T. Francke

Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors

Abstract The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique in determining the events “ t =0” as well as particle/photon separation in large mass TPC detectors filled with noble gases and/or condensed noble gases. The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap novel photosensitive gaseous detectors: wire counters, GEMs or glass capillary plates coupled with CsI photocathodes. We have performed systematic measurements with Ar, Kr and Xe gases at pressures in the range of 1–50xa0atm as well as some preliminary measurements with liquid Xe and liquid Ar. With the gaseous detectors we have succeeded in detecting a scintillation light produced by 22xa0keV X-rays with an efficiency close to 100%. We also detected the scintillation light produced by β’ s (5xa0keV deposit energy) with an efficiency close to 25%. Successful detection of scintillation from 22xa0keV X-rays open new experimental possibilities not only for nTOF and ICARUS experiments, but also in others, such as WIMPs search through nuclear recoil emission.

The cosmic-ray proton and helium spectra measured with the CAPRICE98 balloon experiment

A new measurement of the primary cosmic-ray proton and helium fluxes from 3 to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998. This experimental setup combines different detector techniques and has excellent particle discrimination capabilities allowing clear particle identification. Our experiment has the capability to determine accurately detector selection efficiencies and systematic errors associated with them. Furthermore, it can check for the first time the energy determined by the magnet spectrometer by using the Cherenkov angle measured by the RICH detector well above 20 GeV n � 1 . The analysis of the primary proton and helium components is described here and the results are compared with other recent measurements using other magnet spectrometers. The observed energy

A Novel UV Photon Detector with Resistive Electrodes

In this study we present first results from a new detector of UV photons: a thick gaseous electron multiplier (GEM) with resistive electrodes, combined with CsI or CsTe/CsI photocathodes. The hole type structure considerably suppresses the photon and ion feedback, whereas the resistive electrodes protect the detector and the readout electronics from damage by any occasional discharges. This device reaches higher gains than a previously developed photosensitive RPC and could be used not only for the imaging of UV sources, ames or Cherenkov light, for example, but also for the detection of X-rays and charged particles.

The PAMELA experiment in space

We provide in this paper a status report of the space experiment PAMELA. PAMELA aims primarily to measure the flux of antiparticles, namely antiprotons and positrons, in cosmic rays with unpreceden ...

Potential of RPCs for tracking

Abstract We have demonstrated that small gap (0.1–0.4xa0mm) RPCs made of low-resistivity materials ( ρ 8 xa0Ωxa0cm) can operate at counting rates of up to 10 5 xa0Hz/mm 2 with position resolutions better than 50xa0μm. Results of preliminary tests allow us to suggest a possible application of this new type of RPC for tracking.

The development of gaseous detectors with solid photocathodes for low-temperature applications

There are several applications and studies in fundamental research, which require the detection of VUV light at cryogenic temperatures. For these applications, we have developed and successfully tested special designs of gaseous detectors with solid photocathodes able to operate at low temperatures: sealed gaseous detectors with MgF2 windows and windowless detectors. We have experimentally demonstrated that both primary and secondary (due to the avalanche multiplication inside liquids) scintillation light can be recorded by photosensitive gaseous detectors. The results of this work may allow one to significantly improve the operation of some noble liquid TPCs.

Results from beam tests of the CAPRICE RICH detector

Abstract A compact RICH counter using a solid NaF radiator and pad readout has been developed and tested in particle beams. The good transmission of the optical elements together with a low noise level in the electronics results in a large number of detected photoelectrons per event. More than 20 photoelectrons are detected per event for Z = 1 particles with β > 0.9 at perpendicular incidence. The reconstructed Cherenkov angle has a resolution of 4.2 mrad at perpendicular incidence ( β = 0.9-1) and 19 mrad at 30° incidence angle. For light ions ( Z

High-rate, high-position resolution microgap RPCs for X-ray imaging applications

Abstract We have developed small prototypes (5×5 and 10×10xa0cm 2 ) of a new type of micropattern detector—a microgap RPC made of commercially available low resistivity ( ρ ∼10 4 –10 8 xa0Ωxa0cm) materials having a position resolution better than 50xa0μm FWHM and capable of operating at counting rates up to 10 7 xa0Hz/cm 2 . The main advantage of these detectors compared to traditional micropattern gaseous detectors is that they are spark protected. This may open a wide range of application in various fields, for example in medical imaging.

The successful operation of hole-type gaseous detectors at cryogenic temperatures

We have demonstrated that hole-type gaseous detectors, GEMs and capillary plates, can operate up to 77 K. For example, a single capillary plate can operate at gains of above 10/sup 3/ in the entire temperature interval between 300 until 77 K. The same capillary plate combined with CsI photocathodes could operate perfectly well at gains (depending on gas mixtures) of 100-1000. Obtained results may open new fields of applications for capillary plates as detectors of UV light and charge particles at cryogenic temperatures: noble liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic PETs.

High-energy deuteron measurement with the CAPRICE98 experiment

We report the first measurement of the deuterium abundance in cosmic rays above 10 GeV nucleon � 1 of kinetic energy. The data were collected by the balloon-borne experiment CAPRICE98, which was flown on 1998 May 28–29 from Fort Sumner, New Mexico. The detector configuration included the NMSU-WiZard/CAPRICE superconducting magnet spectrometer equipped with a gas RICH detector, a silicon-tungsten calorimeter, and a time-of-flight system. By combining the information from the spectrometer and the RICH detector, it was possible to separate deuterons from protons in the kinetic energy range from 12 to 22 GeV nucleon � 1 .I n order to estimate the proton background and the deuteron selection efficiency, we developed an empirical model for the response of the instrument, based on the data collected in this experiment. The analysis procedure is described in this paper, and the result on the absolute flux of deuterium is presented. We found that the deuterium abundance at high energy is consistent with the hypothesis that the propagation mechanism of light nuclei is the same as that of heavier secondary components. Subject headings: balloons — cosmic rays — Galaxy: abundances — ISM: abundances