Endcap etas

Endcap etas

This analysis to look for etas at higher energy is in part motivated by this study. The interest in etas, of course, is that their decay photons are well separated at moderate energies (certainly more separated than the photons from pi0 decay). I ran Weihong's pi0 finder with tower seed threshold of 0.8 GeV and SMD seed threshold of 5 MeV (I believe his default SMD seed setting is 2 MeV). I then look in the 2-photon invariant mass region between 0.45 and 0.65 GeV (the PDG nominal mass for the eta is 0.54745 +/- 0.00019 GeV). I observe what looks like a faint eta peak. The dataset processed is the longitudinal 2 run of 2006 from the 20 runs sitting on the IUCF disk in Weihong's directory (/star/institutions/iucf/hew/2006ppLongRuns/).

Within the reconstructed mass window 0.45 to 0.65 GeV, I take a look at the decay photon shower profiles in the SMD. The samples are saved in the file etas.pdf. For the most part, these shower shapes are cleaner than the original sample. Although the statistics are not great.

Additional Material

• List of etas from Weihong (text file)
• List of etas from Weihong (pdf file)
• List of etas from Weihong using gammma maker
• List of etas from Weihong (all 12 sectors)
• Hal's eta spreadsheet
• Hal's revised eta spreadsheet

Documents

• Direct photon center-of-mass angular distributions in proton-antiproton collisions at sqrt(s)=1.8 TeV (Leslie Nakae Thesis)
• Measurement of the cross section for production of two isolated prompt photons in 1.8-TeV proton-antiproton collisions (Mikio Takano Thesis)
• Measurement of sqrt(s) dependence of isolated direct photon production in proton-antiproton collisions (Dana Partos)
• Prompt photon cross section measurement in pbar-p collisions at sqrt(s)=1.8 TeV (PRD 48 2998, 1993)
• A prompt photon cross section measurement in pbar-p collisions at sqrt(s)=1.8 TeV (FERMILAB-Pub-92/001-E)