1. 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

2. 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…

3. Chacaltaya Cosmic Ray Laboratory 5230 m a.s.l

4. The experiment Total area ~ 440 m 2 One module (24  24 cm 2 ) Absorber Nuclear track detectors 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

5. Nuclear Track Detectors: The track-etch technique CR39 and Makrofol Aluminium CR39 Makrofol  Fast MM Nuclear fragment Slow MM 200 A GeV S 16+ or β ~ 10 -2 MM =1 mm SQM nuggets

6. detector foils target beam fragments Calibrations of NTDs Z/  =20 Z/  =49 2 faces In 49 158 AGeV

7. Calibrations of NTDs CR39 Makrofol CR39 threshold Makrofol threshold REL vs ß for MMs Reduced etch rate vs REL REL vs ß for nuclearites

8. 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

9. Aggregates of u, d, s quarks + electrons, n e = 2/3 n u –1/3 n d –1/3 n s Ground state of QCD; stable for  300 < A < 10 57 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) 10 2 10 3 10 4 10 5 10 6 M (GeV) 10 6 10 9 10 12 10 15 10 18 A qualitative picture… [black points are electrons]  N  3.5 x 10 14 g cm -3  nuclei  10 14 g cm -3

10. Low mass nuclearites (strangelets) in M (GeV)  300 u s d u d 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

11. Important feature: Z /A « 1 M. Kasuya et al. Phys.Rev.D47(1993)2153 H.Heiselberg, Phys. Rev.D48(1993)1418 J. Madsen Phys. Rev.Lett.87(2001)172003 A Z 10 10 2 10 3 0.3A 2/3 ~0.1A 8A 1/3 Nuclei 0.5A 10 3 10 4 10 5 10 6

12. Strangelets : small lumps of SQM - ~300 < A < 10 6 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!

13. Assuming the “fragmentation” propagation: Input parameters highly unknown, but expected In the “accretion” scenario, fluxes could be (much) larger (?) Which is really the lowest A for which strangelets are stable?

14. High mass nuclearites M (GeV) 3  10 22 s e d u u u u u d d d s d s 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)

15. Intermediate mass nuclearites M (GeV) 10 14 s e d u u u u u d d d s d s s s e e e - 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: M. Ambrosio et al., Eur.Phys. J. C13 (2000) 453; L. Patrizii, TAUP 2003

16. 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

17. Arrival conditions to SLIM The velocity of a nuclearite entering in a medium with v 0, after a path L becomes in the atmosphere: 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.) (h = Chacaltaya altitude, 4275m)

18. Detection conditions in SLIM

19. 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 for strangelets and nuclearites, but also for fast monopoles and Q-balls.

20. 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!

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

22. SLIM MACRO MACRO+SLIM Light and intermediate mass MMs

23. AMS KEK AKENO MACRO SLIM Z Q = 1 AKENO, KEK : ground level MACRO : 3700 hg/cm 2 undg. AMS: Space Station SLIM: 540 g/cm 2 atm depth Charged Q- balls

24. 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.