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<p>This dissertation describes work conducted in pursuit of interests in adapting Tension
Metastable Fluid Detectors (TMFDs) for dosimetry-related applications with the specific
intent of engineering a neutron ambient dose spectrometer. TMFDs possess several charac-
teristics desirable for neutron spectrometry, including high efficiencies, complete blindness
to gamma and beta radiation, and tailorable-threshold response functions. Prior spectro-
scopic work with TMFDs, aptly named Single Atom Spectroscopy (SAS), was constrained
to a specific subset of detection fluids who’s composition includes hydrogen and only one
other higher Z element (e.g. hydrocarbons), where only one element is assumed capable of
initiating a cavitation detection event (CDE). The present work alleviates these restrictions,
enabling spectroscopy in detection fluids with multiple constituent elements.
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<p>Simulating the detector’s response predicates knowledge of the energy necessary for ra-
diation induced nucleation, which has been theoretically derived with nucleation theory for
superheated fluids, but remains unbeknownst for tensioned metastable states. This limi-
tation was overcome using MCNPX-PoliMI to model the spatial recoil nuclei spectra from
isotope sources and coupled with SRIM to generate the ion energy deposition probabil-
ity density within a critical length scale of each interaction event. Thereafter, the energy
deposition threshold necessary to generate a detection event, and corresponding response
matrix, was derived empirically by solving for the solution curve that minimizes the residual
difference between the measured and simulated count rates.
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<p>The accuracy of the derived response matrix was evaluated through comparisons with a
6LiI Bonner Sphere Spectrometer in which, for 252Cf and 239PuBe/241AmBe isotope source
neutron spectra, the two systems offered results within ±10% of each other for ambient
equivalent fluences on the order of 100 μRem/hr fields. Notably, when under ultra-low (10
μRem/hr) fields the Bonner spectrometer and other traditional detectors proved impractical.
In contrast, the TMFD system was capable of resolving underlying spectral features and
corresponding ambient dose rates within ±5% of MCNP predictions.
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| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/14522682 |
| Date | 30 April 2021 |
| Creators | Anthony A. Sansone (5930228) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Neutron_Spectroscopy_Development_in_Tensioned_Metastable_Fluid_Detectors/14522682 |
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