p_lab plots for pi+ from C+C at 1 and 2A GeV are compared to pi+ from KAOS.
TAPS data points are from Ch. Sturm (published in his thesis, page 81, Fig.4.7), and show d(sigma)/dp_lab at 44+-4 and 54+-4 deg for 1A GeV, and at 32+-4 deg. and 40+-4deg. for 2A GeV (region close to midrapidity). The HADES points are re-calculated from multiplicity to cross section assuming total cross section 950 mb, and corrected to minimum bias by a ratio of number of participants 6./8.61 and 6./8.38 for 1 and 2 GeV, respectively.
2 figures show the comparison for 1 and 2 GeV

  • c1c:

  • c2c:

The same figures in the linear scale are also attached. For 1 GeV data we have almost perfect agreement, for 2 GeV our data are systematically lower than the KAOS points at low momenta region, just outside the error bars (about 10% difference).
There can be problem with upper range in momenta of our data. When pi/p ratio is low, we do not separate protons and pi+ already at momenta below 1000 MeV/c. For 1 GeV I already cut points with p_lab above 775 and 875 Me/c for 44 and 54 degrees, respectively. For 2 GeV, it probably should be done for p_lab > 900 MeV/c for the 40 deg. data.

Comparison of the cross sections within KAOS acceptance (p_lab > 175 MeV/c):
                  HADES              KAOS    p_lab>175MeV/c
1GeV 44 deg        46+-3+-3         46+-2
     54            29+-1.5+-2       29+-2

                  HADES              KAOS
2GeV 32 deg        173+-9+-12      185+-5
     40            120+-6+-9       129+-4


Errors of our data: 1st error is a 5% error of the efficiency correction, the 2nd is a 7% error of the correction to min. bias.

-- PavelTlusty - 02 Dec 2008

  • c1c liny:
    c1c liny

  • c2c liny:
    c2c liny
Topic revision: r4 - 2008-12-05, PavelTlusty
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