saclay, 30 january 2007 rauno julin department of physics university of jyväskylä finland jyfl

Saclay, 30 January 2007Saclay, 30 January 2007Rauno JulinRauno Julin

Department of PhysicsDepartment of PhysicsUniversity of JyväskyläUniversity of Jyväskylä

FinlandFinlandJYFLJYFL

In-beam In-beam Spectroscopy of Spectroscopy of Transfermium NucleiTransfermium Nuclei

Outline:

Introduction

Even-Even254No ( Z =102, N = 152 )250Fm ( Z =100, N = 150 )

Odd-Proton251Md (Z = 101, N = 150)255Lr (Z = 103, N = 152)

Odd-Neutron 253No (Z = 102, N = 151)

Future plans

Spectroscopy of very neutron deficient Spectroscopy of very neutron deficient and heavy nuclei at JYFLand heavy nuclei at JYFL

Can be produced via fusion evaporation with stable-ion beams and stable targets Can be produced via fusion evaporation with stable-ion beams and stable targets

Short-living alpha or proton emitters → tagging methodsShort-living alpha or proton emitters → tagging methods Cross-sections down to 1 nbCross-sections down to 1 nb

Only levels near the yrast line populatedOnly levels near the yrast line populated

Recoil – Decay –Tagging (RDT) method

JUROGAM 43 Ge + BGO Eff. 4%

RITUGas-filled recoil

separator

Transmission 20-50 %

GREATFocal plane spectrometer

TDRTotal Data ReadoutTriggerless data acquisition systemwith 10 ns time stamping+ GRAIN the Analyser

RDT Instrumentation at JYFL

prompt e -

SACRED electron spectrometer at the RITU target

Transfermium NucleiProduced in asymmetric cold-fusion reaction – X(48Ca,2n)Y → ideal for the gas-filled separator RITU→ Only one reaction channel open→ Total compound cross-section down to 50 mb → Ibeam up to 30pnA on a 0.5mg/cm2 target in in-beam runsFission dominates: 100000 : 1→ Ibeam limited by the Ge rate→ Very low focal-plane rate→ Enables long t1/2 – α – tagging

254NoZ = 102, N = 152

254254NoNo

842

943

In-beam γ- rays from 208Pb(48Ca,2n) 254No - 2µbJUROGAM + RITU

S. Eeckhaudt et al. EPJ A26, (2005), 227

0

250

500

750

1000

12501500

1750

2000

2250

2500

2750

3000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

I [hbar]

Ele

vel

[keV

]

In-beam γγ coincidences from 254No 254254NoNo

?

254No-recoil gated in-beam conversion electrons from

208Pb(48Ca,2n) 254No

Discrete lines

+

M1 continuum

M1

P.A. Butler at al. PRL 89 (2002) 202501

SACRED + RITU data

254254NoNo

254No Levelscheme

Long isomer

Short isomer

3+

8-

(16+)

55 s

R.-D. Herzberg et al. Nature 442, 896-899 (24 August 2006)

250FmZ = 100, N = 150

Singles Gamma-Ray Spectra from 204Hg(48Ca,2n)250Fm(HgS targets)

A. Pritchard, R.-D. Herzberg et al., University of Liverpool

250Fm electron spectra

250Fm preliminaryPT G

reen

lees, R

DH

et a

l, pre

limin

ary

!

JUROGAMTagged with isomer

250Fm LevelschemePT G

reen

lees, R

DH

et a

l, pre

limin

ary

!

?

?

Kinematic moment of inertia J(1) even – even nuclei

Dynamic moment of inertia J(2)

even – even nuclei

0,05 0,10 0,15 0,20 0,25

60

70

80

90

100

110

120

130

140

254No

252No

250Fm

I(2) [h

2 /MeV

]

Rotational frequency [MeV]

Dynamic moment of inertia

even – even nuclei

250Fm Dynamic Moment of Inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

♦ Exp

A Afanasiev, priv comm.

250Fm Kinematic and Dynamic Moment of Inertia J(1) and J(2)

A. Afanasiev, PRC 67, 24309, (2002)

Kinematic and Dynamic Moments of Inertia J(1) and J(2)

Odd - proton 251Md150 , 255Lr152

[521]1/2-

[514]7/2-

[633]7/2+

Electromagnetic Properties

• Odd-proton orbitals in 251Md / 255Lr• B(M1)/B(E2) depends on (gK-gR)/Q0

gK ~ 0.7 Mainly E2[514] 7-

2

7 -

2

7 +

2

[633] 7+

2gK ~ 1.3 Mainly M1

1 -

2

[521] 1-

2a ~ 0.9:

gK ~ -0.55

Mainly E2

Conversion coefficients Z ≈102

Prompt γ-ray spectroscopy of 251Md and 255Lr

205Tl(48Ca,2n)251Md ~ 760 nb(A. Chatillon, Ch. Theisen et al. )

209Bi(48Ca,2n)255Lr~ 300 nb(S. Ketelhut, P. Greenlees et al.)

Recoil Tagging

γγ coincidences

First rotational band in an odd-Z transfermium

No signature partner : K=1/2 251Md

Dynamical Moments of Inertia J(2)

J (2

) (h

bar

2 MeV

-1)

Rotational Frequency

251Md Dynamic Moment of Inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

185

200

HFB + SLy4M. Bender et al.

300

430

W.S.S. Ćwiok et al.

½-

7+

2

HFB + GognyH. Goutte, priv. comm.

100

7-2

½- ½-

7-2

7-2

7+

2

7+

2

255Lr – Recoil Tagging209Bi(48Ca,2n)255Lr

255Lr – Recoil Decay Tagging

Comparison 255Lr – 251Md

Odd - neutron 253No151

Confirmed byF.P. Heßberger et al.E.P.J. A 22, 417 (2004)

The ground state of 253No is a neutron 9/2- [734] state

0

25

50

75

100

125

Co

unts

/ke

V

100 200 300 400Ene rg y [ke V]

0

2

4

6

8

10

Co

unts

/5 k

eV

GREAT spectra from 207Pb(48Ca,2n)253No

γ rays

electrons

253253NoNo

1.7 min

EarlierGammasphere+FMA

experiment207Pb(48Ca,2n)253No – 0.5µb

P. Reiter et al. PRL 95, 032501 (2005)

253253 NoNo

253253 NoNo JUROGAM + RITU

Recoil-gated γ rays from 207Pb(48Ca,2n)253No

253

253 NoNo Exp

K=7/2 simulation

K=9/2 simulation

It is not 7/2+[624] band but 9/2-[734]

253No

It is not 7/2+[624] band but 9/2-[734]

253No

253253 NoNo

SACRED + RITU data

In-beam conversion electrons from 207Pb(48Ca,2n) 253No

K=7/2 simulation

K=9/2 simulation

Exp

9/2- [734]Indeed

P. Butler et al.

Dynamic moment of inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

PERSPECTIVES

Improved sensitivity for in-beam studies:Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting Digital signal processing → Higher counting

raterate

Development of high-intensity beams

In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron spectrometer -

SAGE

PERSPECTIVES

Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting rate

Development of high-intensity beamsDevelopment of high-intensity beams• 5050Ti + Ti + 208208Pb → Pb → 256256Rf + 2n Rf + 2n

In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron spectrometer -

SAGE

In-beam γ rays from 208Pb(50Ti,2n)256Rf – 12nb700 recoils ↔ 25pnA, 1 week

Simulation – a random bit of the 254No experiment

256RfZ = 104

PERSPECTIVES

Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting rate

Development of high-intensity beams

In-beam gamma - electron concidences for SHE: In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron Combined gamma-ray and electron

spectrometer - SAGEspectrometer - SAGE

SAGESAGEUK investment

SAGESAGE

Collaborating institutes

Thank you for your attention !Thank you for your attention !

Moment of inertia