Topics
• What are strangelets and nuclearites?
• Ways to detect a cosmic ray strangelet flux
• A strangelet search with AMS-02 on the International Space Station
• A lunar soil strangelet search
• Strangelets beyond the GZK-cutoff ?
Strangelets (Small Lumps of Strange Quark Matter)
Nucleus (12C)
Z=6, A=12
Z/A = 0.5
Strangelet
A=12 (36 quarks)
Z/A = 0.083
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.
Courtesy Evan Finch (Yale)
Quark nuggets as dark matter?
Cosmological nuclearites:
A<1049 (CAUSALITY)A>1040 (EVAPORATION)A>1023Ω3 (NUCLEOSYNTH.)
log(Baryon number)
Q-BALLS are analogous
Q-balls behave like quark nuggetsMadsen, Phys.Rev.Lett. 61(1988)2909 (quark nuggets) Phys.Lett. B246(1990)135 (baryonic Q-balls) Phys.Lett. B435(1998)125 (supersymmetric Q-balls)
Quark nugget pollution in Galaxy => ALL NEUTRON STARS ARE STRANGE STARSQ-ball pollution in Galaxy => ALL NEUTRON STARS ARE Q-STARSOR: FLUXES ARE NEGLIGIBLE
”Ordinary” strangelets• Witten; Farhi & Jaffe…
• Shell-model vs. liquid drop model – Bulk E~A– Surface tension E~A2/3
– Curvature E~A1/3
B=(145 MeV)4
mS=50, 100,… 300 MeV
Madsen, PRD 50 (1994) 3328
Stable
Strangelets have low Z/A
8A1/3
0.1A
Heiselberg, PRD 48 (1993) 1418 [Ordinary strangelets]
0.3A2/3Madsen, PRL 87 (2001) 172003 [CFL]
Nuclei0.5A
Strangelets from strange star binary collisions
• 1 binary ”neutron star” collision per 10,000 years in our Galaxy
• Release of 10-6 solar masses per collision
• Basic assumptions: – SQM absolutely stable!– All ”neutron stars” are strange stars!– All mass released as strangelets with mass A
Strangelet propagation
• Acceleration in supernova shocks etc– Source-flux powerlaw in rigidity
• Diffusion in galactic magnetic field
• Energy loss from ionization of interstellar medium and pion production
• Spallation from collision with nuclei
• Escape from galaxy
• Reacceleration from passing shocks
Cosmic strangelet fluxZ=8, A=138 [CFL]
Rigidity (GV)
Flux (per [year GV sqm sterad]) Source
Interstellar
Solar System
Madsen (2005) Phys.Rev. D 71, 014026
Total CFL-strangelet fluxTotal flux (per [year sqm sterad])
Z
Interstellar
Solar System
No geomagnetic cutoff
Madsen (2005) Phys.Rev. D 71, 014026
Total CFL-strangelet fluxTotal flux (per [year sqm sterad])
A
Interstellar
Solar System
Madsen (2005) Phys.Rev. D 71, 014026
No geomagnetic cutoff
Mass number
Detecting strangelets at 1-1000 GV
Find low Z/A cosmic rays with high precision equipment in space
=>
AMS-02
AMS-02 CollaborationAMS-02 Collaboration
USAA&M FLORIDA UNIV.JOHNS HOPKINS UNIV.MIT - CAMBRIDGENASA GODDARD SPACE FLIGHT CENTERNASA JOHNSON SPACE CENTERUNIV. OF MARYLAND-DEPRT OF PHYSICSUNIV. OF MARYLAND-E.W.S. S.CENTERYALE UNIV. - NEW HAVEN
MEXICO
UNAM
DENMARKUNIV. OF AARHUS
FINLAND
HELSINKI UNIV.UNIV. OF TURKU
FRANCEGAM MONTPELLIERLAPP ANNECYLPSC GRENOBLE
GERMANYRWTH-IRWTH-IIIMAX-PLANK INST.UNIV. OF KARLSRUHE
ITALYASICARSO TRIESTEIROE FLORENCEINFN & UNIV. OF BOLOGNAINFN & UNIV. OF MILANOINFN & UNIV. OF PERUGIAINFN & UNIV. OF PISAINFN & UNIV. OF ROMAINFN & UNIV. OF SIENA
NETHERLANDSESA-ESTECNIKHEFNLR
ROMANIAISSUNIV. OF BUCHAREST
RUSSIAI.K.I.ITEPKURCHATOV INST.MOSCOW STATE UNIV.
SPAINCIEMAT - MADRIDI.A.C. CANARIAS.
SWITZERLANDETH-ZURICHUNIV. OF GENEVA
CHINA BISEE (Beijing)IEE (Beijing)IHEP (Beijing)SJTU (Shanghai)SEU (Nanjing)SYSU (Guangzhou)SDU (Jinan)
KOREA
EWHAKYUNGPOOK NAT.UNIV.
Y96673-05_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 Physicists16 Countries, 56 Institutes, 500 Physicists~ 95% of AMS is constructed in Europe and Asia
Alpha Magnetic Spectrometer AMS-02
PURPOSE
•Cosmic rays•Antimatter (anti-He)•Dark matter•Strangelets•Superconducting magnet technology
International Space Station 2008 - 2011 (or longer)
The AMS superconducting magnet coils are fully assembled:
Volume 35 cu. ft., Field 8,600 Gauss, Weight 2 tons
Detecting strangelets at 100 MeV
Find low Z/A ”nuclei” in lunar dust with high precision accelerator mass
spectrometer
=>
Lunar Soil Strangelet Search
Wright Nuclear Structure LabYale
LSSS-collaboration:Sandweiss, Majka, Finch, Ashenfelter,Chikanian, Han, Heinz, Parker (Yale)Fisher, Monreal (MIT)Madsen (Århus)
Lunar soil flux limits
Baryon number
Flu
x (m
2 s
r yr
) -1
A
Current Preliminary Limit
Goal for Z= 8 (also sensitive to nearby charges)
AMS-01 interesting event
1 event sensitivity in AMS-02 Evan Finch (Yale)
Predicted flux (Madsen 05)
Strangelets could also explain Ultra-High Energy Cosmic Rays
Madsen & Larsen, PRL 90 (2003) 121102
1. Avoids the acceleration problem of ordinary UHECR candidates (HIGH Z)
2. Avoids the GZK cut-off from interaction with 2.7K cosmic microwave background (HIGH A)
AZAZdtdE /low for small / 12
Eliminating the GZK-cutoff
a) Photo-pion production cut-off at
b) Photo-disintegration at
c) Photo-pair-production above
AAmE p eV1020pion-photo
KE 7.2dis /MeV10
KEm 7.2/
Ke Em 7.2pair /2
AAmE p eV1019disdis-photo
AAmE p eV1018pairpair-photo
Summary
• Strangelets have low Z/A• CFL and non-CFL strangelets differ wrt. Z• Experimental verification/falsification of
– Strangelet existence• Realistic from AMS-02 [2008-?]• Possible from lunar soil search [2006-7]
– (A,Z)-relation (CFL or ordinary)• Optimistic, but not impossible from AMS-02 or lunar
soil search
• Possible explanation of UHECR’s• Can play similar games for Q-balls
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