The RAL Front End Test Stand David Findlay ISIS Accelerator Division Rutherford Appleton Laboratory Oxfordshire, UK STVLTVS EST QVI ACCELERATORIBVS CVRANDIS VICTVM QVAERIT

2 2 CCLRC Council for the Central Laboratory of the Research Councils Member of RCUK (Research Councils UK) BBSRC, CCLRC, EPSRC, ESRC, MRC, NERC, PPARC Provides large facilities for UK science Lasers, neutrons, synchrotron radiation BBSRCBiotechnology & Biological Sciences Research Council CCLRCCouncil for the Central Laboratory of the Research Councils EPSRCEngineering & Physical Sciences Research Council ESRCEconomic & Social Research Council MRCMedical Research Council NERCNatural Environment Research Council PPARCParticle Physics & Astronomy Research Council

3 3 Rutherford Appleton Laboratory ISIS Diamond Daresbury Laboratory SRS 4GLS CCLRC

4 4 ISIS ~270 people total Accelerator Division (~95) Diffraction & Muons Division Instrumentation Division Spectroscopy & Support Division Target Division David FindlayPhotonuclear physics / light nuclei Photofission Radioactive waste Accelerator services Gemstones (in private sector) Medical sterilisation (in private sector) ISIS

5 5 Why a [proton driver] front end test stand? Prove key elements of high power proton accelerators Applications of a RAL test stand Generic Spallation neutron sources Neutrino factories Transmutation machines Tritium generators Energy amplifiers Training / Young people / Real hardware Specific ISIS upgrades UKNF UK academic accelerator community

6 6 ISIS World’s leading spallation neutron source Natural wish to stay at or near front Upgrade strategies / CCLRC funding / ASTeC (ASTeC = CCLRC’s Accelerator Science & Technology Centre) UK Neutrino Factory Strong drive from UKNF community PPARC support for proton driver R&D Synergies with possible ISIS upgrades UK academic community Imperial College - CCLRC joint appointment Lecturer / Senior Lecturer in Accelerator Science Extend university accelerator centres to protons

9 9 What’s in a front end? Ion source, LEBT, RFQ and beam chopper Why does it matter? Where beam quality set for entire machine What has to be tested? New, high performance ion sources, RFQs, beam choppers ISIS 0.16/0.24 MWNow PSI 0.75 MW[not pulsed] SNS 1 MWNear future JPARC 1 MWNear future NF 4 MW — a big step!Further away [ISIS 1, 2, 5 MWPlans]

10 So, planning to build front end test stand at RAL But already had one!

12 ISIS RFQ Test Stand RFQ to replace ISIS Cockcroft-Walton MHz, 4-rod, 35 keV i/p, 665 keV o/p 50 mA / 10% DF design, 30 mA / 2% DF use Test stand built to characterise and soak test Met specifications Soak tested successfully for >2000 hours

19 Proton driver front end test stand at RAL ISIS Accelerator DivisionCCLRC/ASTeC Imperial CollegePPARC Warwick UniversityPPARC + ? + 1½ × ½ SY/year EU (HPRI-CT ) + 5 × ½ SY/year EU (HIPPI/CARE/ESGARD) Mike Clarke-Gayther, Dan Faircloth, Frank Gerigk, Paul Harrison, Alan Letchford, Ken Long,...

20 Relationship with CERN test stand Formal cooperation through HIPPI Two approaches to beam chopper But different CERN test stand for Linac4 then SPL Proton / H – ion sources RAL test stand more generic Differences reflect organisation’s missions

21 RFQ 234 MHz Bunch + accel- erate Chopper Switch in 2 ns for ~0.1 ms LEBT Match ion source to RFQ H – ion source 60 mA 2 ms Beam stop Diagnostics Transverse emittances, energy & energy spectra, bunch widths, halo,... Block diagram of RAL front end test stand 75 keV2½ – 3 MeV

22 H – ion source — Development to ~60 mA required Based on ISIS H – ion source (35 mA) LEBT — Revision of ISIS RFQ LEBT probably sufficient RFQ — Base on ISIS & ESS 4-rod RFQs ISIS RFQ designed for 10% RF duty factor cf. ISIS 2% 75 keV in, 2½ – 3 MeV out, MHz Most expensive item: ~1 – 2 MW RF driver Beam chopper — Development required Based on ESS concept But need ion source, LEBT and RFQ to test beam chopper

Ion source development rig (ISDR) at RAL

H – ion source R&D programme — for future high power proton accelerators (e.g. for future spallation neutron sources) — × ~10 output required 1 inch Important milestone passed Successful thermal modelling of world leading ISIS ion source — extraction of surface temperatures Excellent agreement between calculated and measured thermocouple temperatures Anode 200°C Ab initio calc.Meas.°C Anode t/c – 600 Cathode t/c Body t/c °C Cathode

Close-coupled chopper module 1145 mm Slow switch Fast switch Beam Buncher cavity

Beam chopper R&D programme — specialised hardware — fast, high voltage pulser specified and procured 1½ kV rise in <2 ns

28 RAL front end test stand for: ISIS upgrade Front end of 180 MeV linac MHz DTL to ~80 MeV MHz SCL to 180 MeV (like Linac4 at CERN) UK neutrino factory High power proton accelerators in general

29 New ~180 MeV linac Present 70 MeV linac ISIS half-megawatt upgrade

30 UK Neutrino Factory New ~180 MeV linac

31 With existing funding, at end of three years, i.e. by March 2007, expect to have Dedicated area (in R8 (probably)) Lead shed (shield against RFQ X-rays) Support structure / Stands Operational ~60 mA H – ion source available LEBT assembled Design for RFQ Specification for RF driver Proven electrical design for beam chopper Design for quadrupoles and cavities for chopper Specification of diagnostics

R8

R8, area easily available 290 m² More space available 5 m 12 27½ ½1½ 4½4½ ½5½ 7 RFQChopperDiagnosticsLEBTIon source RF driver area Mag. spectr.

36 Opportunities to take advantage of: Area in R8 already well provided — space, electricity, water, air, crane, loading bay, on main ISIS controls circuit, … Significant existing hardware — high power arc driver and high power extraction pulser for H – ion source, TMPs, gas scattering spectrometer, magnetic spectrometer, emittance scanners, data acquisition systems, 200 kW RF driver,...

– 2007 Overall scheme, design, infrastructure, specifications, some hardware  2007 Complete scheme Hope to demonstrate high quality chopping of ~60 mA H – beams at ~2½ MeV [End]

Novel gas scattering energy spectrometer at RAL

Surface barrier detector + Cs 137 conversion source

Experimental ion source and assembly

RAL beam chopper design Robust design with explicit provision for high power beam collection Slow transmission line Lumped line — thermally hardened ns 8 ns Up to 100 µs