Region Of Relativistic Rise Research Articles

Progress in [formula omitted] techniques used for particle identification

Particle identification techniques by measuring the specific energy loss dE dx have been widely used in high energy physics experiments for many years. The basics of the energy loss measurements are described briefly. The stability requirements, corrections and, in particular, the non-linear saturation effect are discussed in more detail. The performance of present large detectors such as resolution and particle separation power in the relativistic rise region are reviewed. Typical applications to various physics analyses at LEP are given.

A study of relativistic charged particle identification by primary cluster counting

Abstract The possibility to identify charged particles in the relativistic rise region by primary cluster counting in low-pressure gaseous detectors is discussed. Based on experimental parameters measured with a single detector module and with minimum ionizing electrons, the response of a full detection system to relativistic particles was simulated. Particle separation with a realistic device, comprising 20 consecutive detector modules, was evaluated in terms of total system length and momentum range. The estimated performance is compared to that of some existing d E d x detectors.

Progress in particle identification by ionization sampling

The present generation of large scale d E/d x detector was conceived in the mid-seventies. In fixed target physics applications (EPI, ISIS) the achieved particle identification efficiency allows for π/K separation in the relativistic rise region. In the family of compact colliding beam detectors (e.g. AFS, ARGUS, CLEO, JADE, TPC, UA1), only the LBL TPC performance was so far sufficient for operation beyond the minimum of ionization. New central detectors foreseen for experiments in near future (LEP) should be more performing and will require resolutions which are at the limits imposed by systematic higher order effects. Influence of various design parameters on the optimization of the d E/d x sampling performance is discussed, supported by recent result from measurements of full-scale detector segments and including tests using ionized tracks generated by pulsed UV lasers. Merits of longitudinal drift and fine sampling are compared to results obtained by classical charge integration.

Measurement of Ionization Loss in the Relativistic Rise Region with the Time Projection Chamber

We present here some results obtained with the LBL Time Projection Chamber (TPC) regarding the particle identification by the measurement of the ionization losses in the relativistic rise region. This includes the method of calibration using 55Fe sources, the measurement of the resolution using cosmic rays, which shows an equivalent K-? separation of 4.8 standard deviations at 3.5 GeV/c, and the preliminary results obtained with multihadronic events from e+e- annihilations.

Particle identification by dE/dx sampling in high pressure drift detectors

Abstract Resolution limits of large d E /d x sampling detectors were studied systematically for pressures up to 5.5 atm in a variety of argon mixtures. The measurements were performed in a detector consisting of 64 pairs of 2 × 2 cm 2 proportional counters and a 50 cm drift space. Resolving power and linearity of response were measured for several quasi-simultaneous particles at higher pressures, extending the total detector depth to 41 m of NTP equivalent. The results show that resolution is consistently reduced with respect to predictions based on atmospheric pressure measurements for depths up to 7.7 m without drift (EPI detector). Influence of second-order effects and critical parameters affecting the resolution are analyzed with emphasis on compact detector design and relativistic rise region.

Measurement of the ionization loss in the region of relativistic rise for noble and molecular gases

The ionization loss of relativistic charged particles has been measured in thin samples of Ar, Xe, and propane in a pressurized gas proportional counter. Although the total relativistic rise becomes smaller for increasing pressure, the reduced fluctuation of the ionization loss permits, in principle, a better particle separation. Propane is found, especially in the lower pressure range, to give better particle separation at the expense of restriction to smaller momenta in comparison to Ar and Xe. An attempt is made to describe the relativistic rise and particle identification by simple gas parameters using Sternheimer's approximation.

Particle identification in a large streamer chamber with reduced memory time

The feasibility of particle identification in the relativistic rise region was investigated in a streamer chamber with a memory time of about 1 μs. It was found that the magnitude of the relativistic rise of the ionization density remains in the presence of electronegative SF 6 gas. The accuracy of the ionization measurement with the automatic measuring system HPD is ±8% for 90 cm long tracks. This method looks promising to be used for particle identification in large scale experiments.

High energy particle identification by ionisation measurements using single gas proportional counter

A high pressure gas proportional counter is described, which has an ionisation resolution of 4% in the relativistic rise region up to 30–50 GeV/ c. The counter is 0.5 cm diameter and 120 cm long, aligned along the beam axis. It was designed for tuning and monitoring of separated bubble chamber beams using fast ejection. Results of beam tests at 5.46 and 8.25 GeV/ c show the statistical separation of protons and pions.