Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 1 Challenges in Physics &...
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Transcript of Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 1 Challenges in Physics &...
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 1
Challenges in Physics & Instrumentation
Results from Heavy Ion and Elementary Reactions
Summary & Outlook
Dilepton MeasurementsDilepton Measurementswith HADESwith HADES
Christian Müntz Christian Müntz (Univ. Frankfurt),(Univ. Frankfurt),for the HADES Collaborationfor the HADES Collaboration
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 2
The CollaborationThe Collaboration
GSIGSI
SISSIS
Catania (INFN - LNS), Italy
Cracow (Univ.), Poland
Darmstadt (GSI), Germany
Dresden (FZD), Germany
Dubna (JINR), Russia
Frankfurt (Univ.), Germany
Giessen (Univ.), Germany
Milano (INFN, Univ.), Italy
Munich (TUM), Germany
Moscow (ITEP,MEPhI,RAS),
Russia
Nicosia (Univ.), Cyprus
Orsay (IPN), France
Rez (CAS, NPI), Czech Rep.
Sant. de Compostela (Univ.), Spain
Valencia (Univ.), Spain
Coimbra (Univ.), LIP, Portugal
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 3
© A.Drees
OrientationOrientation
Sources for dileptonSources for dilepton
production in (ultra-)production in (ultra-)
relativistic HICsrelativistic HICs
Add…Add…
Accuracy
Significance
Systematics
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 4
10 20 30t [fm/c]
≈ 10 fm/c
PhysicsPhysics Motivation Motivation
Vector mesons (VM)Vector mesons (VM): Optimum choice!Optimum choice!
VM life time comparable to system life time
Interplay with baryonic resonances
Decay in dileptons: Direct probe, final state
interaction minimized!
The SIS heavy ion energy regime:The SIS heavy ion energy regime:
Probing nuclear matter at “moderate”…
- Densities (/o = 1…3), and
- Temperatures (T < 100 MeV)
A long life time of the dense system (up tp 10 fm/c)
The all-dominant presence of baryonic resonances (“resonance matter”, 33), N/Apart ≈ 10%
The sub-threshold production of Kaons and Vector Mesons: Multi-step processes confined to the dense phase
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 5
The MissionThe Mission
HHigh igh AAcceptance cceptance DDiiEElectron lectron SSpectrometerpectrometer
Focus on the spectroscopy of vector mesons ()
Consistent picture in pp, pA, A and AA reactions
Supplemented by hadron spectroscopy, incl. K0
s, ,
Instrumental challenge!Instrumental challenge!
VM: rare probe:
1 VM per 1-10 Million reactions!
Large background from conversion and 0-Dalitz decay
Spectrometer with a …Spectrometer with a …
High geometric acceptance & invariant mass resolution
High background rejection & rate capability, dedicated LVL2 trigger
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 6
The SetupThe Setup
START
Acceptance: Full azimuth, polar angles 18o - 85o
Pair acceptance 0.35 About 80k detector channels
Forward
Hodoscope
<7o
Side View
Opening angle > 9o
Pair acceptance
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 7
Completed RunsCompleted Runs
Physics Runs in…
p, d, - induced A + A Status/Comment
2002 C + C 2 AGeV Published!
2004 C + C 1 AGeV Analysis finished
2004 p + p 2.2 GeV Analysis finished
2005 Ar + KCl 1,75 AGeV Analysis ongoing
2006 p + p 1.25 GeV Analysis ongoing
2007 p + p 3.5 GeV
d + p 1.25 AGeV
… online results!
2008 p + A 3.5 GeV
2008/9 Upgrade RPC, DAQ
2009 Ni + Ni Planned
2010 + N, A
2011 Au + Au
> 2011 Hades goes FAIR (8 AGeV)
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 8
Hadrons: Advances in Particle IDHadrons: Advances in Particle ID
Standard PID via time-of-flight & momentum
NewNew: dE/dx from tracking (MDC)
Dedicated cuts to increase (e.g. kaon) signal.MDC I MDC II MDC III MDC IV
Truncated mean is calculated from all measurements of a track
particle track
K+
p+-
K-
Ar + KCl, 1.75 AGeV
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 9
Ar + KCl, 1.75 AGeVAr + KCl, 1.75 AGeV
Invariant mass distributionsInvariant mass distributions30% of total statisticsPreliminary!Mixed event technique background (Ks
o,) 0
SK
p KK
Ph
D t
hesis
A
.Sch
mah
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 10
Hadrons: Charged Pions Hadrons: Charged Pions
C + C, 2 AGeVC + C, 2 AGeV
Anisotropy:
Used for the Normalization of dilepton spectra, properly extrapolated to 4
π+y =
0.1-0.20.2-0.30.3-0.40.4-0.50.5-0.60.7-0.80.8-0.90.9-1.01.0-1.11.1-1.21.2-1.31.4-1.51.5-1.61.6-1.71.7-1.8
*) 11% syst, error, in agreement with KaoS, TAPS **) preliminary
1 AGeV **) 2 AGeV *)
N< -+>/Apart 0.069 ± 0.008 0.137 ± 0.015
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 11
Details moved to the backup slides…!Details moved to the backup slides…!
Lepton candidate selectionLepton candidate selection
Spatial correlations
PID
Background rejectionBackground rejection
ConversionConversion
00-Dalitz-Dalitz
Combinatorial backgroundCombinatorial background
Same event like sign pairsSame event like sign pairs
Mixed event opposite sign pairsMixed event opposite sign pairs
Lepton Analysis: TechnicalitiesLepton Analysis: Technicalities
e+
e- ~ 0.70
Conversion
e+
e-
0
~ 2.20
Dalitz
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 12
C + C, 2 AGeV, vs. Hadronic CocktailC + C, 2 AGeV, vs. Hadronic Cocktail
► Cocktail A:Cocktail A: 0 + η + ω (long lived)
► Cocktail B: A & Cocktail B: A & Δ(Ne+e-), ρ
(short lived)18 %18 % 21 %21 %
systematic errors:systematic errors:15 % - efficiency correction 10 % - combinatorial background11 % - 0 normalization
Ph
D th
esis
: M.
Su
dol
PRL 98, 052302 (2007)PRL 98, 052302 (2007)- Normalized to ½(+ + -) yield - M <150 MeV/c2: ~23000 counts
- M-≥150 MeV/c2: ~ 3000 counts
(M(Meeee) ~9 % @ M) ~9 % @ Meeee~0.8 GeV/c~0.8 GeV/c22
Event generator PLUTOEvent generator PLUTO :
thermal source (T=80MeV)
polar angle distribution from charged analysis
η (TAPS data)
ρ, ω: m -scaling
Δ scales with
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 13
pp┴┴, y distributions compared to cocktail, y distributions compared to cocktail
► C + C, 2 AGeVC + C, 2 AGeV
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 14
C + C, 1 AGeV, preliminary dataC + C, 1 AGeV, preliminary data
Preliminary!Preliminary!- Normalized to ½(+ + -) yield - M <150 MeV/c2: ~17780 counts- M-≥150 MeV/c2: ~ 646 counts
Event generator PLUTOEvent generator PLUTO : Thermal source (T=55MeV) polar angle distribution from charged analysisη (TAPS data) ρ, ω: m -scalingΔ scales with
22-25 %22-25 %
systematic errors:systematic errors:20 % - efficiency correction 10 % - combinatorial background11 % - 0 normalization
Ph
D th
esis
: Y. P
ach
mayer, T
. Ch
rist
► Cocktail B: A & Cocktail B: A & Δ(Ne+e-), ρ (short lived)
PRELIMINA
RY
► Cocktail A:Cocktail A: 0 + η + ω (long lived)
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 15
Comparison 1 – 2 AGeVComparison 1 – 2 AGeV
PRELIMINA
RY
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 16
PRELIM
INARY
Comparison 1 – 2 AGeVComparison 1 – 2 AGeV
Inv. Mass spectrum normalized to hadronic cocktail of long lived mesonic components
Agreement @ Mee < 0.15 GeV/c2.
Large relative excess compared to cocktail A, similar in shape.
Quantitative analysis: deduce the absolute excess yield Yexc (beyond η), making use of the TAPS η data:
Excess Excess (beyond η) scales like pions.scales like pions.
DLS…DLS…
C + C 2 AGeV Phys. Rev. Lett. 98, 052302 (2007)
η
η
(2.0)13 3 (stat)
(1.04)
Y
Y TAPS:TAPS:
Yexc(2.0)/Yexc(1.0) = 2.3
± 0.6(stat) ± 1.0(sys)
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 17
1 AGeV: Comparison to DLS1 AGeV: Comparison to DLS
Different phase spaceDifferent phase space coverage of HADES and DLS
ExtrapolationExtrapolation of HADES data:
Inspired by the thermal model
HADES & DLS Filters applied
Processed separately for low (M<150GeV/c2) and high inv. masses
DLS Data:
R.J. Porter et al.: PRL 79(97)1229
PRELIMINARY
DLS data (C+C, 1AGeV) confirmed by HADES!
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 18
pp┴┴ Distributions compared to the Cocktail Distributions compared to the Cocktail
PRELIMINARY
PRELIMINARY
PRELIMINARY
J. Carroll – presentationInternational Workshop on Soft Dilepton ProductionAugust 20-22,1997, LBNL
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 19
Heavy Ion Heavy Ion → Elementary Reactions→ Elementary Reactions
C + C summary:C + C summary:
DLS data confirmed
Significant excess @ Mee > 150 MeV/c2
- Energy excitation function like pions.
- Evidence for missing yield @ low-pt
Contributions of pN Bremsstrahlung and N*(Contributions of pN Bremsstrahlung and N*() decay?) decay?
No precise data available! (N*() Ne+e- BR, EM transition FF)
Measure Measure elementary reactionselementary reactions, e.g.:, e.g.:
DiElectron sources in pn, pp below the DiElectron sources in pn, pp below the ηη threshold threshold
Measure pp+pppe+e- (fix +, brems (pp) is small)
Measure pn e+e-X with dp reactions → brems (pn)
- Experimental technique: tag projectile spectator protons!
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 20
p+n tagging in d+p reactionsp+n tagging in d+p reactions
Installation of the (rearranged) Forward Hodoscope FH, formerly used at Bevalac and KaoS/SIS (for event plane analysis).
p_spec
pTd
pT
FH, Θ < 7o,added 2007
(n)LH2 target
(Orsay)
pp contamination 10% only.
Preliminary online results from May 2007May 2007
ToF-Tagging of the projectile spectator proton with the Forward Hodoscope FH (Θ < 7o).
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 21
p+p, p+np+p, p+nee++ee-- X, 1.25 GeV X, 1.25 GeV
Not corrected for efficiency; in the HADES acceptance, 50% of available statistics
Red line: Pluto hadronic cocktail (properly treated for acceptance/efficiency)
Only 2 sources: 0 e+e- , + pe+e- (BR=4.4*10-5 )
(+ yield fixed to 0 with isospin relation: N(+)=3/2 N(0))
PRELIMINARY
PRELIMINARY
n + p, 1.25 GeV
e+e- > 90
PhD thesis T.Galatyuk Online spectrum► Factor 2 (pp), 4-5 (np) missing for M > 150 MeV/c2
► Evidence for additional sources!
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 22
Online: p+p, 3.5 GeVOnline: p+p, 3.5 GeV
May 2007May 2007, preliminary, online results!
No final calibration/alignment!
ee++ee-- pair analysis pair analysis:
not shifted! Preliminary calibration…
Extra yield below VM pole mass.
S/BS/B1010
11
0.5 1.0 0.5 1.0
MMeeee
Preliminary
Preliminary
PRELIMINARY
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 23
Summary & OutlookSummary & Outlook
Physics Runs in…
p, d, - induced A + A Status/Comment
2002 C + C 2 AGeV Published!
2004 C + C 1 AGeV Analysis finished
2004 p + p 2.2 GeV Analysis finished
2005 Ar + KCl 1,75 AGeV Analysis ongoing
2006 p + p 1.25 GeV Analysis ongoing
2007 p + p 3.5 GeV
d + p 1.25 AGeV
… online results!
2008 p + A 3.5 GeV
2008/9 Upgrade RPC, DAQ
2009 Ni + Ni Planned
2010 + N, A
2011 Au + Au
> 2011 Hades goes FAIR (8 AGeV)
►HADES took off and is contributing with high-quality
data to the understanding of the di-electron production
in heavy ion collisions in the SIS energy regime,
characterized by VM production close to the threshold
and the crucial role of baryonic resonances.
►The physics program will be continued by aiming at
heavier systems and pion-induced reactions.
Christian Müntz (Univ. Frankfurt) for the HADES Collaboration, CPOD 2007 24
Towards FAIRTowards FAIR
HADESHADES2 – 8 AGeV2 – 8 AGeV
CBMCBM8 – 45 AGeV8 – 45 AGeV