R. Loveless

Beam tests of the ZEUS barrel calorimeter

Abstract A fully compensating uranium—scintillator calorimeter was constructed for the ZEUS detector at HERA. Several of the barrel calorimeter modules were subjected to beam tests at Fermilab before shipping them to DESY for installation. The calibrations of the modules used beams of electrons and hadrons, measuring the uniformity of the response, and checking the resolution. The runs also provided opportunity to test a large fraction of the actual ZEUS calorimeter readout system in an integrated beam environment more than one year before HERA turn on. The experiment utilized two computer controlled mechanical structures, one of which was capable of holding up to four modules in order to study shower containment, and a magnetic spectrometer with a high resolution beam tracking system. During two running periods, beams of 6 to 110 GeV containing e, μ, π, and p were used. The results show energy resolutions of 35%/ E for hadrons and 19%/ E for electrons, uniformities at the 1% level, energy nonlinearity less than 1%, and equal response for electrons and hadrons.

Measurement of the CMS Magnetic Field

The measurement of the magnetic field in the tracking volume inside the superconducting coil of the Compact Muon Solenoid (CMS) detector under construction at CERN is done with a fieldmapper designed and produced at Fermilab. The fieldmapper uses 10 3-D B-sensors (Hall probes) developed at NIKHEF and calibrated at CERN to precision 0.05% for a nominal 4 T field. The precise fieldmapper measurements are done in 33840 points inside a cylinder of 1.724 m radius and 7 m long at central fields of 2, 3, 3.5, 3.8, and 4 T. Three components of the magnetic flux density at the CMS coil maximum excitation and the remanent fields on the steel-air interface after discharge of the coil are measured in check-points with 95 3-D B-sensors located near the magnetic flux return yoke elements. Voltages induced in 22 flux-loops made of 405-turn installed on selected segments of the yoke are sampled online during the entire fast discharge (190 s time-constant) of the CMS coil and integrated offline to provide a measurement of the initial magnetic flux density in steel at the maximum field to an accuracy of a few percent. The results of the measurements made at 4 T are reported and compared with a three-dimensional model of the CMS magnet system calculated with TOSCA.

A search for nucleon decay with multiple muon decays

Abstract A search was made for nucleon decays which result in multiple delayed muon decays using the HPW water Cerenkov detector. No contained events were found, which is consistent with the expected neutrino background of 0.7±0.2 events. Lower lifetime limits are calculated for eleven proton decay modes and five bound neutron decay modes, ranging from 2×10 30 yr to 1×10 31 yr.

Observation of short-lived particles produced in high energy neutrino interactions

Abstract Examination of a sample of 89 high-energy, neutrino-induced dilepton events produced in the Fermilab 15 ft bubble chamber has resulted in the direct observation of the production and visible semi-leptonic decay of short-lived particles. One charged decay, two neutral decays, and one decay candidate of undetermined charge are found. Assuming these events and the remaining dilepton signal result from D meson decays, we obtain τ D + = 2.5 −1.5 +3.5 × 10 −13 s and τ D 0 = 3.5 −1.7 +3.5 × 10 −13 s, using a maximum likelihood analysis.

Characteristics of a lead-scintillator calorimeter used to detect electron neutrinos

Abstract The response of a lead-liquid-scintillator calorimeter to electromagnetic and hadronic showers is reported. Operational characteristics, calibration, and the calculation of event energies are discussed. The hadronic resolution is measured to be 0.53 E ( GeV ) ; the electromagnetic resolution 0.27 E ( GeV ) . The charged current interactions of ν e have been identified by exploiting the difference in energy deposition along the beam direction for electron and hadron showers. The efficiency and effectivenes of the technique are discussed.

Design features and test results of the CMS endcap muon chambers

Abstract Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16 mm ) for the cathode-to-anode wire distance of 5 mm , the six-plane structure of these chambers yields a spatial resolution of about 80 μm , essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300 ns ) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is ∼4 ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25 ns . Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C / cm of the total accumulated charge.

The HPW proton‐decay experiment

The Harvard‐Purdue‐Wisconsin water Cherenkow proton‐decay detector is described. Running through early August, 1983, comprises 3.1×106 triggers at a 0.6 Hz rate, and 3.6×106 triggers at 0.7 Hz. Track reconstruction is demonstrated for cosmic‐ray muons. The apparatus records full data for as many as 7 delayed triggers occuring within 32 microseconds of the primary trigger or each other. Such delayed triggers have been used to calibrate the detector on electron‐decays of muons. We discuss the implications of delayed triggers for rapid recognition of certain classes of candidates for nucleon decay, and indicate the present sensitivity of the experiment.

New phenomena in ν interactions

Several events have been observed in neutrino interactions which have an e+ and a K°s decay in the final state along with the conventional μ−. A discussion of their detection and relation to dimuon events will be presented. The significance of the associated strange particles and related kinematic quantities will be discussed.

RESULTS FROM A FERMILAB NEUTRINO BEAM DUMP EXPERIMENT

The flux of prompt neutrinos from a beam dump has been measured in an experiment at the Fermi National Accelerator Laboratory (E613). Assuming that the charm production has a linear dependence on atomic number and varies as (1−‖×‖)5 e−2mT, a model dependent cross section of 27±5μb/nucleon can be derived. For neutrino energies greater than 20 GeV, the flux of electron neutrinos with respect to muon neutrinos is 0.78±0.19. For neutrinos with energy greater than 30 GeV and p⊥ greater than 0.2, the flux of νu compared to νμ is 0.96±0.22.

CSC Endcap Muon Chambers: design and test results

Presented are the main design features and performance results of the cathode strip chambers (CSCs) for the CMS Endcap Muon System. The six-plane structure of these chambers yields a spatial resolution of about 80 /spl mu/m, essentially uniform and independent of the strip width (up to 16 mm, which is unusually wide for the cathode-to-anode wire distance of 5 mm). In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300ns) is obtained using a simple network of comparators. The time resolution achieved at the trigger level is /spl sim/4ns (RMS) that allows unambiguous tagging of bunch crossing occurring every 25 ns. Aging tests, including those obtained with a recirculating gas system, showed only minor aging effects. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C/cm of the total accumulated charge.