APPLICATIONS OF LOW ENERGY HADRON BEAMS

Eric Prebys

Professor, Physics Department, UC Davis

Director, Crocker Nuclear Laboratory

NATCAT Lecture

Outline

• Motivation
• General techniques
• Some representative facilities
• A few words about Crocker Nuclear Lab

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Scope of this talk

• “Low Energy Hadron Beams”
• <~1000 MeV/u
• Includes FRIB (MSU)
• Doesn’t include
• RHIC (BNL)
• SNS (Oak Ridge)
• Reactor facilities
• Will include applications in
• Nuclear physics
• Medical physics
• Isotope production
• Education
• Material Science/Industrial Applications
• Will not include
• Muons
• Neutrinos

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

A Particle Physicist Looks at Nuclear Physics

• Caveat: my background is in particle physics and accelerator physics, so I tend to view nuclear physics in terms of facilities and their capabilities
• Broadly speaking, low energy nuclear physics falls into the following categories
• Precision p,n,d,α cross-section measurements
• Astrophysics and the search for new elements
• Interactions of heavier nucleii, studied with
• Stable primary ion beams
• Unstable secondary ion beams
• Activation/dosimetry studies
• Isotope production
• p, d, and α beams

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Of particular interest in nuclear security

Context

• In 2015, the DOE commissioned a report “Reaching for the Horizon: The Long Range Plans for Nuclear Science”
• This identifies the following “Big Questions”
1. How did visible matter come into being and how does it evolve?
2. How does subatomic matter organize itself and what phenomena emerge?
3. Are the fundamental interactions that are basic to the structure of matter fully understood?
4. How can the knowledge and technical progress provided by nuclear physics best be used to benefit society?
• Low energy facilities – even very old ones – can contribute in all of these areas.
• Can also include education and instrumentation development

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Relevant to NSSC

Relevant to HEPCAT

Non-Nuclear Physics Applications

• Ionizing energy deposition
• Cancer treatment
• Radiation damage/single event upset
• For practical reasons, this is often combined with activation studies
• Analysis
• Proton Induced X-Ray Emission (PIXE)
• Proton scattering
• Proton and neutron radiography
• Instrumentation Development
• Low energy beams are a test bed for novel instrumentation
• Educational opportunities across all areas.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Need for Nuclear Cross Section Measurements

• In spite of the fact that nuclear physics has been around for a long time, there is still a need for precision low energy measurements. Applications include
• Stockpile stewardship
• Do aging weapons remain viable?
• Verification
• Interrogation
• Nuclear forensics
• Accelerator-driven subcritical systems
• Astrophysics
• Activation/damage studies
• Particular interest in n,γ time and angular correlations
• Modern instrumentation allows things that weren’t possible when early measurements were made.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Background for Nuclear Data Needs

• In 2015, the “Workshop on Nuclear Data Needs and Capabilities for Applications” was held at LBNL
• Details found at http://bang.berkeley.edu/events/ndnca/*
• Good summary of needs for nuclear data
• Mostly precision n, p, and α reactions
• Nice overview of facilities
• Linear accelerators
• Cyclotrons
• Van de Graaffs
• Reactors
• There have been some subsequent workshops and papers, but this still the most thorough.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

*This is a fantastic resource!

Accelerator-Driven Subcritical Systems (ADS)

• Traditional nuclear reactors use (moderately) enriched Uranium (²³⁵U) assembled to create a self-sustaining critical nuclear reaction.
• ADS systems involve assembling subcritical amounts of ²³⁸U, and then exposing them to an intense proton beam to generate power through the reaction

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• Can also work with the reaction

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• This is extremely interesting to India (where there are immense Thorium reserves)
• Very challenging. Requires:
• Very reliable, high power particle accelerators
• Very precise knowledge of nuclear reactions

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E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Chain reaction

Chain reaction

Pros and cons of ADS Systems

• Pros:
• Does not require enriched feedstock (no proliferation worries)!
• Safe: turn off proton beam, reactor goes off. No meltdowns
• Burns up long-lived actinides -> ~<100 year half-lives instead of 10,000 year half-lives
• You can also just do this part (“transmutation”)
• Cons:
• Nuclear reactions complicated. Similar to breeder reactors, which haven’t been a rousing success.
• This is where precision cross-sections come in!
• Adding a very expensive and complicated thing (high power accelerator) to an already expensive and complicated thing.
• Very challenging. Requires:
• Very reliable, high power particle accelerators
• Very precise knowledge of nuclear reactions

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E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Cross Section Examples

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Pages and pages like this. Mostly limited by the number of people doing the measurements, rather than the capabilities of particular facilities

Astrophysical Processes*

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

*source: “FRIB: Opening new Frontiers in Science

“We are Star Stuff

We are golden

We are billion-year-old carbon”

- (Crosby, Stills, and Nash version of) Joni Mitchel’s “Woodstock”

Poetic license on age

Nuclear Physics Inside Supernovae

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

What’s happening in here?

Hadron Beams for Radiation Damage and Single Event Upset Studies

• Proton and heavy ion beams are used as a source of ionizing radiation, to determine
• Damage and single event upset thresholds for electronics
• Radiation hardness of other fabrication materials
• Applications:
• Devices going into space
• Devices being used in high radiation environments like reactors and HEP experiments
• Extreme reliability of high-density electronics on
• How likely is it that a cosmic ray will cause a logical error?

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Figure of Merit: Linear Energy Transfer (LET)

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Source: Texas A&M Cyclotron Institute

Using Proton Beams for Material Analysis*

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

*courtesy Prof. Tom Cahill

PIXE Spectrum

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Example: Guttenberg Bible

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Isotope Production in Hadron Beams

• The biggest needs for isotopes fall into two categories
• β⁺ emitters, used for PET

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• β⁻ and α emitters, used for treatment

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Some Isotope Production Facilities

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Requires α beams!

²¹¹At

• ²¹¹At is an α-emitter in which there is a lot of interest for cancer treatment. Problems
• Produced in the reaction

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While most isotope production cyclotrons produce p and d at lower energies.

• 7.2 hour half-life
• Crocker Nuclear Lab recently demonstrated the production and recovery of ²¹¹At, making it the only potential source in California.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Sources of Low Energy Hadron Beams

• Van de Graaf Accelerators
• Up to few energy MeV protons
• Cyclotrons
• Up to ~1 GeV protons
• Linear Accelerators
• Up to ~1 GeV protons
• For higher energy, use “synchrotrons”, in which the magnetic fields scale with beam momentum to keep particles in the same orbit
• Example: Large Hadron Collider (LHC), 7 TeV protons

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Tandem Van de Graaff Accelerators

• Exploit static electric fields

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• Energy up to a few MeV/u

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Cyclotrons

• An alternating electric field is used to drive charged particles in a fixed magnetic field

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Linear Accelerators

• Linear accelerators use sequential RF cavities with alternating fields to accelerate particles

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Production of Ions

• Older sources:
• A hot filament + an arc produces a plasma, and ions are extracted electrostatically
• Works for p, d, T, ³He, and α
• Special case: H^-
• Heated H is mixed with Cesium vapor
• Heavier ions are produced in ECR sources…

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Electron Cyclotron Resonance (ECR) Ion Sources

• Gas or vapor is introduced into a solenoidal magnetic field, which is driven by microwaves at the Electron Cyclotron Resonance resulting in ionization of the atoms.

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• Can select virtually any �ion for acceleration

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Texas A&M ECR gas switchyard

Production of Neutrons for physics and therapy

• Most low energy facilities use deuteron beams and produce neutrons through the reaction

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• The Fermilab neutron therapy produced spallation neutrons by bombarding a Beryllium target with 66 MeV protons
• The Spallation Neutron Source (SNS) produces spallation neutrons by bombarding a Mercury target with ~1 GeV protons
• Liquid Mercury used for cooling reasons

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

National Superconducting Cyclotron Laboratory (MSU)

• K500 and K1200 superconducting cyclotrons
• Accelerates protons through heavy ions
• K500 can produce unstable isotopes, which are then reaccelerated in K1200 for research

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Facility for Rare Isotope Beams (FRIB)

• Also at NSCRL
• The next “big thing” in nuclear physics
• Will use a versatile linear accelerator to produce unstable secondary beams, which are then studied and/or reaccelerated
• Recently began operation, on budget and ahead of schedule!

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

-MSU Today,

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Berkeley 88” Cyclotron

• Built in the 1960s
• Accelerates protons up to 55 MeV, and heavy ions through Uranium
• Used for nuclear physics and radiation effects

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Berkeley 88” Heavy Nuclei Production

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

This is where they pencil in new elements

Precision spectrometer

Source Development

• The 88” has also served as a test bed for ECR ion source development

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Texas A&M Cyclotron Institute

• Began in the 1960s
• K150 is identical to the Berkeley 88”
• K500 is a superconducting cyclotron similar to the NCSRL K500, but it worked first (1980)
• Currently used for nuclear science and radiation effects

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

MARS Facility (Texas A&M)

• Generate and kinematically separate unstable nuclei

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Los Alamos Neutron Science Center (LANSCE)

• The LANSCE facility is driven by an extremely versatile proton linac with
• Variable energies up to 800 MeV
• Average currents up to 1 mA
• Pulsed, so peak current much higher

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

LANSCE Facility Overview*

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

*talk by Lawrence Rybarcyk, 2008

Digression: The Berkeley 60” Cyclotron⁺

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• A few of the people in this picture:
• (a) Ernest Lawrence*, inventor of the cyclotron, pioneer� in particle-based cancer therapy.
• (b) Louis Alvarez*, inventor of the linear accelerator� figured out (with his son) why dinosaurs died
• (c) Edwin McMillan*, inventor of the synchrotron, � discovered Plutonium with Glenn Seaborg
• (d) J. Robert Oppenheimer, father of the A-bomb
• (e) Robert Wilson, founder and first director of Fermilab

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

a

b

c

d

e

• Up to19 Mev Deuterons
• Discovered Plutonium and other transuranic elements
• Prototype for many across the country

⁺Crocker Radiation Lab

*Nobel laureate

The Cyclotron at UC Davis

• In the mid-1960s, the magnetic yoke and pole pieces were moved from Berkeley to UC Davis, and significantly upgraded
• Converted to “isochronous” – field falls of with radius to keep period constant
• Energy increased to 67 MeV �for protons
• Can also accelerate Deuterons �and Alpha Particles
• The cyclotron was an important step�in establishing the Davis physics program
• Did significant work in environmental �studies
• Some interesting things:
• CNL did much of the air sample testing that �established high concentrations of lead in �the atmosphere, leading to catalytic �converters �and unleaded gas
• CNL has studied the ink composition on �numerous historical documents, including a Gutenberg Bible, a Bible owned by J.S. Bach and the controversial “Vinland Map”
• Since the mid-1990s, the cyclotron has primarily been used for
• The treatment of uveal cancer, a form of cancer which forms behind the retina
• Studying radiation effects, mostly for the aerospace industry.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Cyclotron Layout

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Cyclotron

Charged beam experimental lines. including PIXE line

Radiation Effects Area (line 2). Most used line.

Eye Therapy Facility

Experimental Counting Area or Secondary Neutron Line

High Radiation and Nuclear Cross Section Measurement Line

“Bread and Butter” Activities

• We continue to treat patients with uveal �cancer in the Eye Therapy Facility (ETF), �run by UCSF
• Course of treatment is four days in a row
• We treat between 3 and 16 patients M->Th, �one week per month
• Exposure is only one minute, but about a half�hour per patient with end effects.
• The rest of the time, we provide beams �radiation effects, primarily �for the aerospace industry. �Clients include
• NASA
• Airforce/Spaceforce
• JPL
• Google
• Apple
• AMD/Xilinx
• Numerous Bay Area companies

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

In Progress: Major Control Upgrade

• The control system of the cyclotron is original, from the 1960s
• Settings are made by adjusting analog controls, based on hand-written configuration sheets.

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• Our new electrical engineer Claudio Lopez is well along in the process of automating both the monitoring and the control of the cyclotron.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Control Upgrade (cont’d)

• The new system has a LabView layer and a Python Interface
• Data are logged to an SQLite database
• Configuration can be done using touch �screens.

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• Readout complete and operational!
• Control system will be complete withing a few months.
• Goals
• Improved performance through implementation of AI
• Simplified operation, allowing student operators to expand hours.
• Currently in discussion with SLAC to collaborate and seek funding

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E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Student Research at CNL

• We are currently supporting four graduate students and one undergrad to work on cyclotron-related projects
• Two grad students will finish in the next year.
• Logan Knudson will complete his PhD studying beam motion with a novel probe.
• Lena Korkeila will complete her PhD on nuclear cross-section measurements with the cyclotron as well as the production of ²¹¹At.
• These will be the first PhD theses out of the cyclotron in as long as anyone can remember!
• Two more grad students are just starting out
• Gabe Soto will do research related to the machine learning operation of the cyclotron
• Shucheng ”Andrew” Pai will do research on developing accurate models of beam motion.
• Also support an undergraduate, Evelyn Hamera, who is working with Lena
• Started as an REU from a Community College last summer before transferring to UCD this year.
• In that project, she designed and built an ionization chamber from scratch.

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Beam Probe

• Measurements made using gafchromic film have �shown that the beam in the cyclotron is larger than �we expect.
• Because there is currently no instrumentation, we can’t tell if this is due to oscillations.
• We have developed unique probe to study the motion �of the beam in the cyclotron, which is challenging �because of the harsh radiation environment and high �electrical noise.
• Recently successfully tested externally

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Nuclear Cross Section Measurements

• Believe it or not, there are still cross-sections of interest that can be measured with our cyclotron
• Of use for stockpile stewardship, reactor design, astrophysics, etc
• Limited by the number of people doing the measurements rather than the capabilities of the facility.
• We have demonstrated the measurement of
• Of interest for cancer treatment

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E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

²¹¹At Production

• One of the early successes of the lab was a grant from the DOE to develop the production of ²¹¹At, an isotope with the potential to treat cancer.
• Produced with an alpha beam on bismuth, so currently no commercial sources and no Bay area sources
• We demonstrated production in 2022, using an internal target developed for the purpose

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

²¹¹At Production (cont’d)

• Work was delayed for a variety of reasons.
• We have recently gotten a lot of queries from Bay Area researchers, so we are planning to reestablish production, using a simpler improved recovery technique developed at the Texas A&M Cyclotron.
• Already have researchers and UCSF interested in submitting a joint research proposal once we establish production.
• Stay tuned!

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023

Plans and Priorities in the Next Year

• Complete the spares for the two single-point failure elements.
• Complete the controls upgrade and begin work on AI control
• Hopefully bring in some grant money for this.
• Also looking at modernizing RF control with an ECE Master’s student.
• Continue cross section measurements in collaboration with UCB.
• Install beam probe, take and analyze data with it.
• Restart ²¹¹At production using the Texas A&M recovery technique.
• No source in bay area! (closest iUniversity of Washington)
• Recent uptick in local interest
• Already plans for a joint proposal with UCSF radiochemists
• Continue to pursue collaborations related to medical physics with Cherry Lab, UCSF, etc
• Pursue a collaboration with U of Alaska to high altitude air samples using drones, which can be analyzed using our PIXE line
• Of great interest to climate scientists!
• Always looking for new opportunities!

E. Prebys - Applications of Low Energy Hadron Accelerators

NATCAT School - June 10-11, 2023