Lifetime Measurement in 103,104 Rh with RDDS Method in Inverse Kinematics: A Test for Nuclear Chirality. Suzuki Tomokazu

Transcription

1 Lifetime Measurement in 3,4 with RDDS Method in Inverse Kinematics: A Test for Nuclear Chirality Suzuki Tomokazu Research Center for Nuclear Physics, Osaka University T. Koike, G. Rainovski,3,T.Ahn 3,M.Carpenter 4,A.Costin 5, M. Danchev 4,A.Dewald 6, R.V. Janessens 4,C.J.Lister 4,O.Moler 6, N. Pietralla 3,T.Shinozuka 7, J. Timár 8,C.Vamman 9, R. Wadsworth,S.Zhu 4 Department of Physics, Tohoku University, Japan St. Kliment Oridski University of Sofia, Bulgaria 3 SUNY at Stony Brook, NY, USA 4 Argonne National Laboratory, IL, USA 5 University of Tennessee, TN, USA 6 University of Cologne, Germany 7 Cyclotron and RI Center, Tohoku University, Japan 8 ATOMKI, Hungary 9 NSCL, MI, USA University of York, UK April 3, 8 RIKEN

2 Introduction Gamma8 (RIKEN) April 3, 8 Criteria for Nucliar Chirality Nearly degenerate ΔI =twin bands with the same parity B(E :I I ) in,out and B(M :I I ) in,out values are the same or similar between both bands. From C.M. Petrache et. al. Phys. Rev. Lett. 96 (6) 5 out I+ out in in out I+ in out in out I I+ I+ I () j p L () j p R 38 Eu 4 Eu 63 6 The Best Configuration for mass region πg 9/ νh /. shortest axis of the triaxial shape j n ; neutron-particle inahigh-j n shell. longest axis of the triaxial shape j p ; proton-holl inahigh-j n shell 3. intermidiate axis of the triaxial shape R; core rotation R j n (3) () j n Figure from T. Koike et. al. Phys. Rev. Lett (4) () 3 Pr 3 La R (3) 36 Pm 35 Nd 34 Pr 3 La 35 Ce 34 La Cs 6 Cs 8 Cs 3 Cs 3 Cs

3 Chiral candidates in the mass region Gamma8 (RIKEN) April 3, 8 7 Ag Mo The doublet bands are built on πg 9/ νh / configuration for odd-odd nuclei πg 9/ νh / configuration for odd-a nuclei (broken pair of neutron) The energy degeneracy gets better from to 4 and then gets less to 6. The degeneracy is only -kev at the best in E E [MeV] BH EX Spin [ h ] Spin [ h ] 5 From C. Vamman et. al. Private Communication J. Timar et. al. Phys. Rev. C 73 3 (6) C. Vamman et. al. Phys. Rev. Lett (4) J. Timar et. al. Phys. Lett. B (4) P. Joshi et. al. Phys. Lett. B (4)

4 Chiral candidates in 3,4 Gamma8 (RIKEN) April 3, 8 3 πg 9/ νh / πg 9/ Energy [MeV] S(I) [kev/h] B(M)/B(E) [(µ N /eb) ] Band 3 Band Band 3 Band 4 Spin [h] Spin [h] From J. Timar et. al. Phys. Rev. C 73 (6) 3. C. Vaman et. al. Phys. Rev. Lett. 9 (4) Excitation Energy [MeV] S(I)=[E(I)-E(I-)]/I [kev/h - ] B(M)/B(E) [( /eb) ] m N Yrast Partner Yrast Partner Yrast:B(M)/B(E) Partner:B(M)/B(E) B(M) in /B(M) out B(M) in /B(M) out Spin [h - ]

5 3 and 5 Gamma8 (RIKEN) April 3, / 635 4/ 46 39/ / 37/ / 35/ / 35/ / 87 33/ / / 876 7/ / / 7/ / 3/ / 9/ / 9 7/ / / / 9/ / 43/ / 4/ 674 4/ / / / 58 37/ / / 33/ / / / / 863 7/ / / 7/ / 5 3/ / 76 9/ / 5/ / / / 7/ S(I)=[E(I)-E(I-)]/I [kev/h] Spin [h]

6 Coincidence Recoil Distance Doppler Shift Method (RDDS) Gamma8 (RIKEN) April 3, 8 5 d Stopper Beam Target (shift) (un-shift) C B L h Counts/.6keV shifted un-shifted shifted un-shifted shifted un-shifted Gated keV (shifted) (35 μm) (5 μm) (75 μm) τ i = A L i Lj dn i dt = λ in i (t) + X λ h n h (t)b hi h τ i = N P ij(t) +b ij h N hi(t) dn ij (t) I CA s,s τ i = I BA s,s I CA s,u (x) αicb (x + Δx) ICA dt I BA s,u (x) Δx (x + Δx) IBA s,s (x Δx) v s,u (x) Δx ICA s,s (x Δx),α = v I CB Energy (kev) From A. Dewald et. al. Z. Phys. A 334 (989) 63; G. Böhm et. al. Nucl. Inst. Meth. Phys. Res. A 39 (993) 48

7 GAMMASPHERE GSFMA69 Lifetime measurement of candidate chiral members in the A region Recoil Distance Doppler Shift Method (RDDS) GAMMASPHERE Ge detectors array Cologne universiry plunger device Inverse Kinematics Reaction (Large recoil velocity β.5) Reaction B( 96 Zr,xn) 4,3 (x=3,4) Beam E( 96 Zr) = 33MeV (from ATLAS accelerator at ANL) Trigger γ-γ 7 distances (8,5,3,35,5,75, μm) Zr B 3 μg/cm Nb β=5.4% 33MeV Target 4.5mg/cm d (fast) Nb 3mg/cm Degrader β=3.7% (slow) BGO Suppressor Plug Ge Detector Hevimet Shield γ γ γ Gamma-ray Source Gamma8 (RIKEN) April 3, 8 6 PM Tubes BGO Suppressor Shield Detector Electronics Liquid Nitrogen Dewar Support Hemisphere Front ring Back ring angle N det angle N det γ-γ matrices are created ring by ring for each distances.

8 Experiment result of 3 and calculated values of 5 Gamma8 (RIKEN) April 3, 8 7 B(M) [μ N ] B(E) [e b ] Level scheme From J. Timar et. al. Phys. Rev. C 73 (6) Spin (h) Level TAC for 5 Exp. for 3 Energy Spin ω B(E) B(M) B(E) B(M) (kev) (J π ) (e b ) (μ N ) (e b ) (μ N ) 363 5/ (4).3(4) 394 7/ (3).8() 43 9/ (4).(4) Routhian (MeV) y h (MeV) x θ z J Planar Chiral TAC Calc from J. Timar et. al. Phys. Lett. B 598 (4) 78 ω planar aplanar

9 Result for 4 Gamma8 (RIKEN) April 3, B(E) [e fm ] B(M) [μ ] Ν Spin [h] The B(M )/B(E) staggering has been observed in the previous experiment. This is suspected for chiral selection rule if the staggering is caused by B(M ) values. C. Vamman et. al. Phys. Rev. Lett. 9 (4) 35. However, the staggering is caused by B(E) staggering. The behavior of B(E) staggering is cannot be understood and needs theoretical interpretations.

10 Summary Gamma8 (RIKEN) April 3, 8 9 The lifetime of chiral candidates member in the 3,4 isotopes are measured. RDDS GAMMASPHERE 3 Three lifetimes related to chiral doublets are extracted. The experimental results are compared to TAC calculations for 5. TAC calculation indicates chiral doublet in the ω.55 region Three levels (.5 ω.35) were consisted with TAC calculations for 5. 4 Four lifetimes are extracted. The reported B(M )/B(E) seems staggering from B(E). In B(E) needs theoretical explanation.