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CASTORCentauro And Strange Object Research
Strangelet hunt at CMS
Panos KatsasUniversity of Athens, Nuclear & Particle Physics Department
for the CASTOR collaboration
Adana, Athens, Krakow, Demokritos, INR, Ioannina, MSU, Northeastern
COSMIC QCD II, Skopelos, 25/09-1/10 2005
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Outline
● CASTOR detector description● Motivation & Physics● Experimental data & model description of
strangelets● Monte Carlo results (CNGEN, HIJING)● Simulations results & CASTOR● Strangelet analysis● Summary
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CA STOR Review 26/ 05/ 05 A postolos D . Panagiotou
1
Reading Unit
Air-core Light Guide
PMTs
Beam
Active volumeW/ Q-plates Sampling Units
W-plate (octant)
Q-plate (semi-octant)
CASTOR CALORIMETER CONCEPTUAL DESIGN- Cerenkov light is generated inside the quartz plates as they are traversed by the fast charged particles in the shower (shower core detector) developing in tungsten absorber - Azimuthal and longitudinal sampling sufficient for a study of structures in longitudinal development of cascades
- High depth for detection of strongly penetrating objects
EM = 2RU (~ 28 X0) HAD = 16 RU (~10 Λ I )
RU ~ 7 Sampling U ~ .544 Λ
I ~ 14 X0
(16 azimuthal sectors)
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Detectors near beamline: Forward Physics in p+p, p+A, A+A
TOTEM T2IP
TOTEM T1HF
ZDC @ 140 m
CASTOR
•Hermetic coverage up to || ~ 6.6•Zero degree neutral energy•Physics: Centrality, Low-x, Limiting fragmentation, Strangelets, DCC
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Option 2 (preferred)
CASTOR
5.31 < < 6.84
Inner radius ~ 38 mm
Outer radius ~ 135 mm active
Outer radius ~ 280 mm total
T2 Tracker
5.32 < < 6.71
CMS Very-Forward Region
HF
3 < < 5.3
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EM - PROTOTYPE W-PLATES + Q-
FIBRE / PLATES
~ 20 Xo
H CASTOR A L
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CASTOR PROTO BEAM TEST 2003
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5mm W + 2mm Q H
3mm W + 1.5mm Q EM
Octant
Semi-Octant
CASTOR PROTO II
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4-APDs
4-APDs
4-APDs
4-APDs
4(6)-APDs
APDs PMT
CASTOR PROTO II
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2004 Test – Beam Results
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CENTAURO RELATED PHENOMENAat Mt Chacaltaya (5200 m) and Pamir (4300 m)
CENTAURO SPECIES:
Abnormal hadron dominance (in N and E), high pT, low multiplicity
● CENTAUROS 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 hadron-rich events
Review: E.G.-D. Phys. Part. Nucl34(2003)285
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STRONGLY PENETRATING CASCADES in Pb CHAMBERSSTRANGELETS?
Cascades pass through the chamber practically without attenuation and revealed many-maxima character with small distances between humps
First observation:Krakow group,17th ICRC, 19812 exotic cascades in Centauro-like event
Other eventsArisawa et al.,Nucl. Phys. B424(1994)241
60 cm Pb~3.6 Λ intEnd of usual hadroniccascade ~1.5 Λint
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Long penetrating hadronic component in CR events
(Strangelet ??)
3.6 λI
3.2 λI
3.6 λI
Hadron 1.5 λI
Hadron
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CENTAURO FIREBALL EVOLUTION
56A + 14N
u, d g s s
QUARK MATTER FIREBALL
in the baryon-rich fragmentation region
High b suppresses production
of (u u) , (d d), allowing for g s s
K+, K0 carry out:
strangeness, positive charge, entropy
CENTRAL COLLISION
at the top of the atmosphere
Ep ~1740 TeV
u, d,s
K+
K 0
(u s)
(d s)
u
s
d
(pre-equilibrium) KAON EMISSION
SQM FIREBALL
EXPLOSION
StrangeletHG
...
HG
B ¼ < 190 MeV B ¼ > 190 MeV
Stabilizing effects of s quarkslong lived state
~75 non strangebaryons+ strangelet
(A ~ 10-15)
Strangenessdistillationmechanism:
C. Greineret al., Phys. Rev. D38
(1988)2797
Estimated for LHC Centauros:
• Energy density ε ~ 3 - 25 GeV/fm 3, • Temperature T ~ 130 - 300 MeV• Baryon chemical potential µb ~ 0.9 - 1.8 GeV/fm3
Possible STRANGELET FORMATION
CNGEN Centauro generator
+Strangelet formation
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Stable strangelet interaction in CASTORMC-algorithm
Strangelet is considered with radius:
Mean interaction path:
Passing through the detector strangelets collide with W nuclei: Spectator part is continuing a passage; Wounded part produces particles in a standard way.
Particles produced in successive interaction points initiate a development of electromagnetic-nuclear cascades. Process ends when strangelet is destroyed.
E. Gładysz, Z. Włodarczyk, J. Phys. G23(1997)2057
31
23223s
str31
0
mμμπ
2a12
A3πArR
231
str03
1
W
NWWstr
ArA1.12π
mAλ
nstrstr NAA'
Code implemented in CMS environment
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MULTIPLICITY in CASTOR’s acceptance
CENTAURO HIJING
Low multiplicity High multiplicity mostly baryons + kaons dominated by pions
Simulations with CNGEN (S. . Sadovsky et al..,Phys. Atom. Nucl. 67(2004)396 )
N = 58 N = 2300
5.3 < < 6.8
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Probability of CENTAURO and STRANGELET detection
1.74cmCASTOR
~70 % of Centauro fireball decay products and substantial part of created strangelets are within CASTOR’s acceptance
Even very high energy strangelets (E ~ 30 TeV) are expected to be produced
5.3 << 6.8T=300 MeV
Ewa Gladysz
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CASTOR
Probability of CENTAURO and STRANGELET detection
CASTOR
� ~65 % of Centauro fireball decay products and substantial part of strangelets are within CASTOR’s acceptance
� Even very high energy strangelets (E ~ 20 TeV) are expected to beproduced
5.3 < < 6.8T=250 MeV
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Simulation results& CASTOR
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HIJING Pb + Pb Event (background)
E ~ 130 TeV ~ 8 TeV/sector
<N> ~ 100/sector
CASTORCASTOR
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Energy distribution in CASTOR
HIJING Strangelet in one sector
Energy in sectors Energy in RU’s Energy in sectors Energy in RU’s
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Strangelet simulations in the CMS environment
(OSCAR)
Geometry configuration:
1 layer: 5 mm W + 2 mm quartz plate ~2.37 X0
1 SU = 7 layers per readout unit
16 (in x 18 (in z) readout channels
Total depth: ~300 X0, 10.5 int
EVEN LOW ENERGY STRANGELETS (~5 TeV) ARE APPARENTLY SEEN ABOVE THE BACKGROUND !
300 X0
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Strangelet identification & Analysis
Strangelet signatures
Azimuthal asymmetryIn energy deposition
Longitudinaltransition curves
sd
iE
EE
Event-by-event analysis Analysis procedure in 2 steps:
average distribution
energy distribution per RU
Large magnitude offluctuations manifestabnormal transition curves
nsfluctuatio
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HIJING + strangelet
HIJING
HIJING+strangelet1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
Transition curves & fluctuations
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Fluctuations in energy distribution
RU’s
Sector containing strangelet
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Analysis results: IEstr = 7,5 TeV Estr = 10 TeV
EM-cutonly H-section
EM+H section
sector containingstrangelet
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Two Stage Construction & Implimentation
STAGE I STAGE II
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STAGE I
STAGE II
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Reducing the number of RU’s16x18 channels 16x9 channels
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Conclusions
● CASTOR is the experimental tool for strangelets ● Strangelet detection through measurement of:
– extreme imbalance between the hadronic and electromagnetic component (multiplicity & energy)
– non-uniform azimuthal energy deposition– penetrating objects beyond the range of normal
hadrons, abnormal longitudinal energy deposition pattern
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CENTAURO I
Observed:Energy ~ 231 TeV 7 cascadesin upper chamber
43 cascades in lower chamber
Lattes,Fujimoto, Hasegawa, Phys. Rep. 65, 151 (1980)
Ohsawa, Shibuya, Tamada, Phys.Rev.D70,074028(2004)
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Energy in CASTOR reading channels
torzID ule sec118 mod1 Continuous numbering schemes:16 x 18 = 256 channels uleztorID mod2 1sec16
HIJING Strangelet
ID2ID1 ID1 ID2
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Analysis results: II
Strangelet in two sectors
Ε1 ~ 3.3TeV
E2 ~ 4 TeV
Estr = 7,5 TeVSectors withstrangelet
~ 14% of strangelets deposit their energy in two sectors
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A=15, E=7.5 TeVA=10, E=5 TeV 60 pions, 1TeV each