Showing papers on "Synchrotron radiation published in 2010"

Fermi Large Area Telescope Observations of the Crab Pulsar and Nebula

Abstract: We report on γ -ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nan¸cay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first γ -ray peak leads the radio main pulse by (281 ± 12 ± 21) μs, giving new constraints on the production site of non-thermal emission in pulsar magnetospheres. The first uncertainty is due to γ -ray statistics, and the second arises from the rotation parameters. The improved sensitivity and the unprecedented statistics afforded by the LAT enable precise measurement of the Crab Pulsar spectral parameters: cut-off energy at Ec = (5.8 ± 0.5 ± 1.2) GeV, spectral index of Γ = (1.97 ± 0.02 ± 0.06) and integral photon flux above 100 MeV of (2.09 ± 0.03 ± 0.18) × 10−6 cm−2 s−1. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Pulsed γ -ray photons are observed up to ∼20 GeV which precludes emission near the stellar surface, below altitudes of around 4–5 stellar radii in phase intervals encompassing the two main peaks. A detailed phase-resolved spectral analysis is also performed: the hardest emission from the Crab Pulsar comes from the bridge region between the two γ -ray peaks while the softest comes from the falling edge of the second peak. The spectrum of the nebula in the energy range 100 MeV–300 GeV is well described by the sum of two power laws of indices Γsync = (3.99 ± 0.12 ± 0.08) and ΓIC = (1.64 ± 0.05 ± 0.07), corresponding to the falling edge of the synchrotron and the rising edge of the inverse Compton (IC) components, respectively. This latter, which links up naturally with the spectral data points of Cherenkov experiments, is well reproduced via IC scattering from standard magnetohydrodynamic nebula models, and does not require any additional radiation mechanism.

Global cosmic-ray-related luminosity and energy budget of the Milky Way

Abstract: We use the GALPROP code for cosmic-ray (CR) propagation to calculate the broadband luminosity spectrum of the Milky Way related to CR propagation and interactions in the interstellar medium. This includes γ-ray emission from the production and subsequent decay of neutral pions (π^0), bremsstrahlung, and inverse Compton scattering, and synchrotron radiation. The Galaxy is found to be nearly a CR electron calorimeter, but only if γ-ray emitting processes are taken into account. Synchrotron radiation alone accounts for only one-third of the total electron energy losses with ~10%-20% of the total synchrotron emission from secondary CR electrons and positrons. The relationship between far-infrared and radio luminosity that we find from our models is consistent with that found for galaxies in general. The results will be useful for understanding the connection between diffuse emissions from radio through γ-rays in "normal" (non-active galactic nucleus dominated) galaxies as well as for estimating the broadband extragalactic diffuse background from these kinds of galaxies.

Global cosmic-ray related luminosity and energy budget of the Milky Way

Abstract: We use the GALPROP code for cosmic-ray (CR) propagation to calculate the broad-band luminosity spectrum of the Milky Way related to CR propagation and interactions in the interstellar medium. This includes gamma-ray emission from the production and subsequent decay of neutral pions, bremsstrahlung, and inverse Compton scattering, and synchrotron radiation. The Galaxy is found to be nearly a CR electron calorimeter, but {\it only} if gamma ray emitting processes are taken into account. Synchrotron radiation alone accounts for only one third of the total electron energy losses with ~10-20% of the total synchrotron emission from secondary CR electrons and positrons. The relationship between far-infrared and radio luminosity that we find from our models is consistent with that found for galaxies in general. The results will be useful for understanding the connection between diffuse emissions from radio through gamma rays in ``normal'' (non-AGN dominated) galaxies, as well as for estimating the broad-band extragalactic diffuse background from these kinds of galaxies.

Reconciling observed GRB prompt spectra with synchrotron radiation

Abstract: (abridged)Prompt GRB emission is often interpreted as synchrotron radiation from high-energy electrons accelerated in internal shocks. Fast synchrotron cooling predicts that the photon index below the spectral peak is alpha=-3/2. This differs significantly from the observed median value alpha \approx -1. We quantify the influence of inverse Compton and adiabatic cooling on alpha to understand whether these processes can reconcile the observations with a synchrotron origin. We use a time-dependent code that follows both the shock dynamics and electron energy losses. We investigate the dependence of alpha on the parameters of the model. Slopes between -3/2 and -1 are reached when electrons suffer IC losses in the Klein-Nishina regime. This does not necessarily imply a strong IC component in the Fermi/LAT range because scatterings are only moderately efficient. Steep slopes require that a large fraction (10-30%) of the dissipated energy is given to a small fraction ( 50%) when adiabatic cooling is comparable with radiative cooling (marginally fast cooling). This requires collisions at small radii and/or with low magnetic fields. Amending the standard fast cooling scenario to account for IC cooling naturally leads to alpha up to -1. Marginally fast cooling may also account for alpha up to -2/3, although the conditions required are more difficult to reach. About 20% of GRBs show spectra with slopes alpha>-2/3. Other effects, not investigated here, such as a thermal component in the electron distribution or pair production by HE photons may further affect alpha. Still, the majority of observed GRB prompt spectra can be reconciled with a synchrotron origin, constraining the microphysics of mildly relativistic internal shocks.

Effects of pulsed, spatially fractionated, microscopic synchrotron X-ray beams on normal and tumoral brain tissue.

Abstract: Microbeam radiation therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50–600 keV, produced by third generation synchrotron sources, such as the European Synchrotron Radiation Facility (ESRF), in France. The main advantages of highly brilliant synchrotron sources are an extremely high dose rate and very small beam divergence. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. The minimal beam divergence results in the advantage of steeper dose gradients delivered to a tumor target, thus achieving a higher dose deposition in the target volume in fractions of seconds, with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has yielded many results from preclinical trials based on different animal models, including mice, rats, piglets and rabbits. Typically, MRT uses arrays of narrow (∼25–100 μm wide) microplanar beams separated by wider (100–400 μm centre-to-centre) microplanar spaces. The height of these microbeams typically varies from 1 to 100 mm, depending on the target and the desired preselected field size to be irradiated. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues, up to ∼2 yr after irradiation, and at the same time show a preferential damage of malignant tumor tissues; these effects of MRT have now been extensively studied over nearly two decades. More recently, some biological in vivo effects of synchrotron X-ray beams in the millimeter range (0.68–0.95 mm, centre-to-centre distances 1.2–4 mm), which may differ to some extent from those of microscopic beams, have been followed up to ∼7 months after irradiation. Comparisons between broad-beam irradiation and MRT indicate a higher tumor control for the same sparing of normal tissue in the latter, even if a substantial fraction of tumor cells are not receiving a radiotoxic level of radiation. The hypothesis of a selective radiovulnerability of the tumor vasculature versus normal blood vessels by MRT, and of the cellular and molecular mechanisms involved remains under investigation. The paper highlights the history of MRT including salient biological findings after microbeam irradiation with emphasis on the vascular components and the tolerance of the central nervous system. Details on experimental and theoretical dosimetry of microbeams, core issues and possible therapeutic applications of MRT are presented.

The Current Performance of the Wide Range (90-2500 eV) Soft X-ray Beamline at the Australian Synchrotron

Abstract: The Soft X‐ray beamline at the Australian synchrotron has been constructed around a collimated light Plane Grating Monochromator taking light from an Elliptically Polarized Undulator (EPU). The beamline covers a wide photon energy range between 90 to 2500 eV, using two gratings of 250 l/mm and 1200 l/mm. At present the output from the monochromator is directed into one branchline with a dedicated UHV endstation. The measured performance of the beamline in flux and resolution is shown to be very close to that of theoretical calculations.

Schwinger limit attainability with extreme power lasers.

Abstract: High intensity colliding laser pulses can create abundant electron-positron pair plasma [A. R. Bell and J. G. Kirk, Phys. Rev. Lett. 101, 200403 (2008)], which can scatter the incoming electromagnetic waves. This process can prevent one from reaching the critical field of quantum electrodynamics at which vacuum breakdown and polarization occur. Considering the pairs are seeded by the Schwinger mechanism, it is shown that the effects of radiation friction and the electron-positron avalanche development in vacuum depend on the electromagnetic wave polarization. For circularly polarized colliding pulses, these effects dominate not only the particle motion but also the evolution of the pulses. For linearly polarized pulses, these effects are not as strong. There is an apparent analogy of these cases with circular and linear electron accelerators to the corresponding constraining and reduced roles of synchrotron radiation losses.

Enhanced relativistic harmonics by electron nanobunching

Abstract: It is shown that when an few-cycle, relativistically intense, p-polarized laser pulse is obliquely incident on overdense plasma, the surface electrons may form ultra-thin, highly compressed layers, with a width of a few nanometers. These electron "nanobunches" emit synchrotron radiation coherently. We calculate the one-dimensional synchrotron spectrum analytically and obtain a slowly decaying power-law with an exponent of 4/3 or 6/5. This is much flatter than the 8/3 power of the BGP (Baeva-Gordienko-Pukhov) spectrum, produced by a relativistically oscillating bulk skin layer. The synchrotron spectrum cut-off frequency is defined either by the electron relativistic $\gamma$-factor, or by the thickness of the emitting layer. In the numerically demonstrated, locally optimal case, the radiation is emitted in the form of a single attosecond pulse, which contains almost the entire energy of the full optical cycle.

Synchrotron radiation by fast fermions in heavy-ion collisions

Abstract: We study the synchrotron radiation of gluons by fast quarks in strong magnetic field produced by colliding relativistic heavy ions. We argue that due to high electric conductivity of plasma, the magnetic field is almost constant during the entire plasma lifetime. We calculate the energy loss due to synchrotron radiation of gluons by fast quarks. We find that the typical energy loss per unit length for a light quark at the Large Hadron Collider is a few GeV per fm. This effect alone predicts quenching of jets with ${p}_{\ensuremath{\perp}}$ up to about 20 GeV. We also show that the spin-flip transition effect accompanying the synchrotron radiation leads to a strong polarization of quarks and leptons with respect to the direction of the magnetic field. Observation of the lepton polarization may provide a direct evidence of existence of strong magnetic field in heavy-ion collisions.

Enhanced relativistic harmonics by electron nanobunching

Abstract: It is shown that when a few-cycle, relativistically intense, p-polarized laser pulse is obliquely incident on overdense plasma, the surface electrons may form ultrathin, highly compressed layers with a width of a few nanometers. These electron “nanobunches” emit synchrotron radiation coherently. We calculate the one-dimensional synchrotron spectrum analytically and obtain a slowly decaying power law with an exponent of 4/3 or 6/5. This is much flatter than the 8/3 power of the Baeva–Gordienko–Pukhov spectrum, produced by a relativistically oscillating bulk skin layer. The synchrotron spectrum cutoff frequency is defined either by the electron relativistic γ-factor or by the thickness of the emitting layer. In the numerically demonstrated, locally optimal case, the radiation is emitted in the form of a single attosecond pulse, which contains almost the entire energy of the full optical cycle.

Diffraction Radiation from Relativistic Particles

Abstract: Foreword Preface 1. Radiation from Relativistic Particles 2. General Properties of Diffraction Radiation 3. Diffraction Radiation at Optical and Lower Frequencies 4. Diffraction Radiation in the Ultraviolet and Soft X-Ray Regions 5. Diffraction Radiation at the Resonant Frequency 6. Diffraction Radiation from Media with Periodic Surfaces 7. Coherent Radiation Generated by Bunches of Charged Particles 8. Diffraction Radiation in the Pre-Wave (FRESNEL) Zone 9. Experimental Investigations of Diffraction Radiation Generated by Relativistic Electrons References

Evidence for a compact jet dominating the broad-band spectrum of the black hole accretor XTE J1550–564

Abstract: The black hole X-ray binary XTE J1550-564 was monitored extensively at X-ray, optical and infrared wavelengths throughout its outburst in 2000. We show that it is possible to separate the optical/near-infrared (OIR) jet emission from the OIR disc emission. Focussing on the jet component, we find that as the source fades in the X-ray hard state, the OIR jet emission has a spectral index consistent with optically thin synchrotron emission (alpha approximate to -0.6 to -0.7, where F-v proportional to v(alpha)). This jet emission is tightly and linearly correlated with the X-ray flux; L-OIR,L-jet proportional to L-X(0.98 +/- 0.08) suggesting a common origin. This is supported by the OIR, X-ray and OIR toX-ray spectral indices being consistent with a single power law (alpha=-0.73). Ostensibly the compact synchrotron jet could therefore account for similar to 100 per cent of the X-ray flux at low luminosities in the hard state. At the same time, (i) an excess is seen over the exponential decay of the X-ray flux at the point in which the jet would start to dominate, (ii) the X-ray spectrum slightly softens, which seems to be due to a high-energy cut-off or break shifting to a lower energy and (iii) the X-ray rms variability increases. This may be the strongest evidence to date of synchrotron emission from the compact, steady jet dominating the X-ray flux of an X-ray binary. For XTE J1550-564, this is likely to occur within the luminosity range similar to(2 x 10(-4)-2 x 10(-3)) L-Edd on the hard-state decline of this outburst. However, on the hardstate rise of the outburst and initially on the hard-state decline, the synchrotron jet can only provide a small fraction (similar to a few per cent) of the X-ray flux. Both thermal Comptonization and the synchrotron jet can therefore produce the hard X-ray power law in accreting black holes. In addition, we report a phenomenological change in the OIR spectral index of the compact jet from possibly a thermal distribution of particles to one typical of optically thin synchrotron emission, as the jet increases in energy over these similar to 20 d. Once the steady jet is fully formed and the infrared and X-ray fluxes are linearly correlated, the spectral index does not vary (maintaining alpha =-0.7) while the luminosity decreases by a factor of 10. These quantitative results provide unique insights into the physics of the relativistic jet acceleration process.

Synchrotron radiation in strongly coupled conformal field theories

Abstract: Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled $\mathcal{N}=4$ supersymmetric Yang-Mills theory. We compare the strong coupling results to those at weak coupling, finding them to be very similar. In both regimes, the angular distribution of the radiated power is in fact similar to that of synchrotron radiation produced by an electron in circular motion in classical electrodynamics: the quark emits radiation in a narrow beam along its velocity vector with a characteristic opening angle $\ensuremath{\alpha}\ensuremath{\sim}1/\ensuremath{\gamma}$. To an observer far away from the quark, the emitted radiation appears as a short periodic burst, just like the light from a lighthouse does to a ship at sea. Our strong coupling results are valid for any strongly coupled conformal field theory with a dual classical gravity description.

Application of Zero-Bias Quasi-Optical Schottky-Diode Detectors for Monitoring Short-Pulse and Weak Terahertz Radiation

Abstract: Schottky diodes are well-known nonlinear elements allowing for effective detection and mixing of electromagnetic radiation in the range through microwave to terahertz. Although less sensitive than their superconducting counterparts, they generally do not require cooling that makes them the devices of choice for applications where the ultimate sensitivity is not needed. In the emerging field of terahertz technology, there is a long-time quest for cheap and handy detectors for laboratory use, as well as for serial compact and midsize instruments. We describe the use of a quasi-optically coupled zero-bias planar Schottky-diode detector for monitoring picosecond pulses of synchrotron terahertz radiation and weak continuous-wave emission from an array of Josephson junctions.

Relativistic Doppler-boosted emission in gamma-ray binaries

Abstract: Context. Gamma-ray binaries could be compact pulsar wind nebulae formed when a young pulsar orbits a massive star. The pulsar wind is contained by the stellar wind of the O or Be companion, creating a relativistic comet-like structure accompanying the pulsar along its orbit.Aims. The X-ray and the very high energy (> 100 GeV, VHE) gamma-ray emission from the binary LS 5039 are modulated on the orbital period of the system. Maximum and minimum flux occur at the conjunctions of the orbit, suggesting that the explanation is linked to the orbital geometry. The VHE modulation has been proposed to be due to the combined effect of Compton scattering and pair production on stellar photons, both of which depend on orbital phase. The X-ray modulation could be due to relativistic Doppler boosting in the comet tail where both the X-ray and VHE photons would be emitted.Methods. Relativistic aberrations change the seed stellar photon flux in the comoving frame so Doppler boosting affects synchrotron and inverse Compton emission differently. The dependence with orbital phase of relativistic Doppler-boosted (isotropic) synchrotron and (anisotropic) inverse Compton emission is calculated, assuming that the flow is oriented radially away from the star (LS 5039) or tangentially to the orbit (LS I +61303, PSR B1259-63).Results. Doppler boosting of the synchrotron emission in LS 5039 produces a lightcurve whose shape corresponds to the X-ray modulation. The observations imply an outflow velocity of 0.15–0.33c consistent with the expected flow speed at the pulsar wind termination shock. In LS I +61303, the calculated Doppler boosted emission peaks in phase with the observed VHE and X-ray maximum.Conclusions. Doppler boosting is not negligible in gamma-ray binaries, even for mildly relativistic speeds. The boosted modulation reproduces the X-ray modulation in LS 5039 and could also provide an explanation for the puzzling phasing of the VHE peak in LS I +61303.

A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV.

Abstract: A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector.

Threshold photoelectron spectroscopy of the methyl radical isotopomers, CH3, CH2D, CHD2 and CD3: synergy between VUV synchrotron radiation experiments and explicitly correlated coupled cluster calculations.

Abstract: Threshold photoelectron spectra (TPES) of the isotopomers of the methyl radical (CH3, CH2D, CHD2, and CD3) have been recorded in the 9.5−10.5 eV VUV photon energy range using third generation synchrotron radiation to investigate the vibrational spectroscopy of the corresponding cations at a 7−11 meV resolution. A threshold photoelectron−photoion coincidence (TPEPICO) spectrometer based on velocity map imaging and Wiley−McLaren time-of-flight has been used to simultaneously record the TPES of several radical species produced in a Ar-seeded beam by dc flash-pyrolysis of nitromethane (CHxDyNO2, x + y = 3). Vibrational bands belonging to the symmetric stretching and out-of-plane bending modes have been observed and P, Q, and R branches have been identified in the analysis of the rotational profiles. Vibrational configuration interaction (VCI), in conjunction with near-equilibrium potential energy surfaces calculated by the explicitly correlated coupled cluster method CCSD(T*)-F12a, is used to calculate vibrat...

Double core hole creation and subsequent Auger decay in NH3 and CH4 molecules.

Abstract: Energies of the hollow molecules CH42+ and NH32+ with double vacancies in the 1s shells have been measured using an efficient coincidence technique combined with synchrotron radiation. The energies ...

A compact pulsar wind nebula model of the γ-ray-loud binary LS I +61○303

Abstract: We study a model of LS I +61°303 in which its radio to TeV emission is due to interaction of a relativistic wind from a young pulsar with the wind from its companion Be star. The detailed structure of the stellar wind plays a critical role in explaining the properties of the system. We assume the fast polar wind is clumpy, which is typical for radiatively driven winds. The clumpiness and some plasma instabilities cause the two winds to mix. The relativistic electrons from the pulsar wind are retained in the moving clumps by inhomogeneities of the magnetic field, which explains the X-ray variability observed on time-scales much shorter than the orbital period. We calculate detailed inhomogeneous spectral models reproducing the average broad-band spectrum from radio to TeV Given the uncertainties on the magnetic field within the wind and the form of the distribution of relativistic electrons, the X-ray spectrum could be dominated by either Compton or synchrotron emission. The recent Fermi observations constrain the high-energy cut-off in the electron distribution to be at the Lorentz factor of 2 x 10 4 or ∼ 10 8 in the former and latter model, respectively. We provide formulae comparing the losses of the relativistic electrons due to Compton, synchrotron and Coulomb processes versus the distance from the Be star. We calculate the optical depth of the wind to free-free absorption, showing that it will suppress most of the radio emission within the orbit, including the pulsed signal of the rotating neutron star. We point out the importance of Compton and Coulomb heating of the stellar wind within and around the y -ray emitting region. Then, we find the most likely mechanism explaining the orbital modulation at TeV energies is anisotropy of emission, with relativistic electrons accelerated along the surface of equal ram pressure of the two winds. Pair absorption of the TeV emission suppresses one of the two maxima expected in an orbit.

Comparative study of multilayers used in monochromators for synchrotron-based coherent hard X-ray imaging

Abstract: A systematic study is presented in which multilayers of different composition (W/Si, Mo/Si, Pd/B(4)C), periodicity (from 2.5 to 5.5 nm) and number of layers have been characterized. In particular, the intrinsic quality (roughness and reflectivity) as well as the performance (homogeneity and coherence of the outgoing beam) as a monochromator for synchrotron radiation hard X-ray micro-imaging are investigated. The results indicate that the material composition is the dominating factor for the performance. By helping scientists and engineers specify the design parameters of multilayer monochromators, these results can contribute to a better exploitation of the advantages of multilayer monochromators over crystal-based devices; i.e. larger spectral bandwidth and high photon flux density, which are particularly useful for synchrotron-based micro-radiography and -tomography.

TEMPO: a New Insertion Device Beamline at SOLEIL for Time Resolved Photoelectron Spectroscopy Experiments on Solids and Interfaces

Abstract: A new insertion device beamline is now operational on straight section 8 at the SOLEIL synchrotron radiation source in France. The beamline and the experimental station were developed to optimize the study of the dynamics of electronic and magnetic properties of materials. Here we present the main technical characteristics of the installation and the general principles behind them. The source is composed of two APPLE II type insertion devices. The monochromator with plane gratings and spherical mirrors is working in the energy range 40–1500 eV. It is equipped with VLS, VGD gratings to allow the user optimization of flux or higher harmonics rejection. The observed resonance structures measured in gas phase enable us to determine the available energy resolution: a resolving power higher than 10000 is obtained at the Ar 2p, N 1s and Ne K‐edges when using all the optical elements at full aperture. The total flux as a function of the measured photon energy and the characterization of the focal spot size complete the beamline characterization.

Performance of the AILES THz-Infrared beamline at SOLEIL for High resolution spectroscopy

Abstract: The new THz beamline (AILES) located at the third generation Synchrotron Radiation source SOLEIL is now operating for applications in a wide variety of research themes. In particular, this source with its adapted optics allows high resolution spectroscopic measurements of molecules in the entire infrared and THz range. This presentation focuses on the performances concerning flux, spectral range and stability for molecular spectroscopy. Thanks to these performances, the coupling of synchrotron radiation from a highly stable third generation source with high resolution FTIR spectrometer and with a long path cell (150 m or more) can be particularly advantageous. This fact is related to the optics of the beamline permitting the entire source to be used without aperture stop (entrance iris), even for measurements at highest‐resolution of ∼0.1 μeV (10−3 cm−1).

Nonproportional Response Between 0.1–100 keV Energy by Means of Highly Monochromatic Synchrotron X-Rays

Abstract: Using highly monochromatic X-ray synchrotron radiation ranging from 9 keV to 100 keV, accurate Lu2Si2O7:Ce3+,Ca (LSO), Lu3Al5O:Pr3+ (LuAG), Lu2Si2O5:Ce3+ (LPS) and Gd2SiO5:Ce3+ (GSO) nonproportional response curves were determined. By utilizing information from escape peaks in pulse height spectra the response curve can be extended down to several keV. A detailed study of the nonproportionality just above the if-edge is presented and from that a method, which we named K-dip spectroscopy, is obtained to reconstruct the electron response curve down to energies as low as 100 eV.

Synchrotron Radiation from Ultra-High Energy Protons and the Fermi Observations of GRB 080916C

Abstract: Fermi ! -ray telescope data of GRB 080916C with ~10 55 erg in apparent isotropic ! -ray energy, show a several second delay between the rise of 100 MeV - GeV radiation compared with keV - MeV radiation. Here we show that synchrotron radiation from cosmic ray protons accelerated in GRBs, delayed by the proton synchrotron cooling timescale in a jet of magnetically-dominated shocked plasma moving at highly relativistic speeds with bulk Lorentz factor !~500 , could explain this result. A second generation electron synchrotron component from attenuated proton synchrotron radiation makes enhanced soft X-ray to MeV ! -ray emission. Long GRBs with narrow, energetic jets accelerating particles to ultra-high energies could explain the Auger observations of UHE cosmic rays from sources within 100 Mpc for nano-Gauss intergalactic magnetic fields. The total energy requirements in a proton synchrotron model are !" 16/3 . This model for GRB 080916C is only plausible if Γ< ~ 500 and the jet opening angle is ~1 o .

On the possibilities of hard X-ray imaging with high spatio-temporal resolution using polychromatic synchrotron radiation.

Abstract: Time-resolved imaging with penetrating radiation has an outstanding scientific value but its realisation requires a high density of photons as well as corresponding fast X-ray image detection schemes. Bending magnets and insertion devices of third generation synchrotron light sources offer a polyc hromatic photon flux density which is high enough to perform h ard X-ray imaging with a spatio-temporal resolution up to the µm-µs range. Existing indirect X-ray image detectors commonly used at synchrotron light sources can be adapted for fast image acquisition by employing CMOS-based digital high speed cameras already available on the market. Selected applications from life sciences and materials research underline the high potential of this high-speed hard X-ray microimaging approach.

Plant‐based food and feed protein structure changes induced by gene‐transformation, heating and bio‐ethanol processing: A synchrotron‐based molecular structure and nutrition research program

Abstract: Unlike traditional "wet" analytical methods which during processing for analysis often result in destruction or alteration of the intrinsic protein structures, advanced synchrotron radiation-based Fourier transform infrared microspectroscopy has been developed as a rapid and nondestructive and bioanalytical technique. This cutting-edge synchrotron-based bioanalytical technology, taking advantages of synchrotron light brightness (million times brighter than sun), is capable of exploring the molecular chemistry or structure of a biological tissue without destruction inherent structures at ultra-spatial resolutions. In this article, a novel approach is introduced to show the potential of the advanced synchrotron-based analytical technology, which can be used to study plant-based food or feed protein molecular structure in relation to nutrient utilization and availability. Recent progress was reported on using synchrotron-based bioanalytical technique synchrotron radiation-based Fourier transform infrared microspectroscopy and diffused reflectance infrared Fourier transform spectroscopy to detect the effects of gene-transformation (Application 1), autoclaving (Application 2), and bio-ethanol processing (Application 3) on plant-based food and feed protein structure changes on a molecular basis. The synchrotron-based technology provides a new approach for plant-based protein structure research at ultra-spatial resolutions at cellular and molecular levels.

Recent applications and current trends in analytical chemistry using synchrotron-based Fourier-transform infrared microspectroscopy

Abstract: Synchrotron radiation based Fourier-transform infrared (SR-FTIR) microspectroscopy is an emerging technique, which is increasingly employed in analytical sciences. This technique combines FTIR spectroscopy (namely specific identification of molecular groups within a variety of environments: organic/inorganic, crystallized/amorphous, solid/liquid/gas) with high brightness, and therefore small spot size and faster acquisition of high-quality spectral imaging data from a synchrotron light source. In this article, we review several recent applications of SR-FTIR that have led to much of the improved analytical capabilities. Performing analytical science at large-scale facilities allows one to access state-of-the-art equipment and capabilities, receive expert assistance from the facility staff, and have the possibility of combining SR-FTIR microscopy with other synchrotron-based X-ray microimaging techniques.