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!

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

GBS Scaling ResultsGBS Workshop 2007

High statistic follow-up

2008

Rate vs Distance

0

50

100

150

200

250

300

350

0 1 2 3 4 5

Distance (meters)

Co

un

ts

2-fold

3-fold

4fold

Expon. (2-fold)

Rate drops factor 10 as array size changes from 1m to 5mR

ate

per

min

ute

counter separation (m)

Two-Array Rate versus Separation

Rate between schools

~1/month

Need patience, live time and many pairs of schools

(2005)

Searches for multi-school events

denotes CLASA Spring 2010 sites

Search in pairs of nearest sites:UIC-WPCPWH-Lab6-Geneva

Was GBN online?

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 arraySuggested 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

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)(10s 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)(10s 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?

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