# A Resolutions of ATLAS Detectors

1. Apr 11, 2016

### ChrisVer

Hi,
I was looking for ATLAS detector parts resolutions (momentum for Inner Detector and Energy for the CAL systems).
Does anyone have a nice reference?
So far I found something like this for the ID:
$\sigma_{1/p_T} = 0.34 \text{TeV}^{-1} \Big(1 \oplus \frac{44 \text{GeV}}{p_T} \Big)$
With $\oplus$ meaning that the two terms are added in quadrature and then the square root is taken.
However this formula was from Run1 and before the installation of the B-Layer.
Has the last altered this expression?

Similarily for the ECAL:
$\frac{\sigma_E}{E(\text{GeV})} = \frac{a}{\sqrt{E(\text{GeV})}} \oplus b$
$a_{\text{design}}=10 \%$
$b_{\text{design}}=0.7 \%$
or from tests on e, μ and pions:
$a_{\text{exper}}=10.7 \%$
$b_{\text{exper}}=0.5 \%$
(http://iopscience.iop.org/article/10.1088/1748-0221/3/08/S08003/meta)

Do you know if they have changed (ref)?
I don't think that the dependencies will be changed (1/p or sqrt(1/E) ) but the numbers in front probably have.

Thanks.

2. Apr 11, 2016

### Staff: Mentor

You can simply go through the list of things ATLAS published, e. g. this page for the performance of the inner detector tracking. Found with google: "atlas inner detector momentum resolution".