Studies of the shapes of heavy
pear-shaped nuclei at ISOLDE
Peter Butler
University of Liverpool
Rotating even-even nuclei
E3 moments 220Rn, 224RaPeter Butler

Odd-mass nuclei & EDMs
Spectroscopy with TSRRotating octupole shapes

3ħ3ħ
0ħ
0ħ
Octupole vibrationalPeter Butler

Octupole deformed

Actual Behaviour (near the ground state)3ħ

Octupole vibrational

0ħ

3ħ

0ħ
Octupole deformed3ħ

0ħ

JFC Cocks et al PRL 78 (1997) 2920, Nucl. Phys. A645 (1999) 61
Peter Butler

B(E3) transitions

Q3 37ZeR03  3 3  f (  3 ,...)
7B ( E 3; I i  I f )  I i 030 | I f 0  2 Q3216

B(E3; 0+ → 3-) ~ 30 – 50 single particle units for b3 ~ 0.1
B(E1) ~ 10-(2-3) single particle units
B(E2) ~ 100 single particle units
Peter Butler

Recent experimental results (REX-ISOLDE)
3.105 /s 220Rn
2.8 MeV.A

7.105 /s 224Ra
2.8 MeV.A

60Ni target
120Sn target

220Rn

Peter Butler

224Ra

LP Gaffney et al
Nature 497 (2013) 199

E2 and E3 moments in “octupole” mass region

octupolevibrationalPeter Butlerradioactivebeams

radioactivetargets(2013)(1993)

Rotating charged pear-shape
220Rn

224Ra

226Ra
HJ Wollersheim et al.,NP A556 (1993) 261
Peter Butler<4+||E3||1->E2 matrix elements [e·fm2]

E3 matrix elements [e·fm3]

Comparison with theory

12
2
3
4
5

Peter Butler

1. Shneidman et al PRC 67 (2003) 014313
2. Robledo & Butler PRC 88 (2013) 051302(R)
3. Rutz et al. NP A590 (1995) 680
4. Engel et al. PRC 68 (2003) 025501
5. Nazarewicz et al NP A429 (1984) 269

Neutron and Atomic EDM momentStatic Electric Dipole Moment implies CP-violation[Pendlebury & Hinds
NIM A440 (2000) 471]

Schiff Theorem: neutral atomic system of point particles inelectric field readjusts itself to give zero E field at all charges.
BUT: finite size and shape of nucleus breaks the symmetryPeter Butler

Octupole enhanced atomic EDM moment
EDM programme atGroningen, ANL (225Ra) PS1-071
and TRIUMF (223Rn)

related to Q3

PR C 56 (1997) 1357

energy splitting of parity doublet in odd-A nuclei

P,T-violating n-n interaction

J  Sˆ z  VˆPT 
Schiff moment: S  2
EV Spevak, N Auerbach, and VV Flambaum J  1

Measured in 223,225Ra(but not odd-A Rn)

J Dobaczewski and J EngelPRL 94 (2005) 232502
J Ellis, JS Lee and A Pilaftsis
JHEP 02 (2011) 045

Measured in 220Rn,224,226Ra(but not odd-A nuclei)

Nuclear spectroscopy programme
Kα

221Rn, 6x103 ion/s

30 hour beam time120Sn target, 2 mg/cm2KβPeter Butler

201 224

273287

George O’Neill

Future at HIE-ISOLDE (1) :221,222,224,226Rn, 222, 228Ra
MINIBALL + SPEDE
PS1-057

Future at HIE-ISOLDE (2) : Storage Ring TSR
PS1-126

electroncooler

HELIOS

ExtractionPeter Butler

In-ringexperiment

Injection
HIE-ISOLDE

11Helical Orbit Spectrometer
AH Wuosmaa et al
NIM A580 (2007) 1290

B

Eliminates:
kinematic broadening
Q-value compression

10 MeV/u d(132Sn,p)133Sn*
Q-value = 1.01 Elab - 9.92 - 0.21 z

4 MeV/u 12C(224Ra,12C’)224Ra*
Q-value = 1.05 Elab - 0.80 z

10 MeV/u d(223Ra,d’)223Ra*
Q-value = 1.01 Elab - 0.17 z
Peter Butler

Contributions to Q-value resolution
B field
detectorX,Z

Direct beam from HIE-ISOLDE

detector DE

beam diverge

DEFWHM (total) ~ 40 keV
for (d,d’) or (d,p)

DE beam target
beam spot

DE ejectile target

ejectile scatterbeam scatterbeam DEbeam straggle

ejectile straggle
B field

beam spot

beamdiverge

detector X,Zbeam DEejectile straggle
detector DE

beam straggle
ejectile scatterDE beamtarget

Peter Butler

Cooled beam from TSR
DEFWHM (total) ~ 20 keV

DE ejectile
targetbeam scatter

Measuring B(E3)s in 225Ra parity doublet
226Ra(d,d’)actual data

DE ~ 10 keVThorsteinsen et al.
Phys. Scr. 42 (1990) 141-400-200

225Ra(d,d’)2022 ?

l =2 l =2+3/2+ 5/2

l =4 l =3
7/2+1/2+ 9/2+ 7/2 l=1 l=1
1/2- 3/2-

DE ~ 20 keVPeter Butler

Q-value (keV)0
1/2+Summary
Strong circumstantial evidence that some nuclei are pearshaped. Evidence comes from behaviour of energy levels
and B(E3)s.
Odd mass octupole-deformed nuclei offer greatly increased
sensitivity for EDM searches.

Measurement of B(E3) in odd-A nuclei will benefit frombeam cooling.
CERN-ISOLDE (T STORA, F WENANDER)
Technische Universität Darmstadt
University of Edinburgh
GANIL
University of Jyväskylä
Universität zu Köln
KU Leuven
Lawrence Livermore National Lab
Peter Butler University of Liverpool (L GAFFNEY)

University of Lund
Universidad Autónoma de Madrid
University of Michigan
Ludwig-Maximilians-Universität andTechnische Universität München
SCK CEN
University of Rochester
University of Warsaw, Heavy Ion Lab
University of York