H. Miyata

CDF end plug electromagnetic calorimeter using conductive plastic proportional tubes

Abstract A 2.8 m diameter and 50 cm deep round disc-shaped calorimeter has been built for each of the forward and the backward opening of the central detector structure of the Collider Detector at Fermilab (CDF) using conductive plastic proportional tube arrays sandwiched with lead absorber panels. A thorough use of cathode readout based on pads and strips etched on the printed circuit boards on the chambers enabled us to construct a finely segmented projective tower geometry defined by a polar coordinate system with the origin at the center of the detector with minimum dead region. These modules were tested for various properties with high energy electron beams and completely mapped with 100 GeV electron beams. The response map was then used as the input for a χ 2 -minimization procedure and an improved uniformity of 1.3% rms was obtained. A factor of 500 to 1000 rejection of pions was obtained using a correlation matrix without relying on a momentum measurement.

Resistive plastic cathode for proportional chamber

Abstract Carbon mixed plastic tubes with high resistivity of 103-104 ωcm have been molded with an extrusion method and used for the dc cathode of a proportional counter and a multi-wire proportional chamber. The signal by gas multiplication was picked up from a strip rf cathode set outside the tube. The characteristics of the counter in the proportional mode have been studied with a gas of argon-isobutane mixture.

A gas sampling calorimeter using conductive plastic tubes (II)

Abstract A prototype module for the electromagnetic shower calorimeter has been constructed and its characteristics have been measured. It consists of 38 layers of planar proportional chambers interleaved with 3 mm thick lead plates. The proportional chamber is made of conductive plastic tubes as a dc cathode and pickup electrodes as an rf cathode. The pickup electrodes are copper-clad G-10 panels etched with finely segmented patterns which, when assembled, form complete conical towers. The module was tested using high energy electron and hadron beams of energy range from 25 GeV to 150 GeV. Energy resolution is 24% E( GeV ) , and the position resolution is 1.5 mm or better at and above 50 GeV. The lateral and longitudinal distributions of the energy deposit are studied and they are applied to π e discrimination.

A gas sampling calorimeter using conductive plastic tubes

Abstract Conductive plastic tubes are extruded, and used to construct planar proportional chambers as a sampling medium of electromagnetic showers. Pick-up electrodes of an arbitrary shape can be placed on both sides of the proportional chamber to read out induced signals from the wires. A prototype shower calorimeter, consisting of 32 layers of such chambers interleaved with lead plates of varying thickness is tested with high energy electron beams. Energy resolution, position resolution, linearity and π/e discrimination are all found to be quite satisfactory.

Measurement of the Polarization of \(\varLambda^{0}\) Hyperons Produced Inclusively by 12-GeV Protons on Tungsten

The polarization of 2.4×10 5 \(\varLambda^{0}\) hyperons has been measured in inclusive production by 12- GeV protons on tungsten at three production angles, 3.5°, 6.5°, and 9.5°. In terms of Feynmans x F and the transverse momentum p T of \(\varLambda^{0}\), the kinematic range is 0.3≦ x F ≦0.8 and 0.4≦ p T ≦1.6 GeV/c. The \(\varLambda^{0}\) was identified by detecting the proton and pion from the \(\varLambda^{0}{\rightarrow}p\pi^{-}\) decay with a double-stage magnetic spectrometer, and its polarization was determined from a hybrid Monte Carlo analysis on asymmetries in the angular distribution of the decay products. The observed polarization is consistent with the data obtained at higher energies, indicating that the phenomenon of the inclusive \(\varLambda^{0}\) polarization scales down to the 12-GeV region. The polarization at 12 GeV increases linearly with p T up to 16% at p T =1.0 GeV/c, showing a tendency to level off above that point.

High Energy Test of Conductive Plastic Proportional Tube Electromagnetic Calorimeter with Conical Tower Geometry

A prototype electromagnetic calorimeter module has been constructed using conductive plastic proportional tubes stacked with lead panels. Complete conical towers were formed by finely segmented pick-up electrodes etched on copper clad G-10 panels between which tube arrays were sandwitched. The module was tested by high energy electron and hadron beams up to 175 GeV. Excellent energy and position resolutions were obtained. Rejection of pions against electrons was studied.

Longitudinal Fluctuation of the Electromagnetic Cascade Showers Induced by 25, 50, 75, and 100 GeV Electrons

High energy behavior of the electromagnetic cascade shower has been studied. The high energy cascade showers were created by electron beams with energies of 25, 50, 75, and 100 GeV at Fermilab. The cascade showers were observed by a detector consisting of multi-layer lead plates and proportional chambers. The experimental results were analyzed with special emphasis on the fluctuation problem of the electromagnetic cascade shower. The formulation on the longitudinal cascade shower fluctuation is made in terms of the correlation matrix. Furthermore, the correlation matrix for the shower fluctuation is generalized to a continuous correlation function.

Time Variation of the Cosmic Ray Muon Flux in Underground Detectors and Correlation with Atmospheric Temperature

Time variations of the cosmic ray muon flux observed during the period from January 1987 to April 1990 in the Matsushiro underground muon observatory and the Kamiokande-II detector are compared. A significant correlation between the two observations is found. The observed variations are well explained as a temperature effect in the atmosphere based on precise atmospheric temperature measurements by the Wajima Observatory of the Japan Meteorological Agency.

Polarized Λ0 production at KEK

We have measured the polarization of Λ0 hyperons produced inclusively by 12 GeV protons on tungsten at KEK. For moderate xF (0.2≳xF≳0.7), the polarization is nearly independent of xF and increases roughly linearly with pT. As xF increases beyond 0.7, however, the polarization shows a significant xF dependence. Some preliminary data were taken on copper and beryllium targets. A future project on Σ0 polarization at KEK is indicated.

Study of Cascade Shower Fluctuation with a Tile/Fiber Sampling Calorimeter

We studied electromagnetic and hadronic longitudinal cascade shower fluctuations created by electron and pion beams with energies of 1, 2, 3, and 4 GeV at KEK. A prototype sampling calorimeter of lead and scintillator sandwich was constructed for future application in a linear collider and used for observing cascade showers. We investigated and formulated the behavior of fluctuations of electromagnetic and hadron showers using a correlation matrix with which we were able to separate the π 0 component in the hadron shower fluctuation. As an application, the relation between shower fluctuations and the energy resolution of the calorimeter has been studied.