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C+C pions rapidity fits with temperature formula

y = C * T^3 * ( (m0/T)^2 + 2*m0/(T*cosh(y*y_cm)) + 2/(cosh(y*y_cm)**2) ) *exp(-m0*cosh(y*y_cm)/T)
where y = (y_lab-y_cm)/y_cm
with 2 parameters C and T.
Constants: m0=139.57, y_cm=0.677 for 1 GeV and 0.907 for 2 GeV
(e.g. S Sadovski PhD page 78 eq 7.17)

First check of the formula on the "ideal" PLUTO distribution for 1 GeV with T=58 MeV and A_2=0 (and blast=0):

  • PLUTO right: fit within measured range, left: fit in full range - both work well, see parameter p1 == T
    PLUTO left: fit within measured range, right: fit in full range

Now fit of PLUTO distribution for 1 GeV with T=58 MeV and anisotropy A_2=0.34:

  • PLUTO right: fit within measured range, left: fit in full range: in full range the fitted slope changed by 16 MeV, chi^2 high. In measured range the
T slope cannot be recovered.
PLUTO right: fit within measured range, left: fit in full range

Now exp. data fit (together with fit of UrQMD data within measured range and full range) for CC at 1 GeV and 2 GeV. Results are summarized below in the table:

  • C+C 1 AGeV:
    C+C 1 AGeV

  • C+C 2 AGeV:
    C+C 2 AGeV

C+C 1 AGeV
  exp.   UrQMD   UrQMD  
      exp. range   full range fit  
  T chi2/NDF T chi2/NDF T chi2/NDF
pi+ 119+-24 2.7/20 1530+-2040 4256/20 172.4+-0.5 16600/39
pi- 114+-22 4.6/20 1634+-2057 6072/20 184.0+-0.6 23400/39

C+C 2 AGeV
  exp.   UrQMD   UrQMD  
      exp. range   full range fit  
  T chi2/NDF T chi2/NDF T chi2/NDF
pi+ 2900+-111 31/13 2600+-2050 7280/13 315.4+-1.4 49200/39
pi- 2677+-53 26/13 2393+-5 6449/13 310.0+-1.3 48300/39

-- PavelTlusty - 28 May 2008
Topic attachments
I Attachment Action Size Date Who Comment
c1c_rapfit_expsim.gifgif c1c_rapfit_expsim.gif manage 31.5 K 28 May 2008 - 11:59 PavelTlusty C+C 1 AGeV
c1c_rapfit_pluto_T_58_A2_0.34.gifgif c1c_rapfit_pluto_T_58_A2_0.34.gif manage 18.4 K 28 May 2008 - 11:53 PavelTlusty PLUTO right: fit within measured range, left: fit in full range
c1c_rapfit_pluto_T_58_A2_0.gifgif c1c_rapfit_pluto_T_58_A2_0.gif manage 18.5 K 28 May 2008 - 11:49 PavelTlusty PLUTO left: fit within measured range, right: fit in full range
c2c_rapfit_expsim.gifgif c2c_rapfit_expsim.gif manage 32.4 K 28 May 2008 - 12:00 PavelTlusty C+C 2 AGeV
Topic revision: r2 - 28 May 2008, PavelTlusty
 
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