Rare B → baryon decays from CLEO Thayer, Jana B.
The European physical journal. C, Particles and fields,
7/2004, Letnik:
33, Številka:
S1
Journal Article
Recenzirano
Odprti dostop
AbstractWe have searched for baryon-containing radiative penguin decays in 9.7 × 106\(B\bar{B}\) events collected at the Υ(4S) with the CLEO detector. We find no evidence for such decays, and set a ...90% confidence level upper limit of \({\cal B} (B \rightarrow X_s \gamma, X_s ~{\it containing~baryons}) _{E_\gamma > 2.0 \rm{~GeV}} < 3.8 \times 10^{-5}\). Corrections to CLEO’s recent b → sγ measurement due to \(B \rightarrow X_s({\it baryon}) \gamma\) decays are well within the errors quoted. A search for semileptonic decays of B mesons to \(e\bar{p}\) inclusive final states in the same data sample found no evidence for such decays and set an upper limit of \({\cal B} (B \rightarrow \bar{p} e^- \bar{\nu}_e X) < 5.9 \times 10^{-4}\). These limits suggest that external W emission is not the dominant source of baryon production in B decay.PACS: 13.20.HeDecays of Bottom Mesons – 13.40.HqElectromagnetic Decays – 13.60.RjBaryon Production
Building a Data System for LCLS-II Thayer, Jana B.; Carini, Gabriella; Kroeger, Wilko ...
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC),
2017-Oct.
Conference Proceeding
The volume of data generated by the upcoming LCLS-II upgrade will present a considerable challenge for data acquisition, data processing, and data management. According to current estimates, one ...instrument could generate instantaneous data rates of hundreds of GB/s. In this highthroughput regime, it will be necessary to reduce the data on-thefly prior to writing it to persistent storage. Even with data compression, it is expected that operating all four new instruments will produce an estimated 100 PB of data in the first year alone. We present a description of the envisioned LCLS-II Data System, which provides a scalable data acquisition system to acquire shot-by-shot data at repetition rates up to 1 MHz, an inline data reduction pipeline that provides a configurable set of tools including feature extraction, data compression, and event veto to reduce the amount of data written to disk, an analysis software framework for the timely processing of this data set, and an expanded data management system for accessing experiment data and meta-data.
The development of X-ray Free Electron Lasers (XFELs) has opened numerous opportunities to probe atomic structure and ultrafast dynamics of various materials. Single Particle Imaging (SPI) with XFELs ...enables the investigation of biological particles in their natural physiological states with unparalleled temporal resolution, while circumventing the need for cryogenic conditions or crystallization. However, reconstructing real-space structures from reciprocal-space x-ray diffraction data is highly challenging due to the absence of phase and orientation information, which is further complicated by weak scattering signals and considerable fluctuations in the number of photons per pulse. In this work, we present an end-to-end, self-supervised machine learning approach to recover particle orientations and estimate reciprocal space intensities from diffraction images only. Our method demonstrates great robustness under demanding experimental conditions with significantly enhanced reconstruction capabilities compared with conventional algorithms, and signifies a paradigm shift in SPI as currently practiced at XFELs.
The advent of next-generation X-ray free electron lasers will be capable of delivering X-rays at a repetition rate approaching 1 MHz continuously. This will require the development of data systems to ...handle experiments at these type of facilities, especially for high throughput applications, such as femtosecond X-ray crystallography and X-ray photon fluctuation spectroscopy.Here, we demonstrate a framework which captures single shot X-ray data at the LCLS and implements a machine-learning algorithm to automatically extract the contrast parameter from the collected data. We measure the time required to return the results and assess the feasibility of using this framework at high data volume. We use this experiment to determine the feasibility of solutions for 'live' data analysis at the MHz repetition rate.
The advent of next-generation X-ray free electron lasers will be capable of delivering X-rays at a repetition rate approaching 1 MHz continuously. This will require the development of data systems to ...handle experiments at these type of facilities, especially for high throughput applications, such as femtosecond X-ray crystallography and X-ray photon fluctuation spectroscopy. Here, we demonstrate a framework which captures single shot X-ray data at the LCLS and implements a machine-learning algorithm to automatically extract the contrast parameter from the collected data. We measure the time required to return the results and assess the feasibility of using this framework at high data volume. We use this experiment to determine the feasibility of solutions for `live' data analysis at the MHz repetition rate.
