For the low mass background systematic we first estimate the background contribution (or contamination factor) to the signal reigon.  That is we integrate our simulated background to discern t

We need to worry about a number of systematic effects that may change our measurement of A_LL.  These effects can be broadly separated into two groups: backgrounds and non background

The measurement of A_LL for inclusive neutral pion production is seen below along with statistical error bars and a systematic error band.  This asymmetry was calculated using a clas

The last piece of the invariant mass distribution is the combinatoric background.  This is the result of combining two non-daughter photons into a pion candidate.  Since each photon in an

The low mass background is the result of single photons being artifically split by the detector (specifically the SMD.)  The SMD fails in it's clustering algorithm and one photon is reconstruc

I treat the eta peak in a similar way as the pion peak.  I throw single etas, flat in Pt from 2 - 25, and reconstruct the two-photon invariant mass distribution for the results.  The thro

To study the pion peak section of the invariant mass distribution I looked at single pion simulations.  The pions were thrown with pt from 2 - 25 GeV/c flat and were reconstructed using the cu

 After all the pion candidates have been found and all the cuts applied, we need to extract the number of pions in each bin (in each spin state for A_LL.)  To do this we simply

Here I will detail the some general information about my analysis; topics that aren't substantial enough to warrant their own page but need to be documented.

The two-photon invariant mass is given (in the lab frame) by

M = Sqrt(2E₁E₂(1 - Cos(theta)))

The two-photon invariant mass distribution can be roughly broken up into four pieces, seen below^*.

Fig. 1

I am using the final polarization numbers from run 6, released by A. Bazilevsky to the spin group on December 4, 2007.  The files can be found below.

Below you will find the runlist I used for all of the studies leading up to a preliminary result.  For a more detailed look at how I arrived at this runlist please see my run

 Links for the 2006 Neutral Pion A_LL analysis

Background information

• Disk usage statistics 2008