scholarly journals Ultra-monochromatic far-infrared Cherenkov diffraction radiation in a super-radiant regime

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
P. Karataev ◽  
K. Fedorov ◽  
G. Naumenko ◽  
K. Popov ◽  
A. Potylitsyn ◽  
...  
Keyword(s):  
Spectral Range ◽  
Far Infrared ◽  
High Energy ◽  
Spectral Lines ◽  
Diffraction Radiation ◽  
Photon Yield ◽  
Non Invasive ◽  
Relative Bandwidth ◽  
Advanced Tool ◽  
Fast Charged Particle

AbstractNowadays, intense electromagnetic (EM) radiation in the far-infrared (FIR) spectral range is an advanced tool for scientific research in biology, chemistry, and material science because many materials leave signatures in the radiation spectrum. Narrow-band spectral lines enable researchers to investigate the matter response in greater detail. The generation of highly monochromatic variable frequency FIR radiation has therefore become a broad area of research. High energy electron beams consisting of a long train of dense bunches of particles provide a super-radiant regime and can generate intense highly monochromatic radiation due to coherent emission in the spectral range from a few GHz to potentially a few THz. We employed novel coherent Cherenkov diffraction radiation (ChDR) as a generation mechanism. This effect occurs when a fast charged particle moves in the vicinity of and parallel to a dielectric interface. Two key features of the ChDR phenomenon are its non-invasive nature and its photon yield being proportional to the length of the radiator. The bunched structure of the very long electron beam produced spectral lines that were observed to have frequencies upto 21 GHz and with a relative bandwidth of 10–4 ~ 10–5. The line bandwidth and intensity are defined by the shape and length of the bunch train. A compact linear accelerator can be utilized to control the resonant wavelength by adjusting the bunch sequence frequency.

scholarly journals NEW EXPERIMENTAL RESULTS WITH OPTICAL DIFFRACTION RADIATION DIAGNOSTICS

2010 ◽  
Vol 25 (supp01) ◽  
pp. 189-200
Author(s):  
E. CHIADRONI ◽  
M. CASTELLANO ◽  
A. CIANCHI ◽  
K. HONKAVAARA ◽  
G. KUBE
Keyword(s):  
Angular Distribution ◽  
Forward Direction ◽  
High Energy ◽  
Optical Diffraction ◽  
Diffraction Radiation ◽  
Light Sources ◽  
Transverse Beam ◽  
Non Invasive ◽  
High Charge Density ◽  
Set Up

The characterization of the transverse phase space for high charge density and high energy electron beams is demanding for the successful development of the next generation light sources and linear colliders. Due to its non-invasive and non-intercepting features, Optical Diffraction Radiation (ODR) is considered as one of the most promising candidates to measure the transverse beam size and angular divergence. The recent results of our experiment, based on the detection of the ODR angular distribution to measure the electron beam transverse parameters and set up at FLASH (DESY), are presented. A thin stainless steel mask has been installed at 45° with respect to the DR target and normally to the beam propagation to reduce the contribution of synchrotron radiation (SR) background. In addition, interference between the ODR emitted on the shielding mask in the forward direction and the radiation from the DR target in the backward direction is observed. This is what we call Optical Diffraction Interferometry (ODRI). The contribution of this interference effect to the ODR angular distribution pattern and, consequently, its impact on the beam transverse parameters is discussed.

scholarly journals POS1388 ULTRASOUND FOR PANNICULITIS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 977.1-977
Author(s):  
A. Potapova ◽  
O. Egorova ◽  
O. Alekseeva ◽  
A. Volkov ◽  
S. Radenska-Lopovok
Keyword(s):  
Dynamic Range ◽  
Subcutaneous Fat ◽  
Diagnostic Value ◽  
High Energy ◽  
Contralateral Side ◽  
Imaging Method ◽  
Non Invasive ◽  
M 12

Background:Ultrasound (US) is a non-invasive and safe imaging method that allows in vivo differentiation of the morphological structures of subcutaneous fat (SCF) tissue in in normal and pathology.Objectives:Reveal features of ultrasound changes in SCF in panniculitis (Pn).Methods:57 patients (f – 45, m - 12) aged 18 - 67 years with an initial diagnosis of erythema nodosum and a disease duration of 3.6 ± 1.4 years were examined. In addition to the general clinical examination, a computed tomography of the chest organs and a pathomorphological examination of a skin biopsy from the site of the node were performed. Ultrasound was performed on a MyLabTwice apparatus (ESAOTE, Italy) using a multi-frequency linear transducer (10-18 MHz) with the PD technique, the parameters of which were adapted for recording low-speed flows (PRF 300-600 Hz, low filter, dynamic range - 20-40 dB), the presence of vascularization was assessed not only in the affected area, but also on the contralateral side using high-energy Doppler.Results:33 patients were diagnosed with septal Pn (SPn), 24 - lobular Pn (LPn). In all cases, the diagnosis was verified by histological examination. Ultrasound made it possible to assess the thickness, echoicity and vascularization of the SCF. In 35 patients, significant thickening of the SCF was revealed (as compared to the contralateral side), of which in 14 cases with SPn, in 21 - with LPn. Significant diffuse thickening of the SCF with the contralateral side was observed in 18 patients, incl. in 12 (66%) patients with LPn. Limited thickening was more typical for SPn (73%). A significant increase in the echoicity of the SCF was noted in all forms of Pn. A “lobular” echo pattern with an anechogenic environment was observed in 25 patients, of which 18 (72%) had LPn. An increase in vascularization compared to the contralateral side was recorded in 30 cases (SPn-17, LPn-13).Conclusion:The obtained preliminary results indicate the important role of ultrasound in assessing the depth and prevalence of the inflammatory process at Pn. To clarify the diagnostic value of this method, further studies are needed on a larger sample of patients.Disclosure of Interests:None declared

scholarly journals Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

2021 ◽  
Vol 8 (3) ◽  
pp. 41
Author(s):  
Fardin Khalili ◽  
Peshala T. Gamage ◽  
Amirtahà Taebi ◽  
Mark E. Johnson ◽  
Randal B. Roberts ◽  
...  
Keyword(s):  
Pressure Fluctuations ◽  
High Energy ◽  
Sound Sources ◽  
Severity Level ◽  
Non Invasive ◽  
Flow Through ◽  
Severity Of The Disease ◽  
Proper Orthogonal ◽  
Different Levels

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis. The frequency spectral analysis and proper orthogonal decomposition unveiled the frequency contents of the fluctuations for different severities and decomposed the flow into several frequency bandwidths. Results showed that high-intensity turbulent pressure fluctuations appeared inside the stenosis for severities above 70%, concentrated at plaque surface, and immediately in the post-stenotic region. Analysis of these fluctuations with the progression of the stenosis indicated that (a) there was a distinct break frequency for each severity level, ranging from 40 to 230 Hz, (b) acoustic spatial-frequency maps demonstrated the variation of the frequency content with respect to the distance from the stenosis, and (c) high-energy, high-frequency fluctuations existed inside the stenosis only for severe cases. This information can be essential for predicting the severity level of progressive stenosis, comprehending the nature of the sound sources, and determining the location of the stenosis with respect to the point of measurements.

Astronomy on Ice

1986 ◽  
Vol 6 (4) ◽  
pp. 403-415 ◽  
Author(s):  
Martin A. Pomerantz
Keyword(s):  
Gamma Ray ◽  
Far Infrared ◽  
The United States ◽  
High Energy ◽  
Observational Cosmology ◽  
Significant Information ◽  
Infrared Measurements ◽  
Energy Gamma ◽  
Low Humidity ◽  
Scientific Station

AbstractThe geographic South Pole, where the United States maintains a year-round scientific station, affords a number of unique advantages for certain types of astronomical observations. These include: continuous viewing and constant declination of ail objects in the southern celestial hemisphere, exceedingly low humidity, extended periods of coronal seeing, high altitude, and uniform terrain. The areas of research that have already benefited immensely from thèse extraordinary features are helioseismology and submillimeter astronomy. Unparalleled observations of global solar oscillations have already yielded significant information about the structure and dynamics of the Sun’s interior. Far infrared measurements of various galactic and extra-galactic regions have attained an unprecedented level of sensitivity, limited for the first time only by the noise inherent in the detector. In addition to further helioseismological observations, currently planned future activities include observational cosmology and ultra high energy gamma ray astronomy.

scholarly journals Hidden molecular outflow in the LIRG Zw 049.057

2018 ◽  
Vol 609 ◽  
pp. A75 ◽  
Author(s):  
N. Falstad ◽  
S. Aalto ◽  
J. G. Mangum ◽  
F. Costagliola ◽  
J. S. Gallagher ◽  
...  
Keyword(s):  
Far Infrared ◽  
Minor Axis ◽  
Spectral Lines ◽  
Continuum Emission ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Nuclear Activity ◽  
Molecular Outflow ◽  
The Galaxy ◽  
Excitation Conditions

Context. Feedback in the form of mass outflows driven by star formation or active galactic nuclei is a key component of galaxy evolution. The luminous infrared galaxy Zw 049.057 harbours a compact obscured nucleus with a possible far-infrared signature of outflowing molecular gas. Due to the high optical depths at far-infrared wavelengths, however, the interpretation of the outflow signature is uncertain. At millimeter and radio wavelengths, the radiation is better able to penetrate the large columns of gas and dust responsible for the obscuration. Aims. We aim to investigate the molecular gas distribution and kinematics in the nucleus of Zw 049.057 in order to confirm and locate the molecular outflow, with the ultimate goal to understand how the nuclear activity affects the host galaxy. Methods. We used high angular resolution observations from the Submillimeter Array (SMA), the Atacama Large Millimeter/submillimeter Array (ALMA), and the Karl G. Jansky Very Large Array (VLA) to image the CO J = 2–1 and J = 6–5 emission, the 690 GHz continuum, the radio centimeter continuum, and absorptions by rotationally excited OH. Results. The CO line profiles exhibit wings extending ~ 300 km s-1 beyond the systemic velocity. At centimeter wavelengths, we find a compact (~ 40 pc) continuum component in the nucleus, with weaker emission extending several 100 pc approximately along the major and minor axes of the galaxy. In the OH absorption lines toward the compact continuum, wings extending to a similar velocity as for the CO are only seen on the blue side of the profile. The weak centimeter continuum emission along the minor axis is aligned with a highly collimated, jet-like dust feature previously seen in near-infrared images of the galaxy. Comparison of the apparent optical depths in the OH lines indicate that the excitation conditions in Zw 049.057 differ from those within other OH megamaser galaxies. Conclusions. We interpret the wings in the spectral lines as signatures of a nuclear molecular outflow. A relation between this outflow and the minor axis radio feature is possible, although further studies are required to investigate this possible association and understand the connection between the outflow and the nuclear activity. Finally, we suggest that the differing OH excitation conditions are further evidence that Zw 049.057 is in a transition phase between megamaser and kilomaser activity.

Optical parametric generation of high-energy femtosecond pulses in the 1-3 μm spectral range using BiB 3 O 6

2007 ◽  
Author(s):  
Valentin Petrov ◽  
Masood Ghotbi ◽  
Pancho Tzankov ◽  
Frank Noack ◽  
Ivailo Nikolov ◽  
...  
Keyword(s):  
Spectral Range ◽  
High Energy ◽  
Femtosecond Pulses ◽  
Parametric Generation ◽  
Optical Parametric ◽  
Optical Parametric Generation

scholarly journals Anthracene-Based Down-Converting Copolymers for Non-Invasive Optogenetic Techniques

2020 ◽  
Author(s):  
David French ◽  
Aundrea F. Bartley ◽  
Kavitha Abiraman ◽  
Micah Bagley ◽  
Benjamin Grant ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Methyl Methacrylate ◽  
Physical Properties ◽  
Emission Intensity ◽  
High Energy ◽  
Neuronal Cultures ◽  
Non Invasive ◽  
Solid States ◽  
Neurological Response ◽  
Down Conversion

<p>The down-conversion of high energy light with a fluorescent material may provide sufficient emission intensity to invoke a measurable neurological response in optogentically-active neurons. This work describes the use of anthracene-containing copolymers for use as a fixed emission material in optogenetic electrophysiology to demonstrate the feasibility of this technique. An anthracene-modified methacrylate was synthesized and copolymerized with methyl methacrylate to produce glassy copolymers with physical properties like those of poly(methyl methacrylate) (PMMA). The fluorescence in both solution and solid states are like those of pure anthracene and overlap fully with the absorption spectrum of channelrhodpsin-2. Scintillation is observed but is weak compared to fluorescence. The copolymers were found to be non-toxic to neuronal cultures. Whole cell patching measured the voltage changes of neurons under UV-irradiation in the absence and presence of a copolymer film. Increased frequencies and amplitudes of electrical events were observed in the presence of the polymers. </p> <div> <hr> </div>

scholarly journals The Far-Infrared emission of the first (z ∼ 6) massive galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 246-247
Author(s):  
George H. Rieke ◽  
Maria Emilia De Rossi ◽  
Irene Shivaei ◽  
Volker Bromm ◽  
Jianwei Lyu
Keyword(s):  
Interstellar Dust ◽  
Far Infrared ◽  
High Energy ◽  
Infrared Emission ◽  
High Energy Density ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Massive Galaxies ◽  
Very High Energy ◽  
Lower Redshift

AbstractThe first massive galaxies (z ∼ 6) have (1) very high energy density due to their small diameters and extreme luminosities in young stars and (2) interstellar dust relatively deficient in carbon compared with silicates. Both of these attributes should raise their interstellar dust temperatures compared with lower redshift galaxies. Not only is this temperature trend observed, but the high-z spectral energy distributions (SEDs) are very broad due to very warm dust. As a result total infrared luminosities – and star formation rates – at the highest redshifts estimated by fitting blackbodies to submm- and mm-wave observations can be low by a factor of ∼2.

scholarly journals Quality Control and Structural Assessment of Anisotropic Scintillating Crystals

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 376 ◽  
Author(s):  
Luigi Montalto ◽  
Pier Natali ◽  
Lorenzo Scalise ◽  
Nicola Paone ◽  
Fabrizio Davì ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Energy Physics ◽  
Radiation Detectors ◽  
Structural Condition ◽  
High Energy ◽  
Complete Characterization ◽  
Non Invasive ◽  
Light Production ◽  
Core Elements ◽  
Stress States

Nowadays, radiation detectors based on scintillating crystals are used in many different fields of science like medicine, aerospace, high-energy physics, and security. The scintillating crystals are the core elements of these devices; by converting high-energy radiation into visible photons, they produce optical signals that can be detected and analyzed. Structural and surface conditions, defects, and residual stress states play a crucial role in their operating performance in terms of light production, transport, and extraction. Industrial production of such crystalline materials is a complex process that requires sensing, in-line and off-line, for material characterization and process control to properly tune the production parameters. Indeed, the scintillators’ quality must be accurately assessed during their manufacture in order to prevent malfunction and failures at each level of the chain, optimizing the production and utilization costs. This paper presents an overview of the techniques used, at various stages, across the crystal production process, to assess the quality and structural condition of anisotropic scintillating crystals. Different inspection techniques (XRD, SEM, EDX, and TEM) and the non-invasive photoelasticity-based methods for residual stress detection, such as laser conoscopy and sphenoscopy, are presented. The use of XRD, SEM, EDX, and TEM analytical methods offers detailed structural and morphological information. Conoscopy and sphenoscopy offer the advantages of fast and non-invasive measurement suitable for the inspection of the whole crystal quality. These techniques, based on different measurement methods and models, provide different information that can be cross-correlated to obtain a complete characterization of the scintillating crystals. Inspection methods will be analyzed and compared to the present state of the art.

Sign in / Sign up

Export Citation Format

Share Document