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Update on background observations during HI in ALICE

A. Alici (INFN, Bologna), A. Di Mauro (CERN) LBS, 16/04/12. Update on background observations during HI in ALICE. Follow up of background during fills with ions.

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Update on background observations during HI in ALICE

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  1. A. Alici (INFN, Bologna), A. Di Mauro (CERN) LBS, 16/04/12 Update on background observations during HI in ALICE

  2. Follow up of background during fills with ions • As pointed out in LBS#30 (21/11/11), vacuum was generally good, however some correlated fluctuations have been observed in muon trigger and ZDC rates, indicating beam-1 (A- side) related background 0MSL (single muon1 GeV/c standalone) (screenshots of DCS panels) ALICE background, LBS #35

  3. Run167921FILL 2294 Min. bias, central and semi-central trigger rateisquite uniform intime, while structures are visibleinthe muon triggers (B1 direction selectivity). Strong timecorrelation between backgroundevents andspikesintheZDC ALICE total instantaneous luminosity byZDC ALICE background, LBS #35

  4. FILL 2294 Strong correlation with losses in TCTH-B1 ALICE background, LBS #35

  5. Other BLMs in FILL 2294 Only BLM_TCTH.4L2.B1 shows increase in losses towards the end of the fill ALICE background, LBS #35

  6. BLM on TCTH 4L2 and 4R2 in FILL 2294 Losses only on L side ALICE background, LBS #35

  7. RUN167921 FILL 2294 O I B1 Background events mapping in muon trigger detector, losses in H plane, I side ALICE background, LBS #35

  8. Further observations • A detailed analysis of all fills has shown that fluctuations in ZDC count rates are always correlated to losses on TCTH, which generally increases towards the end of the fill. ALICE background, LBS #35

  9. FILL 2319 ALICE background, LBS #35

  10. V0BG/All for different muon triggers in red: runs at end of fill 167921 MUSHPB 170208 169981 170390 168325 Muon unlike Muon like ALICE background, LBS #35

  11. Acc/All and V0BG/All ratios for muon trigger classes Run 170390 BB BG ALICE background, LBS #35

  12. Summary • TCT background has been observed during HI fills affecting ZDC-A (downstream TCTH.4L2) and muon trigger rates, MB and centrality triggers not affected • Diagnostic on beam quality in progress, however so far no anomalies have been detected using BWSand BSCRTL ALICE background, LBS #35

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