Nuclear Emulsion Research Articles

Cancelled: Line Segment Detection Based on False Peak Suppression and Local Hough Transform and Application to Nuclear Emulsion

Cancelled: Line Segment Detection Based on False Peak Suppression and Local Hough Transform and Application to Nuclear Emulsion

Hypernuclear event detection in the nuclear emulsion with Monte Carlo simulation and machine learning

This study developed a novel method for detecting hypernuclear events recorded in nuclear emulsion sheets using machine learning techniques. The artificial neural network-based object detection model was trained on surrogate images created through Monte Carlo simulations and image-style transformations using generative adversarial networks. The performance of the proposed model was evaluated using α-decay events obtained from the J-PARC E07 emulsion data. The model achieved approximately twice the detection efficiency of conventional image processing and reduced the time spent on manual visual inspection by approximately 1/17. The established method was successfully applied to the detection of hypernuclear events. This approach is a state-of-the-art tool for discovering rare events recorded in nuclear emulsion sheets without any real data for training.

Studies of three-and four-body hypernuclei with heavy-ion beams, nuclear emulsions and machine learning

Interests on few-body hypernuclei have been increased by recent results of experiments employing relativistic heavy ion beams. Some of the experiments have revealed that the lifetime of the lightest hypernucleus, hypertriton, is significantly shorter than 263 ps which is expected by considering the hypertriton to be a weakly-bound system. The STAR collaboration has also measured the hypertriton binding energy, and the deduced value is contradicting to its formerly known small binding energy. These measurements have indicated that the fundamental physics quantities of the hypertriton such as its lifetime and binding energy have not been understood, therefore, they have to be measured very precisely. Furthermore, an unprecedented Λnn bound state observed by the HypHI collaboration has to be studied in order to draw a conclusion whether or not such a bound state exists. These three-body hypernuclear states are studied by the heavy-ion beam data in the WASA-FRS experiment and by analysing J-PARC E07 nuclear emulsion data with machine learning.

ScanPyramids project: Overview on the Validity and Limitations of Non-destructive Techniques

In 2017, ScanPyramids project (www.scanpyramids.org) published a paper in Nature (Morishima et al., 2017) revealing the discovery of a big void (ScanPyramids Big Void BV) observed with nuclear emulsion films (Muography), it has a cross-section similar to that of the Grand Gallery and a minimum length of 30 meters situated above the Grand Gallery. In addition, a geometrically non-identified void in the Northern Face of the Pyramid (ScanPyramids Northern Face Corridor SP-NFC) was detected as well in 2017 followed by further detailed and focused muography measurements up to 2022 (Morishima and Procureur et al., 2023). ScanPyramids SP-NFC corridor has been investigated in more detail with a wider set of non-destructive techniques. The result of GPR, Ultrasonic and image fusion detected precisely the location and shape of ScanPyramids SP-NFC (Elkarmoty and Rupfle et al.,2023). In this paper, we present overview on the application of Muography, Ground Penetrating Radar, Ultrasonic Tomography, and Electrical Resistivity Tomography on the Chevron of the Great Pyramid where ScanPyramids SPNFC is located behind. The objective of the NDT measurements is to detect the geometry, location, orientation, and extension of ScanPyramids SP-NFC with more than one NDT method. The paper addresses the validity and limitations of each method used providing the limitations of each technique in this particular case study.

Directional sensitivity of the NEWSdm experiment to cosmic ray boosted dark matter

We present a study of a directional search for Dark Matter boosted forward when scattered by cosmic-ray nuclei, using a module of the NEWSdm experiment. The boosted Dark Matter flux at the edge of the Earth's atmosphere is expected to be pointing to the Galactic Center, with a flux 15 to 20 times larger than in the transverse direction.The module of the NEWSdm experiment consists of a 10 kg stack of Nano Imaging Trackers, i.e. newly developed nuclear emulsions with AgBr crystal sizes down to a few tens of nanometers. The module is installed on an equatorial telescope.The relatively long recoil tracks induced by boosted Dark Matter, combined with the nanometric granularity of the emulsion, result in an extremely low background.This makes an installation at the INFN Gran Sasso laboratory, both on the surface and underground, viable. A comparison between the two locations is made.The angular distribution of nuclear recoils induced by boosted Dark Matter in the emulsion films at the surface laboratory is expected to show an excess with a factor of 3.5 in the direction of the Galactic Center. This excess allows for a Dark Matter search with directional sensitivity.The surface laboratory configuration prevents the deterioration of the signal in the rock overburden and it emerges as the most powerful approach for a directional observation of boosted Dark Matter with high sensitivity.We show that, with this approach, a 10 kg module of the NEWSdm experiment exposed for one year at the Gran Sasso surface laboratory can probe Dark Matter masses between 1 keV/c2 and 1 GeV/c2 and cross-section values down to 10-30 cm2 with a directional sensitive search.

SND@LHC: A New Experiment in Neutrino Physics at the LHC

The SND@LHC detector experiment is located at the Large Hadron Collider (LHC), about 480 m downstream of the ATLAS interaction point. The detector is designed to measure, for the first time ever, high-energy neutrinos produced at the LHC in the pseudorapidity region of 7.2<η<8.4, which is inaccessible to other LHC experiments. The detector comprises a hybrid system that incorporates multiple components. The detector includes a 830 kg target composed of tungsten plates arranged in alternating layers with nuclear emulsion and electronic trackers: this arrangement functions as an electromagnetic calorimeter. Following the electromagnetic calorimeter, there is a hadronic calorimeter and a muon identification system. The detector possesses the ability to differentiate interactions involving all three neutrino flavours, enabling investigations into the physics of heavy flavour production in the forward region. This research is particularly significant for future circular colliders and high-energy astrophysical neutrino experiments. Furthermore, the detector has the ability to search for the scattering of Feebly Interacting Particles. The detector started operating during the LHC Run 3, and it collected a total of ∼39 fb−1 in 2022. The detector aims to collect approximately 250 fb−1 in the whole of Run 3.

Study of multiplicity fluctuations in terms of strongly intensive quantity in forward-backward zone

A completely new study of forward-backward multiplicity fluctuation of produced pions in nuclear emulsion detector has been carried out by the method of strongly intensive quantity ΣFB for 16O-AgBr, 28Si-AgBr and 32S-AgBr interactions at 4.5 AGeV/c. Experimental analysis has been compared using MC-RAND events and UrQMD simulated events. UrQMD model could not reproduce the experimental results. Outcome of this analysis supports the presence of dynamical fluctuations in multiparticle production at 4.5 AGeV/c. The results on strongly intensive fluctuation measures at a lower energy show much larger fluctuations in comparison to the higher energy data studied so far.

Age, dose, and binding to TfR on blood cells influence brain delivery of a TfR-transported antibody

BackgroundTransferrin receptor 1 (TfR1) mediated brain delivery of antibodies could become important for increasing the efficacy of emerging immunotherapies in Alzheimer's disease (AD). However, age, dose, binding to TfR1 on blood cells, and pathology could influence the TfR1-mediated transcytosis of TfR1-binders across the blood–brain barrier (BBB). The aim of the study was, therefore, to investigate the impact of these factors on the brain delivery of a bispecific TfR1-transported Aβ-antibody, mAb3D6-scFv8D3, in comparison with the conventional antibody mAb3D6.MethodsYoung (3–5 months) and aged (17–20 months) WT and tg-ArcSwe mice (AD model) were injected with 125I-labeled mAb3D6-scFv8D3 or mAb3D6. Three different doses were used in the study, 0.05 mg/kg (low dose), 1 mg/kg (high dose), and 10 mg/kg (therapeutic dose), with equimolar doses for mAb3D6. The dose-corrected antibody concentrations in whole blood, blood cells, plasma, spleen, and brain were evaluated at 2 h post-administration. Furthermore, isolated brains were studied by autoradiography, nuclear track emulsion, and capillary depletion to investigate the intrabrain distribution of the antibodies, while binding to blood cells was studied in vitro using blood isolated from young and aged mice.ResultsThe aged WT and tg-ArcSwe mice showed significantly lower brain concentrations of TfR-binding [125I]mAb3D6-scFv8D3 and higher concentrations in the blood cell fraction compared to young mice. For [125I]mAb3D6, no significant differences in blood or brain delivery were observed between young and aged mice or between genotypes. A low dose of [125I]mAb3D6-scFv8D3 was associated with increased relative parenchymal delivery, as well as increased blood cell distribution. Brain concentrations and relative parenchymal distribution of [125I]mAb3D6-scFv8D6 did not differ between tg-ArcSwe and WT mice at this early time point but were considerably increased compared to those observed for [125I]mAb3D6.ConclusionAge-dependent differences in blood and brain concentrations were observed for the bispecific antibody mAb3D6-scFv8D3 but not for the conventional Aβ antibody mAb3D6, indicating an age-related effect on TfR1-mediated brain delivery. The lowest dose of [125I]mAb3D6-scFv8D3 was associated with higher relative BBB penetration but, at the same time, a higher distribution to blood cells. Overall, Aβ-pathology did not influence the early brain distribution of the bispecific antibody. In summary, age and bispecific antibody dose were important factors determining brain delivery, while genotype was not.

Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons

Khufu’s Pyramid is one of the largest archaeological monument all over the world, which still holds many mysteries. In 2016 and 2017, the ScanPyramids team reported on several discoveries of previously unknown voids by cosmic-ray muon radiography that is a non-destructive technique ideal for the investigation of large-scale structures. Among these discoveries, a corridor-shaped structure has been observed behind the so-called Chevron zone on the North face, with a length of at least 5 meters. A dedicated study of this structure was thus necessary to better understand its function in relation with the enigmatic architectural role of this Chevron. Here we report on new measurements of excellent sensitivity obtained with nuclear emulsion films from Nagoya University and gaseous detectors from CEA, revealing a structure of about 9 m length with a transverse section of about 2.0 m by 2.0 m.

Development of High-Resolution Nuclear Emulsion Plates for Synchrotron X-Ray Topography Observation of Large-Size Semiconductor Wafers

Characterization of defects in semiconductor wafers is essential for the development and improvement of semiconductor devices, especially power devices. X-ray topography (XRT) using synchrotron radiation is a powerful methods used for defect characterization. To achieve detailed characterization of large-size semiconductor wafers by synchrotron XRT, we have developed nuclear emulsion plates reaching a high-resolution and wide dynamic range. We have shown that higher-resolution XRT images could be obtained using emulsions with smaller iodobromide crystals, and demonstrated clear observation of threading edge dislocations in a SiC epitaxial layer having small contrast. Furthermore, we demonstrated XRT image acquisition for almost all of a 150-mm SiC wafer with one plate. Our development will contribute to advances in electronic materials, especially in the field of power electronics, in which defect characterization is important for improving the performance and yield of devices.

Investigation of neutron imaging applications using fine-grained nuclear emulsion

Neutron imaging is a nondestructive inspection technique that has a wide range of applications. One of the important aspects of neutron imaging is achieving a micrometer-scale spatial resolution. The development of a high-resolution neutron detector is a challenging task. As one potential solution to this task, we investigate whether neutron detectors based on fine-grained nuclear emulsions are suitable for high-resolution neutron imaging applications. High track density is necessary to improve the quality of neutron imaging. However, the available track analysis methods are difficult to apply under high track density conditions. Simulated images are used to determine the required track density for neutron imaging. A track density of the order of 104 tracks per 100×100μm2 is sufficient to utilize neutron detectors for imaging applications. Contrast resolution was also investigated for image datasets with various track densities and neutron transmission rates. Moreover, experiments were performed for the neutron imaging of gadolinium-based gratings with known geometries. The grating structures were successfully resolved. The calculated 1σ 10%–90% edge response using the grayscale optical images of the grating slit with a periodic structure of 9 μm was 0.945±0.004 μm.

Studies of angular distribution of the grey particles in 16O-emulsion collision at 3.7A GeV

By means of [Formula: see text] emulsion track detectors, we report the characteristics of the experimental angular distributions of the fast target protons (grey particles) emitted in interactions of [Formula: see text]O with emulsion nuclei at 3.7A[Formula: see text]GeV. Grey tracks in nuclear emulsion corresponding protons with kinetic energy in the ranges [Formula: see text][Formula: see text]MeV. The angular distributions are compared with those resulting from interactions of other projectiles ([Formula: see text]C, [Formula: see text]Ne and [Formula: see text]Si) at nearly the same incident energy. These angular distributions are studied at different target sizes ([Formula: see text]-values) and at various projectile spectator charges ([Formula: see text]-values) in the framework of the modified Maxwell– Boltzmann statistical model. The nuclear limiting fragmentation hypothesis is shown to be fulfilled for these target protons angular distributions which are found to be independent of the target size and centrality of collisions. Also, the size of the projectile is found to be ineffective at Dubna energies. The angular distributions of all groups of events possess peaks positioned at [Formula: see text]. The calculated statistical moments of the distributions along with skewness and kurtosis are investigated in addition to the forward-backward asymmetry ratio [Formula: see text] for the different groups of events.

Environmental sub-MeV neutron measurement at the Gran Sasso surface laboratory with a super-fine-grained nuclear emulsion detector

The measurement of environmental neutrons is particularly important in the search for new physics, such as dark matter particles, because neutrons constitute an often irreducible background source. The measurement of the neutron energy spectra in the sub-MeV scale is technically difficult because it requires a very good energy resolution and a very high $\ensuremath{\gamma}$-ray rejection power. In this study, we used a super-fine-grained nuclear emulsion, called nano imaging tracker, as a neutron detector. The main target of neutrons is the hydrogen (proton) content of emulsion films. Through a topological analysis, proton recoils induced by neutron scattering can be detected as tracks with submicrometric accuracy. This method shows an extremely high $\ensuremath{\gamma}$-ray rejection power, at the level of $5\ifmmode\times\else\texttimes\fi{}{10}^{7}\phantom{\rule{0.16em}{0ex}}\ensuremath{\gamma}/{\mathrm{cm}}^{2}$, which is equivalent to five years accumulation of environmental $\ensuremath{\gamma}$ rays, and a very good energy and direction resolution even in the sub-MeV energy region. In order to carry out this measurement with sufficient statistics, we upgraded the automated scanning system to achieve a speed of 250 g/(year machine). We calibrated the detector performance of this system with 880 keV monochromatic neutrons: a very good agreement with the expectation was found for all the relevant kinematic variables. The application of the developed method to a sample exposed at the INFN Gran Sasso surface laboratory provided the first measurement of sub-MeV environmental neutrons with a flux of $(7.6\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\phantom{\rule{0.16em}{0ex}}n/({\mathrm{cm}}^{2}\phantom{\rule{0.16em}{0ex}}\mathrm{s})$ in the proton energy range between 0.25 and 1 MeV (corresponds to neutron energy range between 0.25 and 10 MeV), consistent with the prediction. The neutron energy and direction distributions also show a good agreement.

Directional search for dark matter using nuclear emulsions with NEWSdm

Cosmological observations indicate that most of the matter in the Universe is Dark Matter. Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs) can be detected directly, via its elastic scattering off target nuclei. Most current direct detection experiments only measure the energy of the recoiling nuclei. However, directional detection experiments are sensitive to the direction of the nuclear recoil as well. NEWSdm is meant to be the first experiment with a solid target for directional dark matter searches: the use of a nuclear emulsion based detector, acting both as target and tracking device, would allow to extend dark matter searches beyond the neutrino floor and provide an unambiguous signature of the detection of Galactic dark matter.

Measurement method for laser-accelerated multi-hundred-MeV protons utilizing multiple Coulomb scattering in an emulsion cloud chamber

We have developed a measurement method for laser-accelerated multi-hundred-MeV-class protons using an emulsion cloud chamber (ECC), which consists of a stack of nuclear emulsion films and scatterer plates. Based on multiple Coulomb scattering (MCS) theory depending on the incident energy of protons, we have constructed a regression model to inversely estimate the incident energy by means of support vector regression (SVR) with a radial basis function. The prediction accuracy was approximately 10% (standard deviation) for protons with energies up to 0.3 GeV in a 25 layer ECC with 0.5 mm thick tungsten plates, corresponding to a 2 cm thick compact detector.

Ξ − atomic X-ray spectroscopy using a counter-emulsion hybrid method

Abstract Ξ− atomic X-ray spectroscopy is one of the most useful methods for investigation of the Ξ–nucleus strong interaction. Since the X-ray energy is shifted and/or broadened due to the Ξ–nucleus strong interaction compared to those calculated from electromagnetic interaction alone, the measurement of the energy shift, ΔE, and the width, Γ, give us information on the Ξ–nucleus potential. A serious problem in the measurement is the significant background derived from in-flight Ξ− decay. A novel method of identifying stopped Ξ− events using the nuclear emulsion was developed to realize the first Ξ− atomic X-ray spectroscopy experiment as the J-PARC E07 experiment, which also aimed at searching for ΛΛ and Ξ− hypernuclei in the emulsion. The X-rays emitted from Ξ− Br and Ξ− Ag atoms were measured using germanium detectors. No clear peaks were observed in the obtained spectra. However, we succeeded in reducing the background to 1/170 by this method employing coincidence measurements using nuclear emulsion and X-ray detectors.

Momentum reconstruction of charged particles using multiple Coulomb scatterings in a nuclear emulsion detector

Abstract This paper describes a new method for momentum reconstruction of charged particles using multiple Coulomb scatterings in a nuclear emulsion detector with a layered structure of nuclear emulsion films and target materials. The method utilizes the scattering angles of particles precisely measured in the emulsion films. The method is based on the maximum likelihood to include the new information on the decrease of the energy as the particle travels through the detector. According to the Monte Carlo simulations, this method can measure momentum with a resolution of 10% for muons of ${500}\, {\rm MeV}/c$ passing through the detector perpendicularly. The momentum resolution is evaluated to be 10–20%, depending on the momentum and emission angle of the particle. By accounting for the effect of the energy decrease, the momentum can be reconstructed correctly with less bias, particularly in the low-momentum region. We apply this method to measure the momentum of muon tracks detected in the Neutrino Interaction research with Nuclear emulsion and J-PARC Accelerator (NINJA) experiment where the momentum is also measured independently by using the track range. The two measurements agree well within experimental uncertainties, verifying the method experimentally. This method will extend the measurable phase space of muons and hadrons in the NINJA experiment.

Dark matter event in nuclear emulsions: Comparative analysis by time-resolved photoconductivity of silver halide grains

Dark matter (DM) detection by new nuclear emulsions composed of 40 nm AgBrI grains (Lindhard–Scharff theory) has been compared with minimum ionizing particle (MIP) detection and radiation therapy (RT) by conventional nuclear emulsions composed of 200 nm AgBrI grains (Bethe-Bloch theory), and with picture-taking by color films composed of 500–1000 nm AgBrI grains (band-to-band transition), and characterized by its uniqueness: latent image formation in the presence of electron–hole pairs with extremely high concentration (∼1000/grain) and insufficient space for chemical sensitization centers on a grain (∼10/grain). While AgBrI grains in nuclear emulsions for RT are also associated with electron–hole pairs with high concentration, they have space available for chemical sensitizations. Then, we have studied the effect of these characteristics on latent image formation by analyzing the behaviors of electrons and positive holes with variation of their concentrations in 200 nm AgBr grains by means of time-resolved microwave and radio-frequency photoconductivity methods. It has been predicted from the results of the above-stated experiments that DM detection and RT by nuclear emulsions are disturbed by direct recombination and by reaction between Agn and Br2 owing to high activity of positive holes on the contrary to MIP detection by nuclear emulsions and picture-taking by color films, both of which are solely disturbed by indirect recombination. On the basis of the obtained results, discussions are made on ideas to enhance the latent image formation in the presence of electron–hole pairs with high concentration.

High-resolution measurement of hypernuclear events in a nuclear emulsion with hard X-ray microscopy

High-resolution measurement of hypernuclear events in a nuclear emulsion with hard X-ray microscopy

Three-dimensional density tomography determined from multi-directional muography of the Omuroyama scoria cone, Higashi–Izu monogenetic volcano field, Japan

Scoria cone is one of the basic forms of volcanoes, and clarifying its detailed internal structure and magma movement during its formation is important for understanding the nature of eruptions and also for volcanic disaster mitigation. We conducted a multi-directional muographic survey of the Omuroyama scoria cone, Japan, in order to determine the three-dimensional density structure of the scoria cone. We used a nuclear emulsion detector optimized for multi-directional muography that was installed at 11 sites around the volcano. Muon tracks recorded on emulsion films were read with a high-speed automated readout system. We obtained the three-dimensional density structure by applying a linear inversion to the muographic images, and evaluated the uncertainties. High-density zones were detected in scoria cone. Based on these observations and detailed topographic and geological constraints, we infer that high-density zones are the central, highly welded vent of the scoria cone, three-directional radial dikes extending from the central vent, respectively. We also infer that an E-W-trending dike fed a small lava flow, and that a SSE-NNW-trending dike caused a small flank eruption and produced a crater on the flank of the cone. Our results visualize the three-dimensional internal structure of volcanoes with novel resolution, and thereby demonstrate that the formation process of volcanoes can be discussed in detail. Since it has been difficult to directly detect such clear visualization of the internal structures and eruptive processes in the past, multi-directional muography has resulted in providing one hope for understanding volcanic activity.