1. Facility Developments
Georg Bollen Michigan State University

2. 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

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

4. Rare Isotope Beam Production
ISOL production
Protons, 1 GeV
neutrons, photons, … MS
Target
Heavy ions, <2GeV/u
>100 MeV/u
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

5. 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

6. 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 ( 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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+ N+
Gas
stopper
Charge
Breeder
> 50 MeV/u
Beams
Reacceleration to provide high quality beams in energy range 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

20. 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

21. 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

22. 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

23. 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

24. 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; Fr: /s
G. Bollen, FRIB-China WS, 28 May 2015

25. 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

26. 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) (
82Ge
Position
G. Bollen, FRIB-China WS, 28 May 2015

27. 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