312 Crothers Engineering Hall
South Dakota State University
Brookings, SD 57007
Robert.McTaggart@sdstate.edu
(605) 688-6306
Dr. Robert J. McTaggart
312 Crothers Engineering Hall
South Dakota State University
Brookings, SD 57007
Robert.McTaggart@sdstate.edu
(605) 688-6306
Click on the picture to the right to get to the official Homestake web site.
Martin Harms and Mark West of Aerostar in Sioux Falls help me (in the middle)
launch a high altitude balloon from Turkey Ridge, SD on September 18, 2008.
The balloon reached a maximum height of 76,777 feet before parachuting
down to Rowena, SD.
Physics 316 Measurement Theory
Advanced Physics Lab I
Physics 492 Special Topics: Thermodynamics and Statistical Mechanics
Used to be Physics 341/343
Class information is available via Desire 2 Learn.
Homestake Research:
The Homestake Mine was selected by the National Science Foundation on July 10, 2007 to be its primary choice to become the Deep Underground Science and Engineering Laboratory, a.k.a. DUSEL. Particle Physicists want to go underground to get away from the cosmic ray background that may affect the detection of rare event processes, such as dark matter, proton decay, and neutrino oscillations. Reduction of other sources of background, such as internal radioisotopes and the effects of Radon gas and its progeny, will also be a key component of the lab's development. However, the laboratory will also provide access to other scientists in biology, chemistry, geology, and engineering interested in the underground environment.
Current information regarding the status of Homestake can be found here.
Cross-cutting Applications: I'm currently serving as the working group leader for this multidisciplinary collaboration for Homestake, which used to be called "Effects of Energetic Particles". A pre-proposal to the DEDC (DUSEL Experiment Development and Coordination) has been submitted prior to the release of "S4" by the NSF. S4 essentially covers engineering design costs, while S5 would cover any construction and other experimental costs.
The pre-proposal for the group is available on-line
Laser Isotope Separation and Thermal Diffusion: LIS would ionize naturally-occurring and radioactive Argon-39 by laser light, and then remove it by applying a strong electric field. The technique is somewhat different than separating isotopes by centrifuge or mass spectrometry, but could purify other materials or contribute to a future verification technique. SDSU will support the design and construction of prototypes and the final facility at Homestake for thermal diffusion, which separates different isotopes with convection. SDSU will also participate in the verification of depleted Argon-39 levels.
Low-Level Background Counting Facility: This facility would assay materials brought into the mine for any radioimpurities that could affect the sensitivity of detectors to rare-event physics, such as the detection of neutrinos, dark matter, and proton decay. The shielding of cosmic rays by the rock reduce the amount of background radiation, but incoming material may produce enough static to hinder rare-event physics. The high-purity Germanium detectors can also be used to detect neutrinoless double-beta decay, which tells us if the neutrino has mass and whether it is its own antiparticle. Radon levels in the mine would be surveyed, and a database of radioimpurity content would also be developed. Berkeley, USD, DSU, School of Mines, Augustana, and SDSU would collaborate on the project if funded by DOE EPSCoR.
Materials Free of Cosmic-Ray Defects: Surfaces and crystals as a whole should act differently in a radiation-free environment, which the Homestake Mine will approach. Dislocations and radioactive conversion of elements change the properties of materials, so this may have a lot of applications for new circuits, photovoltaics, advanced particle physics detectors and the study of new alloys that may be produced in the future. These studies would benefit from facilities like those above if they can produce large quantities of ultrapure materials.
Biological Effects of Low Levels of Radiation: For large doses of radiation it is well-known that radiation damage and/or your risk to developing disease from radiation increases linearly with the amount of radiation absorbed. For small doses of radiation, does this linearity still hold? Will cellular mechanisms responsible for the repair of radiation actually continue unabated and produce damage to cells? Is the radiation damage due to individual DNA damage, or are other chemical and biological mechanisms at work? In general the study of the effects of low levels of radiation are important for employees in the nuclear field and the effects of Radon. Furthermore, low levels of radiation may be important for stimulating cellular repair mechanisms, as cells may adapt to the low level environment by not investing resources into said mechanisms.
Non-Homestake Research:
Irradiation of Ethanol Feedstocks: Efforts are underway to irradiate switchgrass, DDG, and corn stalk with gamma radiation and neutrons to see if the irradiation will break up some of the lignocellulosic structure that currently hinders a net energy return from cellulosic feedstocks of ethanol. In the future one may either have a dedicated irradiation facility, similar to the 3M sterilizer in Brookings, or incorporate bioprocessing into plans for future nuclear facilities.
A group from Japan recently found that 500 kGy of Cobalt-60 irradiation of corn cobs and other agricultural products doubled the resulting saccharification. Currently we have irradiated switchgrass, corn stalk, and DDG with 0, 69 kGy, and 331 kGy with gamma radiation at the 3M medical sterilizer in Brookings, which has a Cobalt-60 source. Samples hydrated to 20% have also been delivered to 3M. These and samples irradiated by fast and thermal neutrons at the nuclear research reactor at Kansas State University are being analyzed by Bill Gibbons and Fathi Halaweish at SDSU.
Our first preliminary results on the dry, finely ground samples irradiated at 3M show that irradiation increases the levels of DP4 arising from the analysis, which may mean that bonds are being broken in the cellulosic structure. However the response in the resulting glucose and xylose levels is not as strong.
With the support of 3M, the departments of Physics, Biology & Microbiology, Chemistry and Biochemistry, and the College of Engineering, we are currently proceeding with a study on the effects of hydration on saccharification and sugar profiles, and the production of by-products of irradiation that may potentially inhibit fermentation.
Determination of Selenium in Soils and Plants: Selenium is an antioxidant that is more plentiful on average in South Dakota than other places. Certain markets desire higher selenium content in their beef and wheat. Too much of a good thing however produces selenium toxicity that can kill cattle. We are assessing the technique of neutron activation analysis (NAA) for the determination of selenium concentrations. Selenium comes in several different molecular forms that have different solubilities in water. While NAA can only yield the total amount of selenium, NAA should serve a complementary role to molecular fluoroscopy and other methods in wet chemistry.
Se-74 is a stable isotope that is found in low abundance typically. However Se-75, which is produced when Se-74 absorbs a neutron, has a fairly long half-life. One can let other elements with shorter half-lives decay and get a clean estimate of the Se-75 concentration. Then we divide by the percentage of Selenium that is Se-74 to get the total selenium content. A short irradiation could yield information on the other isotopes to verify that the standard global concentrations of Selenium are accurate (i.e. do different processes deposit more of one isotope than another, are they absorbed preferentially by plants, etc.).
High Altitude Balloon Research: As part of a NASA EPSCoR RIG grant, Aerostar in Sioux Falls helped me launched a high altitude balloon on September 18, 2008 from the Turkey Ridge air field in South Dakota. After reaching a maximum height of 76,777 feet, it landed about 3 hours later near Rowena, SD. The payload for this launch included samples of Fusarium (a type of fungus), several unijunction transistors (UJTs), a digital camera from the EROS Data Center, and three different ethanol feedstocks. Altitude and pressure data can be used to enhance satellite image calibration routines.
Unijunction transistors, which are used to exhibit non-linear behavior such as periodic pulling in circuits, will also be subjected to near-space conditions and characterized in the lab. The question is how do those characteristic curves change after being exposed to radiation or near-space environments. More on UJT's to come. The failure rate, and the testing of strategies to ameliorate said failures, and overall performance in the upper atmosphere for microelectronics and communications can be addressed in future balloon flights.
Fusarium fall into a class of microbes called "extremophiles", which are also being studied underground at the Homestake Mine. Exposure to stressful environments may yield information about the adaptability of early life on earth, and the possibilities of developing life elsewhere in the solar system.
Future launches may include a spore trap to collect biological material in the upper atmosphere, and an aerosol sampler to assay particulate matter. Other applications for astronomy, satellite imaging, and microbial stress testing may also be included.
Development of a Prototype Gamma-Ray Camera: In July 2007 we submitted a proposal to NASA EPSCoR with Augustana and Argonne National Lab to construct and test an array of Multi-Pixel Photon Counters (a.k.a. silicon photomultipliers) under different environmental conditions around the State of South Dakota, Argonne National Lab, and in near-space conditions with high-altitude balloon flights. Ultimately it would be used in the next generation of gamma-ray telescopes like VERITAS to search for evidence of dark matter, dark energy, gamma-ray bursts, new TeV sources of gamma-rays, etc. The proposal was rejected, but it may come back in a different form. Gamma-ray telescopes could benefit from several dark-sky environments available in South Dakota. Such development may also occur in using MPPC's for medical imaging.
Charmonium: The hydrogen atom is a bound state of a proton and an electron governed by a Coloumb-type interaction. The deuteron is a bound state of a proton and a neutron governed by the strong force. Charmonium is a bound state of a charmed quark and its antimatter partner also governed by the strong force. The behavior of the strong force exhibits "asymptotic freedom" at short distances, and "quark confinement" at larger distance. A non-relativistic Schrodinger equation is often applied to predict the energy eigenfunctions and their decays, but a semi-relativistic approach is needed since spin angular momentum plays a large role in splitting the degenerate states.
My Ph.D. thesis was done on the angular distribution of electron-positron pairs from Charmonium decays produced in proton-antiproton annihilations at Fermilab. I am interested in determining the energy eigenfunctions for Charmonium and reproducing the measured angular distributions seen in my thesis. Different potential models and mixing of the S and D states will eventually be included.
Fermi National Accelerator Laboratory
Los Alamos National Laboratory
Brookhaven National Laboratory
"Cross-Cutting Applications at Homestake," USD Teacher Workshop, June 11, 2008.
"Multidisciplinary Activities at Homestake," SDSU Physics Colloquium, May 1, 2008.
April 21-26, 2008. Homestake Workshop in Lead, SD
"Irradiation Pretreatments with Gamma-Rays and Neutrons", SunEthanol/VeraSun/SDSU meeting, November 14, 2007.
"Homestake Update and Future Directions for Physics at SDSU," SDSU Physics Colloquium, November 8, 2007.
"Homestake Electrical Engineering Laboratory," Homestake meeting, February 9-11, 2006.
"Health Physics at the Homestake Mine," Homestake meeting, February 9-11, 2006.
Recent Newspaper Articles
"SDSU Launches High-Altitude Balloon," Argus Leader, September 23, 2008.
"Science in the Sky," Brookings Register, September 23, 2008.
"Clean, secure energy requires nuclear power," editorial in Argus Leader, September 16, 2008.
"Lab Work may start by 2012," Argus Leader, May 13, 2008.
"Homestake Activities could start in 2012," Black Hills Pioneer, May 12, 2008.
