The Negative Ion Drift (NID) gas SF6 has favourable properties for track reconstruction in directional Dark Matter (DM) searches utilising low pressure gaseous Time Projection Chambers (TPCs). However, the electronegative nature of the gas means that it is more difficult to achieve significant gas gains with regular Thick Gaseous Electron Multipliers (ThGEMs). Typically, the maximum attainable gas gain in SF6 and other Negative Ion (NI) gas mixtures, previously achieved with an 55Fe X-ray source or electron beam, is on the order of 103 [1-4]; whereas electron drift gases like CF4 and similar mixtures are readily capable of reaching gas gains on the order of 104 or greater [5-9]. In this paper, a novel two stage Multi -Mesh ThGEM (MMThGEM) structure is presented. The MMThGEM was used to amplify charge liberated by an 55Fe X-ray source in 40 Torr of SF6. By expanding on previously demonstrated results [10], the device was pushed to its sparking limit and stable gas gains up to 50000 were observed. The device was further optimised by varying the field strengths of both the collection and transfer regions in isolation. Following this optimisation procedure, the device was able to produce a maximum stable gas gain of - 90000. These results demonstrate an order of magnitude improvement in gain with the NID gas over previously reported values and ultimately benefits the sensitivity of a NITPC to low energy recoils in the context of a directional DM search.

Low pressure gaseous Time Projection Chambers (TPCs) are a viable technology for directional Dark Matter (DM) searches and have the potential for exploring the parameter space below the neutrino fog. Gases like CF4 are advantageous because they contain flourine which is predicted to have heightened elastic scattering rates with a possible Weakly Interacting Massive Particle (WIMP) DM candidate. The low pressure of CF4 must be maintained, ideally lower than 100 Torr, in order to elongate potential Nuclear Recoil (NR) tracks which allows for improved directional sensitivity and NR/Electron Recoil (ER) discrimination. Recent evidence suggests that He can be added to heavier gases, like CF4, without significantly affecting the length of 12C and 19F recoils due to its lower mass. Such addition of He has the advantage of improving sensitivity to lower mass WIMPs. Simulations can not reliably predict operational stability in these low pressure gas mixtures and thus must be demonstrated experimentally. In this paper we investigate how the addition of He to low pressure CF4 affects the gas gain and energy resolution achieved with a single Thick Gaseous Electron Multiplier (ThGEM).

The Negative Ion Drift (NID) gas SF$_6$ has favourable properties for track reconstruction in directional Dark Matter (DM) searches utilising low pressure gaseous Time Projection Chambers (TPCs). However, the electronegative nature of the gas means that it is more difficult to achieve significant gas gains with regular Thick Gaseous Electron Multipliers (ThGEMs). Typically, the maximum attainable gas gain in SF$_6$ and other Negative Ion (NI) gas mixtures, previously achieved with an $^{55}$Fe X-ray source or electron beam, is on the order of $10^3$; whereas electron drift gases like CF$_4$ and similar mixtures are readily capable of reaching gas gains on the order of $10^4$ or greater. In this paper, a novel two stage Multi-Mesh ThGEM (MMThGEM) structure is presented. The MMThGEM was used to amplify charge liberated by an $^{55}$Fe X-ray source in 40 Torr of SF$_6$. By expanding on previously demonstrated results, the device was pushed to its sparking limit and stable gas gains up to $\sim$50000 were observed. The device was further optimised by varying the field strengths of both the collection and transfer regions in isolation. Following this optimisation procedure, the device was able to produce a maximum stable gas gain of $\sim$90000. These results demonstrate an order of magnitude improvement in gain with the NID gas over previously reported values and ultimately benefits the sensitivity of a NITPC to low energy recoils in the context of a directional DM search.

Direct searches for Weakly Interacting Massive Particle (WIMP) dark matter could greatly benefit from directional measurement of the expected induced nuclear recoils. Gas-based Time Projection Chambers (TPCs) offer potential for this, opening the possibility of measuring WIMP signals below the so-called neutrino floor but also of directional measurement of recoils induced by neutrinos from the Sun, for instance as proposed by the CYGNUS collaboration. Presented here for the first time are results from a Multi-Mesh Thick Gas Electron Multiplier (MM-ThGEM) using negative ion gases for operation with such a directional dark matter TPC. Negative ion drift gases are favoured for directionality due to their low diffusion characteristics. The multiple internal mesh structure is designed to provide a high gain amplification stage when coupled to future large area Micromegas, strip or pixel charge readout planes. Experimental results and simulations are presented of MM-ThGEM gain and functionality using low pressure pure CF 4 , SF 6 and SF 6 :CF 4 mixtures irradiated with alpha particles and 55 Fe x-rays. The concept is found to work well, providing stable operation with gains over 10 3 in pure SF 6 .

Recoil imaging entails the detection of spatially resolved ionization tracks generated by particle interactions. This is a highly sought-after capability in many classes of detector, with broad applications across particle and astroparticle physics. However, at low energies, where ionization signatures are small in size, recoil imaging only seems to be a practical goal for micro-pattern gas detectors. This white paper outlines the physics case for recoil imaging, and puts forward a decadal plan to advance towards the directional detection of low-energy recoils with sensitivity and resolution close to fundamental performance limits. The science case covered includes: the discovery of dark matter into the neutrino fog, directional detection of sub-MeV solar neutrinos, the precision study of coherent-elastic neutrino-nucleus scattering, the detection of solar axions, the measurement of the Migdal effect, X-ray polarimetry, and several other applied physics goals. We also outline the R&D programs necessary to test concepts that are crucial to advance detector performance towards their fundamental limit: single primary electron sensitivity with full 3D spatial resolution at the $\sim$100 micron-scale. These advancements include: the use of negative ion drift, electron counting with high-definition electronic readout, time projection chambers with optical readout, and the possibility for nuclear recoil tracking in high-density gases such as argon. We also discuss the readout and electronics systems needed to scale-up such detectors to the ton-scale and beyond.

Sensitivities of current directional dark matter search detectors using gas time projection chambers are now constrained by target mass. A ton-scale gas TPC detector will require large charge readout areas. We present a first demonstration of a novel ThGEM-Multiwire hybrid charge readout technology which combines the robust nature and high gas gain of Thick Gaseous Electron Multipliers with lower capacitive noise of a one-plane multiwire charge readout in SF6 target gas. Measurements performed with this hybrid detector show an ion drift velocity of 138 +/- 10 m s(-1) in a reduced drift field E/N of 93 x 10(-17) V cm(2) with an effective gas gain of 2470 +/- 160 in 20 Torr of pure SF6 target gas.

We demonstrate a new type of analysis for the DRIFT-IId directional dark matter detector using a machine learning algorithm called a Random Forest Classifier. The analysis labels events as signal or background based on a series of selection parameters, rather than solely applying hard cuts. The analysis efficiency is shown to be comparable to our previous result at high energy but with increased efficiency at lower energies. This leads to a projected sensitivity enhancement of one order of magnitude below a WIMP mass of 15 GeV c-2 and a projected sensitivity limit that reaches down to a WIMP mass of 9 GeV c-2, which is a first for a directionally sensitive dark matter detector.

Now that conventional weakly interacting massive particle (WIMP) dark matter searches are approaching the neutrino floor, there has been a resurgence of interest in detectors with sensitivity to nuclear recoil directions. A large-scale directional detector is attractive in that it would have sensitivity below the neutrino floor, be capable of unambiguously establishing the galactic origin of a purported dark matter signal, and could serve a dual purpose as a neutrino observatory. We present the first detailed analysis of a 1000 m$^3$-scale detector capable of measuring a directional nuclear recoil signal at low energies. We propose a modular and multi-site observatory consisting of time projection chambers (TPCs) filled with helium and SF$_6$ at atmospheric pressure. Depending on the TPC readout technology, 10-20 helium recoils above 6 keVr or only 3-4 recoils above 20 keVr would suffice to distinguish a 10 GeV WIMP signal from the solar neutrino background. High-resolution charge readout also enables powerful electron background rejection capabilities well below 10 keV. We detail background and site requirements at the 1000 m$^3$-scale, and identify materials that require improved radiopurity. The final experiment, which we name CYGNUS-1000, will be able to observe 10-40 neutrinos from the Sun, depending on the final energy threshold. With the same exposure, the sensitivity to spin independent cross sections will extend into presently unexplored sub-10 GeV parameter space. For spin dependent interactions, already a 10 m$^3$-scale experiment could compete with upcoming generation-two detectors, but CYGNUS-1000 would improve upon this considerably. Larger volumes would bring sensitivity to neutrinos from an even wider range of sources, including galactic supernovae, nuclear reactors, and geological processes.

The conceptual design of the experiment named CYGNO (a CYGNUs module with Optical readout) is presented here. CYGNO aims to make significant advances in the technology of single phase gas-only time projection chambers (TPC) for the specific application of rare scattering events detection. In particular it will focus on a read-out technique based on the GEM amplification of the ionisation and on the visible light collection with a sub-mm position resolution by sCMOS camera. This type of readout in conjunction with a fast light detection will allow to reconstruct three dimensional (3D) images of the recoiling particles with high precision, offering new ways to distinguish the electron and nuclear recoils. The recoil direction resolution is also being investigated as a further tool to reject neutral background in the detection of Galactic Dark Matter (DM) particles. The final goal is to build and operate a high resolution gas TPC detector at the 50 kg scale for the directional search of a DM signal, in underground Laboratori Nazionali del Gran Sasso. In order to achieve this very demanding goal, we are going to develop firstly a 1 m volume, 1 kg mass detector based on these concepts, to assess on a real underground experiment the design performances and capabilities of our approach, while at the same time testing innovative techniques and methods to reach the 50 kg scale. This project is part of the world-wide effort of the CYGNUS collaboration to define an optimal DM detection scheme sensitive to DM direction, towards a one-ton gas TPC nuclear recoils observatory. Published by Laboratori Nazionali di Frascati

The design of the project named CYGNO is presented. CYGNO is a new proposal supported by INFN, the Italian National Institute for Nuclear Physics, within CYGNUs proto-collaboration (CYGNUS-TPC) that aims to realize a distributed observatory in underground laboratories for directional Dark Matter (DM) search and the identification of the coherent neutrino scattering (CNS) from the Sun. CYGNO is one of the first prototypes in the road map to 100-1000 m^3 of CYGNUs and will be located at the National Laboratory of Gran Sasso (LNGS), in Italy, aiming to make significant advances in the technology of single phase gas-only time projection chambers (TPC) for the application to the detection of rare scattering events. In particular it will focus on a read-out technique based on Micro Pattern Gas Detector (MPGD) amplification of the ionization and on the visible light collection with a sub-mm position resolution sCMOS (scientific COMS) camera. This type of readout - in conjunction with a fast light detection - will allow on one hand to reconstruct 3D direction of the tracks, offering accurate sensitivity to the source directionality and, on the other hand, a high particle identification capability very useful to distinguish nuclear recoils.

Muon scattering tomography techniques can be used to image the contents of an enclosed volume by measuring the scattering angle of cosmic ray muons as they pass through a volume using particle tracking detectors. The magnitude of the observed muon scatter varies with the density of the objects within a volume, therefore the technique is well suited to distinguishing dense (high-Z) materials from lower density (low-Z) materials. AWE has been investigating muon scattering tomography techniques for use in the identification of special nuclear material (SNM) in transit cargo for a number of years. As part of this work AWE and our partner institutions have plate chamber technology, and a software suite of reconstruction tools and Monte Carlo simulations that we have used to quantify the capability and limitations of muon tomography techniques for SNM identification.Recent work at AWE has focused on the development of portable detector technologies for the imaging of objects and packages at unfixed locations. It is envisaged that portable detectors will be positioned to the sides of the screened objects rather than at the top and bottom with the object in the centre. This work has involved the further development of our Monte Carlo models to provide a more detailed of the horizontal muon flux and the implementation of new tracking algorithms to identify muons coming from either side of the tracking system. Part of this work has also involved investigating the use of portable wire chamber and silicon tracking detectors. Our work has also focused on examining the potential improvements to image quality afforded by the detection of spallation neutrons from muon interactions inside an object. The work presented will provide an overview of these recent developments and draw conclusions on the use of muon scattering tomography techniques for deployable security imaging applications.

This work presents data obtained from an investigation into muon stimulated neutron emission in combination with the technique of muon scattering tomography. Initial measurements in lead of the neutron emission measured a half-life of 56.9 ± 6.63 ns which is three standard deviations lower than expected, with the error primarily attributed to prompt X-ray emission. A hypothetical detector, based on a muon scattering tomography prototype at AWE was used to examine the data expected from an integrated system. A lifetime 81 ± 3 ns was obtained here. Alongside this a portable muon trigger detector has been developed which aims to be implemented in a deployable muon scattering tomography system. The portable detector successfully measures muons to an accuracy of 20%.

Current Data Grid tools are enhancing and getting more mature. On the other hand, several application users express their needs and requirements to deploy Grid tools in their daily work. Thus, there is a strong need that Grid tools make the transition from prototype tools to production tools. We have made several improvements and additions to an early release of the European DataGrid software tools in order to meet the requirements of data intensive sciences. We show that our software release is stable and performs well in order to be used in an international production infrastructure for physics data simulation with one High Energy Physics experiment. Furthermore, we outline the experience with interoperability solutions from the Grid Laboratory Uniform Environment (GLUE) activity. Published by SIS–Pubblicazioni Laboratori Nazionali di Frascati