A Precision Measurement of the A-Dependence of Dimuon Production in Proton - Nucleus Collisions at 800 GeV/C
- Case Western Reserve U.
Precision measurements of the A-dependence of the reaction $$p + A. \to \mu^+ \mu^- + X$$ at 800 GeV /care reported in this thesis. Data were taken at Fermilab (E772) using a modified version of the large dimuon spectrometer in the ) Meson-East beamline. A total of 6 x $10^5$ muon pairs were recorded for targets of D, C, Ca, Fe, and W. The kinematic region spanned by the data corresponds to a dimuon invariant mass of $$3 \le M_{\mu^+ + \mu^-}$$ 14 GeV, a Feynman-x of $$-0.1 \le x_F \le 0.7$$ and a target parton momentum fraction of $$0.03 \le x_2 \le 0.30$$. Accurate relative target normalizations were achieved by careful monitoring of beam intensity and position, cyclic interchanges of targets; maintaining nearly 100% electronic lifetime, and by use of precisely fabricated targets. The systematic errors in the relative yields are less than 2% for all targets. Results are presented on the ratios of cross sections for nuclear targets relative to deuterium for the Drell-Y an process and for the production of the $$J/\upsilon$$ , $$\psi$$' , and $$\Upsilon$$ quarkonia. These ratios are presented as functions of variables $$P_{\tau}$$ and $$X_F$$ , and versus $$x_1$$ and $$x_2$$ for the Drell-Yan process. Nuclear depletion at low-$$x_2$$ is observed for the first time in the Drell-Yan process. No nuclear enhancement of the antiquark distribution is observed in the region $$x_2 \ge 0.1$$ . The data give tight constraints on models developed to explain nuclear medium effects in deep inelastic lepton scattering (EMC effect). Specifically, published models that have postulated a pion excess and 6-quark clusters are ruled out. The A-dependent behaviors on $$X_F$$ and $$P_{\tau}$$ for $$J/\psi$$ , $$\psi$$' , and $$\upsilon$$ production are also reported and compared with previous experiments. Substantial nuclear depletions are observed in both the $$X_F$$ and $$P_{\tau}$$ dependence. These depletions increase with increasing $$X_F$$ , and decrease with increasing $$P_{\tau}$$ .
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1426698
- Report Number(s):
- FERMILAB-THESIS-1991-25; UMI-92-02252; 324540
- Country of Publication:
- United States
- Language:
- English
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