Odd-odd N=ZOdd-odd N=Z
Fascinating laboratory for Fascinating laboratory for studying interplay of T=0 and studying interplay of T=0 and T=1 statesT=1 states
Very unusual low level Very unusual low level density for odd-odd nuclei density for odd-odd nuclei e.g. only 1 state below 1 MeV e.g. only 1 state below 1 MeV in in 7070BrBr
Evidence for np-pairing in Evidence for np-pairing in both low lying states and high both low lying states and high spin rotational bandsspin rotational bands
Beta decays important for Beta decays important for standard model tests - CVC standard model tests - CVC hypothesishypothesis
How to study odd-odd N=ZHow to study odd-odd N=Z
Nuclei are difficult to produce without reactions close to 40Ca+40Ca at near-barrier energies
Production cross-sections are low (<1% of total cross-section) Residues are too slow at focal plane of separator e.g. FMA to use ion
chamber to identify Z Most measurements done with neutron detectors + charge particle
detectors to select e.g. pn or pn channel
Nuclei are difficult to produce without reactions close to 40Ca+40Ca at near-barrier energies
Production cross-sections are low (<1% of total cross-section) Residues are too slow at focal plane of separator e.g. FMA to use ion
chamber to identify Z Most measurements done with neutron detectors + charge particle
detectors to select e.g. pn or pn channel
Proof-of-principleProof-of-principle
natCa (36Ar, pn) 74Rb Ebeam = 103 MeV τ½ (74Rb) = 65 ms β+
endpoint ~ 10 MeV σ ~ 10 μb
natCa (36Ar, pn) 74Rb Ebeam = 103 MeV τ½ (74Rb) = 65 ms β+
endpoint ~ 10 MeV σ ~ 10 μb
Unknown case:78YUnknown case:78Y
Nothing known about 78Y except 0+ superallowed decay and (5+) beta-decaying isomer
RBT technique applied using 40Ca(40Ca,pn)78Y reaction
Cross-section should be very similar to 74Rb
90% of flux proceeds to low-lying isomer
Isomer is too long-lived for effective tagging
Nothing known about 78Y except 0+ superallowed decay and (5+) beta-decaying isomer
RBT technique applied using 40Ca(40Ca,pn)78Y reaction
Cross-section should be very similar to 74Rb
90% of flux proceeds to low-lying isomer
Isomer is too long-lived for effective tagging
Coulomb Energy Differences
Extremely sensitive to nuclear structure effects:
•Rotational alignment mechanism •Correlations of pairs of particles •Changes in deformation•The evolution of nuclear radii D.D. Warner et al., Nature Physics 2, 311 (2006)
CEDs for A~70
Difference in np and NN pairs gives CED rise of ~12 keV/J
Uniform upward trend for deformed nuclei except:
A=78 - flat
A=70 - strongly down
A=70 data from G. de Angelis, EPJ A12, 51 (2001) and
D.G. Jenkins et al., PRC 65, 064307 (2002)
CED(J)=Ex(J,T=1,Tz<)-Ex(J,T=1,Tz>)
Effect of shape changeEffect of shape change
2=-0.3 2=0.35
2=0.18 2=0.35
CED=-7 keV
CED=-75 keV
R. Sahu et al., J. Phys. G 13, 603 (1987)
TRS calculations: T. Mylaeus et al., J. Phys. G 15, L135 (1989)
Coulomb energies calculated after S. Larsson, Phys. Scri 8, 17 (1973).
Plans for future measurementsPlans for future measurements
Recoil-beta-tagging: Search for Tz=-1 nuclei e.g.70Kr, 74Sr using double-beta-tagging
Study mirror symmetry in A=71 i.e. 71Kr Search for 0+ in 74Rb and compare B(E0) with 74Kr Use vacuum-mode recoil separator to select by mass and improve
rates
Recoil-beta-tagging: Search for Tz=-1 nuclei e.g.70Kr, 74Sr using double-beta-tagging
Study mirror symmetry in A=71 i.e. 71Kr Search for 0+ in 74Rb and compare B(E0) with 74Kr Use vacuum-mode recoil separator to select by mass and improve
rates
RBT CollaborationRBT Collaboration
B.S. Nara Singh1, A.N. Steer1, D.G. Jenkins1, R. Wadsworth1, P. Davies1, R. Glover1, N.S. Pattabiraman1, T. Grahn2, P.T. Greenlees2, P. Jones2,
R. Julin2, M. Leino2, M. Nyman2, J. Pakarinen2, P. Rahkila2, C. Scholey2, J. Sorri2, J. Uusitalo2, P.A. Butler3, M. Dimmock3, R. D. Herzberg3,
D.T. Joss3, R.D. Page3, J. Thomson3, R. Lemmon4, J. Simpson4, B. Blank5, B. Cederwall6, B. Hadinia6, M. Sandzelius6
Department of Physics, University of York, Heslington, York YO10 5DD, UK Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40351, Jyväskylä, Finland Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, UK CCLRC Daresbury Laboratory, Keswick Lane, Warrington WA4 4AD, UK Centre d’Etudes Nuclèaires de Bordeaux-Gradignan, F-33175 Gradignan Cedex, FranceRoyal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm, Sweden.
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