BRIAN R. DENNIS

POSITION

Astrophysicist, Solar Physics Branch, Code 682

 

Laboratory for Astronomy and Solar Physics (LASP)

 

NASA Goddard Space Flight Center

Greenbelt, MD 20771

EDUCATION

B. Sc. (Physics), University of Leeds, England, 1961

 

Ph. D. (Cosmic Ray Physics), University of Leeds, England, 1964

PROFESSIONAL SPECIALTY

X-Ray and Gamma-Ray Astronomy and Solar Physics

PREVIOUS POSITIONS

1964 - 1967

Research Associate, University of Rochester

 

1967 - 1969

NRC Research Fellow, GSFC

MAJOR RESPONSIBILITIES

1997 - present

Mission Scientist and Co-I on the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

2000 - present

COTR of SBIR contracts with Mikro Systems, Inc. to make multi-grid arrays for X-ray imaging

2001 - present

ATR on SSAI contract for Solar Flare X-ray Data Support

1998 - 2001

ATR on Raytheon contract for Solar Flare X-ray Data Support

2001

Co-I on MIDEX proposal for the Heliospheric Explorer (HELIX)

2000

Co-I on SMEX proposal for the Cyclotron/Nuclear Explorer (Cyclone)

1996

Co-I on MIDEX Proposal for the High Energy Solar Spectroscopic Imager (HESSI)

1994 - 1999

Co-I for the X-Ray Spectrometer (XRS) on the Small Spacecraft Technology Initiative (SSTI) Clark mission

1991 - 1999

PI of a Compton Gamma Ray Observatory (CGRO) Guest Investigator Program

1991 - 1996

PI for the X‑Ray Spectrometers on the Argentinean Satelite de Aplicaciones Cientificas-B (SAC‑B)

1991 - 1995

Study Scientist for the High Energy Solar Imager (HESI - formerly HESP)

1989 - 1995

Co-chair with Richard Canfield of the Max ’91 Program

1982 - 1990

PI of the Hard X-Ray Burst Spectrometer (HXRBS) on the Solar Maximum Mission

1972 1978

CoI on the High Energy Celestial X-ray Detector on the 8th Orbiting Solar Observatory (OSO-8)

 

 

 

 

AWARDS

2004 NASA Outstanding Leadership Medal

2004 Goddard Lindsay Award

2004 Group Achievement Award - RHESSI Data Analysis Team

2004 NASA Thirty-five Year Service Award

2003 NASA Group Achievement Award RHESSI Principal Investigator Team

2000 NASA Group Achievement Award HESSI Imaging Hardware Team

AFFILIATIONS

Fellow of the American Physical Society, member of the High Energy Astrophysics Division

Member of the American Astronomical Society and its Solar Physics Division

Member of the American Geophysical Union

Member of the International Astronomical Union

PUBLICATIONS

Over 100 first-authored and co-authored papers in refereed scientific publications including the following:

Emslie, A. G., Dennis, B. R., Holman, G. D., and Hudson, H. S., ‘Refinements to flare energy estimates a follow-up to “Energy Partition in Two Solar Flare/CME Events,”’ J. Geophys. Res., submitted, 2005.

Dennis, B. R., Hudson, H. S., and Krucker, S., “Review of RHESSI Solar Results”, proc. CESRA meeting, Scotland, 2004, submitted.

Dennis, B. R., Phillips, K.J.H., Sylwester, J., Sylwester, B., Schwartz, R.A., and Tolbert, A.K., “Thermal_and_Nonthermal_Contributions_to_the_Solar_Flare_X-ray_Flux,” COSPAR presentation, Advances in Space Research, 2005, in press.

Emslie, A. G., Kucharek, H., Dennis, B. R., Gopalswamy, N., Holman, G. D., Share, G. H., Voulidas, A., Forbes, T. G., Gallagher, P. T., Mason, G. M., Metcalf, T. R., Mewaldt, R. A., Murphy, R. J., Schwartz, R. A., and Zurbuchen, T. H., “Energy partition in two solar flare/CME events” J. Geophys. Res., 109, A10104, 2004.

Sui, L., Holman, G. D., and Dennis, B. R “Evidence for Magnetic Reconnection in Three Homologous Solar Flares Observed by RHESSI,” ApJ, 612, 546 556, 2004.

Gallagher, P. T., Lawrence, G. R., and Dennis, B. R., “Rapid Acceleration of a Coronal Mass Ejection in the Low Corona and Implications for Propagation” ApJ Letters, 588, L53, 2003.

Lin, R. P.; Krucker, S.; Hurford, G. J.; Smith, D. M.; Hudson, H. S.; Holman, G. D.; Schwartz, R. A.; Dennis, B. R.; Share, G. H.; Murphy, R. J.; Emslie, A. G.; Johns-Krull, C.; Vilmer, N., “RHESSI Observations of Particle Acceleration and Energy Release in an Intense Solar Gamma-Ray Line Flare,” ApJ., 595, L69-L76, 2003.

Hurford,G.J., Schmahl,E.J., Schwartz,R.A., Conway,A.J., Aschwanden,M.J., Csillaghy,A., Dennis,B.R., Johns-Krull,C., Krucker,S., Lin,R.P., McTiernan,J., Metcalf,T.R., Sato,J., and Smith,D.M., “The RHESSI Imaging Concept” Solar Physics 210, 61-86, 2002.

Gallagher, P. T., Dennis, B. R., Krucker, S., Schwartz, R. A., and Tolbert, K., “Observations of the 21 April 2002X1.5 Flare,” Solar Physics, 210, 341 - 356, 2002.

Sui, L., Holman, G. D., Dennis, B. R., Krucker, S., Schwartz, R. A., and Tolbert, K., “Modeling Images and Spectra of a Solar Flare Observed by RHESSI on 20 February 2002” Solar Physics, 210, 245 259, 2002.

Dennis,B.R., Veronig,A., Schwartz,R.A., Sui,L., Tolbert,A.K., Zarro,D.M. and the RHESSI Team, “The Neupert Effect and new RHESSI measures of the total energy in electrons accelerated in solar flares” COSPAR Colloquia Series, "Energy Release and Particle Acceleration in the Solar Atmosphere - Flares and Related Phenomena", (eds. B.Dennis, R.Lin, and T.Kosugi), Elsevier, , Advances in Space Research, Volume 32, Issue 12, p. 2459-2464. 2003

Lin,R.P., Dennis,B.R., and Benz,A.O. (eds.) “The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) - Mission Description and Early Results” Kluwer Academic Publishers, (ISBN: 1-4020-1107-5) 464 pp., March 2003, reprinted from Solar Physics, Vol. 210, Nos. 1-2, 2002.

Lin,R.P., Dennis,B.R., and 64 co-authors, “The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)” Solar Physics 210, 3-32, 2002.

Zehnder, A.; Bialkowski, J.; Burri, F.; Fivian, M.; Henneck, R.; Mchedlishvili, A.; Ming, P.; Welte, J.; Thomsen, K.; Clark, D.; Dennis, B. R.; Hurford, G. J.; Curtis, D. W. ; Harvey, P. R.; Pankow, D. H., “RHESSI Imager and Aspect Systems,” in Innovative Telescopes and Instrumentation for Solar Astrophysics, S. L. Keil and S. V. Avakyan (eds). Proc. SPIE, 4853, 41-59, 2003.

Sui,L., Holman,G.D., Dennis,B.R., Krucker,S., Schwartz,R.A., and Tolbert,K., “Modeling images and spectra of a solar flare observed by RHESSI on 20 February 2002” Solar Physics 210, 245-259, 2002.

Gallagher,P.T., Dennis,B.R., Krucker,S., Schwartz,R.A., and Tolbert,K., “RHESSI and TRACE observations of the 21 April 2002 X1.5 flare” Solar Physics 210, 341-356, 2002.

Share,G.H., Murphy,R.J., Dennis,B.R., Schwartz,R.A., Tolbert,A.K., Lin,R.P., and Smith,D.M., “RHESSI observations of atmospheric gamma rays from impact of solar energetic particles on 21 April 2002” Solar Physics 210, 357-372, 2002.

R. P. Lin and B. R. Dennis, “The High Energy Solar Spectroscopic Imager (HESSI) Mission” in American Geophysical Union, Spring Meeting, abstract #SP42A-01, 2001

S. E. Boggs, R. P. Lin, B. R. Dennis, P. Von Ballmoos, K. Thomsen, G. Hurford, K. C. Hurley, N. W. Madden, D. M. Smith, P. Jean, and J. Knoedelseder, "Cyclone, The Cyclotron/Nuclear Explorer" AAS/High Energy Astrophysics Division, 32, 2000.

R. Henneck, J. Bialkowski, F. Burri, M. Fivian, W. Hajdas, A. Mchedlishvili, P. Ming, K. Thomsen, J. Welte, A. Zehnder, B. R. Dennis, G. J. Hurford, D. W. Curtis, and D. Pankow, "Solar Aspect System (SAS) for the High-Energy Solar Spectroscopic Imager (HESSI)" in Proc. SPIE Vol. 3765, p. 771-776, EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy X, Oswald H. Siegmund; Kathryn A. Flanagan; Eds., 771, 1999.

Lin, R. P., Hurford, G. J., Madden, N. W., Dennis, B. R., et al. “High-Energy Solar Spectroscopic Imager (HESSI) Small Explorer mission for the next (2000) solar maximu” in Proc. SPIE Vol. 3442, p. 2-12, Missions to the Sun II, Clarence M. Korendyke; Ed., 2, 1998.

M. J. Aschwanden, B. R. Dennis, and A. O. Benz, 1998, “Logistic Avalanche Processes, Elementary Time Structures, and Frequency Distributions in Solar Flares” Astrophysical Journal, 497, 972, 1998.

J. A. Miller, P. J. Cargill, A. G. Emslie, G. D. Holman, B. R. Dennis, T. N. LaRosa, R. M. Winglee, S. G. Benka, and S. Tsuneta, “Critical Issues for Understanding Particle Acceleration in Impulsive Solar Flares” JGR, 102, pp 14,631-14,659, 1997.

B. R. Dennis, R. P. Lin, R. C. Canfield, C. J. Crannell, A. G. Emslie, G. D. Holman, H. S. Hudson, G. J. Hurford, J. C. Ling, N. W. Madden, and R. Ramaty, “The High Energy Solar Spectroscopic Imager HESSI” Proc. SPIE Technical Conference Missions to the Sun, Denver, Colorado. 2804, pp 228-240, 1996.

B. R. Dennis, “X-Ray Aspects of the High Energy Solar Physics Workshop: Rapporteur Paper I” High Energy Solar Physic, (R. Ramaty, N. Mandzhavidze, and X.-M. Hua, eds.), AIP Press, Conf. Proc. 374, pp 519-532, 1996.

T. A. Kucera, B. R. Dennis, R. A. Schwartz, and D. Shaw, “Evidence for a Cutoff in the Frequency Distribution of Solar Flares from Small Active Regions” Ap. J., 475, pp 338-347, 1996.

T. A. Kucera, P. J. Love, B. R. Dennis, G. D. Holman, R. A. Schwartz, and D. M. Zarro, “A Study of the Thermal/Nonthermal Electric Field Model Using Spectral and Spatial X-Ray Data from the Compton Gamma Ray Observatory and Yohkoh” Ap. J., 466, pp 1067-1077, 1996.

H. S. Hudson, K. T. Strong, B. R. Dennis, D. M. Zarro, M. Inda, T. Kosugi, and T. Sakao, “Impulsive Behavior in Solar Soft X-Radiation” Ap. J. Letters, 422, pp. L25‑L27, 1994.

N. B. Crosby, M. J. Aschwanden, and B. R. Dennis, “Frequency Distributions and Correlations of Solar X-Ray Flare Parameters” Solar Physics, 143, 275-299, 1993.

B. R. Dennis and D. M. Zarro, “The Neupert Effect: What Can It Tell Us about the Impulsive and Gradual Phases of Solar Flares?” Solar Physics, 146, pp. 177-190, 1993.

BRIAN R. DENNIS

Brief Biography:

Dr. Brian R. Dennis was educated in England at Queen Elizabeth's Grammar School, Horncastle, Lincolnshire, and at the University of Leeds, Yorkshire. He received his Ph.D. at Leeds in 1964 and immediately moved to the United States to become a research associate at the University of Rochester, New York. He became a National Research Council Resident Research Associate at Goddard Space Flight Center in 1967, a government employee at GSFC as an astrophysicist in 1969, and a U.S. citizen in 1975. Working in the Solar Physics Branch at Goddard, Dr. Dennis has been involved in designing, building, operating, and analyzing data from several X-ray and gamma-ray instruments for observations of solar flares and cosmic X-ray sources. He was a Co-investigator of the Celestial X-Ray Spectrometer on the 8th Orbiting Solar Observatory and Principal Investigator (PI) of the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission (SMM). He co-chaired the Max ’91 program to coordinate observations of solar activity during the solar maximum centered around 1991. He is the Mission Scientist and lead Co-I of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), a NASA Small Explorer (SMEX) mission launched on 5 February 2002. In 2004, Dr. Dennis received the Goddard Lindsay Award and a NASA Outstanding Leadership Medal for over two decades of work in high energy solar physics that has culminated with the ongoing success of RHESSI.

Research Interests

Dr. Dennis has been interested in high-energy phenomena in the universe, starting with cosmic ray observations, then X-ray observations, and since 1980, with X-ray observations of solar flares. He is particularly interested in the development of advanced instrumentation for X-ray imaging spectroscopy of solar flares with both high energy resolution and high angular resolution.