CMS experiment

Azimuthal anisotripy in HIC with CMS Tracker

********************************************

Draft 1

Date: 12 Jan 2007 From: DavidKrofcheck

Hi Gyulnara!

This is a great start for studying elliptic flow at CMS. Good work!

There are some typos and english problems which I can fix if I can access the tex file.

A couple of questions come to my mind. First, in Section 3.1 there are reconstructed tracks at a fixed impact parameter (b=9 fm). Then in Section 3.2 are another 1000 minimum bias events are generated. Did I read that correctly? If so, then do you then need to show plots (essentially Fig 3 and Fig 4)) again for these minimum bias events? Was there some impact parameter selection for the minimum bias events ?

Response

We have 1000 events in each centrality bin - so 12 bins x 2 histograms = 24 plots. This amount seems too large, moreover these events are not really used for subsequent analysis, but just illustrate the dependence of accuracy of event plane determination on centrality.

In our tex we change:

To illustrate the dependence of accuracy of event plane determination on event centrality, a set of 1000 HYDJET \rm{Pb+Pb} events at generator level for each centrality bin covering the range of impact parameters from $b=0$ to $b=2R_A$ ($R_A$ is a nuclear radius) without and with jet quenching have been generated.

In Section 4 it is mentioned that, "Also we calculate V2 coefficient from fitting." The meaning is less clear to me., i.e. Does "fitting" mean V2 was determined for each reconstructed event using Eq 2, then you "fit" the distribution of all of the V2's (to get Fig 7(V2 from Eq.3) and Figure 10(V2 from Eq. 4))?? Sorry, I am just confused.

Response

In our tex we change:

Also we calculate $v_2$ coefficients from fitting the $dN/d\varphi$-distribution in each event by formula (\ref{f.2}) with the following free parameters $N_0$, $v_2$ and $\Psi_R$.

Distribution of $v_2$-parameters, extracted from fitting of $dN/d\varphi$-distribution in each event by formula (\ref{f.2}) is shown in Fig. 10.

Everybody, Best wishes for a Happy New year, and a slightly late Merry Christmas!

Response

Thanks a lot for corrections.