AGATA@GSI LoI

Relativistic Coulomb M1 excitation of neutron-rich

85BrN. PietrallaG. Rainovski

J. Gerl

D. Jenkins

Evolution of the proton SPEs towards 78NiApproaching 78Ni from left - N=40 to N=50

Z=28

50

K.T. Flanagan et al., PRL 103, 142501 (2009) T. Otsuka et al., PRL 104, 012501 (2010)

89Y, NNDC; 87Rb, L. Käubler et al., PRC 65, 054315; 85Br NNDC; 83As, NNDC and E, Sahin et al., AIP Conf. Proc. 1072, 298 (2008), 1012, 139 (2008); 81Ga, D. Verney at al. PRC 76, 054312 (2007)

39

?

(391)

(0)

p 1/2

p 1/2

p 3/2p 3/2

p 3/2

f5/2 f5/2 f5/2

p 1/2

p 3/2

f5/2 - 345

1191

0 0

306

669

0

351

p 1/2

p 3/2

f5/2

845

- 403

0p 1/2

p 3/2

f5/2

0

- 1507

- 1745

ESPE

(kEV

)

39 37 35 33 31 29

Approaching 78Ni from above - Z=40 to Z=28

1/2-

3/2-5/2-

15071745

0

15071745

89Y

1/2-

3/2-

5/2-

845

403

0403

845

87Rb

(1/2)-

(5/2,3/2)- -

(3/2,5/2)- -

0

306

669

306

363

83As

(5/2)-

(3/2)-

(3/2)-

0

351

803

351

452

81Ga

1/2-

3/2-

5/2- 345

1191

0345

1191

85Br 79Cu

?(1/2)-

(3/2)-

(5/2)-

(391)

(0)

?

1) E(p3/2) – E(f5/2) constant

2) E(p1/2) – evolves ???28

50

p1/2 ???

What is the unique experimental signature of p1/2?

1/2-

3/2-5/2-

15071745

0

15071745

89Y

1/2-

3/2-

5/2-

845

403

0403

845

87Rb

1/2-

3/2-

5/2- 345

1191

0345

1191

85Br

Spin-flip M1 transitions: direct observation of spin-orbit splitting

Relativistic Coulomb excitation reactions

1p (l=1)

j < =

l-1/

21p1/2

j> = l+1/2

1p3/2

B(M1;j>j<) 1 N2

Unique signature!!!

0.68(10) N2

0.47(5) N2

???

c(E2) (1/)2

c(M1) – independent

at high v/c large M1 matrix elements can significantly contribute to the total CE yieldRelativistic beam energies

50-80 %

Huge Doppler spread in the

observed -ray spectrum

need of capability to perform precise Doppler

correction and reduce the Doppler broadening

AGATA

Unique at GSI

Test case – 85Br

1/2-

3/2-

5/2- 345

1191

0345

1191

• primary beam – 86Kr with intensity of about 109 pps • primary target – 2 g/cm2 9Be

• secondary beam – 85Br, produced in fragmentation - 10 mb • secondary beam energies – 200 MeV/u and 450 MeV/u• beam intensity at S4 – 105 pps (10% FRS efficiency)• yield estimates - 10% efficiency of AGATA+PRESPEC set-up

Assume the same strengths as in 87Kr:B(E2;5/2-3/2-)= 40 e2fm4 B(M1;5/2-3/2-)=10-2N

2

B(M1;1/2-3/2-)=0.58 N2

Ebeam(MeV/u) v/c Elevel(keV) J CE(mb) Yield (/h)

200 0.57345 5/2- 6.94 234

1191 1/2- 0.64 22

450 0.74345 5/2- 4.21 142

1191 1/2- 0.78 26

• Disentangle E2 and population from GDR: DSAM, two beam energies and multiplicity-total energy gates HECTOR

Beam time – 100 h85Br

SummaryRelativistic Coulomb M1 excitation of neutron-rich 85Br

• physics goal - to fix the relative spacing between the p1/2 and p3/2 orbitals in the neutron rich nucleus 85Br• methodological goal - to show that the method of relativistic Coulomb excitation is a reliable experimental tool for quantitative study of M1 excitation strengths in exotic nuclei

Requires RIB at relativistic energies –

unique at GSIRequires capability for high resolution -ray spectrometry at

v/c 50-80% - needs AGATA