Request Expert

He has designed and built electronics for spaceflight and stratospheric balloon payloads. These electronics systems have included embedded computers running real-time and Linux operating systems, data acquisition electronics, particle detector electronics, and low-speed control systems. In each case, a small team of scientists and engineers, under his direction, provided low-cost electronics on tight schedules. Typical time scales, concept to manufacturing, are about three years, budget-limited.

CREAM: The CREAM stratospheric balloon experiment, flown multiple times over Antarctica, has an embedded computer system running a customized Linux distribution. The system reads out a series of particle detectors and measure high-energy particles from outer space. The system has dual computer boards for survival redundancy and a robust switchover system for the dual systems. Dual boot sources, dual Ethernet readout channels, and dual data repositories are also included in the system. All of the subsystems are Commercial Off-The-Shelf (COTS) modules with customized interconnections. Technologies used include USB, GPS, Ethernet, SSD, fast digital IO, PC/104, Linux, real-time Linux, and thermal-vacuum testing.

ANITA: The ANITA stratospheric balloon experiment has also been flown multiple times, for nearly a month each time, over Antarctica. Its embedded computer system is a COTS CompactPCI x86 system modified for passive cooling (no convective cooling at 120,000 feet). Reliability is promoted by especially strong burn-in procedures and software testing. The CPU and other subsystems are a mix of COTS and ruggedized COTS. Multiple redundant data storage systems are employed for ease of data recovery and safety. Technologies used include CompactPCI, PCI, PXI, USB, inertial navigation systems (INS), GPS, Ethernet, SSD, extended backplanes, Linux, Acromag, and thermal-vacuum testing.

He is a former professor of physics and astrophysics at the Universities of Hawaii and Minnesota. His physics, astronomy, and astrophysics backgrounds are extremely broad, from acoustics to x-ray sources. His academic career began at the University of Chicago where he studied general relativity initially, but then discovered more interest in experimental physics than in theoretical. He later worked with the John A. Simpson research group at Chicago's Laboratory for Astrophysics and Space Research. His work with cosmic ray particles using data from the Ulysses and CRRES spacecrafts resulted in a Ph.D. thesis on radioactive isotopes in the Galaxy.

Expert moved to Penn State University and joined efforts there aimed at the highest energy particles in space, and in studies of antimatter in the cosmic radiation. These projects were the highly successful Pierre Auger Observatory and the HEAT balloon-borne experiment. Later, as a professor of physics at the University of Minnesota, he joined new efforts in neutrino astrophysics, the ANITA experiment, and projected experiments IceRay and SalSa. These projects rely on the radio frequency (RF) broadband emission of particle showers traversing materials. He finished his academic career at the University of Hawaii working on these same projects.

His work as a researcher was complemented by teaching courses ranging from introductory through graduate courses in physics. For an introductory Energy and the Environment course he wrote a new textbook exploring both existing energy, and potential future energy, sources. His Physics of Music class was especially well-regarded, and popular with both science and music students. His notes are in the process of being turned into a book.

Other areas of research f included particle detectors, fast read-out electronics, wideband antennas, and nanosecond pulse systems. These are hardwares directly related to the cosmic ray physics work. Further afield his interest in acoustics, both from a musical and an architectural standpoint, has been long-standing with a number of projects with music studios in Chicago and State College, PA and performance halls in State College, PA and the Minneapolis-St. Paul (Twin Cities) area.

In any area of physics for which he is not an expert, he could quickly direct, and possibly introduce, you to the relevant authorities. He is also willing to learn new material at any point in time. Several of his projects as an academic, and a number of consulting projects, have been taken on specifically to learn new areas and new applications.

In addition to expertise in particle astrophysics, he has also had a hand in innovative detector development for particle and nuclear physics. These detectors include radio pulse detectors for charged particle cascades, fast leading-edge discriminating scintillation counters, microwave atmospheric shower detectors, and novel methods of fast digitalization of scintillation, Cherenkov, and radio signals.

Particle physics is a very large field and one that often encourages extreme levels of specialization. Research and training in astroparticle physics (studying the cosmic radiation) lends itself to a broader perspective of necessity. Typical experiments involve 10-50 people collaborating on the experiment as opposed to the 200-2000 people in an accelerator-based particle physics experiment. There is far more opportunity to have hands-on experience with multiple hardware, software, and analysis tasks. This was one of the primary advantages of cosmic-ray physics to him: the chance to be a generalist.

He originally came to radio frequency (RF) antennas and electronics via the so-called Askaryan phenomena of radio emission from particles traveling through matter. This emission is broadly similar to Cherenkov light emission, and is a critical tool for detection of ultrahigh-energy neutrinos (ANITA and related projects). Radio engineering was an unfamiliar topic to Expert at the time (circa 2001) so it was especially interesting to dive in and become a subject matter expert.

The Askaryan phenomena produces extremely short pulses (sub-nanosecond) of considerable power (total energy for the neutrinos of interest is greater than a Joule). To detect such pulses, very wideband antennas (up to an order of magnitude in frequency) and components are required. This led to an interest in the design and construction of broadband antennas in a wide range of scales.

Typical antennas: 1-25MHz polarized (wire based), 100-1000MHz dual polarization (horn), 250-2000MHz polarized (planar), 2-11GHz (planar), and 4-11GHz, 4-15GHz, and 6-20GHz polarized (strip line)

Additional competences include electromagnetic interference (EMI), electromagnetic compatibility (EMC), and electromagnetic pulse (EMP) testing.

He has been involved in the conceptual design, planning, and proposal stages of UNEX, SMEX, and MidEX class NASA Explorer missions. Several of those projects converted over to the suborbital division, flying the payloads ultimately as balloon experiments. Thermal, radiation, vacuum, and safety standards are quite similar.

See also the aerospace summary, and the physics summary for the relevant experiments.

Expert one of the world's foremost authorities on cosmic ray physics, the extraterrestrial particle radiation, over all energy ranges. His experimental and theoretical work has included solar energetic particles (keV-MeV energy scales), the anomalous cosmic rays (MeV), Galactic cosmic ray composition, abundances, and source (MeV-GeV), high-energy cosmic rays and antiparticles (GeV-TeV), and air shower ultra-high energy cosmic rays and neutrinos (PeV-EeV and up!).

He managed a complex process of selecting a vendor and managing quotations on a $4M order for electronics assemblies with some custom modifications to parts specified. The final quotation, which was selected, was nearly $250,000 lower than initial informational quotes. This cost savings was after multiple engineering change orders.He led an efficiency analysis for the construction, testing, and deployment of weather stations into remote field sites. The analysis led to a dramatic reduction in unit failures at a small increase in up-front assembly costs. The total cost savings were estimated at over $100,000.He undertook an analysis and verification of the algorithms used by a medical insurance firm in modeling procedure efficacy. This work followed the algorithm from initial concept and directions to the programmers, through the software implementation, and finally to the processed data. The data-flow process was verified to agree with the original stated goals of the algorithm and to be in accord with legal documentation. The potential legal penalties were approximately $400,000.He selected a test and measurement solution for an ultrawideband outdoor antenna range. The total cost of specifying the solution was less than a quarter quoted by another agency.He measured the acoustic properties of a Minneapolis concert hall and made recommendations to the architecture firm for making significant improvements during an upcoming renovation.