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

E. Finch-SQM 2006 Strangelets (Small Lumps of Strange Quark Matter) Nucleus ( 12 C) Z=6, A=12 Z/A = 0.5 Strangelet A=12 (36 quarks) Z/A = 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. Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter.

E. Finch-SQM 2006 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) Stable SQM Energy per baryon(MeV) Strange quark mass (MeV)

E. Finch-SQM 2006 Strangelets (Small Lumps of Strange Quark Matter) Roughly equal numbers of u,d,s quarks in a single ‘bag’ of cold hadronic matter. 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 Bag model results with varying m s values

E. Finch-SQM 2006 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~10 5 ) 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 Sources of Stable Strangelets? Relics of Early Universe? (Dark Matter?) Probably not…

E. Finch-SQM 2006 Sources of Stable Strangelets? 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… Strange Stars Calculated Flux (m 2 yr sr) -1 Baryon Number Flux calculation From J. Madsen, PRD 71, Experimental limits compiled by R. Klingenberg, SQM ‘00 Large uncertainty due to unknowns in input parameters (number of strange star binary systems, fraction of mass ejected, propogation, etc.)

E. Finch-SQM 2006 Flux predictions from Strange Star collisions Experimental limits (for given Z values) ‘Interesting’ events Flux (m 2 sr yr) -1 A This level of flux relatively unconstrained experimentally

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

E. Finch-SQM 2006 How to find stable strangelets? “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS Superconducting Dipole Magnet: BL 2 =0.86Tm 2 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 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 How to find stable strangelets? “Best” way: measure cosmic ray spectrum with high precision spectrometer…AMS aboard the ISS Baryon number 1 event sensitivity in AMS-02 Flux (m 2 sr yr) -1 A

E. Finch-SQM 2006 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 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 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 ~10 4 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 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 How to find stable strangelets? Lunar Soil Search Current status: have made 2 short ‘engineering’ runs, now working to improve transmission through machine Baryon number Flux (m 2 sr yr) -1 A Current Preliminary Limit Goal for Z= 8 (also sensitive to nearby charges) AMS-01 interesting event

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

E. Finch-SQM 2006 How to find stable strangelets? Terrestrial searches (recent and upcoming) Ongoing search by the SLIM experiment (mountaintop array of CR39 detectors) will be provide better sensitivity for SQM as Dark Matter A See also poster by Xinhua Ma re:upcoming results using L3 cosmic ray triggered events. Flux (m 2 sr yr) -1 May also be interpereted as relevant for Strange Star flux if strangelets are very penetrating.

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

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

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

E. Finch-SQM 2006 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/

E. Finch-SQM 2006 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

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>10 17 (R> 5 Angtroms) cannot be supported in the surface of the earth (mg ~ 1 eV/angstrom) Strangelets with M > 2*M sun will collapse into a black hole.

E. Finch-SQM 2006 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 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 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 ( ) w/ laser alignment TOF(INFN Bologna) 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 Color-flavor locked strangelets (J. Madsen) Predicts CFL strangelets have lower E/A than ‘normal’ strangelets, giving a charge/mass relation of Z~0.3A 2/3 (“normal” bag model strangelets have Z~.1A for A<<1000 Z~8A1/3 for A>>1000

E. Finch-SQM 2006 AMS-01

E. Finch-SQM 2006 AMS-01

E. Finch-SQM 2006 AMS-01

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

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

E. Finch-SQM 2006

International Participation in AMS USA 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 MEXICO UNAM DENMARK UNIV. OF AARHUS FINLAND HELSINKI UNIV. UNIV. OF TURKU FRANCE GAM MONTPELLIER LAPP ANNECY LPSC GRENOBLE GERMANY RWTH-I RWTH-III MAX-PLANK INST. UNIV. OF KARLSRUHE ITALY 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 NETHERLANDS ESA-ESTEC NIKHEF NLR ROMANIA ISS UNIV. OF BUCHAREST RUSSIA I.K.I. ITEP KURCHATOV INST. MOSCOW STATE UNIV. SPAIN CIEMAT - MADRID I.A.C. CANARIAS. SWITZERLAND ETH-ZURICH UNIV. OF GENEVA CHINA BISEE (Beijing) IEE (Beijing) IHEP (Beijing) SJTU (Shanghai) SEU (Nanjing) SYSU (Guangzhou) SDU (Jinan) KOREA EWHA KYUNGPOOK NAT.UNIV. Y _1Commitment PORTUGAL LAB. OF INSTRUM. LISBON ACAD. SINICA (Taiwan) CSIST (Taiwan) NCU (Chung Li) NCKU (Tainan) NCTU (Hsinchu) NSPO (Hsinchu) TAIWAN 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

E. Finch-SQM 2006

Strange Quark Matter The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have low Z/A 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. Strange Quark Mass Quark MatterStrange Quark Matter Energy Level