The new detector, described at the March Meeting of the American Physical Society* by Charles Clark, a Fellow of the Joint Quantum Institute of NIST and the University of Maryland, promises to improve existing neutron measurements and enable tests of new phenomena beyond the Standard Model, the basic framework of particle physics.
The prototype laboratory device is based on a process first observed by the research team: the emission of light from hydrogen atoms produced when neutrons are absorbed by helium-3 atoms (3He). Lyman alpha light, discovered by Harvard physicist Theodore Lyman in 1906, results from the jump between the two lowest-energy states of the hydrogen atom. Although it is the brightest light emitted by the sun and is one of the most abundant forms of light in the universe, Lyman alpha is invisible to the eye because it lies in the far ultraviolet region of the optical spectrum. It is strongly absorbed by most substances and can travel through only about a millimeter of air.
Helium gas, however, does not absorb Lyman alpha light. When a neutron is absorbed by a helium-3 atom, one atom of hydrogen and one atom of tritium (a heavy form of hydrogen) are produced. These atoms fly apart at high speeds, can be excited by collisions with surrounding helium gas, and subsequently emit Lyman alpha light. This light is recorded by the new device, known as the Lyman alpha neutron detector (LAND).
Using an ultracold neutron beam at the NIST Center for Neutron Research, the research team has discovered that Lyman alpha light is generated with surprisingly high efficiency: about 40 photons are generated per neutron for helium gas at atmospheric pressure. According to Alan Thompson, neutron expert on the team, “This device thus has the potential to detect both single neutrons and large numbers of neutrons, which is very difficult to do with present neutron detectors based on electrical discharges.”
The use of an optical means of detection, rather than an electronic one, also offers the prospect of at least a hundredfold improvement in neutron detectors’ dynamic range (the spread in recordable neutron intensity from faint to bright). This stems from the fact that optical detectors respond more quickly than electronic detectors (which suffer from longer periods of inactivity known as “dead time.”)
With further development, this new method can potentially lead to better measurements at existing neutron facilities (for example, neutron diffraction instruments at the NIST Center for Neutron Research) and enable new tests of physics beyond the Standard Model. Measurements at NIST of a property in neutrons known as the electric dipole moment and more precise measurements of the neutron lifetime are planned.
Ben Stein | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Science Education
23.07.2018 | Health and Medicine
23.07.2018 | Life Sciences