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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Feasibility of hyperons study with ECAL
Sergey Kiselev, ITEP Moscow, for the ECAL group
Introduction Motivation Input info and assumptions Spectra Acceptance Multiplicity Signal Signal + Background Conclusions and next steps
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Introduction Hyperons with “neutral” decay modes:
Σ-(dds) n - Br=99.8% c=4.4 cm Σ+(uus) p o Br=51.6% c=2.4 cm Σ+(uus) n + Br=48.3% Σo (uds) Λ Br=100% c=2.2 10-9 cm o(uss) Λ o Br=99.5% c=8.71 cm
p, -, +, Λ p - can be identified by TOF. , n, o can be identified by ECAL. Measurements with the CBM (Compressed
Baryonic Matter) detector will be analyzed.
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Introduction - the CBM detector
Tracking: STS, TRD
Vertexing: STS
Hadron ID : TOF
Electron ID: RICH, TRD, ECAL
, neutral m, n: ECAL
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Motivation - 1 The pronounced kink
structure in the K+/+ ratio has caused speculations on a possible deconfinement phase transition around 30 AGeV
Which part of Λ is from the channel Σo Λ ?
How do Σ+ Σo Σ- excitation functions look like?
Excitation function of strangeness production in central Au+Au and Pb+Pb collisions.
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Motivation - 2 Hyperon-hyperon
interactions: to verify various ideas
on baryon-baryon interactions such as the flavor SU(3) symmetry
to clarify the properties of dense nuclear matter like neutron stars, in which abundant hyperons are expected to exist
Experimental method – momentum correlations between strange baryons.
baryon octet matrix
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Input info and assumptions CbmRoot package (04.10.2004), Geant3 105 UrQMD Au+Au central events at 25 AGeV TOF:
p, - : ideal tracking and PID, momentum resolution 1%, impact parameter cut b>0.1 cm, cross last 4 STS tracking stations (Zvtx < 40 cm)
ideal Λ p - reconstruction; ECAL:
: ideal PID, energy resolution 3%/√E, 6%/√E, 9%/√E n: ideal PID, momentum from ECAL time v=L/t, dp/p =
(1+(p/m)2) dL/L, time resolution 0.2, 0.4, 0.6, 0.8 ns dp/p = (1+(p/m)2) dt/t
ideal o reconstruction
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σ- n -: spectra
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σ- n -: acceptance
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σ- n -: multiplicity
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Σ- n -: signal
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Σ- n -: signal + background
σt = 0.2 ns σt = 0.4 ns σt = 0.6 ns σt = 0.8 ns
S/B(%) 0.17 0.14 0.12 0.11
Signif. 22 20 18 18
Σ- n -: signal+background
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Σ+ p o: spectra
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σ+ p o: acceptance
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Σ+ p o: multiplicity
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Σ+ p o: signal
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Σ+ p o: signal + background
3%/√E 6%/√E 9%/√E
S/B(%) 0.37 0.19 0.13
Signif. 16 12 10
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Σo Λ : spectra
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σo Λ : acceptance
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Σo Λ : multiplicity and cuts
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σo Λ : signal
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13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev
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Σo Λ : signal + background
3%/√E 6%/√E 9%/√E
S/B(%) 0.29 0.16 0.12
Signif. 10.5 7.7 7.0
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Conclusions and next steps Conclusions:
S/B=0.1 – 0.3 %, needed statistics >107
Σ-, Σ+, Σo can be reconstructed with ECAL by the event-mixing technique
S/B(Σ+ p o) > S/B(Σ+ n +) Next steps:
o Λ o
More realistic simulations: tracking, PID, reconstruction