In this paper, we report on the radiation resistance of 50-micron thick Low Gain Avalanche Diodes (LGAD) manufactured at the Fondazione Bruno Kessler (FBK) employing different dopings in the gain layer.LGADs with a gain layer made of Boron, Boron lowdiffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced at FBK. These sensors have been exposed to neutron fluences up to φ n ∼ 3 · 10 16 n/cm 2 and to proton fluences up to φ p ∼ 9 · 10 15 p/cm 2 to test their radiation resistance. The experimental results show that Gallium-doped LGAD are more heavily affected by the initial acceptor removal mechanism than those doped with Boron, while the addition of Carbon reduces this effect both for Gallium and Boron doping. The Boron low-diffusion gain layer shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant density.The LGAD design evolves the standard silicon sensors design by incorporating low, controlled gain [1] in the signal formation mechanism. The overarching idea is to manufacture silicon detectors with signals large enough to assure excellent timing performance while maintaining almost unchanged levels of noise [2].Charge multiplication in silicon sensors happens when the charge carriers (electrons and holes) are in electric fields of the order of E ∼ 300 kV/cm [3]. Under this condition, the electrons (and to less extent the holes) acquire sufficient kinetic energy to generate additional e/h pairs by impact ionization. Field values of ∼300 kV/cm can be obtained by implanting an appropriate acceptor (or donor) charge density ρ A (of the order ρ A ∼
BackgroundMolecularly imprinted polymer (MIP) technique is a powerful mean to produce tailor made synthetic recognition sites. Here precipitation polymerization was exploited to produce a library of MIP nanoparticles (NPs) targeting the N terminus of the hormone Hepcidin-25, whose serum levels correlate with iron dis-metabolisms and doping. Biotinylated MIP NPs were immobilized to NeutrAvidin™ SPR sensor chip. The response of the MIP NP sensor to Hepcidin-25 was studied.FindingsMorphological analysis showed MIP NPs of 20–50 nm; MIP NP exhibited high affinity and selectivity for the target analyte: low nanomolar Kds for the interaction NP/Hepcidin-25, but none for the NP/non regulative Hepcidin-20. The MIP NP were integrated as recognition element in SPR allowing the detection of Hepcidin-25 in 3 min. Linearity was observed with the logarithm of Hepcidin-25 concentration in the range 7.2–720 pM. LOD was 5 pM. The response for Hepcidin-20 was limited. Hepcidin-25 determination in real serum samples spiked with known analyte concentrations was also attempted.ConclusionThe integration of MIP NP to SPR allowed the determination of Hepcidin-25 at picomolar concentrations in short times outperforming the actual state of art. Optimization is still needed for real sample measurements in view of future clinical applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-015-0115-3) contains supplementary material, which is available to authorized users.
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