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Andres Florez | USLHC | USA

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Life as a shifter…..

Life as a shifter…..

As part of the contribution with CMS, every University should do a number shifts when the experiment is taking data. For those no familiar with this, you might be wondering, how it is possible that we are taking data if the LHC haven’t started yet? Well, we are being bombarded by millions of cosmic rays every day, and those are the source that we use to understand our detectors and  find problems with the hardware and software. I have being taking some shifts for offline Data Quality Monitoring (DQM) for the tracker system and online shifts for the pixel detector.

For DQM shifts, you should go over the data that have been taken and check some specific plots in order to see the performance and/or errors generated during that particular run. It is cool to go over the different plots and see the efficiency  of each component of the tracker system (silicon strip tracker and the pixel detector).  It is important to see and try to understand the different errors that were generated during the run and report them (if they haven’t been reported before) to the shift leader. The shift leader is the person that usually saves you when you have no idea of what to do. Thanks to all of them!

Pixel online is super nice, but carries a lot more responsibility! Basically, you are baby-sitting a several million dollars detector and believe me, you don’t want to screw things up for not being aware of what you are doing…..During the shift, you should keep track of the temperature, humidity, voltages and currents of the detector (in this case the pixel detector)….Other important issue are the Front End Drivers (FEDs). These are electronic cards used for the detector control and readout. Personally, I believe that the FEDs are one of  the most complicated and important devices in the experiment and if something goes wrong with them, you better pay attention to it!

In general you never know how your shift is going to be. It could be smooth and you almost don’t have to do much during 8 hours, or it could be really busy and stressful, but in the end fun (sometimes). Usually, I get shifts where weird things happen (I think that the detector is a live and it doesn’t like me)…….

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One Response to “Life as a shifter…..”

  1. Dear Andres,

    What are the “weird things” you were talking about? Maybe you’re just sensitive to normal fluctuations in operations (i.e. you falsely trigger positively for an “event” of some sort – in this case a “sensor mishap” or what could I call it like)? Do you have a strict set of (technical) rules to comply to when you jugde an event as ordinary or extraordinary?

    I’d guess the protection against “hard errors” (which could break equipment – voltage too high eg.) would be implemented as an automatic beyond human control (think circuit breakers), can you confirm that?

    I’m just asking because I often see people (including myself) getting confused over complicated readouts and reports. And I’d take any bet the monitoring suite for CMS is pretty complicated.

    Any way, I’d love to hear more about what it’s like to monitor a detector of this dimension. Do you ever feel pressure beyond time restrictions (“we need to go online at 10 straight”)? Do you do physics (or mathematics) on paper for your work? Can you let your readers see some of the plots you’ve been talking about?

    Regards,
    Basti

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