116847052
The LHCb RICH PMTs Readout Electronics and the Monitoring of the HPDs Quantum Efficiency
834378
Making spherical GEMs
We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap for x-rays can be formed. This would eliminate the parallax error in an x-ray diffraction setup, which limits the spatial resolution at wide diffraction 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 diffraction angles, and a high rate capability. A completely spherical gaseous detector has never been made before.
15634517
Progress on large area GEMs
In 2008, a triple GEM detector prototype with an area of ~ 2000 cm2 has been constructed, based on foils of 66 × 66 cm. GEMs of such dimensions had not been made before, and innovations to the existing technology were introduced to build this detector. This paper discusses these innovations and presents further work on large area GEM development. A single-mask technique overcomes the cumbersome practice of alignment of two masks, which limits the achievable lateral size. The holes obtained with this technique are conical, and have a so-called rim, a small insulating clearance around the hole in the substrate. Further refinements of this technique allow greater control over the shape of holes and the size of rims. Also, an improvement in homogeneity over large areas is expected. Simulation studies have been done to examine the effect of hole shape on the behavior of GEMs. Such studies can help understanding how to use new enhancements of the technique to optimize performance. Many potential applications for large area GEMs foresee large production volumes. Production issues have been studied, and single-mask GEMs turn out to be much more suitable for large scale production than standard GEMs.
35023217
First results of spherical GEMS
We developed a method to make gem foils with a spherical geometry. Tests of this procedure and with the resulting spherical gems are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This eliminates 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. Besides spherical gems, we have developed curved spacers to maintain accurate spacing, and a conical field cage to prevent edge distortion of the radial drift field up to the limit of the angular acceptance of the detector. With these components first tests are done in a setup with a spherical entrance window but a planar readout structure; results will be presented and discussed. A flat readout structure poses difficulties, however. Therefore we will show advanced plans to make a prototype of an entirely spherical double-gem detector, including a spherical 2d readout structure. This detector will have a superior position resolution, also at wide angles, and a high rate capability.
119804456
Multiplicity and energy trigger for a sampling electromagnetic calorimeter
Abstract We describe the trigger system for the electromagnetic calorimeter of the OBELIX experiment operating at the LEAR ring at CERN. The system has been studied mainly for multiplicity trigger on gamma rays, but energy and angular selections can also be performed. The designing criteria, the electronics performances, as well as the measured trigger capability to select some exclusive reactions are reported.