WALTA school-network cosmic ray detectors

The Washington area large-scale time coincidence array (WALTA) is placing particle detector arrays in secondary schools in the Seattle area to build up a large-scale ultrahigh-energy cosmic ray detector network, one of several such projects around the world. Scintillation counters salvaged from the CASA experiment in cooperation with the CROP group at the University of Nebraska at Lincoln are refurbished by teachers and students, tested, calibrated, and installed in fourfold arrays at high school sites. To identify time coincidences, a GPS time synchronization system is employed. Data are acquired using a custom low-cost data acquisition card. Here we will describe the logistics of WALTA and show samples of data taken with a prototype array at the University of Washington.