georg bollen michigan state university facility developments

Georg BollenMichigan State University

Facility Developments

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

Outline

G. Bollen, FRIB-China WS, 28 May 2015 , Slide 2

Rare Isotope Beams Facilities Based on AcceleratorsMany Challenges in Common


Rare Isotope Beam Production


MSIon source

Protons, 1 GeVneutrons, photons, …

ISOL production

High intensity, good beam quality, low energy Ready for “stopped beam “ experiments (traps, lasers)and reaccelerationNot all elements possible, decay losses

Beam StoppingThermalization

Fast beam fragmentation and in-flight separation

No chemistry involved, fast, universal productionHigh beam energy – high sensitivity (single-particle ID)Lower intensity, large beam emittance

MS

Target

Heavy ions, <2GeV/u >100 MeV/u

0.1 -20 MeV/u

60 keVRe-acceleration

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)

Challenges in Rare Isotope Beam Production


Example FRIB fast beam rates

• 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

Fast, Stopped, and Reaccelerated Beams for Broad Science Opportunities

, Slide 6G. Bollen, FRIB-China WS, 28 May 2015

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 ProductionFRIB Superconducting RF Driver Linac

, Slide 7

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


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

Accelerator Technical ChallengesExample: Charge Stripping of Intense Heavy Ion Beams

, Slide 8

Three-stage magnetic fragment separator• High acceptance, high resolution

to maximize science

High-power Rare Isotope Beam ProductionFRIB Fragment Separator


Multi-slice rotating graphite target

Water-filled rotating beam dump

New approaches and advanced techniques needed

Radiation resistant magnets


Production Target• 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

High-power Rare Isotope Beam Production High-power Production Target for FRIB

, Slide 10

Many common challenges in high-power targetry

Rare Isotope Beam ProductionAchieving 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

• 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

Rare Isotope Beam ManipulationMaximize 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

Rare Isotope Beam ManipulationMajor Topic at Recent EMIS Conference


International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) Grand Rapids, MI, May 11-15, 2015


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

Beam Stopping

, Slide 14

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

Beam StoppingSignificant Development Potential


Ion surfing using traveling waves provides fast ion transport in gas

“Ion Conveyor”: traveling waves guide ions in gas out of strong magnetic field

Beam StoppingAdvances in Low-Energy RF Ion Transport Techniques



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

Rare Isotope Beam ManipulationBeam Cooling and Bunching

, Slide 17

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)

Advanced Beam Cooler and Bunchers

2013

2014



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

Rare Isotope Beam ManipulationReacceleration

, Slide 19

Gas stopper

Massseparator

Q/ASeparator

Charge Breeder

> 50 MeV/uBeams

MultiHarmonicBuncher

80 MHzRFQ

80 MHzSRF

b=4.1%

80 MHzSRF

b=8.5%

N+ 1+

> MeV/u beam

1+N+

ReA design choices: EBIT charge breeder

0.085 moduleFY14

0.041 modulesRT RFQ

MHB

Achromatic Mass Separator

Pilot source for linac tuning

n+ RIB beam

EBIT1+ RIB beam

EBIT:• Short breeding time• High ionization efficiency• Charge state flexibility• Low beam contamination• 0.5 ≥ Q/A ≥ 0.2


0.085 moduleFY14

0.041 modulesRT RFQ

MHB

Q/A

Pilot source

ReA Design Choices: RT-RFQ With External Buncher And High Efficiency SC-Linac

n+ RIB beam

EBIT1+ 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


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

Optimizing ReA Beam Time StructureInvestigating Different Beam Scenario

0 1 2 3 4

0 1 2 3 4

0 1 2 3 4

Train

Conventional

Ramp

Time [ms]



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

Making Best Use of Rare Isotopes Produced

, Slide 23

FRIB has provisions for isotope harvesting incorporated in the design

Harvesting from water being tested at NSCL

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


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

Harvesting from FRIB Primary Beam Dump and Fragment Catchers

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 0.1 0.8 5 0.9

48V 16 d 80 385 2200 80

67Cu 2.6 d 200 100 950

85Kr 10.8 y 50 2 1700

211Rn 14.6 h 230

221Rn 0.42 h 4

223Rn 0.39 h 1

225Rn 270 s 2

225Ac 10 d 170

Isotope inventories in beam dump cooling loop after 1 year of operationFor shorter-lived (<<1 y) isotopes much larger activities harvestable

, Slide 24

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


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

Making Best Use of Beams AvailableUsing Unused Beams - Commensal Operation

, Slide 25


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

Commensal Use of Mass-separated Isotopes

82Ge

84Se83Se

81As

78Ge

On-

axis

bea

m

Rat

e

Simulation in LISE++ (O. Tarasov, D. Bazin)(http://groups.nscl.msu.edu/lise/lise.html)

Position

, Slide 26

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

Summary


Many challenges are common to many rare isotope beam facilities – provide opportunities for collaboration

georg bollen michigan state university facility developments

Documents

rare isotope beam productiong

mevuprovide beam power

fribchina ws

beam experiments traps

advanced beam manipulation

good beam quality

rare isotope beams facilities

rare isotopes