COLLOSAL Measure air shower rates among multiple schools

1. COLLOSALMeasure air shower rates among multiple schools Goal is to prove that QuarkNet Large Array operation has intellectual merit - can detect correlated showers; do real physics If there are no correlated events in existing data, set up multiple sites close enough to each other to guarantee success!

2. What do we know? • Scaling results of rates versus detector size • UIC Workshop measurements give rates vs size • Multiple array rates versus array separation • UIC 2005 measurement from several meters to 150m array separation • Searches for correlated events in QuarkNet multi-school data • CLASA Spring 2009 • WH15W-Lab6-Geneva

3. GBS Scaling Results 2008 GBS Workshop2007 High statistic follow-up Rate per minute Rate drops factor 10 as array size changes from 1m to 5m counter separation (m)

4. Two-Array Rate versus Separation Rate between schools ~1/month Need patience, live time and many pairs of schools (2005)

5. Searches for multi-school events • UIC C-J arrays 2006-2007 150m apart • 1 event/day (array sizes 8m, 15m) • UIC-Hubbard (2005); WH15W-Geneva 2006 10km apart • Both: few events in 2 weeks (but did not understand out of time) • CLASA Spring 2009 UIC-WPCP 4 km apart • No events in 2 weeks • Lab6-WH15W 4 km apart • No correlations found in 20 days using 10 microsecond window. Estimated randoms at 10E-3/day. Increased window to 10ms and found 24 events in 20 days as expected

6. denotes CLASA Spring 2010 sites Search in pairs of nearest sites: UIC-WPCP WH-Lab6-Geneva Was GBN online?

7. How to assure success before a future massive effort at Fermi • Analyze existing CLASA data • Need more data and closer sites • Need to maximize rates by shrinking size of each array Suggested Hardware Program • GBS1-GBS2 50-200 m apart • Optimize array size to maximize correlation and apply to future multi-school attempts • GBS-GBN 3 km apart • PW-PMSA 5.5 km apart; WH-Lab6 4 km

8. How do we optimize arrays for multi-site correlation measurement? • Highest single muon rates occur with stacked arrays (5Hz) • Problem is that randoms dominate even if only one array is stacked • RR = (5Hz)(0.1Hz)(10ms window) = 5E-6 Hz or 0.4 randoms/day • Lower array rate or add pointing info • Use horizontal geometry • Requires 2 muons, but we are looking for huge events with thousands of muons; need to keep acceptance high for those very energetic showers • Larger arrays can be used to point to cut down on randoms, BUT are randoms a problem once horizontal arrays are used? • RR = (0.1Hz)(0.1Hz)(10ms window) = 1E-7 Hz or 0.2 random/month • Study correlation rate (at GBS?) versus array size • Rate increases with smaller array but that may not increase correlation rate at 100m or 10km. Measure at 100m first. • Showers were search have thousands of muons, but are they clustered?

9. Four Proposals • Search in existing HS-HS data for correlations to produce upper limits • Measure correlation rate at 50-100m as a function of array size (anywhere with two arrays) • Build a 1km separation test • At large separations 5-10km, obtain more data using the optimum array size from above and search again