Efficiency limitation of thin film coated planar semiconductor thermal neutron detector

The response of an Al-10B4C coupled neutron detector based on PIPS technology to Cf-252

“…In this work, 10 B 4 C was chosen as the conversion material and a serious of high-quality silicon detectors were prepared. The investigation focused mainly on two aspects: (1) depositing 10…”

“…The most commonly used materials for thermal neutron conversion are 6 Li, 10 B, and 3 He, which have been widely applied [3][4][5]. Figure 1 shows the 1/𝜈 absorption cross-sections for different neutron conversion materials [6].…”

“…In the case of 3 He, its scarcity makes it unsuitable as a commonly used neutron conversion material. It's found that 10 B is a preferred choice of conversion materials since it has a thermal neutron absorption cross-section of 3840 barns for neutrons with an energy of 0.025 eV which is about four times higher than that of 6 Li [7,8]. The primary reaction between neutrons and 10 B is the 10 B(n,𝛼) 7 Li reaction, as shown in equation below.…”

“…The excited 7 Li * will then releases a 480keV gamma ray when it decays to its ground state. For the other path with a branching ratio of 6%, the reaction leads to the ground state of 7 Li with 𝑄 = 2.792 MeV, and the initial kinetic energies of the ejected 7 Li and 4 He are 1.02 MeV and 1.78 MeV, respectively [9][10][11][12][13][14][15]. The average penetration range of the ejected 𝛼 and 7 Li particles in 10 B 4 C material were calculated to be 3.6 μm and 1.75 μm respectively [15].…”

“…Thin film coated semiconductors have been studied and used as neutron detectors for decades. Neutron detectors had been prepared by sputtering 10 B or 6 LiF directly on the sensitive surface of the silicon detector. The thermal neutron detection efficiency was measured to be 0.22% for 500 Å 10 B-coated detector [16], 3.95% for 1.1 μm 10 B-coated detector, and 4.3% for 35 μm 6 LiF-coated detector.…”