1. The RAL Front End Test Stand David Findlay for Alan Letchford Accelerator Division, ISIS Department Rutherford Appleton Laboratory HIPPI-05, Cosener’s House, Abingdon, 28–30 September 2005

2. 2 2 RAL Front End Test Stand (FETS) Part of CCLRC’s generic R&D programme on high power proton accelerators Specifically, demonstration of some key technologies for the front ends of Spallation neutron sources Neutrino factories Waste transmuters Tritium production Energy amplifier

3. 3 3 FETS is a collaborative effort amongst CCLRC RAL ISIS CCLRC ASTeC Intense Beams Group Dept. Physics, Imperial College, London Dept. Physics, University of Warwick Promotion of accelerator science in UK universities

4. 4 4 FETS collaborators John Back, Giulia Bellodi, Mike Clarke-Gayther, Dan Faircloth, Graham Gosling, Stephen Jolly, Ajit Kurup, Alan Letchford, Eddie McCarron, Ben Pine, Dan Ciprian Plostinar, Jürgen Pozimski, Peter Savage, Mark Whitehead, Trevor Wood

5. 5 5 FETS funding CCLRC, through ASTeC ISIS and ASTeC staff + hardware PPARC, through ASTeC UK university staff CCLRC, through Infrastructure Fund Reconfiguration of test stand area EU, through HIPPI programme

6. 6 6 RFQ Chopper FETS main components: High brightness H — ion source Magnetic LEBT High current, high duty factor RFQ Very high speed beam chopper Comprehensive diagnostics RFQ Chopper

8. Building R8 — being reconfigured for FETS

9. FETS builds on experience from ISIS RFQ test stand

11. 11 FETS specification 60 mA H —, 2 ms, 50 pps 75 keV 3-solenoid LEBT 3 MeV, 324 MHz RFQ 2 ns chopping Comprehensive diagnostics Test stand in practice

12. 12 H — surface Penning ion source 35 mA, 200 µs (ISIS)  60 – 70 mA, 1 – 2 ms Increase largely achieved Separate Penning field Thermal modelling Electromagnetic modelling Extensive experimental work on dedicated ion source development rig

14. Good extraction over 1.75 ms arc at 50 pps

15. 15 3-solenoid magnetic LEBT Design proceeding well Beam chopper [Other talks]

16. 16 RFQ — 3 MeV, 324 MHz Ready availability of Toshiba E3740A 3 MW pulsed klystron (J-PARC) Electromagnetic DTL quadrupoles

17. 17 RFQ beam dynamics at 324 MHz encouraging 3 MeV, 4 metre design 95% transmission, 80 kV electrode voltage Low voltage design  4-rod type possible 4-rod and 4-vane designs being investigated

19. 4-rod RFQ has at least one operational advantage

20. 20 Diagnostics Full suite of diagnostics to maximise the experimental capabilities Beam currents Emittances Energy spectra (magnetic + gas scattering spectrometers) Non-destructive laser/optical Residual gas ion spectroscopy

21. 21 Possible beam halo monitor? Activate scandium annulus? 45 Sc(p,n) 45 Ti E thresh 2.8 MeV, 45 Ti t ½ 3 hours, 85% β + decay Low background 2.5 mA mean, 10 —5 halo, 100 seconds → 30 Bq Sc melts 1540°C

22. 22 Radiation shielding 60 mA, 2 ms, 50 pps, 3 MeV into copper  2 – 3 × 10 10 neutrons/second  ~100 mSv/hour at 1 metre Say lose 3%  ~1 mSv/hour at 2 metres ~1 metre concrete  ~1 µSv/hour C (graphite) or Al(-Si alloy) for beam dump? C: 13 C(p,n) threshold 3.00 MeV ( 13 C (1.1%)); 10-minute 13 N from 12 C (p,γ) Al-Si: (p,n) > 5 MeV; no activity from (p,γ)

23. 23 Conclusions RAL Front End Test Stand will make an important contribution to HPPA R&D Good progress from RAL/ISIS, ASTeC, Warwick and Imperial Builds on experience gained with ISIS RFQ pre-injector upgrade First LEBT beam anticipated for 2006