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