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.
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.
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.
59939504
THE LOW-FREQUENCY CHARACTERISTICS OF PSR J0437–4715 OBSERVED WITH THE MURCHISON WIDE-FIELD ARRAY
We report on the detection of the millisecond pulsar PSR J0437−4715 with the Murchison Wide-field Array (MWA) at a frequency of 192 MHz. Our observations show rapid modulations of pulse intensity in time and frequency that arise from diffractive scintillation effects in the interstellar medium (ISM), as well as prominent drifts of intensity maxima in the time–frequency plane that arise from refractive effects. Our analysis suggests that the scattering screen is located at a distance of ∼80–120 pc from the Sun, in disagreement with a recent claim that the screen is closer (∼10 pc). Comparisons with higher frequency data from Parkes reveal a dramatic evolution of the pulse profile with frequency, with the outer conal emission becoming comparable in strength to that from the core and inner conal regions. As well as demonstrating the high time resolution science capabilities currently possible with the MWA, our observations underscore the potential to conduct low-frequency investigations of timing-array millisecond pulsars, which may lead to increased sensitivity in the detection of nanoHertz gravitational waves via the accurate characterization of ISM effects.
1554579
Rapid Notification of TeV Transients with the Milagro Telescope
The Milagro telescope is a wide field of view TeV observatory that is ideally suited for the observation of transients in the 300 GeV–10 TeV band. Milagro has a very large field of view (about 2 sr), nearly continuous operation, and a fluence sensitivity that is comparable to satellite experiments. Milagro is currently performing real time searches for TeV transients, with the goal of prompt notification and multi‐wavelength observation of any detected TeV transients.
118278878
HI Structure Observations of Reionization and Dark Energy
The purpose of the talk was to review the current status of the Murchison Widefield Array (MWA), and show the applications of HI structure observations for both reionization and dark energy measurements. Since the status of the MWA is changing weekly, please see the website1 for the current status. This proceedings will instead concentrate on HI structure observations, their applicability to reionization and cosmography, and the implications for the SKA and future HI structure observations of dark energy.