1. Problematic Yttrium reaction 25/02/2019
In case of 89Y(n,3n) 87Y reaction the ground and isomeric states are produced simultaneously
T1/2=13,38h E=380,79 keV
89mY
9/2+
89Y (n,3n) 87Y
reaction
beta +, e+
89Y
T1/2=79,8h
1 /2-
For determination of 87Y ground state production it is necessary to involve87mY decay to the ground state….
25/02/2019
Yttrium reaction

2. Intensity of used gamma-line
Context
Why have we choose Yttrium ?
Products of (n,3n) reactions on yttrium are well known
Half-lives of yttrium isotope are enough long for γ-spectrometry
γ-transitions are intensive enough for detection and good
separation from each other
For example the decay of gold provides a light energy gamma ray around 411keV where as the decay of zinc give us a high energy gamma-rays equals to 1115keV. High energy gamma-rays could cross over the detector without interact with it. In that case, the efficiency goes down. Nevertheless it is not the only explanation because for high energy gamma-rays, the probability of pair–creation becomes high.
Photon transforms into an electron-positron pair.
Reaction
Threshold energy
[MeV]
Half-life
Used gamma-line
[keV]
Intensity of used gamma-line
[%]
89Y (n,3n) 87mY
21,6
13,37h
380,8 78
25/02/2019
Yttrium reaction

3. Decay of Yittrium 87 isomeric state
Decay of 87Y and 87mY
Decay of Yittrium 87 isomeric state
0 < t < t(irradiation)
t >t(irradiation)
25/02/2019
Yttrium reaction

4. Decay of Yittrium 87 isomeric state
Decay of 87Y and 87mY
Decay of Yittrium 87 isomeric state
End of irradiation
25/02/2019
Yttrium reaction

5. Decay of Yittrium 87 ground state
Decay of 87Y and 87mY
Decay of Yittrium 87 ground state
0 < t < t(irradiation)
t >t(irradiation)
25/02/2019
Yttrium reaction

6. Decay of Yittrium 87 ground state
Decay of 87Y and 87mY
Decay of Yittrium 87 ground state
End of irradiation
25/02/2019
Yttrium reaction

7. Decay of 87Y and 87mY Yttrium reaction 25/02/2019
Yittrium 87 ground and isomeric state until the end of irradiation
Curve almost similar between them
End of irradiation
25/02/2019
Yttrium reaction

8. Decay of Yittrium 87 ground and isomeric state
Decay of 87Y and 87mY
Decay of Yittrium 87 ground and isomeric state
End of irradiation
25/02/2019
Yttrium reaction

9. Hypothesis and results
Pg = Pm = constant = 1e10
The velocity of production P is connected to neutron flux.
Thus it seems logical to put in correction into equations. (neutron flux not always identical)
At the time t=t(end of irradiation)= 7200 seconds and for Pg=Pm
In case of the time of irradiation is infinite, this is the extreme value that the number of nucleis in ground state could reach.
25/02/2019
Yttrium reaction