The STAR experiment

See attached version 1 of the Analysis Meeting talk

Background:  Ahmed posted some studies of the BSMD in Run 7 indicating that the ADC dynamic range is limited.  Pibero and Willie showed a dramatic band structure of the raw ADCs in the 2006 pp, and people wondered how far back this structure existed.  Here is the data from 2005.

What's being plotted:

• 2005 pp data
• BSMDE
• zero-suppressed at (adc-ped) < 1.5*rms
• NOT pedestal-subtracted
• restricted to status==1
• ~4000 files from throughout Run 5
• strip softId on x-axis -- each plot is another 1000 strips

And finally, here's a projection of strips 1-150:

Clearly, the band structure was there as well.

Update:  Renee mentioned that 4500-4600 look a little cleaner than the rest.  Here are projections for 4500-4590 and 4500-4650.  The band structure doesn't disappear, but the slope of the exponential fall-off is steeper so fewer counts end up in the screwy 500+ regime.  Here are the results of fits to the region 100 - 150:

0001-0150:  slope = -0.0105
4500-4650:  slope = -0.0130
4500-4590:  slope = -0.0150

See also:  2005 BSMD zero-suppressed ADCs (minbias triggers)

Motivation:  We see a strange band structure in raw ADC vs. softId plots for the BSMD.  To date these plots have been generated by integrating over all triggers.  The idea here is to restrict to minimum-bias triggers to see if some of these bumps around ADC >~ 500 could be due to trigger turn-on curves.

Results:  At first glance, the trigger doesn't seem to be causing much of the bump.  On the left is a projection of raw ADC for BSMDE strips 1-150 using all triggers from 2005 pp data.  On the right is the same plot for MB-only, rebinned to deal with the limited statistics.  The MB plot was generated from a separate runlist with roughly 3x more statistics than the trigger-integrated plot.

Stats aren't great, but I think one can pick out the three bumps at ~500, ~570, and ~610, plus the ending spikes at ~710.  Looks like it's not the trigger.

References: 
2005 BSMD zero-suppressed ADCs
 

Updated version.

Abstract:

This is a study of 2005 data conducted in March 2006.  Ported to Drupal from MIT Athena in October 2007

Goal: Quantify the relationship between the z-vertex position and the bbc timebin for each event.

Procedure: Plot z-vertex as a function of trigger and bbc timebin. Also, plot distributions of bbc timebins for each run to examine stability. Exclude runs<=6119039 as a result. Fit each vertex distribution with a gaussian and extract mean, sigma.  Plots are linked at the bottom of the page.  See in particular page 8 of run_plots.pdf, which shows the change from 8 bit to 4 bit onlineTimeDifference values.

Timebin 12 had zero counts for each trigger. Summaries of the means and sigmas:

Conclusions: Hank started the timebin lookup table on day 119, so this explains the continuous distributions from earlier runs. In theory one could just use integer division by 32 to get binned results before this date, but it would be good to make sure that no other changes were made; e.g., it looks like the distributions are also tighter before day 119.  Examining the vertex distributions of the different timebins suggests that using timebins {6,7,8,9} corresponds roughly to a 60 cm vertex cut. A given timebin in this range has a resolution of 30-45 cm.

This is a study of 2005 data conducted in March 2006.  Ported to Drupal from MIT Athena in October 2007

eL_asymmetries.pdf
phi_asymmetries.pdf

This is a study of 2005 data conducted in May 2006.  Ported to Drupal from MIT Athena in October 2007

Hi jetters. Mike asked me to plot the charged track / pion asymmetries in a little more detail. The structure is the same as before; each column is a trigger, and the four rows are pi+/Yellow, pi+/Blue, pi-/Yellow, pi-/Blue. I've split up the high pt pion sample (2< pT < 12 GeV) and plotted single-spin asymmetries for timebins 7,8, and 9 separately versus pT and phi.  The plots and summaries are linked at the bottom of the page.

2 sigma effects are highlighted in yellow, 3 sigma in red. There are no 3 sigma asymmetries in the separate samples, although pi-/B/JP1 is 3 sigma above zero in the combined sample. Here's a table of all effects over 2 sigma:

If you compare these results with the ones I had posted back in March (First Look at Single-spin Asymmetries), you'll notice the asymmetries have moved around a bit for the combined sample. The dominant effect there was the restriction to the new version of Jim's golden run list. The list I had been using before had at least two runs with spotty timebin info for board 5; see e.g.,

http://www.star.bnl.gov/HyperNews-star/protected/get/jetfinding/355/1/1/1.html

and ensuing discussion. I'm in the process of plotting asymmetries for charged track below 2 GeV in 200 MeV pT bins and will post those results here when I have them.

Test Blog Jan

Problem:

    Our second attempt at utilizing the SMD information for direct photon/background discrimination this time using the popular variable