Flash X-ray Research Articles

A quark nova in the wake of a core-collapse supernova: a unifying model for long duration gamma-ray bursts and fast radio bursts

By appealing to a quark nova (QN; the explosive transition of a neutron star to a quark star) in the wake of a core-collapse supernova (CCSN) explosion of a massive star, we develop a unified model for long duration gamma-ray bursts (LGRBs) and fast radio bursts (FRBs). The time delay (years to decades) between the SN and the QN, and the fragmented nature (i.e., millions of chunks) of the relativistic QN ejecta are key to yielding a robust LGRB engine. In our model, an LGRB light curve exhibits the interaction of the fragmented QN ejecta with turbulent (i.e., filamentary and magnetically saturated) SN ejecta which is shaped by its interaction with an underlying pulsar wind nebula (PWN). The afterglow is due to the interaction of the QN chunks, exiting the SN ejecta, with the surrounding medium. Our model can fit BAT/XRT prompt and afterglow light curves simultaneously with their spectra, thus yielding the observed properties of LGRBs (e.g., the Band function and the X-ray flares). We find that the peak luminositypeak photon energy relationship (i.e., the Yonetoku law), and the isotropic energy-peak photon energy relationship (i.e., the Amati law) are not fundamental but phenomenological. FRB-like emission in our model results from coherent synchrotron emission (CSE) when the QN chunks interact with non-turbulent weakly magnetized PWN-SN ejecta, where conditions are prone to the Weibel instability. Magnetic field amplification induced by the Weibel instability in the shocked chunk frame sets the bunching length for electrons and pairs to radiate coherently. The resulting emission frequency, luminosity and duration in our model are consistent with FRB data. We find a natural unification of high-energy burst phenomena from FRBs (i.e., those connected to CCSNe) to LGRBs including X-ray flashes (XRFs) and X-ray rich GRBs (XRR-GRBs) as well as superluminous SNe (SLSNe). We find a possible connection between ultra-high energy cosmic rays and FRBs and propose that a QN following a binary neutron star merger can yield a short duration GRB (SGRB) with fits to BAT/XRT light curves.

The energy distribution characteristics of a cylindrical cased charge with two end caps

The energy distribution characteristics are the key parameters for analysing the energy distribution of the cylindrical cased charge and improving the damage efficiency of the warhead. To investigate the initial velocities from a cylindrical cased charge detonated at the point on the axis, the flash X-ray radiography system was used to test the velocities of the end caps, and the influence of the axial position of the detonation point was further studied by simulation. The experimental results show that when the thickness of the end cap is equal to that of the casing and the ratio of length to diameter is 3, the velocity of the front end cap is 0.53 times that of the rear end cap. The simulation results show that the initial velocities and energy distribution are affected by the height from the detonation point to the end, and the conversion efficiency of the explosive energy can be increased by adjusting the detonation height and the charge length.

Deformation and acceleration of Zn and Cu liners under explosive shock loading

Both zinc and copper shaped charge jets (SCJs) generated from conical liners under explosive shock loading were observed using soft flash x-ray radiography. The goal was to ascertain the effect of the liner material melting point on the jet features and density. An analytical method termed in situ mass analysis from x-ray image processing (i-MAX) was utilized to estimate the mass and apparent density of each SCJ in this study. The masses determined for the zinc and copper leading jets were (34 ± 2) mg and (68 ± 3) mg, respectively. The overall mass distributions of both the zinc and copper SCJs showed the same tendency to decrease toward the tip of the jet, with the exception of the leading jet. The density distribution of the zinc SCJ gradually decreased toward the leading jet as it stretched. In contrast, the density distribution of the copper SCJ varied depending on the appearance of a necking region, and the minimum apparent density was observed 30 mm from the leading jet. These results demonstrate that the occurring of cavitation or vacancy avalanches in metal jet depend on the melting point of the liner material.

Radiation effects in alpha-doped UO2

UO2 samples doped with the strong α-emitter 238Pu were periodically characterised to study the potential effects of α-self-irradiation on spent nuclear fuel during storage. The degradation of the thermal properties and microstructure of the samples were monitored using the Laser Flash technique (LAF), X-Ray Diffraction (XRD), and Scanning and Transmission Electron Microscopy (SEM, TEM). The thermal conductivity decreased with a non-linear behaviour as a function of the α-dose. Three clearly different stages in the thermal conductivity degradation could be detected, and saturation was reached at relatively low doses (0.035 dpa). In combination with analyses of the microstrain measured by XRD, and TEM images, these three phases could be attributed to three stages of radiation-induced defect generation and clustering. SEM inspection showed the thermal conductivity degradation cannot be due to loss of integrity or grain boundary opening. The radiation damage produced resulted in the formation of dislocation loops as observed by TEM.

Ballistic research techniques: visualizing gunshot wounding patterns

There are difficulties associated with mapping gunshot wound (GSW) patterns within opaque models. Depending on the damage measurement parameters required, there are multiple techniques that can provide methods of “seeing” the GSW pattern within an opaque model. The aim of this paper was to test several of these techniques within a cadaveric animal limb model to determine the most effective. The techniques of interest were flash X-ray, ultrasound, physical dissection, and computed-tomography (CT). Fallow deer hind limbs were chosen for the model with four limbs used for each technique tested. Quarantined 7.62 × 39 mm ammunition was used for each shot, and each limb was only shot once, on an outdoor range with shots impacting at muzzle velocity. Flash X-ray provided evidence of yaw within the limb during the projectile’s flight; ultrasound though able to visualise the GSW track, was too subjective and was abandoned; dissection proved too unreliable due to the tissue being cadaveric so also too subjective; and lastly, CT with contrast provided excellent imaging in multiple viewing planes and 3D image reconstruction; this allowed versatile measurement of the GSW pattern to collect dimensions of damage as required. Of the different techniques examined in this study, CT with contrast proved the most effective to allow precise GSW pattern analysis within a cadaveric animal limb model. These findings may be beneficial to others wishing to undertake further ballistic study both within clinical and forensic fields.

Systematic Study of the Peak Energy of Broadband Gamma-Ray Burst Spectra

Abstract We have performed a systematic study of gamma-ray bursts (GRBs), which have various values in the peak energy of the νF ν spectrum of prompt emission, E peak, observed by the Swift/Burst Alert Telescope (BAT) and Fermi/Gamma-ray Burst Monitor, investigating their prompt and X-ray afterglow emissions. We cataloged long-lasting GRBs observed by Swift between 2004 December and 2014 February in three categories according to the classification by Sakamoto et al.: X-ray flashes (XRFs), X-ray-rich GRBs (XRRs), and classical GRBs (C-GRBs). We then derived , as well as if viable, of the Swift spectra of their prompt emission. We also analyzed their X-ray afterglows and found that GRB events with a lower , i.e., softer GRBs, are fainter in 0.3–10 keV X-ray luminosity and decay more slowly than harder GRBs. The intrinsic event rates of the XRFs, XRRs, and C-GRBs were calculated using the Swift/BAT trigger algorithm. Those of the XRRs and XRFs are larger than that of the C-GRBs. If we assume that the observational diversity of E peak is explained using the off-axis model, these results yield a jet half-opening angle of Δθ ∼ 0.°3, and a variance of the observing angles θ obs ≲ 0.°6. This implies that this tiny variance would be responsible for the E peak diversity observed by Swift/BAT, which is unrealistic. Therefore, we conclude that the E peak diversity is not explained with the off-axis model, but is likely to originate from some intrinsic properties of the jets.

Investigation the Effect of Soft X-ray Flash Exposure on PN Diode

In this paper will present the properties of PN diode before and after expose by radiation. Although, radiation help to improve the performance of semiconductor device but still has some damage in device structure. In previous article I have showed performance improve after expose by soft radiation. The device is exposed by low frequency X-ray radiation (soft radiation flash exposure: SRFE) technique with few second for several times. In principle of PN diode after fabrication will has defects from process such as ion implantation, doped and silicon wafer process. The results show temperature while SRFE expose on device that generate high temperature on surface and silicon boundary that may the optimize energy and expose time for treatment damage of PN diode.

A Review of Shaped Charge Variables for its Optimum Performance

Shaped charge is a device for focusing the chemical energy of explosives to a particular point or line for penetration or cutting purpose respectively. They are used for the penetration or cutting of various types of targets on land, water, underground, underwater, or air. Their shape is either conical or linear and consists of explosive, casing and liner. The liner is bent towards the central axis producing a thin hypervelocity jet by the energy released as a result of the explosive detonation. This jet is utilized against the target. Shaped charges can perforate or penetrate targets like aircrafts, ships, submarines, armored vehicles, battle tanks, and bunkers. This paper presents a detailed review of analytical works, computer simulations, and experimental results related to the liner. Among modern diagnostic techniques flash x-rays, radiography is most used in the experiments performed in the last 40 years. Powder metallurgy, which started in the late twentieth century raised the efficiency of shaped charges to new altitudes. The efficiency of the shaped charge depends on numerous factors such as explosive’s type, liner’s material, geometry and metallurgy, manufacturing technique, and casing thickness. Factors concerning the liner’s material, metallurgical advancements, and geometry are discussed chronologically and in detail.

Design of bremsstrahlung target of 4 MeV flash X-ray machine

Bremsstrahlung converter target is one of the key factors for flash X-ray machine. The bremsstrahlung radiation process in which the electron beam impinges on the target is simulated utilizing the Monte Carlo method, by which the influence of the effective target thickness on the exposure is analyzed, the optimal target thickness and the exposure are also obtained for the 4 MeV flash X-ray machine. The damages of target impacted by the electron beam are compared and discussed for various electron energy deposit density from different sources, such as 12 MeV LIA, Dragon accelerators and 4 MeV flash X-ray machine. The results show that the tantalum distributed target may be the satisfactory solution for the bremsstrahlung target of 4 MeV flash X-ray machine.

Technique for inferring angle change as a function of time for high-current electron beams using a dose-rate monitor array.

Intense electron beams striking a high-atomic number target produce high-output pulsed photon fluxes for flash x-ray experiments. Without an external guide field, such beams are subject to the dynamics of high-current electron beam propagation, including changes to electron trajectories either from self-fields or from development of beam instabilities. The bremsstrahlung output (dose-rate) scales approximately as IVx, where I is the beam current, V the electron energy, and x is in the range 2.0-2.65 and depends upon the electron angle on the converter. Using experimental beam data (dose-rate, I and V), this equation can be solved for x, a process known as "inverting the radiographer's equation." Inversion methods that rely on thermoluminescent dosimeters, which are time-integrated, yield no information about evolution of the electron beam angle in time. We propose here an inversion method that uses several dose-rate monitors at different angles with respect to the beam axis. By measuring dose-rates at different angles, one can infer the time-dependent beam voltage and angle. This method compares well with estimates of corrected voltage and results in a self-consistent picture of beam dynamics. Techniques are demonstrated using data from self-magnetic pinch experiments at the RITS-6 facility at Sandia National Laboratories.

Development of a 4-MV, 80-kA-Induction Voltage Adder for Flash X-ray Radiography

An induction voltage adder (IVA) has been developed to drive rod-pinch diodes (RPDs), to produce X-rays for flash radiography. The IVA facility consists of four-stage induction cavities stacked in series, each of which is single-point driven by a 6- $\Omega $ pulseline. The prime pulsed-power source comprises two Marx generators and four de-ionized water pulselines. Each Marx generator fast charges two pulselines to about 2.2 MV in less than 370 ns. Four electrically triggered, SF6-insulated gas switches serve as energy-transfer switches from pulse-forming lines to output transmission lines, and thus without an additional intermediate energy storage. A stepped inner stalk is utilized to make the vacuum impedance of the secondary transmission line increase from $30~\Omega $ at the first cavity to $120~\Omega $ at the last cavity, to prevent the electron emission from cathode surfaces. The RPD is chosen to create bremsstrahlung X-rays, which are believed to be optimal at voltage levels of about 4 MV. In this article, the design details and experimental results concerning the main components, such as the Marx/PFLs, IVA, and RPD, are demonstrated. The electrical performances of the facility are characterized. Presently, the IVA provides voltages of up to 4.3 MV and currents of up to 85 kA. The X-ray dose is up to 15.5 Rad [lithium fluoride (LiF)] at 1 m with a spot size of 1.4 mm and a FWHM time of 55 ns.

Fast Extragalactic X-Ray Transients from Gamma-Ray Bursts Viewed Far Off-axis

Abstract The observed light curves and estimated sky rate of fast extragalactic X-ray transients (XRTs) discovered in archival Chandra data indicate that they belong to two distinct XRT populations. The first population of relatively short duration pulses, which typically last less than few minutes seems to be pulses of X-ray flashes, which are nearby long-duration gamma-ray bursts viewed from far off-axis. The second population of much longer pulses, which typically last hours, seems to be the early-time isotropic afterglows of short gamma-ray bursts that are beamed away from Earth, as was shown in a previous paper.

Influence of microstructure on the impact failure of alumina

In this paper, we detail a study involving the characterization of two grades of alumina (CoorsTek Engineered Ceramics AD-85 and AD-995) and subsequent impact experiments with tungsten carbide spheres at 400 m/s. Through this work, we hope to understand the relationship between microstructure and the high strain rate behaviors of advanced ceramics. Initial characterization of microstructure with scanning electron microscopy, electron backscatter diffraction, and energy dispersive X-ray spectroscopy determined grain size, and the elemental character of the materials and the inclusions present. AD-85 alumina was found to have smaller alumina grains and more non-alumina inclusions than AD-995 alumina. Compression testing with in-situ visualization for crack speeds demonstrated that the strength of AD-85 increased from 2.0 ± 0.1 GPa at 10-3 s-1 to 2.7 ± 0.3 GPa at 500 s-1 (crack speeds of 1800 ± 600 m/s). The AD-995 had strength increases of 2.4 ± 0.2 GPa at 10-3 s-1 to 3.6 ± 0.5 GPa at 500 s-1 (crack speeds of 2200 ± 400 m/s). The greater rate sensitivity and higher crack speed of the AD-995 is related to microstructure and mechanical properties. Impact experiments used spherical tungsten carbide projectiles fired from a smoothbore powder gun into alumina discs held in place with polycarbonate holders that provided no lateral confinement and minimal back face confinement. The use of simultaneous high-speed video, photon-doppler velocimetry, and flash X-ray during these impact experiments produced information on the cracking and microbending of the target in the first 10 μs of impact, with a number of significant events happening within the first 5 μs. At 400 m/s, AD-85 alumina suffered penetration by the projectile while AD-995 alumina defeated the projectile. The data allows for comparison of event timing such as peak back face velocity and the onset of radial cracking, demonstrating that during an impact event, interface defeat occurs within the first 5 μs. The data collected and analysis done also suggests that the failure of the projectile can couple with the target via the transmission of shear waves and contribute to failure, which has implications for future modelling and design of improved protection systems.

GRB X-Ray Flare Properties among Different GRB Subclasses

Abstract Gamma-ray bursts (GRBs) can be divided into three subclasses: X-ray flash (XRF), X-ray rich (XRR), and classical GRB (C-GRB). An X-ray flare is the rebrightening emission shown in the early X-ray afterglow of some GRBs. In this paper, we comprehensively examine the X-ray flare properties among XRF, XRR, and C-GRB subclasses. We utilize the XRF, XRR, and C-GRB subclass samples obtained from the Swift-BAT3 catalog, and the X-ray flare observational properties are collected from Falcone et al., Chincarini et al., and Yi et al. We find that XRFs and XRRs have more bright X-ray flares than C-GRBs. The ratio of the X-ray flare fluence to the prompt emission fluence has different distributions between XRF and C-GRB subclasses. The linear correlation between the duration and the peak time of the X-ray flares is also different between XRF and C-GRB subclasses. We are inclined to identify the GRBs with the bright X-ray flares as XRFs or XRRs. We discuss some issues that are related to the XRF/XRR/C-GRB classification. We also caution the selection effects and the instrument bias in our investigation. Large samples are required in the future to further confirm our results.

Study of pure and mixed clustered noble gas puffs irradiated with a high intensity (7 × 1019 W/cm2) sub-ps laser beam and achievement of a strong X-ray flash in a laser-generated debris-free X-ray source

AbstractWe present a broad study of linear, clustered, noble gas puffs irradiated with the frequency doubled (527 nm) Titan laser at Lawrence Livermore National Laboratory. Pure Ar, Kr, and Xe clustered gas puffs, as well as two mixed-gas puffs consisting of KrAr and XeKrAr gases, make up the targets. Characterization experiments to determine gas-puff density show that varying the experimental parameter gas-delay timing (the delay between gas puff initialization and laser-gas-puff interaction) provides a simple control over the gas-puff density. X-ray emission (>1.4 keV) is studied as a function of gas composition, density, and delay timing. Xe gas puffs produce the strongest peak radiation in the several keV spectral region. The emitted radiation was found to be anisotropic, with smaller X-ray flux observed in the direction perpendicular to both laser beam propagation and polarization directions. The degree of anisotropy is independent of gas target type but increases with photon energy. X-ray spectroscopic measurements estimate plasma parameters and highlight their difference with previous studies. Electron beams with energy in excess of 72 keV are present in the noble gas-puff plasmas and results indicate that Ar plays a key role in their production. A drastic increase in harder X-ray emissions (X-ray flash effect) and multi-MeV electron-beam generation from Xe gas-puff plasma occurred when the laser beam was focused on the front edge of the linear gas puff.

A comparison of the ballistic behaviour of conventionally sintered and additively manufactured alumina

Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages. However, even assuming that such technologies could be successfully deployed in the field, such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics. In this study, the ballistic performance of a series of additively manufactured (AM)/rapidly-prototyped (RP) alumina tiles of 97.2% of the density of Sintox FA™ were investigated using both forward- and reverse-ballistic experiments. These experiments, undertaken with compressed gas-guns, employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction, respectively. The RP alumina was found to exhibit useful ballistic properties, successfully defeating steel-cored (AP) 7.62 × 39 mm BXN rounds at velocities of up-to c.a. 850 m/s, while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FA™. However, where a <1% by vol. Cu dopant was introduced into the RP material failure modes changed dramatically with performance dropping below that of conventionally sintered alumina. Overall, the results from both sets of experiments were complimentary and clearly indicated the potential of such RP materials to play an active role in provision of real-world body armour solutions provided quality control of the RP material can be maintained.

Polymorphic states and phase transitions in a comb-like polymer having a rigid polyester backbone and flexible side chains

Structure formation in an alkoxylated polyester having rigid backbone and flexible side chains composed of 10 alkyl carbons per side chain is studied using X-ray diffraction, conventional DSC and flash DSC techniques. Two crystalline states-modification B and modification A are observed with their occurrence depending on the thermal treatment. Additionally, a liquid crystalline phase is also detected above the melting temperature of modification A. While modification B is the thermodynamically preferred phase at low temperatures consisting of crystalline side chains, modification A is observed on heating above 120 °C and shows a disordered packing of the side chains. Rapid cooling using Fast Differential Scanning Calorimetry (FDSC) yields a liquid crystalline state wherein a long range ordered layered morphology exists, however, the π − π stacking of the backbones is absent. The molecular orientation of backbones under the influence of shear fields as well as on a glass fiber surface is also studied. Both modifications A and B show backbone orientation along the shear fields in an extruded sample while a preferential edge-on orientation is inferred on the glass fiber surface.

Investigation on the spatial distribution characteristics of behind-armor debris formed by the perforation of EFP through steel target

Abstract The behind-armor debris (BAD) formed by the perforation of an EFP is the main damage factor for the secondary destruction to the behind-armor components. Aiming at investigating the BAD caused by EFP, flash X-ray radiography combined with an experimental witness plate test method was used, and the FEM-SPH adaptive conversion algorithm in LS-DYNA software was employed to model the perforation process. The simulation results of the debris cloud shape and number of debris were in good agreement with the flash X-ray radiographs and perforated holes on the witness plate, respectively. Three-dimensional numerical simulations of EFP's penetration under various impact conditions were conducted. The results show that, an ellipsoidal debris cloud, with the major-to-minor axis radio (a/b) smaller than that caused by shaped charge jets, was formed behind the target. With the increase of target thickness (h) and decrease of impact velocity (v0) and obliquity (θ), the value of a/b decreases. The number of debris ejected from target is significantly higher than that from EFP. Based on the statistical analysis of the spatial distribution of the BAD, An engineering calculation model was established considering the influence of h, v0 and θ. The model can with reasonable accuracy predict the quantity and velocity distribution characteristics of BAD formed by EFP.

Investigation of fragment reconstruction accuracy with in situ few-view flash x-ray high-speed computed tomography (HSCT)

Few-view in situ flash x-ray high-speed computed tomography (HSCT) is a computed tomography (CT) technique used to investigate high-speed phenomena on the timescale of microseconds. The successful application to quantitatively analyze and characterize fragments formed during a 1000 m s−1 impact process onto a ceramic plate with a CT reconstruction from only six x-ray projections has been shown. The method delivers spatially resolved 3D information about the fragments at one point in time. This information is not (or only partially) accessible by alternative experimental methods. Therefore, quantifying the accuracy of the measured data is not directly possible. In order to estimate the precision of the method and the influence of different sources limiting accuracy, a simulation study consisting of 250 virtual experiments was carried out. The border conditions of the study are based on the actual experimental data from the six-view experiment. The results show that steel fragments with a diameter of about 8 mm (volume ~ 300 mm3, weight ~ 2.5 g) can be reconstructed with an averaged relative volume deviation of about 30%. For larger framents, the error reduces down to 10% relative average deviation. The spatial position of the center of mass can be determined with an averaged uncertainty of about 0.8 to 1.2 mm for most fragment sizes.

Generation of bright γ-ray/hard x-ray flash with intense femtosecond pulses and double-layer targets

We study a method to generate collimated γ-ray/hard X-ray flash with high energy conversion efficiency and high peak brilliance by shooting a double-layer target with a readily available ultra-intense laser pulse. The target is composed of a homogeneous tens-of-micrometer-thick slightly underdense plasma (SUP) slab in front of an ultrathin foil. For optimal targets, particle-in-cell numerical simulations reveal that nonlinear Thomson scattering from directly accelerated superponderomotive electrons leads to the generation of a γ-ray flash with a peak brilliance of 1.6×1022 photons/s/mm2/0.1%BW at the MeV energy level at a laser intensity of 8.5×1020W/cm2. The dependence of the emission on the target parameters is systematically studied. Compared with using slightly overdense plasma, the use of SUP results in the enhancement of the photon number and brightness of the γ-ray flash by a factor of 10 and 40, respectively. The underlying physics of the enhancement is discussed.