A5046544175- Nuclear Physics and Applications
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Astro and Planetary Science
- Planetary Science and Exploration
- Medical Imaging Techniques and Applications
- Radiation Therapy and Dosimetry
- Isotope Analysis in Ecology
- Spacecraft and Cryogenic Technologies
- Particle physics theoretical and experimental studies
- Graphite, nuclear technology, radiation studies
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Advanced X-ray and CT Imaging
- CCD and CMOS Imaging Sensors
- Astrophysical Phenomena and Observations
- Advanced Semiconductor Detectors and Materials
- Gamma-ray bursts and supernovae
- Plasma Diagnostics and Applications
- Radiation Effects in Electronics
- Magnetic Field Sensors Techniques
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Spacecraft Design and Technology
- Astrophysics and Cosmic Phenomena
Lawrence Livermore National Laboratory
2012-2023
United States Department of Energy
2008
Lawrence Berkeley National Laboratory
1997-2005
University of Arkansas at Little Rock
1997-2002
University of California, Berkeley
1999-2002
Abstract The Mars‐moon Exploration with GAmma rays and NEutrons (MEGANE) investigation will use gamma‐ray neutron spectroscopy to measure the elemental composition of Mars' moon Phobos. MEGANE is part Japanese Martian Moons eXploration (MMX) mission that make comprehensive remote sensing measurements both moons Phobos Deimos. MMX also return Earth regolith samples science goals mirror those mission. determine if a captured asteroid or end result giant impact event on Mars, study surface...
A technique has been implemented for improving the 3-D position resolution in a germanium strip detector. By using signals induced on multiple electrodes, of drifting charges can be interpolated to smaller than width strips. Interpolation allows desired achieved with fewest number electronic channels. Applications include portable and space-based instruments where power, cooling, mass are at premium. Measurements were made fully instrumented 19/spl times/19 planar This system is used as...
Three n-type high-purity germanium (HPGe) detectors were irradiated with protons at solar and galactic cosmic ray energies, fluences corresponding to ≥3 years of exposure the interplanetary radiation environment. Following 1 GeV proton irradiations (8×108 cm−2), annealing 105°and 115 °C resulted in full energy resolution recovery after 240 140 h annealing, respectively. A second irradiation, consisting 7.25x109 cm−2 a solar-proton-like spectrum, within <316 105 °C. Prior spaceflight...
Measurements of gamma-ray emissions from the decay cosmogenic radionuclides provide an opportunity to characterize elemental composition a terrestrial planet or asteroid surface. We report on development Geant4 application which models radionuclide production metal-rich surfaces. The model was benchmarked using measurements produced during 1 GeV proton irradiation target made Campo del Cielo iron meteorite. emitting 58Co, 57Co, 56Co, 54Mn, 52Mn, 51Cr, 48V, 46Sc and 22Na were observed...
We have investigated the effects of charge sharing and loss in gap between strips a prototype 19 /spl times/ germanium strip detector. Our measurements indicate some for events occurring strips, find that this "dead" region where is lost (which leads to an underestimated incident photon energy) narrower than physical width, confined small below surface. This illustrated by observing coincidence spectra nearest neighbor as function energy (and therefore interaction depth), confirmed with...
We flew a prototype of the Nuclear Compton Telescope (NCT) on high altitude balloon from Fort Sumner, New Mexico 2005 June 1. The NCT is soft gamma-ray (0.2-15 MeV) telescope designed to study, through spectroscopy, imaging, and timing, astrophysical sources nuclear line emission polarization. Our program develop test technologies analysis techniques crucial for Advanced satellite, while studying radiation with very spectral resolution, moderate angular sensitivity. utilizes two, 3D imaging...
We have developed germanium detector technologies for use in the Nuclear Compton Telescope (NCT) - a balloon-borne soft γ-ray (0.2-10 MeV) telescope to study astrophysical sources of nuclear line emission and polarization. The heart NCT is an array twelve large volume cross strip detectors, designed provide 3-D positions each photon interaction with ~1mm resolution while maintaining high spectral germanium. Here we discuss detailed performance our prototype 19x19 detector, including...
We constructed two small-area pixelated detectors, which can record signals produced by 800-MeV proton beam micropulses with a repetition rate of 358 ns. The first detector was built around two-dimensional (2-D) photodiode array. array illuminated light emitted monolithic 1.7-mm-thick lutetium oxy-orthosilicate (LSO) scintillator and imaged simple optical system. other hydrogen ion chamber operated at 1 to 2.5 atm. anode divided into an 8/spl times/8 mm/sup 2/ pixels. fast positive-ion drift...
Our collaboration is developing a 2-detector prototype high resolution Compton telescope utilizing 3D imaging germanium detectors (GeDs) for test balloon flight in Spring 2003. This instrument full 12-GeD instrument, the Nuclear Telescope. NCT balloon-borne soft gamma-ray (0.2-15 MeV) designed to study astrophysical sources of nuclear line emission and polarization. The program develop technologies analysis techniques crucial Advanced Telescope, while studying radiation with very spectral...
A gamma-ray spectrometer (GRS) has been built and delivered to the MESSENGER spacecraft which launched on August 3, 2004, from Cape Canaveral, Florida. The GRS, a part of seven scientific instruments board MESSENGER, is based coaxial high-purity germanium detector. Gamma-ray detectors have advantage providing excellent energy resolution, critical achieving science goals mission. However, disadvantage that it must operated at cryogenic temperatures (typically /spl sim/80 K). This requirement...
The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2MeV-10MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. A prototype instrument was successfully launched from Ft. Sumner, NM on June 1, 2005. NCT consists two 3D position sensitive High-Purity-Germanium (HPGe) strip detectors fabricated with amorphous Ge contacts. novel ultra-compact design new technologies allow achieve high efficiencies excellent spectral resolution...
Gamma-ray spectroscopy investigations characterize the chemical composition of planetary surfaces by measuring element-characteristic gamma rays with energies ∼100 keV to ∼9 MeV. Over this energy range, mean free path a ray varies from about 1 25 cm, therefore gamma-ray measurements sample subsurface composition. Many elements emit at multiple, often widely spaced energies, so can in principle also be used identify depth-dependent variations We report results laboratory and radiation...
A germanium based gamma ray imager with 3D position sensitivity is being developed. The will detect rays in the range of /spl sim/10 keV to 1.5 MeV and locate their interactions within 2 mm X, Y Z. instrument segmented into 39 orthogonal strips both X directions a pitch. Each channel separately instrumented miniature low-noise charge-sensitive preamplifier followed by shaping timing electronics. Germanium imagers 2-D have recently been developed fully our group. current adds capability for...