Andreas Heusler

Heidelberg

Identification of the

Proton Pairing Vibration State

in Pb at E = 5667 keV208

x

HK 16.8 DPG Frühjahrstagung Heidelberg 2015

Pairing vibration 0 states in Pb+ 208

The four lowest 0 states in Pb+ 208

Three 0 states in Pb are known

The proton pairing vibration state is unknown

+ 208

Pb(t,p), Pb(p,t) Igo et al Phys Rev Lett 24:470(1970)

Pb(n,n' γ) Yeh et al Phys Rev Lett 76:1208(1996)

206 210

208

xE = 0 keV

E = 4868 keV

E = 5241 keV

x

x

D1 Q D2 D3

14 MV tandem accelerator

Maier-Leibnitz-Laboratorium of LMU & TU München

proton

Q3D magnetic spectrograph

proton E =14-18 MeV

detector

target

Θ=20°-140°

p

detector

detector

Spectra of Pb(α,α'), Pb(p,p') and Pb(d,p)

Valnion et alZ Phys A350:11(1994)

?

The reaction (α,α') excites only natural parity states.Below 6 MeV, all states with negative parity

and most states with positive parity are known.

208 207

208

5667 state observed by Pb(a,a') Valnion et alZ Phys A350:11(1994)

natural parity

!?!

208cts

60

40

20

0~200 cts

Spectra of Pb(p,p') and 208Pb(d,d')c

o

u

n

t

s

satellite from knockout of L-electron with E =15 keV

E(proton) 14.9 MeV

15.7 MeV

16.5 MeV

208

~3000 cts

~3000 cts

bind

on g IAR

on i IAR

near d IAR

9/2

11/2

5/2

5667 0

5241 0

4868 0

+3

+1

+2

- 0.21 MeV - 0.21 MeV

0.80

0.55

0.65

+1, 2, 3

Coulomb displacement energyCurutchet et al PLB 208:331 (1988)

Calculation of mixing among 0 states

surface

proton pairing

neutron pairing

vibration

Excitation functions and angular distributions of Pb(p,p')

ν g9/2 f7/2 + ν d5/2 f5/2

π h9/2 d5/2 + ν d5/2 f5/2

proton pairing vibration

E(proton) = 14.9 15.7 16.4 16.5 16.9 17.5 MeV

208

The 0 proton pairing vibration state in Pb is identified208

x

x

x

x

E = 0 keV

E = 4868 keV

E = 5241 keV

E = 5667 keV

208

x

x

x

x

+