Over the last three years I have concentrated on the GLAST reconstruction and analysis. GLAST is a gamma ray satellite mission that will expand on the success of the previous mission, EGRET, by nearly a factor of 100. It will change high-energy astrophysics from a science of exotic examples to one of statistical analysis by providing hundreds to thousands of like objects to study.
My first two years were dominated by writing and creating the track finding and track fitting algorithms presently used in the analysis. A little over year ago my attention turned to calorimetry and overall energy determinations. Finally, with a complete reconstruction in handed, this last year has been focused on the instrument’s performance: image resolution, background separation, trigger studies and the like. For example, the GLAST science requirement document requires the difficult task of increasing a separation of signal from background noise to the range of 106 to 1 with a loss in signal of less than 20%. This task has fallen to me.
There was an issue of whether or not a feature in the tracker hardware didn’t work because of an error in the circuit design. I used simulations to show what the resulting effect would be on the resulting science if we gave up that feature. As a result the decision was made that the circuit should be fixed at the cost of well over $100K.
Furthermore, from the simulations and their subsequent analysis one frequently discovers subtle problems in the design. Another example was an error in the simulation: the geometry was wrong which had the effect of not allowing us to get to our science requirement of 100,000 to 1 background rejection. A third example was discovery of an error in the multiple scattering routines of the world standard Monte Carlo package used to model the physics in the simulations resulting in making overly optimistic estimates of performance parameters. The core of what I’ve done is contain in the talks given at the three big internal GLAST collaboration meetings since I returned.
The details are contained in the four talks to the Internal GLAST Analysis Group. The next two are talks given to the NASA committee charged with approval of commencing with the construction of the flight instrument. The last two are talks given as part of the SCIPP presentation to its funding agency, DOE, in justification of its inclusion of GLAST among its tasks.
In addition to that, I was elected to the Senior Science Advisory Group. I have served on: the end-to-end testing committee and the calibration review committee.