M. S. Witherell

Study of the semileptonic decay mode D0-->K-e+ nu e.

We present an analysis of the exclusive semileptonic decay mode D/sup 0/ ..-->.. K/sup -/e/sup +/nu/sub e/. We have measured the ratio of decay rates GAMMA(D/sup 0/ ..-->.. K/sup -/e/sup +/nu/sub e/)/GAMMA(D/sup 0/ ..-->.. K/sup -/..pi../sup +/). After correcting for the reconstruction efficiencies and subtracting the contribution from other decay modes we have found the ratio to be equal to 0.77 +- 0.12(stat) +- 0.13(syst).

Measurement of Ds+/- and D+/- decays to nonstrange states.

Using the data from Fermilab experiment 691, we have observed signals for the decays D/sub s//sup +- / and D/sup +- /..--> pi../sup -/..pi../sup +/..pi../sup +- / and have analyzed these modes for the fraction due to rho/sup 0/..pi../sup +- / and f/sub 0/(975)..pi../sup +- /. In addition, we have searched for the decays D/sub s//sup +- / and D/sup +- /..--> pi../sup -/..pi../sup +/..pi../sup -/..pi../sup +/..pi../sup +- /. Values or upper limits are reported for the relative branching fractions for all of the above decays.

Experimental study of the semileptonic decay D+-->K-bar

The decay D/sup +/..-->..K/sup -/..pi../sup +/e/sup +/..nu../sub e/ has been studied in the Fermilab photoproduction experiment E691. The ratio of branching ratios, B(D/sup +/..-->..K-bar/sup *//sup 0/e/sup +/..nu../sub e/)/B (D/sup +/..-->..K/sup -/..pi../sup +/..pi../sup +/), is found to be 0.49 +- 0.04 +- 0.05, corresponding to a D/sup +/..-->..K-bar/sup *//sup 0/e/sup +/..nu../sub e/ branching ratio of (4.5 +- 0.7 +- 0.5)%. The branching ratio to the nonresonant (K/sup -/..pi../sup +/)/sub NR/e..nu../sub e/ final state is found to be less than 0.7% at the 90% confidence level. The K/sup *//sup 0/ mesons have a ratio of longitudinal to transverse polarization of 2.4/sub -0.9//sup +1.7/ +- 0.2. .AE

A general method of estimating physical parameters from a distribution with acceptance and smearing effects

Abstract A generalization of the maximum likelihood method of estimating physical parameters is presented which can be used when the data set has been distorbed by acceptance and smearing effects. This method employs events from a Monte Carlo simulation of the experiment directly in the calculation of the likelihood. It is sufficiently general that it can be used consistently, over any number of dimensions, and does not waste information contained in the data set. Systematic errors associated with this technique can be estimated and, if needed, reduced by including more Monte Carlo events.

Recebt results from the UCSB/LBL double beta decay experiment

Abstract A new limit has been set on neutrinoless double beta decay, a process which would require lepton number nonconservation, plus one other piece of new physics. That second item might be light Majorana electron neutrino mass, a very heavy Majorana neutrino, right-handed currents, or supersymmetric particles in theories with R-parity violation. Limits on all these quantities can be obtained from the result that the UCSB/LBL Ge multidetector system shows the halflife for 76 Ge → 76 Se + 2 e − to be > 1.2 × 10 24 y at the 90% confidence level or >2.4 × 1024y at the 68% confidence level.

Measurement of the D0, D+ and D(s)+ Lifetimes

We have measured the lifetimes of the D/sup 0/, D/sup +/, and D/sub s//sup +/ mesons which were produced by a high-energy photon beam incident on beryllium. Using the Fermilab Tagged Photon Spectrometer with a silicon-microstrip vertex detector we have collected 10/sup 8/ events from which we have extracted about 4200 D/sup 0/ decays in the K/sup -/..pi../sup +/ and K/sup -/..pi../sup +/..pi../sup -/..pi../sup +/ modes, 3000 D/sup +/ into the K/sup -/..pi../sup +/..pi../sup +/ channel, and a total of 230 D/sub s//sup +/ into phi..pi../sup +/ and K-bar/sup *//sup 0/K/sup +/. From an analysis of these events we have determined the lifetimes for the D/sup 0/, D/sup +/, and D/sub s//sup +/ to be 0.422 +- 0.008 +- 0.010, 1.090 +- 0.030 +- 0.025, and 0.47 +- 0.04 +- 0.02 psec, respectively

Development and construction of the SLD Cherenkov ring-imaging detector☆

Abstract We report on the development and construction of the Cherenkov ring-imaging detector (CRID) for the SLD experiment at the SLAC linear collider. In particular, we outline recent progress in the construction and results from testing the first components of the barrel CRID, including the drift boxes, liquid radiator trays and mirror system. We also review progress in the construction of the barrel CRID gas radiator vessel, the liquid radiator recirculator system, and the electronic readout system. The development of a comprehensive monitor and control system - upon which the stable operation and physics efficacy of the CRID depend — is also described.

Production of 400 mirrors with high VUV reflectivity for use in the SLD Cherenkov ring imaging detector

Abstract The Stanford Large Detector for experimental particle physics detection at the SLAC Linear Collider contains a Cherenkov ring imaging detector (CRID). The barrel CRID mirrors have been successfully produced and installed. The industrial mirror production process, the quality control of the mirrors produced, and the results of the vacuum ultraviolet (VUV) reflectivity and mirror-shape accuracy are described. An average reflectivity of at least 80% for light at 160 nm and 85% for light in the 180–230 nm wavelength range has been achieved in the production of over 400 mirrors of a typical size of 30 by 30 cm. The surface roughness and optical distortion measurements imply that the light loss due to scattering is a few percent of the incident light and the angular error due to shape distortion is less than 1 mrad.

Study of Ds+--> phie+ nu e and the absolute Ds+--> phi pi + branching fraction.

We have searched for the decay {ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}} in data from the Fermilab charm photoproduction experiment E691. The resulting upper limit is {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}}){lt}0.45{ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +}). Since the branching fraction for {ital D}{sub {ital s}}{sup +}{r arrow}{phi}{ital e}{sup +}{nu}{sub {ital e}} can be calculated from the measured branching fraction {ital B}({ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e}{sup +}{nu}{sub {ital e}}) to be (1.7{plus minus}0.3)%, this implies a 90%-confidence-level lower limit on {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +}) of 3.4%.

Monitor and control systems for the SLD Cherenkov ring-imaging detector

To help ensure the stable long-term operation of a Cherenkov Ring Imaging Detector at high efficiency, a comprehensive monitor and control system is being developed. This system will continuously monitor and maintain the correct operating temperatures, and will provide an on-line monitor of the pressures, flows, mixing, and purity of the various fluids. In addition the velocities and trajectories of Cherenkov photoelectrons drifting within the imaging chambers will be measured using a pulsed UV lamp and a fiberoptic light injection system.