Search for nuclearites with the SLIM detector V. Popa, for the SLIM Collaboration From Colliders to Cosmic Rays 7 – 13 September 2005, Prague, Czech Republic Search for Light Monopoles
Dec 17, 2015
Search for nuclearites with the SLIM detector
V. Popa, for the SLIM Collaboration
From Colliders to Cosmic Rays 7 – 13 September 2005, Prague, Czech Republic
Search for Light Monopoles
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
•Intermediate mass Magnetic
Monopoles
• Strange Quark Matter
• Q-balls…
The experiment
Total area ~ 440 m2 One module (2424 cm2)
Absorber
Nuclear track detectors
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:
The track-etch technique
CR39 and Makrofol
Aluminium
CR39
Makrofol
Fas
t MM
Nuclear fragment
Slow MM
200 A GeV S16+ or β ~ 10-2 MM
=1 mm
SQMnuggets
detector foils detector foils
target
beam
fragments
Calibrations of NTDs
Z/=20
Z/=49
2 faces
In49 158 AGeV
Calibrations of NTDs
CR39 Makrofol
CR39 threshold
Makrofol threshold
REL vs ß for MMs
Reduced etch rate vs REL REL vs ß for nuclearites
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
•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
Strange Quark Matter E. Witten, Phys. Rev. D30 (1984) 272A. De Rujula, S. L. Glashow, Nature 312 (1984) 734
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
R (fm) 102 103 104 105 106
M (GeV) 106 109 1012 1015 1018
A qualitative picture…
[black points are electrons]
N 3.5 x 1014 g cm-3
nuclei 1014 g cm-3
Low mass nuclearites (strangelets) in M (GeV)
300
u sd
u sud
d
s
e
- nuclear like- could be produced as ordinary CR- could be relativistic- could be ionized- cannot reach the Earth surface- maybe already seen (“Centauro” events…)
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
M. Kasuya et al. Phys.Rev.D47(1993)2153 H.Heiselberg, Phys. Rev.D48(1993)1418J. Madsen Phys. Rev.Lett.87(2001)172003
A
Z
10
102
103
0.3A2/3
~0.1A8A1/3
Nuclei 0.5A
103
104
105
106
Strangelets : small lumps of SQM - ~300 < A < 106 Produced in collisions of strange stars
R. Klingenberg J. Phys. G27 (2001) 475
-charged Accelerated as ordinary nuclei
G. Wilk et al. hep-ph/ 0009164 (2000)J. Madsen et al. Phys.Rev.D71 (2005) 014026
Mass increase during propagation => large fluxes expected at the SLIM altitude
Mass decrease during propagation => smaller fluxes expected!
Assuming the “fragmentation” propagation:
Input parameters highly unknown, but expected 1121512 1010~ srscm
In the “accretion” scenario, fluxes could be (much) larger (?)
Which is really the lowest A for which strangelets are stable?
High mass nuclearitesM (GeV)
31022
s e
du
uuu
u
dd
d s
ds
s s
e e
- 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 nuclearitesM (GeV)
1014 s e
du
u uu
u
dd
d s
ds
s s
e ee
- 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:
GeV10Mforsrscm102 1411216
M. Ambrosio et al., Eur.Phys. J. C13 (2000) 453; L. Patrizii, TAUP 2003
Nuclearites - basics
•Typical galactic velocities 10-3
• Dominant interaction: elastic collisions with atoms in the medium• Dominant energy losses:
• Phenomenological flux limit from the local density of DM:
A. De Rújula and S.L. Glashow, Nature 312 (1984) 734
)M/g1(8.7))sr2(yrkm( 112
)cloude(ng5.1Mcm10
)insidee()GeV104.8(ng5.1M4/M3216
143/2
2
.medv
dxdE
MDM 2/v
Arrival conditions to SLIM
ev)L(v0
L
0
.meddx)x(
M
The velocity of a nuclearite entering in a medium with v0, after a path L becomes
in the atmosphere:
a = 1.2 10-3 g cm-3; b = 8.6 105 cm; H 50 km
(T. Shibata, Prog. Theor. Phys. 57 (1977) 882.)
ea)x(atm
bxH
1)(0
b
hH
b
HL
atm eabedxx(h = Chacaltaya altitude, 4275m)
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
,109.3 11215 srscmfor 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
High altitude: SLIM :5300 m White Mountain: 4800 m Mt. Norikura: 2000 m
Underground Ohya : 100 hg/cm2 MACRO : 3700 hg/cm2
SLIM
Sea level
White Mt.
Mt. Norikura
Ohya
MACRO
AMS
KEK
AKENO
MACROSLIM
ZQ = 1
AKENO, KEK : ground level
MACRO : 3700 hg/cm2 undg.
AMS: Space Station
SLIM: 540 g/cm2 atm depth
Charged Q- balls