A5051260183- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Nuclear reactor physics and engineering
- High-pressure geophysics and materials
- Particle Detector Development and Performance
- Planetary Science and Exploration
- Quantum Chromodynamics and Particle Interactions
- Nuclear and radioactivity studies
- Astro and Planetary Science
- Methane Hydrates and Related Phenomena
- Nuclear physics research studies
- Radiation Therapy and Dosimetry
- Phase Equilibria and Thermodynamics
- Particle physics theoretical and experimental studies
- Particle accelerators and beam dynamics
- Ion-surface interactions and analysis
- Rare-earth and actinide compounds
- Nuclear Materials and Properties
- Advanced NMR Techniques and Applications
- Graphite, nuclear technology, radiation studies
- Atomic and Molecular Physics
- High Temperature Alloys and Creep
- VLSI and Analog Circuit Testing
Johns Hopkins University Applied Physics Laboratory
2012-2025
Indiana University Bloomington
2003-2019
Johns Hopkins University
2012
Abstract Recent theoretical and experimental findings suggest the long-known but not well understood low temperature resistance plateau of SmB 6 may originate from protected surface states arising a topologically non-trivial bulk band structure having strong Kondo hybridization. Yet others have ascribed this feature to impurities, vacancies reconstructions. Given typical methods used prepare single crystals, flux floating-zone procedures, such ascriptions should be taken lightly. We...
We report the first observation of charge symmetry breaking $d+d\ensuremath{\rightarrow}^{4}\mathrm{H}\mathrm{e}+{\ensuremath{\pi}}^{0}$ reaction near threshold. Measurements using a magnetic channel (gated by two photons) $^{4}\mathrm{H}\mathrm{e}$ scattering angle and momentum (from time flight) permitted reconstruction ${\ensuremath{\pi}}^{0}$ ``missing mass,'' quantity used to separate $^{4}\mathrm{H}\mathrm{e}+{\ensuremath{\pi}}^{0}$ events from continuum double radiative capture...
We report angular distribution measurements of the differential cross section $\ensuremath{\sigma}(\ensuremath{\theta})$ and analyzing powers ${\mathit{iT}}_{11}(\ensuremath{\theta}),{T}_{20}(\ensuremath{\theta})$, ${T}_{22}(\ensuremath{\theta})$ for deuteron-deuteron elastic scattering at 231.8 MeV. These data are compared to calculations based on lowest order terms in Born series expansion Alt-Grassberger-Sandhas equation four nucleons interacting through CD Bonn potential.
We review a simple gamma ray spectrometer constructed on solderless breadboard. The spectrometer's detector consists of CsI(Tl) scintillator and silicon photomultiplier (SiPM) its readout is facilitated by an Arduino UNO. system low cost utilizes minimum components while still achieving satisfactory charge linearity noise levels. This instrument can be used in instructional laboratories to introduce both radiation detection analog signal processing concepts. also expect it will interest...
The variation of remotely sensed neutron count rates is measured as a function cratercentric distance using data from the Lunar Prospector Neutron Spectrometer. rate, stacked over many craters, peaks crater centre, has minimum near rim, and at larger distances, it increases to mean value that up 1% lower than rate observed crater. A simple model presented, based upon an analytical topographical profile for craters fitted Orbiter Laser Altimeter (LOLA). effect topography coupled with beaming...
We present the results of an ultracold neutron (UCN) production experiment in a pulsed-neutron beam line at Los Alamos Neutron Scattering Center. The experimental apparatus allows for comprehensive set measurements UCN as function target temperature, incident energy, volume, and applied magnetic field. However, low counting statistics signal can be overwhelmed by large background associated with scattering primary cold-neutron flux that is required production. have developed subtraction...
We present results demonstrating neutron detection via a closely spaced converter structure coupled to low pressure noble gas scintillation instrumented by single photo-multiplier tube (PMT). The is dispersed throughout the volume using reticulated vitreous carbon foam coated with boron carbide (B4C). A calibrated cold beam used measure properties, thin film of enriched 10B as reference standard. Monte Carlo computations ion energy deposition are discussed, including treatment random...
We report here the construction and neutron transmission test results of an in-situ polarized 3He-based polarization analyzer system for Magnetism Reflectometer at Spallation Neutron Source, Oak Ridge National Laboratory. The uses Spin-Exchange Optical Pumping method to polarize 3He nuclei a cell gas. Polarized neutrons scattered from sample are intercepted by gas which strongly absorbs in one spin-state while allowing most other pass through. To maintain stable analyzing efficiency during...
We present the results of experiments applying a large area tiled array silicon photomultipliers (SiPM) to gamma ray spectroscopy with 50.8 mm diameter NaI(Tl) and CsI(Tl) scintillators 25.4 CeBr3. These are many times larger than an individual SiPM, largest which 36 mm2 at present. This work compares two methods summing 64 SiPMs into single output signal for use standard charge integration electronics. The straightforward passive method, simply combines all anode cathodes together, active...
It is generally accepted that the main cause of ultracold neutron (UCN) losses in storage traps upscattering to thermal energy range by hydrogen adsorbed on surface trap walls. However, data which this conclusion based are poor and contradictory. Here we report a measurement, performed at Los Alamos National Laboratory UCN source, average flux upscattered neutrons after interaction with bound semicrystalline polymer PMP (trade name TPX), [C${}_{6}$H${}_{12}$]${}_{n}$. Our analysis, mcnp code...
An accelerator-based facility for simulation of neutron-induced single event effects in electronics is under development at Indiana University Cyclotron Facility. The neutron spectrum has been characterized using foil activation techniques and calibrated transistors
Silicon photomultipliers (SiPMs) from various manufacturers are shown to be sensitive gamma-ray ionizing radiation without being coupled a scintillator. Survey measurements of units Hamamatsu, SENSL, and KETEK shown, followed by detailed SENSL. Pulseheight spectroscopy gamma-ray-induced signals reveals large pulses in excess 16 microcells excited per event as ~100 microcells. We review other examples direct excitation found the literature surmise effect that is related scattered charged...
A new pulsed neutron source is under construction at the Indiana University Cyclotron Facility (IUCF). Neutrons are produced via (p,n) reactions by a low-energy proton beam incident on thin beryllium target. The tightly coupled to cold methane moderator held temperature of 20 K or below. resulting time-averaged flux expected be comparable that Intense Pulsed Neutron Source (IPNS) facility Argonne National Laboratory. initial experimental suite will include instrumentation for small angle...
This paper presents a calculation of the neutron cross-sections in solid materials (used practical sources) with large coherent scattering contribution. In particular, dynamic structure function S(Q, $\omega$) polycrystalline ortho-D$_2$ is evaluated using Monte-Carlo that performs an average over angles relative to crystal axes random orientations. method uses analytical dispersion force constants derived from data single D$_2$ framework axially symmetric tensor. The resulting two...
There is interest in developing the ability to rapidly compute energy dependent neutron flux within a complex geometry for variety of applications. Coupled with sensor response function information, this capability would allow direct estimation behavior multitude operational scenarios. In situations where detailed simulation not warranted or affordable, it desirable possess reliable estimates field practical scenarios which do require intense computation. A tool set kind provide quantitative...