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!
'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics
Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences