K. Takikawa

The CDF central electromagnetic calorimeter

The central electromagnetic calorimeter for the Collider Detector at Fermilab uses a hybrid design with scintillator and wavelength shifter for energy measurement and an embedded strip chamber for position determination and longitudinal shower development. Complementary calibration systems are incorporated in the design. Calorimeter characteristics and performance are summarized. An average energy resolution, σ(E)E, of 13.5%√E sin θ (with E in GeV), and a position resolution of ±2 mm at 50 GeV are measured.

Intermediate silicon layers detector for the CDF experiment

Abstract The Intermediate Silicon Layers (ISL) detector is currently being built as part of the CDF II detector upgrade project. The ISL detector will significantly improve tracking in the central region and, together with the Silicon Vertex detector, provide stand-alone 3D track information in the forward/backward regions. In this article, we present the quality of the production sensors manufactured by Hamamatsu Photonics, which account for roughly half of the silicon sensors used in the ISL detector.

Proton computed tomography with a 250 MeV pulsed beam

Abstract Proton computed tomography (CT) has been performed using a 250 MeV pulsed beam. We developed a multiple-pencil-beam scanning method using a combination of moving slits for a reduction of the beam-scanning time. A magnetic spectrometer was used to measure the average energies of pulsed protons precisely. Position detectors have been developed to measure the centers-of-gravity of the multiple pencil beams at the image plane of the spectrometer. We obtained a 2-dimensional distribution of electron densities in a specimen within eight minutes by the method. We found that accurate information of the electron density was obtained by the method and that the density resolution was comparable with that of conventional X-ray CT.

Development of fiber-to-fiber connectors for scintillating tile/fiber calorimeters

Abstract We have developed fiber-to-fiber connectors for plastic fibers of 0.83, 0.90, and 1.00 mm in diameter. Such a connector is essential for detectors that use a large number of optical fibers, scintillating or clear. Typical applicators are unscintillating tile/fiber calorimetry and scintillating fiber tracking. We describe the design and performance of two types of small 10-fiber connectors which were developed for the CDF endplug tile/fiber calorimeter. The connectors showed a light transmission of 85–90% with a uniformity of 2.5–3.1%, and a reproducibility of 1%. Use of optical matching material at the joints could further improve the transmission and uniformity but showed instability after heat cycles.

A novel electromagnetic shower maximum position detector

Abstract We present test-beam results of a position sensitive electromagnetic shower-maximum detector consisting of 1 cm wide scintillator strips read out with wavelength shifting fibers. The detector is unique in that the strips are defined by deep “isolation” grooves carved in a single slab of scintillator. This novel design facilitates construction and results in reproducibly uniform detector elements. Operated at a depth of 6 radiation lengths inside an electromagnetic calorimeter, the detector yielded a position resolution of ±1.5 mm for 100 GeV electrons

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.

Beam test of radiation hardness of a scintillating tile/fiber calorimeter

Abstract Radiation hardness of a scintillating tile/fiber calorimeter is studied by irradiating electromagnetic test modules with 2.5 GeV electrons at the KEK linac. The induced damage is evaluated in a 2 GeV electron test beam by measuring the reduction in pulse height after irradiation. The pulse height peak for 2 GeV electrons is found to decrease by 19.3 ± 1.3% for a dose of 0.61 Mrad and 14.9 ± 2.7% for 0.33 Mrad. In addition to these modules, several tile/fiber assemblies were irradiated up to 4.8 Mrad and the damage as a function of dose was measured with a radioactive source. Effects of radiation damage on the linearity and energy resolution at higher energies are evaluated using a GEANT simulation and the measured damage.