High resolution study of TZ= +3 → +2 Gamow-Teller transitions in the 50Ti(3He, t)50V reaction Gülfem SÜSOY DOGAN Istanbul University Science Faculty, Department of Physics

Outline Charge Exchange (CE) reactions at intermediate energies: a tool for extracting Gamow-Teller strengths Importance of Gamow-Teller Transitions Pionering studies of GT strengths in pf-shell nuclei Recent results of CE experiments with ionized 3He beams – 50Ti(3He,t) reaction at 140 MeV/u, RCNP. Conclusion

CE Reactions: type of direct reactions CE Reactions at Intermediate Energies: a tool for extracting Gamow-Teller strengths A proton (neutron) enters the nucleus, but emerges as a neutron (proton) “exchanging charge” with one of the nucleons CE Reactions: type of direct reactions Direct reactions are often described as “surface” reactions incident and target nuclei, interact is very much shorter than the life of a corresponding compound nuclei occurring very rapidly (on the order of 10-22 seconds)

B (Op) ~ (matrix element)2 = |< f | Op | i > |2 (p,n) ve (3He,t), (t,3He), (n,p)... CE reactions that make transitions in the β- and β+ direction performed at 0° and intermediate incoming beam energies are good tools to study the στ response of nuclei and they have features complementary to β decay. T.N. Taddeucci et. al., NPA469 (1987) 125. REDUCED TRANSITION STRENGHTS B (OP ) B (Op) ~ (matrix element)2 = |< f | Op | i > |2 Exp: B(GT), B(F), B(M1), B(E2), …

1p-1h & 1p-1p Configurations If a proper amount of energy is given to a nucleus, the simplest excitation that can happen is 1p-1h type. 1p-1p excitations has an attractive nature 1p-1h excitations has a repulsive nature

Purposed study: analysis of all Ti isotopes to discuss B(GT) distributions Tz = 1 Tz = 3/2 Tz = 2 Tz = 5/2 Tz = 3 p-p p-h p-h p-p p-h p-p p-h p-p p-h h-h As A increases, they gradually loose the nature and acquire the proton particle – neutron hole nature. We see that they have almost pure nature in 50V.

High resolution brings higher quality! Pionering studies of GT strengths in pf-shell nuclei (p,n) (3He,t) 100-200 MeV/nucleon enegy 0° scattering angle ~300 keV Resolution Total B(GT) values RCNP Research Centre 140 MeV/nucleon energy 0° scattering angle Ring Cyclotron WS Beam Line GR Magnetic Spectrometer Matching Techniques ~35 keV Resolution Individual B(GT) values High resolution brings higher quality!

50Ti(3He,t) 50V 50V ENEGY SPECTRUM 420MeV 0°Scattering angle In order to achieve high resolution High-quality 3He beam Grand-Raiden (GR) Magnetic Spectrometer Dispersion-matching techniques count

B(GT) Distributions in 50V The Ikeda sum rule for GT strenghts in nuclei is expressed by; Since the neutron excess in the target nucleus 50Ti is 6, the value 3(N-Z) is 18. Total sum of B(GT) strength experimentally up to 13.5 MeV is 6.8, that is 38% of 18. It is expected that the strength ΣB+(GT) (the strength in the (n,p) direction and thus the T = T0+1 = 4 strength) is small. Therefore, our result suggest that the total sum of the B-(GT) strength is less than half of the sum-rule limit value.

Analysis Continues Analysis Continues

Conclusions In 50Ti spectrum energy resolution of ~21.5 keV was achieved and the discrete states were observed up to 13.5 MeV. The experimental energies were extracted with 5% energy difference. It is expected that they can be used for the understanding of B(GT) distribution among the isotopes. By using high resolution (3He,t) reactions, the project to obtain B(GT) distributions in the pf-shell nuclei is in progress.

SPEACIAL THANKS TO... PROF. YEŞİM ÖKTEM PROF. YOSHITAKA FUJITA PROF. BAKİ AKKUŞ DR. HIROHUKO FUJITA