Franco Bedeschi

The CDF Central and Endwall Hadron Calorimeter

Abstract The CDF central and endwall hadron calorimeter covers the polar region between 30° and 150° and a full 2π in azimuth. It consists of 48 steel-scintillator central modules with 2.5 cm sampling and 48 steel-scintillator endwall modules with 5.0 cm sampling. A general description of the detector is given. Calibration techniques and performance are discussed. Some results of the test beam studies are shown.

Detection of ultraviolet Cherenkov light from high energy cosmic ray atmospheric showers: a field test

Abstract We present the results of a test with a prototype apparatus aimed to detect the ultraviolet Cherenkov light in the wavelength range 2000–2300 A, emitted by high energy cosmic ray showers. The system consists of a gas proportional chamber, with TMAE vapour as the photosensitive element, placed on the focal plane of a 1.5 m diameter parabolic mirror. The test was done during the summer of 1989 with cosmic ray showers seen in coincidence with the EAS-TOP experiment, an extended atmospheric shower charged particle array now being exploited at Campo Imperatore, 1900 m above sea level, on top of the Gran Sasso underground Laboratory of INFN. The results were positive and show that a full scale ultraviolet Cherenkov experiment with good sensitivity, angular resolution and virtually no background from moonlight or even daylight can be envisaged.

A photosensitive chamber for cosmic-ray spectroscopy

Abstract We present details of the construction and performance of a set of photosensitive chambers intended to detect ultraviolet Cherenkov light in cosmic-ray shower experiments. The particularly simple design of these chambers allows mass production and outdoor operation. Detection efficiency and sensitivity to a few photoelectrons have been measured at the predicted level. Bench test results are shown and performances in true outdoor operation are presented.

Status report on CLUE

Abstract The CLUE experiment uses a new cosmic ray detector array planned to operate for the next decade. It utilises a MWPC chambers sensitive to UV, to image Cherenkov radiation produced in cosmic ray showers. This approach is unique in that the instrument is insensitive to skylight backgrounds, has a threshold similar to that of visible Cherenkov experiments but a longer duty cycle. These features make possible a class of interesting cosmic ray physics experiments. The CLUE experiment has started operation with two of the ten telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the same site as the HEGRA experiment. A description of the telescopes is given and some data on the tests performed are presented.

A method to measure the γ-ray content in VHE cosmic ray showers

Abstract An experimental technique is presented to determine the effectiveness of methods to tag photon initiated air showers and reject hadron initiated ones. The technique is based on the rate reduction in the Moon direction. With a photon energy threshold below or equal to 1 TeV, with an angular resolution of a few mrad and being insensitive to visible light, the proposed CLUE detector allows a wide and original physics program. In particular the direct measurement of the fraction of primary photons in the continuum of the cosmic ray flux is feasible with adequate statistics in a few months of data taking.

Position sensitive silicon detectors inside the tevatron collider

Abstract Four position sensitive silicon detectors have been tested inside the Tevatron beam pipe at Fermilab. The system is the prototype of the small angle silicon spectrometer designed to study primarily p p elastic and diffractive cross-sections at the Collider of Fermilab (CDF). Particles in the beam halo during p - p storage tests were used to study the performance of the detectors. Efficiency, linearity of response and spatial resolution are shown. Measurements performed at different distances from the beam axis have shown that the detectors could be operated at 8.5 mm from the beam with low rates and no disturbance to the circulating beams. This distance corresponds to about 11 times the standard half-width of the local beam envelope. The behaviour of the detectors with the radiation dose has also been investigated.

Construction and performance of silicon detectors for the small angle spectrometers of the collider detector of fermilab

Abstract The manufacturing process of a series of position sensitive silicon detectors is described together with the tests performed to optimize the performance of the detectors. The detectors are Schottky diodes with strips on the ohmic contract which allow to determine the position of the incoming ionizing particles by charge partition. Four detectors were assembled in a telescope and tested inside the vacuum pipe of the Tevatron Collider at Fermilab. The system is a prototype of the Small Angle Silicon Spectrometer, designed primarily to study p - p elastic and diffractive cross sections, and is a part of the Collider Detector of Fermilab (CDF). Several tests were performed to check the efficiency and the linearity of response of various regions of the detectors. Scans of the beam halo were also done both in high and low β optics to check how close to the beam the detectors could be operated. Finally, the dependence of the detector response on temperature and integrated radiation dose was investigated.

A test of dual readout with tiles for calorimetry

A small detector (6 radiation lenghts in total) divided into two sections of four times lead-quartz-scintillator tiles, each with a separate readout for Cerenkov and scintillation light has been tested. The results for high energy muons and electrons are presented. The measured Cerenkov light yield for electrons is about 50 C.p.e. per deposited GeV.

Measurement of the neutron fraction event-by-event in DREAM

We have measured the neutron fraction event-by-event in beam test data taken at CERN by the DREAM collaboration. I will review these measurements in the context of the importance of neutrons to future high-precision calorimetry, and bring together the data from SPACAL, the GLD compensating calorimeter, and DREAM to estimate the impact neutron fraction measurements will make on hadronic energy resolution in dual-readout calorimeters.