Alternative production routes and new separation methods for no-carrier-added 163 Ho

1. Alternative production routes and new separation methods for no-carrier-added 163Ho Susanta Lahiri, Moumita Maiti Saha Institute of Nuclear Physics, Kolkata, India & ZoltánSzűcs, SandorTakacs Institute of Nuclear Research of H.A.S. Debrecen, Bem tér 18/C HUNGARY

2. 163Ho: How to produce?

3. Proton induced reaction Calculations by Maiti et al. natDy(p,xn) 163Ho σ ~350 mb at 19 MeV Contributors: 163Dy (24.9%)(p,n)163Ho (σ~0.4 mb) 164Dy (28.2%)(p,2n)163Ho (σ~1254mb)

4. Calculations by Szucs et al. Main reaction: 163Dy(p,n)163HoSide reactions: 158Dy)p,2n)157Ho→157Dy→157Tb 160Dy(p,2n)159Ho→159Dy 160Dy(p,2p)159Dy 156Dy(p,3n)154Ho→154Dy 161Dy(p,a)158Tb Radiochemical separation of 163Ho is recommended!163Dy(p,a)160Tb Enriched target material is preferable!

5. Theoretical cross sections of163Dy(p,n)163Ho and 163Dy(d,2n)163Ho Calculations by Szucs et al.

6. Cross section curvesof the potential nuclear reactions Calculations by Szucs et al.

7. Thick target yields and prices of target materials Calculations by Szucs et al.

8. Contaminating isotopes Calculations by Szucs et al.

9. Irradiation of natDy by proton Calculations by Szucs et al.

10. Comments The highest yield give the (p,2n) reaction Er irradiation is NOT preferred because of the side reactions, producing the stable 165Ho as well as the radioactive 166Ho!!!! The enriched target of 164Dy has to be used. In other case during the irradiation of the natDy the 157-158Tb and 159Dy will give us extremely high contamination During the irradiation of enriched 164Dy we will get the stable 165Ho too by the 164Dy(p, γ)165Ho reaction. However this amount is 2 magnitude less, than 163Ho. The calculation of cross section curve of 157Tb contains all possible reaction for 157Ho, 157Dy and 157Tb, as well as for 159Dy also contains all possible reaction for 159Ho and 159Dy. Due to the 10 times higher yield of the (p,2n) reaction than the (p,n) reaction not necessary 1800 hours irradiation time to get 1 MBq 163Ho, approximately. Looks that is enough 180 hours, 10 times less, therefore the irradiation cost in cyclotron also can be 10 times less, it means that is 50kEuro, approximately, which is comparable with the irradiation on reactor!!!!! The Debrecen cyclotron can't produce the 30MeV proton beam.

11. IrradiationParameters: (i) Projectile – p, (ii) Ep = 19 MeV, (iii) current: 700 nA, (iv) time of irradiation: 10 h Two targets were irradiated in stack with the following configuration p+ Dy2O3 • There is no way to monitor Ho-163 by monitoring its nuclear properties. • Separation of Dy and Ho is difficult. • Very long time is required to rich the saturation activity.

12. -induced reactions natDy(α, xn) 163Er () 163Ho Calculations by Maiti et al.

13. +Dy2O3 • Irradiation parameters: • Projectile : α • EP = 40 MeV • first target: 1 µA, 7 h irradiation • second target: 3 µA, 11 h irradiation natDy(α, xn) 163Er () 163Ho (σ ~500 mb at 40 MeV) Exhaustive Chemistry !! Experiment and Calculations by Maiti et al.

14. RadioChemical Separation of Er and Dy Technique – Liquid liquid extraction Reagents: di-(2-ethylhexyl) phosphoric acid (HDEHP) dissolved in cyclohexane (Organic phase) & HCl (aqueous phase) 161Er was used as monitor of Er in the radiochemical separation & Dy was measured by ICP-OES HCl : 0.2 M & HDEHP 1% Extraction: Dy 48.8% Er 84%

15. Separation scheme Experiment by Maiti et al.

16. Li-induced reaction 159Tb(7Li, 3n) 163Er (σ ~312 mb at 31 MeV) Calculations by Maiti et al.

17. Irradiation Irradiation parameters: (i) Projectile – 7Li (ii) EP = 31 MeV (iii) current: 150 nA (iv) time of irradiation: 11 h No successful results have been achieved using HDEHP

18. Calculation for natDy(p,xn) reaction: Maiti et al. For a sample thickness: 4 mg/cm2 No. of 163Ho (via 163Er) will be = 2.5x1010 atoms/A-h For enriched target it will increase by factor of 2. For 10 A, 100 h irradiation (one target): 2.5 x 1013 atoms

19. Calculation for Dy(,xn) reaction: Maiti et al. For a sample thickness: 4 mg/cm2 No. of 163Ho (via 163Er) will be = 2x1010 atoms/A-h In 6 h, irradiation time = 1.2x1011 atoms 20 A current, 5 targets in a row, 6 h irradiation time 1.2 x 1013 atoms

20. Calculation for 159Tb(7Li,3n) reaction: Maiti et al. For a sample thickness: 4 mg/cm2 No. of 163Ho (via 163Er) will be = 4x109 atoms/A-h In 6 h, irradiation time = 2.4x1010 atoms 20 A current, 5 targets in a row, 6 h irradiation time 2.4 x 1012 atoms

21. Consequences! • 163Ho can be produced by charged particle activation through direct or indirect way • However, separation of Ho from the target matrix is extremely difficult due to the similar chemical properties of lanthanides • Therefore, it needs special attention towards the purification procedure • In order to ensure the production of 163Ho nuclear properties can not be exploited as it behaves like stable isotope

22. ECHo Collaboration This collaboration has been formed on 29th June, 2012 Thank you…. Participants: 10 Institutes from 5 countries

24. Future Plan from SINP and ATOMKI Group Will apply for beam time in VECC, Kolkata and in Atomki, Hungary Verification of theoretical data as much as possible. Storing Ho-163 for future use Development of new separation techniques based on HPLC