Cal Cluster ID (a.k.a. Eflow) Gary R. Bower, SLAC Santa Cruz LCD Workshop June 28, 2002

G.R.Bower - Santa Cruz LCD Workshop 2 Acknowledgement Ron Cassell has made many essential contributions to this project.

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 3 Outline This is a work in progress. (Very preliminary) results first! –Describe test data sets and testing methods. –Efficiencies and fake rates. Details (as time permits) –Approach to problem –Discriminator tools –Discriminator capabilities Summary Next Steps

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 4 Test procedure Three datasets of 1000 single particle events. –piminus, gamma, and K0L –1-50 Gev momentum –In barrel, within 45 o of perpendicular to beam Make contiguous hit clusters –Ignore clusters with energy < 0.5 GeV –Treat most energetic cluster as primary deposition –Treat second most energetic cluster as fragment. Test both primary and secondary cluster –Is it a gamma, piminus, K0L, and/or fragment?

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 5 ID result: gamma piminus K0L fragment Input: gamma piminus KOL fragment

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 6 Multiple ID rates

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 7 Philosophy of Technique The Eflow problem: a common approach: – solve it with a clever cluster builder but still need to identify shower origin. –Assumes showers fragment badly. –Assumes showers overlap each other. We take a different approach: –work with (simple) clusters of contiguous hits. –distinguish origins based on cluster properties

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 8 Fragmentation problem? input piminus

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 9 “Secret” to solving fragmentation problem Combine EM and Had clusters using contiguous hits cluster builder by Ron Cassell. Caveat: For the occasional neutral hadron there will be significant fragments but we have a promising technique to find and associate them.

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 10 Isolation of gammas

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 11 Gamma shower characteristics Compact Standard cigar shape Shower initiates in first few EM layers Shower contained in EM (if deep enough) Many hits/much energy in first few layers Accurately point back to IP

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 12 Piminus shower characteristics Diffuse in shape and energy spread. Some fragmentation. Min-I track begins in first layer. Few hits/little energy until first interaction.

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 13 KOL shower characteristics Diffuse in shape and energy Some fragmentation First hit layer may be very deep Generally points back at IP

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 14 Fragment shower characteristics Diffuse in shape and energy First hit layer may be very deep Generally do not point back at IP

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 15 Measure cluster properties Form energy tensor –Energy (shape) eigenvalues –Energy axes –Center of Energy First and last layers with hits Energy/# of hits in first N layers

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 16 Superb gamma location resolution Resolve gamma direction to ~1/6 cell size using center of energy of hits

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 17 Separating gammas

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 18 Separating piminuses

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 19 Separating K0Ls

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 20 Summary Can find gammas with ~100% efficiency and ~few percent fakes. Can identify most pions without tracking Can identify majority of K0Ls. Have only sketched the power of the method.

June 28, 2002G.R.Bower - Santa Cruz LCD Workshop 21 Next steps (arbitrary order) Many details to cross-check. Reconstruct π 0 s (dE/E~5%, loc res ~same as π ±.) Associate neutral hadron fragments (improve dE/E). Work out special cases, eg, charge exchange. Combine clusters between barrel and endcap. Use neural net to improve results. Test on signal events. Test on physics measurement. Release tools.