What is the Spallation Neutron 

Source (SNS) at Oak Ridge National 

Laboratory (ORNL)? 

ORNL hosts two of the world’s most powerful 

sources of neutrons for research that help us 

better understand materials that affect our 

daily lives: the SNS and the High Flux Isotope 

Reactor (HFIR), which produce beams of 

neutrons by two different processes. 

The SNS is an accelerator-based facility 

with the world’s most powerful spallation 

source, providing intense neutron beams 

for scientific research and industrial 

development.

SNS delivers short pulses of protons—60 

times a second—to a target system where 

neutrons are produced through a process 

called spallation. 

Why neutrons?

Because neutrons have no electrical charge, they can easily pass through 

a sample of material without harming it, revealing information about the 

material’s structure and properties. 

Spallation Neutron Source

Accelerating science
How are neutrons made and 

collected at the SNS? 

The facility has equipment that 

provides a negatively charged 

hydrogen ion (a hydrogen 

atom with 2 electrons).

This tiny bunch of ions is sent 

down an accelerator (often 

referred to as the linac – short 

for linear accelerator).

The linac is quite large 

– approximately 3 

football fields long.

The accelerator has magnets to 

keep the ion beam in place and 

the accelerator uses electricity to 

move the beam along.

The linac is fast. The beam 

reaches nearly 90% the speed of 

light by the time it approaches 

the end of the linac.

The ions pass through a diamond 

foil that removes the electrons 

and produces protons, and the 

protons then enter what’s called 

an “accumulator ring.”

The protons circulate around the 

ring. More protons are added as 

they come off the linac.

Once the protons leave 

the ring, they smash into a 

liquid mercury target, and 

“spallate” or create 20 to 30 

neutrons for each interaction.

Next, the neutrons travel 

down tubes, or beamlines, 

until they reach the neutron 

scattering instruments.

But here’s the really cool 

part: The impact of neutrons 

on a sample material causes 

them to scatter at different 

angles–try to picture pool 

balls colliding–as the 

neutrons interact with atoms 

or magnetic fields in the 

sample materials. 

Special detectors around the sample 

materials measure these patterns and send 

this data to a computer.

The patterns reveal insights into a material’s 

internal structure at the atomic level.

ION SOURCE LINEAR ACCELERATOR

ACCUMULATOR RING

TARGET

NEUTRON 

SCATTERING INSTRUMENTS

FUTURE 

SECOND TARGET STATION

SAMPLE

DETECTOR

CENTRAL LABORATORY 

AND OFFICE COMPLEX
Neutron research

Neutron scattering is used to make 

new scientific discoveries and 

to provide a more fundamental 

understanding of materials. It’s 

used in many applied areas of 

research, including industry—

automotive, aerospace, steel, 

defense, industrial materials, 

energy storage, data storage, and 

biomedicine—to address many of 

the major scientific challenges of 

the 21st century.

Neutron research helps 

improve: 

• batteries and electronic devices

• alternative energy sources, such 

as solar cells

• transportation materials such as 

bridge cables, engine parts

• drugs and biologics

• biofuels

• polymers

• computing technologies

• airport security systems 

and more

User program

Each year the User Office issues two calls for research 

proposals. Submissions are peer-reviewed by external panels, 

with recommendations based on scientific and technological 

impact. Experiments are also reviewed for feasibility and 

safety, and the experience of the research team. Those with 

the highest potential for scientific impact are approved and 

scheduled for instrument access. 

Managed by UT-Battelle LLC for the US Department of Energy

One Bethel Valley Road

Oak Ridge, TN 37830

Office: 865-574-0058

neutrons.ornl.gov

The future: The Proton Power Upgrade (PPU) project 

and the Second Target Station (STS)

Work has begun on a Proton Power Upgrade (PPU) at the SNS 

that will increase the neutron flux, or rate of flow of neutrons, 

and significantly increase its capacity to support the national and 

international research community. The PPU is necessary to support 

a Second Target Station (STS), which will be a third neutron source 

at ORNL.

The STS will complement capabilities at the SNS First Target Station 

(FTS) and HFIR by providing new, transformative capabilities for 

materials research and will maintain US competitiveness in materials 

development as new European and Asian neutron facilities come 

online. With a new suite of world-leading instruments boasting 

the latest advances in high-resolution optics, instrument design 

and more, the STS will make it possible to conduct a wide range of 

experiments now not possible anywhere in the world.

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