J. F. Martin

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).

Cross-sections for Neutrino Production of Charmed Particles

Abstract We have found 122 charmed-particle decays among 3855 neutrino interactions located in the fiducial volume of a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam. We obtain an average relative charmed-particle production cross section of σ(ν μ → c μ − ) σ(ν μ →μ − ) =4.9 −0.6 +0.7 % , at an average neutrino energy of 22 GeV. We also obtain a production rate of σ(ν μ → c c ν μ ) σ(ν μ →ν μ ) =0.13 −0.11 +0.31 % , if we assume that there was an undetected muon, a limit of σ(ν μ → c c μ − ) σ(ν μ → c μ − ) CL ) can be obtained. Other cross section ratios and limits are also presented.

TEST OF THE ZEUS FORWARD CALORIMETER PROTOTYPE

Abstract Four prototype modules following the same design as the ZEUS forward calorimeter (FCAL) modules have been constructed and tested with electrons, hadrons and muons in the momentum range of 1 to 100 GeV/ c . The main topics under investigation were: calibration, uniformity of response, noise, light yield, energy resolution and the electron to hadron response (e/h ratio). The result of the measurements is presented and the expected performance of the FCAL is discussed in the light of these results.

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

Measurement of the D+, F+, and Lambda(c)+ Charmed Particle Lifetimes

From the analysis of 685 neutrino and antineutrino interactions in an emulsion target, fifteen candidates for the multiprong decay of charged charmed particles are found. This Letter presents liketimes for the D/sup + -/, F/sup + -/, and ..lambda../sub c//sup +/ states based on the fitted events of the sample.

Experimental study of uranium plastic scintillator calorimeters

Abstract As a preparation for the ZEUS high resolution calorimeter, sampling calorimeters made from 3.2 mm plates of depleted uranium read out by plastic scintillator of 3 mm and 5 mm thickness have been built. The response of hadrons, electrons and muons has been measured in the energy range between 3 and 100 GeV. In agreement with predictions, the relative response of electrons and hadrons as well as the hadronic energy resolution depend strongly on the thickness of the plastic scintillator. For 3.2 mm depleted uranium and 3 mm thick scintillator we observe over the full energy range equal response for electrons and hadrons; a hadronic energy resolution of 34.5% E[ GeV ] is obtained. Results are given for the spatial resolution for electrons and hadrons. Finally, results from a lead scintillator calorimeter built as a prestudy before uranium plates were available are reported.

EXPERIMENTAL DETAILS ON LIFETIME MEASUREMENTS OF NEUTRINO PRODUCED CHARMED PARTICLES IN A TAGGED EMULSION SPECTROMETER

Abstract A new type of hybrid appaatus, which consisted of an emulsion target and a magnet spectrometer, was successfully used in an experiment to measure lifetimes of charmed particles produced by the wide-band neutrino beam from 350 GeV protons at Fermilab. The emulsion target was essential to find short distance decay vertices andthe counter spectrometer was used both to localize the neutrino events in the emulsion and also to identify the particles from weak decays and those produced in the neutrino interactions. Newly introduced emulsion techniques such as the changeable sheet as a low background interface to couple the emulsion target with the counter spectrometer, and the single track followback method to locate interaction and decay vertices in the emulsion, were proved to be very powerful. Details of the experimental apparatus and of the method of analysis employed are described.

Response of a uranium-scintillator calorimeter to electrons, pions and protons in the momentum range 0.5–10 GeV/c

Abstract We have exposed a sandwich calorimeter, consisting of 3.3 mm thick uranium pnterleaved with 2.6 mm thick scintillator tiles, to positive and negative electrons and pions and to protons in the momentum range of 0.5 to 10 GeV/c. We find that e/h is about 1 above 3 GeV/c, but decreases significantly for lower momenta. This ratio is the same for positive and negative pions and also for pions and protons of the same kinetic energy.

A Dalitz plot analysis of D ---> K pi pi decays

Decays of the [ital D][sup 0] meson to [ital K][sup [minus]][pi][sup +][pi][sup 0] and [ital [bar K]][sup 0][pi][sup +][pi][sup [minus]] and of the [ital D][sup +] to [ital K][sup [minus]][pi][sup +][pi][sup +] have been analyzed for resonant substructure. We present results on the amplitudes and phases of each decay mode and compare the results with other measurements. We confirm the highly nonresonant nature of the [ital D][sup +] to [ital K][sup [minus]][pi][sup +][pi][sup +] decays. There is general agreement with theoretical models for the branching ratios measured.