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Searching for Strange Quark Matter

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Presentation on theme: "Searching for Strange Quark Matter"— 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 Outline Motivation: Unconventional Events in Cosmic Rays
Phenomenological Models & MC Simulations “Strangelet” Identification Analysis Summary

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

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

5 Estimates for Centauro at LHC Centauro & Strangelet Generator
Energy density ε ~ GeV/fm 3, Temperature T ~ MeV Baryochemical potential µb ~ GeV/fm3 CNGEN Centauro & Strangelet Generator anti- Phys. Rev. D45(1992)3134 Astroparticle Phys. 2(1994)167 Astroparticle Phys. 13(2000)173 Phys. Atom. Nucl. 67(2004)396

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

7 Probability of Centauro & Strangelet Detection
5.2<  < 6.5 CASTOR Estr (GeV)  = 9 GeV/fm3, T = 250 MeV, q= 330 MeV, ystop = 3.0 ~ 60 % of Centauro decay products and ~ 10% of Strangelets within CASTOR acceptance

8 MC Radial Acceptance of CASTOR

9 Strangelets from Centauro Decay
5.2 <  < 6.5 Expected at LHC: Energy densities up to є ~ 25 GeV/fm3 ∆ystop ~ HIJING,VENUS ∆ystop ~ 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 ∆ystop ~ 2 – 3.5

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.Wilky, Z.Wlodarczyk, J.Phys.G22(1996)L105; E. Gładysz, Z. Włodarczyk, J.Phys.G23(1997)2057 The rescaled r0 is determined by the number density of the strange matter: n = A/V = (1/3)(nu+nd+ns) where ni=- ∂Ωi/∂μi; Ω(mi,μi,αs), taking into account the QCD O(αs) corrections to the properties of SQM. s s s

11 Unstable Strangelet in Pb chamber MC Simulation
7 Neutrons

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

13 MC - Stable Strangelet in CASTOR
HIJING CASTOR Geometry configuration 1 layer: 5mm W+2mm quartz plate ~2.4 X0 1 RU = 7 layers per readout unit 16 (in  x 18 (in z) readout channels Total depth: ~ 10.5 Λint Low Energy Strangelets (~5 TeV) may be seen above background. Depth HIJING Depth

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

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

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

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

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

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

20 Analysis of HIJING Event
Need to analyze 104 events

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

22 Pb+Pb HIJING + Strangelet

23 Pb+Pb HIJING + Strangelet Cascade Profile in Sector

24 Analysis with Strangelet
Estr = 10 TeV Estr = 7.5 TeV σE sector containing Strangelet + HIJING sectors containing HIJING Pb+Pb EM-cut only H-section σfluctuations EM+H section 230906 CMS-HI/ Apostolos D. Panagiotou

25 Strangelet in between two Sectors Energy Distribution in Sectors
Estr = 7.5 TeV Sectors with Strangelet ~ 14% with Ei/Ej = 50/50 – 75/25

26 Strangelet in between two Sectors Transition Curves
Estr = 7.5 TeV HIJING + Strangelet <HIJING> <HIJING> Depth Depth

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

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

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

30 Cross Section Estimation for Strangelets
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: PCASTOR 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 !

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

32 Astr = Estr = 5 TeV

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