1. Readout Board Design for Gas Electron Multiplier Detectors for Use in a Proposed Upgrade of the CMS Hadron Calorimeter Elizabeth Starling Marcus Hohlmann Kimberley Walton, Aiwu Zhang [March 7 th, 2014]

2. Introduction Each layer of the CMS detector is designed to stop/measure a different kind of particle. The hadron calorimeter (HCAL) is one of these layers. 1)Hadrons enter HCAL 2)They interact with the brass absorber material and create showers 3)The energy of the shower, which we can measure, is proportional to the energy of the particle! March 7th, 2014Florida Academy of Sciences2

3. The Problem However, HCAL has its limits. Can: measure the scintillation energy of the particles, Cannot: measure their position or movement within the detector. If we want more data, we need to upgrade the calorimeter such that it can see particle flow as well as energies – from a hadron calorimeter (HCAL) to a particle flow calorimeter (PFCAL). March 7th, 2014Florida Academy of Sciences3

4. The Solution! Unlike HCAL’s current design, GEM detectors can easily detect the location of particle hits – we’ve used this fact to our advantage for our muon tomography station. We need to design a readout board that will be capable of accurately measuring the location of each particle hit on the GEM detector. The solution: a segmented pad readout board! March 7th, 2014Florida Academy of Sciences4

5. Design – Basics March 7th, 2014Florida Academy of Sciences5 Hadron showers are large! They can be several centimeters across, so the pads can be wider than the strips from previous readout boards! Detectors will be “sandwiched” in-between brass absorber plates – these plates cause the showers that the GEM detectors can then pick up.

6. Design – Square Pads 10 cm x 10 cm active area 11 rows of 11 square pads: 121 total. Each pad is: 8.975 mm x 8.975 mm March 7th, 2014Florida Academy of Sciences6

7. Design – Square Pads All read-out components are routed to a single APV: 2 ground connections (top left, bottom right) 121 pad connections 5 auxiliary connectors – to allow for easier “plug-and- play” access when testing the boards March 7th, 2014Florida Academy of Sciences7 Panasonic footprint

8. Design – Square Pads March 7th, 2014Florida Academy of Sciences8 All pads are routed underneath each other on a mid-layer. Does cross-talk make a measureable difference? To find out, we routed three rows all the way across!

9. Design – Chevrons 10 cm x 10 cm active area “Zig-zag”-style chevrons! Chevron pads give us different information than the square pads, and improves upon the shower descriptions. Because of the different horizontal segmentation, the charge sharing between adjacent pads can tell us more about the particles and their positions! March 7th, 2014Florida Academy of Sciences9

10. Design – Chevrons In order to maintain the square shape of the active area and keep to a single Panasonic connector, we used three types of pads: 110 full-chevron pads – formed by cutting the square pads diagonally in half and flipping one half. 12 half-chevron pads to “fill in” the main square! 5 merged half-chevron pads, to fit to a single APV March 7th, 2014Florida Academy of Sciences10

11. What’s Next Have the boards produced by outside industry Test the boards: – Do they accomplish our goals? – What differences do we see between the square and chevron pads? Make a square “pixel” style board, with 9 square pixels for every 1 square pad. – Is this possible at the 10x10 scale? Routing? March 7th, 2014Florida Academy of Sciences11

12. What’s Next March 7th, 2014Florida Academy of Sciences12 121 square pads1,089 square pixels

13. References Image on slides #2, 5: http://en.wikipedia.org/wiki/Compact_Muon_Solenoid March 7th, 2014Florida Academy of Sciences13