Donald Redelmeier and colleagues found that tighter glycemic control, as measured by the HbA1c, is associated with an increased risk of a motor vehicle crash
An optrode array for spatiotemporally-precise large-scale optogenetic stimulation of deep cortical layers in non-human primates
Optogenetics has transformed studies of neural circuit function, but remains challenging to apply to non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally-precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback circuits. To address this need, we have developed the Utah Optrode Array (UOA), a 10×10 glass needle waveguide array fabricated atop a novel opaque optical interposer, and bonded to an electrically addressable µLED array. In vivo experiments with the UOA demonstrated large-scale, spatiotemporally precise, activation of deep circuits in NHP cortex. Specifically, the UOA permitted both focal (confined to single layers/columns), and widespread (multiple layers/columns) optogenetic activation of deep layer neurons, as assessed with multi-channel laminar electrode arrays, simply by varying the number of activated µLEDs and/or the irradiance. Thus, the UOA represents a powerful optoelectronic device for targeted manipulation of deep-layer circuits in NHP models
Space charge in ionization detectors and the NA48 electromagnetic calorimeter
The subject of space charge due to positive ions slowly moving in parallel plate ionization chambers is considered. A model for the degradation of the detector response is developed, with particular emphasis on electromagnetic calorimeters. The topics discussed include: (a) the stationary and (b) the time dependent cases; (c) the limit of very large space charge; (d) the electric field dependence of the electron drift velocity; (e) the effect of longitudinal development of showers; (f) the behavior of the average reductions of response and (g) the non-uniformity of response for different positions of the shower axis inside the cell defined by the electrodes. The NA48 calorimeter is used as application and for comparison of results
New high statistics measurement of decay form factors and scattering phase shifts
We report results from a new measurement of the decay by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670000 decays in both charged modes collected in 2003. The form factors of the hadronic current (F, G, H) and phase difference () have been measured in ten independent bins of the mass spectrum to investigate the variation. A sizeable acceptance at large mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the scattering lengths and . Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory
Addendum 2 to P253: a high sensitivity investigation of and neutral hyperon decays using a modified beam
Direct search for light gluinos
We present the results for a direct search for light gluinos through the appearance of with high transverse momentum in the vacuum tank of the NA48 experiment at CERN. We find one event within a lifetime range of s and another one between s. Both events are consistent with the expected background from neutrons in the beam, produced by 450 GeV protons impinging on the Be targets, which interact with the residual air in the tank. From these data we give limits on the production of the hypothetical bound state, the hadron, and its decay in the mass range between 1 and 5~GeV
Search for direct CP violating charge asymmetries in and decays
A measurement of the direct CP violating charge asymmetries of the Dalitz
plot linear slopes in and
decays by the NA48/2 experiment at CERN SPS is
presented. A new technique of asymmetry measurement involving simultaneous
and beams and a large data sample collected allowed a result of an
unprecedented precision. The charge asymmetries were measured to be
with
decays, and with
decays. The precision of the
results is limited mainly by the size of the data sample.Comment: 29 pages, 9 figures. An updated version accepted by the EPJ
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