U.S. researchers report in the journal Nature on the 15th that they used a new lithium-rich semiconductor material to develop a small neutron semiconductor detector that can be loaded into a pocket. The detector is efficient and stable, either as a portable device for field inspection or on very large detection equipment, potentially becoming the next generation of neutron detectors.
Efficient neutron detectors are critical in many fields, including national security, medicine, astronomy, etc. There are two main types of neutron detectors that are widely used today — gas detectors and flashdetectors. Compared with these two detectors, neutron semiconductor detectors are smaller and have advantages in some areas, making them the focus of some scientists’ research. However, semiconductor materials that can be used for neutron detectors are not easy to find, and lithium is considered an ideal candidate for its excellent neutron absorption. But lithium can break up in water, and for it to be successfully used in neutron detectors, the challenge of integrating lithium into semiconductors and stabilizing it needs to be solved.
This time, researchers at Northwestern University and Argonne National Laboratory discovered a new semiconductor material, LiInP2Se6, a compound made of lithium, vanadium, phosphorus, and selenium. The compound has a good thermal neutron capture cross-section, suitable band gap and effective transfer of charge of the energy band structure, can directly detect the thermal neutron. Its crystal structure is very special, lithium is located inside the metal layer, water can not reach, so can create a working device to keep lithium stable.
Using neutron detectors made from LiInP2Se6, the researchers are highly sensitive and can quickly detect thermal neutrons from very weak sources. It distinguishes neutron signals from other types of nuclear signals, such as gamma rays, and helps prevent false positives. In addition, because it is rich in lithium, it can absorb a large number of neutrons with only a small amount of LiInP2Se6, so the detection equipment made with it can be small enough. The prototype of the device, made by the research team, is small enough to fit in a pocket.
The researchers point out that in all fields, small neutron detectors have a lot of room for application. Their findings will stimulate scientists’ interest in neutron semiconductor detectors, making it possible for semiconductor detectors to replace 3He positive counters.