S.M.A.R.T. Lab - Reports, Patents and Publications

Reports

SMART LABORATORY REPORTS

2007 Annual Report

DOE GRANTS

2006 DOE NEER Final Report

2006 DOE NERI Final Report

2004 DOE NEER Final Report

2002 DOE NEER Final Report

2002 DOE SBIR Final Report

Patents

US 6175120: High Resolution Ionization Detectors and Array of Such Detectors

US 6479826: Coated Semiconductor Devices for Neutron Detection

US 6528797: Method and System for Determining Depth Distribution of Radiation-Emitting Materials Located in a Source Medium and Radiation Detection System for Use Therein

US 6545281: Pocked Surface Neutron Detector

US 6570165: Radiation Assisted Electron Emission Source

US 6727505: Method and System for Determining Depth Distribution of Radiation-Emitting Materials Located in a Source Medium and Radiation Detection System for Use Therein

US 6781132: Collimated Radiation Detector Assembly, Array of Collimated Radiation Detectors and Collimated Radiation Detector Module

US 6806474: Method and System for Detecting Ionizing Radiation

US 6815687: Method and System for High-Speed, 3D Imaging of Optically-Invisible Radiation

US 6921903: Method and System for Measuring Neutron Emissions and Ionizing Radiation

US 7164138: High-Efficiency Neutron Detectors and Methods of Making the Same

Publications

REFEREED PUBLICATIONS

M.J. Harrison, A. Kargar, D.S. McGregor, "Improved Fabrication of Frisch Collar CdZnTe Gamma Ray Spectrometers," IEEE Trans. Nucl. Sci., (2008) submitted.

M. F. Ohmes, J. K. Shultis, D. S. McGregor, "3D Real-Time in-Core Neutron Flux Mapping with Micro-Pocket Fission Detectors (MPFD)," IEEE Trans. Nucl. Sci., (2008) submitted.

D.S. McGregor, T.C. Unruh, and W.J. McNeil, "Thermal Neutron Detection with Pyrolytic Boron Nitride," Nucl. Instrum. and Meth. A, (2008) in press.

M.J. Harrison, F.P. Doty, D.S. McGregor, "The Fano Factor and Non-Uniformities Affecting Charge Transport in Semiconductors," Phys. Rev. B, (2008) in press.

D.S. McGregor, S. Bellinger, D. Bruno, W.L. Dunn, W.J. McNeil, E. Patterson, B.B. Rice, J.K. Shultis, T. Unruh, "Perforated Diode Neutron Detector Modules Fabricated from High-Purity Silicon," Radiation Physics and Chemistry, (2008) in press.

Q. Jahan, E. Patterson, B. Rice, W.L. Dunn and D.S. McGregor, "Neutron Dosimeters Employing High-efficiency Perforated Semiconductor Detectors," Nuc. Instrum. and Meth. B, 263 (2007) pp. 183-185.

K.C. Mandal, S.H. Kang, M. Choi, A.Kargar, M.J. Harrison, D.S. McGregor, A.E. Bolotnikov, G.A. Carini, G.C. Camarda, R.B. James, "Characterization of Low Defect Cd_0.9Zn_0.1Te and CdTe Crystals for High Performance Frisch Collar Detectors," IEEE Trans. Nucl. Sci, NS-54 (2007) pp. 802-806.

C.J. Solomon, J.K. Shultis, W.J. McNeil, T.C. Unruh, B.B. Rice, and D.S. McGregor, "A Hybrid Method for Coupled Neutron-Ion Transport Calculations for ¹⁰B and ⁶LiF Coated and Perforated Detector Efficiencies," Nucl. Instrum. and Meth. A, A580 (2007) pp. 326-330.

Y. Cui, A. E. Bolotnikov, G. S. Camarda, G. De Geronimo, P. O'Connor, R. B. James, A. Kargar, M. J. Harrison, and D. S. McGregor, "Readout System for Arrays of Frisch-ring CdZnTe Detectors," IEEE Trans. Nuclear Science, NS-54 (2007) pp. 849-853.

A.S.M. Sabbir Ahmed, J.K. Shultis and D.S. McGregor, "Response Functions for Calculating Density Profiles in Fuel Rods Using In-Core Neutron Detectors," Prog. In Nucl. Energy, 49 (2007) pp. 385-396.

M.J. Harrison, A. Kargar, D.S. McGregor, "Charge Collection Characteristics of Frisch Collar CdZnTe Gamma Ray Spectrometers," Nucl. Instrum. and Meth. A, A579 (2006) pp. 134-137.

M.F. Ohmes, D. S. McGregor, J. K. Shultis, A.S.M.S. Ahmed, R. Ortiz, R.W. Olsen, "Recent Results and Fabrication of Micro-Pocket Fission Detectors (MPFD)," Proc. SPIE, Vol. 6319 (2006) pp. 1P1-1P9.

J.K. Shultis and D.S. McGregor, "Efficiencies of Coated and Perforated Semiconductor Neutron Detectors," IEEE Trans. Nuclear Science, NS-53 (2006) pp. 1659-1665.

A. Kargar, A.M. Jones, W.J. McNeil, M.J. Harrison, and D.S. McGregor, "Angular Response of a W-Collimated Room-Temperature-Operated CdZnTe Frisch Collar Spectrometer," Nuclear Instrum. and Meth., A562 (2006) pp. 262-271.

A.E. Bolotnikov, G.S. Camarda, G.A. Carini, M. Fiederle, D.S. McGregor, W. McNeil, G.W. Wright, and R. B. James, "Performance Characteristics of Frisch-Grid CdZnTe Detectors," IEEE Trans. Nuclear Science, vol. NS-53 (2006) pp. 607-614.

M. J. Harrison, A.P. Graebner, W.J. McNeil, and D.S. McGregor, "Carbon-Coating of Fused Silica Ampoules," Journal of Crystal Growth, 290 (2006) pp. 597-601.

A. Kargar, A.M. Jones, W.J. McNeil, M.J. Harrison and D.S. McGregor, "CdZnTe Frisch Ring Detectors for Gamma Ray Spectroscopy," Nuclear Instrum. and Meth., A558 (2006) pp. 497-503.

D.S. McGregor, M.F. Ohmes, R.E. Ortiz, A.S.M.S. Ahmed, and J.K. Shultis, "Micro-Pocket Fission Detectors (MPFD) for In-Core Neutron Flux Monitoring," Nucl. Instrum. and Meth., A554 (2005) 494-499.

D.S. McGregor and J.K. Shultis, "Response to Comment by Hallbeck et al.," Nuclear Instruments and Methods, A536 (2005) pp. 232-234.

A.E. Bolotnikov, G. S. Camarda, G. A. Carini, G. W. Wright, R. B. James, D. S. McGregor, and W. McNeil, "New Results from Performance Studies of Frisch-Grid CdZnTe Detectors," Proc. SPIE, Vol. 5540 (2004) pp. 33-45.

W. J. McNeil, D. S. McGregor, A. E. Bolotnikov, G. W. Wright, R.B. James, "Single Charge Carrier Type Sensing with an Insulated Frisch Ring CdZnTe Semiconductor Radiation Detector," Applied Physics Letters, 84 (2004) pp. 1988-1990.

D. S. McGregor and J. K. Shultis, "Spectral Identification of Thin-Film-Coated and Solid-Form Semiconductor Neutron Detectors," Nuclear Instruments and Methods, A517 (2004) pp. 180-188.

M.F. Ohmes, D. S. McGregor, J. K. Shultis, P. M. Whaley, A.S.M. Sabbir Ahmed, C. C. Bolinger, T. C. Pinsent, "Development of Micro-Pocket Fission Detectors (MPFD) for Near-Core and In-Core Neutron Flux Monitoring," Proc. SPIE, Vol. 5198 (2003) 234-242.

P.M. De Lurgio, R.T. Klann, C.L. Fink, D.S. McGregor, P. Thiyagarajan, I. Naday, "A Neutron Detector to Monitor the Intensity of Transmitted Neutrons for Small-Angle Neutron Scattering Instruments," Nuclear Instruments and Methods, A505 (2003) pp. 46-49.

D.S. McGregor, M.D. Hammig, H.K. Gersch, Y-H. Yang, and R.T. Klann, "Design Considerations for Thin Film Coated Semiconductor Thermal Neutron Detectors, Part I: Basics Regarding Alpha Particle Emitting Neutron Reactive Films," Nuclear Instruments and Methods, A500 (2003) pp. 272 - 308.

D. S. McGregor, R. T. Klann, J. D. Sanders, J.T. Lindsay, K.J. Linden, H.K. Gersch, P.M. De Lurgio, C.L. Fink, and Elsa Ariesanti, "Recent Results From Thin-Film-Coated Semiconductor Neutron Detectors," Proc. of SPIE, Vol. 4784 (2002) pp. 164-182.

D.S. McGregor, R.T. Klann, H.K. Gersch, E. Ariesanti, J.D. Sanders, and B. VanDerElzen, "New Surface Morphology for Low Stress Thin-Film-Coated Thermal Neutron Detectors," IEEE Trans. Nuclear Science, 49 (2002) pg. 1999-2004.

H.K. Gersch, D.S. McGregor, and P.A. Simpson, "A Study of the Effect of Incremental Gamma-Ray Doses and Incremental Neutron Fluences Upon the Performance of Self-Biased 10B-Coated High-Purity Epitaxial GaAs Thermal Neutron Detectors," Nuclear Instruments and Methods, A489 (2002) pp. 85-98.

D.S. McGregor, H.K. Gersch, J.D. Sanders, R.T. Klann, and J.T. Lindsay, "Thin-Film-Coated Detectors for Neutron Detection," Journal of the Korean Association for Radiation Protection, 26 (2001) pp. 167-175.

K.L. Jensen, Y.Y. Lau and D. S. McGregor, "Photon Assisted Field Emission from a Si Emitter," Solid-State Electronics, 45 (2001) pp. 831-840.

D.S. McGregor, R.T. Klann, H.K. Gersch, and Y–H. Yang, “Thin-Film-Coated Bulk GaAs Detectors for Thermal and Fast Neutron Measurements,” Nuclear Instruments and Methods, A466 (2001) pp. 126-141.

D.S. McGregor, "Rethinking Nuclear Power," The New American, Vol. 17, No. 9 (2001) pp. 10-19.

D.S. McGregor, J.R. Nishanth, and D.K. Wehe, "Low Energy Gamma-Ray Characterization of a Trapezoid-Shaped Geometrically-Weighted Frisch Grid CdZnTe Gamma-Ray Spectrometer," Nuclear Instruments and Methods, A457 (2001) pp. 230-244.

D.S. McGregor, J.R. Nishanth, and D.K. Wehe, "Design Considerations for Trapezoidal-Shaped Frisch Grid Semiconductor Radiation Detectors," Proc. of SPIE, Vol. 4141 (2000) pp. 281-290.

K.L. Jensen, Y.Y. Lau and D. S. McGregor, "Analysis of a Photon Assisted Field Emission Device" Applied Physics Letters, 77 (2000) pp.585-587.

D.S. McGregor, S.M. Vernon, H.K. Gersch, S.M. Markham, S.J. Wojtczuk and D.K. Wehe, "Self-Biased Boron-10 Coated High Purity Epitaxial GaAs Thermal Neutron Detectors," IEEE Trans. Nuclear Science, 47 (2000) pp. 1364-1370.

D.S. McGregor and R.A. Rojeski, "Performance of Geometrically Weighted Semiconductor Frisch Grid Radiation Spectrometers," IEEE Trans. Nuclear Science, 46 (1999) pp. 250-259.

D.S. McGregor, R.A. Rojeski, Z. He, D.K. Wehe, M. Driver and M. Blakeley, "Geometrically Weighted Semiconductor Frisch Grid Radiation Spectrometers," Nuclear Instruments and Methods, A422 (1999) pp. 164-168.

D.S McGregor, Z. He, H.A. Seifert, R.A. Rojeski and D.K. Wehe, "CdZnTe Semiconductor Parallel Strip Frisch Grid Radiation Detectors," IEEE Trans. Nuclear Science, 45 (1998) pp. 443-449.

D.S McGregor, Z. He, H.A. Seifert, D.K. Wehe, and R.A. Rojeski, "Single Charge Carrier Type Sensing with a Parallel Strip Pseudo-Frisch-Grid CdZnTe Semiconductor Radiation Detector," Applied Physics Letters, 72 (1998) pp. 792-794.

D.S. McGregor and H. Hermon, "Room Temperature Compound Semiconductor Radiation Detectors," Nuclear Instruments and Methods, A395 (1997) pp.101-124.

J.T. Lindsay, C.C. Brannon, D.S. McGregor, and R.W. Olsen, "A Solid State, Position Sensitive GaAs Device as a Neutron Camera," Fifth World Conference on Neutron Radiography, Berlin, Germany, June 17 – 20 (1996) pp. 240-248.

D.S. McGregor, J.T. Lindsay and R.W. Olsen, "Thermal Neutron Detection with CdZnTe Detectors," Nuclear Instruments and Methods, A381 (1996) pp. 498-501.

CONFERENCE SUBMISSIONS

W.J. McNeil, S.L. Bellinger, B.J. Blalock, C.L. Britton Jr., J.L. Britton, S.C. Bunch, W.L. Dunn, C.M. Henderson, T.J. Sobering, R.D. Taylor, T.C. Unruh, D. S. McGregor, "Preliminary Tests of a High Efficiency 1-D Silicon Pixel Array for Small Angle Neutron Scattering," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

M. F. Ohmes, J. K. Shultis, D. S. McGregor, "3D Real-Time in-Core Neutron Flux Mapping with Micro-Pocket Fission Detectors (MPFD)," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

M.J. Harrison, A. Kargar, D.S. McGregor, "Improved Fabrication of Frisch Collar CdZnTe Gamma Ray Spectrometers," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

S.L. Bellinger, W.J. McNeil, T.C. Unruh, D.S. McGregor, "Angular Response of Perforated Silicon Diode High Efficiency Neutron Detectors," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

D.S. McGregor, S.L. Bellinger, D. Bruno, S. Cowley, W.L. Dunn, M. Elazegui, W.J. McNeil, H. Oyenan, E. Patterson, J.K. Shultis, G. Singh, C.J. Solomon, A. Kargar, T. Unruh, "Wireless Neutron and Gamma Ray Detector Modules for Dosimetry and Remote Monitoring," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

C.J. Solomon, J.K. Shultis, D.S. McGregor, "Angular Efficiency Design Considerations for Perforated Semiconductor Neutron Detectors," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

Y. Cui, A. Bolotnikov, G. Camarda, A. Hossain, R.B. James, G. De Geronimo, J. Fried, P. O'Connor, A. Kargar, M. J. Harrison, D. S. McGregor, "Hand-Held Gamma-Ray Spectrometer Based on High-Efficiency Frisch-Ring CdZnTe Detectors," IEEE Nuclear Science Symposium, Waikiki, Hawaii, Oct. 28-Nov. 3, 2007.

F.P. Doty, D. McGregor, M. Harrison, K. Findley, R. Polichar, "Structure and Properties of Lanthanide Halides," Proc. SPIE, 6707 (2007) pp. 051-0511.

A.M. Hageman, M.J. Harrison, N. Fritz , T.N. Krehbiel, R. White, J. Patenaude, D.S. McGregor, "Purification of Tellurium to 6N Using a Multistage Vacuum Distillation Method," Proc. SPIE, 6707 (2007) pp. 0Z1-0Z7.

A. Kargar, R.B. Lowell, M.J. Harrison and D.S. McGregor, "The Crystal Geometry and the Aspect Ratio Effects on Spectral Performance of CdZnTe Frisch Collar Device," Proc. SPIE, 6706 (2007) pp. 1J1-1J17.

D.S. McGregor, S.L. Bellinger, D. Bruno, W.J. McNeil, E. Patterson, J.K. Shultis, C.J. Solomon, T. Unruh, "Perforated Semiconductor Neutron Detectors for Battery Operated Portable Modules," Proc. SPIE, 6706 (2007) pp. 0N1-0N12.

D.S. McGregor, S.L. Bellinger, D. Bruno, S. Cowley, M. Elazegui, W.J. McNeil, E. Patterson, B.B. Rice, C.J. Solomon, J.K. Shultis, and T. Unruh, "Perforated Semiconductor Neutron Detector Modules for Detection of Spontaneous Fission Neutrons," IEEE Conference on Technologies for Homeland Security, Woburn, MA, May 16-17, 2007.

D.S. McGregor, S. Bellinger, D. Bruno, W.J. McNeil, E. Patterson, B.B. Rice, "Perforated Semiconductor Neutron Detector Modules," Proc. of 32nd Annual GOMACTech Conf., Lake Buena Vista, FL, March 19-22, 2007.

D.S McGregor, A. Kargar, W.J. McNeil, M.F. Ohmes, B. Rice, J.K. Shultis, T. Unruh, "Detector Development in the Kansas State University SMART Laboratory," ANS Topical Meeting, Albuquerque, NM, Nov. 12-16, 2006.

W.J. McNeil, S. Bellinger, T. Unruh, E. Patterson, A. Egley, D. Bruno, M. Elazegui, A. Streit, D.S. McGregor, "Development of Perforated Si Diodes for Neutron Detection," IEEE Nuclear Science Symposium, San Diego, CA, Oct. 29-Nov. 3, 2006.

M. F. Ohmes, A. S. M. S. Ahmed, R. E. Ortiz, J. K. Shultis, D. S. McGregor, "Micro-Pocket Fission Detector (MPFD) Performance Characteristics," IEEE Nuclear Science Symposium, San Diego, CA, Oct. 29 - Nov. 3, 2006.

J.L. Britton, S.C. Bunch, B.J. Blalock, C.L. Britton, D.S. McGregor, L. Crow, "PATARA: Solid-State Neutron Detector Readout Electronics with Current-Mode Pole-Zero and Shaping and Gated Baseline Restorer for the SNS," IEEE Nuclear Science Symposium, San Diego, CA, Oct. 29-Nov. 3, 2006.

D.S. McGregor, et al., "Perforated Semiconductor Diodes for High Efficiency Solid State Neutron Detectors," presentation recorded in the conference record of the Workshop on Use of Monte Carlo Techniques for Design and Analysis of Radiation Detectors, Coimbra, Portugal, September 15-17, 2006.

S. Bunch, J.L. Britton, B. J. Blalock, C. L. Britton, D.S. McGregor, R. Taylor, T. Sobering, D. Huddleston, W. McNeil, T. Unruh, B.B. Rice, S. Bellinger, B. Cooper, L. Crow, 2006. "HENDA and Patara: A solid state neutron detector and a prototype readout chip for the SNS," VIth International Meeting on Front End Electronics for High Energy, Nuclear, Medical and Space Applications, 17-20 May 2006, Perugia, Italy.

W.L. Dunn, Q.M. Jahan, D.S. McGregor, W. McNeil, E.L. Patterson, B. Rice, J.K. Shultis, C.J. Solomon, "Design and Performance of a Portable Neutron Dosimeter," Proc. 2nd Workshop on European Collaboration for Higher Education in Nuclear Engineering and Radiological Protection, 12-15 March, 2006, Valencia, Spain (in press).

J.E. Rauch, M. Gersten-Rauch, A. Burger, D.S. McGregor, A.W. Hunt, R. Spaulding, D. King, D. Beutler, J. Riordan, B. Failor, J. Levine, P. Coleman, R. Sobolewski, A. Verevkin, F. Young, C. Delacruz, and K.Campbell, "GaAs - A Versatile Photoconductive Material for the Measurement of X-Rays in Pulse Power Applications," 15th IEEE International Pulsed Power Conference, Monterey, California, June 13 - 17, 2005.

J.K. Shultis and D.S. McGregor, "Efficiencies of Coated and Perforated Semiconductor Neutron Detectors," IEEE Nuclear Science Symposium, Rome, Italy, Oct. 18-22, 2004.

A.E. Bolotnikov, G.S. Camarda, G.A. Carini, M. Fiederle, D.S. McGregor, W. McNeil, G.W. Wright, and R. B. James, "Performance Characteristics of Frisch-Grid CdZnTe Detectors," IEEE Nuclear Science Symposium, Rome, Italy, Oct. 18-22, 2004.

D. S. McGregor, J. K. Shultis, M. F. Ohmes, A.S.M. Sabbir Ahmed, R. Ortiz , and K. Hoffert, "Micro-Pocket Fission Detectors (MPFD) for Near-Core and In-Core Neutron Flux Monitoring," ANS 4th International Topical Meeting NPIC & HMIT, Columbus, Ohio, September 19-22, 2004.

Raymond T. Klann, Charles L. Fink, Douglas S. McGregor, and Holly K. Gersch, "Development of Coated Gallium-Arsenide for Neutron Detection Applications," Conference Record of the 12th Biennial RPSD Topical Meeting, Sante Fe, New Mexico, April 14-18, 2002.

Douglas S. McGregor and Robert L. Metzger, "A Geometrically Weighted Frisch-Grid Semiconductor Radiation Detector for Gamma Ray Spectroscopy," Conference Record of the 12th Biennial RPSD Topical Meeting, Sante Fe, New Mexico, April 14-18, 2002.

D.S. McGregor, H.K. Gersch, J.D. Sanders, and R.T. Klann, "Designs for Thin-Film-Coated Semiconductor Neutron Detectors," Conference Record of the IEEE Nuclear Science Symposium, San Diego, California, Nov. 4-9, 2001.

D.S. McGregor, R.T. Klann, H.K. Gersch, E. Ariesanti, J.D. Sanders, and B. VanDerElzen, "New Surface Morphology for Low Stress Thin-Film-Coated Thermal Neutron Detectors," Conference Record of the IEEE Nuclear Science Symposium, San Diego, California, Nov. 4-9, 2001.

J.D. Sanders, J.T. Lindsay, and D.S. McGregor, "Development of a GaAs-Based Neutron Tomography System for the Assay of Nuclear Fuel," Conference Record of the IEEE Nuclear Science Symposium, San Diego, California, Nov. 4-9, 2001.

D.S. McGregor, H.K. Gersch, J.D. Sanders, R.T. Klann, and J.T. Lindsay, "Thin-Film-Coated Detectors for Neutron Detection," Conference Record of the First iTRS International Symposium On Radiation Safety and Detection Technology, Seoul, Korea, July 18-19, 2001.

R.T. Klann, C. L. Fink, D. S. McGregor, and H. K. Gersch, "Development of Semi-Conductor Detectors for Fast Neutron Radiography," Conference Record of the 15th Int. Conf. on Applications of Accelerators in Research and Industry, November, 2000.

H.K. Gersch, D.S. McGregor, and P.A. Simpson, "A Study of the Effect of Incremental Gamma-Ray Doses and Incremental Neutron Fluences Upon the Performance of Self-Biased 10B-Coated High-Purity Epitaxial GaAs Thermal Neutron Detectors," Conference Record of the IEEE Nuclear Science Symposium, Lyon, France, Oct. 15-20, 2000.

D.S. McGregor, J.T. Lindsay, Y-H. Yang, and J.C. Lee, "Bulk GaAs-Based Neutron Detectors for Spent Fuel Analysis," Conference Record of ICONE-8, 8th International Conference on Nuclear Engineering, April 2-6, 2000, Baltimore, MD USA.

R.T. Klann and D.S. McGregor, "Development of Coated GaAs Neutron Detectors," Conference Record of ICONE-8, 8th International Conference on Nuclear Engineering, April 2-6, 2000, Baltimore, MD USA.

D.S. McGregor, S.M. Vernon, H.K. Gersch and D.K. Wehe, "Self-Biased Boron-10 Coated High Purity Epitaxial GaAs Thermal Neutron Detectors," Conference Record of IEEE Nuclear Science Symposium, Seattle, Washington, Oct. 25-29, 1999.

D.S. McGregor and R.A. Rojeski, "Performance of Geometrically Weighted Semiconductor Frisch Grid Radiation Spectrometers," Conference Record of the IEEE Nuclear Science Symposium, Toronto, Ontario, Canada, Nov. 8-14, 1998.

D.S McGregor, Z. He, H.A. Seifert, R.A. Rojeski and D.K. Wehe, "CdZnTe Semiconductor Parallel Frisch Grid Radiation Detectors," Conference Record of the IEEE Nuclear Science Symposium, Albuquerque, New Mexico, Nov. 9-15, 1997.