Nishu Karna Mentor:Dr. William Dean Pesnell Code: 671 SESI Program-2009 Goddard Space Flight Center St. Cloud State University Date: August 5, 2009 RELATIVISTIC ELECTRONS

Definition: Electrons carrying the energies over 500 keV and moving near the speed of light is called Relativistic electrons. Relativistic electrons are accelerated by the result of high-speed solar wind streams interacting with the magnetosphere. Magnetospheric electric and magnetic field fluctuation produces radial diffusion that transport electrons from the plasma sheet towards the Earth. “Children moving around adult”

Upper Atmosphere Research Satellite (UARS): It was launched in September 15,1991 by Space Shuttle Discovery at an altitude of 375 miles with an orbital inclination of 57°. Instrument was set up with four solid-state detector telescope at an angle of -15°, +15°,+45° and +90°. It carried out ten instruments in which we read data from Particle Environment Monitor (PEM). PEM measured the type, amount, energy and distribution of particles (electron, protons and X-rays) injected into the Earth’s thermosphere, mesosphere and stratosphere.

PEM consists of four instruments:- High-energy Particle Spectrometer (HEPS) Atmospheric X-ray imaging Spectrometer (AXIS) Medium-energy Particle Spectrometer (MEPS) Vector Magnetometer (VMAG) The HEPS instrument consists of six silicon detector telescopes and two surface barrier detectors. These detectors measure protons in the energy range from 0.1 to 150 MeV and electrons from 0.03 to 5 MeV.

The objective of the PEM investigation was to determine the global input of charged particle energy into the Earth's stratosphere, mesosphere, and thermosphere, and to understand the atmospheric processes involved. Our objective was to use the HEPS data(from 20 UARS day to 5095 UARS day) from Goddard Earth Science Distributed Active Archive Center (GES-DAAC) to see electrons for the whole solar cycle and find the changes in the number of relativistic electron between the two solar minima. Objectives:

Procedure: HEPS was used to develop a database of the pitch-angle and energy resolved electron fluxes with energies between 30 keV to 5 MeV. We used the data from DAAC and read it into the IDL program. We can easily read the data and create the contour plot showing where the flux measurements was made. We then tried to find the relation between the relativistic flux and solar phenomena by plotting flux versus L Shell at different times.

Above is the data from one day with high solar activity and another with lower. It can be seen that during the sun active period the peak of relativistic electron flux shows up between the 3-4 L- shell whereas during quiet period the relativistic electron flux peak is shown beyond 4 L-shell. Plots: May 12, 1992 Sep 23,1994 UARS Day=244 UARS Day=1108

Drawback:- HEPS can read only data between +65º to -65º latitude. So, relativistic electrons at higher latitude can’t be measured. Most of the HEPS data were missing so I could not get the plot on the everyday basis.

Conclusion: We obtained the contour plot from the HEPS data that clearly showed when the data existed. But while plotting data through the Flux verses L-Shell we found that the lots of data were missing for many days so, we cannot calculate change in number of relativistic electrons between two solar minima. But from few good plots we can find the position of relativistic electrons in the L-Shell.

Besides Relativistic Electron:- Learned to use IDL Learned about Sun (sunspot, coronal loop). Learned how to referee a paper. Opportunity to meet with Astronauts. Opportunity to meet many Scientists. Finally, improved English to some extent.

THANK YOU!

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