Beam Commissioning and Isotope Purification
for FRIB User Experiments
Speaker: Kei Fukushima
Marc Hausmann, Kyung Hwang, Tomofumi Maruta, Peter Ostroumov, Alexander Plastun, Mauricio
Portillo, Bradley M. Sherrill, Mathias Steiner, Oleg Tarasov, Tong Zhang, Qiang Zhao
Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 USAThis material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of
the Facility for Rare Isotope Beams (FRIB) Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633.

Outline Introduction• FRIB Linac, Fragment Separator (ARIS), Experimental beamlines

 Status of FRIB since operation starts• Recent upgrades, multi-charge-state operation

 ARIS configuration and operation• Beam commissioning of ARIS for user operation• Experimental beamline tuning for user stations• Complexity of ARIS and Challenges

 Summary

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 2

Facility for Rare Isotope Beams @MSU

- Exploring new, unexplored regions of the nuclear chart Designed to accelerate all stable ions above 200 MeV/u with 400 kW• FRIB Construction Completed in Jan. 2022 On Cost and Five Months ahead of Schedule• FRIB is now a DOE-SC scientific user facility for rare isotope research supporting the mission of the
Office of Nuclear Physics in DOE-SC

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 3

Facility for Rare Isotope Beams @MSU

- Exploring new, unexplored regions of the nuclear chart Designed to accelerate all stable ions above 200 MeV/u with 400 kW• FRIB Construction Completed in Jan. 2022 On Cost and Five Months ahead of Schedule• FRIB is now a DOE-SC scientific user facility for rare isotope research supporting the mission of the
Office of Nuclear Physics in DOE-SC
Rare Isotope Beam Rates in FRIB
238U

Predicted at 10 kW

2 May 2022

78,86Kr

Presently
known

36Ar

82Se
48Ca

FRIB ribbon cutting ceremony
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

Log Rate /s

124Xe

Fast beam rates > 1/day 

16,18O

O. Tarasov
K. Fukushima, PASJ2023, Slide 4

FRIB Outline: Linac
 Linac, target, and dump are located 10m underground• 3 super-conducting linac segments (LS1~3)• Charge stripper is located after LS1» Liquid Lithium stripper and Rotating carbon stripper

Production Target
Charge Stripper

Beam comes from the ground floor ECR
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 5

FRIB Outline: Fragment Separator
 Advanced Rare Isotope Separator (ARIS)• In-flight separation of projectile fragments• Transport rare isotope (RI) beam to ground level in vertical pre-separator• Separation performed by both PS and C-bend• Identify the RI beam for users

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 6

FRIB Outline: Experimental Beamline
 Serves science with the unique availability of fast, stopped,
re-accelerated beams

N4 line to gas stopper(connect to Re-Accelerator)

RI beam from
ARIS C-bend

FDSi

S800 line to GRETINA station(Gamma-Ray Energy Tracking In-beam Nuclear Array)(FRIB beta-Decay Station initiator)

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 7

Current Status of FRIB FRIB has steadily ramped up beam power to 5 kW
 More than 250 unstable isotope beams have been delivered to FRIB experiments
Date

Objective

Destination

Primary beam

EnergyPower

May 2022

User experiment 21062

FDSi

48Ca

173 MeV/u

1 kW

Jun 2022

User experiment 21069

FDSi

82Se

165 MeV/u

1 kW

Aug 2022

User experiment 21007

S800

70Zn

173 MeV/u

1 kW

Nov 2022

User experiment 21072

FDSi

36Ar

210 MeV/u

3 kW

Dec 2022

User experiment 21003

S800

124Xe

227 MeV/u

3 kW

Dec 2022

User experiment 22601

N4

36Ar

210 MeV/u

3 kW

Jan 2023

User experiment 23602

N4

124Xe

227 MeV/u

3 kW

186 MeV/u

3 kW

Feb 2023

User experiment 22501

ARIS

198Pt

Feb 2023

User experiment 21049

N4

124Xe

227 MeV/u

5 kW

Mar 2023

User experiment 23603

N4

36Ar

210 MeV/u

5 kW

Mar 2023

User experiment 21009

S800

48Ca

197 MeV/u

5 kW

Apr 2023

User experiment 21034

S800

124Xe

227 MeV/u

5 kW

May 2023

User experiment 23605

N4

40Ar

200 MeV/u

5 kW

Jun 2023

User experiment 21014

S800

64Zn

240 MeV/u

5 kW

Jul 2023

User experiment 21009A

S800

48Ca

197 MeV/u

5 kW

Jul 2023

User experiment 21001A

S800

48Ca

217 MeV/u

5 kW

 Performed 8 primary beams,
up to 240 MeV/u Can be delivered if scheduled
Primary beam
36Ar
40Ar

48Ca
70Zn
64Zn
78Kr
86Kr

82Se

124Xe
198Pt

208Pb
209Bi

Max energy[MeV/u]
290
262
242
241
254
254
230
227
228
188
184
186
K. Fukushima, PASJ2023 , Slide 8

Upgrades for Power Ramp Up after the First Experiments in 2022
 Support 5 kW and more power operation:• Static drum target replaced with the rotating Carbon target• Flat beam dump replaced with the S-shape beam dump

 Improve the performance of isotope separation and rate

• 2 quadrupole doublets in pre-separator replaced with larger aperture triple• Install 3 corrector (steering) magnets in pre-separator

 All installed
Rotation Target

S-Shape Beam Dump

New Triplet (CIQT4)New Corrector

6°
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 9Adopted Multi-Charge-State Acceleration as Normal Operation
 Pros• Delivery of x2~x3 higher power heavy ion beams to the target compared to single charge state» 124Xe stripping efficiency is 33% into 50+ and 77% into 49+,50+,51+» Extremely beneficial if the ion source has intensity limitation e.g., 198Pt beam

• Reduction of power deposition on the charge selection slits downstream of the stripper» Less activation of cooling water and air» Less prompt radiation and induced radio activation

 Cons• Beam tuning takes more time (~42 hours for new beam)» Align the transverse position of the center charge state (e.g. 124Xe50+) in each quadrupole in the bend section» Tune neighbor charge state (e.g. 124Xe49+, 124Xe51+) to the same transverse position after the bend section» Tune sextupoels in the bend section to minimize the position offset in 6D phase space» Measure Twiss parameters for each charge state in each section» Find the optimum quadrupole setting to match transversely by using an envelope simulation

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 10

Adopted Multi-Charge-State Acceleration as Normal Operation
 Accelerated multi-charge-state beams after the stripper• 124Xe: 49+, 50+, 51+ (3q, operation)• 198Pt: 66+, 67+, 68+ (3q, operation)• 64Zn: 28+, 29+ (2q, operation)• 48Ca: 19+, 20+ (2q, demonstration)

124Xe-3q Beam image ontarget disc w/o rotation,
RMS size x,y = 0.3, 0.3 [mm]124Xe-3q beam envelope in final focusing system

3σ ellipse(phase space measured by profile monitor)

Production
target disc
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

6σ ellipse

K. Fukushima, PASJ2023, Slide 11

Demonstrated 10 kW Beam Before Shutdown This Summer Send 10 kW - 48Ca and 36Ar beam to the 8 mm Carbon target and S-shape beam dump,
measured peak temperature by the thermal camera No major issue found, and 10 kW operation will start within a year
Beam power history and the temperatures of the collimator
upstream of the target disc

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

Thermal image of the target disc

K. Fukushima, PASJ2023, Slide 12

Isotope Purification in ARIS
 Up to 3-stage in-flight fragment separation
 Atom-by-atom identification of A, Z, q
Example: 78Ni from 86Kr
86Kr

Fragments
after target

Fragments
after wedge slit

Fragments
after focal point slit

K. Fukushima, PASJ2023, Slide 13

Beam Optics Design of ARIS Multi-stage separation• Pre-separator applies 3x momentum compression by wedge material• C-bend can operate as one or two achromatic focusing for more separation• Beam Optics Designed by COSY infinity (X: dispersive, Y: non-dispersive plane)Pre-separator

C-BendK. Fukushima, PASJ2023, Slide 14

Magnet Mapping Completed Offline
 ARIS magnets contain Quad, Sext, and Octupole, and inducible independently
 Mapping completed for all higher multipole fields offline (most magnets are superconducting) Mapping results are fit by Enge function including the induced current and used in beam dynamics codefor optics calculation
Mapper: hall sensor every
5 degree about a ring

Quadrupole triplet in PS

Effective length for each quadwith the same design
Tesla

Z (mm)

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 15

Viewer and PPACs Installed and Calibrated• Viola (Online Viewer App.) Installed viewer plate and PPAC (Parallel Plate Avalanche Counter) Viewer plate• Raw camera image• Pros» Fast measurement ~0.5 sec» Large enough compared to the beam

• Cons» Required beam power ~0.2 W

 PPAC• Pros» Trackable particle event by event» Phase space measurement by two PPACs» Measurable a very low-intensity beam

Reshape by affine
transformation,
calculate statistics (centroid, RMS, etc.)
in ~0.3 sec for 2K resolution image• PPACs result at DB5 (64Fe)
X-X’ phase space

Y-Y’ phase space• Cons» Slow measurement ~5min» Maximum rate is limited by trigger system ~2000 pps
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 16

Particle Identification (PID) Performed in ARIS
 Particle identification (PID) performed by measurements of energy loss, total kinetic
energy, and time-of-flight>> Identify and calculate particle rates of the RI beam for user
All isotopes

86Kr35+

Kr (Z=36)
Br (Z=35)
Se (Z=34)

84Se

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

Only isotopes in fully
stripped charge state

84Se34+

K. Fukushima, PASJ2023, Slide 17

Transverse Matching Performed to Improve the Separation
 Quadrupole optimization for Twiss parameter matching
1. Measure the phase space at the matching point• Beam envelope simulation result

Backward simulation» PPACs measure the beam phase space directly» Quadrupole scan provides the beam phase space also

2. Simulate backward to 3~4 upstream quadrupoles
3. Optimize quadrupoles by using simulation

DB1
PPACs

» 4-knobs optimization takes ~1 sec by using FLAME[1] simulation

4. Apply optimized quadrupole settings to the real machine

Quads for optimization>> The entire procedure takes ~10 minutes.
• 64Fe phase space at DB1 PPACs before matching

X-X’

Y-Y’

[1] FLAME (https://frib-high-level-controls.github.io/flame-utils/)• Phase space after matching

X-X’

Y-Y’

K. Fukushima, PASJ2023, Slide 18

Beam-Based Alignments Performed by Q-offsetting Method
 Quadrupole offsetting method

1. Inject parallel beam from linac and turn off all quadrupoles, sextupoles, and octupoles in ARIS
2. Turn on a quadrupole one by one and check the centroid shift at the downstream viewer
3. The amount of the centroid shift gives the beam centroid offset against the magnetic center
4. Simulate the beam trajectory to reproduce the kick from the quadrupoles
5. Difference between the trajectory and the centroid offset shows the misalignment of the quadrupoles• Vertical trajectory in pre-separator+0.255%+0.280%• Horizontal trajectory in pre-separator-0.058 %-0.064 %• Horizontal misalignment of quadrupoles• Vertical misalignment of quadrupoles
Vertical bends

Target

Wedge

DB0

DB1

TargetWedge

DB0
K. Fukushima, PASJ2023, Slide 19

DB1

Experimental Beamline
 Serves science with the unique availability of fast, stopped,
re-accelerated beams

N4 line to gas stopper(connect to Re-Accelerator)

RI beam from
ARIS C-bend

FDSi

S800 line to GRETINA station(Gamma-Ray Energy Tracking In-beam Nuclear Array)(FRIB beta-Decay Station initiator)

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 20

Beam Tuning in Experimental Beamlines
 The fragments sent from ARIS differ in each experiment due to the different slit settings etc.
 Transverse matching at DB5 transports the beam to the user station with the highest efficiency
 Mostly, more exotic fragments setting from ARIS have larger emittance to maximize the total
rate by sacrificing the purity
28P (2.3e6 pps @ 5kW)

Geom. RMS Emittance X, Y = 33.2, 44.8 [mm-mrad]

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

42Si (12 pps @ 5kW)

Geom. RMS Emittance X, Y = 60.5, 83.3 [mm-mrad]

K. Fukushima, PASJ2023, Slide 21

Envelope Simulation and Beam Size Measurements
 Verified beam sizes at each viewer plate, and it is consistent with the simulation result
 Simulated transmission is consistent with the measurements also

• Centroid trajectory is corrected by viewers, but the tuning knobs (steering magnets) is not enough Conclusion: Performed optimum beamline setting for users
29Mg beam envelope DB5 to S800

Calculated transmission 74% (82% in exp.)

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

29Mg beam envelope: DB5 to N4 gas stopper

Calculated transmission 64% (50% in exp.)

K. Fukushima, PASJ2023, Slide 22Complexity of ARIS and Challenges
 Experimental beamlines consist of legacy magnets, and the apertures are small User request the maximum rate at their detector even in worse purity• In current beam power (~5 kW), we can only open slits to increase the rate of fragments» The beam emittance from ARIS gets larger than the initial estimation» Once the power is ramped up, ARIS serves more separation by narrower slits, and squeezes the emittance Unique mixed vertical and horizontal separation with momentum compression• Performance of the momentum compression depends on the wedge quality» Dispersion must be matched to the effective wedge angle and thickness• Momentum compression converts longitudinal emittance to transverse emittance in dispersive plane» Legacy experimental beamlines did not designed for the large vertical emittance High order correction with 33 sextupoles and 27 octupoles• All superconducting, ramping time is slow
• Sextupole excite dipole component also, could be compensate by additional corrector magnets• Tuning requires more time, but currently the user operation schedule is prioritized
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 23

Summary FRIB conducted 16 experiments, delivered ~250 unstable isotope beams in the first year
 Linac performed up to 5 kW, 240 MeV/u with various primary beam
 The performance of ARIS has been successful in user experiments, but areas for improvements exist
 Demonstrated 10 kW beam to the rotating Carbon target and S-shape beam dump
 Performing phased development of target/dump system
Phase

~1 kW

~10 kW~20 kW~50 kW

to 400 kW

Production
TargetStatic Mult-Position

Single-Slice
Rotating

Single-Slice
Rotating

Single to MultiSlice Rotating

Multi-Slice Rotating

Beam Dump

20 deg. Static(Flat shape)

6 deg. Static(S-shape)

6 deg. Static(S-shape, better cooling)

Rotatable beam dump,
1 mm wall

Rotatable beam dump,
0.5 mm wall

Completed!

WE AREHERE!

 (Upgrade to 400 MeV/u, R&D in progress)
Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 24

Ongoing Accelerator Projects in the U.S.
Lots of opportunities are available in the accelerator field in the U.S.
 Facility for Rare Isotope Beams (FRIB) @ MSU• $730 million (completed) + $529 million for next 5 years operation

 Electron-Ion Collider (EIC) @ BNL• $1.7 ~ $2.8 billion, aiming to complete in 2031

 Spallation Neutron Source (SNS) - Second Target Station @ ORNL
• $1.8 ~ $3 billion , aiming to complete in 2037

 Proton Improvement Plan-II (PIP-II) @ FNAL
• $978 million, aiming to complete in 2033

 Linac Coherent Light Source II High Energy (LCLS-II-HE) @ SLAC
• $290 ~ $660 million, aiming to complete in 2030

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 25

Acknowledgements
 This material is based upon work supported by the U.S. Department of Energy, Office of
Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams(FRIB) Operations, which is a DOE Office of Science User Facility under Award Number DESC0023633.

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 26

 Backup.

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 27

Beam Development for User Experiments
 Once the experiment proposal is approved:• Optimize and install primary beam energy, target disc thickness, and wedge thickness

 Primary beam development (PDT)• Development of new primary beam setting takes ~42 hours• Restoring of primary beam setting takes ~24 hours• Target Disk Changes by Remote Handling Secondary beam development (SDT)• Measure the effective thickness of each material• Optimize the detector setting for lighter or heavier ions
• Perform particle identification by ARIS detectors• Maximize the rate of the fragment of interest (FOI)» Rigidity scan: find FOI energy center by scanning the dipole field» Transverse matching: optimize the phase space at the slit

• Total ~1 week including communication with users

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 28

Future Mitigation Approach of Stripper Effects on Beam
 Measured liquid Li stripper thickness distribution shows
the thickness and uniformity have a trade-off• Thicker LLi provides more stripping efficiency• Non-uniformity causes more energy spread

Collimator

Li stripper• Beam optics and dispersion with 124Xe50+

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

Charge selector

 SRIM simulation with the measured thickness distributionagreed with the measured energy spread by using special
opticsK. Fukushima, PASJ2023, Slide 29

Future Mitigation Approach of Stripper Effects on Beam
 Measured liquid Li stripper thickness distribution shows
the thickness and uniformity have a trade-off• Thicker LLi provides more stripping efficiency• Non-uniformity causes more energy spread

Collimator

Li stripper• Beam optics and dispersion with 124Xe50+

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu• Energy spread after LLi

Charge selector

 SRIM simulation with the measured thickness distributionagreed with the measured energy spread by using special
opticsK. Fukushima, PASJ2023, Slide 30

Optics Base Solution: Reduce the Beam Size on Stripper
 Reduce beam size on LLi stripper to minimize beam energy variation after the stripper• Requires replacement of the quadrupoles in upstream and downstream of the stripper• RMS beam size on the stripper could be from 0.5 mm to 0.25 mm

Facility for Rare Isotope Beams
U.S. Department of Energy Office of Science | Michigan State University
640 South Shaw Lane • East Lansing, MI 48824, USA
frib.msu.edu

K. Fukushima, PASJ2023, Slide 31