Nuclear Emulsion Research Articles

Grey particle characteristics produced in the interaction of 84Kr – Emulsion at 1 A GeV

Abstract This article focused on the emission probability of the grey particles with black particles emitted in the interaction of 84Kr (as a projectile) having incident kinetic energy 1 GeV per nucleon with nuclear emulsion detector (as target detector). This study show that the emission probability of grey particles is depending on the number of emitted black particles.

Study of charged particles produced in the 84Kr + nuclear emulsion interactions at 1 GeV per nucleon

Abstract The main focus of this article is to study the characteristics of charged pions and their correlation with shower particles emitted in the interaction of 84Kr + emulsion at 1 A GeV. Author have also studied the dependence of the average multiplicity of charged pions and shower particles with projectile mass. In this study author observed that the average multiplicity of charged pions and shower particles showing the linear dependency on the projectile mass.

Track formation in nuclear emulsion plates for cosmic-ray imaging with stabilized Ag nanoparticles

In cosmic-ray imaging system with nuclear emulsions, silver halide (AgX) grains capture muon-created electrons to form a latent image composed of small Ag nanoparticles (latent image centers), which could be as small as three atoms. Since it needs such a long time as several months for the grains to capture sufficient number of muon-created electrons for imaging, the stabilization of latent image is inherently important. There are two kinds of latent image fading; the first- and second-order reactions. The former is the oxidation of latent image centers by oxidants, which are not formed by cosmic-ray irradiation, and the latter is the re-halogenation of latent image centers by irradiation-created X2. It was revealed that the latter became to be predominant over the former within several days after irradiation as the volume ratio of gelatin in emulsion layers decreased, indicating that gelatin is very effective to depress this type of latent image fading. Following the previous paper, we have extended our study on the property and behavior of new additives by means of photoelectron spectroscopy to prove the mechanism of the latent image fading with the first-order reaction, according to which a latent image center with electric charge of +1/2 degrades via the repetition of the ionic process (detachment of an Ag+ion) and the electronic process (losing of an electron) one after the other, its electric charge changing to -1/2 and back. The mechanism thus proved has provided several ideas to depress latent image fading in nuclear emulsions for cosmic-ray imaging.

Multiplicity characteristics of the produced shower particles in backward direction-target and projectile dependence

In the present paper a detailed investigation of the multiplicity distribution of the produced shower particles in the backward hemisphere ( $$\theta _{\mathrm {Lab}} \ge 90^{\circ }$$ ) in nuclear emulsion track detector has been carried out. The present study involves interactions of $$^{\mathrm {16}}\hbox {O}$$ and $$^{\mathrm {32}}\hbox {S}$$ projectiles with CNO, AgBr and composite emulsion target at 4.5 AGeV/c. We have compared our results with the results obtained from the analysis of modified Fritiof model. Present study reveals that the production of single shower particle is the most dominant production mode of shower particles in the backward direction. This probability increases with the increase of target mass. The percentage of events having backward shower particles remains almost independent of the projectile beam. But it increases with the increase of target size. Average multiplicity of the shower particles in the backward direction reflects a weaker dependence on the mass number of the projectile beam. Multiplicity distribution of backward shower particles for both experimental and modified Fritiof model can be described by an expression $$\mathrm {P}_{\mathrm {N}} = {\mathrm {P}_{\mathrm {s}}\mathrm {N}_{\mathrm {B}}}^{-{\uplambda }_{\mathrm {B}}}$$ . The fitting parameter $${\uplambda }_{\mathrm {B}}$$ decreases as the target size increases. The decay constant has lower value for the heavier projectile. Higher order multiplicity moments and scaled variance of multiplicity distribution for the backward shower particles showed strong target dependence. Multiplicity distributions of the backward shower particles violate KNO scaling law. Modified Fritiof model failed to reproduce the various features of the multiplicity distribution.

Directionality preservation of nuclear recoils in an emulsion detector for directional dark matter search

Nuclear emulsion is a well-known detector type proposed also for the directional detection of dark matter. In this paper, we study one of the most important properties of direction-sensitive detectors: the preservation by nuclear recoils of the direction of impinging dark matter particles. For nuclear emulsion detectors, it is the first detailed study where a realistic nuclear recoil energy distribution with all possible recoil atom types is exploited. Moreover, for the first time we study the granularity effect on the emulsion detector directional performance. As well as we compare nuclear emulsion with other directional detectors: in terms of direction preservation nuclear emulsion outperforms the other detectors for WIMP masses above 100 GeV/c2.

Backward shower particle production in high energy nucleus–nucleus collisions — an outlook to centrality dependence

A detailed study on the centrality dependence of the different aspects multiplicity distribution of the shower particles produced in the backward direction ([Formula: see text] in nuclear emulsion track detector has been carried out for [Formula: see text]Ne-emulsion interactions at 4.1 AGeV/c. Depending on the values of the total charges or sum of the charges of noninteracting projectile fragments, event samples were classified into four centrality classes. From the analysis presented in this paper, qualitative information about the assembly of shower particles in the backward direction has been extracted.

First measurement using a nuclear emulsion detector of theνμcharged-current cross section on iron around the 1 GeV energy region

AbstractWe have carried out $\nu_{\mu}$ charged-current interaction measurement on iron using an emulsion detector exposed to the T2K neutrino beam in the J-PARC neutrino facility. The data samples correspond to $4.0 \times 10^{19}$ protons on target, and the neutrino mean energy is 1.49 GeV. The emulsion detector is suitable for precision measurements of charged particles produced in neutrino–iron interactions with a low momentum threshold thanks to a thin-layered structure and sub-$\mu$m spatial resolution. The charged particles are successfully detected, and their multiplicities are measured using the emulsion detector. The cross section was measured to be $\sigma^{\mathrm{Fe}}_{\mathrm{CC}} = (1.28 \pm 0.11({\mathrm{stat.}})^{+0.12}_{-0.11}({\mathrm{syst.}})) \times 10^{-38} \, {\mathrm{cm}}^{2}/{\mathrm{nucleon}}$. The cross section in a limited kinematic phase space of induced muons, $\theta_{\mu} < 45^{\circ}$ and $p_{\mu} > 400 \, {\rm MeV}/c$, on iron was $\sigma^{\mathrm{Fe}}_{\mathrm{CC \hspace{1mm} phase \hspace{0.5mm} space}} = (0.84 \pm 0.07({\mathrm{stat.}})^{+0.07}_{-0.06}({\mathrm{syst.}})) \times 10^{-38} \, {\mathrm{cm}}^{2}/{\mathrm{nucleon}}$. The cross-section results are consistent with previous values obtained via different techniques using the same beamline, and they are reproduced well by current neutrino interaction models. These results demonstrate the capability of the detector in the detailed measurement of neutrino–nucleus interactions around the 1 GeV energy region.

Development of a new tracking detector with fine-grained nuclear emulsion for sub-MeV neutron measurement

Abstract We have developed a new sub-MeV neutron detector with high position resolution, energy resolution, and directional sensitivity, and low background. The detector is based on a super-fine-grained nuclear emulsion, called a nano-imaging tracker (NIT), and it is capable of detecting neutron-induced proton recoils as tracks through topological analysis with sub-micrometric accuracy. We used a type of NIT with AgBr:I crystals of ($98 \pm 10$) nm size dispersed in gelatin. First, we calibrated the performance of the NIT device for detecting monochromatic neutrons with sub-MeV energy generated by nuclear fusion reactions, and the detection efficiency for recoil proton tracks of more than 2 $\mu$m range was consistently 100% (the 1 $\sigma$ lower limit was 83%) in accordance with expectations from manual analysis. In addition, the recoil energy and angle distribution obtained good agreement with kinematical expectations. The primary neutron energy was reconstructed using these, and it was evaluated as 42% full width at half maximum at 540 keV. Furthermore, we demonstrated a newly developed automatic track recognition system dedicated to track ranges of more than a few micrometers. It achieved a recognition efficiency of ($74 \pm 4$)%, and the recoil energy and angle distribution obtained good agreement with manual analysis. Finally, it indicated a very high rejection power for $\gamma$-rays.

Devendra Lal. 14 February 1929—1 December 2012

Devendra Lal was an Indian nuclear physicist who began his career studying particle physics while a student at the Tata Institute of Fundamental Research (TIFR) in Bombay, using tracks in nuclear emulsions to study cosmic ray particles and their interactions. He soon moved on to the search for radionuclides produced in the atmosphere by cosmic ray bombardment, independently (with colleagues) discovering radioisotopes of Be, P and Si and using them as geophysical tracers for atmospheric, meteorological and oceanographic processes. His career revolved principally around multiple aspects of cosmic rays, employing theory and experiment to examine their flux, chemical composition and energy spectrum, both at present and in the past through (for example) studies of particle tracks in the minerals of meteorites and lunar samples. He played a major role in developing approaches for the use of terrestrial cosmic-ray-produced isotopes as dating tools and tracers for a wide range of Earth processes, from biological cycles in the ocean to landscape evolution and ice ablation in the Antarctic. At various stages of his career Lal was professor at TIFR and led the geophysics group there, was professor and director of the Physical Research Laboratory in Ahmedabad, India, and was professor at the Scripps Institution of Oceanography, University of California San Diego. He was elected fellow of numerous scientific organizations and academies internationally, and was the recipient of many scientific awards and prizes.

The major achievements of the OPERA experiment and its legacy

The OPERA experiment was designed to discover the [Formula: see text] appearance in a pure [Formula: see text] beam, resulting from neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of an emulsion/lead target complemented by electronic detectors and was exposed, from 2008 to 2012, to the (CERN Neutrinos to Gran Sasso (CNGS)) beam, an almost pure [Formula: see text] beam with a baseline of 730 km, collecting a total of [Formula: see text] protons on target. OPERA was unique in its capability of detecting all three neutrino flavors. OPERA discovered [Formula: see text] oscillations in appearance mode with a significance of [Formula: see text]. In this review, we report the major achievements of the OPERA experiment and its legacy in the nuclear emulsion technology.

Neutron Imaging Using a Fine-Grained Nuclear Emulsion.

A neutron detector using a fine-grained nuclear emulsion has a sub-micron spatial resolution and thus has potential to be applied as high-resolution neutron imaging. In this paper, we present two approaches to applying the emulsion detectors for neutron imaging. One is using a track analysis to derive the reaction points for high resolution. From an image obtained with a 9 μm pitch Gd grating with cold neutrons, periodic peak with a standard deviation of μm was observed. The other is an approach without a track analysis for high-density irradiation. An internal structure of a crystal oscillator chip, with a scale of approximately 30 μm, was able to be observed after an image analysis.

Characteristics of the grey particles emission at relativistic energy

The theme of present analysis is to focus on the emission characteristics of grey particles emitted in 4π angle, forward hemisphere angle (θ < 90°) (FHS) and backward hemisphere angle (θ ≥ 90°) (BHS). We have studied the average multiplicity variation of grey particles for the events emitted from the reaction of projectiles with CNO and AgBr target nuclei of nuclear emulsion. We have also investigated the emission probability of grey particles with projectile mass in between the range of 1 and 207. In this analysis we have observed that the emission probability of grey particles is higher in forward hemisphere angle as compared to backward hemisphere angle. We have also observed that the average multiplicity of grey particles is independent on the projectile mass and incident energy.

X-ray topography of crystallographic defects in wide-bandgap semiconductors using a high-resolution digital camera

A high-resolution CMOS camera equipped with a scintillator and relay lenses was used to record X-ray topographic images of wide-bandgap semiconductor wafers, including 4H-SiC, GaN, AlN, and β-Ga2O3. The images were compared with those recorded with nuclear emulsion plates (NEPs) and a CCD camera at the same sample site. Fine structures of dislocation contrasts, which allowed for accurate identification of the dislocation types, could be observed using the CMOS camera. The results suggest that the CMOS camera can provide high-quality images that are comparable with the NEPs; hence, the reported approach is a promising one for real-time dislocation observation in power devices under operation.

Nuclear Emulsion Technology in Modern Neutrino Experiments

Nükleer emülsiyon, parçacık fiziği deneylerinde kullanılan önemli bir parçacık algıcıdır. Bu tekniğin kullanımı 1900’lü yıllarda başlamış ve günümüze kadar ilerleyerek gelmiştir. Nükleer emülsiyon, sahip olduğu yüksek uzaysal çözünürlüğü sayesinde yüklü parçacıkların izlerinin takip edilmesini kolaylaştırmaktadır. Ayrıca üç boyutlu etkileşimlerin görüntülerini yeniden oluşturma, hatta enerji ve momentum ölçümlerinin yapımına da olanak sağlamaktadır. Bu özellikleri nedeniyle teorik ve deneysel parçacık fiziğine önemli katkılar getirmektedir. Günümüzde nükleer emülsiyon tekniği halen çeşitli araştırmalarda geliştirilerek kullanılmaktadır. Tasarlanan yeni deneylerde nükleer emülsiyonlar hızlandırıcılarda oluşturulan parçacık demeti önüne yerleştirilerek elde edilen verilerden atom altı parçacıklar, birbirleriyle olan ilişkileri, etkileşimleri ve karakteristik özellikleri belirlenmeye çalışılmaktadır. Bu amaçla gerçekleştirilen deneyler arasında CHORUS, DONUT, PEANUT ve OPERA deneyleri bulunmaktadır. Nötrinonun doğasını anlamak üzere tasarlanan bu deneylerde nükleer emülsiyon teknolojisi başarıyla kullanılmış ve henüz tasarım aşamasına olan SHIP deneyinde de yine nükleer emülsiyon teknolojisinin kullanılması planlanmaktadır. Bu çalışmada parçacık fiziğinde yaygın kullanımı ve büyük önemi olan nükleer emülsiyon teknolojisinin gelişim aşamaları, kullanılan materyal ve yöntemler modern nötrino deneyleri ışığında incelenmiştir. Önümüzdeki yıllarda nükleer emülsiyon teknolojisinin giderek gelişeceği, yeni nesil deneylere ve araştırmalara yön vererek parçacık fiziğinde önemli sonuçlara ulaşılması beklenmektedir.

CNN-based event classification of alpha-decay events in nuclear emulsion

Alpha-decay events in a nuclear emulsion are standard calibration sources for the relation between the track length and the kinetic energy in each emulsion sheet. We developed an efficient classifier that sorts such alpha-decay events from various vertex-like objects in an emulsion using a convolutional neural network (CNN). We trained the CNN using 15885 images of vertex-like objects, including 906 alpha-decay events, and tested it using a dataset of 46948 images including 255 alpha-decay events. The precision and recall scores of the classification using the previous method without a CNN for the same dataset were 0.081 ± 0.006 and 0.788 ± 0.056, respectively. In contrast, our trained models achieved an average precision score of 0.760 ± 0.006 for the test dataset, after extensively tuning the hyperparameters of the CNN. Moreover, for the model obtained, the discrimination threshold of the classification can be adjusted arbitrarily according to the trade-off between the precision and recall scores. Furthermore, the developed classifier obtained a precision of 0.571 ± 0.017 when the recall score was assigned a value of 0.788. Finally, the developed CNN method reduced the need for additional human visual inspection, required after classification, by a factor of approximately 1/7, compared to the former method without a CNN, proving the feasibility of the proposed classifier.

NA65 (DsTau) experiment: Tau neutrino production study at the CERN SPS

The NA65/DsTau experiment is an approved CERN experiment with the scope to investigate the tau neutrino production using nuclear emulsion. The production process of tau neutrino is important in the precise measurement of the cross-section of tau neutrinos, which has a positive impact on other experiments. A pilot run was conducted in 2018 and the analysis is underway. Preparations are also ongoing for physics runs in 2021 and 2022.

Super-resolution high-speed optical microscopy for fully automated readout of metallic nanoparticles and nanostructures

We have designed a fully automated optical microscope running at high-speed and achieving a very high spatial resolution. In order to overcome the resolution limit of optical microscopes, it exploits the localized surface plasmon resonance phenomenon. The customized setup using a polarization analyzer, based on liquid crystals, produces no vibrations and it is capable of probing isolated nanoparticles. We tested its performance with an automated readout using a fine-grained nuclear emulsion sample exposed to 60 keV carbon ion beam and, for the first time, successfully reconstructed the directional information from ultra-short tracks produced by such low-energetic ions using a solid-state tracking detector.

Observation of a Liquid–Gas Phase Transition upon Antiproton Annihilation in a Nuclear Emulsion

Five hundred events of antiproton stopping and annihilation in nuclear emulsion were observed. A description of the equation of state for nuclear matter in terms of the van de Waals equation made it possible to determine the temperature dependence of the pressure and density and to obtain an estimate for the boundary of the spinodal region in which a uniform state undergoes an instantaneous transition from to a uniform state to a mixture of two phases—fragments and a nuclear gas of nucleons observed experimentally.

Biological Detection of Physical Factors Related to the High-Current Electric Explosion of Conductors in a Vacuum

The effect physical factors associated with the high-current electric explosion of conductors in a vacuum (pulsed magnetic field, light exposure, radiation leaving specific tracks on nuclear emulsions and other materials) have on biological systems is studied. The effect is assessed from the level of nuclear DNA damage in human peripheral blood leukocytes, the frequency of chromosomal aberrations in the dividing cells of an onion root, the growth rate of green unicellular algae, and the germination and growth rate of plant seeds.

First measurement of ν¯μ and νμ charged-current inclusive interactions on water using a nuclear emulsion detector

This paper reports the track multiplicity and kinematics of muons, charged pions, and protons from charged-current inclusive $\bar{\nu}_{\mu}$ and $\nu_{\mu}$ interactions on a water target, measured using a nuclear emulsion detector in the NINJA experiment. A 3-kg water target was exposed to the T2K antineutrino-enhanced beam with a mean energy of 1.3 GeV. Owing to the high-granularity of the nuclear emulsion, protons with momenta down to 200 MeV/$c$ from the neutrino-water interactions were detected. We find good agreement between the observed data and model predictions for all kinematic distributions other than the number of charged pions. These results demonstrate the capability of measurements with nuclear emulsion to improve neutrino interaction models.