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Re: EMC resolution [message #15871 is a reply to message #15567] Thu, 13 February 2014 15:16 Go to previous messageGo to previous message
binsong is currently offline  binsong
Messages: 10
Registered: December 2011
occasional visitor
From: *in2p3.fr
Dear all,

now the problem is clear. it is due to the nonuniformity.

To obtain a realistic resolution (validated by the PROTO60 results),
simulations must be done using following parameters in all.par:

Use_nonuniformity:1
Use-Shaped_noise 0

The first flag needs to be set to 1 to take into account the observed
non linearity of the light yield
in the barrel EMC crystals as a function of the interaction depth.
The effect is an increase of the sigma of a Nivosibirsk fit from
1.6 (Use_nonuniformity:0 ) to 2.5 % (with Use_nonuniformity:1) for
photons at 1 GeV with a flat distribution in theta from 30 to
130 deg.

With the second flag set to 0, a more precise description of the
electronic noise is obtained, while faster but less accurate results are
obtained with the flag set to 1. The effect is an increase of the
sigma of a Novosibirsk fit from
2.2 (Use-Shaped_noise 1) to 2.5 % (Use-Shaped_noise 0) for a photon
at 1 GeV

Before end of november 2013, the standard parameters were
"Use_nonuniformity 0" and "Use-Shaped_noise 1", leading to a too
optimistic resolution, by about a factor 2. Now, the standard setting is
"Use_nonuniformity 1" and "Use-Shaped_noise 0")

The raw energy includes both effects of the non-uniformity and of the
electronic noise. The cluster calibrated energy is deduced using
calibration
parameters adjusted as a function of theta and energy to reproduce the
pi0 mass.
By default, the calibration parameter file is the one corresponding to
Use_nonuniformity:1 and "Use-Shaped_noise 0".

The two attached figures are the results for photon with the new version of pandaroot.
index.php?t=getfile&id=7696&private=0

[Updated on: Thu, 13 February 2014 16:54]

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