| Invariant mass versus target |
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Here is the CAA document:
This page is set up for a CLAS Approved Analysis to determine the absorption cross sections for omega and phi mesons. The data set to be analyzed is from the g7a experiment which has the ideal design. The target is contains deuterium, C12, Ti48, Fe56, and Pb208 simultaneously in the beam. Each target material is 1 g/cm^2. Furthermore, the CLAS detector is optimized for electron/positron identification with a factor of 10^-5 in electron/pion misidentification.
These plots show the e+e- invariant mass seperated by target. The decrease in omega- and phi-meson peaks with target density is what prompted this analysis.
| Invariant mass versus target |
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Below are the preliminary results of the omega- and phi-meson yields versus the target A. Errors are purely statistical. Systematic errors are under investigation. Furthermore, no normalization has been applied.
| Yields of omega-meson production | Yields of phi-meson production |
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Here I am showing some momentum ditributions for the e+e- pairs. A cut was made on the invariant mass to select the omega- and phi-mesons. In each set of histograms, there are plots of the transverse momentum, longitudinal momentum, and longitudinal mometum for events with a correctly tagged photon.
Here are the distributions for the omega mesons.
| Transverse Momenta for omega mesons | Longitudinal Momenta for omega mesons | Longitudinal Momenta for omega mesons with photon timing |
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Here are the distributions for the phi mesons.
| Transverse Momenta for phi mesons | Longitudinal Momenta for phi mesons | Longitudinal Momenta for phi mesons with photon timing |
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Below are plots of the laboratory polar angle theta of the e+e- pair. The theta acceptance for an individual lepton is defined by the EC and CC which is about 10o to 50o.
| Lab polar angle for all e+e- pairs | Lab polar angle for omega mesons | Lab polar angle for phi mesons |
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