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 m 2 One module (24  24 cm 2 )

In four years of exposure, for a downgoing flux of particles, the SLIM sensitivity will be about 10 -15 cm -2 s -1 sr -1

Nuclear Track Detectors:

The track-etch technique

CR39 and Makrofol

=1 mm

200 A GeV S 16+ or β ~ 10 -2 MM CR39 Aluminium Makrofol

m

Fast MM Nuclear fragment Slow MM SQM nuggets

Calibrations of NTDs

fragments

target detector foils detector foils Z/

b

=49

In 49 158 AGeV beam 2 faces

Z/

b

=20

Calibrations of NTDs

Reduced etch rate vs REL

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 , n e = 2/3 n u • Ground state of QCD ; stable for  300 < A < 10 57 –1/3 n d –1/3 n s r N  r nuclei 3.5 x 10 14 g cm -3  10 14 g cm -3 A qualitative picture… [black points are electrons] R (fm) 10 2 M (GeV) 10 6 10 3 10 9 10 4 10 12 10 5 10 15 10 6 10 18 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)  300 s d d u s u u s d - nuclear like - could be produced as ordinary CR could be relativistic could be ionized - cannot reach the Earth surface - maybe already seen (“Centauro” events…) 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

Z 10 3

Nuclei 0.5A

8A 1/3 0.3A

2/3 ~0.1A

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 < 10 6 -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 G. Wilk et al. hep-ph/ 0009164 (2000) J. Madsen et al. Phys.Rev.D71 (2005) 014026 Mass decrease during propagation => smaller fluxes expected!

Assuming the “ fragmentation ” propagation: Input parameters highly unknown, but expected  ~ 10  12  10  15

cm

 2

s

 1

sr

 1 In the “ accretion ” scenario, fluxes could be (much) larger (?) Which is really the lowest A for which strangelets are stable?

M (GeV) 3  10 22

High mass nuclearites

u s d u s e d u s e d e s d d s u u - 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) 10 14 e u s d u s e d u s e d s d e d s u u - 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  2 s  1 sr  1 for M  10 14 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 • Dominant interaction: elastic collisions with atoms in the medium • Dominant energy losses: b  10 -3 dE   r med .

v 2 dx     3 M / 4 r  2 / 3 M  1 .

5 ng ( 8 .

4  10 14 GeV )   10  16 cm 2 M  1 .

5 ng ( e  inside ) ( e  cloud ) • Phenomenological flux limit from the local density of DM:   r

DM

v /  2 

M

  ( km  2 yr  1 ( 2  sr  1 ))  7 .

8 ( 1 g / M )

Arrival conditions to SLIM

The velocity of a nuclearite entering in a medium with v 0 , after a path L becomes in the atmosphere: v ( L ) r atm ( x )  a   e  b   M v 0 e H  x 0 L  r med .

( x ) dx a = 1.2  10 -3 g cm -3 ; b = 8.6  10 5 cm; H  50 km (T. Shibata, Prog. Theor. Phys.

57

(1977) 882.)

L

 0 r

atm

(

x

)

dx



abe



H b

 

e H b



h (h = Chacaltaya altitude, 4275m)

 1  

Detection conditions in SLIM

preliminary results

About 170 m 2 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  15

cm

 2

s

 1

sr

 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

SLIM

White Mt.

Mt. Norikura

Sea level

Ohya MACRO High altitude: SLIM :5300 m White Mountain: 4800 m Mt. Norikura: 2000 m Underground Ohya : 100 hg/cm 2 MACRO : 3700 hg/cm 2

Light and intermediate mass MMs

SLIM MACRO MACRO MACRO+SLIM

KEK AMS AKENO SLIM MACRO

Charged Q- balls Z Q = 1 AKENO, KEK : ground level MACRO : 3700 hg/cm 2 undg.

AMS: Space Station SLIM: 540 g/cm 2 atm depth

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.