| 3 |
|
The first step of the HCAL calibration with collisions data is to equalize the response in |
| 4 |
|
$\phi$ for each $\eta$ ring. The procedure takes advantage of the azimuthal |
| 5 |
|
symmetry of the detector and the corresponding $\phi$-symmetric energy |
| 6 |
< |
deposition from minimum bias (MinBias) events. |
| 7 |
< |
The intercalibration is |
| 6 |
> |
deposition from events triggered as Minimum bias and photon triggers. |
| 7 |
> |
These two different data samples supposed different calibration procedures to be performed. |
| 8 |
> |
\begin{itemize} |
| 9 |
> |
\item The intercalibration with photon triggered events is performed via equalizing the rate of readout energies |
| 10 |
> |
above some threshold |
| 11 |
> |
|
| 12 |
> |
\item Method of moments: The intercalibration with minbias events is |
| 13 |
|
performed by comparing the average energy deposit in a calorimeter cell |
| 14 |
|
to the mean of the average energy distributions in the entire $\eta$-ring |
| 15 |
|
(cells with $i\eta$=const). |
| 19 |
|
The conditions are more favorable in HF where the noise is |
| 20 |
|
comparable or even lower then the signal (about a hundred~MeV in HF at $i\eta$=30, and a few hundreds~MeV |
| 21 |
|
at $i\eta$=40). |
| 22 |
+ |
\end{itemize} |
| 23 |
|
|
| 24 |
< |
\subsection{General description} |
| 24 |
> |
\subsection{Method of moments} |
| 25 |
|
|
| 26 |
|
%Correction of the azimuthal symmetry is the relative correction, which set |
| 27 |
|
%gains such, that energy deposition from the signal from the uniform event |
| 103 |
|
estimated energy in each channel in both the signal and noise time windows, along with |
| 104 |
|
event trigger information. |
| 105 |
|
For azimuthal symmetry we select all triggers except the zero-bias one. |
| 106 |
< |
The AlCaReco data are directed to the CERN analysis Facility (CAF) where further analysis and extraction of correction coefficients are performed. |
| 106 |
> |
The AlCaReco data are directed to the CERN analysis Facility (CAF) where further analysis and extraction of |
| 107 |
> |
correction coefficients are performed. |
| 108 |
|
The workflow was tested during several exercises starting from 2006 year. |
| 109 |
|
|
| 110 |
|
|
| 279 |
|
\end{center} |
| 280 |
|
\end{figure} |
| 281 |
|
|
| 282 |
< |
\subsection{Summary for Calibrations with MinBias Events} |
| 282 |
> |
\subsection{Summary for Monte-Carlo studies of Calibrations with MinBias Events} |
| 283 |
|
|
| 284 |
|
A set of triggers have been investigated with 10 TeV MinBias sample: |
| 285 |
|
ZB trigger provides too low energy deposition in HB/HE and, thus, |
| 299 |
|
The calibration of HF down to 2\% level can be performed with 900 GeV |
| 300 |
|
sample assuming that we get ~200 Kevents with EG2 trigger. |
| 301 |
|
|
| 302 |
+ |
\subsection{Calibration of data} |
| 303 |
+ |
|
| 304 |
+ |
A set of data was taken during 2010 and 2011 years in NZS stream for beams with $\sqrt{s}=7$~TeV. 3 millions of pp events collected in 2010 |
| 305 |
+ |
(RunA and RunB up to run 148058) allow to calibrate HF/HB/HE calorimeters. Only good lumisections according CMS certification were taken. |
| 306 |
+ |
Technical bit selection (BPTX plus beam halo veto) was switched on. |
| 307 |
+ |
|
| 308 |
+ |
The calibration coefficients obtained with mean and variances for $i\eta$ = 35 (HF), 21 (HE) and 10 (HB) |
| 309 |
+ |
are presented in Figs.~\ref{fig_datapp2010_1}-\ref{fig_datapp2010_3}. |
| 310 |
+ |
|
| 311 |
+ |
\begin{figure}[!Hhtb] |
| 312 |
+ |
\begin{center} |
| 313 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/h_vminc_10.eps} |
| 314 |
+ |
\caption{Correction coefficients calculated using mean (black points) and variance (redpoints) of reconstructed energy distribution in tower |
| 315 |
+ |
for $i\eta$=10.} |
| 316 |
+ |
\label{fig_datapp2010_1} |
| 317 |
+ |
\end{center} |
| 318 |
+ |
\end{figure} |
| 319 |
+ |
|
| 320 |
+ |
\begin{figure}[!Hhtb] |
| 321 |
+ |
\begin{center} |
| 322 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/h_vminc_21.eps} |
| 323 |
+ |
\caption{Correction coefficients calculated using mean (black points) and variance (redpoints) of reconstructed energy distribution in tower |
| 324 |
+ |
for $i\eta$=21.} |
| 325 |
+ |
\label{fig_datapp2010_2} |
| 326 |
+ |
\end{center} |
| 327 |
+ |
\end{figure} |
| 328 |
+ |
|
| 329 |
+ |
\begin{figure}[!Hhtb] |
| 330 |
+ |
\begin{center} |
| 331 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/h_vminc_22.eps} |
| 332 |
+ |
\caption{Correction coefficients calculated using mean (black points) and variance (redpoints) of reconstructed energy distribution in tower |
| 333 |
+ |
for $i\eta$=21.} |
| 334 |
+ |
\label{fig_datapp2010_3} |
| 335 |
+ |
\end{center} |
| 336 |
+ |
\end{figure} |
| 337 |
+ |
|
| 338 |
+ |
Heavy ion collisions were registered in Novemeber 2010. The energy deposition in readouts in barrel is 10 times higher for AA events |
| 339 |
+ |
then for pp with 2.4 of pileup average. The comparison of mean pp and AA vs $\eta$ and variance of pp and AA vs $\eta$ is presented in |
| 340 |
+ |
Fig.~\ref{fig_mean_var_pp_AA}. |
| 341 |
+ |
|
| 342 |
+ |
\begin{figure}[!Hhtb] |
| 343 |
+ |
\begin{center} |
| 344 |
+ |
\includegraphics*[width=0.49\textwidth]{figs/AzimMoments/mean_vs_eta.eps} |
| 345 |
+ |
\includegraphics*[width=0.49\textwidth]{figs/AzimMoments/var_vs_eta.eps} |
| 346 |
+ |
\caption{The mean energy deposition (left plot) and variance (right plot) per readout averaged over eta ring as a function of $i\eta$ for |
| 347 |
+ |
pp events (red points) and AA events (black points).} |
| 348 |
+ |
\label{fig_mean_var_pp_AA} |
| 349 |
+ |
\end{center} |
| 350 |
+ |
\end{figure} |
| 351 |
+ |
|
| 352 |
+ |
The variance of noise is shown in Fig.~\ref{fig_var_noise_pp_AA}. Noise is stable in time and the value of signal increases 10 times in AA |
| 353 |
+ |
events in comparison with pp. Signal to background ratio improved and less statistics is needed to achieve the same level of accuracy. |
| 354 |
+ |
|
| 355 |
+ |
\begin{figure}[!Hhtb] |
| 356 |
+ |
\begin{center} |
| 357 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/varnoise_vs_eta.eps} |
| 358 |
+ |
\caption{The variance of noise as a function of $i\eta$ for |
| 359 |
+ |
pp events (red points) and AA events (black points).} |
| 360 |
+ |
\label{fig_datapp2010_3} |
| 361 |
+ |
\end{center} |
| 362 |
+ |
\end{figure} |
| 363 |
+ |
|
| 364 |
+ |
Corrections got with AA events were used for the cross-check of the corrections got at the end of pp run. |
| 365 |
+ |
The comparison of the coefficients obtained with pp and AA using variances is shown in |
| 366 |
+ |
Figs.~\ref{fig_datappAA2010_1}-\ref{fig_datappAA2010_2}. |
| 367 |
+ |
|
| 368 |
+ |
\begin{figure}[!Hhtb] |
| 369 |
+ |
\begin{center} |
| 370 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/hmin_d1_hbhe_ppAA_21.eps} |
| 371 |
+ |
\caption{Correction coefficients calculated using variance of reconstructed energy distribution in tower |
| 372 |
+ |
for $i\eta$=10 for pp events (black points) and AA events (red points).} |
| 373 |
+ |
\label{fig_datappAA2010_1} |
| 374 |
+ |
\end{center} |
| 375 |
+ |
\end{figure} |
| 376 |
+ |
|
| 377 |
+ |
\begin{figure}[!Hhtb] |
| 378 |
+ |
\begin{center} |
| 379 |
+ |
\includegraphics*[width=10cm]{figs/AzimMoments/hmin_d1_hbhe_ppAA_21.eps} |
| 380 |
+ |
\caption{Correction coefficients calculated using mean (black points) and variance (redpoints) of reconstructed energy distribution in tower |
| 381 |
+ |
for $i\eta$=21 for pp events (black points) and AA events (red points).} |
| 382 |
+ |
\label{fig_datappAA2010_2} |
| 383 |
+ |
\end{center} |
| 384 |
+ |
\end{figure} |
| 385 |
+ |
|
| 386 |
+ |
|
| 387 |
+ |
|
