Homepage for S. Cheenu Kappadath

S. Cheenu Kappadath, Ph.D.


Current Position

Postdoctoral Research Scientist
Department of Physics and Astronomy
Louisiana State University
Baton Rouge, LA 70803-4001. USA

phone: 225-388-8691
fax: 225-388-1222
e-mail: cheenu@rouge.phys.lsu.edu


Graduate Student
Physics Department
COMPTEL Collaboration

Space Science Center
Institute for the Study of Earth, Oceans and Space
39 College Road, Morse Hall, Room 340
University of New Hampshire
Durham, New Hampshire 03824. USA


Professional Information

Ph.D. in Physics, 1998, University of New Hampshire
M.S. in Physics, 1994, University of New Hampshire
B.A. in Physics & Math, 1991, Illinois Wesleyan University

Ph.D. Dissertation:
Measurement of the Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV

Dissertation Director: Dr. James M. Ryan

Resume [pdf-file] [postcript]
Complete CV available upon request.


Research Interests

Gamma-Ray Astrophysics, Diffuse Radiation, Gamma-Ray Bursts,
Cosmic-Ray Physics and Instrumentation Development

My research experience is primarily in the field of experimental gamma-ray astronomy with emphasis on gamma-ray background, Monte-Carlo simulation and data analysis. At present I am an active member of the COMPTEL collaboration; the Imaging Compton Telescope (COMPTEL) is one of the instruments onboard NASA's Compton Gamma Ray Observatory (CGRO) satellite. Within the collabaration I am primarily involved in the study of the instrmental background and the Cosmic Diffuse Gamma-Ray Emission (dissertation subject). I am also involved with the COMPTEL Rapid Gamma-Ray Burst Localization project and with the development and maintainance of the COMPTEL data analysis system.


Ph.D. Dissertation

Measurement of the Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV
[abstract] [thesis on-line]

The Cosmic Diffuse Gamma-Ray Spectrum

The COMPTEL CDG flux measurements in the 1 to 10 MeV range are about 5-10 times lower than the pre-COMPTEL estimates. The CDG measurements show no evidence of the MeV bump in the 1 to 10 MeV range. The integrated flux from 0.8 to 9 MeV is (4.7 1.7) x 10^-3 photons/cm^2-s-sr and that from 9 to 30 MeV is (1.5 0.3) x 10^-4 photons/cm^2-s-sr. This represents the first significant detection (statistical significance of 7.2 sigma) of the CDG emission in the 9 to 30 MeV range. The preliminary COMPTEL CDG estimates reported earlier (Kappadath et al. 1995; 1996; 1997) are in good agreement with these results.

The COMPTEL CDG spectrum is fit to power-law function, A x (E/E0)^-a, where A is the flux normalization, E is the photon energy, E0 is taken to be 5 MeV (the logarithmic-midpoint energy between 0.8 and 30 MeV) and a is the spectral index. The resulting differential photon spectrum from 800 keV to 30 MeV is well described by a photon spectral index of -2.4 0.2 and a flux normalization of (1.05 0.2) x 10^-4 photons/cm^2-s-sr-MeV at 5 MeV.


Publications

COMPTEL Measurements of the Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, R. Diehl, W. Hermsen, M. McConnell, V. Schoenfelder, M. Varendorff, G. Weidenspointner and C. Winkler
BAAS 30 (2), p. 926 (1998)
[abstract]

COMPTEL Measurements of the Cosmic Diffuse Gamma-Ray Spectrum
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, W. Hermsen, M. McConnell, V. Schoenfelder, M. Varendorff, G. Weidenspointner and C. Winkler
HEAD Divisional Meeting, Estes Park, Colorado. Poster Presentation. November 4-7, 1997.
[poster-pdf]

The Total Cosmic Diffuse Gamma-Ray Spectrum from 9 to 30 MeV Measured with COMPTEL
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, R. Diehl, W. Hermsen, M. McConnell, V. Schoenfelder, M. Varendorff, G. Weidenspointner and C. Winkler
Proceedings of the Fourth Compton Symposium, ed. C.D. Dermer, M.S. Strickman and J.D. Kurfess, AIP Conf. Proc. 410 Part II, 1218-1222 (1997) (New York: AIP)
[abstract] [paper-postscript]

The Preliminary Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV Measured with COMPTEL
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, D. Forrest, W. Hermsen, R. Kippen, M. McConnell, V. Schoenfelder, R. van Dijk, M. Varendorff, G. Weidenspointner, and C. Winkler
Astronomy and Astrophysics Supp. Series 120, C619-622 (1996)
[abstract] [paper-postscript]

The Preliminary Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV Measured with COMPTEL
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, D. Forrest, W. Hermsen, R. Kippen, M. McConnell, V. Schoenfelder, R. van Dijk, M. Varendorff, G. Weidenspointner, and C. Winkler
Proceedings of the 24th ICRC (Rome), Vol. 2, 230-233 (1995)
[abstract] [paper-postscript]

The Preliminary Cosmic Diffuse Gamma-Ray Spectrum from 800 keV to 30 MeV Measured with COMPTEL
Kappadath, S. C., J. Ryan, K. Bennett, H. Bloemen, D. Forrest, W. Hermsen, R. Kippen, M. McConnell, V. Schoenfelder, R. van Dijk, M. Varendorff, G. Weidenspointner, and C. Winkler
BAAS 27 (4), p. 1368 (1995)
[abstract]


Improving the Analysis of Gamma-Ray Data from CGRO-COMPTEL
McConnell, M., et al., BAAS 30 (2), p. 827 (1998)
[abstract]

MeV Measurements of Gamma-Ray Bursts by CGRO-COMPTEL
Connors, A., et al., BAAS 29 (x), p. xxx (1997)
[abstract]

The Extragalactic Diffuse Gamma-Ray Emission
Sreekumar, P., F. Stecker and S. C. Kappadath
Proceedings of the Fourth Compton Symposium, ed. C.D. Dermer, M.S. Strickman and J.D. Kurfess, AIP Conf. Proc. 410 Part I, 344-358 (1997) (New York: AIP)
[paper-postscript]

The Prompt Cosmic-Ray Induced Background in the Orbiting Compton Telescope COMPTEL
Ryan, J. M., et al., CHERBS Proceedings - in press (1997)
[abstract]

Improved COMPTEL 10-30 MeV Event Selections for Point Sources from Inflight Data
Collmar, W., et al., Proceedings of the Fourth Compton Symposium, ed. C.D. Dermer, M.S. Strickman and J.D. Kurfess, AIP Conf. Proc. 410 Part II, 1587-1591 (1997) (New York: AIP)
[paper-postscript]

MeV Measurements of Gamma-Ray Bursts by CGRO-COMPTEL
Connors, A., et al., Proceedings of the 4th Huntsville Gamma-Ray Burst Symposium, AIP - in press (1997)

The Response of the CGRO COMPTEL Determined from Monte Carlo Simulation Studies
Stacy, J. G., et al., Astronomy and Astrophysics Supp. Series 120, C691-694 (1996)
[abstract]

The Local Neutron flux at Low Earth-Orbiting Altitudes
Weidenspointner, G., et al., Astronomy and Astrophysics Supp. Series 120, C631-634 (1996)
[abstract]

The Local Neutron flux at Low Earth-Orbiting Altitudes
Weidenspointner, G., et al., COSPAR-Birmingham (1996)

Work in Progress


Links

Some interesting URL links to explore...
The COMPTEL Page
The COMPTEL GRB Page
CNN Interactive

Disclaimer
I may eventually get around to making this home page a more useful repository for interesting information related to my research, but for now the best way to get in touch with me is via e-mail or phone.

Thanks for checking in!

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Creation Date: Tue Nov 11, 1997