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September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Inkjet droplets of radioactive material enable quick, precise testing at NIST
Researchers at the National Institute of Standards and Technology have developed a technique called cryogenic decay energy spectrometry capable of detecting single radioactive decay events from tiny material samples and simultaneously identifying the atoms involved. In time, the technology could replace characterization tasks that have taken months and could support rapid, accurate radiopharmaceutical development and used nuclear fuel recycling, according to an article published on July 8 by NIST.
B. Grimeland and G. Seierstad
Nuclear Science and Engineering | Volume 23 | Number 4 | December 1965 | Pages 339-343
Technical Paper | doi.org/10.13182/NSE65-A21070
Articles are hosted by Taylor and Francis Online.
Small crystals of NaI(TI) were exposed to (D, D) neutrons slowed down in a paraffin moderator. The crystals were either enclosed in cadmium or placed inside a small cadmium box filled with the moderator material. The activities induced in iodine at different positions were measured. Now let the normalized activities obtained with the detectors enclosed in cadmium be A1 and let those obtained with the detectors placed inside the cadmium box be A2. It is assumed that the difference A2 − A1 is proportional to q(0.5 eV)-the slowing down density at an energy of 0.5 eV-and from the measured quantities A2(r) and A1(r) the slowing down age has been determined. Bare crystals were also irradiated and the induced activities measured. Let these activities be A3. Then the difference A3 − A1 will give a measure of the density of thermal neutrons and the migration area can be determined. With migration area and slowing down age known, the diffusion length of thermal neutrons could be determined too. The result obtained was L = (2.86 ± 0.16)cm compared to a calculated value of (2.60 ± 0.01)cm. The discrepancy might indicate that the neutron temperature in the paraffin is about 400 °K. Paraffin was used as moderator material because this greatly facilitated the experiment. It is never used as a reactor material and knowledge of the measured quantities may be of minor importance. The method, however, might possibly be of some interest.
