To allow the online selection of events, the readout of the P̅ANDA detector will reconstruct particles online. Several algorithms to perform this task in one of the subsystems, the electromagnetic ...calorimeter, are being developed. The algorithms are discussed, and a simple test case shows that they appear to behave similarly in terms of the ability to reconstruct events, and the time it takes to do this. However, some peculiarities, like the fact that the algorithms show the best performance in what is expected to be the worst-case scenario, still require additional investigation.
Near-Edge X‑ray Absorption Mass Spectrometry of a Gas-Phase Peptide González-Magaña, O; Reitsma, G; Tiemens, M ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
11/2012, Letnik:
116, Številka:
44
Journal Article
Recenzirano
We have studied the dissociation of the gas-phase protonated peptide leucine enkephalin YGGFL+H+ upon X-ray absorption in the region of the C K-edge. The yield of photodissociation products was ...recorded as a function of photon energy. The total photoabsorption yield is qualitatively similar to near-edge X-ray absorption fine structure (NEXAFS) spectra recorded from condensed phase peptides and proteins. Fragment specificity reveals distinct quantitative differences between spectra obtained for different masses. Fragmentation channels can be assigned to specific electronic transitions some of which are site specific. For instance, C 1s → π★ excitations in the leucine enkephalin aromatic side chains lead to relatively little fragmentation, whereas such excitations along the peptide backbone induce strong fragmentation.
One of the physics goals of the future ANDA experiment at FAIR is to research newly discovered exotic states. Because the detector response created by these particles is very similar to the ...background channels, a new type of data readout had to be developed, called "triggerless" readout. In this concept, each detector subsystem preprocesses the signal, so that in a later stage, high-level phyiscs constraints can be applied to select events of interest. A dedicated clock source using a protocol called SODANET over optical fibers ensures proper synchronisation between the components. For this new type of readout, a new way of simulating the detector response also needed to be developed, taking into account the effects of pile-up caused by the 20 MHz interaction rate.
One of the physics goals of the future P A N D A experiment at FAIR is to research newly discovered exotic states. Because the detector response created by these particles is very similar to the ...background channels, a new type of data readout had to be developed, called "triggerless" readout. In this concept, each detector subsystem preprocesses the signal, so that in a later stage, high-level phyiscs constraints can be applied to select events of interest. A dedicated clock source using a protocol called SODANET over optical fibers ensures proper synchronisation between the components. For this new type of readout, a new way of simulating the detector response also needed to be developed, taking into account the effects of pile-up caused by the 20 MHz interaction rate.
The natural approach taken by organic agriculture obviates the use of synthetic agrochemicals and emphasizes farming in accordance with agroecological principles. Also implicit in this approach is an ...appreciation for the integrity of living farm organisms, with the integrity being evaluated from a biocentric perspective. The ethical value assigned to integrity of organisms has challenged us to develop criteria for evaluating both integrity and breeding techniques. For cultivated plants, integrity refers to their inherent nature, their wholeness, completeness, species-specific characteristics, and their being in balance with their (organically farmed) environment. We evaluate integrity using criteria derived from four different perspectives: integrity of life, plant-specific integrity, genotypic integrity, and phenotypic integrity. These criteria were used to assess whether existing breeding and propagation techniques violate the integrity of crop plants. In vitro techniques and techniques that engineer at the DNA level appeared to be incompatible with the integrity of crops, with the exception of use of DNA markers. On the other hand, breeding techniques that work at the level of breeding, evaluation, and selection for whole plant performance, and which do not break reproductive barriers between species, may conform to the principles of organic farming. In the selection process, the so-called breeder's eye can be developed to become a more consciously applied instrument for perceiving and assessing aspects of the wholeness or phenotypic integrity of a plant. Thus, the challenge given by the organic community to breeders implies the further development of scientific approaches, evaluation, and choice of breeding techniques, and the systematic development of the respectful and artful eye of the individual breeder.
We report the first measurement of absolute hadronic branching fractions of Λ_{c}^{+} baryon at the Λ_{c}^{+}Λover ¯_{c}^{-} production threshold, in the 30 years since the Λ_{c}^{+} discovery. In ...total, 12 Cabibbo-favored Λ_{c}^{+} hadronic decay modes are analyzed with a double-tag technique, based on a sample of 567 pb^{-1} of e^{+}e^{-} collisions at sqrts=4.599 GeV recorded with the BESIII detector. A global least-squares fitter is utilized to improve the measured precision. Among the measurements for twelve Λ_{c}^{+} decay modes, the branching fraction for Λ_{c}^{+}→pK^{-}π^{+} is determined to be (5.84±0.27±0.23)%, where the first uncertainty is statistical and the second is systematic. In addition, the measurements of the branching fractions of the other 11 Cabibbo-favored hadronic decay modes are significantly improved.
Using a low background data sample of 9.7×10^{5} J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII ...detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
The spin and parity of the Z_{c}(3900)^{±} state are determined to be J^{P}=1^{+} with a statistical significance larger than 7σ over other quantum numbers in a partial wave analysis of the process ...e^{+}e^{-}→π^{+}π^{-}J/ψ. We use a data sample of 1.92 fb^{-1} accumulated at sqrts=4.23 and 4.26 GeV with the BESIII experiment. When parametrizing the Z_{c}(3900)^{±} with a Flatté-like formula, we determine its pole mass M_{pole}=(3881.2±4.2_{stat}±52.7_{syst}) MeV/c^{2} and pole width Γ_{pole}=(51.8±4.6_{stat}±36.0_{syst}) MeV. We also measure cross sections for the process e^{+}e^{-}→Z_{c}(3900)^{+}π^{-}+c.c.→J/ψπ^{+}π^{-} and determine an upper limit at the 90% confidence level for the process e^{+}e^{-}→Z_{c}(4020)^{+}π^{-}+c.c.→J/ψπ^{+}π^{-}.
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