Star has collected data from the following collision energies

STAR has collected data from the following collision energies (in decreasing energy order) :

• STAR has collected data from the following collision energies (in decreasing energy order) :

• 200, 130, 62.4, 39, 19.6, 11.5, 9, 7.7 GeV

• This presentation aims to show the work-in-progress analysis of the 39 GeV data sample

• Spectra shapes and particle ratios help connect collected data to observables that are expected to change in such a phase transition

The TPC is a barrel shaped detector consisting of a gas-filled chamber, magnet providing a strong uniform magnetic field, and an electric field between the center and endplates

• The TPC is a barrel shaped detector consisting of a gas-filled chamber, magnet providing a strong uniform magnetic field, and an electric field between the center and endplates

• We use measurements of the ionization energy loss (dE/dx) and momentum to identify particles

From Min-Bias Trigger

• From Min-Bias Trigger

• |Vz| < 30 cm

• |Vr| < 2 cm

• 10 M events pass cuts

• Track-Quality Cuts

• |Dca| < 3 cm

• NHitFits > 25

• NHitFits/NHitPoss > 0.51

For overlap areas we rely on extrapolated centroid positions and yields

• For overlap areas we rely on extrapolated centroid positions and yields

• This is done independently in each particle-centered histogram, and across different rapidity bins

Cannot make a physics conclusions without corrections, which include:

• Cannot make a physics conclusions without corrections, which include:

• Single Particle Efficiency
• Energy Loss Correction
• Acceptance
• Proton Background

Our work-in-progress min-bias π+/π- ratio at 39 GeV is similar to results from 19 GeV & 200 GeV

• Our work-in-progress min-bias π+/π- ratio at 39 GeV is similar to results from 19 GeV & 200 GeV

• Plans for the future include:

• Efficiency Corrections
• Proton Background
• Energy Loss Corrections
• Investigate Rapidity Dependence
• K/Pi, p/Pi
• Integrated Yields & Ratios