1. New Strangeness Results from HADES
Laura Fabbietti for the HADES Collaboration  K+ K-  K0
V.Kandinskij: ‚Nuclear Reaction‘
Strange Quark Matter 2008, Beijing

2. Strange Quark Matter 2008, Beijing
Prologue:
Strange particle Production at SIS energies (1-2AGeV). What is missing to complete the picture?
Hadron Identification with the HADES Spectrometer in Ar+KCl 1.75 AGeV 

K-,K+
and /K- Ratio
Epilogue
Anticipations..
Strange Quark Matter 2008, Beijing

3. Strange Quark Matter 2008, Beijing
K+ Flow at SIS
Suggests the existence of a repulsive K+-N potential
Y. Shin et al. Phys. Rev Lett. 81 (1998)
P.Crochet et al. Phys. Lett. B 486 (2000) 6.
Out of Plane Flow of K+
Sideward Flow of K+
Pot
No Pot.
RBUU:G.Q.Li et al. Phys. Lett. B 381 (1996) 17.
RBBU: E. Bratkovskaya et al. Nucl. Phys. A622 (1997) 593.
What about K-flow?
HADES is still missing an Event plane reconstruction..(upgrade)
Strange Quark Matter 2008, Beijing

4. Strange Quark Matter 2008, Beijing
Testing EOS
Au+Au
C+C
C. Sturm et al. Phys.Rev.Lett. 86 (2001) 39-42
A. Foerster et al., Phys. Rev. C
Soft or Hard equation of state?
K+, due their rather long (5 fm) mean free path are suitable to measure the compressibility of nuclear Matter.
The ratio of the Au+Au to C+C K+ Yield favours a soft equation of state with KN ~ 200 MeV
Strange Quark Matter 2008, Beijing

5. Strange Quark Matter 2008, Beijing
New Foundings about
-induced reactions
M. L. Benabderrahmane et al. arXiv: v4
It is here clearly visible that the low momentum range of the distribution experiences more strongly the effect of the potential... If any...
Strange Quark Matter 2008, Beijing

6. Strange Quark Matter 2008, Beijing
Origin of the K-
A. Foerster et al., Phys. Rev. C
Since K+and K- yields scale similarly as a function of Apart
+ TK+>TK-
Strangeness Exchange is thought to be the dominating Mechanism for the production of K-in heavy ion collisions....
Is that true?
Strange Quark Matter 2008, Beijing

7. The HADES Spectrometer
Ar+KCl Data Sample
Data taken during the campaign in 2005 at GSI
AGeV
6.9*108 events used for the analysis
Detector Components
22 Multiwire Driftchambers for Track Reconstruction
2 Time of Flight (TOF) Walls for velocity measurement and evalution of the charge particle multiplicity.
dE/dx information from TOF and MDC Detectors.
preSHOWER/RICH for Lepton Trigger and Identification
Superconducting Toroidal magnetic Field for tracks bending
Strange Quark Matter 2008, Beijing

8. Strange Quark Matter 2008, Beijing
HADES Capabilities
Dileptons → π0/η over a large pT range ( MeV/c)
→ light meson resonances (φ, ω, η) via both electromagnetic and hadronic decays
Single charged hadrons ( p,d, π+/-, K+/-,)
Correlation analysis for the identification of: , KS0, 
Strange Quark Matter 2008, Beijing

9. Strange Quark Matter 2008, Beijing
Centrality Selection
P.Tlusty
centrality selection by the LVL1 trigger
(UrQMD Simulation)
 35% Most Central Collisions
<b> (fm)
<Npart.>
min. bias
5.83
19.25
LVL1
3.54
38.5
Strange Quark Matter 2008, Beijing

10. Strange Quark Matter 2008, Beijing
Pion Spectra
P. Tlusty
Large Acceptance:
Min PT: 50 MeV/c for 
Min PT: 100 MeV/c for 
HADES:
N/ Apart. = 0.088±0.013
(+ and  averaged)
(UrQMD gives 0.100)
FOPI:
0 from TAPS:Phys. Rev. C 67, (2003)
Nπ/Apart = AGeV)
W. Reisdorf et al., Nucl. Phys. A (2007)
Strange Quark Matter 2008, Beijing

11. Pions: mT Distributions
A. Schmah
Strange Quark Matter 2008, Beijing

12. Pions: mT Distributions
IQMD: C. Hartnack, J. Aichelin
Centrality selection: hard cut on b<6 fm in the IQMD
<b>= 3.530.2 fm
Agreement with IQMD Calculation within 15%
PRELIMINARY
Strange Quark Matter 2008, Beijing

13. Strange Quark Matter 2008, Beijing
Reconstruction
A. Schmah
Invariant Mass
Phase Space Distribution
Numbers:
Reconstructed from the decay Channel
<S/B> =1.0
MeV/c2 c
Strange Quark Matter 2008, Beijing

14. Strange Quark Matter 2008, Beijing
Reconstruction
A. Schmah
Invariant Mass
Phase Space Distribution
reconstructed Hyperons
in the Decay Channel
<S/B>
MeV/c2
Numbers:
Strange Quark Matter 2008, Beijing

15. Strange Quark Matter 2008, Beijing
MT Spectra for and
PRELIMINARY
Boltzmann-Fit:
Rapidity Density Function:
Strange Quark Matter 2008, Beijing

16. Potential or No Potential?
IQMD: C. Hartnack, J. Aichelin
Potential:
V=30MeV @ 
IQMD distribution normalized to the region mT>360 MeV/c
The good statistics of data at low Momentum (P<200 MeV/c) can provide new insight in the study of the in-medium potential.
Calculation with Potential seems to reproduce better the data.
PRELIMINARY
Strange Quark Matter 2008, Beijing

17. Strange Quark Matter 2008, Beijing
K+/- Identification
A. Schmah
Strange Quark Matter 2008, Beijing

18. Strange Quark Matter 2008, Beijing
Kaon Identification
TOF
M. Lorenz
Tofino
S/B:
K+:
K- :
Spectra refer to Identification only in the TOF Region.
Strange Quark Matter 2008, Beijing

19. Strange Quark Matter 2008, Beijing
MT distribution for K
Efficiency and acceptance corrected spectra
PRELIMINARY
midrapidity
Strange Quark Matter 2008, Beijing

20. Rapidity Density Distribution for K
PRELIMINARY
Strange Quark Matter 2008, Beijing

21. Strange Quark Matter 2008, Beijing
Comparisons with KaoS
PRELIMINARY
K-/K+ ratio fit nicely in the systematics of the KAOS Data
A. Foerster et al., Phys. Rev. C
Statistical Model
J. Cleymans et al. Phys. Rev. C 59 (1999)
Strange Quark Matter 2008, Beijing

22. Strange Quark Matter 2008, Beijing
The 
A. Schmah
TOF
Tofino
Mixed event background normalized in the mass region MeV/c2
PRELIMINARY
Combination of K in TOF and Tofino
Strange Quark Matter 2008, Beijing

23. First MT Spectrum for  at SIS
PRELIMINARY
Width of the Rapidity Distribution
Pure statistical errors are shown
Strange Quark Matter 2008, Beijing

24. Strange Quark Matter 2008, Beijing
Strangeness Balance
Particle
Multiplicity/LVL1 in 4
Teff [MeV] p p-
L+S0 K- K+ f
FOPI Result compatible with 0!:

M. Merschmeyer et al. Phys. Rev. C76:
Strange Quark Matter 2008, Beijing

25. Strange Quark Matter 2008, Beijing
K- Sources
K- Production via Strangeness Exchange: K+ K- c
10-15 fm/c
Dominant mechanism K-, for production of mainly motivated by the fact that K- and K+ multiplicity scales similarly with Apart and difference in TB.
A. Foerster et al., Phys. Rev. C
On the other hand we have measured:
Which translates in:
K-stemming from Decay.
This can be considered as a lower limit, since we would not see K decaying in medium even if the  width would be modified (in vacuum: )
Strange Quark Matter 2008, Beijing

26. Strangeness Suppresion ?
H. Oeschler, K Redlich
PRELIMINARY
Au+Au:
B. Holzman (E917) Nucl. Phys. A 698 (2002)
S.V. Afanasiev et al. (NA49) Phys. Lett. B 491(2000) 59.
J.Adams et al. (STAR) Phys. Lett B 612 (2005)
Strange Quark Matter 2008, Beijing

27. Strange Quark Matter 2008, Beijing
Epilogue
High Quality and Statistic Data have been collected for the reaction 1.75AGeV for K,K0, and
The good measurement of the low Momentum range for K0S can provide some informations about the K-Nucleus potential
For the first time at SIS K and have been easured at the same time with such quality
the /K- ratio shows that a good percentage of the K- stemms from the  decay and hence this process concurrs with the strangeness echange mechanism in the production of K- in heavy ion reactions.
...Better statistics and phase space coverage up tp Midrapidity will be achieved with HADES starting from thanks to the RPC upgrade.
Ni+Ni and Au+Au will be measured.
RPC
Strange Quark Matter 2008, Beijing

28. Strange Quark Matter 2008, Beijing
Anticipation...
P.Chung. Et al (E895) Phys. Rev. Lett (2003).
C. Alt et al. (NA49) arXiv: (2008)
J.Adams et al. (STAR) Phys. Rev. Lett (2007
R. Kotte
PRELIMINARY ?
reconstructed from  invariant Mass
Can the existing statistical Model describes the ) Ratio at SIS?
To be continued at SQM2009 in Brasil
Strange Quark Matter 2008, Beijing

29. Strange Quark Matter 2008, Beijing
The HADES Collaboration
Bratislava (SAS, PI)
Catania (INFN - LNS)
Cracow (Univ.)
Darmstadt (GSI)
Dresden (FZR)
Dubna (JINR)
Frankfurt (Univ.)
Giessen (Univ.)
Milano (INFN, Univ.)
Munich (TUM)
Moscow (ITEP, MEPhI, RAS)
Nicosia (Univ.)
Orsay (IPN)
Rez (CAS, NPI)
Sant. de Compostela (Univ.)
Valencia (Univ.)
Coimbra (Univ.)
GSI
The collaboration consists of 17 institutions in 10 countries and is distributed all over Europe.
Strange Quark Matter 2008, Beijing

30. Rapidity Distribution for and
PRELIMINARY
IQMD: C. Hartnack, J. Aichelin
The IQMD calculations with and without potential are normalized to the experimental yield.
The comparison shows that IQMD reproduces the rapidity distribution and that the width is independent from the potential
Strange Quark Matter 2008, Beijing

31. Strange Quark Matter 2008, Beijing
/K- Ratio
PRELIMINARY
Strange Quark Matter 2008, Beijing