Ultrasound Defect Localization in Shell Structures with Lamb Waves Using Spare Sensor Array and Orthogonal Matching Pursuit Decomposition

Lamb waves have multimodal and dispersion effects, which reduces their performance in damage localization with respect to resolution. To detect damage with fewest sensors and high resolution, a method, using only two piezoelectric transducers and based on orthogonal matching pursuit (OMP) decomposition, was proposed. First, an OMP-based decomposition and dispersion removal algorithm is introduced, which is capable of separating wave packets of different propagation paths and removing the dispersion part successively. Then, two simulation signals, with nonoverlapped and overlapped wave packets, are employed to verify the proposed method. Thereafter, with the proposed algorithm, the wave packets reflected from the defect and edge are all separated. Finally, a sparse sensor array with only two transducers succeeds in localizing the defect. The experimental results show that the OMP-based algorithm is beneficial for resolution improvement and transducer usage reduction.

Performance of Michigan sMDT prototype chambers for the HL-LHC ATLAS muon detector upgrade

A new small-diameter Monitored Drift Tube (sMDT) chamber has been developed for the muon spectrometer of the ATLAS experiment to handle the higher collision rates expected at the CERN High Luminosity Large Hadron Collider (HL-LHC). This paper presents measurements of the tracking resolution and hit efficiency of two prototype sMDT chambers constructed at the University of Michigan. Using cosmic-ray muons the sMDT tracking resolution of 103.7 ± 8.1 μm was measured for one chamber and 101.8 ± 7.8 μm for the other, compared with a design resolution of 106 μm. A further tracking resolution improvement to 83.4 ± 7.8 μm was obtained by using new high-gain readout electronics which will be added for HL-LHC. An average tracking efficiency of (98.5 ± 0.2)% was found for both chambers. The methodology used to determine the detector tracking resolution and efficiency, including reconstruction of sMDT data and a Geant4 simulation of the test chamber, is presented in detail.

Improving Diagnosis Resolution with Population Level Statistical Diagnosis

In this paper, we present a diagnosis resolution improvement methodology for scan-based tests. We achieve 89% reduction in the number of suspect diagnosis locations and a 2.4X increase in the number of highly resolved diagnosis results. We suffer a loss in accuracy of 1.5%. These results were obtained from an extensive silicon study. We use data from pilot wafers and 11 other wafers at the leading-edge technology node and check against failure analysis results from 203 cases. This resolution improvement is achieved by considering the diagnosis problem at the level of a population (e.g. a wafer) of failing die instead of analyzing each failing die completely independently as has been done traditionally. Higher diagnosis resolution is critical for speeding up the yield learning from manufacturing test and failure analysis flows.

Submicron Non-contact Simultaneous Infrared and Raman Spectroscopy for Challenging Failure Analysis

We introduce a new infrared (IR) technique that provides submicron spatial resolution by making use of an infraredvisible, pump-probe arrangement that also offers a simultaneous Raman measurement in formerly challenging failure and contamination analyses. These challenges are typically due to the lack of spatial resolution and sample preparation restrictions from conventional FTIR, plus auto-fluorescence (AF) from Raman spectroscopy. Such a combined Optical PhotoThermal InfraRed (O-PTIR) and Raman instrumentation offers spatial resolution improvement over conventional IR measurements by 30 times at 1000 cm-1. The technique also improves sensitivity to exceptionally small quantities (? 400 femtogram) in reflection mode by sensing the photothermal response arising from absorbing infrared radiation (Fig. 1) [1]. The AF-free O-PTIR technique also delivers constant spatial resolution over the entire mid-IR range due to the use of a fixed wavelength probe beam at 532 nm [2]. Simultaneous Raman confirms and complements the O-PTIR measurements in cases with low AF. We will illustrate three examples that will highlight the advantage of the novel technique commonly observed in the failure and contamination analysis community.