The JEM-EUSO research group in The Leonard E Parker Center for Gravitation, Cosmology and Astrophysics is supported by the NASA (11-APRA11-0058), UW-Milwaukee College of Letters and Science, and UW-Milwaukee Graduate School. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of these organizations.
The Extreme Universe Space Observatory (EUSO) attached to the Japanese Experiment Module (JEM) on board the International Space Station (ISS) is the first space mission concept devoted to the investigation of cosmic rays and neutrinos of exteme energy, E > 50 EeV. The extreme energy cosmic ray flux is exceptionally low, of the order of 1 particle/km2/sr/century. At the high end of the spectrum, E > 100 EeV, it reduces to about 1 particle/km2/sr/millennium! This challenging extreme energy region is the scope of JEM-EUSO.
When one of these particles reaches Earth, it collides with an air nucleus high in the atmosphere, producing many secondary particles, which share the original primary particle's energy. The secondary particles subsequently collide with other nuclei in the atmosphere, creating a new generation of energetic particles that continue the process, multiplying the total number of particles. The resulting particle cascade, called "an extensive air shower," arrives at ground level with billions of energetic particles extending over an area as large as 10 square miles.
JEM-EUSO will exploit the Earth’s atmosphere as a detector of extensive air showers. The remote-sensing space instrument would orbit the Earth every 90 minutes on the ISS at an altitude of 350 − 40 0km. The EUSO instrument is a 2.5 meter telescope with a high-speed ultraviolet (UV) camera that will observe the nighttime atmosphere below the ISS with a 60 degree field of view. It will monitor an area larger than one hundred thousand square kilometers, recording video clips of fast UV flashes by sensing the fluorescence light produced through charged particle interactions. This fluorescence is detectable in the 300 − 400nm range.
The UWM Scientists will coordinate development of the groundbased computer software used to analyze data recorded by JEM-EUSO. The development of analysis techniques will be a collaborative effort, involving some 300 collaborators from 13 countries. JEM-EUSO collaborators will share a common software framework, hosted at UWM, in which individual teams can "plug in" their techniques to reduce the data recorded by various JEM-EUSO instruments into science results. This approach will foster friendly competition among analysis groups and reduces unnecessary duplication of software.
NASA support will allow us to augment the LIGO computing facilities hosted by the CGCA with additional modest resources required to host the common JEM-EUSO analysis software repository, to organize and track the development of the software project, and to continuously run an extensive battery of tests to ensure the software base remains robust, reliable and as bug-free as possible during periods of vigorous development.
In the near future, the UWM Scientists will use the analysis framework to evaluate data from JEM-EUSO prototype instruments, one ofwhich will be colocated with an established terrestrial cosmic ray detector, called the Telescope Array, and another of which will be flown aboard a high altitude balloon. Once JEM-EUSO is on orbit, our team plans to specialize in hunting for hints of exotic physics in extremely high energy events, including possible signatures of supersymmetry and string theory.
The UWM team has a long history of studying cosmic ray phenomenology, which involves synthesizing new ways to interpret data in light of the latest theoretical ideas. JEM-EUSO will produce data at the highest energies ever observed, providing us with a new realm for phenomenological exploration.
The JEM-EUSO Collaboration at UWM is currently supported by the NASA 11-APRA11-0058 Award.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of NASA.