bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of the photoinduced birefringence in PAZO azopolymer doped with ZnO via electrospray deposition
Authors: Mateev G , Marinov G , Nedelchev L , Nazarova D , Stoykova E , Babeva T
Published: June 2020

We present a study of the birefringence photoinduced in thin nanocomposite films of an azopolymer (PAZO) doped with different concentrations of nanoparticles (NPs) of ZnO with spherical shape and size in the range 40 – 100 nm. The nanocomposite thin films were prepared by electrospray deposition of ZnO over a thin azopolymer film with a thickness below 200 nm. The different NPs concentrations were obtained through different electrospray deposition times varied from 0 to 10 minutes. Birefringence was induced by a He-Cd laser at a wavelength of 442 nm and measured by a probe diode pumped solid state (DPSS) laser at 635 nm. The birefringence dependence on the ZnO NP deposition time reached its maximum for a deposition time of 90 s.
Formation and characterization of Al-Hf alloys by selective electron-beam surface alloying
Authors: Valkov S , Petrov P
Published: June 2020

We report electron-beam surface alloying of Al substrates with Hf. The Al substrates were covered by a Hf coating with a thickness of 2 μm; the samples were alloyed by means of a scanning electron beam with circular geometry of the beam deflection. The phase composition of the obtained specimens was studied by X-ray diffraction (XRD); their microstructure and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The results showed that the phase composition did not depend on the speed of sample motion. However, their microstructure was significantly finer and more homogeneous in the case of the lower speed of motion V
1 = 0.5 cm/s in comparison with the higher speed V
2 = 1 cm/s.
Comparative measurements of solar UV irradiation at the high-mountain stations of BEO-Moussala (BG) and NAO-Rozhen (BG)
Authors: Tyutyundzhiev N , Angelov Ch , Lovchinov K , Nitchev Hr , Arsov T , Mutafov A
Published: June 2020

Damaging UV radiation is an important object of investigation related to its impact on biological species. Data acquired at high-altitude stations reveal dangerous events of incident UV radiation reaching the Earth surface. Continuous multi-UV spectral measurements by open-source equipment could further deepen the knowledge of solar light propagation and the events of radiation transfer and atmospheric absorption processes. This report describes recent results on high-resolution UVA, UVB, UVC measurements of solar UV radiation at the mountain stations in Bulgaria.
Antibacterial silver nanolayers for coatings on surgical and microsurgical instruments
Authors: Koev K , Donkov N , Naidenski H , Nikov R , Kusovski V , Nurgaliev T , Avramov L
Published: June 2020

In this paper, we describe the antibacterial action of Ag-doped Al2O3 nanolayers deposited by RF reactive magnetron sputtering on stainless-steel surgical and microsurgical instruments. Synthesizing Ag/Al2O3 protective coatings is necessary for suppressing the infections caused by pathogenic microorganisms following the application of surgical instruments. We further conducted microbiological studies on the action of the nanocomposite Ag/Al2O3 layers against Gram-positive and Gram-negative bacteria (Staphylococcus aureus and Escherichia coli). The microbiological studies conducted proved the antibacterial effect of the nanocomposite Ag/Al2O3 layers, the strongest effect against Escherichia coli and Staphylococcus aureus being observed after 48 hours of exposure. Also, the Ag/Al2O3 nanolayers showed no cytotoxic effect. Our experimental findings suggest a very promising application of such antibacterial Ag/Al2O3 nanolayers regarding the reduction of infections when stainless-steel surgical and microsurgical instruments are used.
Dielectric and magnetic properties of Sr3Co2Fe24O41 thin hexaferrite samples in the microwave range
Authors: Dankov P , Kolev S , Koutzarova T
Published: June 2020

We present studies on the changes of the dielectric properties of 0.7 – 1.2-mm thick-layers of Sr3Co2Fe24O41 Z-type hexaferrite in the frequency range 5 – 40 GHz; to the best of our knowledge, for the first time we used a combination of two methods – a resonance method, which yields infomation on the dielectric and magnetic anisotropies of the samples, and a broadband transmission-line method – covered coplanar and microstrip lines. We measured an increase of the dielectric constant and dielectric loss tangent above 20 GHz and a measurable anisotropy of the permittivity and permeability. The changes in the two parameters were also investigated (a magneto-electric effect was observed) in an external dc magnetic field in directions parallel and perpendicular to the sample at room temperature. The investigations presented are complex and intricate and should be considered as a first step in the characterization of thick Sr3Co2Fe24O41 Z-type hexaferrite slabs above 3 GHz up to the mm-wave range.
Dilute nitride InGaAsN and GaAsSbN layers grown by liquid-phase epitaxy for photovoltaic applications
Authors: Donchev V , Milanova M , Georgiev S , Kostov K L , Kirilov K
Published: June 2020

Dilute nitride InGaAsN and GaAsSbN layers are grown by low-temperature liquid-phase epitaxy (LPE) on GaAs substrates and characterized in view of application in solar cells. The composition of the layers is determined by energy-dispersive X-ray spectroscopy. X-ray photoelectron spectroscopy measurements confirm the Sb content and provide information about the chemical bonding of the N atoms. The band gap values at room temperature assessed from surface photo-voltage and photoluminescence measurements are in good agreement. The experimental results show that the layers exhibit reproducible properties, including a good optical quality and a photosensitivity red limit extended in comparison to GaAs down to about 1.33 – 1.37 eV for InGaAsN and 1.19 – 1.23 eV for GaAsSbN layers. The results obtained highlight the capacity of the LPE for growing dilute nitride layers with good optical quality for photovoltaic applications.
Hybrid Ag/ZnO nanostructures for SERS detection of ammonium nitrate
Authors: Koleva M E , Nedyalkov N N , Nikov Ru G , Nikov Ro G , Nuzhdin V I , Valeev V F , Rogov A M , Stepanov A L
Published: June 2020

Ag/ZnO composite nanostructures are produced by combined laser and ion implantation techniques. The ZnO layers are grown on SiO2 (001) and Al2O3 (r-cut) substrates by pulsed laser deposition (PLD) in vacuum and in oxygen ambient using a third-harmonic Nd:YAG laser. The ion implantation allows the introduction of Ag nanoparticles (NPs) in the surface of the ZnO matrix. These NPs are incorporated into the ZnO matrices to fabricate metal-semiconductor nanocomposites with the aim of manipulating their functionalities, exploiting the characteristics of both the matrix and the metal NPs. The composite samples are modified by laser annealing at 355 nm and 532 nm. The changes are investigated in the plasmon resonance absorption of the nanostructures before and after the annealing. The influence is explored of the different substrates used and the deposition conditions of ZnO growth on the properties of Ag/ZnO. The nanostructures obtained are efficient as SERS substrates for detection of ammonium nitrate under laser excitation at 633 nm. The SERS enhancement is attributed to the synergistic interactions between the plasmonic coupling among the surface embedded AgNPs and the enhanced charge transfer properties of the ZnO.
Light irradiation effect on the gas response of pure and noble-metal-doped ZnO sensors
Authors: Atanasova G , Dilova T , Dikovska A Og , Nedyalkov N N
Published: June 2020

Highly porous pure and noble metal (Ag, PdAg and Pd) doped ZnO nanostructures were fabricated by pulsed laser deposition (PLD) in air at atmospheric pressure (in open air). This technology leads to the formation of nanostructures composed of nanoparticles or nanoaggregates. The as-deposited nanostructures possess a large surface-to-volume ratio, which makes them suitable for gas-sensor applications. In this work, we demonstrated the response of pure ZnO and of Ag-ZnO, Pd-ZnO and PdAg-ZnO sensor elements to NH3, CO, ethanol, and acetone exposure under UV light irradiation. The effect was studied of simultaneous UV and red or green light irradiation on the sensor element’s response, selectivity, and response and recovery time. It was found that irradiation by UV and red light has the effect of improving the Ag-ZnO sensor’s response to CO exposure and suppressing its response to NH3, ethanol and acetone. The same behavior was exhibited by the pure ZnO sensor element irradiated simultaneously by UV and green light.
Comparison of ALD-grown thin ZnO films with various thicknesses for NO2 sensing
Authors: Boyadjiev S I , Georgieva V , Szilágyi I M , Vergov L , Georgieva B , Paskaleva A
Published: June 2020

Thin zinc oxide (ZnO) films of various thicknesses were characterized and compared in terms of their suitability to gas sensor applications. Applying atomic layer deposition (ALD), very thin ZnO films were deposited on quartz resonators, and their gas sensing properties were studied using a quartz crystal microbalance (QCM). The ZnO thin films were prepared using diethyl zinc and water as precursors. The crystal structure of the films was studied by X-ray diffraction (XRD), and their surface was observed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX) used to study the films’ composition. Films of thickness of ~10 – 80 nm were deposited on quartz resonators with Au electrodes and the QCM method was used to build highly sensitive gas sensors. These were tested for sensitivity to various concentrations of NO2. Although some of the films were very thin, they were sensitive to NO2 already at room temperature and could register reliably as low concentrations as 50 ppm, while the sorption was fully reversible and the sensors could be fully recovered. With the technology presented, manufacturing of QCM gas sensors is simple, fast and cost-effective, and suitable for application in energy-effective portable equipment for real-time monitoring of NO2 in the automotive industry or environmental protection.
Cryostat for cooling samples in the study of low-temperature structural and magnetic phase transitions by neutron diffraction
Authors: Popov E P , Chernikov A N , Beskrovnyi A I , Waliszewski J , Mirzayev M N
Published: June 2020

A vertical cryostat was developed built around a Sumitomo RDK-101D cold head. The cryostat is intended for investigating the structure and phase transformations of different materials via neutron diffraction experiments on samples under high vacuum of up to 10−5 mbar. A working temperature of the sample close to 2 K was reached. The drift diameter of the head is 54 mm, making it possible to cool samples with a height of 55 mm and 15 mm in diameter. Test measurements were conducted and illustrative spectra were recorded on the example of a sample of HoFeO3. The cryostat was designed and manufactured at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research.
Femtosecond laser modification of the optical properties of glass containing noble-metal nanoparticles
Authors: Nikov Ro , Nedyalkov N , Koleva M , Stankova N , Iordanova E , Yankov G , Aleksandrov L , Iordanova R
Published: June 2020

The paper presents results on femtosecond laser irradiation-induced modification of the optical properties of a composite material – gold nanoparticles embedded into a borosilicate glass host. The process is initiated by laser pulses delivered by a Ti:sapphire laser system with pulse duration of 35 fs. The glass samples are prepared by melt quenching with gold added as hydrogen tetrachloroaurate (III) hydrate to the initial composition. Post-fabrication annealing leads to a homogeneous formation of nanoparticles in the glass; varying the annealing parameters results in producing nanoparticles with different sizes and shapes. The laser irradiation of the samples induces significant modification of the optical spectra of the glass through changes of the nanoparticles characteristics. The effects are studied of the laser fluence, laser wavelength and laser pulses number. The heat diffusion equation is applied to estimate the temperature evolution and explain the modifications observed. The results demonstrate this technique’s efficiency in modifying the nanoparticles properties with a high 3D spatial resolution, which can be useful in fabrication of integrated optical systems.
Ultra-fast laser surface texturing of β-tricalcium phosphate (β-TCP) ceramics for bone-tissue engineering applications
Authors: Daskalova A , Lasgorceix M , Bliznakova I , Angelova L , Hocquet S , Leriche A , Trifonov A , Buchvarov I
Published: June 2020

β-tricalcium phosphate (β-TCP) has provoked particular attention as graft for bone regeneration applications due to its excellent biocompatibility and biodegradability. In this work, we investigated the interaction of femtosecond laser radiation with β-TCP pellets by varying the output laser parameters in order to estimate their influence on the surface roughness and on the morphological and topographical properties of the substrate before and after laser treatment. Femtosecond laser micro-processing for pulse duration of τ = 30 fs and 130 fs was performed by varying the number of laser pulses N = 1 – 100, at λ = 800 nm and a variable repetition rate. The microstructural changes induced were characterized by confocal microscopy. Comparing the experimental results, we concluded that the femtosecond laser method can be applied for biomaterials surface functionalization with a high-level of precision.
Preliminary results on non-linear effects in Au-ion-doped glass materials irradiated by femtosecond laser pulses
Authors: Yankov G , Iordanova E , Nedyalkov N , Zamfirescu M
Published: June 2020

Our research was motivated by the specific properties of noble-metal nanoparticles and their wide applications. The resonance frequency for noble-metal nanostructures is in the near-UV and visible spectral ranges, where most of the commercially-available lasers oscillate. This makes these materials attractive candidates for studying their properties in view of efficient applications. We investigated filaments formation in Au-ion-doped glass materials, transparent in the visible range, during irradiation by femtosecond laser pulses. Second harmonic generation in the media was observed as well. This proved the formation of polycrystalline structures inside the media after femtosecond laser radiation. Further, self-phase modulation and continuum were observed. Thus, the nonlinearity of the media is higher than that of glass not doped with noble-metal particles. The nonlinear effects in the samples were investigated in terms of the laser beam parameters. The laser energy applied was between 10 – 40 μJ. The wavelengths used were in the range 240 – 2600 nm, as generated by an optical parametric amplifier system (TOPAS). The regenerative Ti:Sapphire amplified laser system emits at a central wavelength of 800 nm with a pulse duration of 35 fs and 1-kHz repetition rate.
Measurement and control of the substrate temperature in vertical graphene nanosheets deposition
Authors: Vachkov V , Kiss’ovski Zh
Published: June 2020

The characteristics of the microwave surface-wave plasma discharge at atmospheric pressure and the control of the gas mixture (Ar/H2/CH4) in the deposition chamber, together with the temperature of the metallic substrate, are important parameters in the processes of deposition of vertical graphene nanosheets. Since obtaining carbon nanostructures necessitates regulating the substrate temperature in the range 550 – 980 °C, we developed an electronic system based on an Arduino Uno microcontroller. It was designed to automatically measure and control the temperature of the substrate heater with the capability of varying smoothly the temperature by a PID-regulator. The measurements were carried out by a K-type thermocouple, whose hot end was placed at the point of measuring the temperature. The resulting thermoelectric voltage was amplified by a MAX 31855 amplifier, followed by processing by the microcontroller and subsequent determination of the temperature. This system offers the possibility of controlling accurately the temperature as required by the regime of deposition.
Effect of the inert/reactive gases ratio and bias voltage on the tribological properties of VN coatings
Authors: Rabadzhiyska S , Ormanova M , Ivanov N , Petrov P
Published: June 2020

Vanadium nitride (VN) thin films were deposited on 304L high-speed stainless steel (HSS) specimens using a DC reactive magnetron sputtering system. The experiments were carried out with a varying ratio of reactive/inert gases of 1.7, 2.3 and 3 and a negative substrate bias of –30 V, –40 V and –50 V. Grazing incidence X-ray diffraction was used to characterize the structure of the layers produced. The coatings’ roughness and tribological behavior was evaluated.
Modification of carbon black by thermal treatment in air atmosphere
Authors: Milenov T , Avramova I , Avdeev G , Mladenoff J , Pishinkov D , Genkov K , Zyapkov A , Russev S , Nikolov A , Stankova N , Velikova R , Kolev S , Valcheva E
Published: June 2020

We modified carbon black (CB) with a large surface area (ENSACO 350 GRANULAR) by acetone and further thermal treatment. The pristine and the modified CB were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Raman spectroscopy. The acetone treatment increases the content of oxygen-containing radicals in CB. The thermal annealing was performed at temperatures ranging from 250 °C to 1080 °C for three hours in air atmosphere. The powder XRD patterns revealed that the broad complex peak centered at about 2θ = 24.7 – 24.8°, which arises from graphitic-ordered sp2-hybridized carbon, shifts to its usual position at 2θ = 26.2° as the annealing temperature is increased. We concluded that the above results pointed to a relative decrease in the number of 3D graphitic nano-crystals and an increase in the predominantly 2D ones. The Raman studies confirmed the above conclusions.
Structural study of thick hexaferrite films
Authors: Koutzarova T , Georgieva B , Kolev S , Ghelev Ch , Krezhov K , Kovacheva D , Vertruyen B , Closset R , Tran L-M , Zaleski A
Published: June 2020

We present details of the microstructural properties of Y- (Ba2Mg2Fe12O22, Ba0.5Sr1.5Zn2Fe12O22, Ba0.5Sr1.5Zn2Al0.08Fe11.92O22) and Z-type (Sr3Co2Fe24O41) hexaferrite thick films deposited by screen printing and drop casting on unpolished polycrystalline Al2O3 substrates. The hexaferrites thick films obtained by drop casting exhibited considerable roughness and porousness compared with those obtained by screen printing. We found that the powders’ morphology significantly affects the microstructure of the thick films formed by screen printing. The microstructural analysis of the thick films shows that their microstructure differs from that of the powders. Further, during the annealing process the grains in the thick films grow and form hexagonal particles, the latter having the largest size, best shape and being best observed in the case of the Ba2Mg2Fe12O22 film.
Introduction to KAON2019 – Experiments –
Authors: Yamanaka T
Published: June 2020

The KAON2019 is the 11th conference in the series which started in 1988. Many kaon experiments have evolved during these years. In this talk, challenges and developments of the experiments for Re(ϵ
′/ϵ) and rare

K
→
π
ν

ν
¯

decays are reviewed.
CP violation in beauty and charm at LHCb
Authors: Romero Lamas M
Published: June 2020

Precision measurements of CP violating observables in the decays of b and c hadrons are powerful probes to search for physics beyond the Standard Model. The most recent results on CP violation in the decay, mixing and interference of both b and c hadrons obtained by the LHCb Collaboration with Run I and years 2015-2016 of Run II are presented, including the first observation of CP violation in the charm system. In particular world best constraints and world first measurements are provided for CKM elements, unitarity angles and charm parameters. Prospects for future sensitivities are also discussed.
K → ππ decay, ε
′ and the RBC-UKQCD kaon physics program
Authors: Christ N H
Published: June 2020

An overview of the kaon physics program of the RBC and UKQCD collaborations will be presented with a focus on the lattice calculation of K → ππ decay and the direct CP violation parameter ε
′. We will describe substantial improvements to our earlier 2015 K → ππ calculation, including the use of three independent ππ interpolating operators and the results we obtain for I = 0 ππ scattering for energies at and below the kaon mass. While the new result for ϵ
′ is not yet complete, the enhanced statistics and improved analysis that underlies our expanded calculation will be presented.
Latest Results on Lattice Calculation Concerning K → π
ℓ
+
ℓ
− Decays
Authors: Boyle P , Jüttner A , HÓgáin F Ó , Portelli A
Published: June 2020

The K → π
ℓ
+
ℓ
− decay is a flavor changing neutral current process which is forbidden at tree level in the Standard Model. This suppression causes the decay to be sensitive to potential New Physics. The decay channels are dominated by long-distance contributions, which require non-perturbative methods of investigation. Previous lattice calculations by the RBC and UKQCD collaborations, at unphysical kaon/pion masses, have successfully extracted the matrix elements needed to describe the form factor of the decays. A new lattice calculation, on a gauge configuration with m

π
≈ 140 MeV and m

K
≈ 500 MeV, is underway and will be discussed here.
K→πνν¯

and new physics in the neutrinos
Authors: Valencia G
Published: June 2020

We discuss generic effects of new physics on the rare decay modes

K
L

→

π
0

ν

ν
¯

and

K
+

→

π
+

ν

ν
¯

from the point of view of the neutrino sector. We pay particular attention to the cases of right handed neutrino couplings and neutrino lepton flavour violating interactions. The first of these examples requires the existence of a new light (sterile) right-handed neutrino and its contribution to both rates is always additive to the standard model. It is motivated as a possible solution to the so called charged B anomalies. The case of neutrino lepton flavour violating couplings produces interesting constraints on new physics which are competitive with those from standard searches for charged lepton flavour violating in kaons and in some cases better than those from tau decay.
The Optimal Strategy for ε
′/ε in the SM: 2019
Authors: Buras Andrzej J
Published: June 2020

Following the recent analysis done in collaboration with Jason Aebischer and Christoph Bobeth, I summarize the optimal, in our view, strategy for the present evaluation of the ratio ε
′/ε in the Standard Model. In particular, I emphasize the importance of the correct matching of the long-distance and short-distance contributions to ε
′/ε, which presently is only achieved by RBC-UKQCD lattice QCD collaboration and by the analytical Dual QCD approach. An important role play also the isospin-breaking and QED effects, which presently are best known from chiral perturbation theory, albeit still with a significant error. Finally, it is essential to include NNLO QCD corrections in order to reduce unphysical renormalization scheme and scale dependences present at the NLO level. Here µ

c
in m

c
(µ

c
) in the case of QCD penguin contributions and µ

t
in m

t
(µ

t
) in the case of electroweak penguin contributions play the most important roles. Presently the error on ε
′/ε is dominated by the uncertainties in the QCDP parameter

B
6

(
1
/
2
)

and the isospin-breaking parameter

Ω
^

eff

. We present a table illustrating this.
Semileptonic Hyperon Decays at LHCb
Authors: Brea Rodríguez A
Published: June 2020

Semileptonic Hyperon Decays (SHD) allow to test Beyond the Standard Model physics with operators not accessible to kaon decays. In this document we will discuss the prospects of the LHCb experiment to improve the existing measurement of muonic SHD. A background rejection study has been made using the LHCb simulation in order to investigate the power to distinguish between the

Λ
0

→
p

μ
−

ν
¯

decay and its main background, the Λ0 → pπ
− decay. Two variables were explored, and their rejection power was estimated by applying a selection criteria. In addition, the estimated

Λ
0

→
p

μ
−

ν
¯

yield at LHCb was calculated.
Studies of kaonic atoms at the DAΦNE collider: from SIDDHARTA to SIDDHARTA-2
Authors: Sirghi Diana , Amirkhani Aidin , Baniahmad Ata , Bazzi Massimiliano , Bosnar Damir , Bragadireanu Mario , Carminati Marco , Cargnelli Michael , Clozza Alberto , Curceanu Catalina , De Paolis Luca , Del Grande Raffaele , Fabbietti Laura , Fiorini Carlo , Guaraldo Carlo , Iliescu Mihail , Iwasaki Masaiko , Sandri Paolo Levi , Marton Johann , Miliucci Marco , Moskal Paweł , Niedźwiecki Szymon , Okada Shinji , Pietreanu Dorel , Piscicchia Kristian , Scordo Alessandro , Silarski Michal , Sirghi Florin , Skurzok Magdalena , Spallone Antonio , Tüchler Marlene , Doce Oton Vazquez , Widmann Eberhard , Zmeskal Johann
Published: June 2020

The DAΦNE electron-positron collider of the Laboratori Nazionali di Frascati of INFN is a worldwide unique low-energy kaon source and for this reason is suitable for low-energy kaon physics like kaonic atoms and kaon-nucleons/nuclei interaction studies. Kaonic atoms are atomic systems where an electron is replaced by a negatively charged kaon, containing the strange quark, which interacts in the lowest orbits with the nucleus also by the strong interaction. As a result, their study offers the unique opportunity to perform experiments equivalent to scattering at vanishing relative energy. This allows to study the strong interaction between the antikaon and the nucleon or the nucleus “at threshold”, without the need of ad hoc extrapolation to zero energy, as in scattering experiments. The most precise kaonic hydrogen measurement to date, together with an exploratory measurement of kaonic deuterium, were carried out by the SIDDHARTA collaboration at the DAΦNE electron-positron collider of LNF-INFN, by combining the excellent quality kaon beam delivered by the collider with new experimental techniques, as fast and precise Silicon-Drift X-ray Detectors. The measurement of kaonic deuterium will be realized in the near future by SIDDHARTA-2, a major upgrade of SIDDHARTA.
Studies of low-energy K− hadronic interactions with light nuclei by AMADEUS
Authors: Del Grande R , Bazzi M , Bragadireanu A M , Bosnar D , Cargnelli M , Clozza A , Curceanu C , De Paolis L , Fabbietti L , Ghio F , Guaraldo C , Iliescu M , Iwasaki M , Levi Sandri P , Marton J , Miliucci M , Moskal P , Okada S , Piscicchia K , Ramos A , Scordo A , Silarski M , Sirghi D L , Sirghi F , Skurzok M , Spallone A , Vazquez Doce O , Widmann E , Wycech S , Zmeskal J
Published: June 2020

The AMADEUS collaboration aims to provide precise experimental information on the K− strong interaction with nucleons in the low-energy regime. The step 0 of AMADEUS consists in the re-analysis of the data collected with the KLOE detector at the DAΦNE collider during the 2004/2005 data taking campaign. The absorptions of low-momentum K−s in the nuclei contained in the detector and the beam pipe setup (H, 4He, 9Be and 12C) are investigated. Information on the K− single and multi-nucleon interactions are extracted from the study of the Λπ
− and p correlated production in the final state.
Calorimeter Upgrade of the KOTO experiment with both-end readout of CsI crystals with MPPCs
Authors: Nanjo H
Published: June 2020

We are searching for the decay

K
L

→

π
0

ν

ν
¯

in the KOTO experiment at J-PARC. The signal is identified by detecting two photons from the π
0 decay with a calorimeter composed of undoped CsI crystals. The main background “hadron cluster background” is caused by a neutron hitting the calorimeter to form two clusters: a neutron in the beam halo hits the calorimeter to generate the first cluster, and a secondary neutron generated in the interaction creates the second separated cluster. In order to reduce this background, we upgraded the calorimeter to have both-end readout by attaching MPPCs on the upstream face of each CsI crystal in addition to the original PMT attached on the downstream face. The background can be rejected exploiting the timing difference between the MPPC and PMT, since neutrons tend to interact deeper inside the crystals. We installed the MPPCs in 2018, and evaluated the performance with data taken in 2019. The principle in the calorimeter upgrade and the performance of the background reduction are reported.
A future

KL0→π0νν¯

experiment at J-PARC
Authors: Nomura Tadashi
Published: June 2020

A next-generation experiment at J-PARC to measure the branching ratio of

K
L
0

→

π
0

ν

ν
¯

is being considered. The currently-running experiment in the Hadron Experimental Facility of J-PARC, the KOTO experiment, will reach a sensitivity below 10−10 in 3–4 years but would take longer time toward the sensitivity predicted by the Standard Model. It is desirable to have a new experiment that can observe O(100) events and measure the branching ratio of

K
L
0

→

π
0

ν

ν
¯

. Such an experiment, so-called KOTO step-2, has been discussed as a part of the project of the facility extension. A new beam line with a smaller production angle and a larger detector, accommodated in the extended facility, will provide a higher kaon ux and a larger detection acceptance, and thus brings a better sensitivity. In this paper, a baseline design of the KOTO step-2 and its potential sensitivity are discussed.
Feebly-interacting particles: experimental landscape
Authors: Lanfranchi G.
Published: June 2020

Feebly-interacting particles represent an alternative paradigm with respect to the traditional strongly-coupled Beyond the Standard Model physics explored at the LHC and can provide an answer to many fundamental open questions in particle physics. This document presents the state of the art of searches for feebly-interacting particles at accelerator-based experiments including projects proposed at CERN and currently discussed in the European Strategy for Particle Physics update.
Search for invisible dark photon at NA62
Authors: Spadaro T
Published: June 2020

Very weakly coupled new-physics particles in the MeV-GeV range appear as mediators in various “portals” to a hidden sector. Their interaction with Standard Model particles is feeble and these states are usually long-lived, so that the experimental search fully profits of a high-intensity setup, such as that of fixed-target experiments. Within the vector portal hidden-sector model a dark photon might exist which predominantly decays to dark matter particles. A search for such an invisible particle has been performed, exploiting the efficient photon-veto capability and high resolution tracking of the NA62 detector at CERN. The signal stems from the chain K
+ → π
+
π
0 followed by the π
0 decay to a photon-dark-photon pair. No significant statistical excess has been identified. Upper limits on the dark photon coupling to the ordinary photon as a function of the dark photon mass have been set.
Dark Sector Physics with Belle II
Authors: Corona L
Published: June 2020

The Belle II experiment at the SuperKEKB energy-asymmetric e
+
e
− collider is a substantial upgrade of the KEKB facility at the Japanese KEK laboratory. The design luminosity of the machine is 8 · 1035 cm−2s−1 and the Belle II experiment aims to record 50 ab−1 of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, where about 0.5 fb−1 of data have been collected. Regular operation of SuperKEKB has started in March 2019: the machine has achieved a peak luminosity of 1034 cm−2s−1, and Belle II has recorded a data sample of about 6.5 fb−1. Already this early data set with specifically designed triggers offers the possibility to search for a large variety of dark sector particles in the GeV mass range complementary to searches at LHC and dedicated low energy experiments. The Belle II dark matter analyses will benefit from more data in the process of being accumulated. This talk will review the state of the dark sector searches at Belle II with a focus on the discovery potential of the early data, and show the first results.
The Data-Acquisition System with Cluster-Finding Trigger at the J-PARC KOTO Experiment
Authors: Lin C , Hsiung Y B , Wah Y W , Tung Y C , Luo Y T , Bogdan M
Published: June 2020

In order to collect the events efficiently with a high intensity beam, we built a new trigger electronics system based on the calibrated energy information and the number of electromagnetic shower clusters in the calorimeter for the J-PARC KOTO experiment. The dead time of this system is 0.16 µs and the loss was measured to be less than 1%. By performing the online clustering algorithm on the simulated data, the trigger efficiency for the primary mode

K
L

→

π
0

ν

ν
¯

is estimated to be 99.6%.
Construction of the double-side readout calorimeter for

KL→π0νν¯

search
Authors: Kotera K
Published: June 2020

We study the rare decay

K
L

→

π
0

ν

ν
¯

at the KOTO experiment at J-PARC. To detect two photons from the π
0, the KOTO detector consists of a cesium iodide (CsI) calorimeter and hermetical veto counters. The calorimeter is made of 50 cm-long CsI crystals stacked in a cylinder of 1.9 m diameter. Each crystal is read out with a PMT on its rear side. One of the major backgrounds is caused by a neutron generating two clusters in the calorimeter. To reject such events, we have upgraded the calorimeter to distinguish photon clusters from neutron clusters by measuring the time difference of the scintillation light at the front and rear ends of the crystals. We established the methods to install 4080 silicone photomultipliers on the front surface of crystals for this purpose.
Neutron rejection performance of the upgraded KOTO CsI calorimeter
Authors: Osugi M
Published: June 2020

We are searching for the

K
L

→

π
0

ν

ν
¯

decay at the J-PARC KOTO experiment. The signature of the signal events is two photons from a π
0 decay and no other detectable particles. One of the main backgrounds is caused by neutrons in the beam halo. If a beam halo neutron produces a hadronic shower in the calorimeter and a secondary neutron interacts at a different position in the calorimeter, it can mimic the

K
L

→

π
0

ν

ν
¯

decay. To suppress this hadron-cluster background, we installed MPPCs (silicon photo sensor) on the upstream surface of the CsI calorimeter in 2018. Neutrons and photons can be distinguished by using the timing difference between the MPPC signal from upstream and the PMT signal from downstream. The hadron-cluster background is suppressed to a 2.2% level retaining the 90% signal efficiency.
Comparative Analysis of Neutron, Proton, Alpha and Beta Radiation Shielding Parameters of PES and PVDC
Authors: Thakur Sonika , Kaur Parminder
Published: June 2020

In medical applications, where polymers and plastics are used as tissue equivalent and phantom materials, the determination of accurate values of radiation shielding parameters becomes very important. In this context, the present work is aimed at determining the values of radiation shielding parameters of two polymers, viz. polyethersulphone (PES) and polyvinylidenechloride (PVDC) and then doing a comparative analysis of their shielding abilities in order to find a better material for shielding. The neutron shielding parameter was determined and was also compared with some common neutron shielding materials such as Boric Acid, Boron Carbide and Graphite. Furthermore, the shielding against charged particles i.e. neutron, proton and alpha particle was also studied with the help of the parameters, ‘mass stopping power’ and ‘projected range’. It was speculated that PES is superior to PVDC for shielding against neutrons, protons, alpha and beta radiation due to higher content of low atomic number elements per monomer unit. So, PES can be used potentially for radiation shielding in medical field.
Structural and Optical Properties of Sr2Co1.9Bi0.1Fe11.9 Zn0.1O22/PANI Nanocomposites
Authors: Sharma Shaweta , Mohammed J. , Trudel Tchouank Tekou Carol , Getso R.S , Kumar Pushpendra , Basandrai D. , Srivastava A. K.
Published: June 2020

Recently Hexaferrites have attracted the attention of researchers due to its wide applications such as permanent magnets, magnetic recording media, microwave applications and Wireless telecommunication system. Sr2Co1.9Bi0.1Fe11.9 Zn0.1O22 was successfully synthesized using sol-gel method while oxidative polymerization was employed to synthesized polyaniline (PANI). The precursor material is pre sintered at 500°C for 5 hours and sintered at 1000°C for 5 hours. The characteristics of the samples were defined by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and Ultraviolet visible spectrophotometer (UV-vis). XRD analysis confirms the spectral purity of the sample. FTIR analysis indicates the formation of y-type hexaferrites by the appearance of two prominent peaks at 400 and 600 cm−1. Raman spectra show the presence of Y-type hexaferrites and PANI by the appearance of prominent Raman shifts. The band gap of the prepared nanocomposites was evaluated using UV-vis spectroscopy.
Nonlinear Evolution of q-Gaussian Laser Beams in Preformed Parabolic Plasma Channels
Authors: Gupta Naveen , Singh Rajender
Published: June 2020

Theoretical investigation on nonlinear propagation characteristics of q-Gaussian laser beams in preformed parabolic plasma channels has been presented. The optical response of the channel has been modelled by ponderomotive nonlinearity. Following Virial theorem in W.K.B approximation, semi analytical solution of the wave equation for the field of laser beam has been obtained. Particularly the evolutions of beam width and axial phase of the laser beam have been investigated in detail. Self trapping of the laser beam arising as a consequence of the cancellation of diffraction broadening by nonlinear refraction of the laser beam has also been investigated.
Theoretical and experimental ultrasonic velocities Comparison of binary mixtures of triethylene glycols and glycerol at different temperatures
Authors: Chakraborty Nabaparna , Kaur Parminder , Kaur Kirandeep , Juglan Kailash Chandra , Kumar Harsh
Published: June 2020

The densities and sound velocities of binary mixtures of triethylene glycol are measured at different temperatures and at frequency of 2 MHz over entire range of mole fraction. Various theoretical models, such as Nomoto, Impedance, Junjie, Van Dael and Vangeel, have been used to measure theoretical ultrasonic velocities. The average percentage error was estimated and the chi-square fitness test was also used to check the validity of theoretical models. The variance from the experimental results is interpreted in terms of molecular interactions between the components of the binary mixtures.
Study of intermolecular interaction of binary mixture of adrenaline and KOH
Authors: Kaur Parminder , Chakraborty Nabaparna , Singh Satnam , Juglan K.C. , Kumar Harsh
Published: June 2020

The Density and Ultrasonic Velocity of Adrenaline with KOH have been measured at different range of temperatures for different concentrations. Ultrasonic velocity and density values increases with increase in concentration. By using ultrasonic and volumetric data various parameters such as adiabatic compressibility, acoustic impedance, available volume, molar volume, intermolecular free length, Rao’s constant, Wada’s constant, Van Der Waal Constant, relative intensity and effective molecular weight have been calculated. With rise in temperature the interaction between the solute and solvent particles increases, which is confirmed by available volume and intermolecular free length. The non-linear variations in Rao’s constant, Wada’s constant, Van Der Waal Constant and other parameters suggest the presence of complex formation or charge transfer interaction or dipole-dipole interaction or dispersive forces or maybe all in the solution.
Optimization of electrical and optical properties of tin sulfide for thin film photovoltaics using SCAPS
Authors: Kancharla Srikanth , Kaushik Deepak Kumar
Published: June 2020

Tin sulfide (SnS), being a binary metal chalcogenide, can be a potential absorber material for the thin film photovoltaics because of its optimum direct bandgap (1.3 eV) and high absorption coefficient (>104 cm−1). In the present work, the electrical and optical properties of SnS thin film solar cells have been optimized and analyzed by Solar Cell Capacitance Simulator (SCAPS). The effect of thickness and optical band gap of SnS absorber layer on the J-V curve have been investigated to obtain better device performance. The maximum photovoltaic (PV) efficiency achieved by the PV device is 22.3 % with VOC = 756 mV, JSC = 34.9 mAcm−2 and FF = 84.4 %. The VOC value is higher than the reported values for kesterite CZTSSe absorber based solar cells. Consequently, the SnS can be a potential contender for the contemporary thin film solar cells.
Groundwater Contamination By E-Waste And Its Remedial Measure - A Literature Review
Authors: Gupta N. , Nath M.
Published: June 2020

The very precious resource of Earth, the groundwater is being contaminated and polluted day by day. E-Waste is one of the major cause for this problem related to ground water. E-wastes are produced mainly due to discarded electronic gadgets like PCs, tablets, hard drives, printers, monitors, batteries, mobile phones, television, etc. The use of these electronic gadgets is increasing enormously day by day around the globe. Lack of awareness about the proper disposal of these e-wastes cause serious health and environmental issue in developing countries like India and to some extent in developed countries. Discarded computers, mobile phones and other electronic equipment that are considered as e –waste contain hazardous toxic metals like chromium, lead, mercury, iron, zinc, copper, cadmium etc. These e –wastes are dumped in the landfills near the industries where large area of land is available. As most of the industries are located near the water sources, the toxic e-wastes are percolated inside the water hence make the water contaminated inside the deep aquifers. This water is not safe for drinking and other purposes. The quantity of pollutants is more near to the landfill sites and reduces as the distance between the landfill site and aquifer increases. In the present work, a literature survey of groundwater pollution by e-waste and its remedial measure to reduce groundwater contamination is being done.
Near Infrared Spectroscopy as an efficient tool for the Qualitative and Quantitative Determination of Sugar Adulteration in Milk
Authors: Kamboj Uma , Kaushal Neha , Jabeen Shakira
Published: June 2020

The present work focuses on detecting the presence of sugar as an adulterant in milk using Near Infrared Spectroscopy. A chemometric model was formulated to evaluate the presence of sugar content in milk, qualitatively as well as quantitatively using multivariate analysis. Total 24 samples were prepared using three different varieties of milk, out of which three samples were pure and the rest were having sugar present in them. Those 21 milk samples were adulterated with sugar at seven different levels: 0.2%, 0.4%, 0.6%, 0.8%, 1.6%, 3.2%, 0.8% and 6.4% of sugar respectively for each kind of milk. The data collected from NIRS instrument was analyzed using chemometric software (CAMO Unscrambler version X 10.3). The Principal Component Analysis was run on the sample set to know the relation between the different samples on the basis of the Near Infrared spectral data. It was observed that the PCA score plot could classify the samples in three different groups on the basis of their adulteration: low, medium and high adulteration. Partial least square (PLS) regression analysis was used to develop a statistical model to predict the percentage of sugar in the adulterated milk samples by selecting vital wavelengths. It was noticed that the regression model revealed quite good results for the prediction of sugar adulterated milk samples with the coefficient of correlation higher than 0.9 and the root means square error of validation (RMSEV) was 0.04. Thus, it was concluded that NIR spectroscopy could provide dairy industry a simple, efficient, quick, green and non-destructive technique for detection and quantification of milk adulteration.
Study of various relaxation processes and breakdown of Stokes-Einstein Debye relation in supercooled D-xylose
Authors: Acharya Aman Deep , Sharma Sakshi , Ginni  , Bisoyi Sagar , Ahmad Muneer , Singh Lokendra P , Manhas Sandeep S
Published: June 2020

Various relaxation procedure in the supercooled state of D-xylose have been investigated using dielectric spectroscopy over a wide frequency (1 mHz – 10 MHz) and temperature range (140-350 K). The main relaxation process (α) that is accountable for the glass transition phenomena, another secondary relaxation process is also visible below glass transition temperature. The attached hydroxymethyl (-CH2OH) side group to the sugar ring might be responsible for this process. In addition, we have applied Coupling model to find the location of intermolecular relaxation below the glass transition temperature (Tg). The dependence of various dielectric parameters viz. τα, τβ, τγ and τβ cm on temperature have been critically examined. The current experimental result shows that, log10 σdc vs. log10 τα dependence is nonlinear and hence can be described with the fractional Stokes-Einstein-Debye relation.
Structural and Dielectric Properties of Cr3+-Cu2+ Substituted Cobalt Ferrites
Authors: Getso R. S , Mohammed J. , Tchouank Tekou Carol T , Mukhtar G. , Halilu N. , Sharma Shaweta , Srivastava A. K. , Prasad N. , Ahmad M. , Basandrai Deepak
Published: June 2020

The current paper examined the impact of Cu2+-Cr3+ substitution on the structural and dielectric possessions of nanoparticles of cobalt ferrites with the composition Co1-xCuxFe2-xCrxO4 (x=0.0, 0.1, 0.2), synthesized via sol-gel auto-combustion technique and calcinated for 4 hours at 700°C. The XRD patterns display large peaks suggesting nanocrystalline for inverse spinel ferrite formation. FTIR indicate the formation of spinel ferrites by revealing the presence of a typical absorption band in range 390-410 cm−1 and 540-560 cm−1, respectively. FESEM reveals that the specimen is plate and sponge-like structure. In the frequency assortment 1 KHz -5 MHz, dielectric analysis at room temperature was performed and described on the foundation of the phenomenological theory of Koop and the theory of Maxwell Wagner. The result shows the highest dielectric constant without doping is 128.5. The experiment showed low dielectric loss i.e. 1.8 with x=0.2.
Analysis of the Current-Voltage Hysteresis Behavior of Polyvinyl Alcohol-Zinc selenide Nanocomposite Film
Authors: Sinha Subhojyoti , Meikap Ajit Kumar
Published: June 2020

The temperature dependent current-voltage characteristics of the Polyvinyl Alcohol-Zinc selenide nanocomposite films were studied in the voltage window of -5V to +5V. It was observed that with the increase in applied voltage and temperature, the current-voltage characteristics shift from ohmic to non-ohmic nature and show hysteresis behavior. It has also been observed that the sample resistance changes from low resistance state (LRS) to high resistance state (HRS) depending on the applied voltage and temperature. The observed phenomenon has been analyzed based on the available theoretical models to elucidate the prevailing current conduction mechanism.