Missouri Research Reactor Research Articles

Locating the Quispisisa Obsidian Source in the Department of Ayacucho, Peru

AbstractIn 1999, the Quispisisa source of obsidian was located in the Province of Huanca Sancos in central Ayacucho near the village of Sacsamarca. This discovery has been confirmed at the University of Missouri Research Reactor (MURR) by comparing the neautron activation analyses of source samples with artifacts. The Quispisisa source of volcanic glass provided the raw material for most of the obsidian artifacts utilized in central and northern Peru throughout prehispanic times.

Production of No-Carrier-Added105 Rh from Neutron Irradiated Ruthenium Target

Nuclear medicine radiotherapy involves the administration of a radiolabelled drug whose purpose is tissue damage and/or destruction at the point of localisation. Radionuclides useful for this application are those which emit particles (that is alpha, beta or Auger electrons) because they deposit their decay energy over a relatively short range (for example, at the tumour site). Rhodium-105 is a radionuclide with desirable nuclear properties for therapeutic applications (its half-life is 35.4 hours, the maximum α- energy is 0.56 MeV and it produces a 319 keV γ-ray suitable for imaging). However, this radionuclide is not readily available to most of the interested investigators due to the difficulty in production scale-up. The work reported here was designed to develop a viable method to produce and purify multi-millicurie quantities of 105Rh for radiotherapy research. Rhodium-105 was produced at the University of Missouri Research Reactor by the nuclear reaction, 104Ru (n, γ) → 105Ru (β- decay) → 105Rh and a new procedure was developed to chemically separate the no-carrier-added 105Rh from the neutron irradiated ruthenium target. Rhodium-105 production yields, for 10 runs, averaged about 5 mCi per milligram of ruthenium from a 72-hour irradiation at a thermal neutron flux of 8 × 1013 neutrons cm-2 s-1. Rhodium-105 was successfully isolated from the ruthenium radionuclides and the non-radioactive ruthenium. This new separation technique was fast (a total time of 3 hours) and highly efficient for removing the ruthenium. The decontamination factor of ruthenium averaged 16,600, indicating that only 0.006 per cent of the ruthenium remained after separation.

Scalar Aharonov-Bohm effect with longitudinally polarized neutrons

In the scalar Aharonov-Bohm effect, a charged particle (electron) interacts with the scalar electrostatic potential U in the field-free (i.e., force-free) region inside an electrostatic cylinder (Faraday cage). Using a perfect single-crystal neutron interferometer we have performed a ``dual'' scalar Aharonov-Bohm experiment by subjecting polarized thermal neutrons to a pulsed magnetic field. The pulsed magnetic field was spatially uniform, precluding any force on the neutrons. Aligning the direction of the pulsed magnetic field to the neutron magnetic moment also rules out any classical torque acting to change the neutron polarization. The observed phase shift is purely quantum mechanical in origin. A detailed description of the experiment, performed at the University of Missouri Research Reactor, and its interpretation is given in this paper.

Investigation of recoil collection method for production of high specific activity nuclear medicine isotopes.

High specific activity radiopharmaceuticals cannot readily be produced by (n, gamma) reactions in nuclear reactors, because the great abundance of parent atoms remaining have the same chemical characteristics as the produced isotope. We have investigated the effectiveness of using recoil atom collection methods for separating the produced radioisotope. Gold-198, produced from isotopically pure (natural) gold-197, was chosen for these experiments, which were run in the high flux (approximately 10(14) n/cm2 s thermal flux) of the reflector of the University of Missouri Research Reactor. Seven separate experiments were run, with a 2 mm separation between the emitter and the collector. Collection efficiencies were only a few percent of the radioisotope atoms produced in the top atomic layer of the emitter, instead of the 30% range anticipated. Furthermore, the collected radioisotope, instead of being nearly pure, contained a large quantity of the parent. Unless the reason for the "contamination" of product with the parent can be reduced by several orders of magnitude, this "surface hot atom recoil" method appears to offer no practical application for nuclear medicine isotope production.

Longitudinal study of iodine in toenails following IV administration of an iodine-containing contrast agent

The literature on the relationship between diet and thyroid cancer (TC) risk and the higher incidence of TC among Asian immigrants to the US compared to second and third generation subgroups has prompted epidemiologists to hypothesize that increased levels of iodine consumption may be associated with TC risk, particularly among persons with a history of clinical or subclinical thyroid dysfunction. At the University of Missouri Research Reactor (MURR), we have applied epiboron neutron activation analysis to investigate human nails as a dietary monitor for iodine. Preliminary studies have indicated a positive correlation between dietary iodine intake and the concentration of iodine in toenails. However, these studies are confounded by high iodine levels (up to 30 ppm) in approximately 5% of the nails studied. We hypothesize that, in the subjects we have studied, the high iodine levels may be due to iodine-containing medications, in particular contrast-agents containing iopamidol. This paper will report on longitudinal studies using contrast agent subjects who were followed-up for almost two years compared to a longitudinal control and a population mean. Based on this study, we suggest that iodine-containing contrast agents contaminate nail samples via non-specific binding in the short term followed by incorporation in the nail as a result of absorption.

Neutron interferometry instrumentation at MURR

During the last two decades more than 35 fundamental quantum interference experiments have been performed using the perfect-silicon-crystal neutron interferometer. About one-half of these experiments have been carried out at the University of Missouri Research Reactor Center (MURR). In this paper we describe in some detail the instrumentation and the neutron optics of the two neutron interferometry setups currently situated at this 10 MW reactor.

Reactor-produced radionuclides at the University of Missouri Research Reactor

A revolution in radiotherapy has been developing in recent years, based on more sophisticated targeting methods including radioactive intra-arterial microspheres, chemically-guided bone agents, labeled monoclonal antibodies, and isotopically-tagged polypeptide receptor-binding agents. The isotopes of choice for these applications are reactor-produced beta emitters such as Sm-153, Re-186, Re-188, Ho-166, Lu-177, and Rh-105. The University of Missouri Research Reactor (MURR) has been in the forefront of research into means of preparing, handling, and supplying these high specific activity isotopes in quantities appropriate not only for research, but also for patient trials in the U.S. and around the world. Considerable effort has been expended to develop techniques for irradiation, handling, and shipping isotopes worldwide. The MURR has also served as a highly reliable production source for isotopes, with one of the best operating histories of any isotope production reactor in the world.

Observation of geometric and dynamical phases by neutron interferometry

The total phase acquired during an evolution of a quantal system has two components: the usual dynamical phase, $\ensuremath{-}1/\ensuremath{\Elzxh}\ensuremath{\int}H(t)dt,$ given by the integrated expectation value of the Hamiltonian, and a geometric phase ${\ensuremath{\Phi}}_{G}(C)$ which depends only on the geometry of the curve traced in ray space. We have performed an interference experiment using polarized neutrons which clearly demarcates the separate contributions of the dynamical and geometric phases to the total. In the experiment, the two phases arise from two distinct physical operations, a translation and a rotation of a spin flipper within the interferometer, respectively. This work also constitutes the first direct observation of the Pauli anticommutation; a purely geometric phase shift of \ensuremath{\pi} radians appears after a reversal of the current in one of the spin flippers. The experiment was carried out at the 10 MW University of Missouri Research Reactor using a skew-symmetric perfect-silicon-crystal neutron interferometer. A detailed description of the experiment and its interpretation is given in this paper.

Production of radiolanthanides and radiotherapy research at MURR

Many lanthanide radionuclides, having various nuclear properties but similar chemical properties, are considered suitable for different radiotherapeutic applications. This paper describes the production of a number of radiolanthanides (e.g.153Sm,166Dy,166Ho,161Tb and177Lu) and the radiotherapy research involving these radionuclides at the University of Missouri Research Reactor Center (MURR).

Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol.

Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

Determination of iodine in urine, using epithermal instrumental neutron activation analysis (EINAA), at the University of Missouri Research Reactor (MURR)

There is currently great interest in iodine as a micro nutrient. Both high and low intakes have been associated with thyroid cancer incidence. Development of dietary iodine monitors is needed to supplement the use of dietary recall methods which have not been well validated for iodine. In this study, 30 pooled urine samples, from ethnic groups on various islands in the South Pacific, were analyzed for iodine using epithermal instrumental neutron activation analysis (EINAA).

Determination of iodine in human nails via epithermal neutron activation analysis

An epithermal instrumental neutron activation analysis (EINAA) method, using a boron nitride irradiation capsule compatible with use in the University of Missouri Research Reactor pneumatic-tube irradiation facility, has been developed for the analysis of iodine in human nails. The principal objective was to determine if the nail could be used as a means of monitoring dietary intake of iodine. The EINAA method was used to analyze nails from subjects having iodine intakes that could be qualitatively differentiated. Iodine concentrations in nails from these subjects were positively correlated with apparent iodine intake.

Production of no-carrier-added 64Cu from zinc metal irradiated under boron shielding.

Positron emission tomography offers advantages for radioimmunodiagnosis of cancer but requires radionuclides of appropriate half-life that have high specific activity and high radio-purity. This work was designed to develop a viable method to produce and purify 64Cu, which has high specific activity, for positron emission tomography. 64Cu was produced at the University of Missouri Research Reactor by the nuclear reaction, 64Zn(n,p)64Cu. Highly pure zinc metal (99.9999%) was irradiated in a specially designed boron nitrite lined container, which minimized thermal neutron reactions during irradiation. A new two-step procedure was developed to chemically separate the no-carrier-added 64Cu from the zinc metal target. 64Cu recovery for 24 runs averaged 0.393 (+/- 0.007) mCi per milligram of zinc irradiated. The boron-lined irradiation container reduced unwanted zinc radionuclides 14.3-fold. Zinc radionuclides and non-radioactive zinc were separated successfully from the 64Cu. The new separation technique was fast (2 hours total time) and highly efficient for removing the zinc. The zinc separation factor for this technique averaged 8.5 x 10(-8), indicating less than 0.0000085% of the zinc remained after separation. Thus far, the highest 64Cu specific activity at end of irradiation was 683 Ci/mg Cu, with an average of 512 Ci/mg Cu for the last six analyzed runs. The boron-lined irradiation container has sufficient capacity for 75-fold larger-sized zinc targets (up to 45 g). The new separation technique was excellent for separating 64Cu, which appears to be a radionuclide with great potential for positron emission tomography.

Neutron and Gamma-Ray Scattering at the University of Missouri Research Reactor Center

ABSTRACTThe neutron and gamma-ray scattering facilities at the University of Missouri Research Reactor Center include six elastic and inelastic neutron scattering instruments currently in operation and three additional ones under construction. A gamma-ray diffraction and quasi-elastic spectrometer are also available. The Center has no formal user program, but encourages external collaborative work particularly that involves graduate student thesis research.

One-Dimensional Sans Employing Bent-Single Crystal Optics: Theory and Demonstration

ABSTRACTA recent small-angle neutron scattering (SANS) instrumentation development at the University of Missouri Research Reactor Center (MURR) using bent, double Si crystal diffraction is presented. Neutron rocking curves of flat single crystals are only a few seconds of arc with correspondingly low integrated intensities. The rocking curve can be significantly broadened if the crystals are bent. However, the phase-space acceptance and emergence windows of two bent crystals in parallel can be matched only if the reflecting planes have different d-spacing. We have used a combination of the Si (111) and (220) reflections in the work presented here. The peak intensity of the rocking curve with this configuration was approximately 2.5 x 105 neutrons per second over a 5 cm2 area of sample at 1.5 Å. The rocking curve wings fell sharply (approximately as Q"11), permitting accurate scattered intensity measurements down to a minimum Q value of 0.005 1/Å at a Q resolution of 0.003 1/Å. The technique also offers the possibility of variable resolution without too much difficulty; changes up to a factor of 2 can be made by adjusting the sample-to-analyzer crystal distance, while changes of a factor of 10 can be made by using different Si reflections. Since the incident neutron wavelength can be tuned to the peak of the leakage spectrum, this technique is ideal for low-flux reactors, which otherwise cannot be used for SANS research. The usefulness of one-dimensional SANS is demonstrated by measurements of Portland cement.

Observation of the scalar Aharonov-Bohm effect by neutron interferometry.

A phase shift for de Broglie waves due to the action of a scalar potential in an otherwise field-free (i.e., force-free) region of space is known as the scalar Aharonov-Bohm (AB) effect. Unlike the more familiar AB effect due to the magnetic vector potential, the scalar effect has hitherto remained unverified due, presumably, to technical difficulties in electron interferometry. We have performed an analogous interferometric experiment with thermal neutrons subject to pulsed magnetic fields. The observations were carried out at the University of Missouri Research Reactor using a skew-symmetric perfect-silicon-crystal neutron interferometer. The expected phase shifts have been observed to a high degree of accuracy. A detailed description of the experiment and its interpretation is given in this paper.

INAA of coals from the Midwestern USA

The concentrations of 43 elements were determined in coal samples collected from the state of Missouri using INAA at the University of Missouri Research Reactor. The results of the whole coal analysis reveal that the chemical compositions of Missouri coals are highly variable. Enrichment factors were determined for each of the elements determined in this project to provide a measure of the relative enrichment of the element as compared to the average crustal abundance for that element

Neutron Powder Diffraction Applications at the University of Missouri Research Reactor

AbstractA neutron powder diffractometer at the University of Missouri Research Reactor (MURR) uses a linear position sensitive detector (PSD) which has increased both resolution and data acquisition rates. Rietveld analysis works as well with this system as with more conventional single and multi- Soller slit detector systems. This analysis has been successfully applied to problems involving more than 75 parameters and 1200 reflections and a future instrument upgrade should allow analyses which involve 100-150 parameters. A special advantage of the PSD instrument is that it needs only small (1-2 gm) samples to achieve high statistical accuracy.

A position-sensitive detector for neutron powder diffraction

A linear position-sensitive detector has been constructed with an array of three proportional counters and installed on the neutron powder diffractometer at the University of Missouri Research Reactor. The event position is determined by the charge division method using digital arithmetic. Consideration has been given to the corrections necessary to account for the differences in detection efficiency, solid angle, dead time and resolution for different points along the detector, caused by the finite thickness and tangential orientation of the detectors. An important feature of the instrument is an oscillating radial collimator with high transmission placed between the sample and detector which enables the system to have low background and a high signal-to-noise ratio. By considering the angular rate of accumulating data, the peak intensity per channel and the resolution of a Bragg diffraction peak, the enchancement factor for the position-sensitive detector is estimated to be about 50 compared to a single detector with a step scan. This allows experiments to be performed with better statistics, better resolution and smaller samples, and enables marginal experiments to be worthwhile. A number of structures have been refined with this detector using Rietveld analysis including a new rare-earth-transition-metal phase whose structure has been solved from the powder diffraction data.

Measurement and Detection of Radiation

"Measurement and Detection of Radiation." Nuclear Technology, 67(1), pp. 182–183 Additional informationNotes on contributorsGerald A. SchlapperAfter receiving his MS in nuclear engineering from the University of Missouri at Columbia in 1970, Gerald Schlapper joined the reactor operations staff of the University of Missouri Research Reactor Facility. During this time he served for five years as a reactor physicist and was responsible for core design and burnup calculations. Dr. Schlapper received his PhD in 1977 and remained on the staff of the Research Reactor Facility until January 1981, when he assumed his current position as a faculty member of the nuclear engineering department at Texas A&M University. During his career he has served as a consultant to various government and private organizations.