feasibility of hyperons study with ecal

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

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.

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

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.

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

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

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ- n -: spectra

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ- n -: acceptance

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ- n -: multiplicity

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ- n -: signal

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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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

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ+ p o: spectra

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

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ+ p o: multiplicity

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σ+ p o: signal

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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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

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σo Λ : spectra

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σo Λ : acceptance

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σo Λ : multiplicity and cuts

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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Σo Λ : signal

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

13.03.2006 Workshop of European Research Group on Ultrarelativistic Heavy Ion Physics. Dubna-ITEP S.Kiselev

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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