IDENTIFYING A STRANGELET IN 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
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Outline

• CASTOR Calorimeter at CMS
• Exotic Events in Cosmic Rays
• Phenomenological Models MC Simulations
• Strangelet Identification Analysis
• CASTOR Prototypes - Beam test Results
• Summary

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CASTOR Calorimeter at CMS
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CMS Forward Detectors
CASTOR
5.2 lt ? lt 6.6
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CASTOR Calorimeter
Segmentation 16(azimuth) x 14( in depth) 224
channels
Stage II
Stage I
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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 10.3 ??
EM section 20 Xo
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Exotic Events in Cosmic Rays
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61 mm Pb
Typical Emulsion / Lead Chambers
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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

• 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

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Hadron Rich CR Events
Homogeneous thick lead chamber
Centauro

Normal
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(Strangelet ?)
1.5 ?I Hadron limit
3.6 ?I
Measurement settings 100 µm shower core diameter
? threshold 3 TeV
3.6 ?I
3.2 ?I
Hadron limit
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Phenomenological Models MC Simulations
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anti-
?
Phys. Rev. D45(1992)3134 Astroparticle Phys.
2(1994)167 Astroparticle Phys. 13(2000)173 Phys.
Atom. Nucl. 67(2004)396
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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)p2?4 µq2?2 µq4/2p2
(2.034?q/4p)(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
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SQM Strangelet Neutron Star
QCD true Ground State
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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. Gladysz, Z. Wlodarczyk, J.Phys.G23(1997)2057

The rescaled r0 is determined by the number
density of the strange matter n A/V
(1/3)(nundns) where ni- ?Oi/?µi O(mi,µi,as),
taking into account the QCD O(as) corrections to
the properties of SQM.
s
s
s
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MC - Stable Strangelet in CASTOR
P. Katsas
HIJING
Depth
HIJING
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Strangelet Identification Analysis
P. Katsas
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CASTOR Calorimeter
Segmentation
14 Sections/Sector (longitudinal)
16 Sectors (azimuthal)
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HIJING PbPb Event at vs 5.5 TeV
?
GeV
Etot 130 TeV 8 TeV/sector
N lt 100/sector
?
GeV
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Total Energy Distribution in Sectors - HIJING
Energy
Calorimeter Depth (RUs)
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Energy distributions in CASTOR
A 15 E 7.5 TeV
Average of 16 Sectors
ltEgt
Energy
(Depth)
RU
(Depth)
RU
Sector
Sector
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Strangelet identification Analysis

• Event-by-event analysis
• Analysis procedure in 2 steps

ltEgt mean energy in sectors
(i 1 16 sectors)
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Analysis Results w/t background
Estr 10 TeV
Estr 7.5 TeV
sE
3s
sector containing Strangelet HIJING
sectors containing HIJING PbPb
sfluctuations
EM-cut only H-section
EMH section
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Prototypes - Beam test Results
L. Gouskos
CMS Reports NIM publications
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CASTOR Proto I Beam Test
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CASTOR Proto II Beam Test
4(6)-APDs
4-APDs
4-APDs
4-APDs
4-APDs
APDs PMT
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Energy Resolution - Electrons
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Energy Resolution - Hadrons
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SEMI-OCTANT GEOMETRY PROJECTION
Ee 200 GeV
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Spatial X-scan Electrons Width of Shower
s?? 1.9 mm
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Spatial X-scan Pions Width of Shower
sH 5.3 mm
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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.