9 results on '"Kotsubo, V."'
Search Results
2. Ultra-High-Resolution Alpha Spectrometry for Nuclear Forensics and Safeguards Applications.
- Author
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Bacrania, M. K., Croce, M. P., Bond, E. M., Dry, D. E., Moody, W. A., LaMont, S. P., Rabin, M. W., Rim, J. H., Smith, A. A., Beall, J. A., Bennett, D. A., Hilton, G. C., Horansky, R. D., Kotsubo, V., Ullom, J. N., and Cantor, R.
- Subjects
DETECTORS ,SPECTROMETRY ,ALPHA rays ,CALORIMETERS ,ACTINIDE elements ,RADIOACTIVE source strength - Abstract
We will present our work on the development of ultra-high-resolution detectors for alpha particle spectrometry. These detectors, based on superconducting transition-edge sensors, offer energy resolution that is five to ten times better than conventional silicon detectors. Using these microcalorimeter detectors, the isotopic composition of mixed-actinide samples can be determined rapidly without the need for actinide separation chemistry to isolate each element, or mass spectrometry to separate isotopic signatures that can not be resolved using traditional alpha spectrometry (e.g. Pu-239/Pu-240, or Pu-238/Am-241). This paper will cover the detector and measurement system, actinide source preparation, and the quantitative isotopic analysis of a number of forensics- and safeguards-relevant radioactive sources. [ABSTRACT FROM AUTHOR]
- Published
- 2010
3. Cryogenic Microcalorimeter System for Ultra-High Resolution Alpha-Particle Spectrometry.
- Author
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Croce, M. P., Bacrania, M. K., Hoover, A. S., Rabin, M. W., Hoteling, N. J., LaMont, S. P., Plionis, A. A., Dry, D. E., Ullom, J. N., Bennett, D. A., Horansky, R. D., Kotsubo, V., and Cantor, R.
- Subjects
CALORIMETERS ,ALPHA ray spectrometry ,DETECTORS ,LIQUID nitrogen ,CRYOSTATS - Abstract
Microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrometry, up to 1.06 keV FWHM at 5.3 MeV. These detectors use a superconducting transition-edge sensor (TES) to measure the temperature change in an absorber from energy deposited by an interacting alpha particle. Our system has four independent detectors mounted inside a liquid nitrogen/liquid helium cryostat. An adiabatic demagnetization refrigerator (ADR) cools the detector stage to its operating temperature of 80 mK. Temperature regulation with ∼15-μK peak-to-peak variation is achieved by PID control of the ADR. The detectors are voltage-biased, and the current signal is amplified by a commercial SQUID readout system and digitized for further analysis. This paper will discuss design and operation of our microcalorimeter alpha-particle spectrometer, and will show recent results. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
4. Integration of Radioactive Material with Microcalorimeter Detectors.
- Author
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Croce, M., Bond, E., Hoover, A., Kunde, G., Moody, W., Rabin, M., Bennett, D., Hayes-Wehle, J., Kotsubo, V., Schmidt, D., and Ullom, J.
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RADIOACTIVE tracers ,CALORIMETERS ,NUCLEAR energy ,NEUTRINO mass ,NEUTRINO detectors ,ACTINIDE elements - Abstract
Microcalorimeter detectors with embedded radioactive material offer many possibilities for new types of measurements and applications. We will discuss the designs and methods that we are developing for precise deposition of radioactive material and its encapsulation in the absorber of transition-edge sensor (TES) microcalorimeter detectors for two specific applications. The first application is total nuclear reaction energy (Q) spectroscopy for nuclear forensics measurements of trace actinide samples, where the goal is determination of ratios of isotopes with Q values in the range of 5-7 MeV. Simplified, rapid sample preparation and detector assembly is necessary for practical measurements, while maintaining good energy resolution. The second application is electron capture spectroscopy of isotopes with low Q values, such as $$^{163}$$ Ho, for measurement of neutrino mass. Detectors for electron capture spectroscopy are designed for measuring energies up to approximately 6 keV. Their smaller heat capacity and physical size present unique challenges. Both applications require precise deposition of radioactive material and encapsulation in an absorber with optimized thermal properties and coupling to the TES. We have made detectors for both applications with a variety of designs and assembly methods, and will present their development. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
5. Ultra-high Resolution Alpha Particle Spectrometry with Transition-Edge Sensor Microcalorimeters.
- Author
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Croce, M., Bacrania, M., Bond, E., Dry, D., Moody, W., Rabin, M., Bennett, D., Hilton, G., Horansky, R., Kotsubo, V., Schmidt, D., Ullom, J., Vale, L., and Cantor, R.
- Subjects
SILICON diodes ,CALORIMETERS ,ENVIRONMENTAL monitoring ,RADIOISOTOPES ,NUCLEAR energy ,RADIOCHEMISTRY ,MECHANICAL loads - Abstract
Alpha particle spectrometry is a powerful analytical tool for nuclear forensics and environmental monitoring. Microcalorimeter detectors have been shown to yield nearly an order of magnitude better energy resolution (1.06 keV FWHM at 5.3 MeV) than current state-of-the-art silicon detectors (8-10 keV FWHM at 5.3 MeV). This superior resolution allows isotopic analysis with a single non-consumptive measurement of samples that contain multiple radioisotopes with overlapping alpha energies. Measurement of such a sample with a silicon detector would require expensive and time-consuming radiochemical separations. We are developing two alpha spectrometer systems with superconducting transition-edge sensor microcalorimeters. The first system has eight independent detector channels that measure eight different alpha sources, and is optimized for detector development experiments. The second system incorporates a prototype cryogenic load lock that allows for rapid exchange of alpha samples. This paper will present results from these two systems. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
6. Dedicated Co-deposition System for Metallic Paramagnetic Films.
- Author
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Jaeckel, F., Kotsubo, V., Hall, J., Cantor, R., and Boyd, S.
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CALORIMETERS , *PARAMAGNETISM , *SPUTTERING (Physics) , *THIN films , *MAGNETIC devices , *ALLOYS , *DOPING agents (Chemistry) - Abstract
We describe a dedicated co-sputtering/ion-mill system developed to study metallic paramagnetic films for use in magnetic microcalorimetry. Small-diameter sputtering guns allow study of several precious-metal paramagnetic alloy systems within a reasonable budget. We demonstrated safe operation of a 1″ sputtering gun at greater than five times the rated maximum power, achieving deposition rates up to ∼ 900 Å/min/gun (Cu) in our co-sputtering geometry. Demonstrated co-sputtering deposition ratios up to 100:1 allow accurate tuning of magnetic dopant concentration and eliminate the difficulty of preparing homogeneous alloy targets of extreme dilution. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
7. Superconducting Transition-Edge Sensor Microcalorimeters for Ultra-High Resolution Alpha-Particle Spectrometry.
- Author
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Croce, M. P., Bacrania, M. K., Bond, E. M., Dry, D. E., Klingensmith, A. L., Moody, W. A., LaMont, S. P., Rabin, M. W., Rim, J. H., Beall, J. A., Bennett, D. A., Kotsubo, V., Horansky, R. D., Hilton, G. C., Schmidt, D., Ullom, J. N., and Cantor, R.
- Subjects
CALORIMETERS ,ALPHA rays ,SILICON diodes ,RADIOISOTOPES ,SEMICONDUCTORS ,ENERGY conservation ,ELECTRONS - Abstract
Alpha-particle spectrometry is a powerful analytical tool for nuclear forensics and environmental monitoring. Superconducting transition-edge sensor microcalorimeters have been shown to yield unsurpassed energy resolution for alpha spectrometry. With nearly an order of magnitude better energy resolution (1.06 keV FWHM at 5.3 MeV) than the current state-of-the-art silicon detectors (8–10 keV at 5.3 MeV), it is possible to measure samples containing multiple radioisotopes that would require expensive and time-consuming radiochemical separation prior to measurement with a silicon detector. This paper presents recent results from the Los Alamos four-channel microcalorimeter alpha spectrometer. We have prepared a source from weapons-grade plutonium and demonstrated the ability of microcalorimeter alpha spectrometry to simultaneously resolve alpha energies from ^239Pu, ^240Pu, ^238Pu, and ^241Am. The low-energy performance of the spectrometer system has been improved to allow measurement of energies as low as 5 keV, which gives a dynamic range of 1000. We have demonstrated this capability by simultaneously measuring the alpha particles and low-energy x-rays and internal conversion electrons emitted by an electroplated ^240Pu source. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
8. A high resolution gamma-ray spectrometer based on superconducting microcalorimeters.
- Author
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Bennett, D. A., Horansky, R. D., Schmidt, D. R., Hoover, A. S., Winkler, R., Alpert, B. K., Beall, J. A., Doriese, W. B., Fowler, J. W., Fitzgerald, C. P., Hilton, G. C., Irwin, K. D., Kotsubo, V., Mates, J. A. B., O'Neil, G. C., Rabin, M. W., Reintsema, C. D., Schima, F. J., Swetz, D. S., and Vale, L. R.
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GAMMA rays ,SPECTROMETERS ,SUPERCONDUCTING cables ,CALORIMETERS ,SUPERCONDUCTING quantum interference devices ,ELECTRONIC data processing - Abstract
Improvements in superconductor device fabrication, detector hybridization techniques, and superconducting quantum interference device readout have made square-centimeter-sized arrays of gamma-ray microcalorimeters, based on transition-edge sensors (TESs), possible. At these collecting areas, gamma microcalorimeters can utilize their unprecedented energy resolution to perform spectroscopy in a number of applications that are limited by closely-spaced spectral peaks, for example, the nondestructive analysis of nuclear materials. We have built a 256 pixel spectrometer with an average full-width-at-half-maximum energy resolution of 53 eV at 97 keV, a useable dynamic range above 400 keV, and a collecting area of 5 cm2. We have demonstrated multiplexed readout of the full 256 pixel array with 236 of the pixels (91%) giving spectroscopic data. This is the largest multiplexed array of TES microcalorimeters to date. This paper will review the spectrometer, highlighting the instrument design, detector fabrication, readout, operation of the instrument, and data processing. Further, we describe the characterization and performance of the newest 256 pixel array. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
9. Large microcalorimeter arrays for high-resolution X- and gamma-rayspectroscopy
- Author
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Hoover, A.S., Hoteling, N., Rabin, M.W., Ullom, J.N., Bennett, D.A., Karpius, P.J., Vo, D.T., Doriese, W.B., Hilton, G.C., Horansky, R.D., Irwin, K.D., Kotsubo, V., Lee, D.W., and Vale, L.R.
- Subjects
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GAMMA ray spectrometry , *CALORIMETERS , *PLUTONIUM , *GERMANIUM diodes , *PERFORMANCE evaluation , *NUCLEAR matter - Abstract
Abstract: Microcalorimeter detectors provide unprecedented energy resolution for the measurement of X-rays and soft gamma-rays. Energy resolution in the 100keV region can be up to an order of magnitude better than planar high-purity germanium (HPGe) detectors. The technology is well-suited to analysis of materials with complex spectra presenting closely spaced photopeaks. One application area is the measurement and assay of nuclear materials for safeguards and fuel cycle applications. In this paper, we discuss the operation and performance of a 256-pixel array, and present results of a head-to-head comparison of isotopic determination measurements with high-purity germanium using a plutonium standard. We show that the uncertainty of a single measurement is smaller for the microcalorimeter data compared to the HPGe data when photopeak areas are equal. We identify several key areas where analysis codes can be optimized that will likely lead to improvement in the microcalorimeter performance. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
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