Laser spectroscopy of gallium isotopes using...
Transcript of Laser spectroscopy of gallium isotopes using...
Laser spectroscopy of gallium isotopes using ISCOOL
Optical measurementsin the region
N=50
Z=2829Cu31Ga
N=40
➔ spins, μ, Qs, δ< r 2 >
Physics motivation
Use laser spectroscopy to measure the gs spins...
Tensor force attractive between L+1/2 and L-1/2 (esp with ~radial wavefn)
28 28
40 401g9/2 1g9/2
2p1/21f5/2
1p3/2
1f7/2
2p1/21f5/2
2p3/2
1f7/2
Otsuka (PRL 95 232502):-
Does 5/2 replace 3/2 as gs in Ga? When?
Laser spectroscopy at CollapsProtons
Magnets
ISCOOL
0 cm-1826 cm-1
34782 cm-1
288 nm 295 nm
532 nm
RILISp-n converter
200ms PMT
ISCOOL for cooling & bunching
Photon background dominated by continuous
laser scatter
6μs gate
Example spectrum - 76Ga
Ungated
Gated (64μs - 70μs)
Time of flight(50ms accumulation)
Background suppression50ms / 6μs = ~104
417nm Ga I spectra826 cm-1 3d104s24p 2P3/2 ➔ 24789 cm-1 4s25s 2S1/2
3/2
3/2
3/23/2
3/2
(3/2)(3/2)
(5/2)
1
1
3(3)
2,3)
(3)(3)
1,2,3)
The strange case of 73Ga
All odd-A states previouslyassigned I=3/2
Au/Al ≠ 5.59(2)
π(p3/2)3 - hole state
403nm (2P1/2 ➔ 2S1/2) transition
F=1F=0J=1/2
F=1F=0J=1/2
F=2F=1J=1/2
F=2F=1J=1/2
I=3/2 I=1/2
➔ Must be spin 1/2
Intensity distribution (403nm)✔ Number of peaks
✔ Intensity distribution
✔ Au(2S1/2):Al(2P3/2) ratio
Gallium level systematicsNo low-lying
spin-1/2 state observed in 73Ga
Dip in 9/2 energyat this point
(onset of deformation)I. Stefanescu et al. PRC 79, 064302 (2009)
Shell model predictions
N. Yoshinaga,K. Higashiyama,and P. H. ReganPRC 78 044320 (2008)
Pairing + QQusing a valence space made up from nucleons occupying the g9/2, p1/2, p3/2 and f5/2 orbitals
Searching for the I=5/2...
75,77,79Ga are I = 3/281Ga is I = 5/2
Four 81Ga spectra:-
Odd-odd Ga isotopesIsomeric statediscovered in 80Ga
I=3
Can assign as I=2
No detectable splitting
Agrees with ABMR
Gallium nuclear moments
N=40 N=50 N=40 N=50
g-factors Qs
76 78
• g-factors of 75,77Ga similar to 67,69,71Ga➔ but different structure (Q < 0)
• Staggering of quadrupole moments 75,76,77,78Ga
Comparison with theory (Energy)JU
N45
inte
ract
ion
3/2 3/2 3/2 3/2 5/2 5/2
106
390
487
1107
199
<1
651
22
229
606
1895
279 351
5/21/2
7/2
5/2
7/2
1/25/2
1/2 5/21/2
3/2
1/2
7/2
7/2
1/2
3/2388
478
1168
61219
798
76181
152
251 350
430
1124
450
1263
1800
7/21593
5/2
3/2
1/2
1249
1111
882 5/21/2
3/2
7/21210
878
368
846
5/2
1/27/2
7/2
3/2339
653
768
10791082 1/2
7/2
7/2
5/2
3/2407
634
868
10751201 7/2
1/2
3/2
5/2
138
987
12101256
3/21024
5/21727
jj44b
inte
ract
ion
3/2 3/2 3/2 3/2 3/2 5/2
1/2
7/2
5/2336
412
822
1/25/2
7/2
1/25/2
7/2
5/21/2
7/2
3/2
1/27/2
5/2
1/2
7/2
91251
844
81244
803
216282
953
38
504
1026
239
12801458
Expe
rimen
t
71Ga 73Ga 75Ga 77Ga 79Ga 81Ga3/2 1/2 3/2 3/2 3/2 5/2
1/25/2
7/2
(7/2)
5/2 (5/2)(1/2)
(7/2)
(5/2)(1/2)
(7/2)
(5/2)
3/2
3/2
JUN45 - M. Honma
jj44b - B.A. BrownSpin inversion ✔
Low I=1/2 state in 73Ga ✔
Experimental1/2-, 3/2-, 5/2-, 7/2-
Theory - nuclear momentsMagnetic dipole Electric quadrupole
Fails for 79Ga in particular ....
Theory - nuclear momentsMagnetic dipole Electric quadrupole
“Second” 3/2 states..or the gs?
Isotope shift data
Need to calculate atomic factors...
Summary and outlook• Inversion seen between 79Ga and 81Ga• 73Ga is I = 1/2 (not I = 3/2)• Spins also confirmed for 76,77,78,79,80,81Ga
• Isomeric state discovered in 80Ga
• Theoretical predictions of moments
• Analysis of charge radii data
See talk by Pieter Vingerhoets (Cu) isotopes
Collaborating institutions
Manchester, UKKU Leuven, BelgiumBirmingham, UKISOLDE, CERNJyväskylä, FinlandOrsay, FranceHeidelberg, GermanyMainz, GermanyNew York, USA
Beta_2 values
67 +0.1669 +0.1371 +0.0875 -0.2576 +0.1777 -0.1878 +0.1779 +0.1281 -0.02