ISIS OPTIMVS NEVTRONVM SPALLATIONENSIVM FONS MVNDI ISIS Developments David Findlay Accelerator Division ISIS Department Rutherford Appleton Laboratory

2 2 ISIS — world’s leading spallation neutron source But ISIS accelerators primarily a neutron factory ~800 experiments/year ~1600 visitors/year Output and reliability are key quantities

ISIS from air

5 5 ISIS outline 17 kV H – ion source 35 kV DC gap 665 keV RFQ— new 70 MeV drift tube linac 800 MeV proton synchrotron— new 2RF Target station 1— 50 pps at present 40 pps when TS-2 running Target station 2— 10 pps— new Obsolescence mitigation— on-going

amp-hours delivered on 12 December ,000 C 2.25E+23 protons 4.4E+24 neutrons 7.5 g neutrons ~£30M/g

202½ MHz 4-rod RFQ LEBT Ion source

RFQ rods + stems assembly

Old Cockcroft-Walton

2RF: High power driver Cavity

Four 2RF cavities in Straights 4, 5, 6 & 8

4 × 200 – 2000 A cavity bias regulators

4 × 20 kV, 10 A anode power supplies

14 Obsolescence mitigation Replacing ageing equipment E.g. the NINA big choke linac RF systems extraction fast kickers...

Old and new chokes for synchrotron main magnet power supply

Extraction kickers: 5000 A, 100 ns rise time

Tantalum wire shock tests for neutrino factory target

Tantalum wire during and after pulsing

19 Aim of RFQ + 2RF: 200 µA → 300 µA New beam dynamics régime in synchrotron Commission 2RF with beam— Andy Seville Beam losses— Steve Payne Diagnostics— Ben Pine