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Strangelets: Who is Looking (and how?)

Strangelets: Who is Looking (and how?). Evan Finch Yale University March 29, 2006. Strangelets (Small Lumps of Strange Quark Matter). Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter.

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Strangelets: Who is Looking (and how?)

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  1. Strangelets: Who is Looking (and how?) Evan Finch Yale University March 29, 2006 E. Finch-SQM 2006

  2. Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. That u,d, quark matter is not absolutely stable can be inferred by stability of normal nuclei-but this is not true for u,d,s quark matter. Strangelet A=12 (36 quarks) Z/A = 0.083 Nucleus (12C) Z=6, A=12 Z/A = 0.5 E. Finch-SQM 2006

  3. Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. Stability can not be calculated in QCD, but is addressed in phenomenological models (MIT Bag Model, Color Flavor Locking…). For a large part (~half) of available parameter space, these models predict that SQM is absolutely stable in bulk Values of Bag Constant J. Madsen, PRL 87 (2001) Energy per baryon(MeV) Stable SQM Strange quark mass (MeV) E. Finch-SQM 2006

  4. Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. Bag model results with varying ms values • SQM is less stable for lower baryon number (due curvature energy) for A<~1000 • There are likely significant shell effects at low A. E/A (MeV) A E. Finch-SQM 2006

  5. Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. Potential uses: New chemistry with ‘nuclei’ (strangelets) up to Z~1000 (A~105) Very dense matter available… Terrific QCD laboratory Strangelets can grow by absorbing neutrons – this is an exothermic reaction (~ 20 MeV photon emission) New Energy Source Shaw , Shin, Dalitz, Deasai, Nature, 337, (1989), 436 E. Finch-SQM 2006

  6. Sources of Stable Strangelets? Relics of Early Universe? (Dark Matter?) Probably not… E. Finch-SQM 2006

  7. Sources of Stable Strangelets? Strange Stars If SQM in bulk is stable at zero pressure, all pulsars are likely to be strange stars. Collisions in binary systems would lead to a strangelet component of cosmic ray flux… Experimental limits compiled by R. Klingenberg, SQM ‘00 Flux calculation From J. Madsen, PRD 71,014206 Large uncertainty due to unknowns in input parameters (number of strange star binary systems, fraction of mass ejected, propogation, etc.) Calculated Flux (m2 yr sr)-1 Baryon Number E. Finch-SQM 2006

  8. Experimental limits (for given Z values) Flux (m2 sr yr) -1 Flux predictions from Strange Star collisions ‘Interesting’ events This level of flux relatively unconstrained experimentally A E. Finch-SQM 2006

  9. How to find stable strangelets? • “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS E. Finch-SQM 2006

  10. How to find stable strangelets? • “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS • Superconducting Dipole Magnet: BL2=0.86Tm2 • TOF: 4 layers, t=130ps. Measures Z<13. • Silicon Strip Tracker: 8 double sided layers 8/30 m resolution. Measures Z<25. • Also Rich, ECAL, TRD E. Finch-SQM 2006

  11. How to find stable strangelets? • “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS R~1%  ~10% AMS measurements can easily tell strangelets from normal nuclei over huge energy range (=0.1 up to R=200GeV/c). E. Finch-SQM 2006

  12. How to find stable strangelets? • “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS Flux (m2 sr yr) -1 1 event sensitivity in AMS-02 A Baryon number E. Finch-SQM 2006

  13. How to find stable strangelets? • “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS • AMS STATUS: • AMS scheduled to be fully assembled in 2007 and to arrive at Kennedy Space Center in 2008. • Then? • Potential to have launch by vehicles other than shuttle • Complicated question depending on the space program and ISS utilization Unclear-depends on NASA decisions about shuttle and ISS programs. E. Finch-SQM 2006

  14. How to find stable strangelets? Lunar Soil Search Advantages over terrestrial search: Lunar surface undergoes very little geological mixing and moon has no magnetic fieldgain of ~104 in sensitivity over similar terrestrial search. See talk by Ke Han Further motivation for search: 2 interesting events found in analysis of AMS-01 data. One was measured as Z=8, A=54±7 and is also too slow to be consistent with the geomagnetic cutoff. Would like to follow up on this event. E. Finch-SQM 2006

  15. How to find stable strangelets? Lunar Soil Search Method: use Yale WNSL tandem accelerator as Atomic Mass Spectrometer, and a combination of stopping foil and Silicon detectors to further suppress background. E. Finch-SQM 2006

  16. How to find stable strangelets? Lunar Soil Search Current status: have made 2 short ‘engineering’ runs, now working to improve transmission through machine Flux (m2 sr yr) -1 Current Preliminary Limit AMS-01 interesting event Goal for Z= 8 (also sensitive to nearby charges) A Baryon number E. Finch-SQM 2006

  17. How to find stable strangelets? Terrestrial searches (recent and upcoming) Mueller et. al. (PRL 92, 022501,1994) searched for heavy isotopes of Helium at ~10-8 level using absorption spectroscopy. Z=2 Flux (m2 sr yr) -1 They believe they can improve by several orders of magnitude. Techniques may also be useful for other elements. A Baryon number E. Finch-SQM 2006

  18. How to find stable strangelets? Ongoing search by the SLIM experiment (mountaintop array of CR39 detectors) will be provide better sensitivity for SQM as Dark Matter Terrestrial searches (recent and upcoming) Flux (m2 sr yr) -1 May also be interpereted as relevant for Strange Star flux if strangelets are very penetrating. A See also poster by Xinhua Ma re:upcoming results using L3 cosmic ray triggered events. E. Finch-SQM 2006

  19. How to find stable strangelets? Terrestrial searches (recent and upcoming) • B. Monreal (MIT) is trying to systematically study what best possibilities are for finding terrestrial strangelets (nucl-ex/0506012) relevant to strange star production and has started trying to collect and concentrate various samples for AMS studies. • Some hopeful possibilities are : • Metals in stratosphere (concentrations potentially high, but large samples are hard to get) • Searches among elements with no stable isotopes • Technetium • Radon E. Finch-SQM 2006

  20. How to find stable strangelets? Terrestrial searches (recent and upcoming) Seismic events (consistent with epilinear source interpreted as possible strangelet candidate) have been otherwise explained (PRD 73,043511,2006). E. Finch-SQM 2006

  21. I didn’t talk about… • Accelerator searches • Recent STAR results • CASTOR upcoming E. Finch-SQM 2006

  22. Summary • SQM stability is still an open question. • The AMS detector (if launched) will significantly constrain the stability and production from Strange Star Collisions • Terrestrial, lunar soil searches are active and ongoing and may approach the same level of sensitivity (although for a narrower range of parameter space). E. Finch-SQM 2006

  23. Strangelets: Who is Looking (and how?) Evan Finch Yale University March 29, 2006 E. Finch-SQM 2006

  24. Sources of Stable Strangelets? Relics of Early Universe? (Dark Matter?) Probably not E. Finch-SQM 2006

  25. Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. Stability can not be calculated in QCD, but is addressed in phenomenological models (MIT Bag Model, Color Flavor Locking…). For a large part (~half) of available parameter space, these models predict that SQM is absolutely stable in bulk Energy per baryon number J. Madsen, hep-ph/9809032 E. Finch-SQM 2006

  26. MIT Bag Model Calculations (Fahri and Jaffe) For the set of parameters chosen for this plot, strangelets become more stable then normal nuclear matter for A>100. E/A for nuclear matter E. Finch-SQM 2006

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  28. Potential of Stable Strangelets New chemistry with ‘nuclei’ (strangelets) up to Z~1000 Very dense matter available… Terrific QCD laboratory Strangelets can grow by absorbing neutrons – this is an exothermic reaction (~ 20 MeV photon emission) New Energy Source Shaw , Shin, Dalitz, Deasai, Nature, 337, (1989), 436 Strangelets with A>1017 (R> 5 Angtroms) cannot be supported in the surface of the earth (mg ~ 1 eV/angstrom) Strangelets with M > 2*Msunwill collapse into a blackhole. E. Finch-SQM 2006

  29. Experiments • Skylab, TREK: Satellite based Lexan. No events Z>100 • ARIEL-6, HEAO-3. scintillators, cerenkov counters. No events Z>100 • HECRO-81:Saito et al. scintillator, Cerenkov in balloon at 9gm/cm2. 2 Z=14 undercutoff events. A of 110(370) to be above cutoff(mean rigidity). E/A~.45 GeV • ET event Ichimura et. Al. emulstion chamber in balloon at few g/cm2 but trajectory would have taken it through ~200gm/cm2. Z~30. A measured at 460 • Price monopole. Lexan and emulsions in balloon experiment. Constant ionization through Lexan and low number of delta rays for normal nucleus. One interperetation is Z=45 and mass of 1000-10000 • Centauro (original) • SLIM: mountaintop Lexan CR detector • Fossil Tracks (in meteorites) • Mica: look for tracks traversing 10**7 g/cm2 • Mountaintop. Look for tracks traversing ~600 g/cm2 • Sea Level:tracks traversing 10**3 g/cm2 • Underground: tracks traversing 10**4 g/cm2 • Centauro:1000Tev shower at 500g/cm2, mass~200. Small em component (decay into strange baryons?) and very penetrating (SQM glob which isn’t destroyed by nuclear interactions?) E. Finch-SQM 2006

  30. Some AMS details… • AMS Magnet (ETH-Zurich) superconductor NbTi stabilized by Cu, Al. Cooled by superfluid He connected by thermal bus bar. • TRD (MIT): fleece radiator, straw tube detector with Xe:CO2 gas • Tracker(INFN Perugia) Si sensors ~7x4 cm with pitch 27,100u. 8 planes (1-2-2-2-1) w/ laser alignment • TOF(INFN Bologna)8-8-8-10 scintillator slats (2 planes top,2 bottom) • RICH(INFN Bologna) Aerogel radiator, 680 multianode(4x4) phototubes. Resolution 0.1% • ECAL(INFN-Pisa) Lead-scintillator 648x648x166mm. 9 Superlayers alternate directions of fibers. PMT covers 9x9mm E. Finch-SQM 2006

  31. Color-flavor locked strangelets (J. Madsen) Predicts CFL strangelets have lower E/A than ‘normal’ strangelets, giving a charge/mass relation of Z~0.3A2/3 (“normal” bag model strangelets have Z~.1A for A<<1000 Z~8A1/3 for A>>1000 E. Finch-SQM 2006

  32. AMS-01 E. Finch-SQM 2006

  33. AMS-01 E. Finch-SQM 2006

  34. AMS-01 E. Finch-SQM 2006

  35. R/bg vs bg for z=2 Undercutoff (top) and overcutoff (bot) rigidities, calculated for Z/A=.5

  36. R/bg vs bg for Z>2for (top) undercutoff and (bottom) overcutoff E. Finch-SQM 2006

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  38. International Participation in AMS FINLAND RUSSIA HELSINKI UNIV. UNIV. OF TURKU I.K.I. ITEP KURCHATOV INST. MOSCOW STATE UNIV. DENMARK UNIV. OF AARHUS NETHERLANDS GERMANY ESA-ESTEC NIKHEF NLR RWTH-I RWTH-III MAX-PLANK INST. UNIV. OF KARLSRUHE KOREA USA EWHA KYUNGPOOK NAT.UNIV. A&M FLORIDA UNIV. JOHNS HOPKINS UNIV. MIT - CAMBRIDGE NASA GODDARD SPACE FLIGHT CENTER NASA JOHNSON SPACE CENTER UNIV. OF MARYLAND-DEPRT OF PHYSICS UNIV. OF MARYLAND-E.W.S. S.CENTER YALE UNIV. - NEW HAVEN FRANCE ROMANIA CHINA BISEE (Beijing) IEE (Beijing) IHEP (Beijing) SJTU (Shanghai) SEU (Nanjing) SYSU (Guangzhou) SDU (Jinan) GAM MONTPELLIER LAPP ANNECY LPSC GRENOBLE ISS UNIV. OF BUCHAREST SWITZERLAND ETH-ZURICH UNIV. OF GENEVA TAIWAN SPAIN CIEMAT - MADRID I.A.C. CANARIAS. ITALY ACAD. SINICA (Taiwan) CSIST (Taiwan) NCU (Chung Li) NCKU (Tainan) NCTU (Hsinchu) NSPO (Hsinchu) ASI CARSO TRIESTE IROE FLORENCE INFN & UNIV. OF BOLOGNA INFN & UNIV. OF MILANO INFN & UNIV. OF PERUGIA INFN & UNIV. OF PISA INFN & UNIV. OF ROMA INFN & UNIV. OF SIENA MEXICO UNAM PORTUGAL LAB. OF INSTRUM. LISBON 16 Countries, 56 Institutes, 500 Physicists ~ 95% of AMS is constructed in Europe and Asia Supported by ministries of science/education/energy, space agencies, local goverments and universities Y96673-05_1Commitment

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  46. Strange Quark Matter The existence of hadronic states with more than three quarks is allowed in QCD. The stability of such quark matter has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. Quark Matter Strange Quark Matter Energy Level Strange Quark Mass There is additional stability from reduced Coulomb repulsion. SQM is expected to have low Z/A The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. E. Finch-SQM 2006

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