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…

Chacaltaya Cosmic Ray Laboratory

5230 m a.s.l

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)

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

,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

SLIM

MACRO

MACRO

MACRO+SLIM

Light and intermediate mass MMs

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

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 strangeletsproduction and propagation.