Date post: | 30-Dec-2015 |
Category: |
Documents |
Upload: | dexter-kennedy |
View: | 51 times |
Download: | 2 times |
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
Outline
● CASTOR detector description● Motivation & Physics● Experimental data & model description of
strangelets● Monte Carlo results (CNGEN, HIJING)● Simulations results & CASTOR● Strangelet analysis● Summary
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)
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
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
EM - PROTOTYPE W-PLATES + Q-
FIBRE / PLATES
~ 20 Xo
H CASTOR A L
CASTOR PROTO BEAM TEST 2003
5mm W + 2mm Q H
3mm W + 1.5mm Q EM
Octant
Semi-Octant
CASTOR PROTO II
4-APDs
4-APDs
4-APDs
4-APDs
4(6)-APDs
APDs PMT
CASTOR PROTO II
2004 Test – Beam Results
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
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
Long penetrating hadronic component in CR events
(Strangelet ??)
3.6 λI
3.2 λI
3.6 λI
Hadron 1.5 λI
Hadron
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
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
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
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
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
Simulation results& CASTOR
HIJING Pb + Pb Event (background)
E ~ 130 TeV ~ 8 TeV/sector
<N> ~ 100/sector
CASTORCASTOR
Energy distribution in CASTOR
HIJING Strangelet in one sector
Energy in sectors Energy in RU’s Energy in sectors Energy in RU’s
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
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
HIJING + strangelet
HIJING
HIJING+strangelet1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
Transition curves & fluctuations
Fluctuations in energy distribution
RU’s
Sector containing strangelet
Analysis results: IEstr = 7,5 TeV Estr = 10 TeV
EM-cutonly H-section
EM+H section
sector containingstrangelet
Two Stage Construction & Implimentation
STAGE I STAGE II
STAGE I
STAGE II
Reducing the number of RU’s16x18 channels 16x9 channels
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
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)
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
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
A=15, E=7.5 TeVA=10, E=5 TeV 60 pions, 1TeV each