Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL
57
Saclay, 30 January Saclay, 30 January 2007 2007 Rauno Julin Rauno Julin Department of Physics Department of Physics University of University of Jyväskylä Jyväskylä Finland Finland JYFL JYFL In-beam In-beam Spectroscopy of Spectroscopy of Transfermium Nuclei Transfermium Nuclei
description
In-beam Spectroscopy of Transfermium Nuclei. Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL. Outline: Introduction Even-Even 254 No ( Z =102, N = 152 ) 250 Fm ( Z =100, N = 150 ) Odd-Proton 251 Md (Z = 101, N = 150) - PowerPoint PPT Presentation
Transcript of 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
