E864: Exotic Nuclei Exotic Nuclei

and Rare ProbesRare Probes

James Nagle Columbia University

for the E864 Collaboration

E864 Collaboration

University of Bari/INFNUniversity of Bari/INFNBrookhaven National LaboratoryBrookhaven National Laboratory

University of California, Los AngelesUniversity of California, Los AngelesUniversity of California, RiversideUniversity of California, Riverside

Columbia UniversityColumbia UniversityIowa State UniversityIowa State University

Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyUnited States Military AcademyUnited States Military AcademyPennsylvania State UniversityPennsylvania State University

Purdue UniversityPurdue UniversityVanderbilt UniversityVanderbilt University

Wayne State UniversityWayne State UniversityYale UniversityYale University

Ken BarishSotiria BatsouliScott CoeRob DaviesPatricia FachiniBrett FademEvan FinchNigel GeorgeRobert HoverstenHazim JaradatJohn LajoieTim MillerMarcello MunhozJames NagleAndrew RoseGene Van BurenZhangbu Xu

Graduate Students

NucleosynthesisShortly after the Big Bang, the universe cooled such that light nuclei such as deuterium, helium and lithium were formed.

Relativistic Heavy Ion Collisions - “Little Bang” Nucleosynthesis

• Source dimension and flow information• Strange baryons available to form HyperNuclei• Antibaryons for AntiNuclei• Exotic Particle Formation (Strange Quark Matter)

Exp

erim

ent

Exp

erim

ent

E86

4 at

th

e B

NL

-AG

S

Au

+ P

t co

llis

ion

s at

11.

6 G

eV/n

ucl

eon

Hig

h r

ate,

mag

net

ic s

pec

trom

eter

d

esig

ned

to

mea

sure

mas

sive

sta

tes

nea

r m

idra

pid

ity

and

low

tra

nsv

erse

m

omen

tum

Transverse Expansion

Slopes show strong mass dependence

Heavier states are more sensitive to density profile and flow parameters

Box profileGaussian profile

A. Polleri et al., nucl-th/9711011

Source Dimensions

Nuclei yields contain source information at

thermal freeze-out, just like HBT.

B3 =

3 He/

p3

W.J.Llope, S.E.Pratt et al., Phys. Rev.C.

NA44 results Pb+Pb S +Pb

“Heavy” Light Nuclei

Penalty per nucleon:

Small Deviations from scaling observed…..

48

1NP

Binding Energy

Correct for spin factor (2J+1) andisospin difference (n/p ~ 1.2).

More tightly bound objects have higher yield….

Exp( BE / 5.8 MeV )

Not the freeze-out temperature.

p

n p

nn

p

deuteron alpha

A = 5 Unstable States

5Li 4He + p (c ~100 fm/c) Preliminary

Close to scaling relation….

AntiDeuterons

Coalescence rate lower for AntiNuclei than

Nuclei?

Predicted if surface emission of antibaryons due to annihilation…..

Preliminary

However… Strange AntiBaryons

pn

p

Not possible

Antideuteron formation

E864 measurement indicates

Y / p = 3.5 1.2

Preliminary

Once p corrected, the coalescence rates agree within errors.

Strange Nucleosynthesis

Calculations for hypernuclei and H-dibaryon assume same transition probability as for normal nuclei !

A.J. Baltz, C. Dover et al., Phys. Lett. B325, 7 (1994). B.A. Cole, M. Moulson, W.A. Zajc, Phys. Lett. B350, 147 (1995).

Testing this assumption to understanding E896, E910, E888, E864…..which assume H coalescence

p

n

deuteronH-dibaryon

is critical

HyperNuclei Mass Distribution

Invariant Mass (GeV)

Sampled 9.5 billion central Au+Pt interactions

Preliminary analysis of 2/3 of data sample shown here

Branching Fraction 25%

Signal observed at the 1.8 sigma level….

3H 3He + -

3H 3He + -

Lower Transition Rate ?

Check transition rate by measuring ingredients and resulting states.

E891E864

Compare:

In same region in phase space.

np

H3

npp

He

3= 0.162 0.088

Preliminary

Strange Quark MatterSQM = many quarks in a color-singlet configuration

d

s

d

d

d

d

u

uu

u

us

s

s

Null Result….

10-8 to 10-9

For SQM > 50 ns

E878E886

E864 (PRL)

E864 Final

T.A. Armstrong et al., Phys. Rev. Lett. 79, 3612 (1997).T.A. Armstrong et al., Nucl. Phys. A 625, 494 (1997).T.A. Armstrong et al., Phys. Rev. C, R1829 (1999).

SQM Implications

Coalescence Predictions

Plasma Predictions

E864 Final Limits Z = +2

Plasma Distillation

Many predictions ruled out, but calculations are not precise.

Strange Coalescence

Sensitive to:

A = 6-7 and |S| = 2-3

However, must consider hypernuclei measurement…….

Conclusions

• Measurements over 10 orders of magnitude in yield

• Light Nuclei Scaling and Deviations

• Strange Antibaryon Enhancement and AntiNuclei Yields

• Penalty for HyperNuclei

• Strange Quark Matter < 10-9

Binding Energy in Thermal Model

N

n

Z

pTE

A

AAA

dp

Nd

dp

Nde

V

s

Apd

Nd

3

3

3

3/

13

3

30

)2(

2

12

)(

Fit results to a thermal temperatureon the order of 50 MeV which is quite low; however flow has not beenaccounted for at this point and measurements are at low pt.

Strange AntiBaryonsTarget

Incoming Au beam

p