What is LENS?

The Low Energy Neutron Source (LENS) is a novel, university-based pulsed neutron source at the Indiana University Integrated Science and Accelerator Technology Hall (formerly the Indiana University Cyclotron Facility). The source utilizes a low energy p-n reaction in Be coupled with a high-current, variable-pulse-width proton accelerator to produce either short or long neutron pulses. A highly optimized moderator produces cold and very cold neutrons for use by a suite of neutron scattering instruments and development facilities.

How LENS Works

  1. There is an ION SOURCE where protons are removed from hydrogen atoms.

  2. There is an ACCELERATOR where these protons are given enough speed to penetrate to the nuclei of beryllium and knock neutrons out of the nucleus. These high speed protons are referred to as a beam.

  3. The MODERATOR contains the beryllium metal target, which is located at the center. The neutrons that come out of the beryllium quickly go into other materials that surround the target. Here they collide with other nuclei. But instead of making nuclear reactions, they merely slow down with each collision. Eventually they have only 1 part per billion of their original energy. For each beam line, holes in the moderator material allow these slow (low energy) neutrons to escape.

  4. Each neutron is associated with a quantum mechanical wave. Because the neutrons are traveling so slowly, the length of this wave gets bigger by about a factor of 100,000 so that it is about the size of an atom or a molecule. The interaction of this wave with various materials allows researchers to study the properties of the material. So along each line there is an INSTRUMENT that measures the effect of the material on the neutron’s wave by looking at the way that it scatters. From this information, researchers can learn about the arrangement of atoms, the sizes and shapes of molecules (such as proteins), and the properties of surfaces. One can even use the neutrons to form a radiographic image of the inside of the material.