We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate tracking of the associated electrons. When operated at suc
h a high pressure and in 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +-0.13 mm-sigma (longitudinal), 0.8 +-0.15 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent mixture. The TPC, that houses 1.1 kg of gas in its active volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8mm x 8mm x 1.2mm for approximately 10 cm/MeV-long electron tracks. This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the 0bbnu decay in 136Xe, specifically those based on novel gas mixtures. Therefore we ultimately focus on the calorimetric and topological properties of the reconstructed MeV-electron tracks.
We have recently reported the development of a new type of high-pressure Xenon time projection chamber operated with an ultra-low diffusion mixture and that simultaneously displays Penning effect and fluorescence in the near-visible region (300 nm).
The concept, dubbed `Penning-Fluorescent TPC, allows the simultaneous reconstruction of primary charge and scintillation with high topological and calorimetric fidelity.
Resistive gaseous detectors can be broadly defined as those operated in conditions where virtually no field lines exist that connect any two metallic electrodes sitting at different potential. This condition can be operationally recognized as no gas
gap being delimited by two metallic electrodes. Since early 70s, Resistive Plate Chambers (RPCs) are the most successful implementation of this idea, that leads to fully spark-protected gaseous detectors, with solid state-like reliability at working fields beyond 100kV/cm, yet enjoying the general characteristics of gaseous detectors in terms of flexibility, optimization and customization. We present a summary of the status of the field of resistive gaseous detectors as discussed in a dedicated closing session that took place during the XI Workshop for Resistive Plate Chambers and Related Detectors celebrated in Frascati, and especially we review the perspectives and ambitions towards the XII Workshop to be celebrated in Beijing in year 2014. Due to the existence of two specific reviews ([1,2]) also at this workshop, a minimum amount of overlap was found to be unavoidable. We have realized, however, that the three works provide a look at the field from different optics, so they can be largely considered to be complementary. Contrary to the initial concerns, the overall appearance seems to be fairly round, in our opinion.
We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range $f=0.1-3.5$GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-
times of signals originated in RPCs used for sub-100ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 meter scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to the intrinsic unbalance between the capacitive and the inductive coupling $C_m/C_o eq L_m/L_o$. A practical way to restore this symmetry has been introduced (hereafter `electrostatic compensation), allowing for a cross-talk suppression factor of around $times 12$ and a rise-time reduction by 200ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1GHz per 2 meter for typical float glass -based RPCs ($tan delta|_{glass} = 0.025pm0.005$). It is further shown that `electrostatic compensation can be achieved for an arbitrary number of strips as long as the nature of the coupling is `short-range, that is an almost exact assumption for typical strip-line RPCs. Evidence for deviations from the dominant TEM propagation mode has been observed, although they seem to have negligible influence in practical signal observables. This work extends the bandwidth of previous studies by a factor of almost $times 20$.
