EcalDPGResultsCMSDP2012027 < CMSPublic

---+ CMS-DP-2012/027 <br> ECAL response variations due to LHC irradiation



<strong>Abstract: </strong> Plots of the ECAL response to laser monitoring light in CMS during 2011 and 2012. The dependence vs time, eta and crystal radiation hardness are shown</br>

[[http://cdsweb.cern.ch/record/1491651?ln=en][CDS entry]]

[[http://cms.cern.ch/iCMS/jsp/openfile.jsp?type=DP&year=2012&files=DP2012_027.ppt][iCMS entry]]


%TABLE{ datavalign="middle" }%<br />
| *Figure * | *Caption* |
| [[%ATTACHURL%/laser_history_2011-12.pdf][pdf version]] <br/>%IMAGE{"%ATTACHURLPATH%/laser_history_2011-12.png" type="frame"  align="none"  size="500" desc=""}%  | __Relative response to laser light (440 nm) measured by the ECAL laser monitoring system, averaged over all crystals in bins of pseudorapidity, for the 2011 and 2012 data taking periods__ <br /> <br /> The response change observed in the ECAL channels is of the order of a few percent in the barrel, while it reaches up to 25% in the most forward endcap regions used for electron and photon reconstruction. The response change is up to 60% in channels closest to the beam pipe. These measurements are used to correct the physics data. <br /> <br /> This is an update of the plots appearing in CMS-DP-2012/007 and CMS-DP-2012/015, and includes measurements taken up to October 2012. The bottom plot shows the instantaneous LHC luminosity delivered during this time period.  |
| [[%ATTACHURL%/loss_vs_mustd.pdf][pdf version]] <br/>%IMAGE{"%ATTACHURLPATH%/loss_vs_mustd.png" type="frame"  align="none"  size="500" desc=""}%  | __Correlation between relative change of response from ECAL monitoring data, and the absorption coefficient, &#956;std, induced in crystals by a standard &#947; irradiation__ <br /> <br /> The relative change of response is computed between 6-September-2011 and 4-October&#8208;2011. The parameter &#956;std is measured from a standard &#947; irradiation, performed during crystal quality control measurements, prior to their installation in CMS. Crystals produced by Shanghai Institute of Ceramics (SIC), and installed in CMS in the eta range 2.4 < &#951; < 2.6, are plotted. <br /> <br /> The presence of a correlation proves that a fraction of the signal loss is due to a change in crystal transmission from ionizing radiation damage. <br /> <br /> The positive intercept of the correlation hints at the presence of a fraction of signal loss, uncorrelated with &#956;std, which could be caused by other sources, like losses in VPT response or cumulative losses from hadron&#8208;specific changes in crystal transmission. |

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
pdf	laser_history_2011-12.pdf	r1	manage	2050.8 K	2013-07-11 - 17:28	ToyokoOrimoto
png	laser_history_2011-12.png	r1	manage	123.8 K	2013-07-11 - 17:28	ToyokoOrimoto
pdf	loss_vs_mustd.pdf	r1	manage	47.0 K	2013-07-11 - 17:29	ToyokoOrimoto
png	loss_vs_mustd.png	r1	manage	19.9 K	2013-07-11 - 17:29	ToyokoOrimoto

This topic: CMSPublic > PhysicsResults > EcalDPGResults > EcalDPGResultsCMSDP2012027
Topic revision: r1 - 2013-07-11 - ToyokoOrimoto

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