1. 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

2. 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

3. 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 seconds)

4. 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), …

5. 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

6. 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.

7. High resolution brings higher quality!
Pionering studies of GT strengths in pf-shell nuclei
(p,n)
(3He,t)
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!

8. 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

9. 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.

10. Analysis Continues
Analysis Continues

11. Conclusions
In 50Ti spectrum energy resolution of ~21.5 keV was achieved and the discrete states were observed up to 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.

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