CMS Document 2941-v1

ECAL Spike Plots

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Nicolo Cartiglia
Updated by:
Nicolo Cartiglia
Document Created:
25 Aug 2010, 14:50
Contents Revised:
26 Aug 2010, 17:39
Metadata Revised:
16 Nov 2010, 10:02
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Images and documents relating to spokes observed in ECAL

In collision data we observe anomalous signals in ECAL, having the appearance of large energy deposits in a single crystal.

These signals are uniformly distributed and only in the barrel part of the calorimeter where the readout is by APD; they are not seen in the EE crystals readout by VPTs.
The rate of these anomalous signals is of order one per 103 minimum-bias events at c.m.s. of 900 GeV.

The origin of the signal is energy deposited by heavily ionizing particles in the avalanche photodiode.

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