The search for a novel technology able to detect and reconstruct nuclear and electron recoil events with the energy of a few keV has become more and more important now that large regions of high-mass dark matter (DM) candidates have been excluded. Moreover, a detector sensitive to incoming particle direction will be crucial in the case of DM discovery to open the possibility of studying its properties. Gaseous time projection chambers (TPC) with optical readout are very promising detectors combining the detailed event information provided by the TPC technique with the high sensitivity and granularity of latest-generation scientific light sensors. The CYGNO experiment (a CYGNus module with Optical readout) aims to exploit the optical readout approach of multiple-GEM structures in large volume TPCs for the study of rare events as interactions of low-mass DM or solar neutrinos. The combined use of high-granularity sCMOS cameras and fast light sensors allows the reconstruction of the 3D direction of the tracks, offering good energy resolution and very high sensitivity in the few keV energy range, together with a very good particle identification useful for distinguishing nuclear recoils from electronic recoils. This experiment is part of the CYGNUS proto-collaboration, which aims at constructing a network of underground observatories for directional DM search. A one cubic meter demonstrator is expected to be built in 2022/23 aiming at a larger scale apparatus (30 m3–100 m3) at a later stage.

The operation of a novel large area micro-patterned gaseous electron multiplier, made from a 125 micron thick copper claded kapton foil, the COBRA_125, is presented. The CO-BRA_125 is equiped with 3 independent electrodes which allow to establish 2 independent multiplication regions in a single micro-patterened gaseous electron mutiplier. We report on the operation of a COBRA_125 with an active area of 100×100 mm 2 . Charge gains above 10 4 and energy resolutions in the range 18%-20% were achieved in a mixture of Ar-CH 4 (90%-10%) by irradiation with X-rays from 55 Fe source. Gain and energy resolutions were stable over the detector area, with maximum deviation from the average values of 8% and 15%, respectively.

Present methods for quantitative X-ray phase analysis make extensive use of multilinear regression. Practical application of these methods compels workers to make a choice among many different sets of experimental conditions such as the number, identity and relative concentration of the phases in the synthetic mixtures used for the solution of the regression problem; the number and extent of the angular regions within which X-ray intensities are to be measured; and so on. There are as yet no general criteria for this selection, and classical statistical experimental methods, even such effective ones as SIMPLEX, are very time consuming. In the present work a Monte Carlo method is proposed for optimization of the reproducibility and detection limit for a completely general quantitative X-ray phase analysis. A system of three computer programs to this end is developed and applied to X-ray phase analysis of laterites, illustrating the choice of a set of performing conditions among 20 of them.

The operation of a Micropattern Gaseous Detector (MPGD) comprising a cascade of two non-standard Gas Electron Multipliers (GEM) made from a 100 µm kapton foil was evaluated in pure krypton and in krypton-CO 2 mixtures. The final avalanche charge was collected in a 2D strip readout, providing an active area of 10×10 cm 2 for the entire detection system. For each mixture, the effective gain and energy resolution were measured as a function of the electric field in the drift, transfer and induction regions. Using X-rays from a 55 Fe radioactive source (5.9 keV), gains close to 10 4 and energy resolution of 22% (FWHM) were achieved in pure krypton under stable conditions, showing the potential of the experimental setup for the following imaging studies.

A: A gaseous imaging detector based on a cascade of two non-standard gas electron multipliers (100 µm thick GEM) was operated in five different krypton-based mixtures and the achievable position resolution was determined. The micropattern gaseous detector (MPGD) has an active area of 10 × 10 cm 2 .The GEM foils are twice as thick as a standard GEM, being more robust to electric discharges and less prone to sparking-caused damage. Krypton, being the noble gas with the lowest value of intrinsic position resolution in the range 14-34 keV, is a good candidate for imaging applications based on gaseous detectors.Our measurements have confirmed that krypton-CO 2 mixtures showed an improvement in position resolution above 18 keV and up to 30 keV relatively to Ar-CO 2 mixtures. The MTF value at 10% in the energy range 22-24 keV was evaluated, being 0.5876(342) lp/cm for Ar-CO 2 (70:30) and a maximum of 3.2702(15) lp/cm for the Kr-CO 2 (90:10) mixture. K: Electron multipliers (gas); Gaseous imaging and tracking detectors; Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc); X-ray detectors 1Corresponding author.