Comment from Christine Nattrass

[200.202(e), 200.220] To Whom it May Concern: I am a nuclear physics professor at the University of Tennessee, Knoxville. I am writing in my personal capacity to oppose the proposed revisions to sections 200.202(e) and 200.220 that would restrict international scientific collaboration and isolate American scientists. I have spent my entire professional career in international high energy nuclear physics collaborations. I did my PhD on the STAR collaboration at RHIC at BNL on Long Island, I did my post doc on the ALICE collaboration at CERN and the PHENIX experiment at BNL, and I am currently in the sPHENIX, PHENIX, and EPIC experiments at Brookhaven as well as the JETSCAPE collaboration. These collaborations worked together to quantify the properties of nuclear matter at extreme temperatures, the hottest form of matter created in the laboratory. The US has invested literally billions of dollars in building and supporting collider experiments. These experiments require a lot of people to make them work - to analyze the data, but also to run the experiment. US-based experiments in my field are typically at least half based abroad. We literally would not have enough people to successfully run these experiments if we cannot have international collaborations. We could not recruit the best people, both because some people would be excluded by nationality and because it would inherently make the work environment hostile and dysfunctional. We have already been impacted by bans on Russian nationals entering national labs. We were not told in advance, but people scheduled for shifts were turned away at the gates after arriving. This meant that the collaborations had to suddenly find replacements. The instability in particular is destabilizing. We've known for years that you cannot get someone with Iranian citizenship access to a national lab, but when the banned list is a political football, I might very well have a graduate student who is suddenly banned from access to their thesis data. As the number of banned countries expands, it is too easy to accidentally violate these rules - especially when they are applied retroactively. Entire subfields of nuclear physics quite simply could not exist in the US if this is passed. It would make the US a much less appealing place for young talent - also people born and raised in the US - leading to a brain drain. The only impact on competitiveness would be to make us less competitive, as it would significantly reduce our ability to train young scientists.