Direction Sensitive Neutron Detectors Using Boron Loaded Semiconductors?

Existing portal monitor detectors at port heads and border crossings have several limitations. They are economically efficient detectors that have sufficient enough detection capability to pass the standards requested by the United States government. This paper describes a new design for a portal monitor detector that increases detection efficiency for neutrons as well as add neutron directionality information to the portal monitor. This detector design makes use of a combination of geometric modification coupled with the unique characteristics of the 10B (n,a) reaction. This reaction results in the production of an excited 7Li recoil that decays in flight by isomeric transition to a ground state. The resultant gamma ray can be detected in a gamma ray spectroscopy system and from the Doppler broadening of this gamma ray the direction of the original neutron causing the reaction in 10B can be unfolded. Advantages and disadvantages of this design are discussed.