BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:The back – gated AlGaN/GaN HEMT structure for observation of twi sted plasmonic states in terahertz frequency range. DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-812@events.ncbj.gov.pl DESCRIPTION:Speakers: Piotr Dróżdż (CENTERA Laboratories\, Institute of High Pressure Physics\, PAS)\nThe Inverse Faraday Effect (IFE) is the app earance of stationary magnetic moments magnetization caused by circulary p olarized ligh. Up to this moment\, IFE has been mostly studied in the magn etic materials. In recent years\, the IFE was predicted in the periodic la ttice of metallic disks or spheres placed in the vicinity of two-dimension al electron liquid and under illumination of the external circularly polar ized light. The radiation causes the DC current loops in the electron liqu id\, thus leading to appearance of static magnetic moments. As a result\, the interaction between metal disks and two-dimensional electron liquid\, the "twisted" plasmonic modes are excited what leads to the appearance of DC circulating current due to rectification. In this work\, we present the basic idea of IFE. The mechanism of the effect is described and the theor etical predictions are presented. We propose GaN/AlGaN as a basic system f or the experimental realization of the IFE. We present GaN/AlGaN HEMT like structure with 2-dimensional electron gas as a channel\, that was made in order to observe the twisted plasmonic modes experimentally. On top of th e structure\, the periodic lattice of metal disks was fabricated with use of electron beam lithography. We present the theoretical predictions and t he technological realization of the structure as well as its basic charact erization. The frequency of the twisted plasmonic modes is expected to be in range of 0.6 - 1.2 THz thus leading to potential applications in terahe rtz physics and technology.\n\nhttps://events.ncbj.gov.pl/event/75/contrib utions/812/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/812/ END:VEVENT BEGIN:VEVENT SUMMARY:A simple method of evaluating dielectric properties of dielectric layers at sub-terahertz frequencies using tapered dielectric waveguides DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-811@events.ncbj.gov.pl DESCRIPTION:Speakers: Valeri Mikhnev (CENTERA Laboratories\, Institute of High Pressure Physics PAS)\nThe accurate knowledge of constitutive paramet ers of dielectric materials is demanded in numerous applications\, from de signing quasi-optical components\, antennas and sensors to nondestructive testing. Terahertz time-domain spectroscopy (THz-TDS) is a recognized tech nique of the broadband material characterization\, but it requires a well- adjusted measurement setup\, special sample holders etc. Alternatively\, t he dielectric properties of materials can be evaluated using such widely u sed sub-THz apparatus as a vector network analyzer with frequency extender s. To this end\, they must be additionally equipped with the dielectric me asurement cells and corresponding software while the free-space measuremen ts require a careful preparatory work similar to THz-TDS systems.\nWe prop ose a simple transmission-mode method of evaluating dielectric properties of thin-sheet materials utilizing a pair of metal-to dielectric waveguide transitions connected to the sub-THz frequency extenders. The dielectric s ample under test is placed in the gap between two open-ended tapered diele ctric waveguides (DW). The dimensions of DW\, length and shape of the tape r have been chosen to ensure the best operation in the near field. The mai n advantage of the tapered DW is an extremely low reflection from the tape r both for outcoming and incident waves that makes the parasitic interfere nce in the measurement area negligible. This allows to use simple formulas for extracting the constitutive parameters of dielectrics. Due to small d imensions of DW\, the illuminated spot of the sample is even smaller than in a free-space setup with focusing lenses.\nThe method was tested using t he frequency extenders V15VNA2-T/R (frequency range up to 75 GHz) and samp les of Teflon\, high-density polyethylene\, high-frequency laminate RT/dur oid 5870\, alumina with the dielectric constant in the range 2.08 to 9.8 a nd thickness of 0.8 mm to 2.4 mm. The measurement error in all cases was a bout 1-3%.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/811/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/811/ END:VEVENT BEGIN:VEVENT SUMMARY:Graphene/hBN - based varactor for novel sub-THz phase shifter. DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-807@events.ncbj.gov.pl DESCRIPTION:Speakers: Piotr Dróżdż (CENTERA Laboratories\, Institute of High Pressure Physics\, PAS)\nThe mm-wave and terahertz (THz) frequency r anges are gaining much attention recently due to their high applicability\ , which creates a need for the development of the devices operating in abo vementioned frequency ranges. One among the most important elements of suc h THz devices (e. g. Phase shifters) are varactors (variable capacitors)\, that allow tuning of the system via electrically-induced capacitance shif t. In [1]\, the carbon nanotubes (CNTs) MicroElectroMechanical System (MEM S) varactor is described. \n\nThe device consists of series of etched tre nches with metallized bottoms structuring the bottom electrode. On top of the trenches\, the layer of CNTs is placed\, serving as a top electrode. W hen voltage is applied between the top/bottom electrodes\, the electricall y-formed force causes the nanotube layer to bend towards the bottom electr ode resulting in distance reduction that in final increases the capacitanc e. \n\nHowever\, CNTs are known from changing the capacity by themselves w hen exposed to various environmental conditions like temperature variation \, humidity or illumination. \n\nHere\, we present the new type of the va ractor fabricated upon silicon/SixNy platform with use of carbon-based met amaterials. The design of the structure is inspired by the one reported in [1]. However\, in our approach\, graphene (GR) is used as a top electrode \, since it seems to be more stable and immune against external environmen t conditions. Futher stability improvement is achieved by covering GR with PMMA protective layer. To avoid shorting between GR and bottom electrode an hBN insulating layer was placed under GR. \n\nWe present the character isation measurements of the metamaterial layers used in our device. Finall y\, the electrical characterisation of working device is presented includi ng I - V and C - V characteristics\, which appear to be linear. The tunabi lity of our devices seems to be of the order of few hundred pF/V. \n\n[1] A. A. Generalov et al.\, Nanotechnology 26\, 045201 (2015).\n\nhttps://eve nts.ncbj.gov.pl/event/75/contributions/807/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/807/ END:VEVENT BEGIN:VEVENT SUMMARY:FinFET and EdgeFET for THz detectors DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-801@events.ncbj.gov.pl DESCRIPTION:Speakers: Grzegorz Cywiński (CENTERA Labs\, Institute of Hig h Pressure Physics PAS )\, Pavlo Sai (CENTERA Labs\, Institute of High Pr essure Physics PAS )\nWe report on the investigations of FinFET and EdeFET AlGaN/GaN field effect transistors as THz detectors. Both devices we fabr icated in the same technological runs on the base of the two-dimensional e lectron gas (2DEG) AlGaN/GaN epitaxial structures and then investigated to wards THz detection. Design of a new FET dubbed EdgeFET is based on two la teral Schottky barrier gates on the sides of 2DEG channel\, which is the s ignificant difference to FinFET. This side gate configuration allowed us t o electrically control the conductivity of the channel by changing its wid th while keeping the carrier density and mobility virtually unchanged. Ele ctrical parameters and photoresponse of EdgeFET will be discussed and comp ared to the standard FinFET device. For understanding the transistor pinch -off process of the EdgeFET channel\, we proposed a gradual channel model. Contrary to FinFET this kind of EdgeFET allowed us to efficiently control the current flow in the 2DEG conduction channel. Moreover\, due to deplet ion\, regions at a certain range of reverse biasing form a nanowire\, whic h is beneficial for the adjustable resonant THz detection. Our studies of DC characteristics and photoresponse in the sub-terahertz frequency confir m the validity of the approach.\n\nhttps://events.ncbj.gov.pl/event/75/con tributions/801/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/801/ END:VEVENT BEGIN:VEVENT SUMMARY:Technology of graphene and related nanomaterials for THz applicati on DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-795@events.ncbj.gov.pl DESCRIPTION:Speakers: Aleksandra Krajewska (CENTERA Laboratories\, Institu te of High Pressure Physics PAS\, Warsaw\, Poland)\nTerahertz (THz) system s and technology have become of large interest over the last 20 years. How ever\, it still needs new and innovative solutions in the field of both ge neration and detection of THz radiation. Despite the fact that scientists in many research centers are constantly working on the production of new T Hz sources and detectors based on semiconductors such as silicon\, it turn out that carbon nanomaterials\, including graphene and van der Waals hete rostructures consisting of layered two-dimensional (2D) materials (h-BN or MoS2) are extremely promising materials for amplification and emission of THz radiation. Also\, combination of 2D materials with “classical” se miconductor materials like GaN and/or GaAs can lead to the production of m aterials with unprecedented THz properties.\nWe demonstrate different meth ods of manufacturing nanodevices based on graphene and other 2D related m aterials. These methods include both the fabrication of 2D heterostructure s from the micrometer scale to large surface area materials. We present st ep-by-step how to combine 2D materials with different materials\, e.g. sem iconductors\, and how to fabricate matrices of THz elements (detectors\, m etasurfaces). \nA comprehensive characterization of the basic electric and THz properties of these materials will be also presented. Preliminary res ults and theoretical analysis indicate the great potential of graphene-bas ed nanostructures for terahertz applications.\n\n**Acknowledgements**\nThe work was supported by the “International Research Agendas” program of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund (No. MAB/2018/9) for CENTERA. A.Kr ajewska was supported by the Foundation for Polish Science (FNP).\n\nhttps ://events.ncbj.gov.pl/event/75/contributions/795/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/795/ END:VEVENT BEGIN:VEVENT SUMMARY:THz spectroscopy of new materials for high frequency LTCC applicat ions DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-790@events.ncbj.gov.pl DESCRIPTION:Speakers: Norbert Pałka (Military University of Technology)\n The rapid development of modern 5G and 6G communication systems is connect ed with a increasing demand for new dielectric substrate materials\, which should provide higher signal transmission speed and miniaturization as we ll as possibility of passive component integration. Requirements for such new materials include a low dielectric constant to minimize signal propaga tion delay\, low dielectric losses for frequency selectivity and reduced e nergy consumption\, and a low sintering temperature to allow the use of mu lti-layer LTCC/ULTCC (low/ultra-high temperature ceramic fired). With the modification of materials with a low dielectric constant\, such as: silica \, borosilicate glasses\, cordierite\, mullite\, forsterite\, diopside\, w illemite\, aluminates\, which have been well known for decades\, less popu lar ceramics have recently appeared\, such as: as borates\, tungstates\, m olybdates\, vanadates\, and phosphates. The use of ceramic-ceramic or glas s–ceramic composites is an effective way to tailor microstructure\, elec tric\, and thermal properties of functional materials for microwave substr ates. \nIn particular\, this approach enables the production of layered st ructures with buried passive electronic components using advanced LTCC tec hnology\, which offers relatively low cost\, flexibility in design and pro duction\, a high degree of miniaturization and integration. Here\, we pres ent terahertz time domain characterization of a few selected materials inc luding their refractive indices and the absorption coefficients. This rese arch was funded by NATIONAL SCIENCE CENTRE\, Poland\, grant number 2019/35 /B/ST5/02674.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/790/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/790/ END:VEVENT BEGIN:VEVENT SUMMARY:Large inverted band-gap in strained three-layer InAs/GaInSb quantu m wells DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-789@events.ncbj.gov.pl DESCRIPTION:Speakers: Benoit Jouault (cnrs)\nQuantum spin Hall insulators (QSHIs) based on HgTe and three-layer InAs/GaSb quantum wells (QWs) have c omparable bulk band-gaps of about 10-18 meV. The former however features a band-gap vanishing with temperature\, while the gap in InAs/GaSb QSHIs is rather temperature-independent. We report on the realization of large inv erted band-gap in strained three-layer InAs/GaInSb QWs. By temperature-dep endent magnetotransport measurements of gated Hall bar devices\, we extrac t a gap as high as 45 meV. Combining local and non-local measurements\, we attribute the edge conductivity observed at temperatures up to 40 K to th e edge channels\, of possible topological origin\, with equilibration leng ths of a few micrometers. Our findings pave the way toward manipulating ed ge transport at high temperatures in QW heterostructures.\n\nhttps://event s.ncbj.gov.pl/event/75/contributions/789/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/789/ END:VEVENT BEGIN:VEVENT SUMMARY:Tunable CNT Surfaces for THz Wave Applications DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-777@events.ncbj.gov.pl DESCRIPTION:Speakers: Aleksandra Przewłoka (CENTERA Laboratories\, Instit ute of High Pressure Physics\, PAS )\, Dmitri Lioubtchenko (CENTERA Labora tories\, Institute of High Pressure Physics\, PAS )\nThe research and deve lopment in the frequency region of 0.1-1.0 THz is extremely significant fo r the wide range of applications\, such as telecommunication and imaging s ystems\, material spectroscopy\, medical imaging and treatments\, etc. Des pite the problems in technology and high prices for basic components (phas e shifters\, directional couplers\, etc.)\, the THz systems offer higher d ate rates for telecommunication\, high spatial resolution in the visualiza tion of objects\, small size of antennas and other elements. The state-of- the-art of the THz devices reveals serious problems with radiation sources with continuous wave semiconductor-based source\, electronically tunable phase shifters\, etc.\nCarbon nanotubes (CNT) offer unique properties due to their natural small dimensions and outstanding electrical properties. T heir tunability properties makes them very attractive in application to th e THz system. Integration of CNTs with the dielectric rod waveguide (DRW) technology transferred from cellulose membranes onto other substrates (sap phire DRW\, optical glass\, polished silicon) by direct dry transfer enabl es a novel technology platform for tunable THz systems.\nPhase shifter can be developed by introducing the optically controlled varactor to the DRW. The phase change of 10-20 deg with almost negligible change in attenuatio n less than 0.1 dB can be achieved in the frequency range of 75-500 GHz. B esides\, DRWs have no cut-off frequency enabling broad band operation.\nTh e effect of the dielectric constant tuning of single-walled carbon nanotub es under light illumination is observed in the very wide frequency range o f 0.1–1 THz. The optical absorption spectrum is not uniform and it consi sts of several absorption peaks related to electron transitions. Therefore \, the change of capacity and resistance under different light wavelength illumination is different at different wavelengths.\nThe losses are attrib uted to the electromagnetic absorption by the CNT layers with differences stemming from variations in nanotube densities and total lengths of the tr ansferred samples on the DRWs. The increased absorbance at lower frequenci es has also been previously observed for CNTs.\nCarbon based nanomaterials are perspective materials for very wide applications in millimeter wave a nd THz frequency range. Phase shifter based on DRW loaded with CNT layer i s a perspective candidate for ultra-wide band device application. The ultr a-wide band optically controlled CNT-based phase shifter can enable THz be am steering.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/777/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/777/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetospectroscopy of a CdTe/ Cd$_{0.8}$Mg$_{0.2}$Te quantum wel l DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-758@events.ncbj.gov.pl DESCRIPTION:Speakers: Jerzy Łusakowski (University of Warsaw)\nWe present results of magnetotransport and magnetospectroscopic studies on a single CdTe quantum well (QW) with Cd$_{0.8}$Mg$_{0.2}$Te barriers modulation-d oped with Iodine donors. Experiments were carried out at temperatures of a bout 1.8 K as a function of magnetic field up to 10 T and included measure ments of: transport\, THz transmission\, photoluminescence\, optically de tected cyclotron resonance (ODCR) and reflectivity in the visible range. \ n\nTransport measurements determined concentration of a two-dimensional el ectron gas (2DEG) in the CdTe QW to be $3.3\\times 10^{11}$ cm$^{-2}$ in t he darkness $3.4\\times 10^{11}$ cm$^{-2}$ after over the barrier illumina tion. These values were used to establish the filling factors in the anal ysis of optical spectra.\nTHz transmission measurements allowed us to dete rmine the effective mass of electrons which was to be $(0.1020\\pm0.0006) m_e$\, consistent with earlier studies on CdTe QWs. Magnetoluminescence spectra showed the Fermi-edge-singularity shape that is characteristic fo r the case of QWs with such a high 2DEG concentration and allowed us to ob serve a band-to-band recombination between Landau levels in the conduction and valence bands. Combined with the determined mass of the free electron \, this allowed us to determine the mass of the hole involved in the lumi nescence process. ODCR spectra showed that heating of 2DEG by absorption o f a THz radiation leads to redistribution of electrons between all observa ble Landau levels\, not just those adjacent to the Fermi energy. Reflecti vity measurements revealed the presence of multiple resonances and provide d valuable information about the energetical structure of levels of the QW under the influence of the internal electric field. \n\nIn conclcusio n\, we have shown on the example of CdTe/Cd$_{0.8}$Mg$_{0.2}$Te QW that th e combination of magnetotransport with THz and VIS magnetospectroscopy a llows for a thorough characterization of the structure of quantum levels in a two-dimensional system. The comprehensive procedure applied in our s tudy show the way to plan and carry out experiments on less known semicond uctor objects. \n\n\n \n \nThis research was partially supported by the Po lish National Science Centre grant UMO-2019/33/B/ST7/02858.\n\nhttps://ev ents.ncbj.gov.pl/event/75/contributions/758/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/758/ END:VEVENT BEGIN:VEVENT SUMMARY:3D printable materials for use in dual band optical structures DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-718@events.ncbj.gov.pl DESCRIPTION:Speakers: Michal Walczakowski (Military University of Technolo gy)\nPursuit after new technical and scientific achievement is a driving f orce for new solutions in research equipment. Furthermore\, highest ever c ompetition is pushing time of rapid development to the limits. Evolution o f science lead us to a place where two or more IR radiation wavelengths a re necessary to conduct some experiments. In some cases wavelength separat ion is significant\, mixing one from THz range and other from NIR of MIR. Working with whole IR spectrum is possible with usage of reflective optics . Inconvenience occurs when one have to work with THz range\, where optica l elements are significantly bigger. The 4” mirrors are standard and eve n 8”\, or bigger elements aren’t uncommon. This fact may impact experi mental setup layout and in cases of facilities like free electron laser\, where two wavelength operation is associated with doubling beam guiding in stallation\, simplifying even a part of it may be desirable. Guiding both THz and MIR can be done when using only reflective optics\, but there is v ery limited Materials that can be usable for manufacturing a passive optic al elements that work in both bands could lead to reduction of the number of elements. That can translate to experiment optimization\, reduce cost o f elements and shorter time of preparing experimental setup. \n\nIn these study selection of materials suitable for manufacturing of optical 3D stru ctures was presented. A number of samples with different thickness was pre pared and measured. The issue of the characterization of various materials in wide\, optical spectral range is a common day task\, unless material i tself behaves differently in situations when it is homogeneous and when it is formed in the 3D printing process.\n\nFirst\, samples were measured in THz range with the Time domain spectroscopy (TDS) in 0.3-2.5 THz (1 mm – 150 um) frequency band. Transmission of the materials was measured and attenuation coefficients were determined. Spectral characterization of t he samples in the range from 2 THz up to 1.5 um was conducted with FTIR sp ectroscopy. Based on this set of results influence of 3D print on the spec trum was shown. Discussion of the results includes influence of different polarization used in measurements\, effects occurring with samples of diff erent thickness and 3D printing side effects. \n\nThe objective is to ena ble designing of the optical elements using spectral properties of materia l combined with curvatures of the element. Design of optics that can work differently on two spectral bands takes advantage of implementing addition al features like wavelength selectivity in THz band or different focal poi nts.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/718/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/718/ END:VEVENT BEGIN:VEVENT SUMMARY:Mobility Spectrum Analysis for Electric Charge Carriers in HgCdTe/ HgTe/HgCdTe Quantum Well with Inverted Bands Order Close to Topological Tr ansition DTSTART;VALUE=DATE-TIME:20220706T153500Z DTEND;VALUE=DATE-TIME:20220706T155000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-753@events.ncbj.gov.pl DESCRIPTION:Speakers: Jacek Przybytek (CENTERA Laboratories\, Institute of High Pressure Physics\, Polish Academy of Sciences\, Poland & University of Warsaw\, Poland)\nBased on the experimental small-field magnetotranspor t measurements performed for 7.1 nm-width HgCdTe/HgTe/HgCdTe quantum well with inverted band structure order\, we will present results of the mobil ity spectra analysis in dependence on both the gate voltage (charge carrie r concentration) and temperature.\nWe will discuss these data from the poi nt of view of the band structure picture and possible scattering mechnisms of various types of carries in the system.\n\nhttps://events.ncbj.gov.pl/ event/75/contributions/753/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/753/ END:VEVENT BEGIN:VEVENT SUMMARY:Selected issues of influence irradiation on characteristics of sup erconducting elements in modern FEL-s facilities DTSTART;VALUE=DATE-TIME:20220706T145000Z DTEND;VALUE=DATE-TIME:20220706T150500Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-708@events.ncbj.gov.pl DESCRIPTION:Speakers: Jacek Sosnowski (NCBJ)\nCurrently developed free ele ctron lasers facilities more and more frequently use superconducting eleme nts in theirs advanced constructions. Most frequent examples of these appl ications are the superconducting electromagnets\, current leads to them an d especially superconducting cavities. The same concerns the superconducti ng shields\, as well as superconducting correction coils conducting the el ectron beam along the appropriate way. Beside of numerous advantages of us ing these new materials\, there arise however then new effects\, especiall y connected with the influence of the irradiation appearing in FEL acceler ators on the current carrying properties of the unique superconducting mat erials. The irradiation is caused here by primary electrons beam as well a s by secondary beams\,composed from neutrons\, gamma-rays and photons\, wh ich are created then. In the paper are discussed therefore the advantages but also problems arising\, while using superconductors in modern accelera tors\, working in irradiation environment. It is shown in which way the ir radiation effects damage the subtle structure of superconducting materials \, including 2D HTc superconductors\, in which columnar defects are formed . In the paper it will be analysed\, in which way these structural defects influence the current carrying properties of the superconducting material s. It will be developed therefore the energetical approach to the process of capturing on the nano-defects of the magnetic pancake vortices\, charac teristic for HTc superconductors. Various initial positions of the capture d vortices will be analysed\, movement of them will lead to the potential barrier decrease. The influence of the radiational defects on the current -voltage characteristics will be investigated then and maximal current den sity values detected\, as the function of irradiation intensity and physi cal parameters as magnetic field and temperature. These researches have th erefore pure scientific meaning as well as can be useful for prediction of the proper work of superconducting solenoids and current leads to them in radiational environmen. Analysis can be also extended on the case of micr o-cracks and dislocational defects formed during the mechanical winding of superconducting coils and arising then bending strain.\n\nhttps://events. ncbj.gov.pl/event/75/contributions/708/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/708/ END:VEVENT BEGIN:VEVENT SUMMARY:Shielding with Graphene Epoxy Composites in the Extended THF Band from 0.25 to 4.00 THz DTSTART;VALUE=DATE-TIME:20220706T140500Z DTEND;VALUE=DATE-TIME:20220706T142000Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-745@events.ncbj.gov.pl DESCRIPTION:Speakers: Kamil Stelmaszczyk (CENTERA Laboratories\, Institute of High Pressure Physics PAS\, Warsaw\, Poland)\nWe report on THz charact erization of graphene composites in the extended THF band from 0.25 to 4.0 0 THz. The composites\, containing low percent by weight fractions (wt.%) of graphene form 0.8wt.% to 1.2wt.%\, were investigated using THz- Time Do main Spectroscopy (THz-TDS). Based on the measured transmission and reflec tion coefficients\, the shielding effectiveness parameters of reflection ( SER) and transmission (SET) were calculated to determine the shielding eff ectiveness of absorption (SEA). The procedure comprised each of the weight fractions of graphene.\nWhile the SER was found to be less than ~0.6 dB w ithin the measured frequency range and for all the samples\, the SET and S EA were found to be substantially higher\, firmly above ~70 dB with graphe ne loading of 1.2wt.% at the frequency f=1.6 THz. Such unexpectedly high t otal shielding effectiveness resulted mostly from absorption\, due to the measured low absolute values of SER.\nThe fact that a simple EM energy red irection via conduction-based reflection was not primary energy loss mecha nism is favorable from the point of view of EMI shielding because contrary to metal-based conducting coatings or metallic nanocomposites\, the graph ene-based epoxy materials do not spread unwanted EM radiation from one pla ce to another. Additionally\, they have low weights.\nBy performing the Be er-Lambert calculations\, we show that even a thin-film or a spray coating with a thickness in the few-hundred-micrometer range of lightweight\, not conducting and not reflecting graphene epoxy composites can be sufficient for blocking THz radiation in many practical applications\, where the shi elding of EM by ~20–30 dB is typically sufficient. Thus\, the fabricated composites can be successfully used as effective ultra-thin stealth mater ials.\n\n[1]. Z. Barani\, K. Stelmaszczyk\, et al.\, Appl. Phys. Lett. 120 \, 063104 (2022)\n\nhttps://events.ncbj.gov.pl/event/75/contributions/745/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/745/ END:VEVENT BEGIN:VEVENT SUMMARY:Terahertz Time-Domain Spectroscopy for artworks analysis DTSTART;VALUE=DATE-TIME:20220706T135000Z DTEND;VALUE=DATE-TIME:20220706T140500Z DTSTAMP;VALUE=DATE-TIME:20260813T155649Z UID:indico-contribution-85-747@events.ncbj.gov.pl DESCRIPTION:Speakers: Ewelina Karpierz-Marczewska (CENTERA Laboratories\, Institute of High Pressure Physics PAS)\, Kamil Stelmaszczyk (CENTERA Labo ratories\, Institute of High Pressure Physics PAS)\nIn recent years\, tera hertz (THz) techniques have been used in many fields of applications\, mos t of all in space\, telecommunication and security industry. However\, the number of projects connecting THz technologies with Science and Culture i s constantly increasing and the conservation and restoration of art\, e.g. paintings or sculptures\, belongs to the most evolving areas in this doma in. \nThe conventional spectroscopic and imaging techniques for the analys is of art pieces comprise: X-ray\, Ultraviolet (UV)\, Infrared (IR) and la ser spectroscopy\, but even if well established\, they may have negative i mpact on the objects under analysis due to high energies of photons. Only IR reflectography is considered as safe method\, but in many cases it is s imply not sufficient. THz imaging is a non-invasive and safe technique whi ch extends spectral bands of X-ray and IR spectroscopies to lower and less invasive photon energies. Several years ago\, it was proposed for the stu dy of artworks and research in the Uffizi Gallery in Florence and recent d evelopments in THz technology\, in particular time domain techniques\, ena ble easier and more effective usage of THz radiation in the field of art c onservation.\nThe best established and most promising THz time domain tech nique is known as Terahertz Time Domain Spectroscopy (THz-TDS). It can be used to characterize and identify various materials in the THz wavelength range\, basing on the intensity of the wave passing through the sample or the wave reflected from it. In addition\, the measurement of the phase of the THz wave makes it possible to study the parameters characterizing macr oscopic electromagnetic properties of materials\, as extension to typical molecular absorption spectra.\nInspired by successful applications of THz techniques in the Uffizi Gallery in Florence\, the Louvre in Paris or muse ums in Milan\, we decided at CENTERA to prepare THz-TDS experiments\, whic h provide new information about the internal physical structure of painti ngs or frescos such as canvases\, paper and even dry plaster. THz waves ha ve good penetration depths in all these materials (~1 cm) and with broad s pectral bandwidth of ps THz pulses (0.1 - 10 THz)\, it is be possible to i dentify the substances that the paint consists of basing on the registrati on of THz absorption spectra. As a result\, one can learn about such prope rties of the analysed pieces of arts such as the depths of subsequent pain t layers or pigments. \nDuring investigations a specially prepared picture has been used. It was prepared using two types of paints: oil and acrylic \, covering its selected areas with different amount of varnish (different layer thickness). Then the whole painting was painted over with white pai nt. Two dimensional (x-y) scans of the entire painting were made with THz- TDS spectrometer in both transmission and reflection modes with the resolu tion better than 1 mm. The obtained results will be presented on the poste r.\n\nhttps://events.ncbj.gov.pl/event/75/contributions/747/ LOCATION:Novotel Warszawa Centrum Róża URL:https://events.ncbj.gov.pl/event/75/contributions/747/ END:VEVENT END:VCALENDAR