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 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 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 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 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 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

Building R8 — being reconfigured for FETS

FETS builds on experience from ISIS RFQ test stand

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 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

Good extraction over 1.75 ms arc at 50 pps

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

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

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

4-rod RFQ has at least one operational advantage

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 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 Radiation shielding 60 mA, 2 ms, 50 pps, 3 MeV into copper  2 – 3 × 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 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