HCAL operation since the last technical stop
Download
1 / 9

No dead cells (yet) - PowerPoint PPT Presentation


  • 86 Views
  • Uploaded on

HCAL operation since the last technical stop. No dead cells (yet) The integrated luminosity since the technical stop: 480.5 pb -1 . Gain drift and PMT rate effect are seen in HCAL, as usual. G ain corrections: at ~ -2% on average LED response of the 56 very central cells. Performed 4 times.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' No dead cells (yet) ' - kin


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

HCAL operation since the last technical stop

  • No dead cells (yet)

  • The integrated luminosity since the technical stop: 480.5 pb-1. Gain drift and PMT rate effect are seen in HCAL, as usual.

  • Gain corrections: at ~ -2% on average LED response of the 56 very central cells. Performed 4 times.

  • The L0Hadron rate variations within fill are seen. This is a consequence of HCAL PMT rate effect.

Yu. Guz 13/06/2012


HCAL HV correction

The reference LED amplitudes were chosen from the first high luminosity fill after the technical stop. The amplitudes used for correction, as well as the reference, were chosen taking into account the PMT rate effect: 1-2 h after the beginning of the fill,to let the PMT gain stabilize.

For the period between April and June technical stops, we use as a reference the saveset in fill 2583, CaloDAQCalib-114322-20120503T020756.root

The moment of change was determined from the average LED amplitude over 56 very central counters (10 ≤ ix ≤ 21, 13 ≤ iy ≤ 18) which contribute the most into the hadron trigger rate (shown by rectangle at the figure below). The threshold was arbitrarily set to 2-3% drop w.r.t. reference.

Yu. Guz 13/06/2012


HCAL HV correction

HV corrections

sum/sumref, 56 central cells

-2%

TS, source calibration

reference

four HV corrections since the technical stop:14-May, 23-May, 03-Jun, 12-Jun

the procedure works correctly

Yu. Guz 13/06/2012


L0hadron / L0muon 2012

In general, L0Hadron is reasonably stable.

Yu. Guz 13/06/2012


L0Hadron stability (Richard)

HCAL PMT heat up effect?: 2h

however, HCAL PMT rate effect leads to instability within fill

Yu. Guz 13/06/2012


HCAL HV update-II : L0Had / L0Mu (Regis Lefevre)

http://lblogbook.cern.ch/L0+Trigger/1411

Also seen by Regis before


HCAL rate effect 2012 (May 14-23)

>5%: 188 PMTs

>10%: 56 PMTs

The rate effect is present in the high luminosity data in many PMTs: 188 have >5%.

The nastiest case is when the rate effect is slow (one of such is unfortunately in the centre, I_18_15).

slow

fast

Yu. Guz 13/06/2012


HCAL rate effect 2012 (May 14-23) vs 2011

The magnitude of rate effect in the “bad” PMTs in 2012 is basically the same as (or even somewhat higher than) in 2011 (07-Sep – 05-Oct) (in spite of 2 times lower gain).

The PMTs looking improved are in fact those which were replaced during the shutdown (45 PMTs) or had contacts in signal path repaired (3 PMTs).

No new “bad” PMTs appeared.

It looks like the rate effect is an intrinsic feature of a PMT: HCAL has ~200 “special” unstable ones.

replaced in 2012

no new unstable ones

Then the L0Hadron behavior can be improved, by either rearranging of PMTs (moving the worst ones – to periphery) or replacing them by spares – a task for LS1.

Yu. Guz 13/06/2012


to compare: ECAL rate effect 2012 (May 14-23)

>5%: 34 PMTs

>10%: 3 PMTs

The distribution is similar to HCAL, but no tail at high values. Only 3 cells >10%, all suffer from contact instability, rate effect is moderate.

contact instability

rate effect

Yu. Guz 13/06/2012


ad