Gas Electron Multipliers for the Antiproton Decelerator

The new beam profile measurement for the Antiproton Decelerator (AD) at CERN is based on a single Gas Electron Multiplier (GEM) with a 2D readout structure. This detector is very light (~0.4% X0), and measures horizontal and vertical profiles directly in one plane. This overcomes the problems previously encountered with multi-wire proportional chambers for the same purpose, where beam interactions with the detector severely affect the obtained profiles. A prototype was installed and successfully tested in late 2010, with another five detectors now installed in the ASACUSA and AEGIS beam lines. This paper will provide a detailed description of the detector and discuss the results obtained.Comment: Paper presented at DIPAC 2011, Hambur

A triple-GEM telescope for the TOTEM experiment

The TOTEM experiment at LHC has chosen the triple Gas Electron Multiplier (GEM) technology for its T2 telescope which will provide charged track reconstruction in the rapidity range 5.3<|eta|<6.5 and a fully inclusive trigger for diffractive events. GEMs are gas-filled detectors that have the advantageous decoupling of the charge amplification structure from the charge collection and readout structure. Furthermore, they combine good spatial resolution with very high rate capability and a good resistance to radiation. Results from a detailed T2 GEM simulation and from laboratory tests on a final design detector performed at CERN are presented.Comment: To appear in the proceedings of 10th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD06), Siena, Italy, October 1-5 200

The Strengthening Relationship between ENSO and Northeast Monsoon Rainfall over Sri Lanka and Southern India

Recently, it was reported that the relationship of the Indian southwest monsoon rainfall with El Niño–Southern Oscillation (ENSO) has weakened since around 1980. Here, it is reported that in contrast, the relationship between ENSO and the northeast monsoon (NEM) in south peninsular India and Sri Lanka from October to December has not weakened. The mean circulation associated with ENSO over this region during October to December does not show the weakening evident in the summer and indeed is modestly intensified so as to augment convection. The intensification of the ENSO–NEM rainfall relationship is modest and within the historical record but stands in contrast to the weakening relationship in summer. The intensification of the circulation is consistent with the warming of surface temperatures over the tropical Indian Ocean in recent decades. There is modestly intensified convection over the Indian Ocean, strengthening of the circulation associated with ENSO (Walker circulation), and enhanced rainfall during El Niño episodes in a manner consistent with an augmented ENSO–NEM relationship

Progress with diamond over-coated microstrip gas chambers

We describe recent observations and measurements with Micro-Strip Gas Chambers coated, after manufacturing, with a thin diamond-like layer in order to increase their rate capability. Compared to the more widely used solution consisting in coating the insulating support with a conductive layer before photo-lithography (the so-called undercoating), over-coating has the advantage of avoiding possible problems with adherence of metals to the layer, damages during the etching process and reduced quality of the artwork resulting from imperfections or dust inclusions in the layer. Early tests have however indicated that, possibly because of damages to the layer due to electron and ion bombardment during the avalanche process, irreversible structural modifications and fatal breakdown could be encountered at very high integral radiation fluxes. The present paper summarizes these results, and describes recent developments demonstrating that a better choice of the parameters of the over-coat may allow to withstand the radiation doses anticipated for LHC detectors with the intrinsically simpler over-coating solution. We discuss also several possible applications of the use of thin, controlled resistivity layers for other families of detectors used or in development for CERN¹s high luminosity collider

Development of high gain GEM detectors

We describe systematic measurements carried out with single and double GEM detectors with printed circuit readout. The maximum safe operating gain has been measured at increasing radiation flux and under exposure to heavily ionizing tracks. Detection efficiency, localization accuracy and cluster size have been measured in a minimum ionizing particle beam. With a suitably configured readout electrode, fast, two-dimensional localization of radiation is demonstrated. (15 refs)

Spherical GEMs for parallax-free detectors

We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical \textsc{gem}s are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This would eliminate the parallax error for detection of x-rays, neutrons or UV photons when a gaseous converter is used. This parallax error limits the spatial resolution at wide scattering angles. The method is inexpensive and flexible towards possible changes in the design. We show advanced plans to make a prototype of an entirely spherical triple-GEM detector, including a spherical readout structure. This detector will have a superior position resolution, also at wide angles, and a high rate capability. A completely spherical gaseous detector has never been made before.Comment: Contribution to the 2009 IEEE Nuclear Science Symposium, Orlando, Florid

Test of the two TOTEM TripleGEM Chambers assembled at G&amp;A Engineering

In this note we report the results of the tests performed at CERN on the two TOTEM TripleGEM chambers assembled by a private company

Development and test of large size GEM detectors

We discuss the main operating features of GEM detectors, optimized for use as trackers in a high radiation environment. The construction, tests and performances of large prototypes for the COMPASS experiment are also described, as well as the results of an exposure to very high intensity beams. (11 refs)

Optimization of operation and test of large size GEM detectors

We describe basic development work aimed at the realization of large (~1000 cm2 active) detectors for the COMPASS experiment, based on the gas electron multiplier technology. Essentially a high-rate forward spectrometer, the experiment requires high accuracy tracking of scattered particles and light detectors, in order not to degrade mass resolution and particle identification. The choice of a double GEM structure with two-coordinate read-out fulfils the above requirements. Systematic studies confirm the required performances, with good safety margins for an operation in harsh environments. We discuss the design problems encountered in the construction of the large devices and the solutions adopted, together with preliminary results obtained with prototypes in the laboratory and in a high intensity beam

Dina lineata (O.F. Müller, 1774) – an interesting species of leech in astatic reservoirs of the city of Olsztyn and its surroundings

The aim of the presently study was to provide information about the occurrence of Dina lineata in selected reservoirs of the city of Olsztyn and its surroundings. The material was collected applying the qualitative method. The leeches were found in the overflows of Olsztyn lakes (Skanda Lake and Redykajny Lake) and small astatic midfield reservoir near Samławki