Report onNuclear Spectroscopy

at JYFL

Report onNuclear Spectroscopy

at JYFL

• In-beam & Decay Spectroscopy(Daresbury, Liverpool, Manchester, Paisley, Surrey, York)

•Collinear Laser Spectroscopy(Birmingham, Manchester)

•Physics Highlights

The GREAT Focal-Plane Spectrometer for γ-ray, e- -, β -, p- and α- particle detection

• 2 x 60mm x 40mm DSSD (4800 pixels)• 28 x 40mm x 40mm PIN Diodes• 24 x 12 Segmented Planar Ge• Compton-Suppressed Segmented Ge

Clover• Position-Sensitive MWPC

UK Investment

TDR : Total Data Readout

• Triggerless Data Acquisition System

• Rates up to 850 kHz without deadtime

• 380 channels timestampeddata

• 10 ns resolution• Time-of-Day clock with 32

day rollover• Flexible + Easily Scalable

UK Investment

In-beam gamma-ray spectroscopy

JUROGAM ~ EUROGAM 1 (Daresbury)

• 43 EUROGAM Phase 1 Ge detectors + BGO shields

• Eff. at 1.3 MeV 4%

At JYFL:

• 39 EoC pool + 10 UK-France pool Ge detectors

• 30 EoC shields + 15 UK-F shields

•Successor of JUROSPHERE – Eff. 1.5 %

“Complete Spectroscopy”

Jurogam Array

MWPC

PIN DiodesDSSD

Planar

Q1

Q2

Q3

D

RITU gas−filled recoil separator

GREAT

μsApprox 1

Ge (prompt) Recoil Ge (delayed) RecoilΔt Δt

RDT Instrumentation at JYFL

JUROGAMRITUGas-filled recoil separator

Transmission 20-50 %

GREATFocal plane spectrometer

TDRTotal Data ReadoutTriggerless data acquisition systemwith 10 ns time stamping

The Recoil Decay Tagging Technique

Correlate radiation detected at the target position with characteristic decays at the focal plane

JUROGAM+RITU+GREAT experiment at JYFL

J.Simpson, R. Julin et al.,

γ

Energy (keV)

Recoil - γ176Pt

Yrast Band

Energy (keV)

Cou

nts

Cou

nts

α – Recoil - γ

176Hg Yrast BandEnergy (keV)

Cou

nts

Proton Drip Line?

Beta emitter

Z=82

N=82 N=104StableNuclei

Proton emitter Alpha emitter

Au

PbTl

Re

Hg

IrOs

LuHf

WTa

Pt

Yb

The Z ≤ 82 Region

New Isotope

170Pt

163Re159Re

Physics Programme in W-Os-Pt Region

177Hg Melarangi et al., Phys. Rev. C68 (2003) 041301R.

169Os Joss et al., Phys. Rev. C66 (2002) 054311.167,168Os Joss et al., Nucl. Phys. A689 (2001) 631.165,166Os Appelbe et al., Phys. Rev. C66 (2002) 014309.164,166Os King et al., Phys. Rev. C62 (2000) 067301.162Os Joss et al., Phys. Rev. C66 (2002) 014309.

169-173Pt Joss et al., Phys. Rev. C, in press.171Pt Back et al., E. Phys. J A17 (2003) 1.171,172Pt Cederwall et al., Phys. Lett. B443 (1998) 69.168,170Pt King et al., Phys. Lett. B443 (1998) 82.

167Re Joss et al., Phys. Rev. C68 (2003) 014303.

161Re Lagergren et al., submitted to Phys. Rev. C.

159Ta, 160W Keenan et al., Phys. Rev. C63 (2001) 0643309.

In-beam spectroscopy programme

• SHE- nuclei near 254No (Z=102)

•Shape-coexistence in the light Pb region

• Competing structures in W – Pt region approaching the proton drip line

• Isomer – spectroscopy of light (A ≈ 140) Eu – Hf nuclei

• Towards light Z ≈ 50 nuclei

• Studies of light neutron-rich nuclei by deep inelastic collisions (tagging).

•NEW: β – tagging of odd-odd N = Z nuclei

Expt. No Title Spokeperson(s)

JR02 Gamma-ray spectroscopy of the very neutron-deficient nucleus 188Po

P.T. Greenlees S. Juutinen A.N. Andreyev

JR18 Ground state and excited bands in 250Fm R.-D. Herzberg

JR24 A plunger lifetime measurement of low-lying yrast states in 194Po T. Grahn

JR27 Spectroscopy of the deformed ground-state proton emitter 113Cs J.F. Smith

JR29 Spectroscopy of 176Hg: shape coexistence at the extremes

J. Simpson R. Julin

JR30 High-spin states in the N=84 isotones 156Hf, 157Ta and 158W

D.T. Joss J. Uusitalo

JR31 In-beam gamma-spectroscopy study of 253No

R.-D. Herzberg P. Reiter

JR32 Detailed spectroscopy of 191Bi S. Juutinen

JR33 A recoil-decay tagged plunger lifetime measurement for the yrast levels of 186Pb

T. Grahn A. Dewald

JR34 In-beam gamma-ray spectroscopy of the transfermium nucleus 255Lr

P.T. Greenlees R.-D. Herzberg Ch. Theisen

JR35 Identification of excited states in the proton unbound nucleus 166Ir C. Scholey

JUROGAM Campaigns 2003-2006

Expt. No Title Spokeperson(s)

JR01

JR01

Search for triple shape coexistence in 190Po A.N. Andreyev

JR04 A recoil-gated plunger lifetime measurement

of 188Pb with JUROGAM and the RITU separator

A. Dewald

JR05 Recoil-decay tagging employing the alpha-decaying nuclei produced in deep inelastic

reactions J. Uusitalo

JR07 Rotational band structures in the odd-Z transfermium 251Md nucleus studied by

prompt gamma spectroscopy

A. Chatillon P.T. GreenleesR.-D.Herzberg

JR09 The structure of K-isomers at the proton drip-line: 140Dy D.M. Cullen

JR11 Yrast structre of the neutron-deficient nucleus 170Pt D.T. Joss

JR12

JR12

Alpha-decay tagging of 106Te and 107Te B. Cederwall

JR13 Search for spherical, deformed oblate and isomeric states in 184Pb

R. WadsworthR.D. Page R. Julin

JR16 Nuclear structure of the extremely neutron deficient nuclides 161Re and 162Os

K. Lagergren D.T. Joss

JR19 In-beam gamma-spectroscopy study of 254No M. Leino

JR21 Identification of excited states in the first

proton-unbound N=77 isotone 146Tm using recoil-isomer and proton-decay tagging

C. Scholey

JR23 Spectroscopy 223Pa (Z=91): A step towards octupole deformation studies of high-Z nuclei B.J.P.Gall

JR25 Gamma-ray spectroscopy of 192Po with JuroGam P. Rahkila

JR26 Search for an oblate band in 186Pb J. Pakarinen

Expt. No Title Spokeperson(s)

JR10 Proof-of-principle for recoil-beta tagging D. Jenkins

JR15 Gamma-ray spectroscopy of 195At H. Kettunen

JR36

Recoil-decay tagging of exotic light neutron-rich (N<28,Z<18) nuclei employing the alpha-decaying nuclei

produced in deep-inelastic reactions

J. Uusitalo

JR37 Shape co-existence in very neutron-deficient 189Bi S. Juutinen Y. Le Coz

JR39 Identification of excited states in the deformed proton

emitter 117La using recoil-decay tagging with JUROGAM, GREAT and RITU

J.F. Smith

JR40 RDDS lifetime measurements of yrast states in 180,182Hg T. Grahn

JR41 Coulex-plunger lifetime measurements with Xe beams

and test of inverse kinematics for future coulex-plunger experiments

S. Harissopulis

JR42 Search for deformed excitations in 185Pb A.N. Andreyev D.M. Cullen

JR43 Commissioning of the second multi-wire proportional counter for GREAT D.M. Cullen

JR44 Search for N=82 shell quenching for neutron-rich nuclei X. Liang

JR45 In-beam gamma-ray spectroscopy of heavy elements: 256Rf

P.T. Greenlees R.-D. Herzberg Ch.Tiesen B. Gall

JR46 Gamma spectroscopy of 256No using a radioactive 238U target

B. Gall R.-D. Herzberg Ch. Teisen P.T. Greenlees

JR47 Alpha-decay tagging spectroscopy of 110Xe B. Cederwall

JR48 Structure of high-K states in 254No R.-D. Herzberg P.T. Greenlees

JR50 The changing structure of the light Re isotopes: Recoil-decay tagging of the neutron-deficient nucleus 163Re D.T. Joss

JR51 Search for magnetic rotation and superdeformation in 200Po A. Wilson

JR52 Identification of low-lying T=0,1 states in the N=Z nucleus 78Y

S.N.S. Bondili R. Wadsworth

JR53 Investigation of K-isomerism in 250Fm P.T. Greenlees R.-D. Herzberg

JR55 Ground state band of 248Fm R.-D. Herzberg

JR56 Probing the onset of collectively in 196Po by means of RDDS lifetime measurements T. Grahn

JR58 Evolution of single-particle states near the N=82 shell gap; spectroscopy of 168Pt and neighbouring isotopes M. Boden Gomez

JR59 Recoil-Decay Tagging spectroscopy of 172-176Au B. Cederwall

JR60 Decay studies of the isomers in the proton emitter 151Lu and its daughter nucleus 150Yb Z. Liu

Campaign 1 4/2003 – 12/2003 : 9 months 14 experiments

Campaign 2 4/2004-6/2004 10/2004-3/2005 : 9 months 13+1 experiments

Campaign 3 9/2005 – 9/2006 : 12 months 13 experiments

Spectroscopy of very neutron deficient Spectroscopy of very neutron deficient and heavy nuclei and heavy nuclei

+ + Can be produced via fusion evaporation with stableCan be produced via fusion evaporation with stable--ionion beams and stablebeams and stable targetstargets++ ShortShort--livingliving alpha or proton emitters alpha or proton emitters →→ taggingtagging methodsmethods-- CrossCross--sectionssections down to 1 nbdown to 1 nb-- OnlyOnly levelslevels near the yrast line populatednear the yrast line populated

Superheavy NucleiProduced in asymmetric cold-fusion reaction – X(48Ca,2n)Y→ ideal for 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

Odd Z251Md, 255Lr

Odd N253No

Even Z252No254No250Fm248Fm

Future:256Rf

Darmstadtium

S. Hofmann, Nucl. Phys. News Intl

108110

112114

120Shell-CorrectionEnergies

-7 MeV-6 MeV-5 MeV-4 MeV-3 MeV

R. Smolanczuk et al.,Phys. Rev. C 52, 1872(1995)

R. Smolanczuk and A. Sobiczewski,Proc. XV Nucl. Phys. Div. Conf., Singapore (1995), p. 313

Motivation

What determines stability?

sea of instability

Magic Numbers

Neutrons Protons

20, 50, 20, 50

82, 126 82, ???

island of spherical

SHE

peak of Sn

peak of Ca

peak of Pb

peak of Th,U

strait of radioactivity

Number of neutrons

Nu

mbe

r of

pro

ton

s

20

50

82

114

20 82 126 184

In-beam Data

Single Particle States

Neu

trons

Pro

tons

9/2+[624]

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 data254254NoNo

SAGE : 2007

Simultaneous Gamma & Conversion electron studies

Triple Triple -- shape coexistenceshape coexistenceIn Pb isotopesIn Pb isotopes

Close to the proton dripClose to the proton drip--lineline

Shape coexistence near the Z=82 shell closure

A phenomenon where nuclear configurations at similar excitation energies are built on very different

deformations.

Shape coexistence is expected to occur in transitional regions between weakly and strongly

deformed ground states

E (ħ

ω)

ε2

GROUND STATE

(Weakly Deformed)

INTRUDER

(Well Deformed)

PROLATEOBLATESPHERICAL

A. Andreyev et al. Nature 405 (2000) 430

0p-0h 2p-2h 4p-4h

Three lowThree low--lying 0lying 0++ states in states in 186186Pb observed in the Pb observed in the αα-- decay of decay of 190190PoPo

Where is theOBLATE band?

Even-mass Pb isotopeslevel systematics

Oblate

2p-2

h

Prolate 4p-4h

Spherical 0p-0h

PbPb

186 P

b

RDT experiment for 186Pb with JUROGAM+RITU+GREAT106Pd(83Kr,3n) 186Pb

A NEW BAND

THE PROLATE BAND

186Pb

186Pb

OBLATEOCTUPOLE

PROLATE

GAMMA

186P

b OBLAT

E

Pb PROLATE

Kinematic moment of inertia

Po OBLATE

188P

b OBL

ATE

DifferentialDifferential--PlungerPlunger--Lifetime measurements by using RDT Lifetime measurements by using RDT for intruder bands in very neutron deficient for intruder bands in very neutron deficient 186,188186,188Pb and Pb and 194194PoPo

114Cd(83Kr,3n)194Po

Differential plunger inside JUROGAM

194Po188 Pb

186PbProlate 4p-4h

Oblate 4p-4h

Proton Emitting Nuclei

156Tagm

159Re 160Re 161Regm

155Ta

162Rem g

163Rem g

157Tam1 gm2

158Tam1 gm2

159Tam g

160Tam g

164Ir 165Ir 166Irm g

167Irm g77

Z = 75

73

α decay

proton decay

β decaym isomeric stateg ground state

RDT of the proton emitter 161ReSpectroscopy of Proton Emitters

bα = 92 %bp = 8 %

bp = 100 %

K. Lagergren et al., Submitted to Physical Review C.

Experimental details

Planar Ge

Clover Ge

58Ni + 106Cd → 164Os*

@ 300MeV159Re, p4n160Re, p3n

106Cd 1.1mg/cm2 &

Avg IB ~ 7 pnA

Searching for proton emitters

Counts (105) per 2keV

E (keV)2000

40006000

8000

0 2 4 6 8

152Er

153Tm

156mLu

156mHfEscaped α particles

E (keV)

Counts per 2keV

2000 4000 6000 8000

0

2

4

6

8

162Os

159Re

Δt (μs)

Co

un

ts

0 50 100 150 200

0

2

4

Re

prot

on

emis

sion

159 R

e

158 W

162 O

s

E p=

1805

keVT 1

/2=

21μs

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Joss

, RD

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Dar

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Sim

pson

et a

l.,

Re

Isom

eric

πh 1

1/2

stat

e

159Re proton decay Q value (MeV)

Partial half life (secs)

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

10–9

10–8

10–7

10–6

10–5

10–4

10–3

10–2

10–1

100

101

102

103

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s 1/2

d 3/2

h 11/

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