Document

Report
From Colliders to Cosmic Rays
7 – 13 September 2005, Prague, Czech Republic
Search for nuclearites with the
SLIM detector
V. Popa, for the SLIM
Collaboration
Search for Light Monopoles
•Intermediate mass Magnetic Monopoles
• Strange Quark Matter
• Q-balls…
The Collaboration (Bolivia, Canada, Italy, Pakistan):
S.Balestra , S. Cecchini, F. Fabbri , G. Giacomelli, A. Kumar S.
Manzoor , J. McDonald , E. Medinaceli , J. Nogales , L. Patrizii, J.
Pinfold , V. Popa , O. Saavedra, G. Sher , M. Shahzad , M. Spurio,
V. Togo, A. Velarde , A. Zanini
Chacaltaya Cosmic Ray Laboratory
5230 m a.s.l
The experiment
Nuclear track
detectors
Absorber
Total area ~ 440 m2
One module (2424 cm2)
In four years of exposure, for a downgoing flux of particles, the SLIM sensitivity
will be about 10-15cm-2s-1sr-1
Nuclear Track Detectors: CR39 and Makrofol
The track-etch technique
m
Fast Nuclear
MM fragment
CR39
Aluminium
Makrofol
SQM
nuggets
=1 mm
200 A GeV S16+ or
β ~ 10-2 MM
Slow
MM
Calibrations of NTDs
fragments
beam
target
detector foils
detector foils
Z/b =49
In49 158 AGeV
2 faces
Z/b=20
Calibrations of NTDs
Reduced etch rate vs REL
RELREL
vs ßvsfor
nuclearites
ß for
MMs
Makrofol threshold
CR39
Makrofol
CR39 threshold
The search technique
Strong etching (large tracks,
easy to detect)
General scan of the surface
Soft etching
Scan in the predicted position
measurement of REL and
direction of incident particle.
Up to now, no double coincidences found
Strange Quark Matter
E. Witten, Phys. Rev. D30 (1984) 272A. De Rujula, S. L. Glashow, Nature 312 (1984) 734
•Aggregates of u, d, s quarks + electrons , ne= 2/3 nu –1/3 nd –1/3 ns
•Ground state of QCD; stable for 300 < A < 1057
rN  3.5 x 1014 g cm-3
rnuclei  1014 g cm-3
A qualitative picture…
[black points are electrons]
R (fm)
M (GeV)
102
106
103
104
105
106
109
1012
1015
1018
Produced in Early Universe or in strange star collisions (J. Madsen, PRD71 (2005)
014026)
Candidates for cold Dark Matter! Searched for in CR reaching the Earth
Low mass nuclearites (strangelets) in
M (GeV)
- nuclear like
- could be produced as ordinary CR
- could be relativistic
- could be ionized
- cannot reach the Earth surface
- maybe already seen (“Centauro” events…)
d d
us d
s us
u
 300
e
At least two propagation models
allow them to reach the SLIM
atmospheric depth.
Spectator – participant (mass decrease)
(Wilk & Wlodarczyk, Heavy Ion Phys. 4(1986)396
Accretion (mass increase)
S. Banerjee & al., PRL 85 (2000) 1384
Important feature: Z /A « 1
10
3
Nuclei
0.5A
0.3A2/3
8A1/3
~0.1A
Z
10
2
10
10
3
10
4
A
10
5
M. Kasuya et al. Phys.Rev.D47(1993)2153
H.Heiselberg, Phys. Rev.D48(1993)1418
J. Madsen Phys. Rev.Lett.87(2001)172003
10
6
Strangelets : small lumps of SQM
- ~300 < A < 106
-charged
Produced in collisions of strange stars
R. Klingenberg J. Phys. G27 (2001) 475
Accelerated as ordinary nuclei
Mass increase during
propagation => large fluxes
expected at the SLIM altitude
Mass decrease during
propagation => smaller
fluxes expected!
G. Wilk et al. hep-ph/ 0009164 (2000)
J. Madsen et al. Phys.Rev.D71 (2005) 014026
Assuming the “fragmentation” propagation:
Input parameters highly unknown, but expected
 ~ 10
12
15
2 1
10 cm s sr
In the “accretion” scenario, fluxes could be (much) larger (?)
Which is really the lowest A for which strangelets are stable?
1
M (GeV)
31022
High mass nuclearites
d e
u eu d s
s se u
d sd s u
u
d
- Absolutely neutral (all e- inside SQM)
- Could traverse the Earth
- Would produce macroscopic effects
- Non interesting for SLIM (as it would not
reach MACRO sensitivity)
Intermediate mass nuclearites
M (GeV)
1014
e
d e
u eu d s
s se u
d sds u
u
d
- Essentially neutral (most if not all
e- inside
- “Simple” properties: galactic
velocities, elastic collisions,
energy losses…
- Could reach SLIM from above
- Better flux limit from MACRO:
  2  10 16 cm 2s 1sr 1
for
M  1014 GeV
M. Ambrosio et al., Eur.Phys. J. C13 (2000) 453; L. Patrizii, TAUP 2003
Nuclearites - basics
A. De Rújula and S.L. Glashow, Nature 312 (1984) 734
•Typical galactic velocities b  10-3
• Dominant interaction: elastic collisions with atoms in the medium
• Dominant energy losses:
dE
 rmed. v 2
dx
3M / 4r
M  1.5ng (8.4  1014 GeV ) (e inside)

16
2



10
cm
M

1
.
5
ng
(
e
cloud)

2/3
• Phenomenological flux limit from the local density of DM:
  r DM v / 2 M 
 (km2 yr 1 (2sr 1 ))  7.8(1g / M)
Arrival conditions to SLIM
The velocity of a nuclearite
entering in a medium with
v0, after a path L becomes
in the atmosphere:


rmed. ( x )dx
M0
L
v( L)  v 0 e
ratm ( x )  a  e

Hx

b
a = 1.2 10-3 g cm-3; b = 8.6 105 cm; H  50 km
(T. Shibata, Prog. Theor. Phys. 57 (1977) 882.)




r
(
x
)
dx

abe
e

1
atm
0




(h = Chacaltaya altitude, 4275m)
L
H

b
H h
b
Detection conditions in SLIM
preliminary results
About 170 m2 of detectors with an average exposure time of 3.5 years were
analyzed.
Various background tracks (compatible with nuclear recoil fragments
produced by C.R. neutrons) were found.
No candidates found. The present flux 90% C.L. upper limit is
  3.9 10 cm s sr ,
15
2
1
1
for strangelets and nuclearites, but also for fast monopoles and Q-balls.
perspectives
Detector removal from Chacaltaya during fall
Analysis completed by mid 2006
Discovery of IMMs, SQM or Q-balls???
Otherwise, significant limits in not yet explored mass regions!
Nuclearites
White Mt.
Mt. Norikura
Sea level
SLIM
Ohya
MACRO
High altitude:
Underground
SLIM :5300 m White Mountain: 4800 m Mt. Norikura: 2000 m
Ohya : 100 hg/cm2
MACRO : 3700 hg/cm2
Light and intermediate mass MMs
MACRO
SLIM
MACRO
MACRO+SLIM
Charged Q- balls
AKENO, KEK : ground level
ZQ = 1
MACRO : 3700 hg/cm2 undg.
AMS: Space Station
SLIM: 540 g/cm2 atm depth
KEK
AMS
AKENO
SLIM
MACRO
perspectives
Detector removal from Chacaltaya during fall
Analysis completed by mid 2006
Discovery of IMMs, SQM or Q-balls???
Otherwise, significant limits in not yet explored mass regions!
Strong constrains, rejection/confirmation on models of strangelets
production and propagation.

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