pion multiplicities for C+C 1 and 2 A GeV, status 10.10.07

Conditions: LVL1 trigger, efficiency and acceptance corrected ("4pi")

Extrapolation from HADES acceptance (in rapidity) to full space:

old - taking number of pions within acceptance (theta vs momentum), and extrapolation done using UrQMD pi yield within the same acceptance and (known) total yield (Jan07)

new: - within HADES acceptance in rapidity: extrapolating p_t distributions (in rapidity bins) via fitting by 2 slope exponential, see http://hades-wiki.gsi.de/cgi-bin/view/SimAna/Version11 Resulted rapidity distributions (exp. data as average from all sectors) are shown in figures below.

Then extrapolating to all rapidities
1) using UrQMD
2) using Pluto simulation with exp. slopes and A2 parameters.

pi multiplicities, LVL1, acceptance corrected
old (Jan07) new(UrQMD) new(Pluto)

1 GeV 0.538 0.525 0.473
2 GeV 1.16 1.29 1.20

(multiplicity of pi for C2C from PLUTO corrected 15.10.07 from 1.14 to 1.20, the normalization factor was wrong by mistake)

There is about ~10% difference between 2 extrapolation methods. "Goodness" of extrapolation can be judged from following figures showing rapidity distribution: blue - data, red - urqmd, black - PLUTO. (PLUTO shown in arbitrary scale). Open symbols in fig. for C1C show points mirrored from forward rapidity.

• C1C:
  

• C2C:
  

Below is comparison of p_t distribution of pi- (within HADES rapidity acceptance) from data, UrQMD and PLUTO:

• c1c pt in HADES rapidity acceptance:
  

• c2c pt in HADES rapidity acceptance:
  

• C1C PLUTO rapidity distribution for various slopes and A2: maximum deviation of the correction factor 3%
  

• C2C PLUTO rapidity distribution for various slopes and A2: maximum deviation of the correction factor 2%
  

Final detailed table (15.10.07): normalization via UrQMD and PLUTO:

yields after pt extrapolation, average 5 sectors:

pi yields from rapidity histos: (pt extrapolated)
C1C rapidity range -1.1 <= y0 <= 1.1 (symmetrized from forward rapidity)
C2C rapidity range -0.8 <= y0 <= 0.7

C1C		exp		UrQMD		UrQMD(4pi)		f(UrQMD)		4pi exp UrQMD		f(PLUTO)		4pi exp PLUTO
pi+		0.360		0.357		0.506		1.418		0.510		1.281		0.461
pi-		0.379		0.367		0.523		1.426		0.540		1.281		0.485
average										0.525				0.473

C2C		exp		UrQMD		UrQMD(4pi)		f(UrQMD)		4pi exp UrQMD		f(PLUTO)		4pi exp PLUTO
pi+		0.759		0.699		1.16		1.665		1.26		1.559		1.18
pi-		0.783		0.712		1.18		1.664		1.31		1.559		1.22
average										1.29				1.20

-- PavelTlusty - 15 Oct 2007