Stave Core QA - ISU

Introduction

This page is dedicated to the ISU Stave Core QA methods. As a part of the ATLAS Phase-II Upgrade the inner tracker of ATLAS will be replaced. The inner tracker is composed of "staves" and "petals" that will contain silicon strip sensors. Currently there are 392 staves in the design and each stave will support 14 identical silicon strip sensor modules on each side (for a total of 28 modules per stave). Each stave consists of a sandwich formed by two face-sheets which contain low-density carbon-fiber honeycomb structures and titanium cooling pipes embedded in high thermal conductivity foam. For a very technical review of the inner tracker upgrade look at the ATLAS TDR where the information about the stave cores is located in chapter 9.

Currently there are two main methods being developed at ISU, Thermal Imaging and Laser Scanning. Both methods are ways to find flaws in manufactured staves such that during production extremely flawed staves can be spotted early in the production process.

The ISU HEP ATLAS group has been working on developing these methods over the last few years and previous meetings of the group can be found at Weekly Stave QC Meeting-Part I and Weekly Stave QC Meeting-Part II and Weekly Stave QC Meeting- Part III.

Thermal Imaging Method

This method uses IR images of a stave core to spot delaminations between the pipe and foam and the foam and the face-sheets. For more information about this method click here.

An IR picture of Stave Core 5

Laser Scanning Method

This method uses a laser scanning system to detect delaminations between the facing and internal structure of the stave. For more information about this method click here.

A laser scanned image of Stave Core 2R compared to the implemented flaws

Results and Presentations

Currently we have analyzed four full staves and a short stave.

• Short-Stave This was the initial mock stave used to test the idea of the thermal imaging. It was only 1/3 the length of a full production stave and it had intentional defects only on one side.
• Stave 2 This was the first full mock stave with intentional defects. It was utilized until it became damaged due to a fall that broke the cooling pipes.
• Stave 3 This mock stave was supposed to have no defects and was originally called the "flawless" stave. Upon examinations it was found to have many unexplained defects and was returned to Yale.
• Stave 2R This mock stave had more intentional defects than Stave 2. Both Stave 2 and Stave 2R have many intentional defects to help in the characterization of defects found in both thermal imaging and laser scanning.
• Stave 5 This mock stave was considered a "perfect" mock stave. The manufacturing and sealing of this stave allowed it to be quickly measured and sent on for future testing with the silicon strip sensors attached. No major defects were noticed in our observations.

Each stave with implemented defects, had each one categorized and they can be found here.

Below are some Important Presentations:

• 2016 Itk Week Presentation: This presentation shows images of the Short-Stave and initial use of the laser scanning method.
• 2017 Itk Week Presentation: This presentation has our most recent results for a flawless stave(Stave 5) and reiterates what has been learned from the beginning.
• Oct 2017 Stave Core Workshop: This is the indico page that includes the current state of the Itk stave cores.

-- CarlosMiguelVergelInfante - 2017-02-08 -- WilliamDaleHeidorn - 2017-09-20