Strangelets and nuclearites—an overview

Jes Madsen

University of Aarhus, Denmark

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)

E/A for bulk strange quark matter

E/A(MeV)

Phase diagram for QCD

Temperature

Density

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

B = (145MeV)4 vs. (165MeV)4

Unstable

Stable

Color-Flavor Locking

Madsen, PRL 87 (2001) 172003

Stable

MeV100

BULK STRANGELETS

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

Atlantis launchSep. 9, 2006

ISS from STS-115Sep. 17, 2006

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

Courtesy Choutko (MIT)

Detecting strangelets at 100 MeV

Find low Z/A ”nuclei” in lunar dust with high precision accelerator mass

spectrometer

=>

Lunar Soil Strangelet Search

The Moon as a strangelet detector

NASA gave us 15 grams of lunar soil from Apollo 11

Wright Nuclear Structure LabYale

LSSS-collaboration:Sandweiss, Majka, Finch, Ashenfelter,Chikanian, Han, Heinz, Parker (Yale)Fisher, Monreal (MIT)Madsen (Århus)

Courtesy Evan Finch (Yale)

Courtesy Evan Finch (Yale)

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)

Cronin, Gaisser & Swordy (1997)

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