1. CASTOR Centauro And Strange Object Research
Strangelet hunt at CMS
Panos Katsas
University 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/

2. Outline CASTOR detector description Motivation & Physics
Experimental data & model description of strangelets
Monte Carlo results (CNGEN, HIJING)
Simulations results & CASTOR
Strangelet analysis
Summary

3. 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)

4. Detectors near beamline: Forward Physics in p+p, p+A, A+A
Hermetic coverage up to |h| ~ 6.6
Zero degree neutral energy
Physics: Centrality, Low-x, Limiting fragmentation, Strangelets, DCC
140 m
CASTOR

5. CMS Very-Forward Region
Option 2 (preferred)
CMS Very-Forward Region HF
T2 Tracker
5.32 <  < 6.71
3 <  < 5.3
CASTOR
5.31 <  < 6.84
Inner radius ~ 38 mm
Outer radius ~ 135 mm active
Outer radius ~ 280 mm total

6. EM - PROTOTYPE W-PLATES + Q-FIBRE / PLATES
H CASTOR A L
~ 20 Xo

7. CASTOR PROTO BEAM TEST 2003

8. 5mm W + 2mm Q H
Octant
3mm W + 1.5mm Q EM
Semi-Octant
CASTOR PROTO II

9. CASTOR PROTO II
4(6)-APDs
4-APDs
4-APDs
4-APDs
4-APDs
APDs PMT

10. 2004 Test – Beam Results

11. cascades, clusters, halos, frequently accompanying hadron- rich events
CENTAURO RELATED PHENOMENA at 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 ~ 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

12. STRONGLY PENETRATING CASCADES in Pb CHAMBERS STRANGELETS?
First observation:
Krakow group,17th ICRC, 1981
2 exotic cascades in Centauro-like event
Other events
Arisawa et al.,Nucl. Phys.
B424(1994)241
End of usual hadronic
cascade ~1.5 Λint
60 cm Pb~3.6 Λ int
Cascades pass through the chamber practically without attenuation and revealed many-maxima character with small distances between humps

13. (Strangelet ??) Long penetrating hadronic component in CR events

14. Estimated for LHC Centauros:
Energy density
ε ~ GeV/fm 3,
Temperature
T ~ MeV
Baryon chemical potential
µb ~ GeV/fm3
Possible STRANGELET FORMATION
CNGEN
Centauro generator +
Strangelet formation

15. Stable strangelet interaction in CASTOR MC-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
Code implemented in CMS environment

16. 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 )
5.3 <  < 6.8

17. Probability of CENTAURO and STRANGELET detection
T=300 MeV
5.3 << 6.8
CASTOR
Ewa Gladysz
~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

18. Probability of CENTAURO and STRANGELET detection
T=250 MeV
5.3 <  < 6.8
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

19. Simulation results & CASTOR

21. HIJING Pb + Pb Event (background)
<N> ~ 100/sector
E ~ 130 TeV
~ 8 TeV/sector
CASTOR
CASTOR

22. Energy distribution in CASTOR
Energy in sectors
Energy in RU’s
Energy in sectors
Energy in RU’s
HIJING
Strangelet in one sector

23. 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 Λint
EVEN LOW ENERGY STRANGELETS (~5 TeV) ARE APPARENTLY SEEN ABOVE THE BACKGROUND !
300 X0

24. Results for finer sampling of the geometry
12 TeV
9 TeV

25. Strangelet identification & Analysis
Event-by-event analysis
Analysis procedure in 2 steps:
Strangelet signatures
Azimuthal asymmetry
In energy deposition
Longitudinal
transition curves
energy distribution per RU
average distribution
Large magnitude of
fluctuations manifest
abnormal transition curves

26. HIJING + strangelet 1 2 3 4 HIJING+strangelet 5 6 7 8 9 10 11 1216 13 14 15
Transition curves & fluctuations

27. Fluctuations in energy distribution
RU’s
Sector containing strangelet

28. Analysis results: I sector containing strangelet EM+H section EM-cut
Estr = 10 TeV
Estr = 7,5 TeV
sector containing
strangelet
EM+H section
EM-cut
only H-section

29. Two Stage Construction & Implimentation
STAGE I
STAGE II

30. STAGE I
STAGE II

31. Reducing the number of RU’s
16x18 channels
16x9 channels

32. 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

33. CENTAURO I Observed: Energy ~ 231 TeV 7 cascades in upper chamber
Lattes,Fujimoto, Hasegawa,
Phys. Rep. 65, 151 (1980)
Observed:
Energy ~ 231 TeV
7 cascades
in upper chamber
43 cascades
in lower chamber
Ohsawa, Shibuya, Tamada, Phys.Rev.D70,074028(2004)

34. Energy in CASTOR reading channels
Continuous numbering schemes:
16 x 18 = 256 channels
ID2
ID1
ID1
ID2
HIJING
Strangelet

35. Analysis results: II
~ 14% of strangelets deposit their energy in two sectors
Estr = 7,5 TeV
Sectors with
strangelet
Strangelet in two sectors
Ε1 ~ 3.3TeV
E2 ~ 4 TeV

36. A=15, E=7.5 TeV
A=10, E=5 TeV
60 pions, 1TeV each