The STAR experiment

It was reported that the tuning of the scale factor (Normalization Factor in TRS) was giving different results in SL08c library at PDSF and RCF (see

 Bernd has asked that I put the details of my analysis into a static webpage (not a blog post like this one), but in order to get things in order in my head, this is where I'm starting.

 Brief introduction to the code

 Using the yield formula I showed at the last meeting, I can now generate yields for the xs data that have better-contained error bars and are also far more accurate when the signal-to-backgro

This page summarizes the effect of each major cut in the 2006 jet+charged pion analysis. Each plot is obtained by applying all other applicable analysis cuts except the one being illustrated.

Figure 1: Black is TPC z-vertex for all BJP1-triggered events, Green is the TPC z-vertex distribution for events in BBC timebins 6-9, and Red is the TPC z-vertex distributions for all charged pion tracks (inclusive, no trigger jet requirement).

It appears at first that the vz distribution of good tracks is broader than the BBC 6-9 distribution, but that’s not actually the case. Here’s the ratio of the red and green histograms from the above plot:

Figure 1b

The following histograms use positively charged pions from any spin state. Black lines are inclusive π+ passing all cuts except the one being shown, green lines are leading π+ opposite a trigger jet, and the filled green histogram shows the π+ accepted for the asymmetry analysis.

Figure 2: |η| < 1.0

Figure 3: |dcaG| < 1.0

Figure 4: nHitsFit > 25

Figure 5: nσ(π). It’s not possible to read off the efficiency from this histo because I actually use a time-dependent cut window based on the results of fill-by-fill fits to the nσ(π) distributions. Ideal world cut shown is nσ(π) [-1,2]

Here’s the ratio of the green and black histograms from that plot. The away-side spectrum has a relative lack of electrons but an increase in the p/K contamination:

Figure 5b

I should also add some more plots here documenting the cuts on jet pT, detector η, and N.E.F.

Asymmetries are defined as (Y,B):