A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Argonne National Laboratory Office of Science U.S. Department of Energy IPNS Third RF Cavity Status Report G.E. McMichael Accelerator Facilities Manager Presentation at the Ninth SHRF/LOIA Collaboration Meeting June 14, 2004

Pioneering Science and Technology Office of Science U.S. Department of Energy 2 IPNS ACCELERATOR OVERVIEW Accelerator delivers a short (70 ns) intense (3 x protons/pulse) pulse of 450 MeV protons to the depleted-uranium target 30 times per second Each proton produces about 15 neutrons IPNS is a user facility. Sole purpose of the accelerator is to produce neutrons (99% for the neutron-scattering instruments in Bldg. 375, remainder for an “exotic- beam” source for ATLAS)

Pioneering Science and Technology Office of Science U.S. Department of Energy 3 IPNS ACCELERATOR FACILITY Three accelerators in series -750 keV Preaccelerator -50 MeV Linac -450 MeV Rapid Cycling Synchrotron (RCS) Ancillary Systems -RF (Variable Frequency Beam Feedback controlled) -Magnets and power supplies (Pulsed & DC) -Control, diagnostics and data acquisition -Vacuum -Safety (Personnel & Equipment) Buildings and Utilities -AC Power -Water Systems -Air Conditioning

Pioneering Science and Technology Office of Science U.S. Department of Energy 4 HISTORY Preaccelerator and linac entered service in 1961 as injector to the 12.5 GeV ZGS (Zero Gradient Synchrotron) high-energy physics accelerator RCS developed in mid 1970's as a proposed booster for ZGS. Excess beam would have been available for a spallation neutron source ZGS was shut down in RCS initially ( ) provided beam into the ZING experimental target. First beam to IPNS target was in 1981 Eight-billionth pulse 16 April, 2004

Pioneering Science and Technology Office of Science U.S. Department of Energy 5 ION SOURCE & PREACCELERATOR Magnetron-type H - ion source, cesium getter Extraction at 20 keV, magnet to separate electrons Cockcroft-Walton generator, 750 Kv Output H - beam, 30 mA peak, 70 µs pulses, 30 Hz

Pioneering Science and Technology Office of Science U.S. Department of Energy 6 LINAC Alvarez-type “drift-tube linac” Copper-clad steel tank, 33.5 m long, 0.93 m diameter 124 drift tubes, each with a dc quadrupole magnet 200 MHz rf transmitter, triode amplifier tube, 3.5 MW Output H - beam 50 MeV, 10 mA peak, 70 µs pulses, 30 Hz

Pioneering Science and Technology Office of Science U.S. Department of Energy 7 8 Dipole horizontal bending magnets 6 Dipole vertical steering magnets 16 Quadrupole focusing magnets 12 Wire scanners, 6 Beam position monitors Transports H- beam ≈ 40 m from linac to RCS 50 MEV TRANSPORTATION LINE

Pioneering Science and Technology Office of Science U.S. Department of Energy 8 RAPID CYCLING SYNCHROTRON “ RCS” 43 m circumference strong-focusing, combined-function synchrotron 6-sector machine, magnet structure D00FDF0 Betatron tune correction provided by two pairs of sextupole magnets Multi-turn injection (  130 turns, “3 mile string”) Single-turn extraction by two ferrite- loaded kicker magnets and two septum magnets

Pioneering Science and Technology Office of Science U.S. Department of Energy 9 RAPID CYCLING SYNCHROTRON “ RCS” Ring magnets are part of a biased 30 Hz resonant circuit. Generate a magnetic field that varies from 0.28 to 1 Tesla during the accelerating cycle Thin carbon foil strips off the two electrons Two rf cavities to bunch and accelerate the proton beam Third rf cavity will be installed in L6 section Output proton beam 450 MeV, ns pulse, 30 Hz, 3 x protons/pulse

Pioneering Science and Technology Office of Science U.S. Department of Energy 10 PTS BEAMLINE 4 Dipole horizontal bending magnets 2 Dipole vertical steering magnets 15 Quadrupole focusing magnets 6 Segmented secondary emission monitors, 1 Segmented wire ion chamber Transports H- beam ≈ 45 m from RCS to neutron-generating target

Pioneering Science and Technology Office of Science U.S. Department of Energy 11 ACCELERATOR OPERATIONS OPERATING PERIODS Typically two to four weeks on and one to two weeks off Six-hours reserved each Tuesday for machine research and moderator regeneration Two longer shutdowns (Christmas and summer) for installations and larger maintenance jobs

Pioneering Science and Technology Office of Science U.S. Department of Energy 12

Pioneering Science and Technology Office of Science U.S. Department of Energy 13 THIRD RF STATION Cavity almost identical to two existing Redesigned rf amplifier systems: -Pre-driven and final use new tubes -Driver is an updated version of existing systems -New low-level system Provide second-harmonic rf for capture and initial acceleration Provide additional fundamental at mid-cycle Can function as on-line spare for existing fundamental systems Installation to start in 6 months

Pioneering Science and Technology Office of Science U.S. Department of Energy 14 2 nd – HARMONIC RF Propose to enhance 3 rd rf system to operate at 2 nd harmonic throughout the acceleration cycle Principal addition will be a new cavity with different ferrite Funding and schedule uncertain

Pioneering Science and Technology Office of Science U.S. Department of Energy 15 SUMMARY IPNS continues to have a moving 10-year window – to ensure reliable operation for the next 10 years Recent budget problems have slowed the upgrade/assurance program. Our interest in the collaboration remains strong - Shaoheng Wang will be joining our program