In the framework of the uRANIA (u-Rwell Advanced Neutron Imaging Apparatus) project, we are developing innovative thermal neutron detectors based on resistive gaseous devices such as micro-Resistive ...WELL (μ-RWELL) and surface Resistive Plate Counter (sRPC).
The μ-RWELL is a single amplification stage resistive MPGD developed for HEP applications. The amplification stage, based on the same Apical® foil used for the manufacturing of the GEM, is embedded through a resistive layer in the readout board. The resistive layer is realized by sputtering the back side of the Apical® foil with DiamondLike-Carbon (DLC). A cathode electrode, defining the gas conversion/drift gap, completes the detector mechanics. The deposition of a thin layer of
10
B4C on the cathode surface allows the thermal neutrons conversion into
7
Li and α ions, which can be easily detected in the active volume of the device. Results from tests performed with different detector layouts show that a thermal neutron (25 meV) detection efficiency up to 7% can be achieved with a single detector. A comparison between experimental data and the simulation of the detector behaviour has been performed. In parallel, we are proposing the development of thermal neutron detectors based on a novel RPC concept. The sRPC is a revolutionary RPC based on surface resistive electrodes realized by exploiting the well-established DLC sputtering technology on thin (50µm) polyimide foils, the same used in the manufacturing of the µ-RWELL. The DLC foil is glued onto a 2 mm thick float-glass. The 2 mm gas gap between the electrodes is ensured by spacers made of Delrin®, inserted without gluing at the edges of the glass supports. By replacing DLC with
10
B4C sputtered electrodes, the device becomes sensitive to thermal neutrons. Different layouts of
10
B4C coated electrodes have been tested, allowing to achieve efficiency up to 6%. The robustness, ease of construction, and scalability of the sRPC technology should allow the construction of cost-effective large area detector units as required by applications in homeland security (such as Radiation Portal Monitor).
Micro Pattern Gas Detectors (MPGD) are the new frontier in gas trackers. Among this kind of devices, the Gas Electron Multiplier (GEM) chambers are widely used. The experimental signals acquired with ...the detector must obviously be reconstructed and analysed. In this contribution, a new offline software to perform reconstruction, alignment and analysis on the data collected with APV-25 and TIGER ASICs will be presented. GRAAL (Gem Reconstruction And Analysis Library) is able to measure the performance of a MPGD detector with a strip segmented anode (presently). The code is divided in three parts: reconstruction, where the hits are digitized and clusterized; tracking, where a procedure fits the points from the tracking system and uses that information to align the chamber with rotations and shifts; analysis, where the performance is evaluated (e.g. efficiency, spatial resolution,etc.). The user must set the geometry of the setup and then the program returns automatically the analysis results, taking care of different conditions of gas mixture, electric field, magnetic field, geometries, strip orientation, dead strip, misalignment and many others.
The experiment BESIII, running at the accelerator BEPCII in Beijing (P.R.C.), is going to be updated with the replacement of the Inner Drift Chamber with a Cylindrical triple-GEM Inner Tracker ...(CGEM-IT). In the R&D stage, two standalone C++ codes were implemented: GTS (Garfield-based Triple-GEM Simulator), for digitization and tuning of simulated data to the experimental ones, and GRAAL (GEM Reconstruction And Analysis Library), for the reconstruction and analysis of the experimental events collected in testbeams. GTS simulates the triple-GEM response to the particle passage, treating each stage separately: ionization, GEM properties, gas mixture, magnetic field and finally the induction of the signal on the anode. The necessary information was extracted by GARFIELD++ simulations, parametrized and used as input in GTS. This speeds up the simulation, since GTS performs only samplings instead of the full digitization chain. The simulated events were reconstructed with the same procedure used for experimental data and tuning factors were evaluated to obtain a satisfactory match. GRAAL is used in the analysis of the testbeam experimental data. It provides several levels of reconstruction: from the cluster formation, gathering contiguous firing strips, to the spatial position and the signal time reconstruciton. Two algorithms are used: the charge centroid and the micro-TPC, which exploit the charge deposition on the strips and the time information. Also a merging of the two algorithms is available to efficiently weight the two outcomes and obtain the best estimate of the spatial coordinate. Moreover, GRAAL performs tracking and alignment. Both codes are going to be made available also for other MPGDs simulation and reconstruction.
Triple-GEM detectors are a well known technology in high energy physics. In order to have a complete understanding of their behavior, in parallel with on beam testing, a Monte Carlo code has to be ...developed to simulate their response to the passage of particles. The software must take into account all the physical processes involved from the primary ionization up to the signal formation, e.g. the avalanche multiplication and the effect of the diffusion on the electrons. In the case of gas detectors, existing software such as Garfield already perform a very detailed simulation but are CPU time consuming. A description of a reliable but faster simulation is presented here: it uses a parametric description of the variables of interest obtained by suitable preliminary Garfield simulations and tuned to the test beam data. It can reproduce the real values of the charge measured by the strip, needed to reconstruct the position with the Charge Centroid method. In addition, particular attention was put to the simulation of the timing information, which permits to apply also the micro-Time Projection Chamber position reconstruction, for the first time on a triple-GEM. A comparison between simulation and experimental values of some sentinel variables in different conditions of magnetic field, high voltage settings and incident angle will be shown.
The IDEA detector concept has been designed to operate at a future large circular e+e− collider, like FCC-ee or CEPC. The IDEA detector has an innovative design with a central tracker enclosed in a ...superconducting solenoidal magnet. Going outwards, a preshower system followed by a dual readout calorimeter is foreseen. In the iron yoke, that closes the magnetic field, are then located three stations of muon detectors. The preshower and muon detectors are based on the μ-RWELL technology that inherits the best characteristics of the GEM, in particular the layout of the amplification stage, and Micromega detectors, that inspired the presence of a resistive stage. To profit of the industrial production capabilities of this technology, a modular design has been adopted for both systems: the μ-RWELL tile will have an active area of 50 × 50 cm2, but with a pitch between the readout strips of 400μm for the preshower and about 1 mm for the muon system. Other requirements are: a spatial resolution of the order of 100μm for the preshower and a reasonable total number of front-end channels for the muon system. To optimize the resistivity and the strip pitch, we have built a set of prototypes with active area of 5 × 40 cm2 and 40 cm long strips. The DLC resistivity is ranging from 10 to 80 MΩ/□. All these detectors have been exposed in October 2021 to a muon beam at the CERN SPS. The very positive results obtained pave the way for a completely new and competitive MPGD tracking device for high energy physics experiments.
Fatigue is a complex, subjective experience, frequent in multiple sclerosis (MS) and stroke patients. The tiredness these patients experience can take on many features depending not only on the ...cerebral location of the lesions and mood aspects, but also on the pathophysiology of the disease. Thus, it is reasonable to expect that fatigue may have different implications in MS and stroke. The aim of the present work was to compare fatigue syndrome in these two populations. Patients were matched for handicap.
Seventy-nine stroke and 39 MS outpatients were included with the following inclusion criteria: i) patients with possible or relapsing-remitting MS with an Expanded Disability Status Scale (EDSS) score<2.5, disease duration<6 years, and stable medical condition for at least 6 weeks; ii) stroke patients with mild neurological impairment, i.e. scoring<3 at the National Institute of Health Stroke Scale (NIHSS) one year after stroke; iii) absence of functional impairment (Barthel index=100) and similar negligible handicap (Rankin scale<2 for both groups); no or mild cognitive deficit; iv) neither DSMIV criteria of depression, nor significant anxious/depressive symptoms (Hospital Anxiety and Depression scale; HAD; score<8) in both groups. The Fatigue Assessing Instrument (FAI) was used to assess fatigue.
Twenty-nine percent of stroke and 46 p. cent of MS patients had a significant score on the FAI (p<0.05). Multiple regression analysis using groups, gender and age as factors showed a group effect in 3 out of 4 subscales: MS patients scored higher than stroke patients mainly for psychic impact (4.86 vs. 3.28), but also for severity (mean 3.86 vs. 2.97) and specificity (4.36 vs. 3.32). Response to rest (5.36 vs. 6.06) only tended to be better in the stroke group. In the subpopulation with significant fatigue scores, psychic impact was more elevated in the MS group. The functional consequence of fatigue in physical, professional and social activities were similar.
Fatigue was more severe in MS than stroke patients, independently of disability. The most significant factor in the MS group was the psychic impact, reflecting impaired motivation, concentration and irritability, despite the absence of depression. However, subjective consequences of fatigue on work, family and leisure activities were comparable in both groups.
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector operating on the Beijing Electron Positron Collider II (BEPCII). After more than ten years operation, the efficiency of the ...inner layers of the Main Drift Chamber (MDC) decreased significantly. To solve this issue, the BESIII collaboration is planning to replace the inner part of the MDC with three layers of Cylindrical triple Gas Electron Multipliers (CGEM).
The transverse plane spatial resolution of CGEM is required to be 120μm or better. To meet this goal, a careful calibration of the detector is necessary to fully exploit the potential of the CGEM detector. In all the calibrations, the detector alignment plays an important role to improve the detector precision. The track-based alignment for the CGEM detector with the Millepede algorithm is implemented to reduce the uncertainties of the hit position measurement. Using the cosmic-ray data taken in 2020 with the two layers setup, the displacement and rotation of the outer layer with respect to the inner layer is determined by a simultaneous fit applied to more than 160000 tracks. A good alignment precision has been achieved that guarantees the design request could be satisfied in the future. A further alignment is going to be performed using the combined information of tracks from cosmic-ray and collisions after the CGEM is installed into the BESIII detector.
PDF
