Protecting the HERMES Experiment from Synchrotron Radiation

The vast improvement of the sensitivity of modern ground-based air Cherenkov telescopes, together with the sensitive flux measurements at lower frequencies, requires accurate elaborations of the theoretical radiation models for flaring blazars. Here the flaring of TeV blazars due to the synchrotron-self Compton (SSC) process is considered. We assume that, at the moment t = t0, a flare in the emission knot occurs due to the instantaneous injection of monoenergetic (E0) ultrarelativistic electrons. The ultrarelativistic electrons are injected uniformly over the knot volume and at later times are subject to linear synchrotron radiation cooling in a magnetic field whose strength remains constant during the time evolution of the relativistic electrons.The generated synchrotron photons are subject to multiple Thomson-scattering off the cold electrons in the source giving rise to spatial photon diffusion. Optically thick and thin synchrotron radiation intensities and photon density distributions in the emission knot as functions of frequency and time are analytically determined. The synchrotron photons serve as target photons for the SSC process, which is calculated in the optically thin frequency range using the Thomson approximation of the inverse Compton cross section. It is shown that the optically thick part of the synchrotron radiation process provides a negligible contribution to the resulting SSC intensity at all frequencies and times.Because the high-energy TeV photons undergo no elastic multiple Compton scatterings, we neglect the influence of photon diffusion in the calculation of the SSC intensity and fluence distribution with energy. The SSC fluence exhibits a break at Ef = 15.8b −1/3 GeV from a ∝E −1/4 s -power law spectrum at lower photon energies Et ≤ Es ≤ Ef to a ∝E −2 s [1 − (Es/E0)

The role of Compton cooling in the standard model for the afterglows of gamma-ray bursts is considered. When electrons cool by scattering off their own synchrotron photons, three cooling regimes are identified in which the observed synchrotron radiation exhibits qualitatively different characteristics. Depending on the values of the source parameters, an afterglow may evolve through one, two, or all three of these regimes. Since synchrotron radiation can be regarded as Compton scattering of the virtual photons due to the magnetic field, in one of these regimes the instantaneous synchrotron spectrum has properties identical to those when Compton cooling is negligible. During this phase in the evolution, the synchrotron radiation falls mainly in the near-infrared/optical/UV spectral range. In order to break this degeneracy, good temporal coverage is needed. Alternatively, the importance of Compton scattering can be determined for those afterglows that are observed outside this degeneracy phase. It is suggested that the afterglows of GRB 980923 and GRB 971214 are two such cases. In the prompt afterglow of GRB 980923, the Klein-Nishina limit suppresses Compton scattering, and the cooling is due to synchrotron radiation. However, the derived values of the source parameters are such that Compton cooling is expected to have been important in its subsequent evolution. The observed properties of GRB 971214 indicate cooling to be dominated by Compton scattering rather than synchrotron radiation. If Compton cooling is generally important in the afterglows of gamma-ray bursts, the likelihood of the shock becoming radiative is increased. It is suggested that this effect contributes to the low frequency of detected afterglows.

The Schr\"odinger equation for the system, formed by resonant nuclei incorporated in a lattice interacting with synchrotron radiation pulses, has been solved for times directly after the delivery of the pulse. The general problem of synchrotron radiation interacting with nuclear resonant material has been treated previously for all times using a number of different approaches including the nuclear-exciton model. This model assumes the nuclear exciton is formed immediately after the synchrotron radiation pulse. Here it is found that the synchrotron photons, having energies close to the nuclear resonance energy, disappear from the pulse according to an exponential law. The decay constant of the exponential is equal to a natural radiative decay constant multiplied by a number related to the nuclear resonant thickness of the sample. The formation of the exciton can be characterized by a time constant that is the inverse of this decay constant. Thus, the time constant for forming the nuclear exciton is inversely proportional to the sample thickness. This justifies the hypothesis, in the nuclear-exciton model, that the nuclear exciton is formed promptly after the synchrotron radiation flash.

The synchrotron radiation light produced from a dipole magnet is widely used to characterize beam parameters in synchrotron light source (photon synchrotron). The synchrotron radiation monitor (SRM) systems were implemented for the booster synchrotron and the storage ring at Taiwan Photon Source (TPS). The beam parameters of the booster were recorded during the energy ramping process through the CCD camera and streak camera. The beam size measurement and beam behavior observed of the storage ring were performed by X-ray pinhole camera and streak camera respectability. The results are summarized in this report.

We investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P ≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P ≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasiuniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization.

Synchrotron radiation is a unique source of infrared radiation being highly polarized, pulsed, with the broad emission band and about thousand times brighter than standard thermal source. All just mentioned synchrotron radiation adventures apply to a large choice of experimental techniques and investigations. Among them are high-pressure studies, earth science and biology, microspectroscopy, reflectance and absorption spectroscopy for surface study, time-resolved spectroscopy and ellipsometry. Interest in infrared synchrotron radiation goes back to the 1980s (Duncan & Williams, 1983). At present numerous infrared beamlines have been developed at synchrotron radiation facilities throughout the world, see, e. g., (Bocci et al., 2008; Carr & Dumas, 1999; Guidi et al., 2005; H. Kimura et al., 2001; S. Kimura et al., 2001; S. Kimura et al., 2006; Roy et al., 2006; Williams & Dumas, 1997). Efforts to improve the radiation beam characteristics lead to elaboration more and more sophisticated beamline optics. To achieve this goal, we need to know all characteristics of emitted radiation, its intensity distribution, polarization and phase distribution. In particular, the synchrotron radiation wave properties play a major role in conventional diagnostics of electron beams in storage rings (Andersson et al., 2006; Elleaume et al., 1995; Fang et al., 1996; Flanagan et al., 1999; Hs & Huang, 1993; Weitkamp et al., 2001). In this case, the image of the electron beam is formed by an optical lens. The synchrotron radiation diffraction on the lens iris aperture restricts the resolution of the beam profile measurements. Infrared synchrotron radiation was used for longitudinal beam diagnostics at FLASH free electron laser (Grimm et al., 2008; Paech et al., 2006, 2007). Recent trends show an increased usage of synchrotron radiation interferometers for high precision measurements of the electron beam sizes (Artemiev et al., 1996; Chubar, 1995; Hiramatsu et al., 1999; Katoh & Mitsuhashi, 1999; Naito & Mitsuhashi, 2010). For proper interpretation of observed data, we also need to know synchrotron radiation phase distributions.

view Abstract Citations (7) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A model for simultaneous synchrotron and inverse Compton fluxes. Peterson, F. W. ; King, C., III Abstract Optical and radio fluxes, possibly correlated, from two extragalactic variable radio sources are analyzed on the assumption that the radio flux is synchrotron radiation whereas the optical flux is inverse Compton radiation resulting from scattering of the synchrotron photons. Detailed analysis of an outburst in 3C 120 shows that a description of the evolution of the outburst, based on this interpretation, is compatible with its description on the basis of the adiabatic expansion model in all respects but the rate of falloff of the optical flux. Compton optical and X-ray fluxes are calculated for the 1972 radio flare in Cygnus X-3. Subject headings: quasi-stellar sources or objects - radio sources - synchrotron radiation - X-ray sources Publication: The Astrophysical Journal Pub Date: February 1975 DOI: 10.1086/153378 Bibcode: 1975ApJ...195..753P full text sources ADS | data products SIMBAD (1) NED (1)

Background: Deep x-ray lithography using synchrotron radiation is a prominent technique in the fabrication of high aspect ratio microstructures. The minimum lateral dimensions producible are limited by the primary dose distribution and secondary effects (Fresnel diffraction, secondary electrons scattering, etc.) during exposure. Aim: The influence of secondary radiation effects on the fabrication of high aspect ratio microstructures with submicrometer lateral dimension by deep x-ray lithography is characterized. Approach: The microstructures under investigation are one-dimensional gratings. The influence of secondary effects on structural dimension is simulated and compared to the experimental results. The quality criteria and possible defects arising in experiments highlight the importance of the mechanical stability of the photoresist. Results: From the simulation results, the minimum period of microstructures that can be produced is about 600 nm. Experimentally, microstructures with 1.2 μm minimum period (resist width of ∼700 nm) and height of ∼10 μm could be fabricated. Conclusions: Simulation results show the feasibility for fabricating gratings with a period less than 1 μm. To achieve these values also in experiment, it is necessary to increase the mechanical stability of the high aspect lamellae. The outcome of these results allows one to reduce the expensive and lengthy product development cycle.

A theoretical radiation model for the flaring of TeV blazars is discussed here for the case of a nonlinear electron synchrotron cooling in these sources. We compute analytically the optically thick and thin synchrotron radiation intensities and photon density distributions in the emission knot as functions of frequency and time followed by the synchrotron self-Compton intensity and fluence in the optically thin frequency range using the Thomson approximation of the inverse Compton cross section. At all times and frequencies, the optically thin part of the synchrotron radiation process is shown to provide the dominant contribution to the synchrotron self-Compton quantities, while the optically thick part is always negligible. Afterwards, we compare the linear to the nonlinear synchrotron radiation cooling model using the data record of PKS 2155-304 on MJD 53944 favouring a linear cooling of the injected monoenergetic electrons. The good agreement of both the linear and the nonlinear cooling model with the data supports the relativistic pickup process operating in this source. Additionally, we discuss the synchrotron self-Compton scattering, applying the full Klein-Nishina cross section to achieve the most accurate results for the synchrotron self-Compton intensity and fluence distributions.

The Targeted Protein Research Program (TPRP) started in 2007 as a sequel of the Protein 3000 Project which lasted from 2002 to 2007. In the new project, four cores, Protein Production, Structure Analysis, Control of Protein Functions with Compounds, and Informatics, have been established as focus of methodology developments critical for functional and structural studies by the target protein research teams. Within the "Analysis Core" synchrotron radiation plays a pivotal role providing X-ray beams for structural analyses of the target proteins. The two large Japanese synchrotron radiation facilities, SPring-8 and Photon Factory (PF), along with three protein crystallography groups from Hokkaido, Kyoto and Osaka Universities have teamed up to develop two complementary micro-beam beamlines, one on each synchrotron site, and associated technologies for cutting edge structural biology research. At the PF, there are 5 operational beamlines which are equipped with state-of-the-art instrumentation for high-throughput protein crystallography experiments. Within the TPRP framework, the PF is developing a micro-focus beamline optimized for a lower energy single anomalous diffraction (SAD) experiment. This will be particularly useful for structure determination of difficult protein targets for which heavy atom derivatives or selenomethionine substitution does not work and other standard phasing methods fail to give structure solutions. This will augment the capabilities of the PF structural biology beamlines with similar look-and-feel experimental environments.

Internal energy effects in the reactivity of CO 22+ doubly charged molecular ions with CO 2 and CO

Photon-induced field desorption of hydrogen ions from a tungsten emitter has been observed using laser light (4.5 eV). Whereas the laser light leads to thermal desorption, the synchrotron radiation seems to show a threshold ≥ 30 eV and is therefore concluded to be a quantum process.

Electronic structure and fano-type resonance effects in uranium antimonide studied by photoemission with synchrotron radiation

Local structure of amorphous MO 50Ni 50 determined by anomalous x-ray scattering using synchroton radiation

The dissociative photoionization channels of gaseous Si(CH3)Cl3 and ion desorption mechanisms of solid-state analogs following valence-level excitation have been investigated by means of photoionization mass spectroscopy, threshold photoelectron spectroscopy (TPES), and photon-stimulated ion desorption (PSID) using synchroton radiation. The adiabatic ionization threshold of the parent molecular ion was determined to be 11.18 eV, consistent with the value of 11.16 eV obtained from the TPES spectrum. An energy shift ∼0.8 eV toward lower binding energies for the orbitals of solid Si(CH3)Cl3 with respect to the gas phase values was observed. Two thresholds at 14.97 and 17.51 eV in the CH3+ photoionization efficiency spectrum are probably associated with the ionization of 2e″ and 11a1 orbitals, respectively. The H+ desorption threshold at 20.1 eV in the PSID spectrum may be attributed to the excitation of C 2s electron correlation states to the unoccupied states. The Cl+ desorption threshold at 19.9 eV is likely initiated by an Auger-stimulated desorption process.