Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
  • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T3/00—Measuring neutron radiation
  • G01T3/06—Measuring neutron radiation with scintillation detectors
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/01—Particle morphology depicted by an image
  • C01P2004/02—Particle morphology depicted by an image obtained by optical microscopy
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
  • C01P2004/13—Nanotubes

Definitions

• BNNT materials there are numerous advantages in utilizing high-quality BNNT materials in embodiments of the present approach.
• BN allotropes to less than 30 wt.% and in some embodiments below 10 wt.%.
• the BNNT materials become optically translucent and allow the light produced by either the scintillating crystals or the BNNT themselves, to reach a photon detector (e.g., a the SiPM or PMT photon detector).
• the BNNT material is under vacuum or partial vacuum.
• the BNNT, boron, amorphous BN, and h-BN in the crystal-coated BNNT material 13 are minimally changed or impacted by neutron absorption Events, provided that the fraction of material interacted with by the neutron absorption does not exceed 5% by weight in most embodiments, and in some embodiments as high as 20% of the overall material as long as the average structural integrity is preserved and the optical transmission of the light is not compromised.
• the range relates to some embodiments having elements that hold the material in place (and therefore the threshold is higher, e.g., around 20%), wherein other embodiments the material is part of the support structure and therefore the threshold is lower (e.g., around 5%).
• BNNT buckypapers have been manufactured in a wide range of sizes, and from all the various BNNT materials referenced herein (e.g., PI, P2, SP-10, Beta, Gamma, and Zeta, R, and RX).
• the BNNT buckypapers used in various embodiments have a thickness from 10 to 200 microns. For an areal density near 1 mg/cm 2 , the thickness is typically 10-20 microns, but other embodiments may extend beyond this range.
• the compressed thickness can become as low as 0.7 microns, however the BNNT buckypapers used in the embodiments discussed herein were not under external pressure.
• a 10 micron 10 BNNT buckypaper is typically near 1 mg/cm 2 , and absorbs 10% of the thermal neutrons impacting the surface.
• BNNT buckypapers having diameters of 3.5 cm and 7 cm were used in many of the prototypes, but other dimensions may be used in other embodiments.
• Figure 2 shows a BNNT buckypaper 21 with a 21.5 cm diameter, formed using BNNT material from BNNT, LLC.
• the BNNT buckypaper 21 is on a filter paper 22 and a sheet of aluminum foil 23.
• BNNT buckypapers have suitable optical properties for the present approach as shown in Figure 3, with a 30 mm small, 1 mg/cm 2 , 30 mm diameter P2 Zeta BNNT buckypaper 31 covering a portion of a pencil 32.
• Anthracene a preferred second scintillating material in the present approach, has the highest scintillation light output of any organic scintillator for a given level of ionization.
• the level of stirring or sonication of the mixture will vary as those of ordinary skill will appreciate.
• the mass ratio of scintillating precursor and BNNT material can be varied depending on the embodiment and the balance of ionization loss of the 4 He and 7 Li ions as discussed above.
• the anthracene crystal-coated BNNT material in the SiPM detector system was less than about half of the amount of crystal-coated BNNT material used for the PMT system and covered roughly one third the area with about half the amount of 10 B present.
• the SiPM used had a very high noise rate in each of the four elements of the quad SiPM so they were put in coincidence utilizing constant fraction discrimination. At least two of the four elements had to have a signal to indicate an Event. The coincidences occurred within a 10 nanosecond window. To determine the base rate from the random coincidences between the elements of the SiPM, the SiPM was covered so it could not collect light from the surroundings, and under these conditions it counted at 119 CPM. This rate was dependent on the bias voltage applied to the SiPM. The challenge of high noise rates in SiPMs is well known by those of ordinary skill in working with them, and future planned work will be with SiPMs that are far less noisy for this application.
• Table 2 shows the SiPM results.
• the Event rate was near a factor of four below that of the PMT rate. This is very roughly a factor of two below the anticipated rate. The discrepancy is believed to be mostly a factor of the issue of noise discussed above in the system as the Event rates were a factor of more than ten below the noise coincidence rate.
• the half width of the pulses observed was near 100 nanoseconds. Again, the SiPM system was not well optimized for the measurement and while the timing was better than 10 nanoseconds, the pulse widths would ideally be narrower. However, the pattern seen with the PMT of the variation in rates between, 0”, 1” and

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• Luminescent Compositions (AREA)

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• 2021
  • 2021-01-21 EP EP21744386.0A patent/EP4094100A2/en not_active Withdrawn
  • 2021-01-21 JP JP2022544118A patent/JP2023510968A/ja active Pending
  • 2021-01-21 US US17/794,161 patent/US20230115203A1/en not_active Abandoned
  • 2021-01-21 WO PCT/US2021/014288 patent/WO2021150665A2/en not_active Ceased
  • 2021-01-21 KR KR1020227027315A patent/KR20220130153A/ko not_active Withdrawn
  • 2021-01-21 CA CA3168037A patent/CA3168037A1/en active Pending

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