Nuclear astrophysics research in ATOMKI

György Gyürky

Institute of Nuclear Research (ATOMKI)

Debrecen, Hungary

NuPECC meeting, October 7-8, 2011, Budapest, Hungary

2

Research activities of the nuclear astrophysics group of ATOMKI

Experiments for the astrophyical p-process

Study of the electron screening effect

Half-life measurements relevant to astrophysics

RIB experiments relevant to astrophysics

Application of the Trojan Horse

indirect method

7Be isotope productionfor nuclear astrophysics

experiment

Underground experiments:low cross section measurements

(LUNA collaboration)

etc...

• nucleosynthesis• experiments in ATOMKI

• energy generation• experiments in

international collaboration

3

The LUNA collaboration

Italian-German-British-Hungarian collaboration Operates the only underground accelerator of

the world at LNGS, Gran Sasso, Italy Measurement of extremely low cross sections

of astrophysical reactions

4

Reactions studied at LUNA

d(p,)3He

3He(,)7Be

7Be(p,)8B

14N(p,)15O

15N(p,)16O

25Mg(p,)26Al

5

The importance of 3He(,)7Be

4He

2H

3He

7Li

pp-chain of Hydrogen burning,solar neutrinos

big-bang nucleosynthesis,7Li problem

6

Old data of 3He(,)7Be S-factor

0.200

0.300

0.400

0.500

0.600

0.700

0 500 1000 1500 2000Ec.m. [keV]

S f

acto

r [k

eV b

arn

]

Nagatani 1969Parker 1963Krawinkel 1982Robertson 1983Osborn 1984Osborn act. 1984Hilgemeier 1988Nara Singh 2004on-lineactivation

High uncertainty Ambiguous results

pp-chain big bang

7

The LUNA of 3He(,)7Be measurements

Low energies never reached before (Ec.m. = 92 – 170 keV)

With both activation and in-beam methods (good agreement found)

With high precision (<5%)

8

The LUNA results

0.200

0.300

0.400

0.500

0.600

0.700

0 500 1000 1500 2000

Ec.m. [keV]

S f

acto

r [k

eV b

arn

]

Nagatani 1969Parker 1963Krawinkel 1982Robertson 1983Osborn 1984Osborn act. 1984Hilgemeier 1988Nara Singh 2004LUNA activationLUNA on-line

Big bang 7Li problem not solvedby 3He(,)7Be

Solar 8B neutrino flux uncertaintyreduced from ~8% to ~3%

D. Bemmerer et al., Phys. Rev. Lett. 97 (2006) 122502Gy. Gyürky et al., Phys. Rev. C 75 (2007) 035805F. Confortola et al., Phys. Rev. C 75 (2007) 065803

9

ERNA 3He(,)7Be experimentEuropean Recoil Separator for

Nuclear AstrophysicsBochum, Germany (now in Caserta, Italy)

10

ERNA Results

A. di Leva et al., Phys. Rev. Lett. 102 (2009) 232502

11

3He(,)7Be: outlook

new measurements in ATOMKI high energy activation and indirect

measurements (ANC)

12

Experimental study of the astrophysical p-process

n capture

- decay

+ decay

r-pro

cess

p-nucleip-process

13

The p-process nucleosynthesis

Secondary process initiated on s- and r-seeds Several sub-processes involved Most important: -process (-induced

reactions) Models are not able

to reproduce the

observed p-isotope

abundances

14

Data needs for the p-process

Astrophysics: stellar environment temperature density seed abundances time scale etc...

Nuclear physics masses decay properties reaction rates!!!

Reaction rates:• based on theory• very few experimental data• high uncertainty• experiments highly needed

15

Experiments

Alpha-induced reations: 8-15 MeV

Cyclotron

Proton-induced reactions: 1-4 MeV

Van de Graaff

16

Capture reaction cross section measurements

17

10

100

1000

10000

11 12 13 14 15 16 17

Ec.m./MeV

s/m

b

measured data

statistical model calculation

Comparison with theory

130Ba(,)134Ce

Z. Halász et al., in prep.

18

Dependence on input parameters106Cd(,)110Sn

Gy. Gyürky et al., Phys. Rev. C 74 (2006) 025805

19

Fine tuning of parameters

G.G. Kiss et al., Phys. Rev. Lett. 101 (2008) 191101

20

Alpha-nucleus optical potential

E. Somorjai et al., A&A 333 (1998) 1112.

144Sm(,)148Gd

21

Direct determination of alpha-nucleus optical potential High precision elastic scattering experiments Low energies (around Coulomb-barrier) Comparison with global optical potentials Construction of local potentials Experiments:

cyclotron of ATOMKI

22

Capture and scattering experiments

23

Measured complete angular distributions

G.G. Kiss et al., Phys. Rev. C 83 (2011) 065807

s/s R

uth.

24

P-process: Outlook

further needs for experimental data recognized by the scientific community

25

For further information...

http://www.atomki.hu/atomki/IonBeam/nag/index_en.html