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1.
K. Ünlü C. Rios-Martinez B. W. Wehring 《Journal of Radioanalytical and Nuclear Chemistry》1995,193(1):145-154
A Prompt Gamma Activation Analysis (PGAA) facility is being developed at The University of Texas at Austin (UT). The UT-PGAA facility will utilize a focused cold-neutron beam from the Texas Cold Neutron Source (TCNS). the TCNS consists of a cold source cryostat and a curved neutron guide. the use of a guided focused cold-neutron beam will provide a high capture reaction rate and low background. The UT-PGAA facility will be used in the nondestructive determination of B, Cd, Gd and S in biological and environmental samples. 相似文献
2.
C. Ríos-Martínez K. Ünlü B. W. Wehring 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):119-124
The University of Texas cold-neutron prompt gamma-activation analysis (PGAA) facility is operational at the 1-MW UT TRIGA
research reactor. The UT-PGAA facility utilizes a guided cold neutron beam produced by the Texas Cold Neutron Source. The
cold neutrons are transported to the PGAA chamber via a 6-m long curved neutron guide followed by an 80-cm long converging
neutron guide. A program of testing, optimizing, and calibrating the UT-PGAA facility is currently underway. Preliminary results
for the sensitivities and detection limits of boron, hydrogen, and silicon in semiconductor materials are given. 相似文献
3.
Summary The PGAA applications can be enhanced by using subthermal neutrons, cold neutrons at university research reactors. Only two cold neutron beam facilities were developed at the U.S. university research reactors, namely at Cornell University and the University of Texas at Austin. Both facilities used mesitylene moderator. The mesitylene moderator in the Cornell Cold Neutron Beam Facility (CNBF) was cooled by a helium cryorefrigerator via copper cold fingers to maintain the moderator below 30 K at full power reactor operation. Texas Cold Neutron Source (TCNS) also uses mesitylene moderator that is cooled by a cryorefrigerator via a neon thermosiphon. The operation of the TCNS is based on a helium cryorefrigerator, which liquefies neon gas in a 3-m long thermosiphon. The thermosiphon cools and maintains mesitylene moderator at about 30 K in a chamber. Neutrons streaming through the mesitylene chamber are moderated and thus reduce their energy to produce a cold neutron distribution. 相似文献
4.
A fast pneumatic transfer facility was installed in Nuclear Engineering Teaching Laboratory (NETL) of the University of Texas
at Austin for the purpose of cyclic thermal and epithermal neutron activation analysis. In this study efforts were focused
on the evaluation of cyclic epithermal neutron activation analysis (CENAA). Various NIST and CANMET certified materials were
analyzed by the system. Experiment results showed 110Ag with its 25 s half-life as one of the isotopes favored by the system. Thus, the system was put into practical application
in identifying silver in metallic ores. Comparison of sliver concentrations as determined by CENAA in CANMET certified reference
materials gave very good results. 相似文献
5.
6.
S. Landsberger A. Plionis S. Biegalski K. Foltz-Biegalski E. Schneider D. J. O’Kelly J. Braisted S. O’Kelly L. Welch 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):863-866
Over the last three years we have developed a very robust nuclear and radiochemistry program at The University of Texas at
Austin. The cornerstone of support was the DOE Radiochemistry Educational Award Program (REAP) that was awarded from 2002–2005.
A second award for the period of 2005–2008 was just received. This award has enabled us to support many educational activities
from vanguard classroom instruction, to laboratory enhancements, to research activities at the graduate and undergraduate
levels. Both traditional radiochemistry and advanced topics in nuclear instrumentation have been supported. Various DOE university
programs, national lab funding and IAEA fellowship grants, have allowed the Nuclear and Radiation Engineering Program at the
University of Texas to be at the forefront of nuclear and radiochemistry educational and research activities and help secure
the next generation of needed expertise. 相似文献
7.
Carlos A. Rios Perez Justin D. Lowrey Steven Biegalski Mark R. Deinert 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):261-265
Developing a better understanding of xenon transport through porous systems is critical to predicting how this gas will enter
the atmosphere after a below ground nuclear weapons test. Radioxenon monitoring is a vital part of the Comprehensive Nuclear-Test-Ban
Treaty (CTBT) International Monitoring System. This work details the development of prompt gamma activation analysis for measuring
the diffusion rates of xenon and argon gases through a porous medium. The University of Texas at Austin maintains a prompt
gamma activation analysis facility with a peak neutron flux of ~1.5 × 107 cm−2 s−1 and a beam diameter of 1 cm. Due to the relatively large prompt gamma cross sections of many stable xenon isotopes at thermal
and sub-thermal neutron energies, prompt gamma activation analysis is a suitable technique for in situ non-destructive analysis
of natural xenon. A test chamber has been designed and constructed to utilize prompt gamma activation analysis to measure
xenon and argon diffusion through geological materials (e.g., sand, soil, etc.). Initial experiments have been conducted to determine the detection limits for stable gas measurements.
The results from these experiments will be utilized to benchmark parts of a xenon transport model that is being used to determine
diffusion coefficients for xenon and argon. 相似文献
8.
Over the last six years through a Department of Energy Radiochemistry Education Award Program (REAP) we have developed a completely
web-based course in nuclear and radiochemistry given at the University of Texas at Austin. This course has had nuclear and
radiation engineering and chemistry graduate students. While the course also has an extensive laboratory component only the
lectures are web based. The lectures begin with a historical introduction of radiochemistry followed by two movies on Madame
Curie. This is followed by the usual lectures on radioactivity, fundamental properties, radioactive decay, decay modes, and
nuclear reactions. As section on radioactive waste management and nuclear fuel cycle is also presented. Lectures in neutron
activation analysis, geo- and cosmochemistry, and plutonium chemistry have also been developed. All lectures are in power
point with many animations and a significant number of solved problems. All students are required to make a short oral presentation
on some aspect of nuclear and radiochemistry in their research or a chosen topic. 相似文献
9.
S. M. Whitney S. R. F. Biegalski G. Downing 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):173-176
The University of Texas at Austin Neutron Depth Profiling (UT-NDP) facility was utilized to analyze varying cathode compositions in lithium battery materials. Battery materials included LiCoO2, LiMn1/3Ni1/3Co1/3O2, and LiFePO4. The cells were made at The University of Texas at Austin as coin cells with lithium anodes. The NDP analysis method for Li in battery materials was benchmarked between two facilities and with computational models. 相似文献
10.
S. Landsberger T. Tipping O. Ezekoye D. Tamalis V. Lott S. Alexander G. Ban 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):59-61
Neutron activation analysis (NAA) remains an excellent technique to introduce undergraduate students to nuclear science and
engineering coming from different academic areas. The NAA methods encompass an appreciation of basic reactor engineering concepts,
radiation safety, nuclear instrumentation and data analysis. At the Nuclear Engineering Teaching Lab at the University of
Texas at Austin we have continued to provide opportunities through outreach programs to Huston-Tillotson University in Austin
and Florida Memorial University in Miami Gardens, both Historically Black Colleges and Universities, and Southwestern University
in Georgetown, Texas. Furthermore, in the past four years we have established a strong educational collaboration with the
école Nationale Supérieure d’Ingénieurs de Caen (ENSICAEN), France. Undergraduate students at ENSICAEN are required to have
an internship outside of France. While many of the students stay in neighboring European countries others have chosen the
United States. The cornerstone of these programs is to secure a relationship with each institution through clear educational
and research objectives and goals. 相似文献
11.
Danyal Turkoglu Joshua Burke Radoslaw Lewandowski Lei R. Cao 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):321-327
A thermal neutron beam facility has been designed and implemented at the Ohio State University Research Reactor. A project
is underway to construct a large vacuum chamber such that the facility could have neutron depth profiling and neutron radiography
capabilities as intended. The neutron beam is extracted from the reactor through a neutron collimator emplaced in Beam Port
#2. The neutron spectrum entering the neutron collimator was unfolded from foil activation analysis results and also simulated
with a full reactor core model in the MCNP Monte Carlo code. The neutron collimator uses polycrystalline bismuth as a gamma
ray filter and single-crystal sapphire as a fast neutron filter. The beam is defined by multiple 3.0 cm diameter apertures
made of borated aluminum. Characterization of the beam was performed using foil activation to find the flux and a low-budget
neutron imaging apparatus to see the beam profile. The modulation transfer function was calculated to offer insight into the
resolution of the imaging system and the collimation of the beam. The neutron collimator delivers the filtered thermal neutron
beam with a ~4 cm diameter and a thermal equivalent flux of (1.27 ± 0.03) × 107 n/(cm2s) at 450 kW power at the end of the collimator. 相似文献
12.
Joseph Graham Stephen Biegalski Bruce Bucholtz 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):233-236
Field measurement of isotopic ratios may be used to fingerprint an element’s origin, be it from commercial power, industrial, medical or historical weapons fallout. Samples of samarium radionuclides were prepared by neutron activation for subsequent analysis using accelerator mass spectrometry (AMS). High purity samarium (III) oxide powder was irradiated in the University of Texas at Austin TRIGA reactor to a total neutron fluence of 5 × 1015 cm?2. An initial determination of the isotopic ratios was made using activation calculations with a BURN card in an MCNPX-based model of the TRIGA core. Experimental validation of the MCNP results was achieved by analyzing gamma spectra of the irradiated oxide powers after irradiation. Subsequent measurement of 151Sm will be conducted at the CAMS facility at LLNL demonstrating the first measurement of this isotope at this facility. 相似文献
13.
The neutron depth profiling (NDP) technique has become an increasingly important method to nondestructively measure the absolute concentration versus depth of various elements in substrates. A permanent NDP facility is operational at a tangential beam port of the 1-MW TRIGA Mark II research reactor at The University of Texas at Austin (UT). This facility was developed to perform materials research, specifically measurements of interest to the microelectronics industry. Applications of the UT-NDP facility include measurements of boron-10 profiles in borophosphosilicate glass samples and helium-3 depth profiles of implanted helium-3 in metals, alloys and amorphous materials. A study is underway to determine radiation damage and microstructural changes in stainless steel samples by helium irradiation using NDP and Transmission Electron Microscopy. Another study, currently planned, is to measure surface wear by measuring the depth profiles of implanted beryllium-7 and sodium-22 in various materials. 相似文献
14.
Bangfa Ni Caijing Xiao Donghui Huang Hongchao Sun Guiying Zhang Cunxiong Liu Pingsheng Wang Haiqing Zhang Weizhi Tian 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):313-319
China Advance Research Reactor (CARR) at China Institute of Atomic Energy (CIAE), with a non-perturbed maximum thermal neutron
flux of 1 × 1015 cm−2 s−1 at the center of active area, is one of the most powerful research reactors in the world. Three neutron channels have been
allocated for conventional neutron activation analysis (NAA), thermal neutron prompt gamma activation analysis (PGAA) and
cold neutron PGAA, respectively. Two irradiation tube systems are installed in the conventional NAA channel. One of them is
for short irradiation with the rabbit size of diameter (Φ)19 × 40 mm, the other one is for long irradiation with the rabbit
size of Φ39 × 70 mm. The medium temperature is about 45 °C and the thermal neutron flux is about 3 × 1014 cm−2 s−1 at sample positions. The flux gradient is expected to be very small according to the designed neutron flux distribution.
Pneumatic systems are used for samples transfer. The speed of rabbits is designed to be about 20 m/s, and it takes 3 s to
travel from irradiation position to detector. Three sets of gamma counting systems and one delayed neutron counting system
are being equipped for routine analysis. They are designed for running continuously and automatically. And all the functions
can be operated at laboratory or office through remote controlled computer. Software has been made domestically for spectrum
peak search, concentration calculation with relative method and k0 method with interference corrections and some other functions for the convenience of users. 相似文献
15.
Zs. Révay T. Belgya L. Szentmiklósi Z. Kis 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):643-646
The PGAA facility at the Budapest Research Reactor has been continually upgraded and developed since its start-up in 1996,
as a result of which its performance has improved considerably. The installation of the cold neutron source, the partial change
to supermirror neutron guides and their realignment increased the flux by almost two orders of magnitude. The data acquisition
has been modernized as well; digital spectrometers were tested and implemented in novel forms of gamma-ray spectrum collection.
This year a higher-efficiency HPGe detector and a new data acquisition module were put into operation. Most recently all the
neutron guides were changed to supermirror-coated ones to further increase the neutron flux. The improved evaluation software
makes possible a more reliable elemental analysis of the samples. In this progress report these developments are critically
reviewed. The characteristics of the latest system are also described. It is the first time that a set of new partial gamma-ray
production cross sections are presented, which are based on the new intensity values of 14N(n,γ)15N calibration standard. 相似文献
16.
L. R. Cao J. R. Hattrick-Simpers R. Bindel B. E. Tomlin R. Zeisler R. Paul L. A. Bendersky R. G. Downing 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):63-68
Cold neutron prompt gamma activation analysis (PGAA) was used to determine the mass of hydrogen in Mg hydride thin films with
varying hydrogenation times. The results suggest that hydrogenation of the Mg thin films remains unsaturated even after 48 h
of treatment, contrary to the indications of inferential hydrogen measurement methods. To demonstrate PGAA as an effective
combinatorial methodology for hydride thin films, a continuously varying composition gradient of thin MgyTi(1−y) hydride film with y ranging from 0.65 to 0.94 was prepared and analyzed by both PGAA and instrumental neutron activation
analysis (INAA). The variation in the molar ratio of Mg, Ti, and H was obtained for nine 5 mm wide segments of the film. 相似文献
17.
R. L. Paul R. M. Lindstrom C. Brocker E. A. Mackey 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):697-701
A new instrument for cold neutron prompt gamma-ray activation analysis (CNPGAA) is being designed and constructed at the NIST
Center for Neutron Research (NCNR). The new instrument is expected to have lower gamma-ray and neutron background and better
detection limits for most elements than the current cold neutron PGAA instrument. Other advantages over the current facility
will include the ability to analyze larger samples and greater overall measurement capability due to the addition of scanning
stages, cryostats, and sample changers. 相似文献
18.
S. M. Whitney R. G. Downing S. Biegalski D. S. O’Kelly 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):257-261
The University of Texas (UT) at Austin has collaborated with the National Institute of Standards and Technology for comparisons
of concentration versus depth profiles of samples containing 10B. Technology sharing from NIST has allowed UT to avoid many initial set backs such that significant advancements in the UT-NDP
facility’s experimental and analytical methodology have been achieved. UT has analyzed two samples loaned to them from NIST.
The collaborative effort between the two institutions has given the UT-NDP facility the proper tools to begin profiling more
advanced samples in hopes of meeting the capabilities set by NIST in the NDP field. The UT-NDP facility was able to profile
a borosilicate surface deposit onto silicon such that the concentrations of 10B at various depths of the deposit were determined and fit well to a Pearson distribution. 相似文献
19.
C. S. Park G. M. Sun S. H. Byun H. D. Choi 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(2):283-286
Summary The new PGAA facility using diffracted neutron beam was developed in Korea. The basic characteristics of the facility were studied in detail. A general formalism of the k0 factor as extended to non-1/v absorber and arbitrary neutron spectrum was discussed and the actual data for Cd, Sm, Eu, Gd have been measured and determined successfully owing to the simple nature of the diffracted neutron spectrum. The k0 factors for B, N, Si, P, S and Cl were also determined and showed consistent results with previously reported ones. At an early stage, feasibility of boron concentration analysis and measurement of thermal neutron capture cross sections has been studied. The PGAA facility is now open to users. A considerable amount of beam time is already dedicated to studies on the elemental analysis. 相似文献
20.
P. Kudějová Th. Materna J. Jolie A. Türler P. Wilk S. Baechler Zs. Kasztovszky Zs. Révay T. Belgya 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(2):221-227
Summary A new flexible prompt gamma-ray activation analysis (PGAA) station will be installed and operated at the FRM-II reactor in Garching at the beginning of the year 2006. The PGAA station has been moved from the Paul Scherrer Institute (PSI), Villigen, Switzerland and is now being re-designed for three different experimental applications: PGAA instrument, cold neutron tomography setup and a compact Ge-array. Simulations of the beam guide have been carried out in order to yield the best conditions for each of the instruments, and are discussed here. A number of the PGAA applications are listed here. A new project dealing with a systematic measurement of bulky composition of small amount of meteorites (~100 mg) is proposed. Results of a test measurement of the Dhurmasala meteorite composition at the PGAA station at the Budapest Research Reactor are presented. Expected parameters of the PGAA facility at FRM-II are compared both with those at PSI and with the Budapest facility. 相似文献