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OMEG-10, Osaka (Japan), March 8th-10th, 2010 Christoph Scheidenberger (GSI)

Storage-ring experiments for nuclear astrophysics at GSI

Facility overview

Experimental opportunities

Future directions

Emphasis on data for nuclear astrophysics:

Christoph Scheidenberger

and

• decay spectroscopy• mass measurements• reaction studies• half-lives


Neutron number

Pro

ton

num

ber

Terra I

ncogni

ta

Fe

r-processrp-

proce

ss

s-proc

ess Nucleosynthesisin supernovae

Nucleosynthesis in binary systems

Nucleosynthesis of the chemical elements

Fusion up to iron

Big Bang nucleosynthesis

p-proc

ess

Heavy nuclei (A>56) are mainly produced by s-process (~50%) and r-process (~50%)

Nucleosynthesisin AGB stars


The need for reliable nuclear physics data

Consistent nuclear theory and/or experimental data needed!

G. Martinez-Pinedo et al., priv. comm


Nuclear astrophysics in the laboratory

SIS

FRS

ESR

SHE, masses,decay properties

half-lives, level energies,β-delayed n-emission

LAND / R3Bphoto-dissociation rates,(n,γ), (p,γ) cross sections, B(GT)

SHIP-Trap

masses, half-lives, (p,γ) rates, B(GT)

Theorynuclear rates, nucleosynthesis


Nuclear astrophysics in the laboratory

SIS

FRS

ESR

SHE, masses,decay properties

half-lives, level energies,β-delayed n-emission

LAND / R3Bphoto-dissociation rates,(n,γ), (p,γ) cross sections, B(GT)

SHIP-Trap

masses, half-lives, (p,γ) rates, B(GT)

Theorynuclear reaction rates, nucleosynthesisnetwork calculations


Elementary reactions for the production of exotic nuclei

1GeV/u U + HExperimental data:

V Ricciardi et al., PRC 73 (2006) 014607


Production of very neutron-rich isotopes

~1GeV/u Au + Be

J. Benlliure et al., NPA 660 (1999) 87

Cold fragmentation Fission Fragmentation

Theory

Experiment}}

~1GeV/u U + Pb~1GeV/u U + Be

H. Alvarez et al., Eur. Phys. J. A (2009)J. Benlliure et al., Eur. Phys. J. ST 150 (2007) 309J. Benlliure et al., NPA 660 (1999) 87

H. Alvarez et al., Eur. Phys. J. A (2009)and to be published

M. Bernas et al., Phys. Lett.


Spectroscopy and ß-decay studies at FRS

A. Jungclaus et al., PRL 99, 132501 (2007)

F.Nowacki, H.Grawe,G.Martínez-Pinedo

8+ Isomer in 130Cd

Qβ-measurement (I. Dillmann et al., PRL91, 162503 (2003) )130Cd less bound than expected "quenching" of N=82 shell closure?

Detailed spectroscopy, unambigous identification, high granularity, high γ-efficiencyno indication of "shell quenching", no weakening of N=82-shell observedAgreement with SM-calculations:• level sequence• energies• transition rates


Storage, cooling, measurement

Stochastic and electron cooling

Schottky-noise detection

Storage times: min. .... days

Rel

ativ

e m

omen

tum

spre

adδp

/p

0 1 2 3 4 time [s]

Fast injectionof fragments(bunch~400ns)


Storage, cooling, measurement

Revolution-frequency measurement

Mass determination

Mass accuracy 5 ·10-8 up to 5 ·10-7Masses of more than 1100 nuclides measuredResults: ~ 350 new mass values

~ 300 improved mass values

Fast injectionof fragments(bunch~400ns)


T9=1,4nn=3·1020cm-3

FRS-ESR dataETFSI-Q

Mass number A

Rel

ativ

e ab

unda

nce

HFB (BSk2)

0 MeV- 0.5 MeV

0.5 MeV1.0 MeV1.5 MeV2.0 MeV> 2.0 MeV

- 1.0 MeV- 1.5 MeV- 2.0 MeV< - 2.0 MeV

m(e

xp)-

m(th

eory

)

50

82

82

126

5028

S. Goriely, et al., Phys. Rev. C66 (2002) 024326

σrms = 650 keV

Example:Mapping the mass surface: predictive power of mass models

In explosive szenarios (Novae, X-ray bursts, and SN) masses play a crucial role• energy "generation" ( light curves)• pathways ( final abundances)

Few data exist• mass models ( predictive power?)

H. Geissel, B.Pfeiffer, et al., AIP Conf. Proc. Vol. 831 (2006) 108


β−- decay to bound states of the released electron

New radioactive decay modePrediction: R. Daudel, Rev. Sci. Instr. 85, 162 (1947)First experimental observation at ESR: 163Dy/Ho66+M. Jung et al., PRL 69, 2164 (1992)

ApplicationsNeutrino mass Galactic age

187Re/Os cosmochronometer

K. Takahashi et al., Tours Symposium on Nuclear Physics III,AIP Conf. Proc. 425(1), 616 (1998)

F. Bosch et al., PRL 77,5190 (1996)

F. Bosch, Phys. Scripta T59, 221 (1995)

TG = (15 ± 1) Gamν < 265 eV


Time-resolved decay studies: bound-state beta decay

207Pb81+

207mTl81+

207Tl81+

T. Ohtsubo et al., PRL 95, 052501 (2005)


K. Takahashi,K. Yokoi, ADNDT 36 (1987)

Theory

Experiment

Branching ratio λβb/λβc

Z=81

T. Ohtsubo et al., PRL 95, 052501 (2005)

Decay rate of continuum beta decay:

Decay rate of bound-state beta decay:

Branching ratio: for allowed transitions:

∫ −=0

10

20 )(),()(

W

ii dWWSWZFWWpWfwith∑=i

iii

β fMgλ

c

23

2

2π

∑ Ψ=i

kkei

ik qRMgλbβ

2,

2)(23

2)( )(

22 νπ

π

1)( ≡WSi

λβb / λβc

Calculation0,171 ± 0,001

Experiment0,188 ± 0,018

f(Z,W)q(R)Ψ

λλ ν

K

β

β e

c

b

22

~


Isomer decays are altered: half-life measurement of bare 151mEr68+

Frequency / Hz - 60080000

Noi

sepo

werd

ensit

y

Time / s

2.6 MeV

77400 77600 77800

0

100

200150

50

Yu. A. Litvinov et al., Phys. Lett. B 573, 80 (2003)

Decay rate for bare ions


Newly observed decay-properties in H-like iodine

• Orbital electron capture of highly-charged exotic ions• exhibits modulated exponential behaviour• explanation presently under discussion

Fit: dNEC/dt = N0 λEC exp(-λt) [1 + a cos(ωt + φ)]


Origin of ‘p-nuclei’ – abundant n-deficient isotopes, e.g. 92,94Mo, 96,98Ru

Supernova shockpassing throughO-Ne layers of progenitor star Arnould & Goriely Phys. Rep. 384,1 (2003)


(p,γ) or (α,γ) rates in the Gamow window of the p-process in inverse kinematics

Pilot experiment performed with stable beams:• direct proton capture of 96Ru in H gas target: 96Ru(p,γ)97Rh• in-ring particle detectors for recoiling reaction products (low background, high efficiency)

measurementsGamow w.

R. Reifarth, M. Heil, P. Woodsto be published


Scattering of stored exotic nuclei off light hadronic probes

• Inverse kinematics• thin gas target (~1015/cm2)• kinematic complete measurements

– elastic scattering (p,p) …– inelastic scattering (p,p’), (α,α’) ...– charge-exchange reactions (p,n), (3He,t), (d,2He) …– quasi-free scattering (p,pn), (p,2p), (p, pα) …

Excitation energy and form factorsfrom recoil ions with small energy/small momentum

Feasibility study (p,p) with350 MeV/u 136Xe ions in ESR

S. Ilieva et al.,Eur. Phys. J. Special Topics 150, 357–358 (2007)

Nuclear matter radius: Rm = 4.89 (10) fm

10 cm

Gas jet

Heavy ions

Neutrons /Charged Ejectiles

UHV

Scintillat

or


Summary and conclusion

Experimental data are needed for stellar nucleosynthesis

These data can be obtained (to some extent) in the laboratory,

Storage ring is a unique instrument,experiments provide data for highly-charged ions

Complementary approaches exist...– exotic nuclei at low and high energies– spectroscopy– reaction studies (stable and secondary beams FAIR)

...which yield– masses, half-lives, Pnn-values, fission yields, cross sections, etc. .....

...needed to understand the state of affairs

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