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LHCb beam and background observations 25ns vs 50ns

LHCb beam and background observations 25ns vs 50ns. LBS Meeting, 13 May 2013. Disclaimer. 1. Background conditions in LHCb always very favourable 50 ns all along , 25ns as well ( even if statistics very limited )

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LHCb beam and background observations 25ns vs 50ns

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  1. LHCb beamand background observations 25ns vs 50ns LBS Meeting, 13 May 2013

  2. Disclaimer • 1. Background conditions in LHCb alwaysveryfavourable • 50 ns allalong, 25ns aswell (evenifstatisticsverylimited) • 2. LHCb performedmanytestsat 25ns, with both the LHCb detector and the beam/background monitors • difficult to disentangle and compare • 3. Consideredfills with samemagnetpolarity (DOWN, or +) • however, crossing angle applieddifferentlyat 50ns and 25ns • 50 ns tilted, 25ns on horizontalplane •  Bottom line isthatno big differenceswereobserved • Nothingextremelyexcitinghere

  3. 25ns vs 50ns runningconditions • Comparisons 25ns vs 50 ns takinginto account samerunningconditions • Fill 3360 vs 3453 • Fast background estimation: losses over 10 consecutive BXIDs • At 25ns, higher due to consecutive bunches • Values are compatible, no big differences

  4. At injection/ramp • Injectionalsoveryclean • Some fast lossesat 25ns butstillverylow • Fast lossesduringcollisionsprocess, butcomparablebetween 25ns and 50ns 25ns 50ns

  5. Luminousregion From VELO detector  In 50ns, Z moves to about +45mm, thenslowlydrifts back again to +20mm  In 25ns, Z steady at +10mm

  6. Beam gas rates25ns vs 50ns • Biggestdifferenceis with beam-gas rates • Seems to be present a contributionfrom long rangeat 25ns 25ns 50ns

  7. Conclusion •  Bottom line isthatno big differenceswereobserved • Onlyonewas the beam gas ratesat 25ns, whichseems to be affected by the long-range. • Data wasverylittle, wehope to get more after LS1 … 

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