<p>The study of high power fusion plasmas at the JET tokamak has been further enhanced through the development of instrumentation for neutron emission spectroscopy (NES) measurements. This has involved the upgrade of the magnetic proton recoil (MPR) spectrometer used for deuterium-tritium plasmas earlier so that the MPRu can now be also employed for deuterium (D) plasmas. A neutron time-of-flight (TOF) spectrometer designed for optimized rate (TOFOR) has been constructed and put into operation. The MPRu and TOFOR spectrometers were carried out as part of the JET enhanced performance program and represent the most advanced instrumentation for NES diagnosis of both D and DT tokamak plasmas setting a central platform for R&D direct to the next step in fusion research to be carried out with ITER.</p><p>The MPRu work presented in this thesis concerns the development of a new focal plane detector based on the phoswich scintillator technique. The main objective of this sub-project was to increase the signal-to-background ratio to permit measurement of the 2.5-MeV neutron emission from d+d-->3He+n reactions and, hence, allow NES diagnosis of D plasmas. The objective was achieved as demonstrated in preliminary measurements at JET. </p><p>The development of TOFOR from concept to construction is presented in the thesis including, in particular, the commissioning of the instrument at JET. The objective of the TOFOR project was to achieve the same high performance in the NES diagnosis of D plasmas as had earlier been demonstrated by the MPR for DT plasmas. TOFOR has been used in the first plasma physics experiments reported in this thesis. These demonstrate that the performance objectives have been achieved as tested, in particular, in the observation of auxiliary heating effects on velocity distribution of the deuterium population.</p>

Neutron emission spectra, measured with the time of flight spectrometer TOFOR, at the joint European torus (JET) are presented in this thesis. TOFOR has been in use since 2005, routinely measuring the neutron emission from JET plasmas. The work in the thesis mainly concerns the modeling of the signatures in the neutron spectrum that reveal different parts of the fuel ion distribution, such as the thermal bulk plasma as well as energetic ions from neutral beam and ion cyclotron heating. Parametric models of the signatures, using plasma parameters as input, are employed to generate trial neutron spectra. The parameters, such as the fuel ion temperature or the fast ion distribution function, are deduced by iteratively fitting the trial spectra to the measured data. Measurements with TOFOR have been made and the models were applied. The studies are mainly on neutrons from d(d, n)3 He reactions(DD), although the emission from reactions with the plasma impurity 9 Be and triton burn up is covered as well. This has allowed for detailed studies of e.g. the physics ICRF heating as well as the interactions between energetic ions and plasma instabilities, such as toroidal Alfvé Eigenmodes.

Particle physics experiments with low event rates highly depend on background suppression methods. Neutron component of the ambient background radiation is especially problematic since neutrons are difficult to shield directly. TEXONO collaboration has employed a hybrid neutron detector composed of two different scintillating materials to measure the neutron background directly in the Kuo-Sheng Neutrino Laboratory. Detector is operated after calibration and optimization studies and from collected data, neutron flux is obtained using computational methods.

The study of high power fusion plasmas at the JET tokamak has been further enhanced through the development of instrumentation for neutron emission spectroscopy (NES) measurements. This has involved the upgrade of the magnetic proton recoil (MPR) spectrometer used for deuterium-tritium plasmas earlier so that the MPRu can now be also employed for deuterium (D) plasmas. A neutron time-of-flight (TOF) spectrometer designed for optimized rate (TOFOR) has been constructed and put into operation. The MPRu and TOFOR spectrometers were carried out as part of the JET enhanced performance program and represent the most advanced instrumentation for NES diagnosis of both D and DT tokamak plasmas setting a central platform for R&amp;D direct to the next step in fusion research to be carried out with ITER. The MPRu work presented in this thesis concerns the development of a new focal plane detector based on the phoswich scintillator technique. The main objective of this sub-project was to increase the signal-to-background ratio to permit measurement of the 2.5-MeV neutron emission from d+d--&gt;3He+n reactions and, hence, allow NES diagnosis of D plasmas. The objective was achieved as demonstrated in preliminary measurements at JET. The development of TOFOR from concept to construction is presented in the thesis including, in particular, the commissioning of the instrument at JET. The objective of the TOFOR project was to achieve the same high performance in the NES diagnosis of D plasmas as had earlier been demonstrated by the MPR for DT plasmas. TOFOR has been used in the first plasma physics experiments reported in this thesis. These demonstrate that the performance objectives have been achieved as tested, in particular, in the observation of auxiliary heating effects on velocity distribution of the deuterium population.

A novel broad spectrum neutron spectrometer has been created to extend the useful energy range of existing neutron Bonner Sphere Spectrometers (BSS). Both an active LiI(Eu) scintillator probe and passive gold foil detector were utilized to extend the energy response of the existing BSS. Above 20 MeV the energy structure for the standard polyethylene BSS are poor because the response functions are not unique. MCNPX was used to investigate several modifications to the BSS system which resulted in the Bonner Sphere Extension (BSE). This cost effective extension uses several concentric spheres of copper, lead, and tungsten heavy metal downscatter materials to extend the useful range of the current BSS from 20 MeV to above 1 GeV. Using both a 3" and 5" inner polyethylene spheres, aluminum shell sets were made with a 1" cavity and filled with the high Z materials for six total sets of spheres. a 12" and 8" polyethylene sphere were also milled to accept the heavy metal spheres. The system was validated at the Los Alamos Neutron Science Center (LANSCE) neutron beam. The system was calibrated at LANSCE for neutrons up to 800 MeV on target 4's 15 degree right flightpath (4FP15R) at 90 meters. Detailed models in MCNPX were made of the BSS, BSE and LANSCE facilities. Fine group responses were made and compared to the unfolded data from LANSCE. A vast improvement over the BSS system alone was seen with reasonable agreement with time of flight data measured at LANSCE and MCNPX calculated neutron spectra.

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abstract: Part I – I analyze a database of Smoothed Particle Hydrodynamics (SPH) simulations of collisions between planetary bodies and use the data to define semi-empirical models that reproduce remant masses. These models may be leveraged when detailed, time-dependent aspects of the collision are not paramount, but analytical intuition or a rapid solution is required, e.g. in ‘N-body simulations’. I find that the stratification of the planet is a non-negligible control on accretion efficiency. I also show that the absolute scale (total mass) of the collision may affect the accretion efficiency, with larger bodies more efficiently disrupting, as a function of gravitational binding energy. This is potentially due to impact velocities above the sound speed. The interplay of these dependencies implies that planet formation, depending on the dynamical environment, may be separated into stages marked by differentiation and the growth of planets more massive than the Moon. Part II – I examine time-resolved neutron data from the Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory (MSL) Curiosity rover. I personally and independently developed a data analysis routine (described in the supplementary material in Chapter 2) that utilizes spectra from Monte Carlo N-Particle Transport models of the experiment and the Markov-chain Monte Carlo method to estimate bulk soil/rock properties. The method also identifies cross-correlation and degeneracies. I use data from two measurement campaigns that I targeted during remote operations at ASU. I find that alteration zones of a sandstone unit in Gale crater are markedly elevated in H content from the parent rock, consistent with the presence of amorphous silica. I posit that these deposits were formed by the most recent aqueous alteration events in the crater, since subsequent events would have produced matured forms of silica that were not observed. I also find that active dunes in Gale crater contain minimal water and I developed a Monte Carlo phase analysis routine to understand the amorphous materials in the dunes. / Dissertation/Thesis / Table 1: Giant impact SPH results for Chapter 1 / Table 2: Giant impact SPH results for Chapter 1 / Table 3: Giant impact SPH results for Chapter 1 / Doctoral Dissertation Geological Sciences 2019