K. Lingel

Description and performance of the Fermilab E687 spectrometer

Abstract The magnetic spectrometer and charged particle tracking system used in Fermilab experiment 687 to study the photoproduction and decay of charm particles are described in detail. The photons are produced by a wideband electron beam which can operate at energies up to 600 GeV/ c . The spectrometer consists of a high resolution silicon microstrip detector, a large aperture dipole magnet, proportional chambers, a second large aperture dipole, and more proportional chambers. Three multi-cell threshold Cherenkov counters provide charged particle identification. The tracking system is capable of resolving the secondary decay vertices of charm and beauty mesons and baryons from the primary interaction vertex. It also determines the invariant mass of the multibody final states of particles containing heavy quarks with excellent resolution. The particle identification system allows one to identify kaons and protons present in these final states clearly. This collection of detectors produces very clean signals for charm particles and permits one to make many cross checks of the apparatus. The performance is illustrated for a variety of charm signals. Of particular interest is a description of the tracking through the silicon microstrip detector and its use in isolating downstream decay vertices. Two complementary approaches to the reconstruction of secondary decay vertices are presented and insight is gained by comparing their strengths and weaknesses.

A wide band photon beam at the Fermilab Tevatron to study heavy flavors

13 Present address: Vector Research Company, 6903 Rockledge Drive, Bethesda, MD 20817, USA . Present address : University of North Carolina-Asheville, Asheville, NC 28804, USA . Present address: STX Inc., 4400 Forbes Blvd ., Lanham, MD 20706, USA . Present address : University of Colorado, Boulder, CO 80309, USA . Present address : Fermilab, Batavia, IL 60510, USA. Present address : Dipartimento di Elettronica, University dl Pavia, Pavia, Italy. Present address : Dipartimento di Fisica Nucleate e Teorica dellUniversita and INFN Pavia, 1-27100 Pavia, Italy Present address : State University of New York, Stony Brook, NY 11794, USA. Present address : NIKHEF-H, 1009 DB, Amsterdam, The Netherlands . Present address : University of Alabama, Tuscaloosa, AL 35487, USA . Present address : Brandeis University, Waltham, MA 02254, USA. Present address : University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Present address : Nevis Labs, Columbia University, Irvington, NY 10533, USA.

Analysis of the decay mode D+ → K∗0μ+ν

Abstract Fermilab high-energy photoproduction experiment E687 provides a high statistics sample of the decay mode D + → K ∗0 μ + ν (charge conjugates are implied). Our analysis yields a branching ratio of Γ (D + → K ∗0 μ + ν) Γ (D + → K − π + π + ) = 0.56±0.04±0.06 . The ratios of the form factors governing the decay are measured to be R ν = 1.74 ±0.27±0.28 and R 2 = 0.78±0.18±0.10, implying a polarization of Γ l Γ t = 1.20±0.13 ±0.13 for the electron decay. Finally, we report new limits on the decay modes D + → K − π + μ + ν (nonresonent) and D + → K ∗0 π 0 μ + ν .

Analysis of the decay mode D+ ---> anti-K*0 mu+ neutrino

Abstract Fermilab high-energy photoproduction experiment E687 provides a high statistics sample of the decay mode D + → K ∗0 μ + ν (charge conjugates are implied). Our analysis yields a branching ratio of Γ (D + → K ∗0 μ + ν) Γ (D + → K − π + π + ) = 0.56±0.04±0.06 . The ratios of the form factors governing the decay are measured to be R ν = 1.74 ±0.27±0.28 and R 2 = 0.78±0.18±0.10, implying a polarization of Γ l Γ t = 1.20±0.13 ±0.13 for the electron decay. Finally, we report new limits on the decay modes D + → K − π + μ + ν (nonresonent) and D + → K ∗0 π 0 μ + ν .

A measurement of elastic J/ψ photoproduction cross section at Fermilab E687☆

Abstract Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.

Studies of DD correlations in high energy photoproduction

Abstract Analysis of data from the Fermilab high energy photoproduction experiment E687 for events containing fully and partially reconstructed pairs of charmed mesons is presented. Correlations from D D pairs are used to study production dynamics.

Measurement of Λ+c and D+s lifetimes☆

Abstract Measurements of the lifetimes of the Λ+c decaying into pK−π+ and of the D+s decaying into φπ+ are presented. The data were accumulated in the Fermilab Wide-Band photoproduction experiment E687. The lifetimes of the Λ+c and the D+s are measured to be (0.20±0.03±3)× 10−12s and (0.50±0.06±0.03) × 10−12s respectively.

Study of D0 → K−μ+ν in high energy photoproduction

Abstract We report a measurement of the semimuonic decay D0→K−μ+ν from data taken during the 1987–1988 fixed target run at Fermilab by the E687 Collaboration. We obtain Γ(D0→K−μ+ν)/Γ(D0→K−π+)=0.82±0.13±0.13 and use this result to calculate Γ(D 0 →K ∗− μ + ν)/Γ(D 0 →K − μ + ν)=0.59±0.10±0.13 .

Measurement of the decays D0 → π+π+π−π−, D0 → K−K+ and D+s → фπ+π+π−

Abstract We present measurements of the branching ratios for two Cabibbo suppressed decays of the D 0 meson, D 0 → π + π + π − π − and D 0 → K − K + , and for the decay D + s → фπ + π + π − . The physics signals were extracted from a data sample consisting of 60 million triggers, collected by Fermilab Photoproduction Experiment E687 from December 1987 to February 1988. The relative branching ratios are measured to be: Γ (D 0 → 4 π )/ Γ (D 0 → K3 π ) = 0.108±0.024±0.008, Γ (D 0 → KK)/ Γ (D 0 → K π ) = 0.138±0.027 ±0.010 and Γ( D s → ф3π)/Γ( D s → фπ) = 0.58±0.20±0.10 .

Measurement of the decays D0 → π+π+π-π-, D0 → K-K+ and D+ s → f{cyrillic}π+π+π-

Abstract We present measurements of the branching ratios for two Cabibbo suppressed decays of the D 0 meson, D 0 → π + π + π − π − and D 0 → K − K + , and for the decay D + s → фπ + π + π − . The physics signals were extracted from a data sample consisting of 60 million triggers, collected by Fermilab Photoproduction Experiment E687 from December 1987 to February 1988. The relative branching ratios are measured to be: Γ (D 0 → 4 π )/ Γ (D 0 → K3 π ) = 0.108±0.024±0.008, Γ (D 0 → KK)/ Γ (D 0 → K π ) = 0.138±0.027 ±0.010 and Γ( D s → ф3π)/Γ( D s → фπ) = 0.58±0.20±0.10 .