Purpose: A new type of electronic dosimeter is presented, capable of discerning between the doses of gamma photons and neutrons in a mixed beam as found in boron neutron capture therapy (BNCT). We introduce a real-time dosimeter based on a thick gate field oxide field effect transistor (FOXFET) covered with a neutron converter layer containing gadolinium.
Methods: To sensitize the FOXFET dosimeter to neutron fluxes, a converter layer containing gadolinium oxide particles embedded in photoresines was deposited over the sensor surface. Mixed neutron-gamma field configurations with different neutron energy spectra were used to assess the FOXFET response, considering different thicknesses of the neutron converter layer.
Results: The total gamma sensitivity of the devices resulted to be 43 mV/Gy. The responses of sensors with different converter layer thicknesses irradiated with different neutron spectra are simulated using GEANT4 code. The response to photons is not significantly modified with thin conversion layers when used in water medium.
Conclusions: A real-time dosimeter comprising a pair of FOXFET sensors-only one of them with a gadolinium neutron converter layer-allows the simultaneous measurement of gamma dose and neutron flux during BNCT irradiations.
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http://dx.doi.org/10.1002/mp.15385 | DOI Listing |
Drug Dev Ind Pharm
January 2025
Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
Objective: Boron Neutron Capture Therapy (BNCT) is a novel precision radiotherapy. The key to BNCT application lies in the effective targeting and retention of the boron-10 (B) carrier. Among the various compounds studied in clinical settings, 4-boronophenylalanine (BPA) become the most prevalent one currently.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Berkeley Center for Theoretical Physics, University of California, Berkeley, California 94720, USA and Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
It has long been established that axions could have been produced within the nascent proto-neutron star formed following the type II supernova SN1987A, escaped the star due to their weak interactions, and then converted to gamma rays in the Galactic magnetic fields; the nonobservation of a gamma-ray flash coincident with the neutrino burst leads to strong constraints on the axion-photon coupling for axion masses m_{a}≲10^{-10} eV. In this Letter, we use SN1987A to constrain higher mass axions, all the way to m_{a}∼10^{-3} eV, by accounting for axion production from the Primakoff process, nucleon bremsstrahlung, and pion conversion along with axion-photon conversion on the still-intact magnetic fields of the progenitor star. Moreover, we show that gamma-ray observations of the next Galactic supernova, leveraging the magnetic fields of the progenitor star, could detect quantum chromodynamics axions for masses above roughly 50 μeV, depending on the supernova.
View Article and Find Full Text PDFAdv Mater
December 2024
Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA.
Angew Chem Int Ed Engl
November 2024
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, State Key Laboratory of Petroleum Molecular & Process Engineering, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China.
Branched alkanes, which enhance the octane number of gasoline, can be produced from waste polyethylene. However, achieving highly selective production of branched alkanes presents a significant challenge in the upcycling of waste polyethylene. Here, we report a one-pot process to convert polyethylene into gasoline-range hydrocarbons (C-C) with yield of 73.
View Article and Find Full Text PDFArch Environ Contam Toxicol
November 2024
Geological Survey of Bangladesh, Segunbaghicha, Dhaka, 1000, Bangladesh.
In order to investigate the distributions and possible dispersion mechanism(s) of naturally occurring radioactive materials (NORMs: Ra, Th, and K) from coal-based brick kilns, a systematic set (n = 60) of coal, ash, surface-soil, and subsurface soil samples were analyzed. High-quality analytical data of U, Th and K obtained from HPGe detector and TRIGA Mark-II research reactor-based neutron activation analysis were converted to the corresponding radioactivities. Average (n = 10) radioactivities of Ra, Th, and K in coal samples were 15.
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