Astrophysics and Astronomy Commons^™

A Comparative L-Dwarf Sample Exploring The Interplay Between Atmospheric Assumptions And Data Properties, Eileen C. Gonzales, Ben Burningham, Jacqueline K. Faherty, Nikole K. Lewis, Channon Visscher, Mark Marley

Faculty Work Comprehensive List

Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of five L dwarfs of similar effective temperature (Teff) or spectral type to compare their pressure–temperature (P-T) profiles. Additionally, we explore the impact of an object's metallicity and the signal-to-noise ratio (S/N) of the observations on the parameters we can retrieve. We present the first atmospheric retrievals: 2MASS J15261405+2043414, 2MASS J05395200−0059019, 2MASS J15394189−0520428, and GD 165B increasing the small but growing number of L dwarfs retrieved. When compared to the atmospheric retrievals …

Detectability Of Wormholes Through Various Methods, Jonathan W. Keathley

PANDION: The Osprey Journal of Research and Ideas

There are three methods that can possibly detect wormholes: Negative Temperature, Hawking/ Phantom Radiation, and Kα iron emission lines. This paper discusses whether or not any of these three methods are useful ways to detect wormholes with today’s technology and if so, which one is the best and which is the worst. As it turns out, all of these methods have their flaws and impracticalities. After looking through all the evidence and comparing it to what capabilities we have currently, there is clearly a best and worst method. The best method to detect possible wormhole candidates is through the detection …

2022 Scas Annual Meeting Program And Bulletin

Journal of the South Carolina Academy of Science

No abstract provided.

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

Separation Of Track- And Shower-Like Energy Deposits In Protodune-Sp Using A Convolutional Neural Network, A. Abed Abud, B. Abi, R, Acciarri, M. A. Acero, M. R. Adames, G. Adamov, M. Adamowski, D. Adams, M. Adinolfi, A. Aduszkiewicz, M. Andreotti, M. Andrews, F. Andrianala, S. Andringa, N. Anfimov, A. Ankowski, M. Antoniassi, M. Antonova, A. Antoshkin, S. Antusch, Roberto Petti, Et. Al.

Faculty Publications

Liquid argon time projection chamber detector technology provides high spatial and calorimetric resolutions on the charged particles traversing liquid argon. As a result, the technology has been used in a number of recent neutrino experiments, and is the technology of choice for the Deep Underground Neutrino Experiment (DUNE). In order to perform high precision measurements of neutrinos in the detector, final state particles need to be effectively identified, and their energy accurately reconstructed. This article proposes an algorithm based on a convolutional neural network to perform the classification of energy deposits and reconstructed particles as track-like or arising from electromagetic …

Tau Neutrinos In The Next Decade: From Gev To Eev, Roshan Mammen Abraham, Jamie Alvarez-Muñiz, Carlos A. Argüelles, Akitaka Ariga, Tomoko Ariga, Adam Aurisano, Dario Autiero, Mary Bishai, Nilay Bostan, Mauricio Bustamante, Austin Cummings, Valentin Decoene, André De Gouvêa, Giovanni De Lellis, Albert De Roeck, Peter B. Denton, Antonia Di Crescenzo, Milind V. Diwan, Yasaman Farzan, Anatoli Fedynitch, Jonathan L. Feng, Laura J. Fields, Alfonso Garcia, Maria Vittoria Garzelli, Julia Gehrlein, Christian Glaser, Katarzyna Grzelak, Steffen Hallmann, Jeremy Hewes, D Indumathi, Ahmed Ismail, Sudip Jana, Yu Seon Jeong, Kevin J. Kelly, Spencer R. Klein, Felix Kling, Thomas Kosc, Umut Kose, D Jason Koskinen, John Krizmanic, Jeff Lazar, Yichen Li, Ivan Martinez-Soler, Irina Mocioiu, Jiwoo Nam, Valentin Niess, Nepomuk Otte, Sameer Patel, Roberto Petti, Et. Al.

Faculty Publications

Tau neutrinos are the least studied particle in the standard model. This whitepaper discusses the current and expected upcoming status of tau neutrino physics with attention to the broad experimental and theoretical landscape spanning long-baseline, beam-dump, collider, and astrophysical experiments. This whitepaper was prepared as a part of the NuTau2021 Workshop.

Eclipse Of The V773 Tau B Circumbinary Disc, M. A. Kenworthy, D. González Picos, E. Elizondo, R. G. Martin, D. M. Van Dam, J. E. Rodriguez, G. M. Kennedy, C. Ginski, M. Mugrauer, N. Vogt, C. Adam, R. J. Oelkers

Physics & Astronomy Faculty Research

Context. Young multiple stellar systems can host both circumstellar and circumbinary discs composed of gas and dust, and the orientations of circumbinary discs can be sculpted by the orientation and eccentricity of the central binaries. Studying multiple binary systems and their associated discs enables our understanding of the size and distribution of the planetary systems that subsequently form around them.

Aims. A deep (~70%) and extended (~150 days) eclipse was seen towards the young multiple stellar system V773 Tau in 2010. We interpret it as being due to the passage of a circumbinary disc around the B components moving in …

Latest Results From The Cuore Experiment, I. Nutini, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone Iii, O. Azzolini, G. Bari, F. Bellini, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, Carl Rosenfeld Jr., Carl Rosenfeld, Et. Al.

Faculty Publications

The Cryogenic Underground Observatory for Rare Events (CUORE) is the frst cryogenic experiment searching for 0vββ decay that has been able to reach the onetonne mass scale. The detector, located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, consists of an array of 988 TeO₂ crystals arranged in a compact cylindrical structure of 19 towers. CUORE began its frst physics data run in 2017 at a base temperature of about 10 mK and in April 2021 released its 3rd result of the search for 0vββ, corresponding to a tonne-year of TeO₂ exposure. This is the …

Extended Duration Studies Of Energetic Particles In The Stratosphere, Ian Kuhl, Ashna Coondiah, Howard L. Brooks

Annual Student Research Poster Session

The Balloon Assisted Stratospheric Experiments (BASE) program aims to measure atmospheric muon concentration at the Pfotzer Maximum with Geiger Counters carried by weather balloons. The most intense radiation is found at the Pfotzer Maximum 18 - 22 km (11 - 13 mi) above ground level. During this summer, seven flights were conducted to attain maximum time in the Pfotzer Maximum using different strategies like underfilling and multiple balloon systems.

Galaxy And Mass Assembly (Gama): Probing Galaxy-Group Correlations In Redshift Space With The Halo Streaming Model, Qianjun Hang, John A. Peacock, Shadab Alam, Yan-Chuan Cai, Katarina Kraljic, Marcel Van Daalen, M Bilicki, Benne Holwerda, J Loveday

Faculty and Staff Scholarship

We have studied the galaxy-group cross-correlations in redshift space for the Galaxy And Mass Assembly (GAMA) Survey. We use a set of mock GAMA galaxy and group catalogues to develop and test a novel ‘halo streaming’ model for redshift-space distortions. This treats 2-halo correlations via the streaming model, plus an empirical 1-halo term derived from the mocks, allowing accurate modelling into the non-linear regime. In order to probe the robustness of the growth rate inferred from redshift-space distortions, we divide galaxies by colour, and divide groups according to their total stellar mass, calibrated to total mass via gravitational lensing. We …

Dominant Frequency Extraction For Operational Underwater Sound Of Offshore Wind Turbines Using Adaptive Stochastic Resonance, Rongxin Wang, Xiaomei Xu, Zheguang Zou, Longfei Huang, Yi Tao

Faculty and Student Publications

Underwater sound generated by the rapidly increasing offshore wind farms worldwide greatly affects the underwater soundscape and may cause long-term cumulative effects on sound-sensitive marine organisms. However, its analysis and impact assessment are heavily interfered with by underwater ambient noise. In this study, an adaptive stochastic resonance method is proposed to extract the dominant frequency of wind turbine operational sound when heavy noise is present. In particular, a time–frequency–amplitude fusion index was proposed to guide the parameter tuning of an adaptive stochastic resonance system, and an equilibrium optimizer based on the physical dynamic source–sink principle was adopted to optimize the …

Phys 927

Department of Physics and Astronomy: Syllabi

No abstract provided.

The Physical Properties Of Low-Redshift Felobal Quasars. I. Spectral-Synthesis Analysis Of The Broad Absorption-Line (Bal) Outflows Using Simbal, Hyunseop Choi, Karen M. Leighly, Donald M. Terndrup, Collin Dabbieri, Sarah C. Gallagher, Gordon T. Richards

Physics and Astronomy Publications

We present the first systematic study of 50 low-redshift (0.66 < z < 1.63) iron low-ionization broad absorption-line quasars (FeLoBALQs) using SimBAL, which represents a more than five-fold increase in the number of FeLoBALQs with detailed absorption line spectral analyses. We found the outflows have a wide range of ionization parameters, − 4 ≲ log U ≲ 1.2 and densities, 2.8 ≲ log n ≲ 8 [ cm − 3 ] . The objects in our sample showed FeLoBAL gas located at a wide range of distances 0 ≲ log R ≲ 4.4 [pc], although we do not find any evidence for disk winds (with R ≪ 0.01 pc) in our sample. The outflow strength primarily depends on the outflow velocity with faster outflows found in quasars that are luminous or that have flat or redder spectral energy distributions. We found that ∼18% of the FeLoBALQs in the sample have the significantly powerful outflows needed for quasar feedback. Eight objects showed overlapping troughs in the spectra, and we identified eleven loitering outflow objects, a new class of FeLoBALQs that are characterized by low outflow velocities and high column density winds located log R ≲ 1 [pc] from the central engine. The FeLoBALs in loitering outflows objects do not show properties expected for radiatively driven winds, and these objects may represent a distinct population among FeLoBALQs. We discuss how the potential acceleration mechanisms and the origins of the FeLoBAL winds may differ for outflows at different locations in quasars.

Toi-1468: A System Of Two Transiting Planets, A Super-Earth And A Mini-Neptune, On Opposite Sides Of The Radius Valley, P. Chaturvedi, P. Bluhm, E. Nagel, A. P. Hatzes, G. Morello, M. Brady, J. Korth, K. Molaverdikhani, D. Kossakowski, J. A. Caballero, E. W. Guenther, E. Pallé, N. Espinoza, A. Seifahrt, N. Lodieu, C. Cifuentes, E. Furlan, P. J. Amado, T. Barclay, J. Bean, V. J. S. Béjar, G. Bergond, A. W. Boyle, D. Ciardi, K. A. Collins, K. I. Collins, E. Esparza-Borges, A. Fukui, C. L. Gnilka, R. Goeke, P. Guerra, T. Henning, E. Herrero, S. B. Howell, S. V. Jeffers, J. M. Jenkins, Eric L.N. Jensen, D. Kasper, T. Kodama, D. W. Latham, M. J. López-González, R. Luque, D. Montes, J. C. Morales, M. Mori, F. Murgas, N. Narita, G. Nowak, H. Parviainen, V. M. Passegger, A. Quirrenbach, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, E. Rodriguez, C. Rodríguez-López, M. Schlecker, R. P. Schwarz, A. Schweitzer, S. Seager, G. Stefánsson, C. Stockdale, L. Tal-Or, J. D. Twicken, S. Vanaverbeke, G. Wang, D. Watanabe, J. N. Winn, M. Zechmeister

Physics & Astronomy Faculty Works

We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b (P_b = 1.88 d), has a planetary mass of M_b = 3.21 ± 0.24 M_⊕ and a radius of …

Dynamics Of Atmospheric Gravity Wave Breaking In The Mesopause Region, Fan Yang

Doctoral Dissertations and Master's Theses

GWs significantly impact the Mesosphere and Lower Thermosphere (MLT), and as a consequence of GW breaking, atmospheric turbulence plays an essential role in the mixing and transport of momentum, mass, and chemical materials in MLT. The main focus of this research for the fulfillment of the proposed Ph.D. dissertation is to improve the understanding of the dynamic process of wave breaking and their effects in the mesopause region above Andes Lidar Observatory (30.2◦ S, 70.7◦ W). A few scientific topics related to GW break- ing are addressed. What are the probabilities of the atmosphere becoming convectively or dynamically unstable in …

Diffraction-Free Beam Propagation At The Exceptional Point Of Non-Hermitian Glauber Fock Lattices, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We construct localized beams in a non-Hermitian Glauber Fock (NGF) lattice of coupled waveguides and show that they can propagate for a long distance without almost no diffraction. We specifically obtain the diffraction-free beams in a finite NGF lattice at the exceptional point (EP) by using the exact eigenstates of the semi-infinite unidirectional NGF lattice. We provide a numerical approach to finding other lattices that are capable of supporting non-diffracting beams at EPs.

Saturable Absorption Of Free-Electron Laser Radiation By Graphite Near The Carbon K-Edge, Lars Hoffman, Sasawat Jamnuch, Craig Schwartz, Tobias Helk, Sumana L. Raj, Hikaru Mizuno, Riccardo Mincigrucci, Laura Foglia, Emiliano Principi, Richard J. Saykally, Walkter S. Drisdell

Nevada Extreme Conditions Laboratory Faculty Research

The interaction of intense light with matter gives rise to competing nonlinear responses that can dynamically change material properties. Prominent examples are saturable absorption (SA) and two-photon absorption (TPA), which dynamically increase and decrease the transmission of a sample depending on pulse intensity, respectively. The availability of intense soft X-ray pulses from free-electron lasers (FELs) has led to observations of SA and TPA in separate experiments, leaving open questions about the possible interplay between and relative strength of the two phenomena. Here, we systematically study both phenomena in one experiment by exposing graphite films to soft X-ray FEL pulses of …

A Wind Environment And Lorentz Factors Of Tens Explain Gamma-Ray Bursts X-Ray Plateau, Hüsne Dereli-Bégué, Asaf Pe’Er, Felix Ryde, Samantha R. Oates, Bing Zhang, Maria G. Dainotti

Physics & Astronomy Faculty Research

Gamma-ray bursts (GRBs) are known to have the most relativistic jets, with initial Lorentz factors in the order of a few hundreds. Many GRBs display an early X-ray light-curve plateau, which was not theoretically expected and therefore puzzled the community for many years. Here, we show that this observed signal is naturally obtained within the classical GRB fireball model, provided that the initial Lorentz factor is rather a few tens, and the expansion occurs into a medium-low density wind. The range of Lorentz factors in GRB jets is thus much wider than previously thought and bridges an observational gap between …

On A Novel Approach To The Thermogravimetric Analysis Of Polymers: Polystyrene, Mircea Chipara, Karen Lozano, Dorina M. Chipara, Carlos Delgado, Victoria Padilla

Physics & Astronomy Faculty Publications

A novel equation that describes the temperature dependence of the residual mass fraction (as determined by thermogravimetric analysis) is derived, assuming that the dependence of the residual mass fraction on temperature has a sigmoidal shape. The equation allows the estimation of the sigmoidal activation energy solely from the experimental data at a single heating rate. The consistency with the isoconversional approach and the relationship between the Ozawa and sigmoidal activation energies are reported. The equation was successfully tested by the thermal degradation of atactic polystyrene at various heating rates. Both the thermograms and their derivatives are analyzed in detail.

Losing The Dark: How Light Pollution Impacts Humans And The Environment, And What We Can Do To Win Back The Night, Marc Gagné

Sustainability Research & Practice Seminar Presentations

Professor Marc Gagne, Earth and Space Sciences - Losing the Dark: How light pollution impacts humans and the environment, and what we can do to win back the night

Incorporating Baryon-Driven Contraction Of Dark Matter Halos In Rotation Curve Fits, Pengfei Li, Stacy S. Mcgaugh

Faculty Scholarship

The condensation of baryons within a dark matter (DM) halo during galaxy formation should result in some contraction of the halo as the combined system settles into equilibrium. We quantify this effect on the cuspy primordial halos predicted by DM-only simulations for the baryon distributions observed in the galaxies of the SPARC database. We find that the DM halos of high surface brightness galaxies (with Σeff 3; 100L pc-2 at 3.6 μm) experience strong contraction. Halos become more cuspy as a result of compression: the inner DM density slope increases with the baryonic surface mass density. We iteratively fit rotation …

Distributions Of Gas And Small And Large Grains In The Lkh 330 Disk Trace A Young Planetary System, Paola Pinilla, Myriam Benisty, Nicolás T. Kurtovic, Jaehan Bae, Ruobing Dong, Zhaohuan Zhu, S. Andrews, J. Carpenter, C. Ginski, J. Huang, A. Isella, L. Perez, L. Ricci, G. Rosotti, M. Villenave, D. Wilner

Physics & Astronomy Faculty Research

Planets that are forming around young stars are expected to leave clear imprints in the distribution of the gas and dust of their parental protoplanetary disks. In this paper, we present new scattered light and millimeter observations of the protoplanetary disk around LkH 330, using SPHERE/VLT and ALMA, respectively. The scattered-light SPHERE observations reveal an asymmetric ring at around 45au from the star in addition to two spiral arms with similar radial launching points at around 90au. The millimeter observations from ALMA (resolution of 006 004 ) mainly show an asymmetric ring located at 110au from the star. In addition …

Search For Gravitational Waves From Scorpius X-1 With A Hidden Markov Model In O3 Ligo Data, R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari, Michael G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Results are presented for a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to allow for spin wandering. This search improves on previous HMM-based searches of Laser Interferometer Gravitational-Wave Observatory data by including the orbital period in the search template grid, and by analyzing data from the latest (third) observing run. In the frequency range searched, from 60 to 500 Hz, we find no evidence of gravitational radiation. This is the most sensitive search for Scorpius X-1 using a HMM to date. For the most sensitive subband, starting at …

Improving The Conductivity Of Graphite-Based Films By Rapid Laser Annealing, Gulsum Ersu, Sruthi Kuriakose, Stuart J. Goldie, Abdullah M. Al-Enizi, Ayman Nafady, Carmen Munuera, Claudia Backes, Joshua O. Island, Andres Castellanos-Gomez

Physics & Astronomy Faculty Research

We present a method to anneal devices based on graphite films on paper and polycarbonate substrates. The devices are created using four different methods: spray-on films, graphite pencil-drawn films, liquid-phase exfoliated graphite films, and graphite powder abrasion-applied films. We characterize the optical properties of the films before and after laser annealing and report the two-terminal resistance of the devices for increased laser power density. We find the greatest improvement (16× reduction) in the resistance of spray-on film devices starting from 25.0 kΩ and reaching 1.6 kΩ at the highest annealing power densities. These improvements are attributed to local laser ablation …

The Roles Of Flux Tube Entropy And Effective Gravity In The Inward Plasma Transport At Saturn, S. Wing, M. F. Thomsen, J. R. Johnson, D. G. Mitchell, R. C. Allen, X. Ma, P. A. Delamere

Faculty Publications

The inward plasma transport at the Saturnian magnetosphere is examined using the flux tube interchange stability formalism developed by Southwood & Kivelson. Seven events are selected. Three cases are considered: (1) the injected flux tube and ambient plasmas are nonisotropic, (2) the injected flux tube and ambient plasmas are isotropic, and (3) the injected flux tube plasma is isotropic, but the ambient plasma is nonisotropic. Case 1 may be relevant for fresh injections, while case 3 may be relevant for old injections. For cases 1 and 2, all but one event have negative stability conditions, suggesting that the flux tube …

Kinetic Modeling Of Ionospheric Outflows Observed By The Visions-1 Sounding Rocket, Robert M. Albarran Ii

Doctoral Dissertations and Master's Theses

Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of nightside ion outflow at altitudes where it is initiated, below 1000 km. Energetic ion data from the VISIONS-1 polar cap boundary crossing …

Clustering Behavior In Solar Flare Dynamics, Elmer C. Rivera, Jay R. Johnson, Jonathan Homan, Simon Wing

Faculty Publications

The solar magnetic activity cycle provides energy input that is released in intense bursts of radiation known as solar flares. As such, the dynamics of the activity cycle is embedded in the sequence of times between the flare events. Recent analysis shows that solar flares exhibit memory on different timescales. These previous studies showed that the time ordering of flare events is not random, but rather there is dependence between successive flares. In the present work, the clustering of flares is demonstrated through a straightforward nonparametric method where the cumulative distribution function of successive flares is compared with the cumulative …

Dirac Dark Matter, Neutrino Masses, And Dark Baryogenesis, Diego Restrepo, Andrès Rivera, Walter Tangarife

Physics: Faculty Publications and Other Works

We present a gauged baryon number model as an example of models where all new fermions required to cancel out the anomalies help to solve phenomenological problems of the standard model (SM). Dark fermion doublets, along with the isosinglet charged fermions, in conjunction with a set of SM-singlet fermions, participate in the generation of small neutrino masses through the Dirac-dark Zee mechanism. The other SM-singlets explain the dark matter in the Universe, while their coupling to an inert singlet scalar is the source of the CP violation. In the presence of a strong first-order electroweak phase transition, this “dark” CP …

Coupled Surface Plasmon–Phonon Polariton Nanocavity Arrays For Enhanced Mid-Infrared Absorption, Satya R. Kachiraju, Ivan Nekrashevich, Imtiaz Ahmad, Hira Farooq, Long Chang, Sangsik Kim, Myoung-Hwan Kim

Physics & Astronomy Faculty Publications

Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micronthick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈��0/150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10–12 microns) via excitation of coupled surface plasmon–phonon polaritons. The proposed metal–insulator–polar dielectric (gold–silicon–silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wave

India’S First Robotic Eye For Time-Domain Astrophysics: The Growth-India Telescope, Harsh Kumar, Varun Bhalerao, G. C. Anupama, Sudhanshu Barway, Judhajeet Basu, Kunal Deshmukh, Kishalay De, Anirban Dutta, Christoffer Fremling, Hrishikesh Iyer, Adeem Jassani, Simran Joharle, Viraj Karambelkar, Maitreya Khandagale, K. Adithya Krishna, Sumeet Kulkarni, Sujay Mate, Atharva Patil, D. V. S. Phanindra

Faculty and Student Publications

We present the design and performance of the GROWTH-India telescope, a 0.7 m robotic telescope dedicated to time-domain astronomy. The telescope is equipped with a 4k back-illuminated camera that gives a 0.°82 field of view and a sensitivity of m g′ ∼ 20.5 in 5 minute exposures. Custom software handles observatory operations: attaining high on-sky observing efficiencies (≳80%) and allowing rapid response to targets of opportunity. The data processing pipelines are capable of performing point-spread function photometry as well as image subtraction for transient searches. We also present an overview of the GROWTH-India telescope’s contributions to the studies of gamma-ray …