In the USA, a powerful third generation neutron sources has been built at Oak Ridge National Laboratory, Tennessee, by the U.S. Department of Energy. The 1.4 MW Spallation Neutron source SNS is fully operational. The construction began in 1999.

SNS is being designed and constructed by a partnership of six U.S. Department of Energy (DOE) national laboratories (Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge).

The SNS deliver 1.4 million watts (1.4 MW) of beam power onto the target, and it has been designed with the flexibility to provide additional scientific output in the future.

The Ion Source - Lawrence Berkeley National Laboratory (LBNL)
The ion source produces negative hydrogen (H- ) ions that are formed into a pulsed beam and accelerated to an energy of 2.5 million electron volts (MeV).

The Linac- Los Alamos National Laboratory (LANL)
Linear accelerator - accelerates the H - beam from 2.5 to 1000 MeV, or 1 GeV.
Three different types of accelerators:
Drift tube linac and the coupled-cavity linac - 200 MeV
Superconducting niobium cavities - Thomas Jefferson National Accelerator Facility (JLab).

The Accumulator Ring- Brookhaven National Laboratory (BNL)
1200 turns - intense proton pulses are produced, stored, and extracted at a rate of 60 times a second to bombard the target.

The Target - Oak Ridge National Laboratory (ORNL)
Liquid mercury target

Moderator
Water (to produce room-temperature neutrons)
Liquid hydrogen at a temperature of 20 K (to produce cold neutrons).

Instrumentation and Experiment Facilities at the SNS - Argonne National Laboratory (ANL)
A variety of instruments will be constructed on the beam lines:
Beam lines:
- one target station operating at a frequency of 60 Hertz (Hz).
- two “thermal” moderators
- two “cold” moderators will be used to service 18 beam lines.

User expected
1000 - 2000/ year

Information extracted from SNS Homepage
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