J.F. Martin

Construction and beam test of the ZEUS forward and rear calorimeter

Abstract The forward and rear calorimeters of the ZEUS experiment are made of 48 modules with maximum active dimensions of 4.6 m height, 0.2 m width, 7 λ depth and maximum weight of 12 t. It consists of 1 X 0 uranium plates interleaved with plastic scintillator tiles read out via wavelength shifters and photomultipliers. The mechanical construction, the achieved tolerances as well as the optical and electronics readout are described. Ten of these modules have been tested with electrons, hadrons and muons in the momentum range 15–100 GeV/ c . Results on resolution, uniformity and calibration are presented. Our main result is the achieved calibration accuracy of about 1% obtained by using the signal from the uranium radioactivity.

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

Test Beam Studies of a Silicon Microstrip Vertex Detector

We have built a working system of silicon microstrip detectors that achieves a single plane resolution better than 19 microns, a track efficiency close to 100% for normal incidence, and a noise rate of less than 10-3. This detector system meets the requirements for a microvertex detector in a high rate, fixed target environment.

Optical transition radiation monitor for the T2K experiment

Abstract An optical transition radiation monitor has been developed for the proton beam-line of the T2K long baseline neutrino oscillation experiment. The monitor operates in the highly radioactive environment in proximity to the T2K target. It uses optical transition radiation, the light emitted from a thin metallic foil when the charged beam passes through it, to form a two-dimensional image of the 30xa0GeV proton beam profile in the transverse plane. One of its key features is an optical system capable of transporting the light over a large distance out of the harsh environment near the target to a lower radiation area where it is possible to operate a camera to capture this light. The monitor measures the proton beam position and width with an accuracy better than 0.5xa0mm, meeting the physics requirements of the T2K experiment.

Cross sections for charm production by neutrinos

The production of charmed particles has been measured using a hybrid emulsion spectrometer in the Fermilab wide-band neutrino beam. The relative cross section for charged current charmed particle production is σ(v → μ−c)/σ(v → μ−) = 6.5 ±1.91.8%, and the energy dependence of the cross section is presented. One event with charm pair production was observed. A limit of σ(v → μcc)/σ(v → μc) < 6% (90% CL) is found for the ratio of charged current pair and single charm production.

A Recoil Proton Detector Using Cylindrical Proportional Chambers and Scintillator Counters

A recoil proton detector consisting of three cylindrical proportional wire chambers and four layers of segmented scintillator counters is described. The device measures the recoil trajectory and energy in the momentum transfer range 0.06 < − t(GeV/c)2 <1.4. It has been operated successfully at Fermilab as part of the Tagged Photon Spectrometer, where it was calibrated with protons in the data and was used to form a high mass diffractive trigger.

Study of the decays D r arrow K 3. pi

We report measurements of the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}, and {ital D}{sup 0}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup {minus}}{pi}{sup 0} from Fermilab photoproduction experiment E691. A complete resonant substructure analysis is used to determine the relative fractions and phases of amplitudes contributing to the decays {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}{pi}{sup +}{pi}{sup {minus}}, and {ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +}{pi}{sup 0}.

Study of the decays D r arrow K sup 0. pi. sup + and D r arrow K sup 0 K sup +

We report measurements of the decays {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +}, {ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +}, and {ital D}{sub {ital s}}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +} from Fermilab photoproduction experiment E691. The relative branching fractions obtained are {ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +})/{ital B}({ital D}{sup +}{r arrow}{ital K}{sup {minus}}{pi}{sup +}{pi}{sup +})=0.274{plus minus}0.030{plus minus}0.031, {ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +})/{ital B}({ital D}{sup +}{r arrow}{ital {bar K}}{sup 0}{pi}{sup +})=0.271{plus minus}0.065{plus minus}0.039, and {ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{ital {bar K}}{sup 0}{ital K}{sup +})/{ital B}({ital D}{sub {ital s}}{sup +}{r arrow}{phi}{pi}{sup +})=1.15{plus minus}0.31{plus minus}0.19.

A Study of the Semileptonic Decay Mode D0 ---> K- e+ Electron-neutrino

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).