A. Peisert

Progress in Cherenkov ring imaging: Part 1. Detection and localization of photons with the multistep proportional chamber

Abstract The multistep proportional chamber, operated with a photosensitive gas filling, makes it possible to obtain stable multiplication factors in excess of 106 and can be used for the detection of single photoelectrons released in the gas. The efficiency and localization properties of the device in the detection of vacuum ultraviolet photons are discussed here, in view of its use for particle identification exploiting the Cherenkov ring-imaging method.

High flux operation of the gated multistep avalanche chamber

Abstract A multiple gaseous detector based on the preamplification and transfer mechanism has been tested in a high radiation flux environment. The device, called the gated multistep avalanche chamber, can detect and localize with good space and time accuracies selected tracks in minimum ionizing particle fluxes exceeding 10 5 s −1 mm −2 . The general operation properties, as well as some of the problems encountered are discussed.

Progress in Cherenkov ring imaging: Part 2: Identification of charged hadrons at 200 GeV/c

Abstract We have used a ring-imaging Cherenkov detector to separate πs, Ks, and antiprotons in a 200 GeV/ c beam at Fermilab. This device was built as a prototype for a large-aperture counter now in operation in Fermilab experiment E605. The radiator consisted of 8 m of atmospheric-pressure helium gas. The photon detector was a multistep proportional chamber. Cherenkov photons near 8 eV were detected by photoionization of triethylamine (TEA) vapor in the chamber. An average of 2.5 to 2.7 Cherenkov photons were observed per event, corresponding to a figure of merit N 0 ⋍ 45 per cm. A single-photon radius uncertainty of 0.47 mm was obtained with a helium/TEA/CH 4 gas mixture in the photon detector. The rms uncertainty in the determination of the Cherenkov angle was ΔΘ c /Θ max = 0.006 , corresponding to one-standard-deviation π/K separation at 500 GeV/ c . At 200 GeV/ c , the particle identification efficiency in a beam containing 95.2% π − , 4.3% K − , and 0.5% antiprotons was 92% for the πs, 83% for the Ks, and 90% for the antiprotons.

Identification of large-transverse-momentum hadrons using a ring-imaging Cherenkov counter

Abstract We have constructed and operated a large-aperture ring-imaging Cherenkov counter in a large-transverse-momentum experiment at Fermilab. Approximately 3 photons per relativistic particle are emitted in helium gas, focused by spherical mirrors and detected by multistep proportional chambers using a He/TEA gas mixture. Hadron identification is obtained from threshold to approximately 200 GeV c .

Construction and Operation of a Large Ring-Imaging Cerenkov Detector

We have constructed a large-aperture ring-imaging Cerenkov counter, intended to identify high momentum hadrons in a high pt experiment at Fermilab (E605). To date we have performed a preliminary analysis on a small subset of our data, taken during the initial operation of our counter (April-June 1982). We have obtained ¿/K separation with good efficiency from about 60 GeV/c to 120 GeV/c in momentum under high luminosity conditions (~5 × 109 protons/second on target). Approximately 84% of all single-track events having at least one detected photon have been unambiguously identified. Cerenkov photons were detected by a multi-step avalanche chamber via the photoionization of triethylamine (TEA) vapor, and a mean number of 2.8 photons per event was detected for the highest velocity particles. Improvements in photon reconstruction are expected, especially as we refine our tracking procedures.

Cherenkov ring imaging using a television digitizer

Abstract A Cherenkov ring imaging device using as photon detector a multistep spark chamber coupled to a television digitizer is described. Results of a test run using triethylamine as photo-ionizing vapour are presented, as well as preliminary results obtained with a new vapour having an extremely low ionization potential.

Identification of 200 GeV/c Particles Using a Ring-Imaging Cherenkov Detector

A ring-imaging Cherenkov detector has been used to separate 7r, K-, and antiprotons in a 200 GeV/c test beam at Fermilab. The photon detector was a multistep avalanche chamberl with a proportional wire chamber as second stage. Cherenkov photons near 8 eV were detected by photoionization of triethylamine vapor (TEA) in the chamber. The radiator was 8 meters of atmospheric-pressure Helium gas. The ring image was formed in the entrance plane of the radiator by an 8-meter focal-length spherical mirror.

Advances in vacuum ultraviolet detection with multistep gaseous detectors and application to cerenkov ring imaging

The multistep avalanche chambers permits an efficient detection of VUV photons. In a two-step proportional mode charges higher than 1 pC are obtained from single electrons. By using as the final localization step a spark chamber viewed by a TV digitizer it is easy to have imaging of complex patterns. This is applied to Cerenkov ring imaging and (K,π) separation with 3σ up to 320 GeV is envisaged. The properties of various photo-ionizable vapours have been studied. By combining a scintillation xenon chamber with a photoionization wire chamber, a resolution of 8.3% (FWHM) has been obtained, by using tetrakis(dimethylamine)- ethylene vapour, for 5.9 keV X-rays.

Radiation hardness of Si strip detectors with integrated coupling capacitors

Si strip detectors with integrated coupling capacitors between diode and metallization and with separate bias resistors for each strip have been exposed to ionising radiation. Results from measurements of detector response before and after irradiation are presented. >

π/K/p identification with a large-aperture ring-imaging cherenkov counter

Abstract The operating large aperture ring-imaging Cherenkov detector from the FNAL experiment E605 is described. Cherenkov ultraviolet photons are detected with a multi-step avalanche chamber using a He/TEA gas mixture and π/K/p separation is obtained from 50 to 200 GeV/ c .