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 × 10 12 protons 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 NuclideHalf-lifeProduction per p-p 48 V16d5.95 × 10 -6 45 Ti3.08h6.84 × 10 -5 48 Sc43.7h2.28 × 10 -5 47 Sc3.35d2.44 × 10 -4 46 Sc83.81d7.17 × 10 -5 44 Sc2.44d5.47 × 10 -5 43 Sc3.9h3.15 × 10 -5 47 Ca4.54d1.64 × 10 -6 41 Ca10300y6.48 × 10 -5 43 K22.3h1.20 × 10 -5 28 Mg21.0h1.02 × 10 -6 24 Na14.95h3.93 × 10 -6

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 × 10 12 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 PeriodBeam on (days) Beam off (days) 13825 23839 33839 43825 538cooling

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