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> Instead, the CMS team relies on an algorithmic system apparently known as "the trigger" (Okay, are they deliberately trying to freak out TikTok?). The trigger

> Instead, the CMS team relies on an algorithmic system apparently known as "the trigger" (Okay, are they deliberately trying to freak out TikTok?). The trigger highlights only the potentially interesting collisions, allowing for consequential data to be stored, and the rest to be tossed out. The name "trigger" is actually a vert straightforward description of what it is doing. A trigger at CMS for example will have certain criteria and conditions (related with hits, tracks, geometry, etc.) of particles (or potential particle signals) and will only save events with specified information that will meet the specific criteria because you cannot save all data (waste of time and resources). And they are many triggers in reality, people usually in the field specify which trigger are you talking about, if not then it means the trigger system. Which is the system that controls the overall process of data accusation. So a trigger will be "triggered" when its conditions are met, hence the name. For example, if I'm not wrong (someone at CMS might correct me) the trigger in question will be a trigger on a displaced muon. So this analysis actually looked for displaced muons as final state (Assuming that dark photons will decay to those displaced muons) so you are looking to an excess of signal that expected (by other processes) which ("It depends" actually) might give an indication into dark photons.

magicalhippo 3y ago
> because you cannot save all data (waste of time and resources) AFAIK, at least for ATLAS and CMS, the sheer amount of raw data the sensors produce, like 40TB/s or more[1], requires using triggers to reduce the captured data rate. Even after that first trigger there's still over 100GB/s, which is too much for storing directly. Interestingly though, due to its design the LHCb detector has a lower intrinsic luminosity (ie less stuff happening) and so was able to move to a fully software-based trigger system[2]. This allows them to change the trigger parameters "at will", unlike the hardware-based first-level triggers of ATLAS and CMS which can't really be changed much once installed. [1]: https://www.annualreviews.org/doi/full/10.1146/annurev-nucl-102115-044713 https://www.annualreviews.org/doi/full/10.1146/annurev-nucl-... [2]: https://arxiv.org/abs/1410.5012 https://arxiv.org/abs/1410.5012

magicalhippo 3y ago

> because you cannot save all data (waste of time and resources) AFAIK, at least for ATLAS and CMS, the sheer amount of raw data the sensors produce, like 40TB/s or more[1], requires using triggers to reduce the captured data rate. Even after that first trigger there's still over 100GB/s, which is too much for storing directly. Interestingly though, due to its design the LHCb detector has a lower intrinsic luminosity (ie less stuff happening) and so was able to move to a fully software-based trigger system[2]. This allows them to change the trigger parameters "at will", unlike the hardware-based first-level triggers of ATLAS and CMS which can't really be changed much once installed. [1]: https://www.annualreviews.org/doi/full/10.1146/annurev-nucl-102115-044713 https://www.annualreviews.org/doi/full/10.1146/annurev-nucl-... [2]: https://arxiv.org/abs/1410.5012 https://arxiv.org/abs/1410.5012