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Aidan Randle-Conde | Université Libre de Bruxelles | Belgium

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Shifting expectations

It’s 2012. We have stable beams. We’re at 8TeV. We’re taking data and I’m sitting in the ATLAS Control Room again. Fans of my blog will remember my previous on-shift posts and, yes, today I had an awesome breakfast of roasted duck (a special treat from a visiting professor).

So ATLAS Control Room, we meet again...

So ATLAS Control Room, we meet again...

The last time I took shifts was about 6 months ago, and since we’ve had a shutdown. Both the LHC and ATLAS have used this break as an opportunity to make substantial improvements and move things around a bit. The change to 8TeV came at the same time as a change in the luminosity calibration. For some reason it looks like CMS are getting about 10% more collisions than ATLAS is. That’s a little unnerving.

The writing's on the wall, literally.  CMS have more collisions than we do.

The writing's on the wall, literally. CMS have more collisions than we do.

As the beam conditions changed, so has the Trigger Shifter’s desk. Performing the checks used to take me about 20 minutes, but with the new layout it took me one hour. Hopefully as I get used to the new system it will be quicker! Since I’m supposed to perform these checks about once an hour I could spend my whole shift staring at one set of histograms! That’s the kind of environment that leads to simple mistakes which could cost data.

Just when things were going well I heard a sound over the intercom and all my trigger rates dropped to 0Hz. There were no error messages, nothing seemed to be wrong with the detector and every system seemed to be working fine. After discussing the situation with colleagues in the Control Room I realized that it was a scheduled beam dump. A scheduled beam dump. We don’t get those often, and the training doesn’t include an MP3 file of the “scheduled beam dump” sound. But then again it’s 1:00am and it’s been 6 months since I was last on shift, so I think I can be forgiven for forgetting what a scheduled beam dump sounds like.

Discussing the beam dump with the other shifters.

Discussing the beam dump with the other shifters.

I’ll be on shift for the tonight and the next two night, racking up credit for SMU and keeping the trigger alive. If all goes well it’s a good chance to catch up on work, write a few blog posts and get some time to ponder the bigger challenges in my analyses. For a few days I’m essentially free from all meetings and distractions, giving me the time and space to sort out all the little problems that have built up in the past few weeks. The broken code, the old E-mails, the unasked questions. Shifts are great.

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  • ablaoubas

    What does credit for SMU mean?

  • http://aidanatcern.wordpress.com Aidan Randle-Conde

    Good question! I work for SMU (Southern Methodist University) and every institution affiliated with ATLAS has a quota of shifts that it is expected to complete. Every time I take a shift I get shift credit for myself and SMU, and this way when it comes to balancing the books we can demonstrate that I’ve done my part with respect to taking shifts.