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Searching for Strange Quark Matter with the CMS/CASTOR Detector at the LHC Apostolos D. Panagiotou, University of Athens for the CMS/CASTOR Group http://cmsdoc.cern.ch/castor /.

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Searching for Strange Quark Matter

with the CMS/CASTOR Detector at the LHC

Apostolos D. Panagiotou, University of Athens

for the CMS/CASTOR Group

http://cmsdoc.cern.ch/castor/

V International Conference on PERSPECTIVES IN HADRONIC PHYSICS Particle-Nucleus and Nucleus-Nucleus Scattering at Relativistic Energies

ICTP 22-26 May, 2006


Outline

  • CASTOR Calorimeter at CMS

  • Exotic Events in Cosmic Rays

  • Phenomenological Models & MC Simulations

  • “Strangelet” Identification Analysis

  • CASTOR Prototypes - Beam test Results

  • Summary



CMS Forward Detectors

CASTOR

5.2 < η < 6.6


CASTOR Calorimeter

Segmentation: 16(azimuth) x 14( in depth) = 224 channels

Stage II

Stage I


CASTOR Calorimeter

Stage II

16x4 = 64 Channels

Stage I

PMT

W/Q plates

16x10 = 160 Channels

Air-core Light Guide subtending 5 W/Q plates

H section 10.3λΙ

EM section 20 Xo



61 mm Pb

Typical Emulsion / Lead Chambers


STRONGLY PENETRATING COMPONENT

cascades, clusters, halos,

frequently accompanying CR

hadron-rich events.

ADP, Zeits. Phys. A- Atomic Nuclei 333(1989)355

E.G.-D. Phys. Part. Nucl34(2003)285

Exotic Cosmic Ray Events

CENTAURO SPECIES

Abnormal hadron dominance (in N and E), high pT, low multiplicity

  • CENTAURO of original type (5 “classical” Chacaltaya + over a dozen others) Nh ~ 100, pT ~ 1.75 GeV/c

  • MINI-CENTAUROS

  • CHIRONS


Hadron – Rich CR Events

Homogeneous thick lead chamber

Centauro

Normal


(Strangelet ?)

1.5 λI Hadron limit

3.6 λI

Measurement settings:

100 μm shower core diameter  threshold ~ 3 TeV

3.6 λI

3.2 λI

Hadron limit



Estimates for Centauro at LHC

  • Energy density

    ε ~ 3 - 25 GeV/fm 3,

  • Temperature

    T ~ 130 - 300 MeV

  • Baryo-chemical potential

    µb ~ 0.9 - 1.8 GeV/fm3

    CNGEN

    Centauro & Strangelet Generator

anti-

Phys. Rev. D45(1992)3134Astroparticle Phys. 2(1994)167 Astroparticle Phys. 13(2000)173 Phys. Atom. Nucl. 67(2004)396


Conditions for DQM-bag Stability Pqg = B

Minimization of Bag energy (dE/dR = 0) in spherical DQM distribution with radius R and Nq massless quarks.

Pressure of (u,d) quark-gluon plasma

Pqg = (8/45)π2Τ4 +μq2Τ2 + μq4/2π2= (2.034Νq/4π)(1/R4) = B

For CR Centauro (μq~ 600 MeV, T ~ 130 MeV, Nq ~ 225) R = roNb1/3 ~ 1.43 fm  ro = 0.34 fm (~ ro ‘collapsed’ nucleus)

Astroparticle Phys.13(2000)173


SQM: “Strangelet” Neutron Star

QCD true Ground State


StableStrangelet interaction in CASTORMC-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


CASTOR Geometry configuration

1 layer: 5mm W+2mm quartz plate ~2.37 X0

1 RU = 7 layers per readout unit

16 (in  x 18 (in z) readout channels

Total depth: ~300 X0, 10.5 Λint

LOW ENERGY STRANGELETS (~5 TeV)

MAY BE SEEN ABOVE BACKGROUND

300 X0

MC - Stable Strangelet in CASTOR

P. Katsas

HIJING

Depth

HIJING



CASTOR Calorimeter

Segmentation

14 Sections/Sector (longitudinal)

16 Sectors (azimuthal)


HIJING Pb+Pb Event at √s = 5.5 TeV

η

GeV

Etot ~ 130 TeV ~ 8 TeV/sector

N < 100/sector

η

GeV

ICTP/ Apostolos D. Panagiotou


Total Energy Distribution in Sectors - HIJING

Energy

ICTP/ Apostolos D. Panagiotou

Calorimeter Depth (RUs)


Total Energy in Sector

Energy in RU

Total Energy in Sector

Energy in RU

HIJING

Strangelet in one sector

Energy distributions in CASTOR

Average of 16 Sectors

A = 15 E = 7.5 TeV

<E>

Energy

(Depth)

RU

Sector

(Depth)

RU

Sector


Strangelet signatures

Azimuthal asymmetry

in energy deposition

Longitudinal

transition curves

energy distribution per RU

average distribution

Large magnitude of energy

fluctuations in RUs manifest

abnormal transition curves

Strangelet identification & Analysis

  • Event-by-event analysis

  • Analysis procedure in 2 steps:

<E> = mean energy in sectors

(i = 1 – 16 sectors)


Analysis results w t background
Analysis Results w/t background

Estr = 10 TeV

Estr = 7.5 TeV

σE

sector containing

Strangelet + HIJING

sectors containing

HIJING Pb+Pb

σfluctuations

EM-cut

only H-section

EM+H section

ICTP/ Apostolos D. Panagiotou


Prototypes - Beam test Results

L. Gouskos

CMS Reports NIM publications



CASTOR Proto II Beam Test

4(6)-APDs

4-APDs

4-APDs

4-APDs

4-APDs

APDsPMT







Summary

  • CASTOR is the experimental tool for ‘Centauro’ and ‘Strangelet’ search in the forward rapidity at CMS

  • Identification through measurements of:

    • Extreme imbalance between hadronic and electromagnetic energy.

    • Non-uniform azimuthal energy deposition.

    • Penetrating objects beyond the range of normal hadrons  abnormal longitudinal energy deposition pattern.

Observation of Centauro and (meta) stable SQM will have significant implications for QM-Physics and Astrophysics.


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