A z-Vertex Trigger for Belle II Skambraks, S.; Abudinen, F.; Chen, Y. ...
IEEE transactions on nuclear science,
08/2015, Letnik:
62, Številka:
4
Journal Article
Recenzirano
The Belle II experiment will go into operation at the upgraded SuperKEKB collider in 2016. SuperKEKB is designed to deliver an instantaneous luminosity L = 8 ×10 35 cm - 2 s - 1 . The experiment will ...therefore have to cope with a much larger machine background than its predecessor Belle, in particular from events outside of the interaction region. We present the concept of a track trigger, based on a neural network approach, that is able to suppress a large fraction of this background by reconstructing the z (longitudinal) position of the event vertex within the latency of the first level trigger. The trigger uses the hit information from the Central Drift Chamber (CDC) of Belle II within narrow cones in polar and azimuthal angle as well as in transverse momentum ("sectors"), and estimates the z-vertex without explicit track reconstruction. The preprocessing for the track trigger is based on the track information provided by the standard CDC trigger. It takes input from the 2D track finder, adds information from the stereo wires of the CDC, and finds the appropriate sectors in the CDC for each track. Within the sector, the z-vertex is estimated by a specialized neural network, with the drift times from the CDC as input and a continuous output corresponding to the scaled z-vertex. The neural algorithm will be implemented in programmable hardware. To this end a Virtex 7 FPGA board will be used, which provides at present the most promising solution for a fully parallelized implementation of neural networks or alternative multivariate methods. A high speed interface for external memory will be integrated into the platform, to be able to store the O(10 9 ) parameters required. The contribution presents the results of our feasibility studies and discusses the details of the envisaged hardware solution.
The hadronic part of the electron structure function F2e has been measured for the first time, using e+e− data collected by the DELPHI experiment at LEP, at centre-of-mass energies of ...s=91.2–209.5 GeV. The data analysis is simpler than that of the measurement of the photon structure function. The electron structure function F2e data are compared to predictions of phenomenological models based on the photon structure function. It is shown that the contribution of large target photon virtualities is significant. The data presented can serve as a cross-check of the photon structure function F2γ analyses and help in refining existing parameterisations.
Calibration of the DELPHI HPC calorimeter during the LEP2 programme Feindt, M.; Grahl, J.; Kreuter, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1999, Letnik:
421, Številka:
1
Journal Article
Recenzirano
The readout chambers of the DELPHI HPC calorimeter are affected by large ageing which results in a module-dependent loss of gain. The calorimeter response thus needs to be tuned on a module-by-module ...basis. During the LEP operation phase at energies close to the Z resonance (LEP1), the tuning was based on the high available statistics of Z→e
+e
− events. In the high energy operation phase (LEP2), no such clear monochromatic physics channel is available with high statistics. A monitoring of the analog response of the readout chambers of each module is provided by the periodic calibration with radioactive
83
m
Kr; using this information to account for module-dependent effects ensures the stability of the energy resolution throughout the LEP2 programme.
Objective Anesthetic preconditioning may contribute to the cardioprotective effects of sevoflurane in patients having coronary artery bypass surgery. We investigated whether 2 different sevoflurane ...administration protocols can induce preconditioning in patients having coronary artery bypass. Methods Thirty patients were randomly allocated to 1 of 3 groups. All patients received a total intravenous anesthesia with sufentanil (0.3 μg−1 · kg· h−1 ) and propofol as target controlled infusion (2.5 μg/mL). The control group had no further intervention; 10 minutes prior to establishing the extracorporeal circulation, patients of the sevoflurane-I group received 1 minimum alveolar concentration of sevoflurane for 5 minutes. Patients of the sevoflurane-II group received (2 times) 5 minutes of sevoflurane, interspersed by 5-minute washout 10 minutes prior to extracorporeal circulation. Troponin I was measured as marker of cardiac cellular damage. Results Peak levels of troponin I release were observed at 4 hours after cardiopulmonary bypass and were not affected by 1 cycle of sevoflurane administration (controls: 14 ± 3 ng/mL vs sevoflurane-I group, 14 ± 3 ng/mL). Two periods of sevoflurane preconditioning significantly reduced cellular damage compared with controls (peak troponin I level sevoflurane-II group, 7 ± 2 ng/mL). Conclusion These data show that sevoflurane-induced preconditioning is reproducible in patients having coronary artery bypass but depends on the preconditioning protocol used.
Demand forecasting is a central component of the replenishment process for retailers, as it provides crucial input for subsequent decision making like ordering processes. In contrast to point ...estimates, such as the conditional mean of the underlying probability distribution, or confidence intervals, forecasting complete probability density functions allows to investigate the impact on operational metrics, which are important to define the business strategy, over the full range of the expected demand. Whereas metrics evaluating point estimates are widely used, methods for assessing the accuracy of predicted distributions are rare, and this work proposes new techniques for both qualitative and quantitative evaluation methods. Using the supervised machine learning method "Cyclic Boosting", complete individual probability density functions can be predicted such that each prediction is fully explainable. This is of particular importance for practitioners, as it allows to avoid "black-box" models and understand the contributing factors for each individual prediction. Another crucial aspect in terms of both explainability and generalizability of demand forecasting methods is the limitation of the influence of temporal confounding, which is prevalent in most state of the art approaches.
We present a search for lepton-flavor-violating tau decays into three leptons (electrons or muons) using 782 fb super(-1) of data collected with the Belle detector at the KEKB asymmetric-energy e ...super(+)e super(-) collider. No evidence for these decays is observed and we set 90% confidence level upper limits on the branching fractions between 1.5x10 super(-8) and 2.7x10 super(-8).
Study of aging effects in the HPC readout chambers Cattai, A.; De Min, A.; Feindt, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/1995, Letnik:
367, Številka:
1
Journal Article
Recenzirano
The readout chambers of the HPC calorimeter are affected by large aging. This stimulated intense experimental activity aimed at developing a reliable monitor of the evolution of the detector response ...and at understanding the origin of the aging. Both of these aspects are discussed. Particular attention is devoted to a series of tests performed with HPC units equipped with graphite inserts in the readout chambers.
Performance of the HPC calorimeter in DELPHI Chan, A.; Crawley, H.B.; Edsall, D.M. ...
IEEE transactions on nuclear science,
08/1995, Letnik:
42, Številka:
4
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The performance of the High-density Projection Chamber (HPC), the barrel electromagnetic calorimeter of the DELPHI experiment, is described. The detector adopts the time projection technique in order ...to obtain exceptionally fine spatial granularity in the three coordinates (/spl sim/2/spl times/20 mrad/sup 2/ in /spl theta//spl times//spl phi/ with nine samplings along the shower axes), using a limited number of readout channels (18432). Among the various topics concerning the HPC construction and operation, major emphasis is given to the aspects related to the calibration in energy of the calorimeter, based mainly on the analysis of the detector response to /sup 83m/Kr decays, and to the treatment of ageing in the readout proportional counters.< >
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