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Here we report the performance of Glass gas electron multipliers (Glass GEMs), which were fabricated with photo-etchable glass. The photo-etchable glass used for substrate is called PEG3 (Hoya Corporation). With this material, we succeeded in fabricating a Glass GEM that was 680 μ m-thick with a hole diameter of 170 μ m and Cr and Cu layer electrodes. A Glass GEM has advantages such as good uniformity, high gain, a flat surface without stretching, cylindrical holes, and the absence of outgassing from the material. We successfully operated a Glass GEM having 100 × 100 m 2 effective area with various gas mixtures. The energy resolution for 5.9 keV X-rays was 18%, obtained by uniform irradiation of the entire effective area. The gas gain of the Glass GEM reached up to 90,000 with a gas mixture of Ne/C 4 (90:10). The Glass GEM was also operated with Ar/C 4 and Ar/C 4 gas. The gain stability measured for Glass GEM showed no significant increase or decrease as a function of elapsed time from applying high voltage. The gain stability over 15 hours of operation was about 10% in high-count-rate irradiation. Gain mapping across the Glass GEM showed good uniformity with a standard deviation of about 10%.

The temporal signals from a large gas detector may show dynamical scaling due to many correlated space points created by the charged particles while passing through the tracking medium. This has been demonstrated through simulation using realistic parameters of a Time Projection Chamber (TPC) being fabricated to be used in ALICE collider experiment at CERN. An interesting aspect of this dynamical behavior is the existence of an universal scaling which does not depend on the multiplicity of the collision. This aspect can be utilised further to study physics at the device level and also for the online monitoring of certain physical observables including electronics noise which are a few crucial parameters for the optimal TPC performance.Dynamical scaling refers here to powerlaw distribution or a powerlaw with an exponential cut-off that describes certain correlation phenomena in the dynamical systems distinctly being different from the random statistical processes. In the thermodynamical context, it describes a critical phenomena associated with the phase transition [1] while in many other complex systems it corresponds to the so called self organised criticality [2]. Although a powerlaw distribution (f ∼ x −β ) is a common dynamical feature, a powerlaw with an additional exponential (f ∼ x −β e −αx ) makes the distribution normalizable for all values of β (where α and β are positive constants) and also many real world systems like World Wide Web and social networks show this cut-off [3]. In this paper, we show the presence of both type of scalings, a powerlaw and a powerlaw with exponential in the temporal signals (comprising of time gap and bunch length distributions) of a large Time Projection Chamber (TPC) which is a type of gas detector used for three dimensional tracking of the charged particles passing through it during a particle physics experiment. The time gap distribution along the drift direction shows a dynamical scaling which is independent of the multiplicity of the collisions above a critical value. While this scaling behavior itself is an interesting aspect to investigate the correlation phenomena in a gas detector at the device level, it can be further utilised for online monitoring of certain important TPC parameters including the constant rise in electronics noise level due to long exposure to radiation.The TPC is the main tracking device of the ALICE (A Large Ion Collider Experiment) [4] at the Large Hadron Collider (LHC) at CERN optimized for the study of heavy ion collisions at a centre of mass energy ∼ 5.5 ATeV. It is a large gas filled detector of cylindrical design with an inner radius of about 80 cm, an outer radius of about 250 cm, and an over all length in the beam direction of 500 cm. A charged particle passing through the gas volume creates electrons by ionization. The electrons drift in the electric field towards the read out chambers (multiwire proportional counters with more than 550000 cathode pads read out located at the two end-caps of the TPC cylinder) where they are amplifie...

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