Target Activation Study

1. Target Activation Study Paul Hodgson The University of Sheffield

2. Introduction • Want to have some idea of how active the MICE target will become when operating in ISIS beam. • Use FLUKA general purpose Monte Carlo as it can be used for arbitrary particle-target configurations and energies

3. Target geometry • The target is modelled as a thin slab of titanium with dimensions 35mm × 10mm × 1mm • The beam is assumed to be incident on the target 15 mm from the base • The beam consists of 800 MeV protons only • For the purposes of this study the target was assumed to interact with 1.4 × 1012protons per second and operated for two 8 hour shifts per day

4. Radionuclide production • The simplest thing FLUKA gives is the radionuclide production per incident proton

5. Activation • During 2008 target operation the target was pulsed for a total of 185207 times in ISIS beam • The target pulsed at 0.4 Hz • The target did not interact with anything like 1.4 × 1012 protons • No significant activation of target expected (or seen) • But if we assume “normal” operation and some irradiation/cooling sequence we can estimate likely activation

6. Activation • The ISIS run schedule used for irradiation/cooling periods within FLUKA • Investigate 2 irradiation scenarios • Remove target after one 38 day irradiation and cool • Target is exposed to the full cycle of operations • Calculate activation for various cooling times • 1 hour, 1 day, 1 week, 1 month, 1 year and 10 years

7. 38 Day irradiation

8. Full 2008 run Schedule

9. Uncertanties • In order to give confidence in the accuracy of the results obtained with FLUKA two experimental studies of protons on titanium were examined and compared with FLUKA Worst case is a factor of 2

10. Conclusions • Estimated radionuclide production in target per incident proton • Used FLUKA to get an idea of the likely activation of the target • Checked validity of estimates using other experimental results • See agreement within a factor of two