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Decay Muons

Events generated with the LUND Monte Carlo for trigger studies are used in this analysis. Kinematic information of all particles reaching the CTB is recorded for each event. A total of 800 central AuAu events are used to obtain the results presented in this report. A central event is defined as an collision where the impact parameter between the two nuclei is smaller than 3 fermi. This corresponds approximately to 10%of the total inelastic cross section. The results are not expected to change in a significant way if a more stringent centrality criteria was to be used.

In addition to the particles decaying into muons before reaching the CTB, there are some decaying behind it. However due to the short distance between the CTB and the EMC -where the dense material starts- muons produced in that way, should be of the order of a few percent of the total number. Therefore in this study only muons produced before the CTB are considered.

The material between the interaction point and the proposed muon chambers corresponds to about 5 interaction lengths (). Taking this into account, the minimum momentun a muon perpendicular to the beam needs to cross before reaching the muon chambers is 1.14 GeV [1]. The absorber is aproximately a cylindrical annulus of iron, so the thickness particles cross depends on the polar angle. The minimum momentum for a given particle can be expressed by: [1] This implies that particles with a transverse momentum, pt, larger than will reach the chambers.

Figure 1 shows the pt distribution of all muons reaching the CTB in linear and log scales. Also the minimum transverse momentum a muon needs to go through the absorber is indicated. As can be observed most of the muons are below .

Figure 2 shows the percentage of muons passing the absorber, GeV, per event. As can be observed around 25%(8%) of the events have one (two or more) muon(s).

Next: Up: No Title Previous: Introduction
Fri Apr 15 17:13:51 EDT 1994