Along the N=126 closed shell: study of 205 Au through its πh 11/2 -1 isomeric decay Zs.Podolyák, A.Algora, C.Brandau, K.Burkard, P. Butler, J.Cederkall,

Along the N=126 closed shell: study of 205Au through its πh11/2

-1 isomeric decay

Zs.Podolyák, A.Algora, C.Brandau, K.Burkard, P. Butler, J.Cederkall, V.N.Fedosseev, L.M.Fraile, A.Garnsworthy, W.Gelletly, G.Jones, Z.Liu, P.H.Regan, B.Rubio, Ch.Scheidenberger, S.Steer, T.Storra, N.Thompson, P.M.Walker, S.Williams

University of Surrey, Guildford, UK ISOLDE, CERN, Switzerland IFIC, CSIC-University of Valencia, Spain ATOMKI, Debrecen, Hungary GSI, Darmstadt, Germany

Beta decay of 130Cd

I.Dillmann et al., Phys. Rev. Lett. 91 (2003) 162503

Qβ in agreement with mass theories considering shell quenching at N=82

Evolution of shell structure: -disappearance of magic numbers (new ones appear) –light nuclei

-shell quenching

Suggested shell quenching at N=82

What about the N=126 shell closure?

Excited states of N=126 nuclei ‘below’ 208Pb

prel

imin

ary

N=

126,

4 p

roto

n ho

les

N=

126,

4 p

roto

n ho

les

GSI, FRS, March 2006

Sensitive to lifetimes < 1 ms

S.Steer, Zs.Podolyák et al.

(197Au: B(M4)=2.4(8) W.u. 207Tl: B(M4) =3.2(3) W.u.)

201Au T1/2 ~21s203Au ~13s205Au (Ex=700 keV) ~6.3s (Ex=1000 keV) ~0.33s

?

Experimental aims:energy of the πh11/2

-1 proton-hole orbitalπh11/2

-1 -> πd3/2-1 transition strength

(maybe πh11/2-1 -> πs1/2

-1 transition strength)

B(E4)=3.1(21) W.u.

B(E4)=3.2(13) W.u.

N=120Future: Ir nuclei?

ISOLDE could do it!

Experiment

-ionisation scheme already developed (RILIS efficiency 3%) high beam intensity- tape system (isobaric conaminants and Au groundstate live longer)- gamma (Ge) + beta+ conversion electron (mini-orange) measurement (effic. ~2% ~30% ~5%)

beam

Ge (above)

Ge

Si(Li)

scintillator (β)

mini-orange

beam Max. available intensity

target Ion source shifts

201Au 1x106 ion/s UCx RILIS 3

203Au 5x105 ion/s UCx RILIS 3

205Au 2x105 ion/s UCx RILIS 3

Beam request

Much less is enough