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Thermal Neutron capture by 10 B. Neutron Capture cross section [barns]. Element. B isotopes in dielectric, packaging or as substrate doping n capture by 10 B creates an highly ionising a particle Most n captures in 10 B are around Maxwell peak where E n ≈ 0.025 eV.
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Thermal Neutron capture by 10B Neutron Capture cross section [barns] Element • B isotopes in dielectric, packaging or as substrate doping • n capture by 10B creates an highly ionisinga particle • Most n captures in 10B are around Maxwell peak where En ≈ 0.025 eV
The 10B(n,a)7Li reaction Thermal Neutron Capture • Both the a particle and the 7Li recoil can upset a memory cell • 90% of these events are from n with En < 15 eV • 95% of these events are from n with En < 60 eV • → we will have many low energy n in the LHC underground areas
Reducing the SER from thermals • Eliminate the BPSG layer between the silicon and the metallization layer • Apply shi • Shielding package for individual components on a PCB : • Boron nitride (B4C) with polyimide layer • Mold compound with BPSG filler instead of normal silica • … metal metal metal layer metal layer BPSG PSG BPSG PSG n+ n+ n+ n+ p+ p+ p+ p+ p+ p+ p p n n Si Substrate Si Substrate “old” electronics “new” electronics
Radmon SRAM memories x-sections 512k by 8 bit configuration 32 pin functionality 3-5 Volt powering plastic Thermal Fast Toshiba TC554001FL-70L 9827 0.5 mm 8.7e-15 8.4e-15 Toshiba TC554001AL-70L 9929 0.4 mm 2.7E-15 (1) 7.8e-15 2.5E-15 (2) 1.1e-14 (1) Measured with NPL laboratories Teddington UK D beam on Be target using runs with and without cadmium (2) Measured with PROSPERO reactor in thermalised n spectrum With and without cadmium