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Searching for Strange Quark Matter with the CMS/CASTOR Detector at the LHC P. Katsas, A.D. Panagiotou, E. Gladysz for the CMS/CASTOR Group

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Presentation on theme: "Searching for Strange Quark Matter with the CMS/CASTOR Detector at the LHC P. Katsas, A.D. Panagiotou, E. Gladysz for the CMS/CASTOR Group"— Presentation transcript:

1 Searching for Strange Quark Matter with the CMS/CASTOR Detector at the LHC P. Katsas, A.D. Panagiotou, E. Gladysz for the CMS/CASTOR Group / CMS-HI meeting,

2 ● Motivation: Unconventional Events in Cosmic Rays ● Phenomenological Models & MC Simulations ● “Strangelet” Identification Analysis ● Summary Outline

3 Homogeneous thick lead chamber Centauro Hadron – Rich CR Events Normal

4 Measurement settings: 100 μm shower core diameter  threshold ~ 3 TeV (Strangelet ?) 3.6 λ I 3.2 λ I 3.6 λ I 1.5 λ I Hadron limit Hadron limit

5 Estimates for Centauro at LHC Energy density ε ~ GeV/fm 3, Temperature T ~ MeV Baryochemical potential µ b ~ GeV/fm 3 CNGEN Centauro & Strangelet Generator Phys. Rev. D45(1992)3134 Astroparticle Phys. 2(1994)167 Astroparticle Phys. 13(2000)173 Phys. Atom. Nucl. 67(2004)396 anti- 

6 N = 2352 N = 108 Multiplicity in CASTOR Acceptance CENTAURO HIJING Low multiplicity High multiplicity mostly baryons + kaons dominated by pions Simulations - CNGEN 5.2 <  < 6.5 T = 250 MeV,  q = 600MeV,  y stop = 3.0 idpart

7 CASTOR Probability of Centauro & Strangelet Detection ~ 60 % of Centauro decay products and ~ 10% of Strangelets within CASTOR acceptance  = 9 GeV/fm 3, T = 250 MeV,  q = 330 MeV,  y stop = 3.0   Estr (GeV) 5.2<  < 6.5

8 MC Radial Acceptance of CASTOR

9 Strangelets from Centauro Decay ∆y stop ~ 2 – <  Expected at LHC: ● Energy densities up to є ~ 25 GeV/fm 3 ● ∆y stop ~ HIJING,VENUS ● ∆y stop ~ 2.3 BRAHMS-RHIC  several to ~ 25% strangelets with energies E > 7 TeV, sufficiently high to be detected. T = 350 MeV T = 300 MeV T = 250 MeV

10 Stable Strangelet interaction in CASTOR MC-algorithm Strangelet is considered with radius: Mean interaction path: Strangelets passing through the detector collide with W nuclei: Spectator part is continuing its passage. Wounded part produces particles in a standard way. Particles produced in successive interactions initiate electromagnetic- nuclear cascades. Process ends when strangelet is destroyed. E. Farhi, R. Jaffe, Phys.Rev.D30(1984)2379; M. Berger, R. Jaffe, Phys.Rev.C 35(1987)213, G.Wilk y, Z.Wlodarczyk, J.Phys.G22(1996)L105; E. Gładysz, Z. Włodarczyk, J.Phys.G23(1997)2057 The rescaled r 0 is determined by the number density of the strange matter: n = A/V = (1/3)(n u +n d +n s ) where n i =- ∂ Ω i / ∂ μ i ; Ω(m i,μ i,α s ), taking into account the QCD O(α s ) corrections to the properties of SQM. sss

11 Unstable Strangelet in Pb chamber MC Simulation 7 Neutrons

12 Similarity between the experimental data (squares) and simulated cascades produced by a bundle of seven neutrons (full histogram). (a)Distribution of mutual distance between the consecutive maxima; (b)Distribution of ratios of the energy contained in the particular maxima to the average energy of the humps. Comparison Data with Simulation

13 MC - Stable Strangelet in CASTOR CASTOR Geometry configuration 1 layer: 5mm W+2mm quartz plate ~2.4 X 0 1 RU = 7 layers per readout unit 16 (in  x 18 (in z) readout channels Total depth: ~ 10.5 Λ int Low Energy Strangelets (~5 TeV) may be seen above background. HIJING Depth

14 A=15, E=7.5 TeV A=10, E=5 TeV 60 pions, 1TeV each Stable Strangelet in CASTOR

15 Full CASTOR Calorimeter Stage I Stage II Segmentation: 14(depth) x 16(azimuth) = 224 channels

16 230906CMS-HI/ Apostolos D. Panagiotou16 HIJING Pb+Pb Event at √s = 5.5 TeV E tot ~ 130 TeV ~ 8 TeV/sector N < 100/sector GeV η η

17 230906CMS-HI/ Apostolos D. Panagiotou17 Fluctuations in Cascade Profile in Sectors Calorimeter Depth (RUs) Energy HIJING

18 230906CMS-HI/ Apostolos D. Panagiotou18 Fluctuations in Energy Distribution in Sectors En. Distribution in sector / Average En. Distribution 1 16 HIJING 2 15

19 Strangelet signatures Azimuthal asymmetry in energy deposition FluctuationsLongitudinal transition curves  Event-by-event analysis  Analysis procedure in 2 steps: average distribution energy distribution per RU Large magnitude of energy fluctuations in RUs manifest abnormal transition curves Strangelet identification & Analysis (i = 1 – 16 sectors) = mean energy in sectors σ sd = standard deviation of the distribution of the energies E i

20 Analysis of HIJING Event Need to analyze 10 4 events

21 HIJING Strangelet in one sector Energy in RUs Energy distributions in CASTOR (Depth) A = 15 E = 7.5 TeV Average of 16 Sectors Energy RU Sector Total Energy in Sectors

22 Pb+Pb HIJING + Strangelet

23 Pb+Pb HIJING + Strangelet Cascade Profile in Sector Depth

24 230906CMS-HI/ Apostolos D. Panagiotou24 Analysis with Strangelet E str = 7.5 TeV E str = 10 TeV EM-cut only H-section EM+H section sector containing Strangelet + HIJING sectors containing HIJING Pb+Pb σEσE σ fluctuations

25 E str = 7.5 TeV Strangelet in between two Sectors Energy Distribution in Sectors Sectors with Strangelet ~ 14% with E i /E j = 50/50 – 75/25

26 E str = 7.5 TeV Strangelet in between two Sectors Transition Curves Depth HIJING + Strangelet

27 Analysis with Strangelet in two Sectors EM-cut Sectors with Strangelet

28 Strangelets of various Energies 15 TeV 10 TeV 7.5 TeV EM-cut

29 230906CMS-HI/ Apostolos D. Panagiotou29 Comparison of Observed and Input MC Strangelet Efficiency of Identification E obs ~ 97% Observed Strangelet ≡ Average Energy distribution of mixed event – Energy distribution in sector containing Strangelet

30 The probability for a hadron-rich ‘Centauro-type’ event, estimated from statistics of Chacaltaya and Pamir experiments for cosmic ray families with visible energy greater than 100 TeV, is about 3%. In about 10% of these hadron-rich events, strongly penetrating cascades, clusters, or ”halo” were observed. We assume the total probability for “Long Flying Component” (Strangelet?) production in central nucleus- nucleus collisions to be approximately: 0.03 x 0.1 ~ O(10 −3 ). At LHC kinematics, the percent of Strangelets falling in CASTOR phase space is ~ 10% of total number of Strangelets produced in central Pb-Pb collisions. This quantity depends on the mass and energy of the Strangelet, as calculated by the “Centauro model” MC code CENGEN. A rough estimation of the total probability for Strangelet production and detection in CASTOR is: P CASTOR strangelet ≈ 10 −3 × 0.1 ≈ O(10 −4 ) This number, even if it is uncertain by an order of magnitude down, is a very large number ! Cross Section Estimation for Strangelets

31 Characteristics of a “Strangelet event”: 1.Sector(s) with much higher energy than the average. 2.Strong fluctuations in the longitudinal cascade profile of the sector. 3.Large E had /E em for the event (Hadron-rich event). Summary

32 A str = 15 E str = 5 TeV


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