Facility Developments Georg Bollen Michigan State University

Outline Rare (Radioactive) Isotope Beam Facilities Challenges in next generation rare isotope beam production High-power targetry, isotope separation Maximizing science opportunities with rare isotope beam manipulation Beam stopping, cooling bunching, polarization, charge breeding Reacceleration (Instrumentation) Making best use of rare isotope production Isotope harvesting for applications Multiuser operation G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beams Facilities Based on Accelerators Many Challenges in Common G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Production ISOL production Protons, 1 GeV neutrons, photons, … MS Target Heavy ions, <2GeV/u >100 MeV/u 0.1 -20 MeV/u MS Re-acceleration 60 keV Ion source High intensity, good beam quality, low energy Ready for “stopped beam “ experiments (traps, lasers) and reacceleration Not all elements possible, decay losses Fast beam fragmentation and in-flight separation Beam Stopping Thermalization No chemistry involved, fast, universal production High beam energy – high sensitivity (single-particle ID) Lower intensity, large beam emittance G. Bollen, FRIB-China WS, 28 May 2015

Challenges in Rare Isotope Beam Production Increasing rare isotope beam rates and beam purity Higher power accelerators High resolution separators High power challenge High power densities – need for suitable materials and advanced technical approaches Radiation damage in materials – lifetime of targets Safe facility operations High beam purity challenge Multi-stage separators High-intensity beam cooling Selective ion sources (ISOL) Example FRIB fast beam rates G. Bollen, FRIB-China WS, 28 May 2015

Fast, Stopped, and Reaccelerated Beams for Broad Science Opportunities Fast beams (>100 MeV/u) Farthest reach from stability, nuclear structure, limits of existence, EOS of nuclear matter Stopped beams (0-100 keV) Precision experiments – masses, moments, symmetries Reaccelerated beams (0.2-20 MeV/u) Detailed nuclear structure studies, high-spin studies Astrophysical reaction rates Advanced beam manipulation is needed to make best use of the rare isotopes produced G. Bollen, FRIB-China WS, 28 May 2015

High-power Rare Isotope Production FRIB Superconducting RF Driver Linac Accelerate ion species up to 238U with energies of no less than 200 MeV/u Provide beam power up to 400kW Energy upgrade to 400 MeV/u for 238U by filling vacant slots with 12 SRF cryomodules G. Bollen, FRIB-China WS, 28 May 2015

Accelerator Technical Challenges Example: Charge Stripping of Intense Heavy Ion Beams High specific power loss of heavy ions in matter Solid stripper not an option (10 MW/cm3 power density) Fast liquid metal film, plasma stripper are options Liquid Lithium Film Charge Stripper Liquid lithium film established with controllable thickness and uniformity Liquid lithium film (10 mm thick) moving at ~50 m/s speed to remove deposited heat Beam power tests on liquid lithium film successfully performed at ANL The film sustained ~200% of FRIB maximum power density deposition G. Bollen, FRIB-China WS, 28 May 2015

High-power Rare Isotope Beam Production FRIB Fragment Separator Three-stage magnetic fragment separator High acceptance, high resolution to maximize science Multi-slice rotating graphite target Water-filled rotating beam dump Radiation resistant magnets New approaches and advanced techniques needed G. Bollen, FRIB-China WS, 28 May 2015

High-power Rare Isotope Beam Production High-power Production Target for FRIB 100 kW beam power loss 1 mm beam spot  60 MW/cm3 for 238U Multi-slice rotating graphite target 5000 rpm, 30 cm diameter Tmax =1900 C, Pmax/slice=10 kW Target concept successfully validated Graphite heavy ion irradiation studies at GSI/Germany High power electron beam tests at BINP/Russia Many common challenges in high-power targetry G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Production Achieving High Beam Purity and Large Acceptance Fast beams: multistage fragment separator with different optics modes ISOL: beam cooling (buffer-gas filled RFQ ion guides) + high-resolution mass separator Example 78Ni G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Manipulation Maximize Science Opportunities Preparing high-quality beams tailored to experiment’s needs Leverage advantages of fast beam production – provide high quality rare isotopes at a broad range of energies Beam Stopping Leverage advantages of fast beam production s Provide beams from fission sources, fusion reactions Beam Cooling and Bunching Low-emittance beams with tailored time structure Charge Breeding and Reacceleration Lower-energy rare isotope beams with high-quality G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Manipulation Major Topic at Recent EMIS Conference International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) Grand Rapids, MI, May 11-15, 2015 G. Bollen, FRIB-China WS, 28 May 2015

Beam Stopping Beam stopping - conversion of fast beams into low-energy beams In place or planned at all fast-beam facilities Used for stopping of fission fragments and fusion-evaporation reaction products Beam stopping in gas Linear gas stoppers developed at ANL, RIKEN, MSU, KVI, GSI, … Challenges are high beam rates (> 108/s) and light ions Solid stopper/reionizer Special elements, highest beam rates G. Bollen, FRIB-China WS, 28 May 2015

Beam Stopping Significant Development Potential Multifaceted approach Linear gas stopper (heavier ion beams) Cyclotron gas stopper (lighter ion beams) Solid stopper (certain elements, highest intensity) Cyclotron gas stopper Magnet construction complete and energized Ion transport and extraction techniques demonstrated Cryogenic linear gas stopper Higher beam purity, faster extraction, higher beam rates Advanced Cryogenic Gas Stopper (ACGS) project funded and underway G. Bollen, FRIB-China WS, 28 May 2015

Beam Stopping Advances in Low-Energy RF Ion Transport Techniques Ion surfing using traveling waves provides fast ion transport in gas “Ion Conveyor”: traveling waves guide ions in gas out of strong magnetic field G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Manipulation Beam Cooling and Bunching Low-energy low-emittance beams Key for precision experiments High resolution mass separation Conversion of continuous beams into bunched beams Increase sensitivity in experiments – example laser spectroscopy Efficient injection into traps and charge breeders Challenges Even lower emittance Higher beam rate capability G. Bollen, FRIB-China WS, 28 May 2015

Advanced Beam Cooler and Bunchers Several RFQ based beam cooler and bunchers already built at NSCL Penning trap mass spectrometry with LEBIT Laser spectroscopy with BECOLA Gas-filled ion guides after gas stoppers Advances Simplified electrode schemes to ease operation and increase reliability Cryogenic cooling to reduce emittance Designs optimized for higher beam rate capability New beam cooler and buncher to provide beams for ReA reaccelerator constructed Cryogenic cooling (50K) Optimized for fast cooling and bunching (<100ms) Optimized for high rate capability (107 ions per bunch  108 ions/s) 2013 2014 G. Bollen, FRIB-China WS, 28 May 2015

Rare Isotope Beam Manipulation Reacceleration Multi Harmonic Buncher 80 MHz RFQ 80 MHz SRF b=4.1% 80 MHz SRF b=8.5% > MeV/u beam Q/A Separator Mass separator N+ 1+ 1+ N+ Gas stopper Charge Breeder > 50 MeV/u Beams Reacceleration to provide high quality beams in energy range 0.2-20 MeV/u ISOL beams Beams from in-flight production or fission source after gas stopping High efficiency, high beam purity, and high beam rate capability needed Charge breeding in EBIT/EBIS and modern linear accelerators is state-of-art Significant development potential Higher beam rate capability Flexible time structure to meet experiment needs G. Bollen, FRIB-China WS, 28 May 2015

ReA design choices: EBIT charge breeder Achromatic Mass Separator Pilot source for linac tuning MHB 0.041 modules RT RFQ 0.085 module FY14 n+ RIB beam EBIT 1+ RIB beam EBIT: Short breeding time High ionization efficiency Charge state flexibility Low beam contamination 0.5 ≥ Q/A ≥ 0.2 G. Bollen, FRIB-China WS, 28 May 2015

ReA Design Choices: RT-RFQ With External Buncher And High Efficiency SC-Linac Pilot source Q/A MHB 0.041 modules RT RFQ 0.085 module FY14 n+ RIB beam EBIT 1+ RIB beam SRF LINAC 80.5 MHz RF frequency Flexible energy range (deceleration 300keV/u to maximum linac energy in small steps External multi harmonic buncher to minimize the longitudinal emittance Prebuncher studies to increase bunch separation G. Bollen, FRIB-China WS, 28 May 2015

Optimizing ReA Beam Time Structure Investigating Different Beam Scenario EBIT provides flexibility in time structure of extracted beams, ranging from release of very short to long pulses. Prebuncher studies to increase accelerator bunch separation to 62ns G. Bollen, FRIB-China WS, 28 May 2015

Making Best Use of Rare Isotopes Produced Many rare isotopes are produced but only one isotope delivered to single user Produce a rare isotope beam, for example 200W from a 238U primary beam At the same time up to 1000 other isotopes are produced that could be harvested and used for other experiments or applications in a commensal mode of operation 1st workshop on “Isotope Harvesting at FRIB”, Santa Fe, 2010 2nd workshop on “Isotope Harvesting at FRIB”, East Lansing, 2012 3rd workshop on “Isotope Harvesting at FRIB”, St Louis, 2014 FRIB has provisions for isotope harvesting incorporated in the design Harvesting from water being tested at NSCL G. Bollen, FRIB-China WS, 28 May 2015

Harvesting from FRIB Primary Beam Dump and Fragment Catchers Isotopes obtained in commensal mode of operation from cooling water loops Provisions in FRIB cooling loop design Fragment catcher cooling water can be separated from main beam dump loop Fragment harvester can be separated from main loop Provisions to bypass flow from main beam dump loop included Space for harvesting equipment reserved in FRIB target facility   238U 136Xe 86Kr 48Ca  Isotope Half Life Activity [mCi] 28Mg 0.87 d 7 36 190 2100 32Si 132 y 0.1 0.4 2 25 44Ti 60 y 0.8 5 0.9 48V 16 d 80 385 2200 67Cu 2.6 d 200 100 950 85Kr 10.8 y 50 1700 211Rn 14.6 h 230 221Rn 0.42 h 4 223Rn 0.39 h 1 225Rn 270 s 225Ac 10 d 170 Isotope inventories in beam dump cooling loop after 1 year of operation For shorter-lived (<<1 y) isotopes much larger activities harvestable Example: Isotopes for Fundamental Interaction studies harvested from beam dump (238U Beam): 225Ra: 6 x 109 /s; 223Rn: 8 x 107 /s; 208-220Fr: 109 -1010 /s G. Bollen, FRIB-China WS, 28 May 2015

Making Best Use of Beams Available Using Unused Beams - Commensal Operation Make use of off-axis rare isotope beams in focal planes Stopped and reaccelerated beams for experiments parallel to fast beam experiments Activities He-jet ion guide system (NSCL/ORNL/UNIRIB) successfully tested at ORNL with Cf source and ready to be shipped to NSCL Plan is to install catcher in A1900 focal plane Catcher Ion source systems in focal plane for fast extraction and delivery G. Bollen, FRIB-China WS, 28 May 2015

Commensal Use of Mass-separated Isotopes Spatial dispersion of different isotopes at focal planes Possibility to harvest off-axis isotopes FRIB example: primary experiment selects 82Ge from an 86Kr beam Other fragments mass-dispersed, available off-axis Can be intercepted by catchers and catcher-ion source systems 84Se 83Se 81As On-axis beam Rate 78Ge Simulation in LISE++ (O. Tarasov, D. Bazin) (http://groups.nscl.msu.edu/lise/lise.html) 82Ge Position G. Bollen, FRIB-China WS, 28 May 2015

Summary Facility developments are needed to advance science High-power is a very important ingredient and meeting its challenges will require continues development Leveraging higher production rates requires advances in beam manipulation to provide beams that meet experiments’ needs New instrumentation is needed that can cope with increased beam rates, satisfy demand for better time resolution Making best use of rare isotopes beams is mandatory – providing opportunities for multi-user operation, harvesting isotopes for societal needs Many challenges are common to many rare isotope beam facilities – provide opportunities for collaboration G. Bollen, FRIB-China WS, 28 May 2015