Gas Time Projection Chamber Research Articles

Front-End Electronics for the SiPM-Readout Gaseous TPC for Neutrinoless Double-Beta Decay Search

We have developed a dedicated front-end-electronics board for a high-pressure xenon gas time projection chamber for a neutrinoless double-beta decay search. The ionization signal is readout by detecting electroluminescence photons with SiPM's. The board readout the signal from 56~SiPM's through the DC-coupling and record the waveforms at 5 MS/s with a wide dynamic range up to 7,000 photons/200 ns. The SiPM bias voltages are provided by the board and can be adjusted for each SiPM. In order to calibrate and monitor the SiPM gain, additional auxiliary ADC measures 1 photon-equivalent dark current. The obtained performance satisfies the requirement for a neutrinoless double-beta decay search.

Development of a low-[formula omitted]-emitting [formula omitted]-PIC as a readout device for direction-sensitive dark matter detectors

Direction sensitivity could provide robust evidence for the direct detection of weakly interacting massive particles constituting dark matter. However, the sensitivity of this method remains low due to the radioactive backgrounds. The purpose of this study is to develop a low-background detector as a two-dimensional imaging device for a gaseous time projection chamber. In direction-sensitive dark matter experiments (e.g. NEWAGE), α-rays emitted from the detector components often create substantial radioactive backgrounds. Based on the study of the background of NEWAGE, a new detector “low-αμ-PIC” is developed. The produced μ-PIC performs well as a gas detector and the α-ray emission rate from the μ-PIC reduced by a factor of 100.

Conceptual Design of DUNE Near Detector Superconducting Magnet System

The Deep Underground Neutrino Experiment (DUNE) formed a near detector design group (NDDG) which was tasked with delivering a CDR by the end of 2019. The DUNE Near Detectors will be housed in an underground hall on the Fermilab site. The two main detector systems are a liquid argon detector and a high-pressure gas time projection chamber (HPgTPC). The HPgTPC requires a magnet that generates a 0.5 T solenoidal magnetic field in a large volume of 6 m diameter, and 5 m length. In this paper, we present a superconducting magnet system design. We investigated: an open air core magnet with three coils, and a five-coil s system having two active fringe field shielding coils. Coils positions were optimized to obtain the specified field homogeneity in the magnet good field region, while minimizing the Lorentz forces and the superconductor volume. We discuss the magnetic, mechanical, and thermal conceptual designs.

Design and performance of a high-pressure xenon gas TPC as a prototype for a large-scale neutrinoless double-beta decay search

Abstract A high-pressure xenon gas time projection chamber, with a unique cellular readout structure based on electroluminescence, has been developed for a large-scale neutrinoless double-beta decay search. In order to evaluate the detector performance and validate its design, a 180 L size prototype is being constructed and its commissioning with partial detector has been performed. The obtained energy resolution at 4.0 bar is 1.73 $\pm$ 0.07% (FWHM) at 511 keV. The energy resolution at the $^{136}$Xe neutrinoless double-beta decay $Q$-value is estimated to be between 0.79 and 1.52% (FWHM) by extrapolation. Reconstructed event topologies show patterns peculiar to the track endpoint that can be used to distinguish $0\nu\beta\beta$ signals from gamma-ray backgrounds.

Topological background discrimination in the PandaX-III neutrinoless double beta decay experiment

The PandaX-III experiment plans to search for neutrinoless double beta decay (0νββ) of 136Xe in the China JinPing underground Laboratory (CJPL). The experiment will use a high pressure gaseous time projection chamber (TPC) to register both the energy and the electron track topology of an event. This article is devoted to demonstrate our particular detector setup capabilities for the identification of 0νββ and the consequent background reduction. As software tool we use REST, a framework developed for the reconstruction and simulation of TPC-based detector systems. We study the potential for background reduction by introducing appropriate parameters based on the properties of 0νββ events. We exploit for the first time not only the energy density of the electron track-ends, but also the electron scattering angles produced by an electron near the end of its trajectory. To implement this, we have added new algorithms for detector signal and track processing inside REST. Their assessment shows that background can be reduced by about 7 orders of magnitude while keeping 0νββ efficiency above 20% for the PandaX-III baseline readout scheme, a two-dimensional 3 mm pitch stripped readout. More generally, we use the potential of REST to handle 2D/3D data to assess the impact on signal-to-background significance at different detector granularities, and to validate the PandaX-III baseline choice. Finally, we demonstrate the additional potential to discriminate surface background events generated at the readout plane in the absence of t o , by making use of event parameters related with the diffusion of electrons.

Drift field generation with Cockcroft-Walton voltage multiplier in xenon gas for AXEL 0vββ search detector

For noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC.

The NEXT experiment for neutrinoless double beta decay searches

NEXT is an experiment to search for the neutrinoless double beta decay of 136Xe using a high pressure xenon gas time projection chamber. This detector technology has several key advantages, including excellent energy resolution, powerful event classification based on track topology, and favorable mass scalability. The current stage of the experiment, NEXT-White, has been taking data at the Canfranc Underground Laboratory (LSC) in Spain since late 2016. In this talk, we will review recent results from NEXT-White after the first year of low-background operations with both 136Xe-depleted and 136Xe-enriched xenon gas. Background measurements will be shown as well as preliminary results on the two-neutrino mode double beta decay.

PandaX-III: Searching for Neutrinoless Double Beta Decay with High Pressure Gaseous Time Projection Chambers

The PandaX-III (Particle And Astrophysical Xenon Experiment III) experiment will search for Neutrinoless Double Beta Decay (NLDBD) of 136Xe at the China Jin-Ping underground Laboratory II (CJPL-II). In the first phase of the experiment, a high pressure gas Time Projection Chamber (TPC) will contain 200 kg, 90% 136Xe enriched gas operated at 10 bar. Microbulk Micromegas, a fine pitch micro-pattern gas detector, will be used for charge readout and enable us to reconstruct tracks of NLDBD events with good energy and spatial resolution. With simulation, we demonstrate excellent background suppression capability with tracking information. In this proceeding, we will give an overview of recent progress of PandaX-III, including data taking of a 20 kg scale prototype TPC.

Status of the TREX-DM experiment at the Canfranc Underground Laboratory

The TREX-DM experiment is conceived to look for low mass WIMPs by means of a gas time projection chamber equipped with novel micromegas readout planes at the Canfranc Underground Laboratory. The detector can hold 20 l of pressurized gas up to 10 bar, which corresponds to 0.30 kg of Ar, or alternatively, 0.16 kg of Ne. The micromegas will be read with a self-triggered acquisition, allowing for effective thresholds below 0.4 keV (electron equivalent). The preliminary background model, following a complete material screening program, points to levels of the order of 1-10 counts keV−1 kg−1 d−1 in the region of interest, making TREX-DM competitive. The status of the commissioning, description of the background model and the corresponding WIMP sensitivity will be presented here.

Development of a 6D Kalman filter for charged particle tracking in time projection chamber without magnetic field

Track reconstruction is necessary for time projection chamber (TPC), because TPCs usually face the measurement error that impedes gaining precise spacial and angular resolution. Kalman filter is a well-performed and applicable algorithm to denoise and reconstruct the event track. In this paper, we develop a six-dimensional Kalman filter to reconstruct the particle track in high-energy physics experiments, while the most common form of Kalman filter used in many research fields is four-dimensional. The modelisation is based on a gaseous TPC, and the whole reconstruction process is first tested by a toy Monte Carlo simulation. The results show the Kalman filter can effectively reduce the noise and improve the detector resolution. Then, the performance of the Kalman filter is also verified with the data produced by the Geant4 toolkit.

AXEL: High-pressure Xe gas TPC for BG-free [formula omitted] decay search

AXEL is a high-pressure xenon gas time projection chamber for neutrinoless double-beta decay (0ν2β) search. The AXEL has a unique readout system called ELCC which has a cellular structure and photosensors to detect electroluminescence light produced by ionization electrons. We demonstrated the performance of the ELCC with a small prototype detector (AXEL-HP10L). The obtained energy resolution corresponds to 0.82−1.74% (FWHM) at the 0ν2β Q-value. We are constructing a new prototype (AXEL-HP180L) in order to study the energy resolution at the Q-value of 0ν2β with a new design of ELCC with unit structure, newly developed electronics board, field-shaping electrodes, and Cockcroft–Walton-type high voltage power supply. For a future 1-ton scale large AXEL detector, we are developing new background-reduction techniques; topology identification with machine learning, positive-ion detection, and active-shield options.

Background assessment for the TREX dark matter experiment

TREX-DM is conceived to look for low-mass Weakly Interacting Massive Particles (WIMPs) using a gas Time Projection Chamber equipped with Micromegas readout planes at the Canfranc Underground Laboratory. The detector can hold in the active volume sim 20~l of pressurized gas up to 10 bar, corresponding to 0.30 kg of Ar or 0.16 kg of Ne. The Micromegas are read with a self-triggered acquisition, being thresholds below 0.4 keV (electron equivalent) at reach. A low background level in the lowest energy region is another essential requirement. To assess the expected background, all the relevant sources have been considered, including the measured fluxes of gamma radiation, muons and neutrons at the Canfranc Laboratory, together with the activity of most of the components used in the detector and ancillary systems, obtained in a complete assay program. The background contributions have been simulated by means of a dedicated application based on Geant4 and a custom-made code for the detector response. The background model developed for the detector presently installed in Canfranc points to levels from 1 to 10 counts hbox {keV}^{-1} hbox {kg}^{-1} hbox {day}^{-1} in the region of interest, making TREX-DM competitive in the search for low-mass WIMPs. A roadmap to further decrease it down to 0.1 counts hbox {keV}^{-1} hbox {kg}^{-1} hbox {day}^{-1} is underway.

PandaX-III high pressure xenon TPC for Neutrinoless Double Beta Decay search

The PandaX-III experiment uses high pressure Time Projection Chambers (TPCs) to search for Neutrinoless Double Beta Decay (NLDBD) of 136Xe, with high energy resolution and sensitivity at the China Jin-Ping underground Laboratory II (CJPL-II). Fine-pitch Microbulk Micromegas will be used for charge amplification and readout in order to reconstruct both the energy and track of the NLDBD event. In the first phase of the experiment, the detector, which contains 200 kg of 90% 136Xe enriched gas operated at 10 bar, will be immersed in a large water tank to ensure 5 m of water shielding. For the final phase, a ton-scale experiment with multiple TPCs will be constructed to improve the detection probability and sensitivity. A 20-kg scale prototype TPC with 7 Micromegas modules has been built to optimize the design of Micromegas readout modules, and to study the energy calibration of the gaseous TPC . The preliminary results of the PandaX-III prototype TPC will be also presented in this paper.

Status of the NEXT project

The NEXT program is developing the technology of high-pressure Xe gas Time Projection Chambers with electroluminescent amplification (HPXe-EL) for neutrinoless double beta decay searches in 136Xe. After completing the first phase of the program with prototypes containing ∼1 kg Xe, the collaboration presently operates the NEXT-White demonstrator. NEXT-White is a 1:2 model NEXT-100, planned for construction in 2020, which will serve as a 100 kg-scale demonstrator of the HPXe-EL technology towards detector masses on the ton-scale. This contribution focuses on the latest results from NEXT-White on energy resolution, topology and background rate, and briefly discusses the future plans of the collaboration.

Simulation of different options of the Inner Tracker for Novosibirsk Super Charm-Tau Factory Detector

Inner Tracker of Novosibirsk Super Charm-Tau Factory Detector has to measure momenta of soft hadrons, which do not reach the drift chamber; complement the drift chamber in measuring the momenta; detect secondary vertices of short-lived particles. Thus, proper choice of the option for the Inner Tracker is of significant interest. The simulation of charged pions propagation in the perpendicular direction to the beam axis was carried out with DD4HEP program based on GEANT4. Three options were considered: 4-layered Silicon microstrip detector, 4-layered cylindrical Gas Electron Multiplier (GEM) detector and Time Projection Chamber (TPC). The simulated Detector was located in 1.5 T magnetic field directed along beam axis. The simulation shows that pions with initial momenta less than 50 MeV/c do not pass through the beampipe and cannot be registered. Pions with momenta above 65 MeV/c leave energy depositions in all 4 layers of the Inner Tracker based on Silicon, and their trajectories can be reconstructed. Cylindrical GEM detector provides reconstruction possibility (hits in 4 layers) for pions with momenta more than 60 MeV/c. TPC with thin inner wall provides reconstruction of pions with momenta higher than 55 MeV/c. However, in this case the reconstruction procedure will be much more complicated due to a large number of background particle tracks in the sensitive volume.

Calibration of the NEXT-White detector using 83mKr decays

The NEXT-White (NEW) detector is currently the largest radio-pure high-pressure xenon gas time projection chamber with electroluminescent readout in the world. It has been operating at Laboratorio Subterr'aneo de Canfranc (LSC) since October 2016. This paper describes the calibrations performed using 83mKr decays during a long run taken from March to November 2017 (Run II). Krypton calibrations are used to correct for the finite drift-electron lifetime as well as for the dependence of the measured energy on the event transverse position which is caused by variations in solid angle coverage both for direct and reflected light and edge effects. After producing calibration maps to correct for both effects we measure an excellent energy resolution for 41.5 keV point-like deposits of (4.553 ± 0.010 (stat) ± 0.324 (sys))% FWHM in the full chamber and (3.804 ± 0.013 (stat) ± 0.112 (sys))% FWHM in a restricted fiducial volume. Using naive 1/√E scaling, these values translate into resolutions of (0.5916 ± 0.0014 (stat) ± 0.0421 (sys))% FWHM and (0.4943 ± 0.0017 (stat) ± 0.0146 (sys))% FWHM at the Qββ energy of xenon double beta decay (2458 keV), well within range of our target value of 1%.

High voltage insulation and gas absorption of polymers in high pressure argon and xenon gases

High pressure gas time projection chambers (HPGTPCs) are made with a variety of materials, many of which still await proper characterization in high pressure noble gas environments. As HPGTPCs increase in size toward ton-scale detectors, assemblies become larger and more complex, creating a need for detailed understanding of how structural supports and high voltage insulators behave. This includes identification of materials with predictable mechanical properties and without surface charge accumulation that may lead to field deformation or sparking. This paper explores the mechanical and electrical effects of high pressure gas environments on insulating polymers PTFE, HDPE, PEEK, POM and UHMW in argon and xenon, including studying gas absorption, swelling and high voltage insulation strength.

Signal-background discrimination with convolutional neural networks in the PandaX-III experiment using MC simulation

The PandaX-III experiment will search for neutrinoless double beta decay of $^{136}$Xe with high pressure gaseous time projection chambers at the China Jin-Ping underground Laboratory. The tracking feature of gaseous detectors helps suppress the background level, resulting in the improvement of the detection sensitivity. We study a method based on the convolutional neural networks to discriminate double beta decay signals against the background from high energy gammas generated by $^{214}$Bi and $^{208}$Tl decays based on detailed Monte Carlo simulation. Using the 2-dimensional projections of recorded tracks on two planes, the method successfully suppresses the background level by a factor larger than 100 with a high signal efficiency. An improvement of $62\%$ on the efficiency ratio of $\epsilon_{s}/\sqrt{\epsilon_{b}}$ is achieved in comparison with the baseline in the PandaX-III conceptual design report.

Three-dimensional convolutional neural networks for neutrinoless double-beta decay signal/background discrimination in high-pressure gaseous Time Projection Chamber

In the search for neutrinoless double-beta decay, the high-pressure gaseous Time Projection Chamber has a distinct advantage, because the ionization charge tracks produced by particle interactions are extended and the detector captures the full three-dimensional charge distribution with appropriate charge readout systems. Such information of tracks provides a crucial extra-handle for discriminating signal events against backgrounds. In this paper, we constructed a toy model to demonstrate where the discrimination power comes from and how much of it the neural network models have already harnessed. Then we adapted 3-dimensional convolutional and residual neural networks on the simulated double-beta and background charge tracks and tested their capabilities in classifying these two types of events. We show that both the 3D structure and the overall depth of the neural networks significantly improve the accuracy of the classifier and lead to results better than previous works. We also studied their performance under various spatial granularities as well as different diffusion and noise conditions. The results indicate that the methods are stable and generalize well despite varying experimental conditions.

Electron drift properties in high pressure gaseous xenon

Gaseous time projection chambers (TPC) are a very attractive detector technology for particle tracking. Characterization of both drift velocity and diffusion is of great importance to correctly assess their tracking capabilities. NEXT-White is a High Pressure Xenon gas TPC with electroluminescent amplification, a 1:2 scale model of the future NEXT-100 detector, which will be dedicated to neutrinoless double beta decay searches. NEXT-White has been operating at Canfranc Underground Laboratory (LSC) since December 2016. The drift parameters have been measured using 83mKr for a range of reduced drift fields at two different pressure regimes, namely 7.2 bar and 9.1 bar. The results have been compared with Magboltz simulations. Agreement at the 5% level or better has been found for drift velocity, longitudinal diffusion and transverse diffusion.