Journal of Advanced Instrumentation in Science

Testing Muography for Subsurface Geophysical Surveys at the Lousal Mine

Thu, 22 Feb 2024 17:55:42 +0000

The LouMu collaboration was established between the Laboratory of Instrumentation and Experimental
Particle Physics (LIP), the Institute of Earth Sciences (ICT), and the Ciencia Viva Center of Lousal, to create ˆ
the conditions for the use of muography as a novel method for subsurface geophysical surveys in Portugal,
starting with an end-to-end test at the Lousal Mine. The exploitation of the Lousal Mine, located in the
Iberian Pyrite Belt, ended in 1988, and it was then rehabilitated as the core of a science center. An 18-
meter-deep gallery was kept accessible, allowing the operation of a muon telescope. Detailed surveys of
the gallery and surroundings were done to help establish the muography targets and interpret the first
results. In April 2022, the muon telescope was installed at Lousal and soon obtained the image of the
first geological target: the Corona geological fault crossing the gallery. The analysis proceeds with the
development of the methods for translating these into local density maps and for combined inversion of
muography with other datasets. The aim is not only to provide the best knowledge on Lousal, but also to
prepare for other geophysical surveys.

Plans for Muography of Samail Ophiolite

Thu, 22 Feb 2024 17:57:41 +0000

Oceanic lithosphere cycling produces critical resources for the economy and governs the occurrence of various natural hazards from earthquakes to volcanic eruptions. Only a small portion of the shallow oceanic lithosphere is explored. The physical nature and geological meaning of the upper and lower crust boundaries and Mohoroviˇci´c discontinuity (Moho) between the oceanic crust and mantle are poorly understood. Direct observations of oceanic crust were conducted in two oceanic drilling holes; however, the Moho has not yet been reached. Former Moho transition zones are exposed on land in numerous ophiolites around the world; thus, the ophiolites are a very important clue to understand the correlation between ocean crust-mantle structure and geology. The Samail Ophiolite is the most promising analogue for oceanic lithosphere. We plan to conduct muography of the Samail Ophiolite to understand the density stratification of the oceanic crust to the mantle, which regulates the geological structure of the oceanic crust to mantle. We discuss the scientific background, the simulation studies, and the design of the muographic surveys.

Muon tomography of the Physics Department of the University of Coimbra

Thu, 22 Feb 2024 18:37:16 +0000

The LouMu is the first project of muography in Portugal, more particularly of transmission muography. It
has employed an RPC muon telescope to perform the imaging of a building, the Physics Department of the
University of Coimbra, and of a geological structure, the Lousal mine. Regarding the muon tomography of
the former, data analysis was already carried out to obtain 2D transmission maps that compare well with
simulation and efforts are being made to use these maps to reconstruct 3D images of the University build-
ing. In this work, three image reconstruction methods are applied: back-projection, analytical inversion,
and iterative reconstruction. While the first two were not successful given the muon telescope’s spatial res-
olution and given the type of structures encompassed when imaging a building, the iterative method has
led to promising results in simulation and is, now, being applied to real data acquired at the University.

Mapping Water on the Moon and Mars Using a Muon Tomography

Olin Lyod Pinto (Author) — Fri, 01 Mar 2024 13:45:56 +0000

The search for water on the Lunar and Martian surfaces is a fundamental aspect of space exploration, con-
tributing to the understanding of the history and evolution of these celestial bodies. However, the current
understanding of the distribution, concentration, origin, and migration of water on these surfaces is lim-
ited. Moreover, there is a need for more detailed data on these aspects of Lunar and Martian water. The
natural flux of cosmic-ray muons, capable of penetrating the planetary surface, offers a method to study
the water-ice content, composition, and density of these surfaces. In this paper, the author presents a novel
approach to address these knowledge gaps by employing cosmic-ray muon detectors and backscattered
radiation. The study describes a cutting-edge muon tracking system developed by GScan and highlights
the results of preliminary simulations conducted using GEANT4. These findings suggest that muon to-
mography could be a potential tool for investigating water-ice content on the Lunar and Martian surfaces,
pointing to new avenues for space science exploration.

Muographic Study of the Palazzone Necropolis (Perugia-Italy)

Thu, 07 Mar 2024 19:27:23 +0000

The Palazzone Necropolis, located southeast of the hill of Perugia (Italy), is an Etruscan archaeological site
open to the public, and well-known thanks to the numerous finds and its (∼)200 tombs from the Hellenistic
age and 5 from the Archaic period. The most important tomb is represented by the Volumni Hypogeum.
The Palazzone Necropolis is also defined as an archaeogeosite as it has been the subject of geological stud-
ies which, through the observation of the walls of the tombs, has made it possible to expand the geological
framework for the interpretation of the formation of the Perugia hill. However, in the Palazzone Necrop-
olis, the presence of other tombs is not excluded, especially in the eastern area of the archaeological site
which is currently not open to visitors. The muography technique, thanks to the great penetrating power of
atmospheric muons, fits into this context for the noninvasive identification of undiscovered cavities. This
contribution will present the preliminary results of the muographic campaign carried out at the Palazzone
Necropolis in which the observation of an entire hill was carried out. The results are also inserted in a
geological context for the verification of the densities of the sediments that are present in this territory.

Stand-Alone Cosmic-Ray Tomography with Secondary Particles

Maximilian Pérez Prada, Sarah Barnes, Maurice Stephan (Author) — Thu, 07 Mar 2024 19:34:21 +0000

The imaging technique of cosmic-ray tomography is usually based on the measurement of muon transmis-
sion and muon scattering within the examined volume. Secondary particles produced from the interaction

of air shower particles with the target material have been proven to carry complementary information
directly related to the target material properties. However, this additional information has not been fully
exploited so far. Previous work by the authors [Analysis of Secondary Particles as a Complement to Muon
Scattering Measurements. Instruments 2022, 6] showed a novel approach utilizing only the information
from secondary particles to successfully reconstruct and discriminate a variety of materials in the context
of shipping container scanning with an optimal detector setup and background-free environment. This

work builds on the previous results and methods, taking more realistic detector parameters into consid-
eration and investigating their impact on material reconstruction and discrimination. A possible detector

setup is discussed, allowing the reconstruction of muons and secondary particle tracks. Three key detector
parameters are varied with the aim of validating the approach of the previous work in a more realistic
scenario. These parameters are the detection efficiency, the spatial resolution, and the spacing between the
detector layers.

A Simulation of a Cosmic Ray Tomography Scanner for Trucks and Shipping Containers

Thu, 07 Mar 2024 19:37:28 +0000

The SilentBorder project aims to develop and construct a new high-technology scanner for the identifica-
tion of hazardous and illegal goods hidden in trucks and sea containers. The scanner will enable scanning
of shipping containers or cargo and is based on muon tomography, a technology that uses natural cosmic
ray muons and therefore is inherently safe for people. We report on the development of a simulation and
reconstruction framework aimed at optimizing the geometry of the detector and exploring feasibility of
CRT in real smuggling scenarios using simulated data. The framework includes GEANT4 modeling of
light transport in a scintillating fiber tracker to optimize the geometry and materials used to produce fiber
mats. A systematic comparison was made of particle generators such as CRY, MUSIBO, and EcoMug in-
terfaced with the GEANT4 toolkit to find the most effective one for modeling real smuggling scenarios.
The Point-of-Closest-Approach reconstruction algorithm was used to create 3D images of sea containers
or trucks. An analysis of the sensitivity of CRT was performed using simulated synthetic data generated
for different smuggling scenarios of contraband of low-Z organic materials and high-Z inorganic mate-
rials. Results of our research indicate that by using muon tomography, it would be possible to improve
the performance and sensitivity of sea container and cargo screening systems to overcome limitations of
traditional screening methods, such as X-ray scanners, when it comes to detecting illicit materials that may
be well concealed. CRT can provide a complementary imaging technique that could enhance the detection
capabilities of existing systems.

Latest Developments in Tomographic Research of Underground and Large Structures with Muographic Expertise, TRUST-ME

Clément Risso, Ignacio Lázaro Roche (Author) — Thu, 07 Mar 2024 19:52:14 +0000

The TRUST-ME project aims at validating a new application of MUon Survey Tomography based on Mi-
cromegas detector for Unreachable Sites Technology (MUST2) to address a societal challenge of increasing
importance: sustainable water management. This muon tracker, conceived and developed by the Labora-
toire souterrain `a bas bruit (LSBB), relies on a Micromegas readout plane with a thin time projection chamber
(TPC). A network of new generation muon trackers is being deployed to both survey groundwater in
aquifers near the LSBB and enhance the safety and operational efficiency of large structures, such as dams.
The resulting compact, high field-of-view detector is able to operate in harsh environments with challeng-
ing access and operational conditions. MUST2 is currently being deployed on a double dam system to
both characterize the detector and monitor the building and its surroundings. In parallel, the combined
use of photogrammetry and LIDAR is tested coupled with muography for the modeling of mid-sized tar-
gets. This publication details the upgrade of the MUST2 technology, with its new and improved features.
It presents the experimental configuration of the detector in a dam monitoring context, and an example of
LIDAR and photogrammetry support for muographic analyses.

Muon Tomography for Reverification of Spent Fuel Casks (the MUTOMCA Project)

Thu, 07 Mar 2024 19:53:28 +0000

The MUTOMCA (MUon TOMography for shielding CAsks) project investigates the suitability of muon
tomography for the reverification of spent fuel casks. Spent fuel casks are stored, for decades, in dedicated
locations and are under constant surveillance by international agencies through unattended monitoring
equipment. In the hypothetical case that these instruments would temporarily fail, thus leading to a loss
of Continuity of Knowledge (CoK), a reverification of the spent fuel enclosed in self-shielding casks would
be required. The reverification is particularly challenging for conventional nondestructive assay (NDA)
methods since thick-walled spent fuel casks considerably attenuate the radiation emitted by the spent fuel.
On the other hand, inspectorates need a high degree of assurance on the amounts of nuclear material
stored in those casks. With the aim of proving the ability of muon tomography to detect a diversion of fuel
assemblies in closed spent fuel casks, an experimental apparatus was designed, developed, constructed,
and commissioned. The detectors were used during the first months of 2023, in a field trial at a dry storage
facility in Germany to examine CASTOR®V/19 casks. Preliminary results are presented along with the
potentials and drawbacks of the experimental apparatus.

Muon Imaging for Cu-Fe Ore Shoot Identification: Results and Next Challenges

Wed, 20 Mar 2024 14:07:07 +0000

Transmission-based muography (TM) is becoming an innovative and nondestructive imaging technique
based on the measurement of the cosmic ray muon flux attenuation within matter, allowing the reconstruction
of two- or three-dimensional transmission and density polar maps. This paper presents our most
recent findings on TM measurements applied to ore shoot prospecting. All measurements and results were
obtained during the MIMA-SITES project years of research. The case study was the Temperino mine in the
San Silvestro Archaeological and Mining Park (Campiglia Marittima, Italy). Here, several magmatic and
metasomatic geological units outcrop. Among them is a Cu-Fe-Zn-Pb(-Ag) sulfide skarn complex primarily
composed of hedenbergite and ilvaite minerals.

Simulation Tools, First Results, and Experimental Status of the MURAVES Experiment

Wed, 20 Mar 2024 14:12:18 +0000

The MUon RAdiography of VESuvius (MURAVES) project aims at the study of Mt. Vesuvius, an active
and hazardous volcano near Naples, Italy, with the use of muons freely and abundantly produced by cosmic
rays. In particular, the MURAVES experiment intends to perform muographic imaging of the internal
structure of the summit of Mt. Vesuvius. The challenging measurement of the rock density distribution in
its summit by muography, in conjunction with data from other geophysical techniques, can help model
possible eruption dynamics. The MURAVES apparatus consists of an array of three independent and identical
muon trackers, with a total sensitive area of 3 square meters. In each tracker, a sequence of 4 XY
tracking planes made of plastic scintillators is complemented by a 60 cm thick lead wall inserted between
the two downstream planes to improve rejection of background from low-energy muons. The apparatus
is currently acquiring data. This paper presents preliminary results from the analysis of the first data samples
acquired with trackers pointing toward Mt. Vesuvius, including the first relative measurement of the
density projection of two flanks of the volcano at three different altitudes; we also present the workflow of
the simulation chain of the MURAVES experiment and its ongoing developments.

TomOpt: Muon Tomography experiment optimization

Tue, 02 Apr 2024 11:10:13 +0000

The Tomopt software is a tool to optimize the geometrical layout and specifications of detectors designed for muon scattering tomography. Based on differentiable programming techniques, Tomopt consists in a modular pipeline that models all the aspects of a muon tomography task, from the generation and interaction of cosmic ray muons with a parameterized detector and passive material, to the inference on the volume properties. This enables the optimization of the detector parameters via gradient descent, to suggest optimal detector configurations and specifications. This optimisation is subjected to various external constraints such as cost, logistic and material identification efficiency.

Experimental Momentum-binning for Muon Scattering Tomography

Botond Csaba Csatlós, Gergő Hamar, Dezső Varga (Author) — Fri, 19 Apr 2024 10:52:25 +0000

Muon scattering tomography is a novel cosmic muon imaging technique that exploits the multiple Coulomb-scattering of the cosmic muons. Imaging and identification of enclosed high-Z materials become possible, and usable in large volume scanners. The proof of concept is supported via several simulation frameworks and experimental demonstrations.

As the scattering angle strongly depends on the momentum of the muon, using that information can enhance the imaging, and allow one to expand the identification capabilities towards lower-Z materials.

We have constructed a muon-scattering experiment using good spatial resolution 80cm-size MWPCs, as a multiple-layer setup for precise tracking. The basics of operation have been proved as mapping the scattering strength in 2D/3D maps of targets with various sizes (from 1cm up) and materials (ranging from plastic to lead). The setup is equipped with additional scattering layers below the post-target tracking part; scattering on these known layers could indicate the momentum of the incoming muon. This novel method opens for momentum tagging and thus momentum-binned imaging, increasing the discrimination power between materials even in lower-Z region.

Use of Generative Adversarial Neural Networks in Scattering Muography

Tue, 30 Apr 2024 09:56:43 +0000

Many muography applications make extensive use of simulations to determine detector design or to train
imaging or regression algorithms. The computing cost of producing these simulations is usually quite high,
especially concerning the interaction of cosmic muons with matter. This work explores the possibility of
using Generative Adversarial Neural (GAN) networks to produce a fast and realistic simulation of the
multiple scattering process. The results of the network are confronted with GEANT4 simulations using a
benchmark problem related to the measurement of the inner wear of industrial pipes. The GAN is able to
reproduce the angular distributions and correlations with a speed-up factor of roughly 50 with respect to
GEANT4.

Investigation of the Impact of Magnetic Fields on Scattering Muography Images

Hamid Basiri, Tadahiro Kin, Eduardo Cortina Gil, Andrea Giammanco (Author) — Tue, 07 May 2024 09:14:41 +0000

Muography is a noninvasive imaging technique that exploits cosmic-ray muons to probe various targets by
analyzing the absorption or scattering of muons. The method is particularly useful for applications ranging
from geophysical exploration to security screening, including the identification of nuclear materials. This
study leverages both Monte Carlo simulations and the Point of Closest Approach (PoCA) algorithm for
image reconstruction to specifically explore the distortions caused by magnetic fields in scattering muography
images. In the PoCA algorithm, it is assumed that all scattering of a muon during its travel in material
occurs at a single point, known as the PoCA point. Each PoCA point is characterized by a scattering
angle, whose distribution provides insights into the density and elemental composition of the target material.
However, magnetic fields can influence muon trajectories according to Lorentz’s law, affecting the
estimated positions of the PoCA points and the calculated scattering angles. This introduces challenges in
applications such as border security control systems. Moreover, the presence of magnetic fields can lead
to what we term “magnetic jamming”, where the resulting muography image is distorted or misleading.
This effect further complicates the accurate identification and interpretation of target materials. Our findings
underline the necessity to account for magnetic field distortions when utilizing scattering muography
in practical scenarios.

B2G4: A synthetic Data Pipeline for the Integration of Blender Models in Geant4 Simulation Toolkit

Wed, 08 May 2024 19:50:03 +0000

The correctness and precision of particle physics simulation software, such as Geant4, are expected to yield
results that closely align with real-world observations or well-established theoretical predictions. Notably,
the accuracy of these simulated outcomes is contingent upon the software’s capacity to encapsulate detailed
attributes, including its prowess in generating or incorporating complex geometrical constructs. While the imperatives of precision and accuracy are essential in these simulations, the need to manually code highly detailed geometries emerges as a salient bottleneck in developing software-driven physics simulations. This research proposes Blender-to-Geant4 (B2G4), a modular data workflow that utilizes Blender to create 3D scenes, which can be exported as geometry input for Geant4. B2G4 offers a range of tools to streamline the creation of simulation scenes with multiple complex geometries and realistic material properties. Here, we demonstrate the use of B2G4 in a muon scattering tomography application to image the interior of a sealed steel structure. The modularity of B2G4 paves the way for the designed scenes and tools to be embedded not only in Geant4, but in other scientific applications or simulation software.

Imaging via Cosmic Muon Induced Secondaries

Gergő Hamar (Author) — Fri, 10 May 2024 11:26:13 +0000

As cosmic muons traverse a target, they interact with it, producing secondary radiation, whose spectrum
depends on the material-composition of the target. This imaging technique is sensitive to low-Z materials
as well, opening a novel noninvasive material-identification method for medium-sized obscure targets.
Our Hungarian-Serbian collaboration pioneered in demonstrating experimentally this unique method, using
gaseous trackers for the muons and a scintillator array and germanium detector for the secondaries.
Results have proven imaging possibilities ranging from metals to soft-tissue targets. Corresponding Geant4
simulations have revealed forward-sideward asymmetry and sensitivity to the electron/gamma ratio. The
former is materialized in a new experimental setup, with large coverage via segmented scintillator arrays,
and a combined and compact DAQ, with an electron-tagging possibility. The paper describes the recent
results in imaging via secondaries and details the new enhanced experimental setup and its first results.

Background Suppression with Machine Learning in Volcano Muography

Gabor Galgoczi, Gabor Albrecht, Gergo Hamar, Dezso Varga (Author) — Tue, 14 May 2024 14:15:49 +0000

In this work, a machine learning algorithm, specifically a deep neural network, is introduced to mitigate
background interference in muography applications, predominantly aimed at volcano imaging. The discussed
detector system is engineered to filter out the low-energy background by incorporating up to five
lead absorber layers interspersed among eight detectors. This detector system underwent a Monte-Carlo
(Geant4) simulation to create training samples for the machine learning algorithm. It demonstrated that the
devised deep neural network outperforms the traditional tracking algorithm in suppressing low-energy
background, thereby rendering significant enhancement via machine learning supplementation.

Underground Muography at Buda Castle

Thu, 06 Jun 2024 12:14:43 +0000

The Buda Castle project is the largest underground muography project of the Wigner Research Centre
for Physics (RCP) and one of the major ones worldwide. The project has been running for more than
four years, and we have about two more years until completion. The research area is the southern part
of the hill of Buda Castle, Budapest, where the present castle and the partly buried ruins of the ancient
buildings are located. The goal is to find every unknown underground void (caves and tunnels) with a
characteristic extent larger than 2 × 2 × 2 m3, as well as to find the zones with significantly lower density
than the surrounding base rock (backfilled cellars, tunnels, rock debris zones, etc.). During the project we
investigate the whole area which can be reached from the presently known underground facilities. Most
of these facilities are at an ideal depth, about 50 m below the surface, and the corridor system available for
measurements is dense enough to populate an appropriate measurement grid to make even 3D inversion
for the uppermost 30 m of almost the entire castle area. Thanks to the wide range of detectors developed
and built by the Wigner RCP, we can measure with good resolution and efficiency even from places that
are difficult to reach. This paper will introduce the project and the first results obtained by 3D triangulation
based on several dozens of already completed measurement points.

Muon Tomography of Underground Fracture Zones

Sat, 22 Jun 2024 08:54:19 +0000

A high resolution muography survey has been performed in the Kiralylaki tunnel in Budapest (Hun- ´
gary) to search for unknown cavities. Preliminary radiographic measurements suggested large density
anomalies above the tunnels in a 20–60 m thick cherty dolomite rock (2.5–2.7 g/cm3). A Bayesian inversion
method has been adapted to overcome the underdetermination originating from the limited-angle tomographic nature of muography. The angular resolution of the gaseous muon detectors enabled a spatial voxel resolution of 1-2 meters, and the 3D distribution of karstic fracture zones has been obtained. Multiple 5–
10 m long core drills validated the existence of low-density regions. The core samples showed convincing
agreement with the inversion, containing fractured rock (altered dolomite powder, below 1.8 g/cm3). This
work confirms the potential of mapping underground fracture zones using muography, which has potential applications in tunnel construction and maintenance, as well as for landslide studies, depending upon
feasible boundary conditions.

Small-Area Portable Resistive Plate Chambers for Muography

Mon, 24 Jun 2024 11:06:50 +0000

Muography is finding applications in various domains such as volcanology, archaeology, civil engineering,
industry, mining, and nuclear waste surveys. To simplify transportation and installation in remote
locations after laboratory testing, a fully portable and autonomous muon telescope based on Resistive
Plate Chambers (RPCs) is being developed. Two glass-RPC prototypes have been created, sharing the
same design goals but with different detector parameters, and comparative studies are ongoing. Drawing
from prototype experience, a double-gap RPC with advanced features and improved spatial resolution is
constructed. Resistive electrodes are produced manually, and a new data acquisition board is currently undergoing calibration. The results on prototype performance, readout board comparisons and the technical
progress on the double-gap RPC are presented.

Direct Dark Matter Searches Using Sodium Iodide Targets: Status and Prospects

María Luisa Sarsa (Author) — Thu, 22 Feb 2024 17:58:59 +0000

Thallium-Activated Sodium Iodide (NaI(Tl)) scintillators have been widely used for radiation detection
since the middle of the XXth century, being applied, for instance, in nuclear medicine, environmental
monitoring, nuclear physics, aerial survey, well logging, homeland security, etc. Among other remarkable features, NaI(Tl) offers a very high intrinsic scintillation light yield and ease of growing large-size
crystals. On the other hand, the hygroscopic character of the material complicates the manipulation and
requires a tight housing of the detector system preventing humidity from reaching the crystal. Energy
ranges from a few keV to several MeV are accessible with state-of-the-art technology, using Photomultiplier Tubes (PMTs) for the light readout. These detectors have been successfully applied since the nineties
of the XXth century in the direct search for dark matter in the form of hypothetical WIMPs (Weakly Interacting Massive Particles) pervading the galactic halo. WIMPs could explain the galactic dynamics and
the 26% of the Universe matter-energy content required to explain the cosmic microwave background
radiation anisotropies, and many other cosmological observations, within the standard ΛCDM cosmological model. DAMA/LIBRA experiment, taking data at Gran Sasso National Laboratory (LNGS), in Italy,
and using NaI(Tl) detectors, has observed for more than twenty years an annual modulation in the detection rate. This modulation shares all the features expected for the galactic dark matter signal. However,
no other experiment has observed any hint supporting the interpretation in terms of dark matter particle interactions of the DAMA/LIBRA result, which seems very difficult to reconcile with the plethora of
negative results from different experiments (using different targets and techniques). Only very recently,
three-sigma sensitivity to DAMA/LIBRA result is at hand using the same target material, NaI(Tl). This
allows us to cancel all the signal dependencies on the particle dark matter model and the dark halo model,
enabling a model independent evaluation of that result. In this article, experimental efforts using NaI(Tl)
detectors aiming at testing the DAMA/LIBRA signal will be briefly revised, as well as the results released,
data-taking status, possible systematics affecting this testing, and sensitivity prospects for the near future.
Finally, some R&D efforts toward the development of new experimental approaches using either NaI(Tl) or
undoped NaI crystals will be revised in the context of the solving of the DAMA/LIBRA puzzle on annual
modulation but also moving forward to other possible applications.

Design Challenges for a Future Liquid Xenon Observatory

Abigail Kopec (Author) — Thu, 22 Feb 2024 17:59:59 +0000

An ultimate liquid xenon experiment would be limited in its dark matter science reach by irreducible neu-
trino backgrounds, which are an exciting signal in their own right. To achieve such sensitivity, other back-
grounds that currently plague these detectors must be better mitigated, and extreme care must be taken in
the design and construction phases. A 100-tonne xenon target is compelling to search for weakly interact-
ing massive particle dark matter and has capabilities to study coherent elastic neutrino-nucleus scattering
and search for neutrinoless double-beta decay signatures. Historically, liquid xenon time projection cham-
bers have scaled to larger target masses with great success. This paper gives an overview of challenges
that need to be met for the next generation of detectors to obtain a kilotonne×year exposure. Such tasks
include the procurement and purification of xenon, radiopure, and reliable detector components, sensitive
outer detector vetoes, powerful data handling and analyses, and an ability to operate stably for timescales
of over a decade.

Challenges for the Directional Dark Matter Direct Detection

Kentaro Miuchi (Author) — Wed, 24 Apr 2024 21:16:46 +0000

Directional methods have been considered to provide solid proof for the direct detection of dark matter. Gaseous time-projection-chambers (TPCs) are the most mature devices for directional dark matter searches although there still exist several challenges to overcome. This paper reviews the history, current challenges, and future prospects of the gaseous TPCs for directional dark matter searches.

Directional Dark Matter Search with Super-Resolution Nuclear Emulsion

Tatsuhiro Naka, Giovanni De Lellis (Author) — Wed, 22 May 2024 10:31:54 +0000

Several approaches for the direct search of dark matter, in which the energy deposited by the scattering
dark matter particle is detected, are extensively used to constrain the mass and interaction strength of
these hypothetical particles. Gaining information on the income direction of the interacting particle would
be the only way to overcome the neutrino floor or to study the properties of any found signal. We are
studying the direction-sensitive dark matter search using a super-high resolution nuclear emulsion, NIT
which stands for Nanoimaging Tracker. NIT consists of silver-halide crystals (AgBr(I)) with diameters at
the 10nm scale. The major feature of NIT is the possibility of detecting nanometric tracks as expected for
nuclear recoils induced by dark matter scattering. The NEWSdm project is carrying out measurements
in the Gran Sasso INFN laboratory, LNGS, in Italy. In this review, we introduce the technologies for the
NEWSdm experiment and discuss the challenges for the near-future dark matter search.

Bubble Chambers for Dark Matter Detection

Ken Clark (Author) — Wed, 22 May 2024 10:34:30 +0000

The use of superheated targets to detect dark matter has been expanding in recent years, taking a worldleading
role in exploring the spin-dependent phase space. This trend will continue; however, there are
groups investigating new versions of this technology which will cover entirely new regions.

Axion-Like Particle Detection in Alkali-Noble-Gas Haloscopes

Kai Wei, Xiaofei Huang, Xiaolin Ma, Wei Ji, Jia Liu, Lei Cong, Wei Quan (Author) — Sat, 22 Jun 2024 09:03:19 +0000

Revealing the essence of dark matter (DM) and dark energy is essential for understanding our universe.
Ultralight (rest energy <10 eV) bosonic particles, including pseudoscalar axions and axion-like particles
(ALPs), have emerged among leading candidates to explain the composition of DM and searching for
them has become an important part of precision-measurement science. Ultrahigh-sensitivity alkali-noblegas-based comagnetometers and magnetometers are being used as powerful haloscopes, i.e., devices designed to search for DM present in the galactic halo. A broad variety of such devices include clockcomparison comagnetometers, self-compensating comagnetometers, hybrid-spin-resonance magnetometer, spin-exchange-relaxation-free magnetometers, nuclear magnetic-resonance magnetometers, Floquet
magnetometers, and masers, as well as devices like the cosmic axion spin-precession experiment (CASPEr)
using liquid 129Xe, prepolarized via spin-exchange optical pumping with rubidium atoms. The combination of alkali metal and noble gas allows one to take the best advantage of the complementary properties of
the two spin systems. This review summarizes the operational principles, experimental setups and the successful explorations of new physics using these haloscopes. Additionally, some limiting factors are pointed
out for further improvement.