Bogumił Konarzewski

Signal propagation in straw tubes with resistive cathode

The analysis presented in this paper is part of the research performed by the authors for the COMPASS experiment at CERN. We have developed a theoretical model of the signal transmission in a straw tube. In contrast to commonly used simplified models, our approach takes into account the energy losses in the cathode resistance. This model allows determination of the main electrical parameters, such as characteristic impedance and signal attenuation, as well as a detailed simulation of the pulse shape dependent on the point of the charge injection. Simulation results have been compared with the results of experimental measurements of different types of the straw detectors.

Transparency of the straw tube cathode for the electromagnetic field

The analysis of the influence of foil straw tube cathode construction on their electrical parameters is presented. The model of cathode impedance, which allows estimation of the influence of cathode material (type of a foil) and construction (the way of foil strips winding) on signal transmission and electromagnetic interference immunity, is shown.

A Simple Method of Determining the Effective Attenuation Coefficient

A Simple Method of Determining the Effective Attenuation Coefficient This paper presents a simple method of determining the effective attenuation coefficient from steady-state diffuse reflectance measurements.

Single Photon Counting System for Biomedical Applications

Single photon counting system for biomedical applications was designed and tested. Examination of changes of an optical signal on a patients head during stimulation tests (finger taping) was made by the elaborated system.

DEAD TIME MEASUREMENT BY TWO-SOURCE METHOD – OPTIMIZATION OF MEASUREMENT TIME DIVISION

The article presents the analysis of the dead time measurement using two sources for a non-paralyzable detector. It determined the optimum division of count rate measurement time between both source measurement and a single source one. Results of the work can be used to optimize dead time measurement for systems which count photons or particles.

NEEDLE DETECTOR OF X-RAY AND GAMMA RADIATION

The article presents the developed structure of the novel needle proportional gas detector (NPC – Needle Proportional Counter) used for the detection of X-rays and gamma rays. The advantage of the detector is its simple mechanical construction and the possibility of detection of incident radiation in a direction parallel to the needle. The measured energy spectrum of the isotope Fe-55 by means of the developed detector is presented.

Fully Automated Machine for Scanning SIMP detectors

A fully automated measurement system has been built to measure uniformmity of the parameters of SiPM detectors with very high pixel densities. It has a light source with a microfocus spot (FWHM = 3 μm at the detector surface) and a precise positioning system (1 μm accuracy). A temperature control system with water cooling has been used to set the temperature of the measured detector. Finally, a low noise, custom made front-end amplifier has been designed to receive SiPM signals. This paper presents the MAPD-3N detector measurement results uniformity of gain and relative photon detection efficiency (PDE).

An automated system for scanning micropixel avalanche photodiodes with a fast amplifier

Silicon Photomultipliers (SiPMs) are rapidly developing photosensitive devices which are already used as an alternative to photomultipliers (PMT) in the newly developed calorimeters for high-energy physics. Many measurement results and SIPMs parameters based on signal amplitude histograms analysis have been published. Author presents a special automated system for scanning SIPMs surfaces with a fast amplifier. The system has been developed in order to examine shape of signal response dependency on position of photons hits on the surface of the detector.

Construction, performance and modeling of a compact SciFi hodoscope for use in detector testing at various test beams

It is quite common practice to test detectors for high energy physics experiments using test beams, produced at various accelerator facilities. A key component of every test setup is a trigger system, which usually has to be provided by the team preparing the test. Therefore, a compact scintillating fiber detector has been built, with the aim of working as a position sensitive trigger device for testing Shashlyk-type modules of a new electromagnetic calorimeter (ECAL0), being built for the COMPASS experiment. A description of the construction of the detector is presented, followed by its performance evaluation using a low-intensity electron beam from the ELSA accelerator and electrons at the T10 test beam in CERN. The detector was adapted for use with acquisition system based on an 80 MSPS, 12-bit analog-to-digital converters. An effort has been made to develop a full Monte-Carlo model of the system, which includes simulation of particle interactions, detector optics, photomultiplier, signal acquisition electronics (both ADC and shaping, incl. noise simulation) and finally signal quantization, ADC non-linearity and its clock jitter.

Results of measurements of photodetectors for the ECAL0 calorimeter for the COMPASS-II experiment

Silicon Photomultipliers (SiPMs) are rapidly developing photosensitive devices which are already used as an alternative to photomultipliers (PMT) in the newly developed calorimeters for high-energy physics. Nevertheless, they do have some disadvantages, namely relatively high noise and limited dynamic range, which is caused by a fixed number of pixels. Two types of SiPMs with a very high pixel density have been measured in order to select photosensor for a new electromagnetic calorimeter being built for the COMPASS-II experiment in CERN. The two candidates were: Zecoteks Micropixel Avalanche Photo Diode MAPD 3N and Hamamatsu Multi-pixel Photon Counter (MPPC) S12572-010P. This paper presents a dedicated measurement system designed to measure SiPMs response to short light pulses, followed by measurements of the parameters of the above sensors at various temperatures and operating voltages. The results cover measurements of the gain, relative photon detection efficiency, correlated noise and dark rate. Furthermore, breakdown voltage and its dependency on temperature of both detectors is shown. The final results present the useful range of operating conditions and the comparison of signal to noise ratio of the two devices.