The first applications of newly developed gaseous detectors with resistive electrodes for UV imaging in daylight conditions

Progress in the development of a S-RETGEM-based detector for an early forest fire warning system

“…One can see the resistive grid and the inner metallic strips Two slightly different designs of S-RETGEM were used in this work: one has a thickness of t=0.4 mm, a holes diameter of d=0.3mm, pitch p=0.8mm; and a strip width of w=0.4mm, the other one has t=0.8 mm, d=0.4mm, p=1mm, w=0.5mm. Both designs have an active area A of 10x10cm 2 and strips on one side orient perpendicular to the strip on the other side which offers a possibility of a two dimensional (2-D signal readout [14]) Note that S-RETGEM has several important advantages over the earlier version with un-segmented resistive electrodes named RETGEM (also used for the UV imaging purposes [6]). First, it is more robust due to the low capacity of strips; the energy released in occasional sparks is at least five times less than in RETGEM.…”

“…The gases used in this work were Ne+EF, Ne+10%CH 4 +EF, Ne+EF +air (various percentages) and pure ambient air saturated with EF vapors. Differing from the previous work [6] the EF vapors were introduced into the gas chamber by flushing carrier gas for about 30 sec through the bubbler filled with liquid EF and heated to 90°C. As will be subsequently revealed (see paragraph III.1d) this offers higher sensitivity at elevated ambient temperatures.…”

Comments to the paper by A. Peyaud et al., “The ForFire photodetector”

“…It seems therefore useful to provide the readers with the list of some earlier publications in which comparable or even higher sensitivity for flame detection were obtained using various detector designs (see for example [2][3][4][5][6][7][8][9][10][11]), including some that allow flame visualization and the determination of its position [3,[4][5][6][7][9][10][11].…”

First Tests of MICROMEGAS and GEM-Like Detectors Made of a Resistive Mesh

“…16 the ratio is about 0.4 which gives the quantum efficiency value at 185 nm (note that, due to the holes, the CsI coated surface is about 75% of the total area, thus the quantum efficiency of the coated area is respectively higher-18% at 185 nm which is close to one which can be achieved with metallic surfaces). The detection efficiency (D) of the mesh detector at 185 nm is: (5) and is at least 11%. It is very probable that at high gains the value of K reaches 100% (see [27]) and thus the expected D is around 14%.…”

“…In light of these theoretical and experimental facts, one can expect that in real experimental conditions, as such a long term high energy physics experiment, GEMs and MICROMEGAS will always have some probability of sparking. The problem of discharges becomes much more severe in the case of photosensitive micropattern detectors oriented on such applications as RICH or dark-matter cryogenic detectors (see for example [4] and references therein) or special UV imaging deices [5]: they have to operate at gains of or more so as to detect single photoelectrons and thus any radioactive background creating electrons per 0018-9499/$26.00 © 2010 IEEE event will cause breakdowns. Sustained efforts are focused on reducing this probability as much as possible and protecting detectors from damages by sparks.…”