113451453
Aging and conductivity of electrodes for high rate tRPCs from an ion conductivity approach
Resistive Plate Chambers (RPCs) are multipurpose ionizing gas detectors broadly used in Particle Physics research because of the outstanding time resolution they offer at a very affordable price, their robustness and their easy manufacture. However, to extend their use to a broader range of applications, some properties, specially the counting rate capability, need to be improved. The straightforward way to increase the rate capability is to develop new electrodes with resistivities in the range of 10 7 �10 8 .m offering, besides a “resistive” character, conductivity high enough for allowing faster charge depletion in the chamber. In this work, we have carried out electrical measurements on several materials that are currently used or, according to their conductivity values, are good candidates to be used as resistive plates in high rate RPCs. We have analysed their behaviour in order to identify and to better understand their conduction mechanisms and to determine the nature of the degradation processes.
120073980
Analysis of compact and sealed RPCs feasibility
In this article, the feasibility of developing compact and portable float glass sealed Resistive Plate Chambers, sRPCs, is analyzed. For this purpose, several small (80 cm 2 ) sealed chambers have been constructed using inexpensive materials like windows float glass, copper tape and nylon fishing line. For the sake of simplicity, during this first development stage, only R134a has been used as ionizing gas. In order to distinguish gas leakage from internal gas degradation, a couple of sRPCs were tested inside a box with flowing gas: one with R134a and another with N2. Prompt charge, signal rising slope and operational current were used to assess chambers performance degradation during a two-week period. Regarding these variables, small leakages were spotted as the main reason for the performance degradation observed after about one week of steady operation at the sRPC working in N2 environment. The sRPC working in an R134a environment did not show any significative degradation during the whole test. A discussion on merits and limitations of the proposed design is provided.
16249880
Performances of 4-gap timing RPCs for relativistic ions in the range Z=1-6
Results from 4-gap Resistive Plate Chambers (RPCs) under irradiation by fully stripped relativistic ions (normalized momentum p/M = γβ = 2.7, atomic charge Z = 1−6) are presented. A time resolution of 80 ps at high efficiency has been obtained by using standard `off the shelf' 4-gap timing RPCs from the new HADES time-of-flight wall. The resolution worsened to 100 ps for ~ 1 kHz/cm2 proton flux and for ~ 100 Hz/cm2 carbon flux. The chambers were operated at a field E = 100 kV/cm, showing a high stability during the measurements. It seems to exist ample room for improvement, in particular regarding the time resolution.
28772765
Conductivity and charge depletion aging of resistive electrodes for high rate RPCs
Development of new electrodes is a key element for the improvement of high rate Resistive Plate Chambers (RPC). In the particular case of resistive electrodes, the fabrication of these elements is a challenging problem from a material science point of view. The combination of resistivity, permittivity and stability requirements is really hard to satisfy for any known material. Only a few materials have been found to be suitable for fabrication of resistive plates. In this work, we have carried out electrical characterizations of some of the materials that are currently used in RPCs or are solid candidates to be used as resistive plates in high rate RPCs. As a result, we have found strong evidences that ion conduction processes under moderate to high electric fields are able to drift high amounts of charge which allow to understand the degradation nature of the involved processes.
160008925
Development of small easy to build and low gas consumming timing RPCs
Timing Resistive Plate Chambers (tRPCs) have become a very popular detectors due to the very good timing capability they offer for covering big surfaces at a very good performance/price ratio. However, such kind of detectors could also be very useful for small experimental setups as an alternative to other methods if their very bulky and uncomfortable gas system could be removed. They are not only very cheap, but they can be built very easily with very simple materials and a few fast electronic components. Recently, we have opened a research line aiming to develop small and portable sealed tRPCs (sRPCs) and to analyze the evolution of their performances along the time. As a first step, we built a few small one-gap and two-gap detectors and we installed in our laboratory a fast and reliable acquisition setup able to monitorize the main features of the detectors on real time. We tested some of the developed detectors under different environments and a comparison was made.
119242483
The Baryon Acoustic Oscillation Broadband and Broad-beam Array: Design Overview and Sensitivity Forecasts
This work describes a new instrument optimized for a detection of the neutral hydrogen 21 cm power spectrum between redshifts of 0.5 and 1.5: the Baryon Acoustic Oscillation Broadband and Broad-beam (BAOBAB) array. BAOBAB will build on the efforts of a first generation of 21 cm experiments that are targeting a detection of the signal from the Epoch of Reionization at z ~ 10. At z ~ 1, the emission from neutral hydrogen in self-shielded overdense halos also presents an accessible signal, since the dominant, synchrotron foreground emission is considerably fainter than at redshift 10. The principle science driver for these observations are baryon acoustic oscillations in the matter power spectrum which have the potential to act as a standard ruler and constrain the nature of dark energy. BAOBAB will fully correlate dual-polarization antenna tiles over the 600-900 MHz band with a frequency resolution of 300 kHz and a system temperature of 50 K. The number of antennas will grow in staged deployments, and reconfigurations of the array will allow for both traditional imaging and high power spectrum sensitivity operations. We present calculations of the power spectrum sensitivity for various array sizes, with a 35 element array measuring the cosmic neutral hydrogen fraction as a function of redshift, and a 132 element system detecting the BAO features in the power spectrum, yielding a 1.8% error on the z ~ 1 distance scale, and, in turn, significant improvements to constraints on the dark energy equation of state over an unprecedented range of redshifts from ~0.5 to 1.5.
7696311
Real-Time Calibration of the Murchison Widefield Array
The interferometric technique known as peeling addresses many of the challenges faced when observing with low-frequency radio arrays, and is a promising tool for the associated calibration systems. We investigate a real-time peeling implementation for next-generation radio interferometers such as the Murchison widefield array (MWA). The MWA is being built in Australia and will observe the radio sky between 80 and 300 MHz. The data rate produced by the correlator is just over 19 GB/s (a few peta-bytes/day). It is impractical to store data generated at this rate, and software is currently being developed to calibrate and form images in real time. The software will run on-site on a high-throughput real-time computing cluster at several tera-flops, and a complete cycle of calibration and imaging will be completed every 8 s. Various properties of the implementation are investigated using simulated data. The algorithm is seen to work in the presence of strong galactic emission and with various ionospheric conditions. It is also shown to scale well as the number of antennas increases, which is essential for many upcoming instruments. Lessons from MWA pipeline development and processing of simulated data may be applied to future low-frequency fixed dipole arrays.
14753206
Toward Epoch of Re-ionization Measurements with Wide-Field LOFAR Observations
This paper explores the potential for statistical epoch of re-ionization (EOR) measurements using wide field LOFAR observations. New developments in low frequency radio instrumentation and wide field signal processing allow very sensitive EOR measurements , and the analysis techniques enabled by these advances offer natural ways of separating the EOR signal from the residual foreground emission. This paper introduces the enabling technologies and proposes an analysis technique designed to make optimal use of the capabilities of LOFAR. In the absence of foreground contamination, the measurements we propose are more sensitive than others that have been discussed in the literature, with five 3-sigma power spectrum points in only 100 hours of observation with 4 MHz bandwidth for simple models of the high redshift 21 cm emissions. The challenge of residual foreground removal may be addressed by the symmetries inherent in the three-dimensional (two spatial frequencies and radiofrequency) nature of the radio interferometric data.
119849397
TRASGO: A proposal for a timing RPCs based detector for analyzing cosmic ray air showers
Abstract The study of the properties of primary cosmic rays with energies above 100 TeV is only accessible indirectly through the use of detector arrays at the Earth surface. Despite the extremely high multiplicity of the air showers produced in their interactions at the highest layers of the atmosphere, only a fraction of those particles arrive to the ground over surfaces from ∼ 0.1 to ∼ 100 km 2 . The lack of information on the primary interaction and the low density of particles at the detection plane make the event by event analysis very complicated and usually only mean analysis are possible, sometimes with the help of simulation programs. The necessity of covering big surfaces to gather a significant sample of information usually leads to the use of big volume detectors with limited performances, giving only access to a small part of the information carried out by the swarm of secondary particles of the shower. In this article, we propose the development of an affordable detector, the TRASGO, based on timing RPCs (Resistive Plate Chambers) offering at the same time very good timing and tracking performances. TRASGO would allow a better and more accurate reconstruction of the air shower properties either working stand-alone or in big surface arrays.