ILC NewsLine
Algorithms Flow at Detector Simulation Workshop

Full event reconstruction with a particle flow algorithm.

Last month in Boulder, Colorado, about 30 scientists shared ideas and worked together on software problems at the American Linear Collider Physics Group Detector Simulation Workshop.

"This was a software mini-workshop.", said SLAC's Norman Graf who was a member of the workshop's Organizing Committee, together with Uriel Nauenberg and Stephen Wagner of the University of Colorado and Anthony Johnson of SLAC. "The goal is to provide an informal atmosphere for people to get together and exchange ideas. We try to get the experts together with the software users in an informal atmosphere, and ask questions, brainstorm and do some design work. This workshop was particularly nice because we had a large number of graduate and undergraduate students from the University of Colorado attend."

The Detector and Simulation working group within the American Linear Collider Physics Group (ALCPG) is currently developing simulation and event reconstruction software to be used in a generic linear collider detector work environment. "We have been tasked with an extremely ambitious goal to have complete simulation and reconstruction software working ten years before the machine is built.", Graf said. "A lot of experiments don't do that until right before the data arrives. We are trying to design the detector using the results of the simulations. Our motivation is to build the best possible detector. This is a very expensive endeavor, and we want to squeeze the most physics out of it."

Collaborating with a group from SLAC, Steve Magill of Argonne National Laboratory, concentrates on matching hits in the detector with particle showers by using particle flow algorithms. Magill, who attended the workshop, uses these algorithms, along with the simulated data, to optimize the calorimeter detector for the ILC. "Traditional calorimeter designs have not taken advantage of the new opportunities that will be present at the ILC.", Magill said. "Because of the physics at the ILC, calorimeters can be constructed to provide much more precision in particle energy measurements than at existing and previous colliders. Our aim is to significantly improve the calorimeter performance to take advantage of the ILC e+e- collider environment, thus making much more precise measurements of jets using the combined calorimeter and tracking detectors in a particle flow algorithm."

These particle flow algorithms are meant to link the hits in the calorimeter to both charged and neutral particles. Magill compares it to putting a very complicated puzzle together. "We have to rely on simulations to show that the algorithm works.", he said. "We are excited about the possibilities of calorimeter optimization at the ILC, and we are developing and using particle flow algorithms to achieve this."

The next software mini-workshop will be on 4-6 April 2006 in Cambridge, England. Argonne is also hosting CALOR2006, the 12 th International Conference on Calorimetry in High Energy Physics, on 5-9 June 2006 in Chicago, USA.

-- Elizabeth Clements
Rather than planning a lot of talks, the organizers designed the detector simulation workshop so that the attendees had a lot of time to work on problems together. A real blackboard even got used during the workshop.