Travis and I walked down X-beam manifold in chamber to investigate unknown contamination on the interior wall that Betsy had spotted, a few feet away from oplev flange/baffle. We found two dark brown/black spots near the top/roof of tube, each about the size of a quarter. I was able to scrape some off with a little flat head screw driver and then wipe with IPA wipes to improve/reduce the spots (grinding is needed to remove all). Before and after pictures attached. I wiped until there was no evidence of contaminate on wipe. Then we noticed the side wall was splattered with the same material (photo attached). Its first layer comes off by scraping with a tool, but we did not spend time scraping all 50-some spots. We can go back in to scrape these other spots, but I would first like to send sample in for analysis.

Note that we have seen evidence of higher pressures in XBM (compared to YBM) when it's isolated from beam tube. Could be outgassing from this material. Travis and I inspected YBM and did not find this contaminate.