Z PRIME (MASS 371 GEV) CANDIDATE DECAYING INTO ELECTRON PAIR

version 0.90, John Yoh, 1/7/05

Here, we have the event displays of an event which is a candidate of a Excited Z, with mass (371 GeV) roughly 4 time heavier than the Z boson, which subsequently decays into an electron pair (note : we use the "electron" as a generic designation for both electron and the positron, its antiparticle)--although it is most likely just a part of the cotinuum distribution of di-electrons from 'old physics'.

Figure to the right shows the end-view of the tracking system along with the calorimetry, indicating 2 stiff tracks (those that shows almost no bending, and thus is measured to have a very high Momentum). Both tracks, which does not have other high energy tracks nearby (we call these "isolated" tracks) also point directly to energy deposits in the front EM ealorimetry (shown here in purple--with the length of the column proportional to the energy), with Energy consistant with the track momentum !! thus confirming that this is an electron candidate (only electrons and photons deposit almost all their energies in the front EM calorimeter--most other particles such as pions, kaons, and protons would penetrate deeper and deposit much of their energies in the second calorimetry layer--the HAD (Hadron) calorimetry--shown in Blue--the small amount of blue compare to the purple indicate electron or photon-like characteristics).

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The next figure shows a "Lego" plot of the energy deposited-- where we see practically that the only significant energy deposited are those from the 2 electrons.