A Study of $\ensuremathbox{\mathrm{J/\psi}}$ Production at
the LEP $\ensuremathbox{\mathrm{e^+ e^-}}$ Collider;
and
the Implementation of the
DELPHI Slow Controls System

Timothy John Adye
Lincoln College, Oxford

A thesis submitted for the degree of Doctor of Philosophy
at the University of Oxford
April 1998

A Study of $\ensuremathbox{\mathrm{J/\psi}}$ Production at
the LEP $\ensuremathbox{\mathrm{e^+ e^-}}$ Collider;
and
the Implementation of the
DELPHI Slow Controls System

Timothy John Adye
Lincoln College, Oxford

A thesis submitted for the degree of Doctor of Philosophy
at the University of Oxford
April 1998

Abstract

This thesis describes two separate areas of work conducted for the DELPHI detector at LEP.

The first concerns the Slow Controls of the DELPHI detector, which enable a single operator to oversee the proper functioning of the apparatus and to diagnose faults as they occur. The hardware and software of this system, as well as their interface to the experiment and the operator, are described. Some conclusions are drawn from seven years' design work and the initial six years' operation of DELPHI.

Secondly, a study is made of the production, at $\ensuremathbox{\mathrm{e^+ e^-}}$ collision centre of mass energies close to the $\ensuremathbox{\mathrm{Z^0}}$ resonance, of $\ensuremathbox{\mathrm{J/\psi}}$ mesons, decaying to $\ensuremathbox{\mu^+ \mu^-}$. $\ensuremathbox{\mathrm{J/\psi}}$ mesons produced via a B-hadron are used to measure the mean B lifetime,

$$\tau_{\ensuremathbox{\mathrm{B}}}= (1.53 \pm 0.11\ \ensuremathbox... ....)}} \pm 0.06\ \ensuremathbox{\mathrm{(syst.)}})\ \ensuremathbox{\mathrm{ps}}.$$

A measurement is also made of the fraction of $\ensuremathbox{\mathrm{J/\psi}}$s produced promptly at the $\ensuremathbox{\mathrm{e^+ e^-}}$ collision point,

$$\frac{N(\ensuremathbox{\mathrm{Z^0}}\ensuremathbox{\rightarrow}\m... ...\ensuremathbox{\mathrm{(stat.)}} \pm 1.2\ \ensuremathbox{\mathrm{(syst.)}})\%.$$

This method is largely model-independent.