No Arabic abstract
The National Ignition Facility (NIF) will contain the worlds most powerful laser. NIF requires more than 1500 precisely timed trigger pulses to control the timing of laser and diagnostic equipment. The Integrated Timing System applies new concepts to generate and deliver triggers at preprogrammed times to equipment throughout the laser and target areas of the facility. Trigger pulses during the last 2 seconds of a shot cycle are required to have a jitter of less than 20 ps (rms) and a wander of less than 100 ps (max). Also, the Timing System allows simultaneous, independent use by multiple clients by partitioning the system hardware into subsets that are controlled via independent software keys. The hardware necessary to implement the Integrated Timing System is commercially available. -- This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.
A highly stable monitoring system based on blue and red light emitting diodes coupled to a distribution network comprised of optical fibers has been developed for an electromagnetic calorimeter that uses lead tungstate crystals readout with photomultiplier tubes. We report of the system prototype design and on the results of laboratory tests. Stability better than 0.1% (r.m.s.) has been achieved during one week of prototype operation.
The MEG detector is designed to test Lepton Flavor Violation in the $mu^+rightarrow e^+gamma$ decay down to a Branching Ratio of a few $10^{-13}$. The decay topology consists in the coincident emission of a monochromatic photon in direction opposite to a monochromatic positron. A precise measurement of the relative time $t_{e^+gamma}$ is crucial to suppress the background. The Timing Counter (TC) is designed to precisely measure the time of arrival of the $e^+$ and to provide information to the trigger system. It consists of two sectors up and down stream the decay target, each consisting of two layers. The outer one made of scintillating bars and the inner one of scintillating fibers. Their design criteria and performances are described.
We performed a detailed study of the timing performance of the LHCb VELO Timepix3 Telescope with a 180 GeV/c mixed hadron beam at the CERN SPS. A twofold method was developed to improve the resolution of single-plane time measurements, resulting in a more precise overall track time measurement. The first step uses spatial information of reconstructed tracks in combination with the measured signal charge in the sensor to correct for a mixture of different effects: variations in charge carrier drift time; variations in signal induction, which are the result of a non-uniform weighting field in the pixels; and lastly, timewalk in the analog front-end. The second step corrects for systematic timing offsets in Timepix3 that vary from -2 ns to 2 ns. By applying this method, we improved the track time resolution from 438$,pm,$16 ps to 276$,pm,$4 ps.
The MINERvA experiment is designed to perform precision studies of neutrino-nucleus scattering using $ u_mu$ and ${bar u}_mu$ neutrinos incident at 1-20 GeV in the NuMI beam at Fermilab. This article presents a detailed description of the minerva detector and describes the {em ex situ} and {em in situ} techniques employed to characterize the detector and monitor its performance. The detector is comprised of a finely-segmented scintillator-based inner tracking region surrounded by electromagnetic and hadronic sampling calorimetry. The upstream portion of the detector includes planes of graphite, iron and lead interleaved between tracking planes to facilitate the study of nuclear effects in neutrino interactions. Observations concerning the detector response over sustained periods of running are reported. The detector design and methods of operation have relevance to future neutrino experiments in which segmented scintillator tracking is utilized.
We present the final results from a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC). This detector was designed as a full-scale prototype of the particle identification system for the SuperB experiment [1], and comprises 1/12 of the SuperB barrel azimuthal coverage, with partial photodetector and electronics implementation. The prototype was tested in the SLAC Cosmic Ray Telescope which provided 3-D tracking of cosmic muons with an angular resolution of ~1.5 mrad, a position resolution of 4-5 mm, a start time resolution of 70 ps, and muon tracks above ~2 GeV tagged using an iron range stack. The fused silica focusing photon camera was coupled to a full-size BaBar DIRC bar box and was read out, over part of the full coverage, by 12 Hamamatsu H8500 multi-anode photomultipliers (MaPMTs) providing 768 pixels. We used waveform digitizing electronics to read out the MaPMTs. We give a detailed description of our data analysis methods and point out limitations on the present performance. We present results that demonstrate some basic performance characteristics of this design, including: (a) single photon Cherenkov angle resolutions with and without chromatic corrections, (b) signal-to-noise (S/N) ratio between the Cherenkov peak and background, which primarily consists of ambiguities of the possible photon paths from emission along the track to a given pixel, (c) dTOP = TOP_measured - TOP_expected resolutions (with TOP being the photon Time-of-Propagation in fused silica), and (d) performance of the detector in the presence of high-rate backgrounds.