The goal of the Mu2e experiment at Fermilab is to search for charged-lepton flavor violation by looking for neutrino-less muon to electron conversion in the field of the nucleus. The Mu2e ...experimental apparatus utilizes a complex magnetic field in the muon generation and momentum and charge selection process. Precise knowledge of the magnetic field is crucial. It is planned to map the solenoid field with calibrated three-dimensional (3-D) Hall probes up to 10 -5 accuracy. This article describes a new design of a Hall probe calibration system that will be used to calibrate 3-D Hall probes to better than 10 -5 accuracy for the Mu2e solenoid field mapping system.
Mu2e Solenoid Field Mapping System Design Feher, Sandor; DeLurgio, Patrick; Elementi, Luciano ...
IEEE transactions on applied superconductivity,
04/2018, Letnik:
28, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The Mu2e experiment at Fermilab plans to search for charged-lepton flavor violations by looking for neutrino-less muon to electron conversions in the field of the nucleus. A complex solenoid system ...and precise knowledge of its magnetic field play a major role in the experimental approach Mu2e has chosen. It is essential to map the solenoid field up to 10 -4 accuracy. This article describes the design of the Field Mapping System Mu2e will use to measure the magnetic field. Two different mechanical mapper systems, a survey-based position determination of the in-house calibrated three-dimensional Hall probes, a motion control system, and a data acquisition and readout system are presented.
Third-octave-mode chatter in rolling. Part 1: Chatter model Hu, Pei-Hua; Zhao, Huyue; Ehmann, K F
Proceedings of the Institution of Mechanical Engineers. Part B, Journal of engineering manufacture,
08/2006, Letnik:
220, Številka:
8
Journal Article
Recenzirano
Abstract
Among various types of rolling chatter, third-octave-mode chatter is considered the most critical because it generates large gauge variations in the rolled materials and may damage the ...rolling mill. In this three-part paper, a new chatter model that combines a homogeneous process model with suitable mill structure models is presented. Based on this model, the system's stability is investigated in the light of various mechanisms that may lead to the onset of third-octave-mode chatter. Stability criteria for each mechanism are established in terms of relevant rolling process parameters, and their influences on overall system stability are demonstrated. Part 1 deals with the general formulation of single- and multiple-stand chatter models.
Abstract
Based on the general linear chatter model of a single-stand mill, derived in Part 1, two physical mechanisms that may lead to chatter will be explored. The first, termed instability caused ...by the ‘model-matching effect’, is the consequence of a simple process-structure interaction that exhibits a relatively high margin of stability. The second, ‘mode coupling’, is the consequence of multiple vibration modes. The stability of both chatter modes will be established by formulating analytical stability criteria in terms of relevant rolling process parameters. Simulation results will be presented to demonstrate stable and unstable mill behaviour.
A newly developed theory for the analysis of tapered sandwich panels with laminated anisotropic facings is presented. Unlike sandwich panels of uniform depth, the response of tapered sandwich panels ...is counterintuitive. For example, prior studies have demonstrated that a tapered cantilever sandwich beam having constant dimensions at the clamped edge and subjected to a tip load has an optimum taper angle where the tip deflection is a minimum. The decrease in tip deflection with increasing taper angle, despite the reduction in core thickness, is due to the participation of the facings in resisting transverse shear loads. In the present work, we systematically develop a tapered sandwich theory that is simple to use, yet accurately predicts the stresses and deflection of both symmetric and nonsymmetric tapered sections. A novel feature of the analytical model is that the elastic rigidities of tapered sandwich composites are expressed in terms of the familiar A, B, and D matrices that are widely used to analyze the response of laminated plates and sandwich beams of uniform depth. It is shown that the stiffness matrix for a tapered sandwich member exhibits a total of 12 elastic couplings that are absent in sandwich beams of uniform depth. The analytical model predicts large interlaminar shear and normal stresses near the root of the tapered sandwich beam, which can cause delamination failure between the facings and the core. Numerical results obtained using the tapered sandwich theory and two-dimensional finite element models are in good agreement for several case studies.
Abstract
The stability of a tandem mill is analysed by considering interstand interactions. In this part of the paper the stability of the multistand multimodal chatter model, developed in Part 1 1, ...is ascertained. The general model is represented in a simplified form, which highlights only phenomena caused by strip velocity, or equivalently, strip tension variations between stands. This mechanism constitutes one of the most critical sources of self-excitation in the operation of tandem mills and leads to the most detrimental effects associated with third-octave mode chatter. As before, the theoretical analysis of the stability conditions is followed by a simulation study that shows the major dynamic trends in the mill's behaviour.
Development of a low-cost fast-timing microchannel plate photodetector Xie, Junqi; Byrum, Karen; Demarteau, Marcel ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We report on the design, fabrication and characterization of a prototype 6×6cm2 microchannel plate photodetector with precise fast-timing measurement capability. The whole assembly is made of low ...cost glass materials with a bialkali photocathode top window. All components are hermetically sealed in vacuum. The prototype photodetector exhibits time resolution of 65ps and 16ps at single-photoelectron and multi-photoelectron levels, respectively. The spatial resolution reaches 0.54mm for multi-photoelectron measurements. The bialkali photocathode exhibits a maximum quantum efficiency exceeding 20% with a uniformity of ±40%.
Microchannel plate photodetectors, capable of picosecond time resolution and sub-mm spatial resolution, are a perfect candidate for the next generation of photodetectors for precision timing ...measurements. Argonne National Laboratory is producing low-cost, all-glass body, planar photodetectors with an indium seal. The design and fabrication of 6-cm square photodetectors has been well demonstrated in an ultra-high vacuum system. Recently, a new design was developed to optimize the photodetector bias voltage. This design offers an improved configuration and allows external control of the bias voltage for each internal detector component. Design and measurements of the new independently biased devices are described in this paper. We performed a systematic study on the bias voltage and achieved a gain on the order of 10 7 , a time resolution better than 35 ps, and a spatial resolution better than 1 mm.
Micro-channel plate (MCP)-based photodetectors are capable of picosecond level time resolution and sub-mm level position resolution, which makes them a perfect candidate for the next generation large ...area photodetectors. The large-area picosecond photodetector (LAPPD) collaboration is developing new techniques for making large-area photodetectors based on new MCP fabrication and functionalization methods. A small single tube processing system (SmSTPS) was constructed at Argonne National Laboratory (ANL) for developing scalable, cost-effective, glass-body, 6cm×6cm, picosecond photodetectors based on MCPs functionalized by Atomic Layer Deposition (ALD). Recently, a number of fully processed and hermitically sealed prototypes made of MCPs with 20μm pores have been fabricated. This is a significant milestone for the LAPPD project. These prototypes were characterized with a pulsed laser test facility. Without optimization, the prototypes have shown excellent results: the time resolution is ~57ps for single photoelectron mode and ~15ps for multi-photoelectron mode; the best position resolution is ≤0.8mm for large pulses. In this paper, the tube processing system, the detector assembly, experimental setup, data analysis and the key performance will be presented.
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