PowerPoint Presentation - Strange Quark Matter Status and Prospects

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Strangelets Who is Looking (and how?)
Evan Finch Yale University March 29, 2006
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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 A12 (36 quarks) Z/A 0.083
Nucleus (12C) Z6, A12 Z/A 0.5
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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)
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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 Alt1000
• There are likely significant shell effects at low
  A.

E/A (MeV)
A
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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 Z1000 (A105) 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
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Sources of Stable Strangelets?

• Relics of Early Universe? (Dark Matter?)

Probably not
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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
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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
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How to find stable strangelets?

• Best way measure cosmic ray spectrum with high
  precision spectrometerAMS aboard the ISS

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How to find stable strangelets?

• Best way measure cosmic ray spectrum with high
  precision spectrometerAMS aboard the ISS

• Superconducting Dipole Magnet BL20.86Tm2
• TOF 4 layers, ?t130ps. Measures Zlt13.
• Silicon Strip Tracker 8 double sided layers 8/30
  ?m resolution. Measures Zlt25.
• Also Rich, ECAL, TRD

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How to find stable strangelets?

• Best way measure cosmic ray spectrum with high
  precision spectrometerAMS aboard the ISS

?R1 ??? 10
AMS measurements can easily tell strangelets from
normal nuclei over huge energy range (?0.1 up to
R200GeV/c).
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How to find stable strangelets?

• Best way measure cosmic ray spectrum with high
  precision spectrometerAMS aboard the ISS

Flux (m2 sr yr) -1
1 event sensitivity in AMS-02
A
Baryon number
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How to find stable strangelets?

• Best way measure cosmic ray spectrum with high
  precision spectrometerAMS 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.
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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 Z8, A547 and is
also too slow to be consistent with the
geomagnetic cutoff. Would like to follow up on
this event.
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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.
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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
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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.
Z2
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
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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
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 reupcoming results
using L3 cosmic ray triggered events.
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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

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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).
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I didnt talk about

• Accelerator searches
• Recent STAR results
• CASTOR upcoming

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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).

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Strangelets Who is Looking (and how?)
Evan Finch Yale University March 29, 2006
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Sources of Stable Strangelets?

• Relics of Early Universe? (Dark Matter?)

Probably not
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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
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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 Agt100.
E/A for nuclear matter
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Potential of Stable Strangelets

• New chemistry with nuclei (strangelets) up to
  Z1000
• 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 Agt1017 (Rgt 5 Angtroms)
  cannot be supported in the surface of the earth
  (mg 1 eV/angstrom)
• Strangelets with M gt 2Msun will collapse
  into a black hole.

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Experiments

• Skylab, TREK Satellite based Lexan. No events
  Zgt100
• ARIEL-6, HEAO-3. scintillators, cerenkov
  counters. No events Zgt100
• HECRO-81Saito et al. scintillator, Cerenkov in
  balloon at 9gm/cm2. 2 Z14 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. Z30. 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 Z45 and mass of
  1000-10000
• Centauro (original)
• SLIM mountaintop Lexan CR detector
• Fossil Tracks (in meteorites)
• Mica look for tracks traversing 107 g/cm2
• Mountaintop. Look for tracks traversing 600
  g/cm2
• Sea Leveltracks traversing 103 g/cm2
• Underground tracks traversing 104 g/cm2
• Centauro1000Tev shower at 500g/cm2, mass200.
  Small em component (decay into strange baryons?)
  and very penetrating (SQM glob which isnt
  destroyed by nuclear interactions?)

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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 XeCO2 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

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Color-flavor locked strangelets (J. Madsen)
Predicts CFL strangelets have lower E/A than
normal strangelets, giving a charge/mass
relation of Z0.3A2/3 (normal bag model
strangelets have Z.1A for Altlt1000 Z8A1/3 for
Agtgt1000
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AMS-01
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AMS-01
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AMS-01
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• R/bg vs bg for z2
• Undercutoff (top)
• and overcutoff (bot) rigidities, calculated for
  Z/A.5

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R/bg vs bg for Zgt2for (top) undercutoff and
(bottom) overcutoff
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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.
AM 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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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.