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Sample records for medium energy x-rays

  1. The energy dependence of lithium formate and alanine EPR dosimeters for medium energy x rays

    SciTech Connect

    Waldeland, Einar; Hole, Eli Olaug; Sagstuen, Einar; Malinen, Eirik

    2010-07-15

    Purpose: To perform a systematic investigation of the energy dependence of alanine and lilthium formate EPR dosimeters for medium energy x rays. Methods: Lithium formate and alanine EPR dosimeters were exposed to eight different x-ray beam qualities, with nominal potentials ranging from 50 to 200 kV. Following ionometry based on standards of absorbed dose to water, the dosimeters were given two different doses of approximately 3 and 6 Gy for each radiation quality, with three dosimeters for each dose. A reference series was also irradiated to three different dose levels at a {sup 60}Co unit. The dose to water energy response, that is, the dosimeter reading per absorbed dose to water relative to that for {sup 60}Co {gamma}-rays, was estimated for each beam quality. In addition, the energy response was calculated by Monte Carlo simulations and compared to the experimental energy response. Results: The experimental energy response estimates ranged from 0.89 to 0.94 and from 0.68 to 0.90 for lithium formate and alanine, respectively. The uncertainties in the experimental energy response estimates were typically 3%. The relative effectiveness, that is, the ratio of the experimental energy response to that following Monte Carlo simulations was, on average, 0.96 and 0.94 for lithium formate and alanine, respectively. Conclusions: This work shows that lithium formate dosimeters are less dependent on x-ray energy than alanine. Furthermore, as the relative effectiveness for both lithium formate and alanine were systematically less than unity, the yield of radiation-induced radicals is decreased following x-irradiation compared to irradiation with {sup 60}Co {gamma}-rays.

  2. Relative response of the alanine dosimeter to medium energy x-rays.

    PubMed

    Anton, M; Büermann, L

    2015-08-07

    The response of the alanine dosimeter to kilovoltage x-rays with respect to the dose to water was measured, relative to the response to Co-60 radiation.Two series of x-ray qualities were investigated, one ranging from 30 kV to 100 kV tube voltage (TW series), the other one ranging from 70 kV to 280 kV (TH series). Due to the use of the water calorimeter as a primary standard, the uncertainty of the delivered dose is significantly lower than for other published data. The alanine response was measured as described in a previous publication (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The uncertainty component due to the alanine measurement and analysis is ⩽0.4%, the major part of the combined uncertainty of the relative response originates from the uncertainty of the delivered dose. The relative uncertainties of the relative response vary from ⩽2% for the TW series to ⩽1.1% for the TH series.Different from the behaviour of the alanine dosimeter for megavoltage x-rays or electrons, the relative response drops significantly from unity for Co-60 radiation to less than 64% for the TW quality with a tube voltage of 30 kV. In order to reproduce this behaviour through Monte Carlo simulations, not only the ratio of the absorbed dose to alanine to the absorbed dose to water has to be known, but also the intrinsic efficiency, i.e. the dependence of the number of free radicals generated per unit of absorbed dose on the photon energy. This quantity is not yet accessible for the TW series.For a possible use of the alanine dosimeter for kilovoltage x-rays, for example in electronic brachytherapy, users should rely on the measured data for the relative response which have become available with this publication.

  3. Free-air ionization chamber, FAC-IR-300, designed for medium energy X-ray dosimetry

    NASA Astrophysics Data System (ADS)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2017-01-01

    The primary standard for X-ray photons is based on parallel-plate free-air ionization chamber (FAC). Therefore, the Atomic Energy Organization of Iran (AEOI) is tried to design and build the free-air ionization chamber, FAC-IR-300, for low and medium energy X-ray dosimetry. The main aim of the present work is to investigate specification of the FAC-IR-300 ionization chamber and design it. FAC-IR-300 dosimeter is composed of two parallel plates, a high voltage (HV) plate and a collector plate, along with a guard electrode that surrounds the collector plate. The guard plate and the collector were separated by an air gap. For obtaining uniformity in the electric field distribution, a group of guard strips was used around the ionization chamber. These characterizations involve determining the exact dimensions of the ionization chamber by using Monte Carlo simulation and introducing correction factors.

  4. An alternative scheme of angular-dispersion analyzers for high-resolution medium-energy inelastic X-ray scattering.

    PubMed

    Huang, Xian Rong

    2011-11-01

    The development of medium-energy inelastic X-ray scattering optics with meV and sub-meV resolution has attracted considerable efforts in recent years. Meanwhile, there are also concerns or debates about the fundamental and feasibility of the involved schemes. Here the central optical component, the back-reflection angular-dispersion monochromator or analyzer, is analyzed. The results show that the multiple-beam diffraction effect together with transmission-induced absorption can noticeably reduce the diffraction efficiency, although it may not be a fatal threat. In order to improve the efficiency, a simple four-bounce analyzer is proposed that completely avoids these two adverse effects. The new scheme is illustrated to be a feasible alternative approach for developing meV- to sub-meV-resolution inelastic X-ray scattering spectroscopy.

  5. Development of observational and instrumental techniques in hard X-ray and medium energy gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Pelling, M.

    1985-01-01

    The technical activities, scientific results, related space hardware projects and personnel of the high energy astrophysics program are reported. The development of observational and instrumental techniques in hard X-ray (0.001 to 100 keV) and medium energy gamma-ray (0.1 to 10 MeV) astronomy are examined. Many of these techniques were developed explicitly for use on high altitude balloons where most of the scientific results were obtained. The extensive observational activity using balloons are tabulated. Virtually every research activity will eventually result in a major space hardware development effort.

  6. Simulation of an energy-dispersion x-ray spectrometer in the computational medium X-Energo

    SciTech Connect

    Plotnikov, R.I.; Savel`ev, S.K.; Fedorov, S.I.

    1995-01-01

    The description of the calculation part of the simulation medium X-Energo is presented. It contains mathematical models included in the medium X-Energo for the determinating major processes taking place in an X-ray spectrometer, namely, the formation of an X-ray radiation spectrum, the interaction of this radiation with filter and sample materials, and the detector response to the signal. 6 refs.

  7. Comparison of photocurrent enhancement and upset enhancement in CMOS devices in a medium-energy x-ray environment

    SciTech Connect

    Beutler, D.E.; Beezhold, W.; Browning, J.S.; Fleetwood, D.M.; Counts, N.E. ); Knott, D.P. ); Freshman, C.L.; Conners, M.P. )

    1990-08-01

    Radiation-induced upset levels in SA3001 static random access memories (SRAM's) and SA 3246 clock integrated circuits (IC's) have been measured in a medium-energy flash X-ray environment (average photon energy {approximately}100 keV) where dose-enhancing effects are very important. By comparing device responses using a non-dose-enhancing ceramic package lid and a dose-enhancing Kovar/gold lid, dose-enhancement factors for photocurrent and upset were generated. The observed upset enhancement factors of 3.0 {plus minus} 0.5 (SRAM) and 2.2 {plus minus} 0.2 (clock IC) are in excellent agreement with measurements of photocurrent enhancement factors (2.5 {plus minus} 0.5) in diodes processed with the same diffusions as the complementary metal-oxide-semiconductor (CMOS) IC's irradiated in a steady-state X-ray environment. These results indicate that upset is dominated by the radiation-induced transient supply current in these IC's, and that steady-state diode photocurrent measurements are a good predictor of both photocurrent and upset enhancement for IC's made with this technology.

  8. Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method.

    PubMed

    Grimbergen, T W; van Dijk, E; de Vries, W

    1998-11-01

    A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range.

  9. Comparison of the NIST and BIPM Standards for Air Kerma in Medium-Energy X-Rays.

    PubMed

    Burns, D T; O'Brien, M

    2006-01-01

    A comparison has been made of the air-kerma standards for medium-energy x-rays of the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and three NIST reference-class transfer ionization chamber standards. Reference beam qualities in the range from 100 kV to 250 kV were used. The results show the standards to be in reasonable agreement within the combined standard uncertainty of the comparison of 0.37 %, although a significant trend with radiation quality is observed and the possible sources discussed.

  10. Determination of the energy dependence of the BC-408 plastic scintillation detector in medium energy x-ray beams

    NASA Astrophysics Data System (ADS)

    Yücel, H.; Çubukçu, Ş.; Uyar, E.; Engin, Y.

    2014-11-01

    The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40-100 kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method. The response of BC-408 PS increased gradually with increasing energy in the energy range of 40-80 kVp and then showed a flat behavior at about 80 to 120 kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology.

  11. Variations in semiconductor device response in a medium-energy x-ray dose-enhancing environment

    SciTech Connect

    Beutler, D.E.; Fleetwood, D.M.; Beezhold, W.; Knott, D.; Lorence, L.J. Jr.; Draper, B.L.

    1987-01-01

    A series of experiments was performed to investigate the response of semiconductor devices to medium-energy x-ray irradiation under conditions in which dose-enhancement effects are very important. The response of MOS capacitors to ''dose-enhanced'' radiation can depend on incident radiation spectra, temperature of the device, and oxide electric field. Indeed, the amount of enhanced response can vary by as much as a factor of 10 as these conditions are changed. In such cases, it appears that changes in electron-hole recombination and hole trapping as a function of radiation energy are very important to the interpretation of the results. Therefore, coupled electron/photon transport codes such as the Monte Carlo integrated TIGER series (ITS), which consider only changes in the dose deposited in the device active region, are inadequate, at least in some cases, for predictions of dose-enhancement effects in semiconductor devices. In addition, the response of semiconductor diodes to dose-enhanced radiation appears to be qualitatively different from that of capacitors, and differs markedly in value from code predictions. Hence, an understanding of the modification of incident radiation by its interactions with dose-enhancing materials alone is insufficient to predict the response of semiconductor devices. The dependence of the device response on radiation spectra, electron-hole recombination, and hole transport and trapping, must also be included to assure good simulation fidelity of tests for devices to be used in dose-enhancing environments.

  12. Variations in semiconductor device response in a medium-energy x-ray dose-enhancing environment

    SciTech Connect

    Beutler, D.E.; Fleetwood, D.M.; Beezhold, W.; Knott, D.; Lorence, L.J. Jr.; Draper, B.L.

    1987-12-01

    The authors performed a series of experiments to investigate the response of semiconductor devices to medium-energy x-ray irradiation under conditions in which dose-enhancement effects are very important. They find that the response of MOS capacitors to the same ''dose-enhanced'' radiation depends not only on the increased dose, but also on the incident radiation spectra, device temperature and processing, and/or oxide thickness and electric field. In many cases, these dependencies cannot be explained simply in terms of existing knowledge of basic mechanisms of radiation effects on MOS devices (for example, electron-hole recombination and hole transport and trapping), or by present Monte Carlo electron/photon transport codes such as the Integrated Tiger Series (ITS). In addition, the response of semiconductor diodes to the ''dose-enhanced'' radiation appears to be qualitatively different from that of MOS capacitors, and differs markedly in value from the ITS code predictions. These results demonstrate that an improved understanding of semiconductor device response to ''enhanced'' radiation is needed to assure simulation fidelity of tests of devices to be used in dose-enhancing environments.

  13. The soft and medium-energy X-ray variability of NGC 5548: a reanalysis of EXOSAT observations.

    NASA Astrophysics Data System (ADS)

    Tagliaferri, G.; Bao, G.; Israel, G. L.; Stella, L.; Treves, A.

    1996-02-01

    The authors carried out cross-correlation function (CCF) and power spectrum re-analysis of the X-ray light curves of the bright Seyfert 1 galaxy NGC 5548 obtained with EXOSAT. The CCF peaks are in all cases consistent with the absence of delays between X-ray variations at different energies. This is unlike the results found by several authors based on the same data. A detailed search for quasi-periodic oscillations (QPOs), using a new technique for the detection of QPOs even in the presence of source noise variability, did not find significant peaks above the 95% confidence detection threshold. The authors discuss and compare their results with those of Papadakis and Lawrence (1993).

  14. ART-XC: A Medium-energy X-ray Telescope System for the Spectrum-R-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Arefiev, V.; Pavlinsky, M.; Lapshov, I.; Thachenko, A.; Sazonov, S.; Revnivtsev, M.; Semena, N.; Buntov,M.; Vikhlinin, A.; Gubarev, M.; hide

    2008-01-01

    The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18 x 18 arcminutes(exp 2) and the sensitivity of the ART-XC system for 4 years of survey will be better than 10(exp -12) erg s(exp -1) cm(exp -2) over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousand new AGNs.

  15. ART-XC: a medium-energy x-ray telescope system for the Spectrum-R-Gamma mission

    NASA Astrophysics Data System (ADS)

    Arefiev, V.; Pavlinsky, M.; Lapshov, I.; Tkachenko, A.; Sazonov, S.; Revnivtsev, M.; Semena, N.; Buntov, M.; Vikhlinin, A.; Gubarev, M.; O'Dell, S.; Ramsey, B.; Romaine, S.; Swartz, D.; Weisskopf, M.; Hasinger, G.; Predehl, P.; Grigorovich, S.; Litvin, D.; Meidinger, N.; Strüder, L. W.

    2008-07-01

    The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow the detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18×18 arcminutes2 and the sensitivity of the ART-XC system for 4 years of survey will be better than 10-12 erg s-1 cm-2 over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousands new AGNs.

  16. First international comparison of primary absorbed dose to water standards in the medium-energy X-ray range

    NASA Astrophysics Data System (ADS)

    Büermann, Ludwig; Guerra, Antonio Stefano; Pimpinella, Maria; Pinto, Massimo; de Pooter, Jacco; de Prez, Leon; Jansen, Bartel; Denoziere, Marc; Rapp, Benjamin

    2016-01-01

    This report presents the results of the first international comparison of primary measurement standards of absorbed dose to water for the medium-energy X-ray range. Three of the participants (VSL, PTB, LNE-LNHB) used their existing water calorimeter based standards and one participant (ENEA) recently developed a new standard based on a water-graphite calorimeter. The participants calibrated three transfer chambers of the same type in terms of absorbed dose to water (NDw) and in addition in terms of air kerma (NK) using the CCRI radiation qualities in the range 100 kV to 250 kV. The additional NK values were intended to be used for a physical analysis of the ratios NDw/NK. All participants had previously participated in the BIPM.RI(I)-K3 key comparison of air kerma standards. Ratios of pairs of NMI's NK results of the current comparison were found to be consistent with the corresponding key comparison results within the expanded uncertainties of 0.6 % - 1 %. The NDw results were analysed in terms of the degrees of equivalence with the comparison reference values which were calculated for each beam quality as the weighted means of all results. The participant's results were consistent with the reference value within the expanded uncertainties. However, these expanded uncertainties varied significantly and ranged between about 1-1.8 % for the water calorimeter based standards and were estimated at 3.7 % for the water-graphite calorimeter. It was shown previously that the ratios NDw/NK for the type of ionization chamber used as transfer chamber in this comparison were very close (within less than 1 %) to the calculated values of (bar muen/ρ)w,ad, the mean values of the water-to-air ratio of the mass-energy-absorption coefficients at the depth d in water. Some of the participant's results deviated significantly from the expected behavior. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of

  17. Observing soft X-ray line emission from the interstellar medium with X-ray calorimeter on a sounding rocket

    NASA Technical Reports Server (NTRS)

    Zhang, J.; Edwards, B.; Juda, M.; Mccammon, D.; Skinner, M.; Kelley, R.; Moseley, H.; Schoelkopf, R.; Szymkowiak, A.

    1990-01-01

    For an X-ray calorimeter working at 0.1 K, the energy resolution ideally can be as good as one eV for a practical detector. A detector with a resolution of 17 eV FWHM at 6 keV has been constructed. It is expected that this can be improved by a factor of two or more. With X-ray calorimeters flown on a sounding rocket, it should be possible to observe soft X-ray line emission from the interstellar medium over the energy range 0.07 to 1 keV. Here, a preliminary design for an X-ray calorimeter rocket experiment and the spectrum which might be observed from an equilibrium plasma are presented. For later X-ray calorimeter sounding rocket experiments, it is planned to add an aluminum foil mirror with collecting area of about 400 sq cm to observe line features from bright supernova remnants.

  18. KEY COMPARISON: APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Hwang, W. S.; Kotler, L. H.; Webb, D. V.; Büermann, L.; Burns, D. T.; Takeyeddin, M.; Shaha, V. V.; Srimanoroth, S.; Meghzifene, A.; Hah, S. H.; Chun, K. J.; Kadni, T. B.; Takata, N.; Msimang, Z.

    2008-01-01

    The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  19. The Soft and Medium-Energy X-Ray Variability of NGC 5548: A Reanalysis of EXOSAT Observations

    NASA Astrophysics Data System (ADS)

    Tagliaferri, G.; Bao, G.; Israel, G. L.; Stella, L.; Treves, A.

    1996-07-01

    We present a detailed cross-correlation (CCF) and power spectrum reanalysis of the X-ray light curves of the bright Seyfert 1 galaxy NGC 5548 obtained with EXOSAT. The 0.05-2 keV and 1-4 keV light curves are cross-correlated with the 1-9 keV and 4-9 keV light curves, respectively. We discuss how spurious time lags can be introduced by systematic effects related to detector swapping as well as the switching on and off of the instruments. We also find strong evidence that one of the ME detectors was not working normally during the second part of the 1986 March observation. When these effects are taken into account, the CCF peaks are in all cases consistent with the absence of delays between X-ray variations at different energies. This is unlike the results found by several authors based on the same data. The power spectra of the 1-9 keV light curves are calculated, and a detailed search for quasi-periodic oscillations (QPOs) is carried out on these spectra by using a new technique for the detection of periodic (or quasi-periodic) signals even in the presence of source noise variability. No significant peaks are found above the 95% confidence detection threshold, except during the second part of the 1986 March observation, most probably as a consequence of the ME detector malfunctioning. We discuss and compare our results with those published by Papadakis & Lawrence in 1993.

  20. SU-F-I-13: Correction Factor Computations for the NIST Ritz Free Air Chamber for Medium-Energy X Rays

    SciTech Connect

    Bergstrom, P

    2016-06-15

    Purpose: The National Institute of Standards and Technology (NIST) uses 3 free-air chambers to establish primary standards for radiation dosimetry at x-ray energies. For medium-energy × rays, the Ritz free-air chamber is the main measurement device. In order to convert the charge or current collected by the chamber to the radiation quantities air kerma or air kerma rate, a number of correction factors specific to the chamber must be applied. Methods: We used the Monte Carlo codes EGSnrc and PENELOPE. Results: Among these correction factors are the diaphragm correction (which accounts for interactions of photons from the x-ray source in the beam-defining diaphragm of the chamber), the scatter correction (which accounts for the effects of photons scattered out of the primary beam), the electron-loss correction (which accounts for electrons that only partially expend their energy in the collection region), the fluorescence correction (which accounts for ionization due to reabsorption ffluorescence photons and the bremsstrahlung correction (which accounts for the reabsorption of bremsstrahlung photons). We have computed monoenergetic corrections for the NIST Ritz chamber for the 1 cm, 3 cm and 7 cm collection plates. Conclusion: We find good agreement with other’s results for the 7 cm plate. The data used to obtain these correction factors will be used to establish air kerma and it’s uncertainty in the standard NIST x-ray beams.

  1. X-ray constraints on the intergalactic medium

    NASA Technical Reports Server (NTRS)

    Aldcroft, Thomas; Elvis, Martin; Mcdowell, Jonathan; Fiore, Fabrizio

    1994-01-01

    We use ROSAT Position Sensitive Proportional Counter (PSPC) spectra of z approximately equal 3 quasars to constrain the density and temperature of the intergalactic medium (IGM). Strong low-energy cutoffs in PSPC spectra of high-redshift quasars are common. However, the absence of absorption toward some high-redshift quasars can be used to put limits on the possible cosmological density, Omega(sub G), of a hot diffuse intergalactic medium (IGM), via an X-ray Gunn-Peterson test using edge and line opacity in the soft X-rays. The K-edges of oxygen, neon, and carbon and the L-edge of iron produce most of the absorption which is spread out by the redshift of the source. We assume an isotropic, isothermal, nonevolving model of the IGM and calculate the optical depth of this absorption. We find that this test can constrain an enriched IGM at temperatures near 10(exp 5) - 10(exp 6) K, intermediate between the hot IGM ruled out by COBE, and the cold IGM ruled out by the traditional Ly alpha Gunn -Peterson test. Photoionization if the IGM by the ultraviolet and X-ray background has a large effect. We give results for three z approximately equal 3 quasars and discuss how the various trade-offs among temperature, abundance, and backgroud radiation strength affect the limits on Omega (sub G). In addition to the high-redshift case, we discuss techniques for constraining the IGM using X-ray spectra of low-redhift quasars (z approximately equal 0.1 - 0.3). Currently available X-ray spectral data have insufficient energy resolution to constrain the IGM umambiguously, and so expected detection limits for future high-resolution spectrometers are presented. We find that with a large effective area (approximately 2000 sq cm), it is possible to substantially constrain or detect the IGM at the densities which are typically predicted.

  2. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays.

    PubMed

    Burns, D T; Kessler, C; O'Brien, M; Minniti, R

    2012-01-01

    A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 10(3), except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

  3. The LNE-LNHB water calorimeter for primary measurement of absorbed dose at low depth in water: application to medium-energy x-rays.

    PubMed

    Rapp, B; Perichon, N; Denoziere, M; Daures, J; Ostrowsky, A; Bordy, J-M

    2013-05-07

    Water calorimeters are used to establish absorbed dose standards in several national metrology laboratories involved in ionizing radiation dosimetry. These calorimeters have been first used in high-energy photons of (60)Co or accelerator beams, where the depth of measurement in water is large (5 or 10 cm). The LNE-LNHB laboratory has developed a specific calorimeter which makes measurements at low depth in water (down to 0.5 cm) easier, in order to fulfil the reference conditions required by the international dosimetry protocols for medium-energy x-rays. This new calorimeter was first used to measure the absorbed dose rate in water at a depth of 2 cm for six medium-energy x-ray reference beams with a tube potential from 80 to 300 kV. The relative combined standard uncertainty obtained on the absorbed dose rate to water is lower than 0.8%. An overview of the design of the calorimeter is given, followed by a detailed description of the calculation of the correction factors and the calorimetric measurements.

  4. A graphite calorimeter for absolute measurements of absorbed dose to water: application in medium-energy x-ray filtered beams.

    PubMed

    Pinto, M; Pimpinella, M; Quini, M; D'Arienzo, M; Astefanoaei, I; Loreti, S; Guerra, A S

    2016-02-21

    The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) has designed and built a graphite calorimeter that, in a water phantom, has allowed the determination of the absorbed dose to water in medium-energy x-rays with generating voltages from 180 to 250 kV. The new standard is a miniaturized three-bodies calorimeter, with a disc-shaped core of 21 mm diameter and 2 mm thickness weighing 1.134 g, sealed in a PMMA waterproof envelope with air-evacuated gaps. The measured absorbed dose to graphite is converted into absorbed dose to water by means of an energy-dependent conversion factor obtained from Monte Carlo simulations. Heat-transfer correction factors were determined by FEM calculations. At a source-to-detector distance of 100 cm, a depth in water of 2 g cm(-2), and at a dose rate of about 0.15 Gy min(-1), results of calorimetric measurements of absorbed dose to water, D(w), were compared to experimental determinations, D wK, obtained via an ionization chamber calibrated in terms of air kerma, according to established dosimetry protocols. The combined standard uncertainty of D(w) and D(wK) were estimated as 1.9% and 1.7%, respectively. The two absorbed dose to water determinations were in agreement within 1%, well below the stated measurement uncertainties. Advancements are in progress to extend the measurement capability of the new in-water-phantom graphite calorimeter to other filtered medium-energy x-ray qualities and to reduce the D(w) uncertainty to around 1%. The new calorimeter represents the first implementation of in-water-phantom graphite calorimetry in the kilovoltage range and, allowing independent determinations of D(w), it will contribute to establish a robust system of absorbed dose to water primary standards for medium-energy x-ray beams.

  5. Low energy x-ray spectrometer

    SciTech Connect

    Woodruff, W.R.

    1981-06-05

    A subkilovolt spectrometer has been produced to permit high-energy-resolution, time-dependent x-ray intensity measurements. The diffracting element is a curved mica (d = 9.95A) crystal. To preclude higher order (n > 1) diffractions, a carbon x-ray mirror that reflects only photons with energies less than approx. 1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold-surface photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminium light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any uv generated on or scattered by the crystal from illuminating the detector. High spectral energy resolution is provided by many photocathodes between 8- and 50-eV wide placed serially along the diffracted x-ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni L..cap alpha../sub 1/ /sub 2/ lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x-ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut-off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x-ray sources. The curved mica crystal diffraction efficiency was measured on our Low-Energy x-ray (LEX) machine. The spectrometer performs well although some changes in the way the x-ray mirror is held are desirable. 16 figures.

  6. Fixed energy X-ray absorption voltammetry.

    PubMed

    Minguzzi, Alessandro; Lugaresi, Ottavio; Locatelli, Cristina; Rondinini, Sandra; D'Acapito, Francesco; Achilli, Elisabetta; Ghigna, Paolo

    2013-08-06

    In this paper, the fixed energy X-ray absorption voltammetry (FEXRAV) is introduced. FEXRAV represents a novel in situ X-ray absorption technique for fast and easy preliminary characterization of electrode materials and consists of recording the absorption coefficient at a fixed energy while varying at will the electrode potential. The energy is chosen close to an X-ray absorption edge, in order to give the maximum contrast between different oxidation states of an element. It follows that any shift from the original oxidation state determines a variation of the absorption coefficient. Although the information given by FEXRAV obviously does not supply the detailed information of X-ray absorption near edge structure (XANES) or extended X-ray absorption fine structure (EXAFS), it allows to quickly map the oxidation states of the element under consideration within the selected potential windows. This leads to the rapid screening of several systems under different experimental conditions (e.g., nature of the electrolyte, potential window) and is preliminary to more deep X-ray absorption spectroscopy (XAS) characterizations, like XANES or EXAFS. In addition, the time-length of the experiment is much shorter than a series of XAS spectra and opens the door to kinetic analysis.

  7. Calorimetric determination of the absorbed dose to water for medium-energy x-rays with generating voltages from 70 to 280 kV.

    PubMed

    Krauss, A; Büermann, L; Kramer, H-M; Selbach, H-J

    2012-10-07

    For medium energy x-rays produced with tube voltages from 70 to 280 kV, the absorbed dose to water, D(w), has been determined by means of water calorimetry with relative standard uncertainties ranging from 0.45% to 0.98% at 280 and 70 kV. The results were confirmed by Monte Carlo calculations, in which the ratios of D(w) at 5 cm depth in a reference water phantom to the air kerma free in air, K(a), at the same point in space were compared to the corresponding ratios determined experimentally. The general agreement between measurement and calculation was better than 1%. These results confirm earlier investigations in which the absorbed dose to graphite was determined by means of a graphite extrapolation chamber. For the Monte Carlo calculations, an attempt was made to present a complete uncertainty budget, taking into account type B contributions also.

  8. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays

    NASA Astrophysics Data System (ADS)

    Burns, D. T.; Kessler, C.; O'Brien, M.; Minniti, R.

    2017-01-01

    A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 103, except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. X-Ray Transition Energies Database

    National Institute of Standards and Technology Data Gateway

    SRD 128 X-Ray Transition Energies Database (Web, free access)   This X-ray transition table provides the energies and wavelengths for the K and L transitions connecting energy levels having principal quantum numbers n = 1, 2, 3, and 4. The elements covered include Z = 10, neon to Z = 100, fermium. There are two unique features of this data base: (1) a serious attempt to have all experimental values on a scale consistent with the International System of measurement (the SI) and (2) inclusion of accurate theoretical estimates for all transitions.

  10. Refractive microlens array for wave-front analysis in the medium to hard x-ray range.

    PubMed

    Mayo, Sheridan C; Sexton, Brett

    2004-04-15

    We report an alternative approach to x-ray wave-front analysis that uses a refractive microlens array as a Shack-Hartmann sensor. The sensor was manufactured by self-assembly and electroplating techniques and is suitable for high-resolution wave-front analysis of medium to hard x rays. We demonstrate its effectiveness at an x-ray energy of 3 keV for analysis of x-ray wave-front perturbations caused by microscopic objects. The sensor has potential advantages over other methods for x-ray phase imaging and will also be useful for the characterization of x-ray beams and optics.

  11. Energy Scales in X-Ray Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Tillotson, W. A.; Boyce, K. R.; Brown, G. V.; Cottam, J.; Figueroa, E.; Kelley, R. L.; Porter, F. S.; Stahle, C. K.

    2003-01-01

    Microcalorimeter pulse shape characteristics, such as pulse height, decay time and rise time, are dependent on the detector temperature and bias as well as the photon energy and flux. We examine the nature of the temperature dependency by illuminating the ASTRO-E2 X-ray Spectrometer (XRS) microcalorimeter array with X-rays generated by electron impact on a range of foil targets. The resulting pulses are collected for a range of detector temperatures. We observe and model the temperature dependence of the pulse shape characteristics by fitting the data with non-linear pulse models. Our aim is to determine a robust method for correcting the energy scale obtained in ground calibration for slight differences in the operating conditions while in orbit.

  12. Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Pinto, C.; Kaastra, J. S.; Costantini, E.; de Vries, C.

    2013-03-01

    Context. The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. Aims: We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). Methods: We used high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measured the column densities of O, Ne, Mg, and Fe with an empirical model and estimated the Galactic abundance gradients. Results: The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25% and 65-90% of the total amount of O i and Fe i is found in dust. The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Conclusions: Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.

  13. The high energy X-ray universe

    PubMed Central

    Giacconi, Riccardo

    2010-01-01

    Since its beginning in the early 1960s, the field of X-ray astronomy has exploded, experiencing a ten-billion-fold increase in sensitivity, which brought it on par with the most advanced facilities at all wavelengths. I will briefly describe the revolutionary first discoveries prior to the launch of the Chandra and XMM-Newton X-ray observatories, present some of the current achievements, and offer some thoughts about the future of this field. PMID:20404148

  14. Simultaneous profile measurements of medium- and high-Z impurity concentrations (nZ/ne) , Te , ΔZeff and n e2Zeff in MCF plasmas from multi-energy x-rays

    NASA Astrophysics Data System (ADS)

    Maddox, Jacob; Delgado-Aparicio, Luis; Pablant, Novimir; Rutman, Max; Hill, Ken; Bitter, Manfred; Reinke, Matthew; Rice, John

    2016-10-01

    Novel energy resolved measurements of x-ray emissions were used to characterize impurity concentrations, electron temperature, and ΔZeff in a variety of Alcator C-Mod plasmas. A PILATUS2 detector programmed in a multi-energy configuration and used in a pinhole camera geometry provides the capability to function similar to a pulse height analyzer (PHA) but with full plasma profile views and sufficient spatial ( 1 cm), energy ( .5 keV), and temporal ( 10 ms) resolution. Each of the PILATUS2's 100k (487x195) pixels can be set to an energy threshold, which sorts x-ray emissions into energy bins by counting only photons with energy above the threshold energy. By setting every 13th pixel row to the same energy bin and the 12 interjacent pixel rows to different energy bins on the PILATUS2 detector gives 38 poloidal sightlines (487 rows/13 energy bins). The number of photons detected in each energy bin depends on (nZ/ne) , Te, and ne2Zeff, so that these plasma parameters can be extracted by fitting the data to an emission model, which includes free-free, free-bound, and bound-bound emissions from a De/H background plasma with perturbing medium and high-Z impurities, like intrinsic Mo, Fe, and Cu or injected W. Also, radial electron temperature profiles were measured during LHRF and ICRF and compared to Thomson scattering and ECE.

  15. Oxygen, Neon, and Iron X-Ray Absorption in the Local Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.; Mendoza, Claudio

    2016-01-01

    We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer. Methods. By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources. Results. We have determined the absorbing material distribution as a function of source distance and galactic latitude longitude. Conclusions. Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.

  16. ISMabs: A COMPREHENSIVE X-RAY ABSORPTION MODEL FOR THE INTERSTELLAR MEDIUM

    SciTech Connect

    Gatuzz, E.; Mendoza, C.; García, J.; Kallman, T. R.; Gorczyca, T. W. E-mail: claudio@ivic.gob.ve E-mail: timothy.r.kallman@nasa.gov

    2015-02-10

    We present an X-ray absorption model for the interstellar medium, to be referred to as ISMabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available. Using high-resolution spectra from eight X-ray binaries obtained with the Chandra High Energy Transmission Grating Spectrometer, we proceed to benchmark the atomic data in the model particularly in the neon K-edge region. Compared with previous photoabsorption models, which solely rely on neutral species, the inclusion of ions leads to improved spectral fits. Fit parameters comprise the column densities of abundant contributors that allow direct estimates of the ionization states. ISMabs is provided in the appropriate format to be implemented in widely used X-ray spectral fitting packages such as XSPEC, ISIS, and SHERPA.

  17. ISMabs: A Comprehensive X-Ray Absorption Model for the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Gatuzz, E.; García, J.; Kallman, T. R.; Mendoza, C.; Gorczyca, T. W.

    2015-02-01

    We present an X-ray absorption model for the interstellar medium, to be referred to as ISMabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available. Using high-resolution spectra from eight X-ray binaries obtained with the Chandra High Energy Transmission Grating Spectrometer, we proceed to benchmark the atomic data in the model particularly in the neon K-edge region. Compared with previous photoabsorption models, which solely rely on neutral species, the inclusion of ions leads to improved spectral fits. Fit parameters comprise the column densities of abundant contributors that allow direct estimates of the ionization states. ISMabs is provided in the appropriate format to be implemented in widely used X-ray spectral fitting packages such as XSPEC, ISIS, and SHERPA.

  18. High energy resolution off-resonant X-ray spectroscopy

    SciTech Connect

    Wojciech, Blachucki

    2015-10-16

    This work treats of the high energy resolution off-resonant X-ray spectroscopy (HEROS) method of determining the density of unoccupied electronic states in the vicinity of the absorption edge. HEROS is an alternative to the existing X-ray absorption spectroscopy (XAS) methods and opens the way for new studies not achievable before.

  19. Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS)

    NASA Technical Reports Server (NTRS)

    Murray, Stephen S.; Pierce, David L. (Technical Monitor)

    2002-01-01

    The Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS) is an astrophysics mission concept for measuring the polarization of X-ray sources at low energies below the C-K band (less than 277 eV). PLEXAS uses the concept of variations in the reflectivity of a multilayered X-ray telescope as a function of the orientation of an X-rays polarization vector with respect to the reflecting surface of the optic. By selecting an appropriate multilayer, and rotating the X-ray telescope while pointing to a source, there will be a modulation in the source intensity, as measured at the focus of the telescope, which is proportional to the degree of polarization in the source.

  20. Low Energy X-Ray and Electron Interactions within Matter.

    DTIC Science & Technology

    1980-03-01

    0-C3962 HAWAII] UNIV HONOLULU DEPT OF PHYSICS AND AST/RONiOMY FmI SelfLOW ENERGY X-RAY AND ELECTRON INTERACTIONS WITHIN MATTER.1U) 14M a L HEM Ai -79...U UNCLASSIFIED AFMWTI olL E iiEEEEEsoE II,,,,hEEIN Eh~hEhh~hhhmmEEmhEEAhE Xbo R-TE. 8oo194 DV , LOW ENERGY X-RAY AND ELECTRON INTERACTIONS WITHIN...ACCESSION NO 3. RECiPIENT’S CATALOG NUMBER TITLE (and SublIII.) 5. TYPE OF REPORT & PERIOD COVERE? LOW ENERGY X-RAY AND ELECTRON INTERACTIONS // Interim A

  1. Dual Energy X-Ray Densitometry Apparatus and Method Using Single X-Ray Pulse

    DTIC Science & Technology

    1999-10-13

    absorptiometry ( DEXA ) projection scanning units have been developed by Hologic Inc. (Waltham, MA) and Lunar Corp. (Madison, Wl). Using dual-energy...of the techniques that have been used, quantitative computed tomography (QCT) x-ray scanning techniques produce three- PATENT NC 79,057...determined by most DEXA instruments, and this quantity is usually referred to as the bone mineral density (BMD). The primary goal for a DEXA instrument

  2. Distinctive features of photoionized plasma from short x-ray-pulse interaction with gaseous medium

    SciTech Connect

    Bychenkov, V.Yu.; Romanov, D.V.; Rozmus, W.; Capjack, C.E.; Fedosejevs, R.

    2006-01-15

    The study of a photoionized plasma created through the interaction of a short linearly polarized x-ray pulse with a gaseous medium is presented in the context of the future design of experiments involving femtosecond free-electron laser pulses. The dispersion properties and instabilities of such x-ray-produced plasma are studied. It is shown that a two-stream type of instability can be obtained with a growth rate comparable to the plasma frequency. This is expected to have a dramatic effect on the evolution of an x-ray laser-produced plasma. A model for describing electromagnetic-field generation and emission resulting from the interaction of a short x-ray laser pulse with a gas jet is proposed. Issues addressed include the effect of the thermal electromotive force at the edge of a plasma driven by the anisotropic electron energy distribution that arises from the photoionization of a gas. Terahertz pulse emission from these photoionized plasma is also predicted.

  3. The High Energy X-ray Probe (HEX-P)

    NASA Astrophysics Data System (ADS)

    Harrison, Fiona; HEX-P Collaboration Collaboration

    2017-01-01

    The High-Energy X-ray Probe (HEX-P) is a probe-class ( 500M) next-generation high-energy X-ray observatory with broadband (2-200 keV) response and 40 times the sensitivity of any previous mis-sion in the 10-80 keV band, and >500 times the sensitivity of any previous mission in the 80-200 keV band. Intended to launch contemporaneously with Athena, HEX-P will provide fundamental new discoveries that range from resolving 90% of the X-ray background at its peak, to measuring the cosmic evolution of black hole spin, to studying faint X-ray populations in nearby galaxies. Based on NuSTAR heritage, HEX-P requires only modest technology development, and could easily be executed within the next decade.

  4. Treatment of foods with high-energy X rays

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Meissner, J.; Herer, A. S.; Beers, E. W.

    2001-07-01

    The treatment of foods with ionizing energy in the form of gamma rays, accelerated electrons, and X rays can produce beneficial effects, such as inhibiting the sprouting in potatoes, onions, and garlic, controlling insects in fruits, vegetables, and grains, inhibiting the growth of fungi, pasteurizing fresh meat, poultry, and seafood, and sterilizing spices and food additives. After many years of research, these processes have been approved by regulatory authorities in many countries and commercial applications have been increasing. High-energy X rays are especially useful for treating large packages of food. The most attractive features are product penetration, absorbed dose uniformity, high utilization efficiency and short processing time. The ability to energize the X-ray source only when needed enhances the safety and convenience of this technique. The availability of high-energy, high-power electron accelerators, which can be used as X-ray generators, makes it feasible to process large quantities of food economically. Several industrial accelerator facilities already have X-ray conversion equipment and several more will soon be built with product conveying systems designed to take advantage of the unique characteristics of high-energy X rays. These concepts will be reviewed briefly in this paper.

  5. High resolution, large area, high energy x-ray tomography

    SciTech Connect

    Trebes, J.E.; Dolan, K.W.; Haddad, W.S.; Haskins, J.J.; Lerche, R.A.; Logan, C.M.; Perkins, D.E.; Schneberk, D.J.; Rikard, R.D.

    1997-08-01

    An x-ray tomography system is being developed for high resolution inspection of large objects. The goal is to achieve 25 micron resolution over object sizes that are tens of centimeters in extent. Typical objects will be metal in composition and therefore high energy, few MeV x-rays will be required. A proof-of-principle system with a limited field of view has been developed. Preliminary results are presented.

  6. Diagnostic Spectrometers for High Energy Density X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Hudson, L. T.; Henins, A.; Seely, J. F.; Holland, G. E.

    2007-08-01

    A new generation of advanced laser, accelerator, and plasma confinement devices are emerging that are producing extreme states of light and matter that are unprecedented for laboratory study. Examples of such sources that will produce laboratory x-ray emissions with unprecedented characteristics include megajoule-class and ultrafast, ultraintense petawatt laser-produced plasmas; tabletop high-harmonic-generation x-ray sources; high-brightness zeta-pinch and magnetically confined plasma sources; and coherent x-ray free electron lasers and compact inverse-Compton x-ray sources. Characterizing the spectra, time structure, and intensity of x rays emitted by these and other novel sources is critical to assessing system performance and progress as well as pursuing the new and unpredictable physical interactions of interest to basic and applied high-energy-density (HED) science. As these technologies mature, increased emphasis will need to be placed on advanced diagnostic instrumentation and metrology, standard reference data, absolute calibrations and traceability of results. We are actively designing, fabricating, and fielding wavelength-calibrated x-ray spectrometers that have been employed to register spectra from a variety of exotic x-ray sources (electron beam ion trap, electron cyclotron resonance ion source, terawatt pulsed-power-driven accelerator, laser-produced plasmas). These instruments employ a variety of curved-crystal optics, detector technologies, and data acquisition strategies. In anticipation of the trends mentioned above, this paper will focus primarily on optical designs that can accommodate the high background signals produced in HED experiments while also registering their high-energy spectral emissions. In particular, we review the results of recent laboratory testing that explores off-Rowland circle imaging in an effort to reclaim the instrumental resolving power that is increasingly elusive at higher energies when using wavelength

  7. Comprehensive x-ray spectral code for high energy astrophysics

    SciTech Connect

    Liedahl, D A; Fournier, K B; Mauche, C W

    2000-08-18

    The aim of this project has been to develop a spectral analysis tool with a level of quality and completeness commensurate to that expected in data from the current generation of X-ray observatories. The code is called LXSS (Livermore X-Ray Spectral Synthesizer). X-ray-emitting astrophysical plasmas are rarely, if ever, in LTE, so they have adopted the detailed level accounting approach, in which rates for processes that populate or depopulate atomic energy levels are treated explicitly. This entails the generation of a large quantity of atomic data, most of which is calculated using ''in-house'' computer codes. Calculations are benchmarked against laboratory data, and spectral models have been used to provide first-time interpretations of astrophysical X-ray spectra. The design of a versatile graphical user interface that allows access to and manipulation of the atomic database comprises the second major part of the project.

  8. Dosimetric properties of high energy current (HEC) detector in keV x-ray beams

    NASA Astrophysics Data System (ADS)

    Zygmanski, Piotr; Shrestha, Suman; Elshahat, Bassem; Karellas, Andrew; Sajo, Erno

    2015-04-01

    We introduce a new x-ray radiation detector. The detector employs high-energy current (HEC) formed by secondary electrons consisting predominantly of photoelectrons and Auger electrons, to directly convert x-ray energy to detector signal without externally applied power and without amplification. The HEC detector is a multilayer structure composed of thin conducting layers separated by dielectric layers with an overall thickness of less than a millimeter. It can be cut to any size and shape, formed into curvilinear surfaces, and thus can be designed for a variety of QA applications. We present basic dosimetric properties of the detector as function of x-ray energy, depth in the medium, area and aspect ratio of the detector, as well as other parameters. The prototype detectors show similar dosimetric properties to those of a thimble ionization chamber, which operates at high voltage. The initial results obtained for kilovoltage x-rays merit further research and development towards specific medical applications.

  9. The Einstein Observatory Extended Medium-Sensitivity Survey. I - X-ray data and analysis

    NASA Technical Reports Server (NTRS)

    Gioia, I. M.; Maccacaro, T.; Schild, R. E.; Wolter, A.; Stocke, J. T.

    1990-01-01

    This paper presents the results of the analysis of the X-ray data and the optical identification for the Einstein Observatory Extended Medium-Sensitivity Survey (EMSS). The survey consists of 835 serendipitous sources detected at or above 4 times the rms level in 1435 imaging proportional counter fields with centers located away from the Galactic plane. Their limiting sensitivities are about (5-300) x 10 to the -14th ergs/sq cm sec in the 0.3-3.5-keV energy band. A total area of 778 square deg of the high-Galactic-latitude sky has been covered. The data have been analyzed using the REV1 processing system, which takes into account the nonuniformities of the detector. The resulting EMSS catalog of X-ray sources is a flux-limited and homogeneous sample of astronomical objects that can be used for statistical studies.

  10. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the VSL, The Netherlands and the BIPM in medium-energy x-rays

    NASA Astrophysics Data System (ADS)

    Burns, D. T.; Kessler, C.; de Pooter, J. A.; Jansen, B. J.

    2016-01-01

    A key comparison has been made between the air-kerma standards of the VSL, The Netherlands and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Correlation Between X-ray And Microwave (sz) Signals From The Warm-hot Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Galeazzi, Massimiliano; Gupta, A.; Huffenberger, K.; Ursino, E.

    2010-05-01

    A large fraction of the low redshift baryons is believed to reside in a warm-hot filamentary gas in the intergalactic medium (WHIM). In the past we have successfully used XMM-Newton data to identify and characterize the WHIM angular signature using the autocorrelation function [Galeazzi 2009, 695, 1127]. Using the output of large scale hydrodynamic simulations we have also investigated the correlation between low energy X-ray emission and SZ effect from WHIM filaments. The largest of the current SZ surveys (with the South Pole Telescope [Ruhl 2004, Proc. SPIE, 5498, 11] and the Atacama Cosmology Telescope [Kosowsky 2004, NAR 47, 939; 2006, NAR 50, 969]) are mapping hundreds of square degrees at arcminute resolution at bands in 100-300 GHz, and have started identifying clusters detected by their SZ signature alone [e.g. Staniszewski 2009, ApJ, 701,32; Hincks 2009, arXiv:0907.0461]. Although the bulk of the total luminosity in the SZ effect is associated with collapsed structures like clusters, our work indicates that a significant fraction comes from unbound objects, mostly from overdense regions, like the WHIM. Due to the unique emission mechanism, the X-ray and SZ correlation provides additional constraints on the structure of the intergalactic gas. Adopting an adiabatic, polytropic model the SZ signal goes as ne1.2, compared with the x-ray emission that goes roughly as ne2 (slightly modified by the cooling function). In this paper we will discuss the result of our investigation on the correlation between X-ray emission and SZ signals and the implications for current X-ray and SZ observatories. We will also present our preliminary applications using actual data.

  12. Exotic X-ray Sources from Intermediate Energy Electron Beams

    SciTech Connect

    Chouffani, K.; Wells, D.; Harmon, F.; Jones, J.L.; Lancaster, G.

    2003-08-26

    High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, 'novel' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic 'structure' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR)

  13. Radiation processing with high-energy X-rays

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.; Stichelbaut, Frédéric

    2013-03-01

    The radiation processing of materials and commercial products with high-energy X-rays, which are also identified by the German term bremsstrahlung, can produce beneficial changes that are similar to those obtained by irradiation with nuclear gamma rays emitted by cobalt-60 sources. Both X-rays and gamma rays are electromagnetic radiations with short wavelengths and high photon energies that can stimulate chemical reactions by creating ions and free radicals in irradiated materials. Nevertheless, there are some physical differences in these energy sources that can influence the choice for practical applications. The English translation of bremsstrahlung is braking radiatiorn or deceleration radiation. It is produced when energetic electrons are deflected by the strong electric field near an atomic nucleus. The efficiency for producing this kind of electromagnetic energy increases with the kinetic energy of the electrons and the atomic number of the target material. The energy spectrum of the emitted X-ray photons is very broad and extends up to the maximum energy of the incident electrons. In contrast, a cobalt-60 nucleus emits two gamma rays simultaneously, which have well-defined energies. Another significant difference is the angular distribution of the radiation. Nuclear gamma rays are emitted in all directions, but high-energy bremsstrahlung photons are concentrated in the direction of the incident electrons when they strike the target material. This property enables an X-ray processing facility to be more compact than a gamma-ray processing facility with similar throughput capacity, and it increases the penetration and the efficiency for absorbing the emitted X-ray energy in the irradiated material. Recent increases in the electron energy and the electron beam power from modern industrial accelerators have increased the throughput rates in X-ray processing facilities, so that this irradiation method is now economically competitive with large cobalt-60

  14. Energy weighted x-ray dark-field imaging.

    PubMed

    Pelzer, Georg; Zang, Andrea; Anton, Gisela; Bayer, Florian; Horn, Florian; Kraus, Manuel; Rieger, Jens; Ritter, Andre; Wandner, Johannes; Weber, Thomas; Fauler, Alex; Fiederle, Michael; Wong, Winnie S; Campbell, Michael; Meiser, Jan; Meyer, Pascal; Mohr, Jürgen; Michel, Thilo

    2014-10-06

    The dark-field image obtained in grating-based x-ray phase-contrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification. In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%.

  15. The High Energy X-ray Imager Technology (HEXITEC) for Solar Hard X-ray Observations

    NASA Astrophysics Data System (ADS)

    Christe, Steven; Shih, Albert Y.; Gaskin, Jessica; Wilson-Hodge, Colleen; Seller, Paul; Wilson, Matthew

    2015-04-01

    High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For current high resolution X-ray mirrors, the HPD is about 25 arcsec. Over a 6-m focal length this converts to 750 µm, the optimum pixel size is around 250 µm. Annother requirement are that the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage. For solar observations, the ability to handle high counting rates is also extremely desirable. The Rutherford Appleton Laboratory (RAL) in the UK has been developing the electronics for such a detector. Dubbed HEXITEC, for High Energy X-Ray Imaging Technology, this Application Specific Integrated Circuit (ASIC), can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT), to create a fine (250 µm pitch) HXR detector. The NASA Marshall Space Flight CenterMSFC and the Goddard Space Flight Center (GSFC) has been working with RAL over the past few years to develop these detectors to be used with HXR focusing telescopes. We present on recent results and capabilities as applied to solar observations.

  16. High-Energy Diffraction-Enhanced X-ray Imaging

    SciTech Connect

    Yoneyama, Akio; Ueda, Kazuhiro; Takeda, Tohoru; Yamazaki, Takanori; Hyodo, Kazuyuki

    2010-06-23

    In order to apply the diffraction-enhanced X-ray imaging (DEI) method for much wider variety of samples, we have developed the high-energy DEI system. The energy of X-ray was increased up to 70 keV to achieve high permeability for heavy elements. The diffraction of Si(440) was used to keep large field of view. Demonstrative observation of an electrical cable was performed using the X-ray emitted from the vertical wiggler. The obtained images visualized not only the core and ground wire made of copper but also the isolator and outer jacket made of polymer clearly. The comparison of images obtained by the DEI and the absorption-contrast imaging showed that the sensitivity of DEI is about 10 times higher than that of the absorption method for light elements, and 3 times for heavy elements.

  17. Focal construct geometry for high intensity energy dispersive x-ray diffraction based on x-ray capillary optics

    NASA Astrophysics Data System (ADS)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Jiang, Bowen; Zhu, Yu

    2016-03-01

    We presented a focal construct geometry (FCG) method for high intensity energy dispersive X-ray diffraction by utilizing a home-made ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL). The ESBC was employed to focus the X-rays from a conventional laboratory source into a small focal spot and to produce an annular X-ray beam in the far-field. Additionally, diffracted polychromatic X-rays were confocally collected by the PPXRL attached to a stationary energy-resolved detector. Our FCG method based on ESBC and PPXRL had achieved relatively high intensity diffraction peaks and effectively narrowed the diffraction peak width which was helpful in improving the potential d-spacing resolution for material phase analysis.

  18. Focal construct geometry for high intensity energy dispersive x-ray diffraction based on x-ray capillary optics.

    PubMed

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Jiang, Bowen; Zhu, Yu

    2016-03-14

    We presented a focal construct geometry (FCG) method for high intensity energy dispersive X-ray diffraction by utilizing a home-made ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL). The ESBC was employed to focus the X-rays from a conventional laboratory source into a small focal spot and to produce an annular X-ray beam in the far-field. Additionally, diffracted polychromatic X-rays were confocally collected by the PPXRL attached to a stationary energy-resolved detector. Our FCG method based on ESBC and PPXRL had achieved relatively high intensity diffraction peaks and effectively narrowed the diffraction peak width which was helpful in improving the potential d-spacing resolution for material phase analysis.

  19. EFFECT OF METALLICITY ON X-RAY EMISSION FROM THE WARM-HOT INTERGALACTIC MEDIUM

    SciTech Connect

    Ursino, E.; Galeazzi, M.; Roncarelli, M.

    2010-09-20

    Hydrodynamic simulations predict that a significant fraction of the gas in the current universe is in the form of high temperature, highly ionized plasma emitting and absorbing primarily in the soft X-ray and UV bands, dubbed the warm-hot intergalactic medium (WHIM). Its signature should be observable in redshifted emission and absorption lines from highly ionized elements. To determine the expected WHIM emission in the soft X-ray band we used the output of a large scale smoothed particle hydrodynamic simulation to generate images and spectra with angular resolution of 14'' and energy resolution of 1 eV. The current biggest limit of any hydrodynamic simulation in predicting the X-ray emission comes from metal diffusion. In our investigation, by using four different models for the WHIM metallicity we have found a strong dependence of the emission on the model used, with differences up to almost an order of magnitude. For each model, we have investigated the redshift distribution and angular scale of the emission, confirming that most photons come from redshift z < 1.2 and that the emission has a typical angular scale of less than a few arcminutes. We also compared our simulations with the few currently available observations and found that, within the variation of the metallicity models, our predictions are in good agreement with current constraints on the WHIM emission, and at this time the weak experimental constraints on the WHIM emission are not sufficient to exclude any of the models used.

  20. Bone age assessment by dual-energy X-ray absorptiometry in children: an alternative for X-ray?

    PubMed

    Heppe, D H M; Taal, H R; Ernst, G D S; Van Den Akker, E L T; Lequin, M M H; Hokken-Koelega, A C S; Geelhoed, J J M; Jaddoe, V W V

    2012-02-01

    The aim of the study was to validate dual-energy X-ray absorptiometry (DXA) as a method to assess bone age in children. Paired dual-energy X-ray absorptiometry (DXA) scans and X-rays of the left hand were performed in 95 children who attended the paediatric endocrinology outpatient clinic of University Hospital Rotterdam, the Netherlands. We compared bone age assessments by DXA scan with those performed by X-ray. Bone age assessment was performed by two blinded observers according to the reference method of Greulich and Pyle. Intra-observer and interobserver reproducibility were investigated using the intraclass correlation coefficient (ICC), and agreement was tested using Bland and Altman plots. The intra-observer ICCs for both observers were 0.997 and 0.991 for X-ray and 0.993 and 0.987 for DXA assessments. The interobserver ICC was 0.993 and 0.991 for X-ray and DXA assessments, respectively. The mean difference between bone age assessed by X-ray and DXA was 0.11 years. The limits of agreement ranged from -0.82 to 1.05 years, which means that 95% of all differences between the methods were covered by this range. Results of bone age assessment by DXA scan are similar to those obtained by X-ray. The DXA method seems to be an alternative for assessing bone age in a paediatric hospital-based population.

  1. X-ray Thomson scattering in high energy density plasmas

    SciTech Connect

    Glenzer, Siegfried H.; Redmer, Ronald

    2009-10-15

    Accurate x-ray scattering techniques to measure the physical properties of dense plasmas have been developed for applications in high energy density physics. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines, allowing spectrally resolved x-ray scattering measurements from these plasmas. The backscattering spectrum accesses the noncollective Compton scattering regime which provides accurate diagnostic information on the temperature, density, and ionization state. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions and quantum effects. Dense matter theory relates scattering spectra with the dielectric function and structure factors that determine the physical properties of matter. Applications to radiation-heated and shock-compressed matter have demonstrated accurate measurements of compression and heating with up to picosecond temporal resolution. The ongoing development of suitable x-ray sources and facilities will enable experiments in a wide range of research areas including inertial confinement fusion, radiation hydrodynamics, material science, or laboratory astrophysics.

  2. Energy-selective filtration of dental x-ray beams

    SciTech Connect

    Gelskey, D.E.; Baker, C.G.

    1981-11-01

    Samarium is known for its ability to filter simultaneously low- and high-energy x-ray photons from an x-ray beam that are not useful in producing a diagnostic radiograph. This study was undertaken to determine the optimum thickness of samarium required to minimize patient exposure and exposure time. The results indicate that use of a filter thickness of 0.16 mm. minimized patient radiation exposure and permitted the use of an exposure time sufficiently short to minimize motion unsharpness. The incorporation of a 0.16 mm. samarium filter in the x-ray beam reduced exposure by about 40 percent as compared to a 2.5 mm. aluminum filter; the exposure time must be increased approximately twice to obtain optical densities equivalent to those produced with aluminum filtration.

  3. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  4. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  5. Energy determination in industrial X-ray processing facilities

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Gregoire, O.; Stichelbaut, F.; Gomola, I.; Galloway, R. A.; Schlecht, J.

    2005-12-01

    In industrial irradiation facilities, the determination of maximum photon or electron energy is important for regulated processes, such as food irradiation, and for assurance of treatment reproducibility. With electron beam irradiators, this has been done by measuring the depth-dose distribution in a homogeneous material. For X-ray irradiators, an analogous method has not yet been recommended. This paper describes a procedure suitable for typical industrial irradiation processes, which is based on common practice in the field of therapeutic X-ray treatment. It utilizes a measurement of the slope of the exponential attenuation curve of X-rays in a thick stack of polyethylene plates. Monte Carlo simulations and experimental tests have been performed to verify the suitability and accuracy of the method between 3 MeV and 8 MeV.

  6. Heating the Intergalactic Medium by X-Rays from Population III Binaries in High-redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Xu, Hao; Ahn, Kyungjin; Wise, John H.; Norman, Michael L.; O'Shea, Brian W.

    2014-08-01

    Due to their long mean free path, X-rays are expected to have an important impact on cosmic reionization by heating and ionizing the intergalactic medium (IGM) on large scales, especially after simulations have suggested that Population III (Pop III) stars may form in pairs at redshifts as high as 20-30. We use the Pop III distribution and evolution from a self-consistent cosmological radiation hydrodynamic simulation of the formation of the first galaxies and a simple Pop III X-ray binary model to estimate their X-ray output in a high-density region larger than 100 comoving (Mpc)3. We then combine three different methods—ray tracing, a one-zone model, and X-ray background modeling—to investigate the X-ray propagation, intensity distribution, and long-term effects on the IGM thermal and ionization state. The efficiency and morphology of photoheating and photoionization are dependent on the photon energies. The sub-kiloelectronvolt X-rays only impact the IGM near the sources, while the kiloelectronvolt photons contribute significantly to the X-ray background and heat and ionize the IGM smoothly. The X-rays just below 1 keV are most efficient in heating and ionizing the IGM. We find that the IGM might be heated to over 100 K by z = 10 and the high-density source region might reach 104 K, limited by atomic hydrogen cooling. This may be important for predicting the 21 cm neutral hydrogen signals. On the other hand, the free electrons from X-ray ionizations are not enough to contribute significantly to the optical depth of the cosmic microwave background to the Thomson scattering.

  7. Heating the intergalactic medium by X-rays from population III binaries in high-redshift galaxies

    SciTech Connect

    Xu, Hao; Norman, Michael L.; Ahn, Kyungjin; Wise, John H.; O'Shea, Brian W. E-mail: mlnorman@ucsd.edu E-mail: jwise@gatech.edu

    2014-08-20

    Due to their long mean free path, X-rays are expected to have an important impact on cosmic reionization by heating and ionizing the intergalactic medium (IGM) on large scales, especially after simulations have suggested that Population III (Pop III) stars may form in pairs at redshifts as high as 20-30. We use the Pop III distribution and evolution from a self-consistent cosmological radiation hydrodynamic simulation of the formation of the first galaxies and a simple Pop III X-ray binary model to estimate their X-ray output in a high-density region larger than 100 comoving (Mpc){sup 3}. We then combine three different methods—ray tracing, a one-zone model, and X-ray background modeling—to investigate the X-ray propagation, intensity distribution, and long-term effects on the IGM thermal and ionization state. The efficiency and morphology of photoheating and photoionization are dependent on the photon energies. The sub-kiloelectronvolt X-rays only impact the IGM near the sources, while the kiloelectronvolt photons contribute significantly to the X-ray background and heat and ionize the IGM smoothly. The X-rays just below 1 keV are most efficient in heating and ionizing the IGM. We find that the IGM might be heated to over 100 K by z = 10 and the high-density source region might reach 10{sup 4} K, limited by atomic hydrogen cooling. This may be important for predicting the 21 cm neutral hydrogen signals. On the other hand, the free electrons from X-ray ionizations are not enough to contribute significantly to the optical depth of the cosmic microwave background to the Thomson scattering.

  8. High-energy X-ray spectra of five sources.

    NASA Technical Reports Server (NTRS)

    Ricker, G. R.; Mcclintock, J. E.; Gerassimenko, M.; Lewin , W. H. G.

    1973-01-01

    On October 15-16, 1970, we carried out balloon X-ray observations from Australia at energies above 15 keV. We present the high-energy X-ray spectra of three sources discovered by us, GX 301-2, GX 304-1, and GX 1 + 4. The data suggest that these high-energy sources correspond to the sources 2U 1223-62, 2U 1258-61, and 2U 1728-24 respectively. We also present the spectra for two additional sources, GX 5-1 (2U 1757-25) and GX 3 + 1 (2U 1744-26). The average intensity of the highly variable source GX 301-2 was observed to be as great as Tau X-1 in the energy range 15-50 keV.

  9. X-ray emission of SNRs in nonuniform medium: properties of thermal and nonthermal spectra

    NASA Astrophysics Data System (ADS)

    Petruk, O.

    2006-05-01

    In this report we consider two effects in the thermal and nonthermal spectra of supernova remnants (SNRs) which could be caused by the nonuniform ISM: i) the mimicry of the thermal X-ray spectrum of SNRs under the nonthermal one and ii) artificial broadening of the high-energy end of the nonthermal X-ray spectrum of SNRs. 1.There is possibility that the nonthermal features in the X-ray spectrum of some supernova remnants may be in fact of the thermal origin. Observed spectrum from SNRs is a superposition of ``individual'' spectra from different small volumes along the line of sight. The plasma is under different conditions in different places in SNR. The thermal X-ray spectrum of emission from a volume with high enough gradients of density and temperature may mimic under nonthermal one. This effect is studied with special attention to the case of supernova remnant evolution in the nonuniform interstellar medium like near molecular cloud. The mimicry-effect may be responsible for the nonthermal properties of X-ray spectra in those SNRs where nonthermal flux in photons with energy < 2 keV is expected to be less than thermal one in et least 2 orders of magnitude. Therefore, the effect cannot be a reason of the nonthermal features in X-ray spectra of SN 1006 and other SNRs where nonthermal flux is estimated to be of order or higher than the thermal one. 2.The observed spectrum of SNR is a superposition of many ``local'' spectra emitted by regions of SNR which are under different physical conditions. Does broadening of the high-energy end of the observed nonthermal spectrum of SNRs, like in G347.3-0.5 and SN 1006, may be an artifact of observations or is it a consequence of the microphysics involved in the acceleration process? In this note we study the influence of parameter variations in the volume and over the surface of SNR on the shape of the high-energy end of the synchrotron spectrum. It is shown that gradients of density and magnetic field strength downstream of

  10. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV.

    PubMed

    Seidenbusch, M; Harder, D; Regulla, D

    2014-05-01

    The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual

  11. An analytical approach to estimating the first order x-ray scatter in heterogeneous medium.

    PubMed

    Yao, Weiguang; Leszczynski, Konrad W

    2009-07-01

    X-ray scatter estimation in heterogeneous medium is a challenge in improving the quality of diagnostic projection images and volumetric image reconstruction. For Compton scatter, the statistical behavior of the first order scatter can be accurately described by using the Klein-Nishina expression for Compton scattering cross section provided that the exact information of the medium including the geometry and the attenuation, which in fact is unknown, is known. The authors present an approach to approximately separate the unknowns from the Klein-Nishina formula and express the unknown part by the primary x-ray intensity at the detector. The approximation is fitted to the exact solution of the Klein-Nishina formulas by introducing one parameter, whose value is shown to be not sensitive to the linear attenuation coefficient and thickness of the scatterer. The performance of the approach is evaluated by comparing the result with those from the Klein-Nishina formula and Monte Carlo simulations. The approximation is close to the exact solution and the Monte Carlo simulation result for parallel and cone beam imaging systems with various field sizes, air gaps, and mono- and polyenergy of primary photons and for nonhomogeneous scatterer with various geometries of slabs and cylinders. For a wide range of x-ray energy including those often used in kilo- and megavoltage cone beam computed tomographies, the first order scatter fluence at the detector is mainly from Compton scatter. Thus, the approximate relation between the first order scatter and primary fluences at the detector is useful for scatter estimation in physical phantom projections.

  12. Phase contrast imaging with coherent high energy X-rays

    SciTech Connect

    Snigireva, I.

    1997-02-01

    X-ray imaging concern high energy domain (>6 keV) like a contact radiography, projection microscopy and tomography is used for many years to discern the features of the internal structure non destructively in material science, medicine and biology. In so doing the main contrast formation is absorption that makes some limitations for imaging of the light density materials and what is more the resolution of these techniques is not better than 10-100 {mu}m. It was turned out that there is now way in which to overcome 1{mu}m or even sub-{mu}m resolution limit except phase contrast imaging. It is well known in optics that the phase contrast is realised when interference between reference wave front and transmitted through the sample take place. Examples of this imaging are: phase contrast microscopy suggested by Zernike and Gabor (in-line) holography. Both of this techniques: phase contrast x-ray microscopy and holography are successfully progressing now in soft x-ray region. For imaging in the hard X-rays to enhance the contrast and to be able to resolve phase variations across the beam the high degree of the time and more importantly spatial coherence is needed. Because of this it was reasonable that the perfect crystal optics was involved like Bonse-Hart interferometry, double-crystal and even triple-crystal set-up using Laue and Bragg geometry with asymmetrically cut crystals.

  13. Flywheel energy storage for x-ray machines.

    PubMed

    Siedband, M P; Showers, D K

    1984-01-01

    X-ray image quality for stop-motion exposures is greatly affected by the system power capability. High power levels are required for adequate resolution, which often precludes the use of mobile x-ray systems for stop-motion exposures. Currently available mobile systems use (1) 90-V nickel-cadmium batteries capable of 120 A, (2) a power line of 220 V ac, 60 Hz capable of about 100 A, or (3) a capacitor discharge unit using 1.0-microF capacitors and limited to 17-mAs equivalent output (compared to three-phase systems at 100 kVp). In each case, instantaneous power is usually limited to 10 kW. An alternative means which now appears to be a practical power source for mobile x-ray systems is the flywheel energy storage system. A 5-kg flywheel has been constructed which runs at 10 000 rpm and stores 25 000 J while drawing only a few hundred watts to bring the system up to speed. When coupled to an aircraft alternator, pulsed power levels of 25 kW have been achieved. The aircraft alternator also has the advantage of high-frequency output which has permitted the use of smaller high-voltage transformers. This system permits the generation of powerful x rays using low-power sources, such as single automobile batteries, common 115-V outlets, or electrical sources of poor regulation such as found in Third World countries.

  14. The Extended Medium Sensitivity Survey distant cluster sample - X-ray cosmological evolution

    SciTech Connect

    Gioia, I.M.; Henry, J.P.; Maccacaro, T.; Morris, S.L.; Stocke, J.T. CNR, Istituto di Radioastronomia, Bologna Hawaii Univ., Honolulu Osservatorio Astronomico, Bologna Mount Wilson and Las Campanas Observatories, Pasadena, CA Colorado Univ., Boulder )

    1990-06-01

    The X-ray luminosity function of clusters of galaxies is determined at different cosmic epochs using data from the Einstein Observatory Extended Medium Sensitivity Survey. The sample consists of 67 X-ray-selected clusters that have been grouped in three redshift shells. Evolution is detected in the X-ray properties of clusters. The present volume density of high-luminosity clusters is found to be greater than it was in the past. Given the still limited data set, this result should be regarded as preliminary. It can be interpreted as the consequence of either luminosity evolution or modest density evolution. 22 refs.

  15. The Extended Medium Sensitivity Survey distant cluster sample - X-ray cosmological evolution

    NASA Technical Reports Server (NTRS)

    Gioia, I. M.; Henry, J. P.; Maccacaro, T.; Morris, S. L.; Stocke, J. T.

    1990-01-01

    The X-ray luminosity function of clusters of galaxies is determined at different cosmic epochs using data from the Einstein Observatory Extended Medium Sensitivity Survey. The sample consists of 67 X-ray-selected clusters that have been grouped in three redshift shells. Evolution is detected in the X-ray properties of clusters. The present volume density of high-luminosity clusters is found to be greater than it was in the past. Given the still limited data set, this result should be regarded as preliminary. It can be interpreted as the consequence of either luminosity evolution or modest density evolution.

  16. Spectacular X-ray Jet Points Toward Cosmic Energy Booster

    NASA Astrophysics Data System (ADS)

    2000-06-01

    NASA's Chandra X-ray Observatory has revealed a spectacular luminous spike of X rays that emanates from the vicinity of a giant black hole in the center of the radio galaxy Pictor A. The spike, or jet, is due to a beam of particles that streaks across hundreds of thousands of light years of intergalactic space toward a brilliant X-ray hot spot that marks its end point. Pictor A Image Press Image and Caption The hot spot is at least 800 thousand light years (8 times the diameter of our Milky Way galaxy) away from where the jet originates. It is thought to represent the advancing head of the jet, which brightens conspicuously where it plows into the tenuous gas of intergalactic space. The jet, powered by the giant black hole, originates from a region of space no bigger than the solar system. "Both the brightness and the spectrum of the X rays are very different from what theory predicts," Professor Andrew Wilson reported today at the 196th national meeting of the American Astronomical Society in Rochester, New York. Wilson, of the University of Maryland, College Park, along with Dr. Patrick Shopbell and Dr. Andrew Young, also of the University of Maryland, are submitting an article on this research to the Astrophysical Journal. "The Chandra observations are telling us that something out there is producing many more high-energy particles than we expected," said Wilson. One possible explanation for the X rays is that shock waves along the side and head of the X-ray jet are accelerating electrons and possibly protons to speeds close to that of light. In the process the electrons are boosted to energies as high as 100 million times their own rest mass energy. These electrons lose their energy rapidly as they produce X rays, so this could be the first direct evidence of this process so far outside a galaxy. The hot spot has been seen with optical and radio telescopes. Radio telescopes have also observed a faint jet. Jets are thought to be produced by the extreme

  17. Elemental quantification using multiple-energy x-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Kozul, N.; Davis, G. R.; Anderson, P.; Elliott, J. C.

    1999-03-01

    A novel implementation of multiple-energy x-ray absorptiometry (MEXA) for elemental quantification has been developed. Species are resolved on the basis of their differential attenuation spectra across a wide energy range, ideally including absorption edges. By measuring the incident and exiting x-ray spectra and using known values of mass attenuation coefficients over selected energy bands, the density line integral of the species along the x-ray path can be calculated from all the selected energy channels simultaneously by non-linear least squares methods. Effects of `escape' peak phenomena are modelled and corrections for them are included in the MEXA software. The applications of MEXA are illustrated by single measurements on aluminium and zirconium foils, quantitation of aqueous KI diffusing into a porous solid, simultaneous measurement of acidic diffusant 0957-0233/10/3/023/img1 and porous solid with which it reacts and which it dissolves and microtomographic reconstructions of liquid and solid specimens containing caesium and/or iodine.

  18. High energy X-ray observations of extragalactic objects

    NASA Technical Reports Server (NTRS)

    Baity, W. A.; Gruber, D. E.; Matteson, J. L.; Knight, F. K.; Nolan, P. L.; Scheepmaker, A.; Wheaton, W. A.; Hofman, J. A.; Primini, F. A.; Lewin, W. H. G.

    1979-01-01

    Preliminary results are reported for scanning observations of the active galaxy NGC 5128 (Cen A) and the Type 1 Seyfert galaxy NGC 4151 with the low-energy detectors of the HEAO-1 A-4 hard X-ray instrument. The X-ray spectra in the energy range from 15 to 100 keV are shown to be consistent with previous observations of these galaxies. It is noted that NGC 5128 rose in intensity from 1972 to 1975, that spectral softening occurred after early 1973, and that the source has since decreased in intensity while maintaining an E to the -1.7 photon power law. The results for NGC 4151 indicate variable absorption below 10 keV and a power-law slope of about E to the -1.4 in the range from 10 keV to 10 MeV.

  19. High-resolution X-ray spectroscopy of four active galaxies - Probing the intercloud medium

    NASA Technical Reports Server (NTRS)

    Lum, Kenneth S. K.; Canizares, Claude R.; Markert, Thomas H.; Arnaud, Keith A.

    1990-01-01

    The focal plane crystal spectrometer (FPCS) on the Einstein Observatory has been used to perform a high-resolution spectroscopic search for oxygen X-ray line emission from four active galaxies: Fairall 9, Mrk 421, Mrk 501, and PKS 0548 - 322. Specifically, O VIII Ly-alpha and Ly-beta, whose unredshifted energies are 653 and 775 eV, respectively, were sought. No narrow-line emission was detected within the energy bands searched. Upper limits are calculated on the line flux from these sources of 30 eV equivalent width and use a photoionization model to place corresponding upper limits on the densities of diffuse gas surrounding the active nuclei. The upper limits on gas density range from about 0.02-50/cu cm and probe various radial distances from the central source. This is the first time high-resolution X-ray spectroscopy has been used to place constraints on the intercloud medium in active galaxies.

  20. High-resolution X-ray spectroscopy of four active galaxies - Probing the intercloud medium

    NASA Astrophysics Data System (ADS)

    Lum, Kenneth S. K.; Canizares, Claude R.; Markert, Thomas H.; Arnaud, Keith A.

    1990-07-01

    The focal plane crystal spectrometer (FPCS) on the Einstein Observatory has been used to perform a high-resolution spectroscopic search for oxygen X-ray line emission from four active galaxies: Fairall 9, Mrk 421, Mrk 501, and PKS 0548 - 322. Specifically, O VIII Ly-alpha and Ly-beta, whose unredshifted energies are 653 and 775 eV, respectively, were sought. No narrow-line emission was detected within the energy bands searched. Upper limits are calculated on the line flux from these sources of 30 eV equivalent width and use a photoionization model to place corresponding upper limits on the densities of diffuse gas surrounding the active nuclei. The upper limits on gas density range from about 0.02-50/cu cm and probe various radial distances from the central source. This is the first time high-resolution X-ray spectroscopy has been used to place constraints on the intercloud medium in active galaxies.

  1. Energy Feedback from X-ray Binaries in the Early Universe

    NASA Technical Reports Server (NTRS)

    Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

    2013-01-01

    X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

  2. High-energy x-ray imaging spectrometer (HEXIS)

    NASA Astrophysics Data System (ADS)

    Matteson, James L.; Gruber, Duane E.; Heindl, William A.; Pelling, Michael R.; Peterson, Laurence E.; Rothschild, Richard E.; Skelton, Robert E.; Hink, Paul L.; Slavis, Kimberly R.; Binns, W. Robert

    1998-11-01

    HEXIS is a MIDEX-class mission concept for x-ray astronomy. Its objectives are to improve our knowledge of the high energy x-ray sky by increasing the number of sources above 20 keV to > 2,000, discovering transient sources such as x-ray novae and gamma-ray bursts, and making spectral and temporal studies of the sources. With mission life > 3 years, a 1-year all-sky survey sensitivity of approximately 0.3 mCrab, and continuous monitoring of the entire visible sky, HEXIS will provide unprecedented capabilities. Source positions will be determined to accuracies of a few arcmin or better. Spectra will be determined with an energy resolution of a few keV and source variability will be studied on time scales from < 1 sec to years. In addition, 10 times more sensitive studies of limited fields will be performed at the same time. Gamma-ray bursts will be detected about 4 times/week at about the same sensitivity as BATSE and the sensitivity to nova-like x-ray transients will be approximately 6 mCrab in one day. HEXIS contains a set of coded mask imagers that use position-sensitive CZT detectors operating from approximately 5 keV to 200 keV. Detector planes are built with 41 cm(superscript 2) CZT detector modules which employ crossed-strip readout to obtain a pixel size of 0.5 mm. Nine modules are grouped in a 369 cm(superscript 2) array for each imager. In the past 2 years significant progress has been made on techniques requires for HEXIS: position-sensitive CZT detectors and ASIC readout, coded mask imaging, and background properties at balloon altitudes. Scientific and technical details of HEXIS are presented together with result form tests of detectors and a coded mask imager.

  3. Studies of dark energy with X-ray observatories.

    PubMed

    Vikhlinin, Alexey

    2010-04-20

    I review the contribution of Chandra X-ray Observatory to studies of dark energy. There are two broad classes of observable effects of dark energy: evolution of the expansion rate of the Universe, and slow down in the rate of growth of cosmic structures. Chandra has detected and measured both of these effects through observations of galaxy clusters. A combination of the Chandra results with other cosmological datasets leads to 5% constraints on the dark energy equation-of-state parameter, and limits possible deviations of gravity on large scales from general relativity.

  4. Studies of dark energy with x-ray observatories

    PubMed Central

    Vikhlinin, Alexey

    2010-01-01

    I review the contribution of Chandra X-ray Observatory to studies of dark energy. There are two broad classes of observable effects of dark energy: evolution of the expansion rate of the Universe, and slow down in the rate of growth of cosmic structures. Chandra has detected and measured both of these effects through observations of galaxy clusters. A combination of the Chandra results with other cosmological datasets leads to 5% constraints on the dark energy equation-of-state parameter, and limits possible deviations of gravity on large scales from general relativity. PMID:20404207

  5. Refractive optical elements and optical system for high energy x-ray microscopy

    SciTech Connect

    Simon, M.; Altapova, V.; Baumbach, T.; Kluge, M.; Last, A.; Marschall, F.; Mohr, J.; Nazmov, V.; Vogt, H.

    2012-05-17

    In material science, X-ray radiation with photon energies above 25 keV is used because of its penetration into high density materials. Research of the inner structure of novel materials, such as electrodes in high power batteries for engines, require X-ray microscopes operating in the hard X-ray energy range. A flexible X-ray microscope for hard X-rays with photon energies higher than 25 keV will be realized at the synchrotron source ANKA in Karlsruhe, Germany. The device will use refractive X-ray lenses as condenser as well as objective lenses.

  6. X-ray and Sunyaev-Zel'Dovich properties of the warm-hot intergalactic medium

    SciTech Connect

    Ursino, E.; Galeazzi, M.; Huffenberger, K.

    2014-07-01

    We use numerical simulations to predict the soft X-ray ([0.4-0.6] keV) and Sunyaev-Zel'dovich (SZ) signal (at 150 GHz) from a large-scale structure in the universe and then compute two-point statistics to study the spatial distribution and time evolution of the signals. The average X-ray signal predicted for the warm-hot intergalactic medium (WHIM) is in good agreement with observational constraints that set it at about 10% of the total diffuse X-ray background. The characteristic angle computed with the autocorrelation function is of the order of some arcminutes and becomes smaller at higher redshift. The power spectrum peak of the SZ due to the WHIM is at l ∼ 10,000 and has an amplitude of ∼0.2 μK{sup 2}, about one order of magnitude below the signal measured with telescopes like Planck, Atacama Cosmology Telescope, and South Pole Telescope. Even if the high-redshift WHIM signal is too weak to be detected using X-rays only, the small-scale correlation between X-ray and SZ maps is dominated by the high-redshift WHIM. This makes the analysis of the SZ signal in support of X-rays a promising tool to study the early time WHIM.

  7. High resolution, multiple-energy linear sweep detector for x-ray imaging

    DOEpatents

    Perez-Mendez, Victor; Goodman, Claude A.

    1996-01-01

    Apparatus for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels.

  8. High resolution, multiple-energy linear sweep detector for x-ray imaging

    DOEpatents

    Perez-Mendez, V.; Goodman, C.A.

    1996-08-20

    Apparatus is disclosed for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels. 12 figs.

  9. X-ray scatter correction for dual-energy x-ray absorptiometry: compensation of patient's lean/fat composition

    NASA Astrophysics Data System (ADS)

    Dinten, Jean-Marc; Darboux, Michel; Bordy, Thomas; Robert-Coutant, Christine; Gonon, Georges

    2004-05-01

    At CEA-LETI, a DEXA approach for systems using a digital 2D radiographic detector has been developed. It relies on an original X-rays scatter management method, based on a combined use of an analytical model and of scatter calibration data acquired through different thicknesses of Lucite slabs. Since Lucite X-rays interaction properties are equivalent to fat, the approach leads to a scatter flux map representative of a 100% fat region. However, patients" soft tissues are composed of lean and fat. Therefore, the obtained scatter map has to be refined in order to take into account the various fat ratios that can present patients. This refinement consists in establishing a formula relating the fat ratio to the thicknesses of Low and High Energy Lucite slabs leading to same signal level. This proportion is then used to compute, on the basis of X-rays/matter interaction equations, correction factors to apply to Lucite equivalent X-rays scatter map. Influence of fat ratio correction has been evaluated, on a digital 2D bone densitometer, with phantoms composed of a PVC step (simulating bone) and different Lucite/water thicknesses as well as on patients. The results show that our X-rays scatter determination approach can take into account variations of body composition.

  10. Energy dispersive x-ray fluorescence analyzer with several x-ray tubes

    NASA Astrophysics Data System (ADS)

    Borisov, G. I.; Kondratenko, R. I.; Mikhin, V. A.; Odinov, B. V.; Pukhov, A. V.

    2005-07-01

    X-ray flurescent analyzer (XFA) has been developed and fabricated for determining sulphur, vanadium and nickel in oil. The instrument is equipped with three x-ray tubes with transmission Ti, Cu and Ag anodes, and aluminum, copper, and germanium filters, respectively, and one common switchable power supply. To excite characteristic radiation of determined elements, the characteristic radiation of the tube anode (titan, copper) is used, or the charactersitic radiation of the filter (germanium). XFA is fitted with one small-size electrically cooled semiconductor detector. The measuring device is based on a wide-angle geometry of characteristic radiation excitation and registration, where the x-ray tube focus illuminates the sample, and the registering detector 'sees' the illuminated area within the plane angle of 90° (it corresponds to 0.146 of 4p). Under such geometry, the dependence of the count rate for excited characteristic photons on the position of sample under study has a smooth maximum in the calculated sample position point. For one, the rate count changes by less than 1%. Quantitative results are obtained through the regression method. The instrument underwent metrology testing. It is designed for operation both in the laboratory and industrial environment. The instrument has been delivered for operation to the "Druzhba" pipeline.

  11. Radiosensitization of high-Z compounds by medium-energy 160 kV vs. high-energy 6 MV X-rays for radiation therapy: Theoretical, in vitro and in vivo studies of platinum compounds activating glioma F98 cancer cells

    NASA Astrophysics Data System (ADS)

    Lim, S.; Pradhan, A.; Nahar, S.; Montenegro, M.; Barth, R.; Nakkula, R.; Turro, C.

    2013-03-01

    Energy dependence of X-ray irradiation of high-Z compounds for enhanced radiosensitization is explored thoeretically and via in vitro and in vivo experiments. The cell killing ability of medium-energy X-rays from 160 kV source are found to be more effective than 6 MV X-rays in activating high-Z contrast agents. Results are presented for a newly synthesized Pt compound, Pyridine Terpyridine Pt(II) Nitrate ([Pt(typ)(py)]) and carboplatin in treating F98 rat glioma. In-vitro results show considerable reduction in cell viability for radiosensitized cells irradiated with a 160 kV irradiator. Cells treated with 6 MV LINAC radiation find little variation with radiation dose. Maximum dose enhancement factors (DEFs) and minimum cancer cell survival fractions correspond to 50-200 keV range, and fall rapidly at higher energies. Theoretical calculations of photoelectric absorption vis-a-vis total scattering demonstrates this energy dependence. However, in vivo studies of rats treated with [Pt(tpy)(py)] had a severe negative neurotoxic response, confirmed by histopathological analysis. But subsequent in vivo studies using carboplatin showed very positive results in the treatment of F98 glioma bearing rats and potential clinical radiation therapy.

  12. Dimensionality and noise in energy selective x-ray imaging

    PubMed Central

    Alvarez, Robert E.

    2013-01-01

    Purpose: To develop and test a method to quantify the effect of dimensionality on the noise in energy selective x-ray imaging. Methods: The Cramèr-Rao lower bound (CRLB), a universal lower limit of the covariance of any unbiased estimator, is used to quantify the noise. It is shown that increasing dimensionality always increases, or at best leaves the same, the variance. An analytic formula for the increase in variance in an energy selective x-ray system is derived. The formula is used to gain insight into the dependence of the increase in variance on the properties of the additional basis functions, the measurement noise covariance, and the source spectrum. The formula is also used with computer simulations to quantify the dependence of the additional variance on these factors. Simulated images of an object with three materials are used to demonstrate the trade-off of increased information with dimensionality and noise. The images are computed from energy selective data with a maximum likelihood estimator. Results: The increase in variance depends most importantly on the dimension and on the properties of the additional basis functions. With the attenuation coefficients of cortical bone, soft tissue, and adipose tissue as the basis functions, the increase in variance of the bone component from two to three dimensions is 1.4 × 103. With the soft tissue component, it is 2.7 × 104. If the attenuation coefficient of a high atomic number contrast agent is used as the third basis function, there is only a slight increase in the variance from two to three basis functions, 1.03 and 7.4 for the bone and soft tissue components, respectively. The changes in spectrum shape with beam hardening also have a substantial effect. They increase the variance by a factor of approximately 200 for the bone component and 220 for the soft tissue component as the soft tissue object thickness increases from 1 to 30 cm. Decreasing the energy resolution of the detectors increases the

  13. RADIO GALAXY FEEDBACK IN X-RAY-SELECTED GROUPS FROM COSMOS: THE EFFECT ON THE INTRACLUSTER MEDIUM

    SciTech Connect

    Giodini, S.; Finoguenov, A.; Boehringer, H.; Pierini, D.; Smolcic, V.; Massey, R.; BIrzan, L.; Zamorani, G.; Oklopcic, A.; Pratt, G. W.; Koekemoer, A. M.; Salvato, M.; Sanders, D. B.; Kartaltepe, J. S.; Thompson, D.

    2010-05-01

    We quantify the importance of the mechanical energy released by radio galaxies inside galaxy groups. We use scaling relations to estimate the mechanical energy released by 16 radio-active galactic nuclei located inside X-ray-detected galaxy groups in the COSMOS field. By comparing this energy output to the host groups' gravitational binding energy, we find that radio galaxies produce sufficient energy to unbind a significant fraction of the intragroup medium. This unbinding effect is negligible in massive galaxy clusters with deeper potential wells. Our results correctly reproduce the breaking of self-similarity observed in the scaling relation between entropy and temperature for galaxy groups.

  14. X-ray Reflectivity Measurements of Nanoscale Structures: Limits of the Effective Medium Approximation

    SciTech Connect

    Lee, Hae-Jeong; Soles, Christopher L.; Kang, Shuhui; Wook Ro, Hyun; Lin, Eric K.; Wu, Wen-li

    2007-09-26

    Specular X-ray reflectivity (SXR) can be used, in the limit of the effective medium approximation (EMA), as a high-resolution shape metrology for periodic patterns on a smooth substrate. The EMA means that the density of the solid patterns and the spaces separating the periodic patterns are averaged together. In this limit the density profile as a function of pattern height obtained by SXR can be used to extract quantitative pattern profile information. Here we explore the limitations of SXR as a pattern shape metrology by studying a series of linear grating structures with periodicities ranging from 300 nm to 16 {mu}m and determining at which length scales the EMA breaks down. We also study the angular dependence of the grating orientation with respect to the incident X-ray beam. The gratings systematically are rotated through a series of azimuthal angles with the incident X-ray beams ranging from 0 deg. to 90 deg. . The applicability of the EMA is related to the coherence length of the X-ray source. When the coherence length of beam is larger than the physical dimension of grating periodicities, EMA can be applied for characterizing nanostructures. For our slit-collimated X-ray source, the coherence length in the direction parallel to the long axis of the slit is on the order of 900 nm while the coherence length along the main axis of the beam appears to be in the range of (22 to 26) {mu}m.

  15. Energy-dispersive small-angle X-ray scattering with cone collimation using X-ray capillary optics

    NASA Astrophysics Data System (ADS)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi

    2016-09-01

    Energy-dispersive small-angle X-ray scattering (ED-SAXS) with an innovative design of cone collimation based on an ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL) had been explored. Using this new cone collimation system, scattering angle 2θ has a theoretical minimum angle related to the mean half-opening angle of the hollow cone beam of 1.42 mrad, and with the usable X-ray energy ranging from 4 to 30 keV, the resulting observable scattering vector q is down to a minimum value of about 0.003 Å-1 (or a Bragg spacing of about 2100 Å). However, the absorption of lower energies by X-ray capillary optics, sample transmission, and detector response function limits the application range to lower energy. Cone collimation ED-SAXS experiments carried out on pure water, Lupolen, and in situ temperature-dependent measurement of diacetylenic acid/melamine micelle solid were presented at three different scattering angles 2θ of 0.18°, 0.70° and 1.18° to illustrate the new opportunities offered by this technique as well as its limitations. Also, a comparison has been made by replacing the PPXRL with a pinhole, and the result shows that cone collimation ED-SAXS based on ESBC with PPXRL was helpful in improving the signal-to-noise ratio (i.e., reducing the parasitic background scattering) than ESBC with a pinhole. The cone collimation instrument based on X-ray capillary optics could be considered as a promising tool to perform SAXS experiments, especially cone collimation ED-SAXS has potential application for the in situ temperature-dependent studying on the kinetics of phase transitions.

  16. X-Ray Constraints on the Warm-Hot Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Kuntz, K. D.; Snowden, S. I.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Three observational constraints can be placed on a warm-hot intergalactic medium (WHIM) using ROSAT Position Sensitive Proportional Counter (PSPC) pointed and survey data, the emission strength, the energy spectrum, and the fluctuation spectrum. The upper limit to the emission strength of the WHIM is 7.5 +/- 1.0 keV/(s*sq cm*sr*keV) in the 3/4 keV band, an unknown portion of which value may be due to our own Galactic halo. The spectral stape of the WHIM emission can be described as thermal emission with logT = 6.42, although the true spectrum is more likely to come from a range of temperatures. The values of emission strength and spectral shape are in reasonable agreement with hydrodynamical cosmological models. The autocorrelation function in the 0.44 keV < E < 1.21 keV band range, w(theta), for the extragalactic soft X-ray background (SXRB) which includes both the WHIM and contributions due to point sources, is approx. < 0.002 for 10 min < 0 < 20 min in the 3/4 keV band. This value is lower than the Croft et al. (2000) cosmological model by a factor of approx. 5, but is still not inconsistent with cosmological models. It is also found that the normalization of the extragalactic power law component of the soft X-ray background spectrum must be 9.5 +/- 0.9 keV/(s*sq cm*sr*keV) to be consistent with the ROSAT All-Sky Survey.

  17. A model for multi-energy x-ray analysis.

    PubMed

    Midgley, S M

    2011-05-21

    Multi-energy x-ray analysis (MEXA) uses measurements of the x-ray linear attenuation coefficient μ, obtained at different photon energies to determine parameters that characterize the density and composition of materials. The key to achieving this goal is an accurate parameterization for μ, allowing measurements to be written as simultaneous equations and then solved. This author has reported such a model where mixtures are characterized by four or more statistical moments that describe the distribution of atomic number. These can be re-expressed as the product of the electron density N(e) and four or more compositional ratios R(k) with the same 'units' as atomic number (i.e. dimensionless). The model was turned to MEXA where it delivered reliable estimates for N(e) and R(4) and not the intermediate compositional ratios. This report studies the relationships between compositional ratios for tissues and tissue substitute materials. Correlations are identified leading to a new parameterization that is expressed as a nonlinear function of N(e), R(4) and other coefficients. The properties of the transformed parameterizations for μ and the energy absorption coefficient μ(en) are considered for low atomic number materials at energies 15-100 keV, and for a broader range of materials at energies 5 keV to 20 MeV. The interpretation of the parameters N(e) and R(4) is explored in terms of basis materials. The general case of three basis materials cannot be solved for all contributions, but the special case of just two basis materials can be fully solved.

  18. Low-energy shelf response in thin energy-dispersive X-ray detectors from Compton scattering of hard X-rays

    NASA Astrophysics Data System (ADS)

    Michel-Hart, N.; Elam, W. T.

    2017-08-01

    Silicon drift detectors have been successfully employed in both soft and hard X-ray spectroscopy. The response function to incident radiation at soft X-ray levels has been well studied and modeled, but less research has been published on response functions for these detectors to hard X-ray input spectra above 20 keV. When used with hard X-ray sources a significant low energy, non-peak response exists which can adversely affect detection limits for lighter elements in, for example, X-ray fluorescence spectroscopy. We present a numerical model that explains the non-peak response function of silicon drift detectors to hard X-rays based on incoherent Compton scattering within the detector volume. Experimental results are presented and numerically compared to model results.

  19. 30-Lens interferometer for high-energy X-rays.

    PubMed

    Lyubomirskiy, Mikhail; Snigireva, Irina; Kohn, Victor; Kuznetsov, Sergey; Yunkin, Vyacheslav; Vaughan, Gavin; Snigirev, Anatoly

    2016-09-01

    A novel high-energy multi-lens interferometer consisting of 30 arrays of planar compound refractive lenses is reported. Under coherent illumination each lens array creates a diffraction-limited secondary source. Overlapping such coherent beams produces an interference pattern demonstrating strong longitudinal functional dependence. The proposed multi-lens interferometer was tested experimentally at the 100 m-long ID11 ESRF beamline in the X-ray energy range from 30 to 65 keV. The interference pattern generated by the interferometer was recorded at fundamental and fractional Talbot distances. An effective source size (FWHM) of the order of 15 µm was determined from the first Talbot image, proving the concept that the multi-lens interferometer can be used as a high-resolution tool for beam diagnostics.

  20. The soft X-ray diffuse background and the structure of the local interstellar medium

    NASA Technical Reports Server (NTRS)

    Fried, P. M.; Nousek, J. A.; Sanders, W. T.; Kraushaar, W. L.

    1980-01-01

    Data from five rocket flights of the Wisconsin soft X-ray sky survey, covering the southern galactic hemisphere with 6.5 deg spatial resolution between 0.1 and 2.0 keV, are presented as intensity maps. Analysis of the data in two energy bands below 0.3 keV is presented here. These low-energy X-rays appear to be emitted from a plasma of about one-million K, the bulk of which is closer to the sun than even the nearest 5 x 10 to the 19th/sq cm of neutral gas. No evidence is found for the presence of nearby small (radius of about 0.6 pc) clouds of cool neutral gas, as has been proposed by McKee and Ostriker (1977). The X-ray measurements are consistent with the small amounts of local neutral material inferred from Lyman-alpha absorption measurements.

  1. Fluctuation x-ray microscopy for measuring medium-range order.

    SciTech Connect

    Fan, L.; McNulty, I.; Paterson, D.; Treacy, M. M. J.; Gibson, J. M.; Arizona State Univ.

    2005-01-01

    Many x-ray techniques exist to probe long- and short-range order in matter, in real space by imaging and in reciprocal space by diffraction and scattering. However, measuring medium-range order (MRO) in disordered materials is a long-standing problem. Based on fluctuation electron microscopy, which was applied successfully to the understanding of MRO in amorphous materials, we have developed fluctuation x-ray microscopy (FXM). This novel approach offers quantitative insight into medium-range correlations in materials at nanometer and larger length scales. It examines spatially resolved fluctuations in the intensity of a series of x-ray speckle patterns. The speckle variance depends on higher order correlations that are more sensitive to MRO. Systematically measuring the speckle variance as function of the momentum transfer and x-ray illumination size produces a fluctuation map that contains information about the degree of MRO and the correlation length. This approach can be used for the exploration of MRO and subtle spatial structural changes in a wide range of disordered materials from soft condensed matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials. It will also help us to understand the mechanisms of order-disorder transitions and may lead to control of ordering, which is important in developing ordered structures tailored for particular applications. A theory for FXM and preliminary experimental results from polystyrene latex spheres are discussed in this paper.

  2. High energy X-ray phase and dark-field imaging using a random absorption mask.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-28

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  3. High-Energy X-Ray Diffraction Analysis Tool

    SciTech Connect

    2011-11-29

    The functionality of heRXD includes the following: distance and angular calibration and viewing flat-panel detector images used for X-ray diffraction; image (polar) rebinning or "caking"; line position fitting in powder diffraction images; image segmentation or "blob finding"; crystal orentation indesing; and lattice vector refinement. These functionalities encompass a critical set analyzing teh data for high-energy diffraction measurements that are currently performed at synchrotron sources such as the Advanced Photon Source (APS). The software design modular and open source under LGPL. The intent is to provide a common framework and graphical user interface that has the ability to utillize internal as well as external subroutines to provide various optins for performing the fuctionalities listed above. The software will initially be deployed at several national user facilities--including APS, ALS, and CHESS--and then made available for download using a hosting service such as sourceforge.

  4. Focusing high-energy x rays by compound refractive lenses.

    PubMed

    Snigirev, A; Kohn, V; Snigireva, I; Souvorov, A; Lengeler, B

    1998-02-01

    Compound lenses made from low-Z materials (e.g., Be, B, C, and Al) set up as a linear array of refractive lenses are proposed for submicrometer focusing of high-energy x rays (>5 keV) in one or two dimensions. A theory of focusing based on Maxwell's equation and the Fresnel-Kirchhoff approach is presented. Compound refractive lenses were manufactured by drilling into an Al block a linear array of 200 closely spaced holes 0.5 mm in diameter for linear focusing and two crossed arrays of 100 holes each for point focusing. Focal spots of 3.7 mum and 8 mum x 18 mum were obtained at 30 keV for linear and two-dimensional lenses, respectively. Different technologies of manufacturing and possible applications of the proposed lenses are discussed.

  5. 30-lens interferometer for high energy x-rays

    SciTech Connect

    Lyubomirskiy, M. Snigireva, I. Vaughan, G.; Kohn, V.; Kuznetsov, S.; Yunkin, V.; Snigirev, A.

    2016-07-27

    We report a hard X-ray multilens interferometer consisting of 30 parallel compound refractive lenses. Under coherent illumination each CRL creates a diffraction limited focal spot - secondary source. An overlapping of coherent beams from these sources resulting in the interference pattern which has a rich longitudinal structure in accordance with the Talbot imaging formalism. The proposed interferometer was experimentally tested at ID11 ESRF beamline for the photon energies 32 keV and 65 keV. The fundamental and fractional Talbot images were recorded with the high resolution CCD camera. An effective source size in the order of 15 µm was determined from the first Talbot image proving that the multilens interferometer can be used as a high resolution beam diagnostic tool.

  6. Spatial resolution of synchrotron x-ray microtomography in high energy range: Effect of x-ray energy and sample-to-detector distance

    NASA Astrophysics Data System (ADS)

    Seo, D.; Tomizato, F.; Toda, H.; Uesugi, K.; Takeuchi, A.; Suzuki, Y.; Kobayashi, M.

    2012-12-01

    Spatial resolution of three-dimensional images obtained by synchrotron X-ray microtomography technique is evaluated using cyclic bar patterns machined on a steel wire. Influences of X-ray energy and the sample-to-detector distance on spatial resolution were investigated. High X-ray energies of 33-78 keV are applied due to the high X-ray absorption of transition metals. Best spatial resolution of about 1.2 μm pitch was observed at the sample-to-detector distance range of 20-110 mm and at the energy range of 68-78 keV. Several factors such as X-ray scattering and diffraction phenomena affecting the degradation of spatial resolution are also discussed.

  7. Reanalysis of X-ray emission from M87. 2: The multiphase medium

    NASA Technical Reports Server (NTRS)

    Tsai, John C.

    1994-01-01

    In a previous paper, we showed that a single-phase model for the gas around M87 simultaneously explained most available X-ray data. Total enclosed masses derived from the model, however, fell well below the determinations from optical measurements. In this paper, we consider possible solutions to the inconsistency, including two multiphase medium models for the gas and the consequences of systematic errors of the Einstein Focal Point Crystal Spectrometer (FPCS). First, we find that when constraints from optical mass determinations are not considered, the best-fit model to the X-ray data is always the single-phase model. Multiphase models or consideration of FPCS systematic errors are required only when optical mass constraints are included. We find that the cooling time model of White & Sarazin adequately explains the available X-ray data and predicts total masses which agree with optical measurements. An ad hoc power-law multiphase does not. This shows both that the existence of mass dropping out of the ambient phase is consistent with the data and that the cooling-time model gives a reasonable parameterization of the dropout rate. Our derived mass accretion rate is similar to previous determinations. The implications of this result for cluster mass determinations in general are discussed. We then consider 'self absorbing' models where we assume that material dropping out of the ambient medium goes completely into X-ray absorbing gas. The resulting internal absorption is small compared to Galactic absorption at most radii. The models are therefore indistinguishable from models with only Galactic absorption. We finally show that it is alternatively possible to simultaneously fit optical mass measurements and X-ray data with a single-phase model if some of the observed FPCS line fluxes are too high by the maximum systematic error. This possiblity can be checked with new data from satellites such as ASCA.

  8. Reanalysis of X-ray emission from M87. 2: The multiphase medium

    NASA Technical Reports Server (NTRS)

    Tsai, John C.

    1994-01-01

    In a previous paper, we showed that a single-phase model for the gas around M87 simultaneously explained most available X-ray data. Total enclosed masses derived from the model, however, fell well below the determinations from optical measurements. In this paper, we consider possible solutions to the inconsistency, including two multiphase medium models for the gas and the consequences of systematic errors of the Einstein Focal Point Crystal Spectrometer (FPCS). First, we find that when constraints from optical mass determinations are not considered, the best-fit model to the X-ray data is always the single-phase model. Multiphase models or consideration of FPCS systematic errors are required only when optical mass constraints are included. We find that the cooling time model of White & Sarazin adequately explains the available X-ray data and predicts total masses which agree with optical measurements. An ad hoc power-law multiphase does not. This shows both that the existence of mass dropping out of the ambient phase is consistent with the data and that the cooling-time model gives a reasonable parameterization of the dropout rate. Our derived mass accretion rate is similar to previous determinations. The implications of this result for cluster mass determinations in general are discussed. We then consider 'self absorbing' models where we assume that material dropping out of the ambient medium goes completely into X-ray absorbing gas. The resulting internal absorption is small compared to Galactic absorption at most radii. The models are therefore indistinguishable from models with only Galactic absorption. We finally show that it is alternatively possible to simultaneously fit optical mass measurements and X-ray data with a single-phase model if some of the observed FPCS line fluxes are too high by the maximum systematic error. This possiblity can be checked with new data from satellites such as ASCA.

  9. Characterization of Japanese color sticks by energy dispersive X-ray fluorescence, X-ray diffraction and Fourier transform infrared analysis

    NASA Astrophysics Data System (ADS)

    Manso, M.; Valadas, S.; Pessanha, S.; Guilherme, A.; Queralt, I.; Candeias, A. E.; Carvalho, M. L.

    2010-04-01

    This work comprises the use of energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques for the study of the composition of twentieth century traditional Japanese color sticks. By using the combination of analytical techniques it was possible to obtain information on inorganic and organic pigments, binders and fillers present in the sticks. The colorant materials identified in the sticks were zinc and titanium white, chrome yellow, yellow and red ochre, vermillion, alizarin, indigo, Prussian and synthetic ultramarine blue. The results also showed that calcite and barite were used as inorganic mineral fillers while Arabic gum was the medium used. EDXRF offered great potential for such investigations since it allowed the identification of the elements present in the sample preserving its integrity. However, this information alone was not enough to clearly identify some of the materials in study and therefore it was necessary to use XRD and FTIR techniques.

  10. Investigating Microphysics of Intracluster Medium with Advanced Hydrodynamic Simulations and X-Ray Observations

    NASA Astrophysics Data System (ADS)

    Markevitch, Maxim

    Clusters of galaxies are the largest virialized mass concentrations in the Universe, and have long been recognized as sensitive cosmological probes. It is becoming increasingly clear that to realize their full potential for cosmology, we need to drastically reduce uncertainties in the cluster mass estimates and their relation to various cluster observables that arise from our lack of knowledge of the microphysics of the intracluster medium (ICM). Such ICM properties as thermal conductivity, viscosity, strength and structure of the magnetic fields, the energy in the cosmic ray components and electron-ion equilibration rates are very uncertain. Each of these can have a significant impact on the cluster thermal balance and the quantities that we observe in the X-ray, SZ, and radio bands. Theoretical estimates of thermal conductivity and viscosity are particularly uncertain -- by orders of magnitude. The heat can be conducted only along the magnetic field lines, but by some estimates, even along the lines it can be effectively suppressed by small- scale field fluctuations. Even less understood is the physical nature and the magnitude of viscosity, which bears directly on the ICM heating and mixing processes and the damping of turbulence. We have identified a method to constrain these quantities by contrasting high-quality X-ray observations of merging clusters with our high-resolution magnetohydrodynamic simulations that would follow the evolution of the magnetic field and include various levels of anisotropic conduction and viscosity. Thermal conduction can best be constrained by comparing X-ray temperature maps for several well-observed merging clusters with the maps for their simulated analogs. The conduction at interesting levels is expected to erase any small-scale temperature nonuniformities on timescales comparable to that of the merger. Currently, the most readily observable effect of viscosity is the suppression of instabilities in the cluster `cold fronts

  11. High resolution energy-sensitive digital X-ray

    DOEpatents

    Nygren, David R.

    1995-01-01

    An apparatus and method for detecting an x-ray and for determining the depth of penetration of an x-ray into a semiconductor strip detector. In one embodiment, a semiconductor strip detector formed of semiconductor material is disposed in an edge-on orientation towards an x-ray source such that x-rays From the x-ray source are incident upon and substantially perpendicular to the front edge of the semiconductor strip detector. The semiconductor strip detector is formed of a plurality of segments. The segments are coupled together in a collinear arrangement such that the semiconductor strip detector has a length great enough such that substantially all of the x-rays incident on the front edge of the semiconductor strip detector interact with the semiconductor material which forms the semiconductor strip detector. A plurality of electrodes are connected to the semiconductor strip detect or such that each one of the of semiconductor strip detector segments has at least one of the of electrodes coupled thereto. A signal processor is also coupled to each one of the electrodes. The present detector detects an interaction within the semiconductor strip detector, between an x-ray and the semiconductor material, and also indicates the depth of penetration of the x-ray into the semiconductor strip detector at the time of the interaction.

  12. High resolution energy-sensitive digital X-ray

    DOEpatents

    Nygren, D.R.

    1995-07-18

    An apparatus and method for detecting an x-ray and for determining the depth of penetration of an x-ray into a semiconductor strip detector. In one embodiment, a semiconductor strip detector formed of semiconductor material is disposed in an edge-on orientation towards an x-ray source such that x-rays from the x-ray source are incident upon and substantially perpendicular to the front edge of the semiconductor strip detector. The semiconductor strip detector is formed of a plurality of segments. The segments are coupled together in a collinear arrangement such that the semiconductor strip detector has a length great enough such that substantially all of the x-rays incident on the front edge of the semiconductor strip detector interact with the semiconductor material which forms the semiconductor strip detector. A plurality of electrodes are connected to the semiconductor strip detector such that each one of the semiconductor strip detector segments has at least one of the of electrodes coupled thereto. A signal processor is also coupled to each one of the electrodes. The present detector detects an interaction within the semiconductor strip detector, between an x-ray and the semiconductor material, and also indicates the depth of penetration of the x-ray into the semiconductor strip detector at the time of the interaction. 5 figs.

  13. On the Detectability of CO Molecules in the Interstellar Medium via X-Ray Spectroscopy

    NASA Technical Reports Server (NTRS)

    Joachimi, Katerine; Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.

    2016-01-01

    We present a study of the detectability of CO molecules in the Galactic interstellar medium using high-resolution X-ray spectra obtained with the XMM-Newton Reflection Grating Spectrometer. We analysed 10 bright low mass X-ray binaries (LMXBs) to study the CO contribution in their line of sights. A total of 25 observations were fitted with the ISMabs X-ray absorption model which includes photoabsorption cross-sections for Oi, Oii, Oiii and CO. We performed a Monte Carlo (MC) simulation analysis of the goodness of fit in order to estimate the significance of the CO detection. We determine that the statistical analysis prevents a significant detection of CO molecular X-ray absorption features, except for the lines of sight towards XTE J1718-330 and 4U 1636-53. In the case of XTE J1817-330, this is the first report of the presence of CO along its line of sight. Our results reinforce the conclusion that molecules have a minor contribution to the absorption features in the O K-edge spectral region. We estimate a CO column density lower limit to perform a significant detection with XMM-Newton of N(CO) greater than 6 x 10(exp 16) per sq cm for typical exposure times.

  14. On the detectability of CO molecules in the interstellar medium via X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Joachimi, Katerine; Gatuzz, Efraín; García, Javier A.; Kallman, Timothy R.

    2016-09-01

    We present a study of the detectability of CO molecules in the Galactic interstellar medium using high-resolution X-ray spectra obtained with the XMM-Newton Reflection Grating Spectrometer. We analysed 10 bright low mass X-ray binaries (LMXBs) to study the CO contribution in their line of sights. A total of 25 observations were fitted with the ISMabs X-ray absorption model which includes photoabsorption cross-sections for O I, O II, O III and CO. We performed a Monte Carlo (MC) simulation analysis of the goodness of fit in order to estimate the significance of the CO detection. We determine that the statistical analysis prevents a significant detection of CO molecular X-ray absorption features, except for the lines of sight towards XTE J1718-330 and 4U 1636-53. In the case of XTE J1817-330, this is the first report of the presence of CO along its line of sight. Our results reinforce the conclusion that molecules have a minor contribution to the absorption features in the O K-edge spectral region. We estimate a CO column density lower limit to perform a significant detection with XMM-Newton of N(CO) > 6 × 1016 cm-2 for typical exposure times.

  15. High Resolution Spectroscopy of X-ray Quasars: Searching for the X-ray Absorption from the Warm-Hot Intergalactic Medium

    NASA Technical Reports Server (NTRS)

    Fang, Taotao; Canizares, Claude R.; Marshall, Herman L.

    2004-01-01

    We present a survey of six low to moderate redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the Warm-Hot Intergalactic Medium. All the X-ray spectra can be well fitted by a power law with neutral hydrogen absorption. Only one feature is detected at above 3-sigma level in all the spectra, which is consistent with statistic fluctuation. We discuss the implications in our understanding of the baryon content of the universe. We also discuss the implication of the non-detection of the local (z approx. 0) X-ray absorption.

  16. Formation and amplification of subfemtosecond x-ray pulses in a plasma medium of hydrogenlike ions with a modulated resonant transition

    NASA Astrophysics Data System (ADS)

    Akhmedzhanov, T. R.; Antonov, V. A.; Morozov, Anatoly; Goltsov, Alexander; Scully, Marlan; Suckewer, Szymon; Kocharovskaya, Olga

    2017-09-01

    Coherent intense attosecond x-ray pulses could lead to a fast dynamical imaging of biological macromolecules and other material nanostructures with a unique combination of a record high temporal and spatial resolution. Plasma-based x-ray laser sources are capable of producing high-energy x-ray pulses but with relatively long picosecond duration. The sources based on high-harmonic generation (HHG) of a laser field allow one to produce much shorter pulses but of lower energy. We suggest two different paths towards intense subfemtosecond x-ray sources: (i) via efficient transformation of the picosecond radiation of the x-ray plasma lasers into the trains of subfemtosecond pulses in a resonantly absorbing medium, and (ii) via amplification of HHG radiation in the active medium of the x-ray plasma lasers. We show that essentially the same technique can be used for realization of both paths. This technique is a modulation of the parameters of the resonant transition (accordingly in absorbing or amplifying medium) produced under the action of a sufficiently strong infrared or optical field. We propose experimental realization of the suggested technique in the passive and/or active media of (i) Li iii ions modulated by the mid-IR laser field and (ii) C vi ions modulated by the optical laser radiation.

  17. The effects of X-rays from active galactic nuclei on the interstellar medium of the surrounding galaxy

    NASA Technical Reports Server (NTRS)

    Begelman, Mitchell C.

    1988-01-01

    The effects of an active nucleus on the large-scale properties of the host galaxy are examined, focusing on the effects of X-ray heating on the host galaxy's interstellar medium. The basic properties of AGNs and several questions concerning AGNs are reviewed. The relationship between X-ray heated winds and coronae is outlined. The case of X-ray heated winds in type 2 Seyfert galaxies is discussed.

  18. Dual energy iodine contrast CT with monochromatic x-rays

    SciTech Connect

    Dilmanian, F.A.; Wu, X.Y.; Kress, J.

    1995-12-31

    Computed tomography (CT) with monochromatic x-ray beams was used to image phantoms and a live rabbit using the preclinical Multiple Energy Computed Tomography (MECT) system at the National Synchrotron Light Source. MECT has a horizontal fan beam with a subject apparatus rotating about a vertical axis. Images were obtained at 43 keV for single-energy studies, and at energies immediately below and above the 33.17 keV iodine K-edge for dual-energy subtraction CT. Two CdWO{sub 4}-photodiode array detectors were used. The high-resolution detector (0.5 mm pitch, uncollimated) provided 14 line pair/cm in-plane spatial resolution, with lower image noise than conventional CT. Images with the low-resolution detector (1.844-mm pitch, collimated to 0.922 mm detector elements) had a sensitivity for iodine of {approx} 60 {micro}g/cc in 11-mm channels inside a 135 mm-diameter acrylic cylindrical phantom for a slice height of 2.5 mm and a surface does of {approx} 4 cGy. The image noise was {approx} 1 Hounsfield Unit (HU); it was {approx} 3 HU for the same phantom imaged with conventional CT at approximately the same dose, slice height, and spatial resolution ({approx} 7 lp/cm). These results show the potential advantage of MECT, despite present technical limitations.

  19. Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy

    SciTech Connect

    Kojima, Sadaoki E-mail: sfujioka@ile.osaka-u.ac.jp; Ikenouchi, Takahito; Arikawa, Yasunobu; Sakata, Shohei; Zhang, Zhe; Abe, Yuki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke E-mail: sfujioka@ile.osaka-u.ac.jp; Azechi, Hiroshi; Ozaki, Tetsuo; Miyamoto, Shuji; Yamaguchi, Masashi; Takemoto, Akinori

    2016-04-15

    Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10{sup 13} photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO{sub 2} converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.

  20. Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy.

    PubMed

    Kojima, Sadaoki; Ikenouchi, Takahito; Arikawa, Yasunobu; Sakata, Shohei; Zhang, Zhe; Abe, Yuki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Ozaki, Tetsuo; Miyamoto, Shuji; Yamaguchi, Masashi; Takemoto, Akinori; Fujioka, Shinsuke; Azechi, Hiroshi

    2016-04-01

    Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10(13) photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO2 converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.

  1. Improved energy coupling into the gain region of the Ni-like Pd transient collisional x-ray laser

    SciTech Connect

    Smith, R; Dunn, J; Filevich, J; Moon, S; Nilsen, J; Keenan, R; Shlyaptsev, V; Rocca, J; Hunter, J; Shepherd, R; Booth, R; Marconi, M

    2004-10-05

    We present within this paper a series of experiments, which yield new observations to further our understanding of the transient collisional x-ray laser medium. We use the recently developed technique of picosecond x-ray laser interferometry to probe the plasma conditions in which the x-ray laser is generated and propagates. This yields two dimensional electron density maps of the plasma taken at different times relative to the peak of the 600ps plasma-forming beam. In another experimental campaign, the output of the x-ray laser plasma column is imaged with a spherical multilayer mirror onto a CCD camera to give a two-dimensional intensity map of the x-ray laser output. Near-field imaging gives insights into refraction, output intensity and spatial mode structure. Combining these images with the density maps gives an indication of the electron density at which the x-ray laser is being emitted at (yielding insights into the effect of density gradients on beam propagation). Experimental observations coupled with simulations predict that most effective coupling of laser pump energy occurs when the duration of the main heating pulse is comparable to the gain lifetime ({approx}10ps for Ni-like schemes). This can increase the output intensity by more than an order of magnitude relative to the case were the same pumping energy is delivered within a shorter heating pulse duration (< 3ps). We have also conducted an experiment in which the output of the x-ray laser was imaged onto the entrance slit of a high temporal resolution streak camera. This effectively takes a one-dimensional slice of the x-ray laser spatial profile and sweeps it in time. Under some conditions we observe rapid movement of the x-ray laser ({approx} 3 {micro}m/ps) towards the target surface.

  2. Energy-resolved X-ray imaging method with a counting-type pixel detector

    NASA Astrophysics Data System (ADS)

    Toyokawa, H.; Kajiwara, K.; Sato, M.; Kawase, M.; Honma, T.; Takagaki, M.

    2011-09-01

    We have developed an energy-resolved X-ray imaging method using the counting-type pixel detector PILATUS-100K. X-ray intensities were recorded as a scan of threshold energies, and the X-ray energy was determined by an s-curve fitting analysis. As a capability study of ultra precise energy-resolved imaging, X-ray beam intensities at 15.75, 15.76, 15.77, 15.78, 15.79, and 15.80 keV were measured and their threshold scan distributions could be clearly separated from each other. Laue diffraction patterns of a silicon steel sample were recorded with white X-ray beams. A grain image of silicon steel was obtained with a sample position scan. The reflected X-ray energy was also measured at three sample positions to analyze the lattice constant of the sample crystal grain.

  3. Superiority of Low Energy 160 KV X-Rays Compared to High Energy 6 MV X-Rays in Heavy Element Radiosensitization for Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Lim, Sara N.; Pradhan, Anil K.; Nahar, Sultana N.; Barth, Rolf F.; Yang, Weilian; Nakkula, Robin J.; Palmer, Alycia; Turro, Claudia

    2013-06-01

    High energy X-rays in the MeV range are generally employed in conventional radiation therapy from linear accelerators (LINAC) to ensure sufficient penetration depths. However, lower energy X-rays in the keV range may be more effective when coupled with heavy element (high-Z or HZ) radiosensitizers. Numerical simulations of X-ray energy deposition for tumor phantoms sensitized with HZ radiosensitizers were performed using the Monte Carlo code Geant4. The results showed enhancement in energy deposition to radiosensitized phantoms relative to unsensitized phantoms for low energy X-rays in the keV range. In contrast, minimal enhancement was seen using high energy X-rays in the MeV range. Dose enhancement factors (DEFs) were computed and showed radiosensitization only in the low energy range < 200 keV, far lower than the energy of the majority of photons in the LINAC energy range. In vitro studies were carried to demonstrate the tumoricidal effects of HZ sensitized F98 rat glioma cells following irradiation with both low energy 160 kV and high energy 6 MV X-ray sources. The platinum compound, pyridine terpyridine Pt(II) nitrate, was initially used because it was 7x less toxic that an equivalent amount of carboplatin in vitro studies. This would allow us to separate the radiotoxic and the chemotoxic effects of HZ sensitizers. Results from this study showed a 10-fold dose dependent reduction in surviving fractions (SF) of radiosensitized cells treated with low energy 160 kV X-rays compared to those treated with 6 MV X-rays. This is in agreement with our simulations that show an increase in dose deposition in radiosensitized tumors for low energy X-rays. Due to unforeen in vivo toxicity, however, another in vitro study was performed using the commonly used, Pt-based chemotherapeutic drug carboplatin which confirmed earlier results. This lays the ground work for a planned in vivo study using F98 glioma bearing rats. This study demonstrates that while high energy X-rays are

  4. Determining the Grain Composition of the Interstellar Medium with High-Resolution X-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Julia C.; Ravel, B.

    2005-04-01

    We investigate the ability of high-resolution X-ray spectroscopy to directly probe the grain composition of the interstellar medium. Using iron K-edge experimental data of likely ISM dust candidates taken at the National Synchrotron Light Source at Brookhaven National Laboratory and the Advanced Photon Source at Argonne National Laboratory, we explore the prospects for determining the chemical composition of astrophysical dust and discuss a technique for doing so. Focusing on the capabilities of the Astro-E2 XRS microcalorimeters, we assess the limiting effects of spectral resolution and noise for detecting significant X-ray absorption fine structure signal in astrophysical environments containing dust. We find that given sufficient signal, the resolution of the XRS will allow us to definitively distinguish gas-phase from dust-phase absorption and certain chemical compositions.

  5. Formation and evolution of X-ray clusters - A hydrodynamic simulation of the intracluster medium

    SciTech Connect

    Evrard, A.E. )

    1990-11-01

    The thermodynamic history of the hot intracluster medium in a cluster of Coma richness was examined using a numerical simulation incorporating three-dimensional hydrodynamics of a collisional baryonic component within a self-consistently evolving dark matter mass distribution. The model evolves to states at low redshifts whose X-ray and optical properties are strikingly similar to Coma and A2256. The elliptical X-ray isophotes seen at z = 0 are remnants of a merger event which occurred at z = 0.2; thus, Coma and A2256 probably suffered moderate merger events in the recent past. The model also indicates that clusters of Coma richness should display a Suniaev-Zel'dovich central decrement of about 0.5 mK. 70 refs.

  6. An edge-on charge-transfer design for energy-resolved x-ray detection

    NASA Astrophysics Data System (ADS)

    Shi, Zaifeng; Yang, Haoyu; Cong, Wenxiang; Wang, Ge

    2016-06-01

    As an x-ray beam goes through the human body, it will collect important information via interaction with tissues. Since this interaction is energy-sensitive, the state-of-the-art spectral CT technologies provide higher quality images of biological tissues with x-ray energy information (or spectral information). With existing energy-integrating technologies, a large fraction of energy information is ignored in the x-ray detection process. Although the recently proposed photon-counting technology promises to achieve higher image quality at a lower radiation dose, it suffers from limitations in counting rate, performance uniformity, and fabrication cost. In this paper, we focus on an alternative approach to resolve the energy distribution of transmitted x-ray photons. First, we analyze the x-ray attenuation in a silicon substrate and describe a linear approximation model for x-ray detection. Then, we design an edge-on architecture based on the proposed energy-resolving model. In our design, the x-ray-photon-induced charges are transferred sequentially resembling the working process of a CCD camera. Finally, we numerically evaluate the linear approximation of x-ray attenuation and derive the energy distribution of x-ray photons. Our simulation results show that the proposed energy-sensing approach is feasible and has the potential to complement the photon-counting technology.

  7. An edge-on charge-transfer design for energy-resolved x-ray detection.

    PubMed

    Shi, Zaifeng; Yang, Haoyu; Cong, Wenxiang; Wang, Ge

    2016-06-07

    As an x-ray beam goes through the human body, it will collect important information via interaction with tissues. Since this interaction is energy-sensitive, the state-of-the-art spectral CT technologies provide higher quality images of biological tissues with x-ray energy information (or spectral information). With existing energy-integrating technologies, a large fraction of energy information is ignored in the x-ray detection process. Although the recently proposed photon-counting technology promises to achieve higher image quality at a lower radiation dose, it suffers from limitations in counting rate, performance uniformity, and fabrication cost. In this paper, we focus on an alternative approach to resolve the energy distribution of transmitted x-ray photons. First, we analyze the x-ray attenuation in a silicon substrate and describe a linear approximation model for x-ray detection. Then, we design an edge-on architecture based on the proposed energy-resolving model. In our design, the x-ray-photon-induced charges are transferred sequentially resembling the working process of a CCD camera. Finally, we numerically evaluate the linear approximation of x-ray attenuation and derive the energy distribution of x-ray photons. Our simulation results show that the proposed energy-sensing approach is feasible and has the potential to complement the photon-counting technology.

  8. A versatile medium-resolution x-ray emission spectrometer for diamond anvil cell applications

    SciTech Connect

    Mortensen, D. R.; Seidler, G. T.; Bradley, J. A.; Lipp, M. J.; Evans, W. J.; Chow, P.; Xiao, Y.-M.; Boman, G.; Bowden, M. E.

    2013-08-15

    We present design and performance details for a polycapillary-coupled x-ray spectrometer that provides very high collection efficiency at a moderate energy resolution suitable for many studies of nonresonant x-ray emission spectroscopy, especially for samples of heavy elements under high pressures. Using a single Bragg analyzer operating close to backscattering geometry so as to minimize the effect of the weak divergence of the quasicollimated exit beam from the polycapillary optic, this instrument can maintain a typical energy resolution of 5 eV over photon energies from 5 keV to 10 keV. We find dramatically improved count rates as compared to a traditional higher-resolution instrument based on a single spherically bent crystal analyzer.

  9. Internal conversion in energy dispersive X-ray analysis of actinide-containing materials.

    PubMed

    Wiss, Thierry; Thiele, Hartmut; Cremer, Bert; Ray, Ian

    2007-06-01

    The use of X-ray elemental analysis tools like energy dispersive X-ray (EDS) is described in the context of the investigation of nuclear materials. These materials contain radioactive elements, particularly alpha-decaying actinides that affect the quantitative EDS measurement by producing interferences in the X-ray spectra. These interferences originating from X-ray emission are the result of internal conversion by the daughter atoms from the alpha-decaying actinides. The strong interferences affect primarily the L X-ray lines from the actinides (in the typical energy range used for EDS analysis) and would require the use of the M lines. However, it is typically at the energy of the actinide's M lines that the interferences are dominant. The artifacts produced in the X-ray analysis are described and illustrated by some typical examples of analysis of actinide-bearing material.

  10. Quality in dual-energy X-ray absorptiometry scans.

    PubMed

    Morgan, Sarah L; Prater, Ginnie L

    2017-11-01

    Dual-energy X-ray absorptiometry (DXA) is the gold standard for measuring bone mineral density (BMD), making the diagnosis of osteoporosis, and for monitoring changes in BMD over time. DXA data are also used in the determination of fracture risk. Procedural steps in DXA scanning can be broken down into scan acquisition, analysis, interpretation, and reporting. Careful attention to quality control pertaining to these procedural steps should theoretically be beneficial in patient management. Inattention to procedural steps and errors that may occur at each step has the possibility of providing information that would inform inappropriate clinical decisions, generating unnecessary healthcare expenses and ultimately causing avoidable harm to patients. This article reviews errors in DXA scanning that affect trueness and precision related to the machine, the patient, and the technologist and reviews articles which document problems with DXA quality in clinical and research settings. An understanding of DXA errors is critical for DXA quality; programs such as certification of DXA technologists and interpreters help in assuring quality bone densitometry. As DXA errors are common, pay for performance requiring DXA technologists and interpreters to be certified and follow quality indicators is indicated. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Technical principles of dual energy x-ray absorptiometry.

    PubMed

    Blake, G M; Fogelman, I

    1997-07-01

    Since its introduction nearly ten years ago, dual-energy x-ray absorptiometry (DXA) has become the single most widely used technique for performing bone densitometry studies. One reason for its popularity is the ability of DXA systems to measure bone mineral density (BMD) in the spine and proximal femur, the two most common sites for osteoporotic fractures. Other advantages of DXA include the exceptionally low radiation dose to patients, short scan times, high resolution images, good precision and inherent stability of calibration. For these reasons DXA scans are widely used to diagnose osteoporosis, assist making decisions in treatment, and as a follow-up response to therapy. Another important application has been the use of DXA in many clinical trials of new treatments for osteoporosis. Since the first generation pencil beam DXA systems became available, the most significant technical innovation has been the introduction of fan beam systems with shorter scan times, increased patient throughput, and improved image quality. New clinical applications include the measurement of lateral spine and total body BMD, body composition, and vertebral morphometry. Despite these advances, posteroanterior (PA) spine and proximal femur scans remain the most widely used application because of their utility in treatment decisions and monitoring response to therapy.

  12. The high energy transmission grating spectrometer for AXAF. [Advanced X-ray Astrophysics Facility

    NASA Technical Reports Server (NTRS)

    Canizares, C. R.; Schattenburg, M. L.; Smith, H. I.

    1986-01-01

    Attention is given to a high energy transmission grating spectrometer that operates over the range 0.4-8 keV, giving resolving powers of 100-1000 and effective areas of 10-200 sq cm. The instrument, which is part of the MIT high resolution X-ray spectroscopy investigation, consists of a single array of grating facets of two types: medium energy gratings of 0.6-micron period, 0.5-micron thick silver mounted behind the outer three AXAF mirrors, and high energy gratings of 0.2-micron period, 1.0-micron thick gold mounted behind the inner three mirrors. The gratings are oriented so as to correct for coma and so that the medium and high energy spectra form a shallow 'X' at the AXAF focal plane. Likely targets include normal stars, binary X-ray sources, active galactic nuclei and quasars. The HETGS can also be used to give moderate resolution spectra of slightly extended sources and monochromatic images of sources with strong lines, such as supernova remnants in nearby galaxies.

  13. X-ray and gamma-ray line production by nonthermal ions. [in interstellar medium

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Ramaty, R.; Omidvar, K.

    1978-01-01

    X-ray production at about 6.8 keV by the 2p to 1s transition in fast hydrogen- and helium-like iron ions is calculated, following both electron capture to excited levels and collisional excitation. A refinement of the Oppenheimer-Brinkman-Kramers (1930) approximation is used to obtain an improved charge-exchange cross-section. This, and the corresponding ionization cross section, were used to determine equilibrium charge fractions for iron ions as functions of their energy. The effective X-ray line production cross section was found to be sharply peaked in energy at about 8 to 12 MeV per amu. Since fast ions of similar energies can also excite nuclear levels, the ratio of selected strong gamma-rays line emissivities to the X-ray line emissivity is calculated. These calculations are employed to set limits on the intensity of gamma-rays line emission from the galactic center and the radio galaxy Cen A, and it is found that these limits are generally lower than those reported in the literature.

  14. Figure Measurements of High-Energy-X-Ray Replicated Optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Kester, Thomas; Engelhaupt, Darell; Speegle, Chet; Martin, Greg

    2003-01-01

    We are developing grazing incidence x-ray optics for a balloon-borne hard-x-ray telescope (HERO). The HERO mirror shells are fabricated using electroform-nickel replication off super-polished cylindrical mandrels. One of the sources for mirror resolution error is departure of the shell figure from prescription. We have modified a Vertical-scan Long Trace Profilometer (VLTP) in order to measure the figure of the inner surface of the HERO mirror shells for diameters as small as 76 mm. Mirror alignment method and sources for systematic errors will be discussed. Comparison of figure metrology of the mandrel and the shells will be presented together with results from x-ray tests.

  15. A medium sensitivity X-ray survey using the Einstein Observatory - The log N-log S relation for extragalactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Maccacaro, T.; Gioia, I. M.; Zamorani, G.; Feigelson, E. D.; Fener, M.; Giacconi, R.; Griffiths, R. E.; Murray, S. S.; Stocke, J.; Liebert, J.

    1982-01-01

    The paper presents results of an X-ray survey of about 50 sq deg of the high galactic latitude sky at sensitivities in the range of 7 x 10 to the -14 to 5 x 10 to the -12 ergs/sq cm/s. The number-flux relation is derived for the extragalactic population to yield a best-fit power-law slope of 1.53 + or - 0.16, and the content of the sample is analyzed in terms of types of sources, appearing to be significantly different from the content of similar samples selected at higher fluxes. The medium sensitivity sample of extragalactic sources is dominated by active galactic nuclei, while samples selected at higher fluxes and higher energies are dominated by clusters of galaxies. Thus, the number-flux relation for extragalactic sources may be interpreted to a first approximation as the sum of the two different distributions with flatter and steeper slopes describing clusters and AGNs, respectively.

  16. A Low-Energy X-Ray Irradiator for Electrophysiological Studies

    DTIC Science & Technology

    1988-12-01

    Radiation Protection and Measurements ( NCRP ) Report No. 49, "Structural Shielding Design and Evaluation for Medical Use of X-rays and Gamma Rays of Energies...tube while it operated within the shield. On the basis of these assumptions, the required shielding thicknesses derived from appendix C, table 8, of NCRP ...Figure 3. Lead-shielded Faraday cage: (a) closed view; (b) open view with x-ray tube in place. Note that the x-ray shielding parameters covered in NCRP

  17. Automatic detection of bone fragments in poultry using multi-energy x-rays

    SciTech Connect

    Gleason, Shaun S; Paulus, Michael J; Mullens, James A

    2002-04-09

    At least two linear arrays of x-ray detectors are placed below a conveyor belt in a poultry processing plant. Multiple-energy x-ray sources illuminate the poultry and are detected by the detectors. Laser profilometry is used to measure the poultry thickness as the x-ray data is acquired. The detector readout is processed in real time to detect the presence of small highly attenuating fragments in the poultry, i.e., bone, metal, and cartilage.

  18. Supernova SN 2014C X-ray

    NASA Image and Video Library

    2017-01-24

    This image from NASA's Chandra X-ray Observatory shows spiral galaxy NGC 7331, center, in a three-color X-ray image. Red, green and blue colors are used for low, medium and high-energy X-rays, respectively. An unusual supernova called SN 2014C has been spotted in this galaxy. http://photojournal.jpl.nasa.gov/catalog/PIA21089

  19. Methods for calculating X-ray diffuse scattering from a crystalline medium with spheroidal quantum dots

    NASA Astrophysics Data System (ADS)

    Punegov, V. I.; Sivkov, D. V.

    2015-03-01

    Two independent approaches to calculate the angular distribution of X-ray diffusion scattering from a crystalline medium with spheroidal quantum dots (QDs) have been proposed. The first method is based on the analytical solution involving the multipole expansion of elastic strain fields beyond QDs. The second approach is based on calculations of atomic displacements near QDs by the Green's function method. An analysis of the diffuse scattering intensity distribution in the reciprocal space within these two approaches shows that both methods yield similar results for the chosen models of QD spatial distribution.

  20. Carbon and oxygen X-ray line emission from the interstellar medium

    NASA Technical Reports Server (NTRS)

    Schnopper, H. W.; Delvaille, J. P.; Rocchia, R.; Blondel, C.; Cheron, C.; Christy, J. C.; Ducros, R.; Koch, L.; Rothenflug, R.

    1982-01-01

    A soft X-ray, 0.3-1.0 keV spectrum from a 1 sr region which includes a portion of the North Polar Spur, obtained by three rocketborne lithium-drifted silicon detectors, shows the C V, C VI, O VII and O VIII emission lines. The spectrum is well fitted by a two-component, modified Kato (1976) model, where the coronal emission is in collisional equilibrium, with interstellar medium and North Polar Spur temperatures of 1.1 and 3.8 million K, respectively.

  1. Carbon and oxygen X-ray line emission from the interstellar medium

    NASA Technical Reports Server (NTRS)

    Schnopper, H. W.; Delvaille, J. P.; Rocchia, R.; Blondel, C.; Cheron, C.; Christy, J. C.; Ducros, R.; Koch, L.; Rothenflug, R.

    1982-01-01

    A soft X-ray, 0.3-1.0 keV spectrum from a 1 sr region which includes a portion of the North Polar Spur, obtained by three rocketborne lithium-drifted silicon detectors, shows the C V, C VI, O VII and O VIII emission lines. The spectrum is well fitted by a two-component, modified Kato (1976) model, where the coronal emission is in collisional equilibrium, with interstellar medium and North Polar Spur temperatures of 1.1 and 3.8 million K, respectively.

  2. Optimal x-ray energy for digital mammography

    SciTech Connect

    Logan, C.M.; Hernandez, J.M.; Kinney, J.H.; Lewis, D.L.

    1992-11-01

    Screening mammography is a radiological procedure requiring the highest possible image quality at the lowest possible dose. It is widely recognized that digital image acquisition, computer assisted diagnosis, and scientific visualization can provide substantial improvement in mammography. For such systems, much of what is accepted as best practice with today`s film/screen/lightbox systems will become inappropriate. A complete system design is required. We have constructed a model of the breast imaging process. These results show that molybdenum-anode, molybdenum-filtered x-ray spectra are ill-suited for digital mammography. An x-ray spectrum rich in 22-to 25-keV photons is needed.

  3. Extension of x-ray imaging linear systems analysis to detectors with energy discrimination capability

    SciTech Connect

    Marchal, Julien P.

    2005-08-15

    A figure of merit, the broad-spectrum generalized detective quantum efficiency, which describes the performance of digital detectors designed for broad-spectrum x-ray imaging is derived from linear response theory. This measure of the imaging efficacy of an x-ray sensor is obtained when detector contrast modulation in the domain of x-ray energy is introduced in the Fourier-based analysis of digital systems. A method is proposed to scale existing figures of merit according to the energy-dependent response of the detector and the spectral shape of the x-ray beam. The new figure of merit obtained with this method provides an extended description of system performance when comparing energy-integrating, single-photon counting, and future energy-sensitive x-ray imaging sensors. The applicability of this linear system analysis is restricted to the tasks of low-contrast object detection in radiography. The method for scaling the figure of merit to take into consideration broad-spectrum conditions is applied to mammography for future energy-dependent detectors. An approximation valid in the typical mammographic x-ray energy range is used to calculate the broad-spectrum generalized detective quantum efficiency at zero spatial frequency, for several mammographic x-ray spectra. X-ray energy weighting in mammography is investigated in the context of simulated tumors and microcalcifications detection by comparing this figure of merit, calculated for different detector technologies, under ideal imaging conditions, at zero spatial frequency.

  4. Temporal evolution of an energetic electron population in an inhomogeneous medium: Application to solar hard X-ray bursts

    NASA Technical Reports Server (NTRS)

    Vilmer, N.; Mackinnon, A. L.; Trottet, G.

    1985-01-01

    Energetic electrons accelerated during solar flares can be studied through the hard X-ray emission they produce when interacting with the solar ambient atmosphere. In the case of the non thermal hard X-ray emission, the instanteous X-ray flux emitted at one point of the atmosphere is related to the instantaneous fast electron spectrum at that point. A hard X-ray source model then requires the understanding of the evolution in space and time of the fast particle distribution. The physical processes involved here are energy losses due to Coulomb collisions and pitch angle scattering due to both collisions and magnetic field gradients.

  5. Sun Shines in High-Energy X-rays

    NASA Image and Video Library

    2014-12-22

    X-rays stream off the sun in this first picture of the sun, overlaid on a picture taken by NASA Solar Dynamics Observatory SDO, taken by NASA NuSTAR. The field of view covers the west limb of the sun.

  6. A Review of X-ray Diagnostic Calibrations in the 2 to 100 keV Region Using the High Energy X-ray Calibration Facility (HEX)

    SciTech Connect

    Ali, Zaheer; Pond, T; Buckles, R A; Maddox, B R; Chen, C D; DeWald, E L; Izumi, N; Stewart, R

    2010-05-19

    The precise and accurate measurement of X-rays in the 2 keV to 100 keV region is crucial to the understanding of HED plasmas and warm dense matter in general. With the emergence of inertially confined plasma facilities as the premier platforms for ICF, laboratory astrophysics, and national security related plasma experiments, the need to calibrate diagnostics in the high energy X-ray regime has grown. At National Security Technologies High Energy X-ray Calibration Facility (HEX) in Livermore, California, X-ray imagers, filter-fluorescer spectrometers, crystal spectrometers, image plates, and nuclear diagnostics are calibrated. The HEX can provide measurements of atomic line radiation, X-ray flux (accuracy within 10%), and X-ray energy (accuracy within 1%). The HEX source is comprised of a commercial 160 kV X-ray tube, a fluorescer wheel, a filter wheel, and a lead encasement. The X-ray tube produces a Tungsten bremsstrahlung spectrum which causes a foil to fluoresce line radiation. To minimize bremsstrahlung in the radiation for calibration we also provide various foils as filters. For experimental purposes, a vacuum box capable of 10{sup -7} Torr, as well as HPGe and CdTe radiation detectors, are provided on an optical table. Most geometries and arrangements can be changed to meet experimental needs.

  7. X-ray selected galaxy clusters in the Pan-STARRS Medium Deep Survey

    NASA Astrophysics Data System (ADS)

    Ebeling, H.; Edge, A. C.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Price, P. A.; Tonry, J. L.

    2013-06-01

    We present the results of a pilot study for the extended Massive Cluster Survey (eMACS), a comprehensive search for distant, X-ray luminous galaxy clusters at z > 0.5. Our pilot study applies the eMACS concept to the 71 deg2 area extended by the 10 fields of the Pan-STARRS1 (PS1) Medium Deep Survey (MDS). Candidate clusters are identified by visual inspection of PS1 images in the g, r, i and z bands in a 5 × 5 arcmin2 region around X-ray sources detected in the ROSAT All-Sky Survey (RASS). To test and optimize the eMACS X-ray selection criteria, our pilot study uses the largest possible RASS data base, i.e. all RASS sources listed in the Bright and Faint Source Catalogues (BSC and FSC) that fall within the MDS footprint. We apply no additional constraints regarding X-ray flux, spectral hardness ratio or photon statistics and lower the redshift threshold to z > 0.3 to extend the probed luminosity range to poorer systems. Scrutiny of PS1/MDS images for 41 BSC and 200 FSC sources combined with dedicated spectroscopic follow-up observations results in a sample of 11 clusters with estimated or spectroscopic redshifts of z > 0.3. In order to assess and quantify the degree of point source contamination of the observed RASS fluxes, we examine archival Chandra data obtained in targeted and serendipitous observations of six of the 11 clusters found. As expected, the diffuse emission from all six systems is contaminated by point sources to some degree, and for half of them active galactic nucleus emission dominates. X-ray follow-up observations will thus be crucial in order to establish robust cluster luminosities for eMACS clusters. Although the small number of distant X-ray luminous clusters in the MDS does not allow us to make firm predictions for the over 20 000 deg2 of extragalactic sky covered by eMACS, the identification of two extremely promising eMACS cluster candidates at z ≳ 0.6 (both yet to be observed with Chandra) in such a small solid angle is encouraging

  8. Studying X-Ray Binaries with High Energy Frequency Quasi-Periodic Oscillations

    NASA Technical Reports Server (NTRS)

    Kaaret, P.; West, Donald K. (Technical Monitor)

    2002-01-01

    The goal of this investigation is to further our understanding of the dynamics of secreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fetus. The main focus of this work has been a multi-year program of simultaneous millisecond X-ray timing and spectral observations carried out with the Rossi X-Ray Timing Explorer (RXTE) to perform the X-ray timing and one of the satellites Asca, BeppoSAX, or Chandra to perform X-ray spectral measurements. With the advent of Chandra, we have extended our work to incLude extragalactic X-ray binaries. We conducted a comprehensive study of the X-ray and radio behavior of the Black Hole Candidate (BHC) X-ray transient XTE J1550-564 using RXTE, Chandra, and the Australian Telescope Compact Array (ATCA). We showed that strong radio emission is associated with major X-ray outbursts involving an X-ray state transition, while a compact radio jet is seen in the low/hard X-ray state found in the outburst decay. Interesting, the total energy required to produce the compact jet may be a substantial fraction of the total accretion energy of the system in that state. We also performed a detailed study of the spectral and timing properties of the decay. In joint RXTE/BeppoSAX observations of the neutron-star X-ray binary Cyg X-2, we discovered a correlation between the timing properties (the frequency of the horizontal branch oscillations) and the properties of a soft, thermal component of the X-ray spectrum. d e showed that more detX- ray from accreting neutron stars. We have completed analysis of RXTE observations of the X-ray transient SAX J1750.8-2900 made after detection of X-ray bursts from the source with the BeppoSAX Wide-Field Camera. We discovered millisecond oscillations in both the persistent emission and in the X-ray bursts.

  9. The high energy X-ray spectrum of the Crab Nebula observed from OSO 8

    NASA Technical Reports Server (NTRS)

    Dolan, J. F.; Crannell, L. J.; Dennis, B. R.; Orwig, L. E.; Maurer, G. S.; Frost, K. J.

    1977-01-01

    The X-ray spectrum of the Crab Nebula was measured with the scintillation spectrometer on board the OSO-8 satellite. The total emission of the X-ray source shows no long term variability. The spectrum itself can be described by a single power law out to energies of at least 500 keV.

  10. Relative calibration of energy thresholds on multi-bin spectral x-ray detectors

    NASA Astrophysics Data System (ADS)

    Sjölin, M.; Danielsson, M.

    2016-12-01

    Accurate and reliable energy calibration of spectral x-ray detectors used in medical imaging is essential for avoiding ring artifacts in the reconstructed images (computed tomography) and for performing accurate material basis decomposition. A simple and accurate method for relative calibration of the energy thresholds on a multi-bin spectral x-ray detector is presented. The method obtains the linear relations between all energy thresholds in a channel by scanning the thresholds with respect to each other during x-ray illumination. The method does not rely on a model of the detector's response function and does not require any identifiable features in the x-ray spectrum. Applying the same method, the offset between the thresholds can be determined also without external stimuli by utilizing the electronic noise as a source. The simplicity and accuracy of the method makes it suitable for implementation in clinical multi-bin spectral x-ray imaging systems.

  11. Phase-contrast microscopy at high x-ray energy with a laboratory setup.

    PubMed

    Endrizzi, Marco; Vittoria, Fabio A; Diemoz, Paul C; Lorenzo, Rodolfo; Speller, Robert D; Wagner, Ulrich H; Rau, Christoph; Robinson, Ian K; Olivo, Alessandro

    2014-06-01

    We report on the design and realization of an x-ray imaging system for quantitative phase-contrast microscopy at high x-ray energy with laboratory-scale instrumentation. Phase and amplitude were separated quantitatively at x-ray energies up to 80 keV with micrometric spatial resolution. The accuracy of the results was tested against numerical simulations, and the spatial resolution was experimentally quantified by measuring a Siemens star phase object. This simple setup should find broad application in those areas of x-ray imaging where high energy and spatial resolution are simultaneously required and in those difficult cases where the sample contains materials with similar x-ray absorption.

  12. X-ray synchrotron dual energy imaging for material specific study

    NASA Astrophysics Data System (ADS)

    Singh, B.; Agrawal, A. K.; Kashyap, Y. S.; Gadkari, S. C.

    2017-05-01

    X-ray imaging techniques, in general, are used to study the internal structures of an object non-destructively such as anatomy, imperfections, cracks and voids whereas insensitive to spatial distribution of different element or elemental compositions of the object. With the development of advance bright X-ray synchrotron sources and accurate energy tunability using high resolution crystal monochromator, detection of elemental distribution in an object became possible. Quantitative small concentrations with enhance contrast can be detected fast in X-ray synchrotron based dual energy imaging, in comparison to conventional X-ray lab based techniques. We report here the experimental setup, image acquisition and image processing for the dual energy X-ray imaging (DEI) technique to retrieve the spatial distribution of different elements in the object.

  13. Soft X-ray bremsstrahlung and fluorescent line production in the atmosphere by low energy electrons

    NASA Technical Reports Server (NTRS)

    Kraushaar, W. L.

    1974-01-01

    The effect of low energy quasi-trapped or precipitating electrons which impact on the counter windows of soft X-ray detectors are discussed. The errors caused by X-rays produced in the residual atmosphere above a rocket-borne detector because of the resemblance to X-rays of cosmic origin are examined. The design and development of counter windows which make it possible to identify the atmospherically produced X-rays are described. Curves are presented to show the following: (1) preliminary low energy electron data from Atmospheric Explorer C, (2) X-ray flux in electron-excited nitrogen and oxygen, (3) typical proportional counter response to low energy cosmic rays, and (4) proportional counter response to X-radiation produced by electrons incident upon a gas of oxygen to nitrogen number of 0.4.

  14. Single photon energy dispersive x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Higginbotham, Andrew; Patel, Shamim; Hawreliak, James A.; Ciricosta, Orlando; Collins, Gilbert W.; Coppari, Federica; Eggert, Jon H.; Suggit, Matthew J.; Tang, Henry; Wark, Justin S.

    2014-03-01

    With the pressure range accessible to laser driven compression experiments on solid material rising rapidly, new challenges in the diagnosis of samples in harsh laser environments are emerging. When driving to TPa pressures (conditions highly relevant to planetary interiors), traditional x-ray diffraction techniques are plagued by increased sources of background and noise, as well as a potential reduction in signal. In this paper we present a new diffraction diagnostic designed to record x-ray diffraction in low signal-to-noise environments. By utilising single photon counting techniques we demonstrate the ability to record diffraction patterns on nanosecond timescales, and subsequently separate, photon-by-photon, signal from background. In doing this, we mitigate many of the issues surrounding the use of high intensity lasers to drive samples to extremes of pressure, allowing for structural information to be obtained in a regime which is currently largely unexplored.

  15. Single photon energy dispersive x-ray diffraction

    SciTech Connect

    Higginbotham, Andrew; Patel, Shamim; Ciricosta, Orlando; Suggit, Matthew J.; Wark, Justin S.; Hawreliak, James A.; Collins, Gilbert W.; Coppari, Federica; Eggert, Jon H.; Tang, Henry

    2014-03-15

    With the pressure range accessible to laser driven compression experiments on solid material rising rapidly, new challenges in the diagnosis of samples in harsh laser environments are emerging. When driving to TPa pressures (conditions highly relevant to planetary interiors), traditional x-ray diffraction techniques are plagued by increased sources of background and noise, as well as a potential reduction in signal. In this paper we present a new diffraction diagnostic designed to record x-ray diffraction in low signal-to-noise environments. By utilising single photon counting techniques we demonstrate the ability to record diffraction patterns on nanosecond timescales, and subsequently separate, photon-by-photon, signal from background. In doing this, we mitigate many of the issues surrounding the use of high intensity lasers to drive samples to extremes of pressure, allowing for structural information to be obtained in a regime which is currently largely unexplored.

  16. Single photon energy dispersive x-ray diffraction.

    PubMed

    Higginbotham, Andrew; Patel, Shamim; Hawreliak, James A; Ciricosta, Orlando; Collins, Gilbert W; Coppari, Federica; Eggert, Jon H; Suggit, Matthew J; Tang, Henry; Wark, Justin S

    2014-03-01

    With the pressure range accessible to laser driven compression experiments on solid material rising rapidly, new challenges in the diagnosis of samples in harsh laser environments are emerging. When driving to TPa pressures (conditions highly relevant to planetary interiors), traditional x-ray diffraction techniques are plagued by increased sources of background and noise, as well as a potential reduction in signal. In this paper we present a new diffraction diagnostic designed to record x-ray diffraction in low signal-to-noise environments. By utilising single photon counting techniques we demonstrate the ability to record diffraction patterns on nanosecond timescales, and subsequently separate, photon-by-photon, signal from background. In doing this, we mitigate many of the issues surrounding the use of high intensity lasers to drive samples to extremes of pressure, allowing for structural information to be obtained in a regime which is currently largely unexplored.

  17. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  18. Compact pnCCD-based X-ray camera with high spatial and energy resolution: a color X-ray camera.

    PubMed

    Scharf, O; Ihle, S; Ordavo, I; Arkadiev, V; Bjeoumikhov, A; Bjeoumikhova, S; Buzanich, G; Gubzhokov, R; Günther, A; Hartmann, R; Kühbacher, M; Lang, M; Langhoff, N; Liebel, A; Radtke, M; Reinholz, U; Riesemeier, H; Soltau, H; Strüder, L; Thünemann, A F; Wedell, R

    2011-04-01

    For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 μm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69,696 spectra with an energy resolution of 152 eV for manganese K(α) with a spatial resolution of 50 μm over an imaging area of 12.7 × 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 μm beryllium window, and the sensitive thickness of 450 μm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.

  19. Shielded radiography with a laser-driven MeV-energy X-ray source

    NASA Astrophysics Data System (ADS)

    Chen, Shouyuan; Golovin, Grigory; Miller, Cameron; Haden, Daniel; Banerjee, Sudeep; Zhang, Ping; Liu, Cheng; Zhang, Jun; Zhao, Baozhen; Clarke, Shaun; Pozzi, Sara; Umstadter, Donald

    2016-01-01

    We report the results of experimental and numerical-simulation studies of shielded radiography using narrowband MeV-energy X-rays from a compact all-laser-driven inverse-Compton-scattering X-ray light source. This recently developed X-ray light source is based on a laser-wakefield accelerator with ultra-high-field gradient (GeV/cm). We demonstrate experimentally high-quality radiographic imaging (image contrast of 0.4 and signal-to-noise ratio of 2:1) of a target composed of 8-mm thick depleted uranium shielded by 80-mm thick steel, using a 6-MeV X-ray beam with a spread of 45% (FWHM) and 107 photons in a single shot. The corresponding dose of the X-ray pulse measured in front of the target is ∼100 nGy/pulse. Simulations performed using the Monte-Carlo code MCNPX accurately reproduce the experimental results. These simulations also demonstrate that the narrow bandwidth of the Compton X-ray source operating at 6 and 9 MeV leads to a reduction of deposited dose as compared to broadband bremsstrahlung sources with the same end-point energy. The X-ray beam's inherently low-divergence angle (∼mrad) is advantageous and effective for interrogation at standoff distance. These results demonstrate significant benefits of all-laser driven Compton X-rays for shielded radiography.

  20. High-energy x-ray backlighter spectrum measurements using calibrated image plates

    SciTech Connect

    Maddox, B.R.; Park, H.S.; Remington, B.A.; Izumi, N.; Chen, S.; Chen, C.; Kimminau, G.; Ali, Z.; Haugh, M.J.; Ma, Q.

    2012-10-10

    The x-ray spectrum between 18 and 88 keV generated by a petawatt laser driven x-ray backlighter target was measured using a 12-channel differential filter pair spectrometer. The spectrometer consists of a series of filter pairs on a Ta mask coupled with an x-ray sensitive image plate. A calibration of Fuji{trademark} MS and SR image plates was conducted using a tungsten anode x-ray source and the resulting calibration applied to the design of the Ross pair spectrometer. Additionally, the fade rate and resolution of the image plate system were measured for quantitative radiographic applications. The conversion efficiency of laser energy into silver K{alpha} x rays from a petawatt laser target was measured using the differential filter pair spectrometer and compared to measurements using a single photon counting charge coupled device.

  1. Theoretical consideration of the energy resolution in planar HPGe detectors for low energy X-rays

    SciTech Connect

    Samedov, Victor V.

    2015-07-01

    In this work, theoretical consideration of the processes in planar High Purity Ge (HPGe) detectors for low energy X-rays using the random stochastic processes formalism was carried out. Using the random stochastic processes formalism, the generating function of the processes of X-rays registration in a planar HPGe detector was derived. The power serial expansions of the detector amplitude and the variance in terms of the inverse bias voltage were derived. The coefficients of these expansions allow determining the Fano factor, electron mobility lifetime product, nonuniformity of the trap density, and other characteristics of the semiconductor material. (authors)

  2. Soft X-ray Charged Piezoelectret for Kinetic Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Lu, J.; Cho, HJ; Suzuki, Y.

    2016-11-01

    Piezoelectret polymer attracts much attention for its high piezoelectric coefficient. Multilayered piezoelectret structures are often charged with corona discharge, but it is difficult to get high surface charge density. To address this issue, a multilayered piezoelectret structure with embedded electrode is proposed, which can be efficiently poled with soft X-ray charging. With the aid of embedded electrodes, the bias voltage is directly applied to each unit cell, rather than divided and distributed to multiple layers. With an early PTFE-based prototype, output power of 0.5 μJ has been obtained for 0.3 mm displacement in 0.2 s.

  3. Scintillator Evaluation for High-Energy X-Ray Diagnostics

    SciTech Connect

    S. S. Lutz; S. A. Baker

    2001-09-01

    This report presents results derived from a digital radiography study performed using x-rays from a 2.3 MeV, rod-pinch diode. Detailed is a parameter study of cerium-doped lutetium ortho-silicate (LSO) scintillator thickness, as it relates to system resolution and detection quantum efficiency (DQE). Additionally, the detection statistics of LSO were compared with that of CsI(Tl). As a result of this study we found the LSO scintillator with a thickness of 3 mm to yield the highest system DQE over the range of spatial frequencies from 0.75 to 2.5 mm{sup -1}.

  4. High-energy resolution X-ray, gamma and electron spectroscopy with cryogenic detectors.

    PubMed

    Loidl, M; Leblanc, E; Bouchard, J; Branger, T; Coron, N; Leblanc, J; de Marcillac, P; Rotzinger, H; Daniyarov, T; Linck, M; Fleischmann, A; Enss, C

    2004-01-01

    Cryogenic detectors offer remarkably better energy resolutions than those achievable with conventional semiconductor or scintillation detectors. With the additional asset of a detection efficiency close to unity for low-energy X-ray photons and electrons, these detectors have the potential to perform X-ray, gamma and electron spectroscopy of a hitherto unknown quality, in particular at low energies. Two types of cryogenic detectors are described and the results of prototype detectors are presented.

  5. High Energy Astronomy Observatory (HEAO)-2 in the X-Ray Calibration Facility

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being evaluated by engineers in the clean room of the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

  6. High Energy Astronomy Observatory (HEAO)-2 in the X-Ray Calibration Facility

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being evaluated by engineers in the clean room of the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

  7. High energy X-ray phase and dark-field imaging using a random absorption mask

    PubMed Central

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-01-01

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science. PMID:27466217

  8. High-energy x-ray imaging diagnostics of nanosecond pulse accelerators

    NASA Astrophysics Data System (ADS)

    Smith, Graham W.; Hohlfelder, Robert J.; Tribe, Alun J.; Beutler, David E.; Gallegos, Roque R.; Seymour, Calvin L. G.; Thompson, Jon A.

    2007-01-01

    X-ray imaging has been undertaken on Sandia National Laboratories' radiation effects x-ray simulators. These simulators typically yield a single very short (<20ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad (Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.5 to 1.8MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and an evaluation of the capability of the spectrometer are presented.

  9. Absolute x-ray energy calibration and monitoring using a diffraction-based method

    SciTech Connect

    Hong, Xinguo Weidner, Donald J.; Duffy, Thomas S.; Ehm, Lars

    2016-07-27

    In this paper, we report some recent developments of the diffraction-based absolute X-ray energy calibration method. In this calibration method, high spatial resolution of the measured detector offset is essential. To this end, a remotely controlled long-translation motorized stage was employed instead of the less convenient gauge blocks. It is found that the precision of absolute X-ray energy calibration (ΔE/E) is readily achieved down to the level of 10{sup −4} for high-energy monochromatic X-rays (e.g. 80 keV). Examples of applications to pair distribution function (PDF) measurements and energy monitoring for high-energy X-rays are presented.

  10. Resonant Scattering of X-ray Emission Lines in the Hot Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Churazov, Eugene; Zhuravleva, Irina; Sazonov, Sergey; Sunyaev, Rashid

    2010-12-01

    While very often a hot intergalactic medium (IGM) is optically thin to continuum radiation, the optical depth in resonant lines can be of order unity or larger. Resonant scattering in the brightest X-ray emission lines can cause distortions in the surface brightness distribution, spurious variations in the abundance of heavy elements, changes in line spectral shapes and even polarization of line emission. The magnitude of these effects not only depends on the density, temperature and ionization state of the gas, but is also sensitive to the characteristics of the gas velocity field. This opens a possibility to use resonant scattering as a convenient and powerful tool to study IGM properties. We discuss the application of these effects to galaxy clusters.

  11. Soft X-Ray Transmission Spectroscopy of a Warm/Hot Intergalactic Medium with XEUS

    NASA Astrophysics Data System (ADS)

    Kawahara, Hajime; Yoshikawa, Kohji; Sasaki, Shin; Suto, Yasushi; Kawai, Nobuyuki; Mitsuda, Kazuhisa; Ohashi, Takaya; Yamasaki, Noriko Y.

    2006-08-01

    We discuss the detectability of a Warm/Hot Intergalactic Medium (WHIM) via absorption lines toward bright point sources with a future X-ray satellite mission, XEUS. While we consider bright QSOs as specific examples, the methodology can be applied to bright gamma-ray burst afterglows. We created mock absorption spectra for bright QSOs (more than 20 QSOs over all sky) using the light-cone output of a cosmological hydrodynamic simulation. We assumed that the WHIM is under collisional and photo-ionization equilibrium. If WHIM has a constant metallicity of Z = 0.1Zodot, approximately 2 O VII absorption line systems with > 3σ will be detected on average along a random line-of-sight toward bright QSOs up to z = 0.3 for a 30ks exposure.

  12. X-ray fluorescence and energy dispersive x-ray diffraction for the quantification of elemental concentrations in breast tissue.

    PubMed

    Geraki, K; Farquharson, M J; Bradley, D A

    2004-01-07

    This paper presents improvements on a previously reported method for the measurement of elements in breast tissue specimens (Geraki et al 2002 Phys. Med. Biol. 47 2327-39). A synchrotron-based system was used for the detection of the x-ray fluorescence (XRF) emitted from iron, copper, zinc and potassium in breast tissue specimens, healthy and cancerous. Calibration models resulting from the irradiation of standard aqueous solutions were used for the quantification of the elements. The present developments concentrate on increasing the convergence between the tissue samples and the calibration models, therefore improving accuracy. For this purpose the composition of the samples in terms of adipose and fibrous tissue was evaluated, using an energy dispersive x-ray diffraction (EDXRD) system. The relationships between the attenuation and scatter properties of the two tissue components and water were determined through Monte Carlo simulations. The results from the simulations and the EDXRD measurements allowed the XRF data from each specimen to be corrected according to its composition. The statistical analysis of the elemental concentrations of the different groups of specimens reveals that all four elements are found in elevated levels in the tumour specimens. The increase is less pronounced for iron and copper and most for potassium and zinc. Other observed features include the substantial degree of inhomogeneity of elemental distributions within the volume of the specimens, varying between 4% and 36% of the mean, depending on the element and the type of the sample. The accuracy of the technique, based on the measurement of a standard reference material, proved to be between 3% and 22% depending on the element, which presents only a marginal improvement (1%-3%) compared to the accuracy of the previously reported results. The measurement precision was between 1% and 9% while the calculated uncertainties on the final elemental concentrations ranged between 10% and 16%.

  13. Therapy Imaging: Limitations Of Imaging With High Energy X-Ray Beams

    NASA Astrophysics Data System (ADS)

    Munro, P.; Rawlinson, J. A.; Fenster, A.

    1987-01-01

    One of the major problems in radiation therapy is ensuring that the correct region of the patient receives the prescribed x-ray treatment and that the surrounding tissues are spared. One way to identify patient positioning errors is to make an image using the radiotherapy treatment beam. We have examined two of the factors that can influence the quality of images made with high energy x-ray beams: (i) the size of the x-ray source, and; (ii) the signal-to-noise characteristics of the detectors used to form images with high energy x-ray beams. We have developed a novel method of measuring the source distributions for 60Co machines and linear accelerators and from the measurements have been able to obtain the modulation transfer functions of their x-ray sources. We have also measured the modulation transfer functions (MTFs) and the noise power spectra (NPS) of the x-ray detectors. Based on these measurements, we conclude that images made with high energy x-ray beams are limited by film granularity and that improved images can be obtained by alternative detector systems.

  14. Projection x-ray imaging with photon energy weighting: experimental evaluation with a prototype detector.

    PubMed

    Shikhaliev, Polad M

    2009-08-21

    The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very high count rates, good energy resolution and a large number of small pixels were required. These problems have been addressed with the advent of new detector materials, fast readout electronics and powerful computers. In this work, we report on the experimental evaluation of projection x-ray imaging with a photon counting cadmium-zinc-telluride (CZT) detector with energy resolving capabilities. The detector included two rows of pixels with 128 pixels per row with 0.9 x 0.9 mm(2) pixel size, and a 2 Mcount pixel(-1) s(-1) count rate. The x-ray tube operated at 120 kVp tube voltage with 2 mm Al-equivalent inherent filtration. The x-ray spectrum was split into five regions, and five independent x-ray images were acquired at a time. These five quasi-monochromatic x-ray images were used for x-ray energy weighting and material decomposition. A tissue-equivalent phantom was used including contrast elements simulating adipose, calcifications, iodine and air. X-ray energy weighting improved the SNR of calcifications and iodine by a factor of 1.32 and 1.36, respectively, as compared to charge integrating. Material decomposition was performed by dual energy subtraction. The low- and high-energy images were generated in the energy ranges of 25-60 keV and 60-120 keV, respectively, by combining five monochromatic image data into two. X-ray energy weighting was applied to low- and high-energy images prior to subtraction, and this improved the SNR of calcifications and iodine in dual energy subtracted images by a factor of 1.34 and 1.25, respectively, as compared to charge integrating. The detector energy resolution, spatial resolution, linearity, count rate, noise and

  15. Projection x-ray imaging with photon energy weighting: experimental evaluation with a prototype detector

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2009-08-01

    The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very high count rates, good energy resolution and a large number of small pixels were required. These problems have been addressed with the advent of new detector materials, fast readout electronics and powerful computers. In this work, we report on the experimental evaluation of projection x-ray imaging with a photon counting cadmium-zinc-telluride (CZT) detector with energy resolving capabilities. The detector included two rows of pixels with 128 pixels per row with 0.9 × 0.9 mm2 pixel size, and a 2 Mcount pixel-1 s-1 count rate. The x-ray tube operated at 120 kVp tube voltage with 2 mm Al-equivalent inherent filtration. The x-ray spectrum was split into five regions, and five independent x-ray images were acquired at a time. These five quasi-monochromatic x-ray images were used for x-ray energy weighting and material decomposition. A tissue-equivalent phantom was used including contrast elements simulating adipose, calcifications, iodine and air. X-ray energy weighting improved the SNR of calcifications and iodine by a factor of 1.32 and 1.36, respectively, as compared to charge integrating. Material decomposition was performed by dual energy subtraction. The low- and high-energy images were generated in the energy ranges of 25-60 keV and 60-120 keV, respectively, by combining five monochromatic image data into two. X-ray energy weighting was applied to low- and high-energy images prior to subtraction, and this improved the SNR of calcifications and iodine in dual energy subtracted images by a factor of 1.34 and 1.25, respectively, as compared to charge integrating. The detector energy resolution, spatial resolution, linearity, count rate, noise and image

  16. A SUZAKU SEARCH FOR NONTHERMAL EMISSION AT HARD X-RAY ENERGIES IN THE COMA CLUSTER

    SciTech Connect

    Wik, Daniel R.; Sarazin, Craig L.; Finoguenov, Alexis; Matsushita, Kyoko; Nakazawa, Kazuhiro; Clarke, Tracy E.

    2009-05-10

    The brightest cluster radio halo known resides in the Coma cluster of galaxies. The relativistic electrons producing this diffuse synchrotron emission should also produce inverse Compton emission that becomes competitive with thermal emission from the intracluster medium (ICM) at hard X-ray energies. Thus far, claimed detections of this emission in Coma are controversial. We present a Suzaku HXD-PIN observation of the Coma cluster in order to nail down its nonthermal hard X-ray content. The contribution of thermal emission to the HXD-PIN spectrum is constrained by simultaneously fitting thermal and nonthermal models to it and a spatially equivalent spectrum derived from an XMM-Newton mosaic of the Coma field. We fail to find statistically significant evidence for nonthermal emission in the spectra which are better described by only a single- or multitemperature model for the ICM. Including systematic uncertainties, we derive a 90% upper limit on the flux of nonthermal emission of 6.0 x 10{sup -12} erg s{sup -1} cm{sup -2} (20-80 keV, for {gamma} = 2.0), which implies a lower limit on the cluster-averaged magnetic field of B>0.15 {mu}G. Our flux upper limit is 2.5 times lower than the detected nonthermal flux from RXTE and BeppoSAX. However, if the nonthermal hard X-ray emission in Coma is more spatially extended than the observed radio halo, the Suzaku HXD-PIN may miss some fraction of the emission. A detailed investigation indicates that {approx}50%-67% of the emission might go undetected, which could make our limit consistent with that of Rephaeli and Gruber and Fusco-Femiano et al. The thermal interpretation of the hard Coma spectrum is consistent with recent analyses of INTEGRAL and Swift data.

  17. Two Distinct-absorption X-Ray Components from Type IIn Supernovae: Evidence for Asphericity in the Circumstellar Medium

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Maeda, Keiichi; Bamba, Aya; Terada, Yukikatsu; Fukazawa, Yasushi; Kawabata, Koji; Ohno, Masanori; Sugawara, Yasuharu; Tsuboi, Yohko; Immler, Stefan

    2016-12-01

    We present multi-epoch X-ray spectral observations of three Type IIn supernovae (SNe), SN 2005kd, SN 2006jd, and SN 2010jl, acquired with Chandra, XMM-Newton, Suzaku, and Swift. Previous extensive X-ray studies of SN 2010jl have revealed that X-ray spectra are dominated by thermal emission, which likely arises from a hot plasma heated by a forward shock propagating into a massive circumstellar medium (CSM). Interestingly, an additional soft X-ray component was required to reproduce the spectra at a period of ˜1-2 years after the SN explosion. Although this component is likely associated with the SN, its origin remained an open question. We find a similar, additional soft X-ray component from the other two SNe IIn as well. Given this finding, we present a new interpretation for the origin of this component; it is thermal emission from a forward shock essentially identical to the hard X-ray component, but directly reaches us from a void of the dense CSM. Namely, the hard and soft components are responsible for the heavily and moderately absorbed components, respectively. The co-existence of the two components with distinct absorptions as well as the delayed emergence of the moderately absorbed X-ray component could be evidence for asphericity of the CSM. We show that the X-ray spectral evolution can be qualitatively explained by considering a torus-like geometry for the dense CSM. Based on our X-ray spectral analyses, we estimate the radius of the torus-like CSM to be on the order of ˜5 × 1016 cm.

  18. X-Ray Photoelectron Spectroscopy and the Role of Relaxation Energy in Understanding Chemical Shifts

    ERIC Educational Resources Information Center

    Ellison, Frank O.; White, Michael G.

    1976-01-01

    Discusses the measurement of electrons ejected from a system which is being irradiated with X-rays or ultraviolet photons, and a theoretical model for calculating core-electron ionization energies. (MLH)

  19. Event-Driven X-Ray CCD Detectors for High Energy Astrophysics

    NASA Technical Reports Server (NTRS)

    Ricker, George R.

    2004-01-01

    A viewgraph presentation describing the Event-Driven X- Ray CCD (EDCCD) detector system for high energy astrophysics is presented. The topics include: 1) EDCCD: Description and Advantages; 2) Summary of Grant Activity Carried Out; and 3) EDCCD Test System.

  20. X-Ray Photoelectron Spectroscopy and the Role of Relaxation Energy in Understanding Chemical Shifts

    ERIC Educational Resources Information Center

    Ellison, Frank O.; White, Michael G.

    1976-01-01

    Discusses the measurement of electrons ejected from a system which is being irradiated with X-rays or ultraviolet photons, and a theoretical model for calculating core-electron ionization energies. (MLH)

  1. First Look at Milky Way Monster in High-Energy X-ray Light

    NASA Image and Video Library

    2012-10-23

    These images, taken by NASA black-hole hunter, NuSTAR, are the first, focused high-energy X-ray views of the area surrounding the supermassive black hole, called Sagittarius A*, at the center of our galaxy.

  2. Empirical studies of solar flares: Comparison of X-ray and H alpha filtergrams and analysis of the energy balance of the X-ray plasma

    NASA Technical Reports Server (NTRS)

    Moore, R. L.

    1979-01-01

    The physics of solar flares was investigated through a combined analysis of X-ray filtergrams of the high temperature coronal component of flares and H alpha filtergrams of the low temperature chromospheric component. The data were used to study the magnetic field configuration and its changes in solar flares, and to examine the chromospheric location and structure of X-ray bright points (XPB) and XPB flares. Each topic and the germane data are discussed. The energy balance of the thermal X-ray plasma in flares, while not studied, is addressed.

  3. Multi-energy image sequence fusion based on variable energy X-ray imaging.

    PubMed

    Liu, Bin; Han, Yan; Pan, Jinxiao; Chen, Ping

    2014-01-01

    For complicated structural components characterized by wide X-ray attenuation ranges, the conventional fixed-energy imaging mode cannot obtain all structural information using a single tube voltage. This limitation results in information shortage, because the effective thickness of components along the orientation of the X-ray penetration exceeds the limit of the dynamic range of the X-ray imaging system. To solve this problem, multi-energy image sequence fusion technology has been advanced. In this new method, the tube voltage is adjusted several times by matching the voltage and the effective thickness to obtain all the effective local information on an object. Then, the subset sequences in the multi-energy image sequence are extracted based on the recursive template, and that are fused to reconstruct the full projection information based on linear weighting. An accompanying experiment demonstrates that the new technology can extend the dynamic range of X-ray imaging and provide a complete representation of the internal structure of complicated structural components.

  4. Investigation of TLD-700 energy response to low energy x-ray encountered in diagnostic radiology

    NASA Astrophysics Data System (ADS)

    Herrati, Ammar; Bourouina, Mourad; Khalal-Kouache, Karima

    2016-01-01

    The aim of thiswork is to study the energy dependence of thermoluminescent dosimeter (TLD-700) for low energy X-ray beams encountered in conventional diagnostic radiology. In the first step, we studied some characteristics (reproducibility and linearity) of TLD-700 chips using a 137Cs source, and selected TLD chips with reproducibility better than 2.5%. Then we determined TLD-700 energy response for diagnostic radiology X-ray qualities, and investigated its influence on air kerma estimate. A maximum deviation of 60% can be obtained if TLDs are calibrated for 137Cs radiation source and used in diagnostic radiology fields. However, this deviation became less than 20% if TLDs chips are calibrated for the reference x-ray radiation quality RQR5 (recommended by the IEC 61267 standard). Consequently, we recommend calibrating this kind of TLDdetector with RQR5 diagnostic radiology X-ray quality. This method permits to obtain a good accuracy when assessing the entrance dose in diagnostic radiology procedures.

  5. The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: the high energy x-ray source and some applications.

    PubMed

    Hubert, S; Dubois, J L; Gontier, D; Lidove, G; Reverdin, C; Soullié, G; Stemmler, P; Villette, B

    2010-05-01

    The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented.

  6. Energy-Discriminating Gadolinium K-Edge X-ray Computed Tomography System

    NASA Astrophysics Data System (ADS)

    Matsukiyo, Hiroshi; Watanabe, Manabu; Sato, Eiichi; Osawa, Akihiro; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; AIzawa, Katsuo; Hitomi, Keitaro; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ogawa, Akira; Takahashi, Kiyomi; Sato, Shigehiro; Onagawa, Jun

    2010-02-01

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type of detector using cadmium telluride (CdTe). CT is performed by repeated translations and rotations of an object. Penetrating X-ray photons from the object are detected by a CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both photon energy and energy width are selected out using a multichannel analyzer, and the number of photons is counted by a countercard. To perform energy discrimination, a low-dose-rate X-ray generator for photon counting was developed. Its maximum tube voltage and minimum tube current were 110 kV and 1 µA, respectively. In energy-discriminating CT, the tube voltage and tube current were 100 kV and 20 µA, respectively, and the X-ray intensity was 2.98 µGy/s at a distance of 1.0 m from the source and a tube voltage of 100 kV. The demonstration of enhanced gadolinium K-edge X-ray CT was carried out by selecting photons with energies just beyond the gadolinium K-edge energy of 50.3 keV.

  7. Energy-Discriminating Gadolinium K-Edge X-ray Computed Tomography System

    NASA Astrophysics Data System (ADS)

    Hiroshi Matsukiyo,; Manabu Watanabe,; Eiichi Sato,; Akihiro Osawa,; Toshiyuki Enomoto,; Jiro Nagao,; Purkhet Abderyim,; Katsuo AIzawa,; Keitaro Hitomi,; Etsuro Tanaka,; Hidezo Mori,; Toshiaki Kawai,; Akira Ogawa,; Kiyomi Takahashi,; Shigehiro Sato,; Jun Onagawa,

    2010-02-01

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type of detector using cadmium telluride (CdTe). CT is performed by repeated translations and rotations of an object. Penetrating X-ray photons from the object are detected by a CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both photon energy and energy width are selected out using a multichannel analyzer, and the number of photons is counted by a countercard. To perform energy discrimination, a low-dose-rate X-ray generator for photon counting was developed. Its maximum tube voltage and minimum tube current were 110 kV and 1 μA, respectively. In energy-discriminating CT, the tube voltage and tube current were 100 kV and 20 μA, respectively, and the X-ray intensity was 2.98 μGy/s at a distance of 1.0 m from the source and a tube voltage of 100 kV. The demonstration of enhanced gadolinium K-edge X-ray CT was carried out by selecting photons with energies just beyond the gadolinium K-edge energy of 50.3 keV.

  8. Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions

    SciTech Connect

    Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin

    2013-10-15

    Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 10{sup 14} to 1.8 × 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

  9. Energy-dependent Orbital Modulation of X-rays and Constraints on Emission of the Jet in Cyg X-3

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Maitra, Chandreyee; Frankowski, Adam; Skinner, Gerald K.; Misra, Ranjeev

    2012-01-01

    We study orbital modulation of X-rays from Cyg X-3, using data from Swift, INTEGRAL and RXTE. Using the wealth of the presently available data and an improved averaging method, we obtain energy-dependent folded and averaged light curves with unprecedented accuracy. We find that above 5 keV, the modulation depth decreases with the increasing energy, which is consistent with the modulation being caused by both bound-free absorption and Compton scattering in the stellar wind of the donor, with minima corresponding to the highest optical depth, which occurs around the superior conjunction. We find a decrease of the depth below 3 keV, which appears to be due to re-emission of the absorbed continuum by the wind in soft X-ray lines. Based on the shape of the folded light curves, any X-ray contribution from the jet in Cyg X-3, which emits ?-rays detected at energies > 0.1 GeV in soft spectral states, is found to be minor up to 100 keV. This implies the presence of a rather sharp low-energy break in the jet MeV-range spectrum.We also calculate phase-resolved RXTE X-ray spectra, and show the difference between the spectra corresponding to phases around the superior and inferior conjunctions can indeed be accounted for by a combined effect of bound-free absorption in an ionized medium and Compton scattering.

  10. Bone mineral measurement using dual energy x ray densitometry

    NASA Technical Reports Server (NTRS)

    Smith, Steven W.

    1989-01-01

    Bone mineral measurements before and after space missions have shown that weightlessness greatly accelerates bone demineralization. Bone mineral losses as high as 1 to 3 percent per month were reported. Highly precise instrumentation is required to monitor this loss and thereby test the efficacy of treatment. During the last year, a significant improvement was made in Dual-Photon Absorptiometry by replacing the radioactive source with an x ray tube. Advantages of this system include: better precision, lower patient dose, better spacial resolution, and shorter scan times. The high precision and low radiation dose of this technique will allow detection of bone mineral changes of less than 1 percent with measurements conducted directly at the sites of interest. This will allow the required bone mineral studies to be completed in a shorter time with greater confidence.

  11. Energy response calibration of photon-counting detectors using X-ray fluorescence: a feasibility study

    PubMed Central

    Cho, H-M; Ding, H; Ziemer, BP; Molloi, S

    2014-01-01

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using X-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for X-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The angular dependence of X-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded X-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of X-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of X-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic X-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the X-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory. PMID:25369288

  12. Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study.

    PubMed

    Cho, H-M; Ding, H; Ziemer, B P; Molloi, S

    2014-12-07

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm(2) in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

  13. Energy Dependence of Synchrotron X-Ray Rims in Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Tran, Aaron; Williams, Brian J.; Petre, Robert; Ressler, Sean M.; Reynolds, Stephen P.

    2015-01-01

    Several young supernova remnants exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims require strong magnetic field amplification beyond simple shock compression if rim widths are only limited by electron energy losses. But, magnetic field damping behind the shock could produce similarly thin rims with less extreme field amplification. Variation of rim width with energy may thus discriminate between competing influences on rim widths. We measured rim widths around Tycho's supernova remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy and are well described by either loss-limited or damped scenarios, so X-ray rim width-energy dependence does not uniquely specify a model. But, radio counterparts to thin rims are not loss-limited and better reflect magnetic field structure. Joint radio and X-ray modeling favors magnetic damping in Tycho's SNR with damping lengths approximately 1-5% of remnant radius and magnetic field strengths approximately 50-400 micron G assuming Bohm diffusion. X-ray rim widths are approximately 1% of remnant radius, somewhat smaller than inferred damping lengths. Electron energy losses are important in all models of X-ray rims, suggesting that the distinction between loss-limited and damped models is blurred in soft X-rays. All loss-limited and damping models require magnetic fields approximately greater than 20 micron G, arming the necessity of magnetic field amplification beyond simple compression.

  14. Energy dispersive X-Ray fluorescence determination of thorium in phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Mirashi, N. N.; Dhara, Sangita; Kumar, S. Sanjay; Chaudhury, Satyajeet; Misra, N. L.; Aggarwal, S. K.

    2010-07-01

    Energy dispersive X-ray fluorescence studies on determination of thorium (in the range of 7 to 137 mg/mL) in phosphoric acid solutions obtained by dissolution of thoria in autoclave were made. Fixed amounts of Y internal standard solutions, after dilution with equal amount of phosphoric acid, were added to the calibration as well as sample solutions. Solution aliquots of approximately 2-5 µL were deposited on thick absorbent sheets to absorb the solutions and the sheets were presented for energy dispersive X-ray fluorescence measurements. A calibration plot was made between intensity ratios (Th Lα/Y Kα) against respective amounts of thorium in the calibration solutions. Thorium amounts in phosphoric acid samples were determined using their energy dispersive X-ray fluorescence spectra and the above calibration plot. The energy dispersive X-ray fluorescence results, thus obtained, were compared with the corresponding gamma ray spectrometry results and were found to be within average deviation of 2.6% from the respective gamma ray spectrometry values. The average precision obtained in energy dispersive X-ray fluorescence determinations was found to be 4% (1 σ). The energy dispersive X-ray fluorescence method has an advantage over gamma ray spectrometry for thorium determination as the amount of sample required and measurement time is far less compared to that required in gamma ray spectrometry.

  15. ENERGY DEPENDENCE OF SYNCHROTRON X-RAY RIMS IN TYCHO’S SUPERNOVA REMNANT

    SciTech Connect

    Tran, Aaron; Williams, Brian J.; Petre, Robert; Reynolds, Stephen P.

    2015-10-20

    Several young supernova remnants (SNRs) exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims require strong magnetic field amplification beyond simple shock compression if rim widths are only limited by electron energy losses. But, magnetic field damping behind the shock could produce similarly thin rims with less extreme field amplification. Variation of rim width with energy may thus discriminate between competing influences on rim widths. We measured rim widths around Tycho's SNR in five energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy and are well described by either loss-limited or damped scenarios, so X-ray rim width-energy dependence does not uniquely specify a model. But, radio counterparts to thin rims are not loss-limited and better reflect magnetic field structure. Joint radio and X-ray modeling favors magnetic damping in Tycho's SNR with damping lengths ∼1%–5% of remnant radius and magnetic field strengths ∼50–400 μG assuming Bohm diffusion. X-ray rim widths are ∼1% of remnant radius, somewhat smaller than inferred damping lengths. Electron energy losses are important in all models of X-ray rims, suggesting that the distinction between loss-limited and damped models is blurred in soft X-rays. All loss-limited and damping models require magnetic fields ≳20 μG, affirming the necessity of magnetic field amplification beyond simple compression.

  16. Fat to muscle ratio measurements with dual energy x-ray absorbtiometry

    SciTech Connect

    Chen, A.; Luo, J.; Wang, A.; Broadbent, C.; Zhong, J.; Dilmanian, F. A.; Zafonte, F.; Zhong, Z.

    2015-03-14

    Accurate measurement of the fat-to-muscle ratio in animal model is important for obesity research. In addition, an efficient way to measure the fat to muscle ratio in animal model using dual-energy absorptiometry is presented in this paper. A radioactive source exciting x-ray fluorescence from a target material is used to provide the two x-ray energies needed. The x-rays, after transmitting through the sample, are measured with an energy-sensitive Ge detector. Phantoms and specimens were measured. The results showed that the method was sensitive to the fat to muscle ratios with good linearity. A standard deviation of a few percent in the fat to muscle ratio could be observed with the x-ray dose of 0.001 mGy.

  17. Fat to muscle ratio measurements with dual energy x-ray absorbtiometry

    DOE PAGES

    Chen, A.; Luo, J.; Wang, A.; ...

    2015-03-14

    Accurate measurement of the fat-to-muscle ratio in animal model is important for obesity research. In addition, an efficient way to measure the fat to muscle ratio in animal model using dual-energy absorptiometry is presented in this paper. A radioactive source exciting x-ray fluorescence from a target material is used to provide the two x-ray energies needed. The x-rays, after transmitting through the sample, are measured with an energy-sensitive Ge detector. Phantoms and specimens were measured. The results showed that the method was sensitive to the fat to muscle ratios with good linearity. A standard deviation of a few percent inmore » the fat to muscle ratio could be observed with the x-ray dose of 0.001 mGy.« less

  18. Fat to muscle ratio measurements with dual energy x-ray absorbtiometry

    NASA Astrophysics Data System (ADS)

    Chen, A.; Luo, J.; Wang, A.; Broadbent, C.; Zhong, J.; Dilmanian, F. A.; Zafonte, F.; Zhong, Z.

    2015-07-01

    Accurate measurement of the fat-to-muscle ratio in animal model is important for obesity research. An efficient way to measure the fat to muscle ratio in animal model using dual-energy absorptiometry is presented in this paper. A radioactive source exciting x-ray fluorescence from a target material is used to provide the two x-ray energies needed. The x-rays, after transmitting through the sample, are measured with an energy-sensitive Ge detector. Phantoms and specimens were measured. The results showed that the method was sensitive to the fat to muscle ratios with good linearity. A standard deviation of a few percent in the fat to muscle ratio could be observed with the x-ray dose of 0.001 mGy.

  19. Inferring the Energy Distribution of Accelerated Electrons in Solar Flares from X-ray Observations

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Linhui; Su, Yang

    2008-01-01

    Knowledge of the energy distribution of electrons accelerated in solar flares is important for constraining possible acceleration mechanisms and for understanding the relationships between flare X-ray sources, radio sources, and particles observed in space. Solar flare hard X-rays are primarily emitted from dense, thick-target regions in the lower atmosphere, but the electrons are understood to be accelerated higher in the corona. Various processes can distort the X-ray spectrum or the energy distribution of electrons before they reach the thick-target region. After briefly reviewing the processes that affect the X-ray spectrum and the electron distribution, I will describe recent results from a study of flare spectra from RHESSI to determine the importance of these processes in inferring the energy distribution of accelerated electrons.

  20. Inferring the Energy Distribution of Accelerated Electrons in Solar Flares from X-ray Observations

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Linhui; Su, Yang

    2008-01-01

    Knowledge of the energy distribution of electrons accelerated in solar flares is important for constraining possible acceleration mechanisms and for understanding the relationships between flare X-ray sources, radio sources, and particles observed in space. Solar flare hard X-rays are primarily emitted from dense, thick-target regions in the lower atmosphere, but the electrons are understood to be accelerated higher in the corona. Various processes can distort the X-ray spectrum or the energy distribution of electrons before they reach the thick-target region. After briefly reviewing the processes that affect the X-ray spectrum and the electron distribution, I will describe recent results from a study of flare spectra from RHESSI to determine the importance of these processes in inferring the energy distribution of accelerated electrons.

  1. Z-pinches as intense x-ray sources for high energy density physics applications

    NASA Astrophysics Data System (ADS)

    Matzen, M. Keith

    1996-11-01

    Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example, currents of 6 to 8 MA with a risetime of less than 50 ns are driven through cylindrically-symmetric loads (typically gas jets, arrays of wires, thin foils, or low density foams), producing implosions velocities as high as 100 cm/μs and x-ray energies as high as 500 kJ. The keV component of the resulting x-ray spectrum has been used for many years as a source for material response studies. Alternatively, the x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a large cylindrical radiation case (a hohlraum). These large volume ( 6000 mm^3), long-lived ( 20 ns) radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Magneto-Rayleigh-Taylor instabilities and load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulsewidths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using uniform-fill gas puff loads or by using wire arrays with as many a 192 wires. These techniques produced significant improvements in the pinched plasma quality, reproducibility, and x-ray output power. X-ray pulsewidths of less than 5 ns and peak powers of 75?10 TW have been achieved with arrays of 120 tungsten wires. These powers represent greater than a factor of three in power amplification over the electrical power of the accelerator, and are a record for x-ray powers in the

  2. Shadowing of the Soft X-ray Background and the Distribution of Hot Gas in the Local Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Labov, Simon E.; Craig, William W.; Kahn, Steven M.

    1993-12-01

    The underlying mechanism responsible for variations in the observed 1/4 keV X-ray background is not well understood. Measurements of soft X-ray shadows cast by clumps of neutral material provide a direct method of determining the spatial distribution of the hot gas responsible for the soft X-ray background. The observed contrast of an X-ray shadow depends on the density and size of the cool absorbing cloud, and on the amount of foreground and background soft X-ray emitting gas. We present here a dramatic example of this shadowing effect as observed by the ROSAT X-ray telescope and position sensitive proportional counter (PSPC). The shadow discussed here is particularly dark with high contrast indicating that the vast majority of the X-ray emitting gas in this direction extends beyond the cloud. This work was supported by the NASA ROSAT Guest Observer Program under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

  3. A reassessment of absolute energies of the x-ray L lines of lanthanide metals

    NASA Astrophysics Data System (ADS)

    Fowler, J. W.; Alpert, B. K.; Bennett, D. A.; Doriese, W. B.; Gard, J. D.; Hilton, G. C.; Hudson, L. T.; Joe, Y.-I.; Morgan, K. M.; O'Neil, G. C.; Reintsema, C. D.; Schmidt, D. R.; Swetz, D. S.; Szabo, C. I.; Ullom, J. N.

    2017-08-01

    We introduce a new technique for determining x-ray fluorescence line energies and widths, and we present measurements made with this technique of 22 x-ray L lines from lanthanide-series elements. The technique uses arrays of transition-edge sensors, microcalorimeters with high energy-resolving power that simultaneously observe both calibrated x-ray standards and the x-ray emission lines under study. The uncertainty in absolute line energies is generally less than 0.4 eV in the energy range of 4.5 keV to 7.5 keV. Of the seventeen line energies of neodymium, samarium, and holmium, thirteen are found to be consistent with the available x-ray reference data measured after 1990; only two of the four lines for which reference data predate 1980, however, are consistent with our results. Five lines of terbium are measured with uncertainties that improve on those of existing data by factors of two or more. These results eliminate a significant discrepancy between measured and calculated x-ray line energies for the terbium L l line (5.551 keV). The line widths are also measured, with uncertainties of 0.6 eV or less on the full-width at half-maximum in most cases. These measurements were made with an array of approximately one hundred superconducting x-ray microcalorimeters, each sensitive to an energy band from 1 keV to 8 keV. No energy-dispersive spectrometer has previously been used for absolute-energy estimation at this level of accuracy. Future spectrometers, with superior linearity and energy resolution, will allow us to improve on these results and expand the measurements to more elements and a wider range of line energies.

  4. Low-photon-energy plasma flash x-ray generator (LPFXG-2002)

    NASA Astrophysics Data System (ADS)

    Komatsu, Makoto; Sato, Eiichi; Hayasi, Yasuomi; Usuki, Tatsumi; Sato, Koetsu; Tanaka, Etsuro; Mori, Hidezo; Ojima, Hidenori; Takayama, Kazuyoshi; Ido, Hideaki

    2003-07-01

    In this study, we have made a low photon energy flash x-ray generator with a titanium target and have measured the radiographic characteristics. The flash x-ray generator consists of a high-voltage power supply, a high-voltage condenser, a turbo molecular pump and a flash x-ray tube. The condenser is charged up to about 30 kV, and the electric charges in the condenser are discharged to the tube after triggering the cathode. The linear plasma x-ray source forms from the target evaporation, and then the flash x-rays are generated from the plasma in the axial direction. K-series emission of titanium has been confirmed in experiments qualitatively and characteristics of the generator have been measured. K-series x-ray of titanium had a high resolution and enable us to take radiographs of a thin rabbit's ear clearly using the CR (Computed Radiography) system. The effect of titanium on the target of the soft flash x-ray tube has been indicated accordingly.

  5. The role of x-ray Swank factor in energy-resolving photon-counting imaging

    SciTech Connect

    Tanguay, Jesse; Kim, Ho Kyung; Cunningham, Ian. A.

    2010-12-15

    Purpose: Energy-resolved x-ray imaging has the potential to improve contrast-to-noise ratio by measuring the energy of each interacting photon and applying optimal weighting factors. The success of energy-resolving photon-counting (EPC) detectors relies on the ability of an x-ray detector to accurately measure the energy of each interacting photon. However, the escape of characteristic emissions and Compton scatter degrades spectral information. This article makes the theoretical connection between accuracy and imprecision in energy measurements with the x-ray Swank factor for a-Se, Si, CdZnTe, and HgI{sub 2}-based detectors. Methods: For a detector that implements adaptive binning to sum all elements in which x-ray energy is deposited for a single interaction, energy imprecision is shown to depend on the Swank factor for a large element with x rays incident at the center. The response function for each converter material is determined using Monte Carlo methods and used to determine energy accuracy, Swank factor, and relative energy imprecision in photon-energy measurements. Results: For each material, at energies below the respective K edges, accuracy is close to unity and imprecision is only a few percent. Above the K-edge energies, characteristic emission results in a drop in accuracy and precision that depends on escape probability. In Si, and to some extent a-Se, Compton-scatter escape also degrades energy precision with increasing energy. The influence of converter thickness on energy accuracy and imprecision is modest for low-Z materials but becomes important when using high-Z materials at energies greater than the K-edge energies. Conclusions: Accuracy and precision in energy measurements by EPC detectors are determined largely by the energy-dependent x-ray Swank factor. Modest decreases in the Swank factor (5%-15%) result in large increases in relative imprecision (30%-40%).

  6. The role of x-ray Swank factor in energy-resolving photon-counting imaging.

    PubMed

    Tanguay, Jesse; Kim, Ho Kyung; Cunningham, Ian A

    2010-12-01

    Energy-resolved x-ray imaging has the potential to improve contrast-to-noise ratio by measuring the energy of each interacting photon and applying optimal weighting factors. The success of energy-resolving photon-counting (EPC) detectors relies on the ability of an x-ray detector to accurately measure the energy of each interacting photon. However, the escape of characteristic emissions and Compton scatter degrades spectral information. This article makes the theoretical connection between accuracy and imprecision in energy measurements with the x-ray Swank factor for a-Se, Si, CdZnTe, and HgI2-based detectors. For a detector that implements adaptive binning to sum all elements in which x-ray energy is deposited for a single interaction, energy imprecision is shown to depend on the Swank factor for a large element with x rays incident at the center. The response function for each converter material is determined using Monte Carlo methods and used to determine energy accuracy, Swank factor, and relative energy imprecision in photon-energy measurements. For each material, at energies below the respective K edges, accuracy is close to unity and imprecision is only a few percent. Above the K-edge energies, characteristic emission results in a drop in accuracy and precision that depends on escape probability. In Si, and to some extent a-Se, Compton-scatter escape also degrades energy precision with increasing energy. The influence of converter thickness on energy accuracy and imprecision is modest for low-Z materials but becomes important when using high-Z materials at energies greater than the K-edge energies. Accuracy and precision in energy measurements by EPC detectors are determined largely by the energy-dependent x-ray Swank factor. Modest decreases in the Swank factor (5%-15%) result in large increases in relative imprecision (30%-40%).

  7. The High-Energy X-ray Probe (HEX-P)

    NASA Astrophysics Data System (ADS)

    Madsen, Kristin; Harrison, Fiona; Stern, Daniel; Grefenstette, Brian; Rana, Vikram; Miyasaka, Hiromasa

    2017-08-01

    The High-Energy X-ray Probe (HEX-P) is a probe-class (~$500M) next-generation high-energy X-ray observatory with broadband (2-200 keV) response and ~40 times the sensitivity of any previous mission in the 10-80 keV band, and >500 times the sensitivity of any previous mission in the 80-200 keV band. Intended to launch contemporaneously with Athena, HEX-P will provide fundamental new discoveries that range from resolving ~90% of the X-ray background at its peak, to measuring the cosmic evolution of black hole spin, to studying faint X-ray populations in nearby galaxies. Based on NuSTAR heritage, HEX-P requires only modest technology development, and could easily be executed within the next decade.

  8. MeV-energy x rays from inverse compton scattering with laser-wakefield accelerated electrons.

    PubMed

    Chen, S; Powers, N D; Ghebregziabher, I; Maharjan, C M; Liu, C; Golovin, G; Banerjee, S; Zhang, J; Cunningham, N; Moorti, A; Clarke, S; Pozzi, S; Umstadter, D P

    2013-04-12

    We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (>200  MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×10(7), the source size was 5  μm, and the beam divergence angle was ∼10  mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration).

  9. Compact energy dispersive X-ray microdiffractometer for diagnosis of neoplastic tissues

    NASA Astrophysics Data System (ADS)

    Sosa, C.; Malezan, A.; Poletti, M. E.; Perez, R. D.

    2017-08-01

    An energy dispersive X-ray microdiffractometer with capillary optics has been developed for characterizing breast cancer. The employment of low divergence capillary optics helps to reduce the setup size to a few centimeters, while providing a lateral spatial resolution of 100 μm. The system angular calibration and momentum transfer resolution were assessed by a detailed study of a polycrystalline reference material. The performance of the system was tested by means of the analysis of tissue-equivalent samples previously characterized by conventional X-ray diffraction. In addition, a simplified correction model for an appropriate comparison of the diffraction spectra was developed and validated. Finally, the system was employed to evaluate normal and neoplastic human breast samples, in order to determine their X-ray scatter signatures. The initial results indicate that the use of this compact energy dispersive X-ray microdiffractometer combined with a simplified correction procedure is able to provide additional information to breast cancer diagnosis.

  10. New developments in fabrication of high-energy-resolution analyzers for inelastic x-ray spectroscopy.

    SciTech Connect

    Said, A. H.; Sinn, H.; Divan, R.

    2011-05-01

    In this work new improvements related to the fabrication of spherical bent analyzers for 1 meV energy-resolution inelastic X-ray scattering spectroscopy are presented. The new method includes the use of a two-dimensional bender to achieve the required radius of curvature for X-ray analyzers. The advantage of this method is the ability to monitor the focus during bending, which leads to higher-efficiency analyzers.

  11. New developments in fabrication of high-energy-resolution analyzers for inelastic X-ray spectroscopy

    PubMed Central

    Said, Ayman H.; Sinn, Harald; Divan, Ralu

    2011-01-01

    In this work new improvements related to the fabrication of spherical bent analyzers for 1 meV energy-resolution inelastic X-ray scattering spectroscopy are presented. The new method includes the use of a two-dimensional bender to achieve the required radius of curvature for X-ray analyzers. The advantage of this method is the ability to monitor the focus during bending, which leads to higher-efficiency analyzers. PMID:21525659

  12. New developments in fabrication of high-energy-resolution analyzers for inelastic X-ray spectroscopy.

    PubMed

    Said, Ayman H; Sinn, Harald; Divan, Ralu

    2011-05-01

    In this work new improvements related to the fabrication of spherical bent analyzers for 1 meV energy-resolution inelastic X-ray scattering spectroscopy are presented. The new method includes the use of a two-dimensional bender to achieve the required radius of curvature for X-ray analyzers. The advantage of this method is the ability to monitor the focus during bending, which leads to higher-efficiency analyzers.

  13. Quantitative Electron Probe Microanalysis Using a Scanning Electron Microscope and an X-Ray Energy Spectrometer.

    DTIC Science & Technology

    1980-04-01

    necessary to solve the ZAF cor- rections in an iterative manner similar to that used by J . Colby 13in the Magic IV programme . In that programme the...Combined with an Energy Dispersive X-ray Analyzer for Quantitative Analysis", X-ray Spectrometry, 2, 1973. 10. Green, L.: Journ. of Phys. E. Scient ... Instrum ., 2, (3), 1973. 11. Wodke, Norbert F. and Schamber, Frederick, MS 885 Super ML Operation and Programme Description Version 1, Unpublished, Tracor

  14. Thermal expansion in UO 2 determined by high-energy X-ray diffraction

    SciTech Connect

    Guthrie, M.; Benmore, C. J.; Skinner, L. B.; Alderman, O. L. G.; Weber, J. K. R.; Parise, J. B.; Williamson, M.

    2016-10-01

    Here we present crystallographic analyses of high-energy X-ray diffraction data on polycrystalline UO2 up to the melting temperature. The Rietveld refinements of our X-ray data are in agreement with previous measurements, but are systematically located around the upper bound of their uncertainty, indicating a slightly steeper trend of thermal expansion compared to established values. This observation is consistent with recent first principles calculations.

  15. Thermal expansion in UO2 determined by high-energy X-ray diffraction

    DOE PAGES

    Guthrie, M.; Benmore, C. J.; Skinner, L. B.; ...

    2016-06-24

    In this study, we present crystallographic analyses of high-energy X-ray diffraction data on polycrystalline UO2 up to the melting temperature. The Rietveld refinements of our X-ray data are in agreement with previous measurements, but are systematically located around the upper bound of their uncertainty, indicating a slightly steeper trend of thermal expansion compared to established values. This observation is consistent with recent first principles calculations.

  16. Novel x-ray imaging diagnostics of high-energy nanosecond pulse accelerators

    NASA Astrophysics Data System (ADS)

    Smith, Graham W.; Beutler, David E.; Bell, John D.; Seymour, Calvin L. G.; Hohlfelder, Robert J.; Gallegos, Roque R.; Dudley, John

    2005-03-01

    Pioneering x-ray imaging has been undertaken on a number of AWE"s and Sandia National Laboratories" radiation effects x-ray simulators. These simulators typically yield a single very short (<50ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad(Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.1 to 2.5MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and a preliminary evaluation of the capability of the spectrometer are presented. Further, a novel time resolved imaging system is described that captures a sequence of high spatial resolution temporal images, with zero interframe time, in the nanosecond timeframe, of our source x-rays.

  17. The energy spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters

    NASA Astrophysics Data System (ADS)

    Trümper, J. E.; Zezas, A.; Ertan, Ü.; Kylafis, N. D.

    2010-07-01

    Context. Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) exhibit characteristic X-ray luminosities (both soft and hard) of around 1035 erg s-1 and characteristic power-law, hard X-ray spectra extending to about 200 keV. Two AXPs also exhibit pulsed radio emission. Aims: Assuming that AXPs and SGRs accrete matter from a fallback disk, we attempt to explain both the soft and the hard X-ray emission as the result of the accretion process. We also attempt to explain their radio emission or the lack of it. Methods: We test the hypothesis that the power-law, hard X-ray spectra are produced in the accretion flow mainly by bulk-motion Comptonization of soft photons emitted at the neutron star surface. Fallback disk models invoke surface dipole magnetic fields of 1012 - 1013 G, which is what we assume here. Results: Unlike normal X-ray pulsars, for which the accretion rate is highly super-Eddington, the accretion rate is approximately Eddington in AXPs and SGRs and thus the bulk-motion Comptonization operates efficiently. As an illustrative example we reproduce both the hard and the soft X-ray spectra of AXP 4U 0142+61 well using the XSPEC package compTB. Conclusions: Our model seems to explain both the hard and the soft X-ray spectra of AXPs and SGRs, as well as their radio emission or the lack of it, in a natural way. It might also explain the short bursts observed in these sources. On the other hand, it cannot explain the giant X-ray outbursts observed in SGRs, which may result from the conversion of magnetic energy in local multipole fields.

  18. Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

    SciTech Connect

    Takeda, Tohoru; Wu Jin; Tsuchiya, Yoshinori; Lwin, Thet-Thet; Itai, Yuji; Yoneyama, Akio; Hyodo, Kazuyuki

    2004-05-12

    Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

  19. Radio and X-ray Diagnostics of Energy Release in Solar Flares

    NASA Astrophysics Data System (ADS)

    Chen, Bin

    2013-07-01

    Solar flares involve catastrophic release of magnetic energy previously stored in the Sun's corona. This dissertation focuses on studies of radio and hard X-ray emissions as diagnostics of energy release in flares. A major part of the dissertation is exploiting spatially resolved dynamic spectroscopy to study coherent radio bursts. The Frequency-Agile Solar Radiotelescope Subsystem Testbed, a three-element radio interferometer, provides the first opportunity of doing such studies on zebra-pattern bursts. The observations allow us to identify the relevant emission mechanism, enabling diagnostics of the plasma parameters in the source. With the help of coronal magnetic field extrapolations, the source is placed into a three-dimensional magnetic field configuration and its relation to the energy release is clarified. The next part of the dissertation discusses the "solar mode" commissioning of the upgraded Karl G. Jansky Very Large Array (VLA). As a general purpose telescope, special provisions should be made for the VLA to enable solar observations. Based on the test results on the VLA's hardware, solar observing and calibration strategies are developed. Now the VLA is capable of observing the Sun with simultaneous imaging and dynamic spectroscopy over a large bandwidth at high spatial, spectral, and temporal resolutions. The upgraded VLA is used to observe decimetric type III radio bursts, which are the radio signature of propagating fast electron beams produced in flares. The new observing technique allows detailed trajectories of these electron beams to be derived. Combined with multi-wavelength observations, the properties of the energy release site, electron beams, and the surrounding coronal medium are deduced. The dissertation also presents a study on coronal hard X-ray/gamma-ray sources. Rather extreme conditions are needed to account for some observed coronal hard X-ray/gamma-ray sources using the usually-assumed non-thermal bremsstrahlung emission. This

  20. Material depth reconstruction method of multi-energy X-ray images using neural network.

    PubMed

    Lee, Woo-Jin; Kim, Dae-Seung; Kang, Sung-Won; Yi, Won-Jin

    2012-01-01

    With the advent of technology, multi-energy X-ray imaging is promising technique that can reduce the patient's dose and provide functional imaging. Two-dimensional photon-counting detector to provide multi-energy imaging is under development. In this work, we present a material decomposition method using multi-energy images. To acquire multi-energy images, Monte Carlo simulation was performed. The X-ray spectrum was modeled and ripple effect was considered. Using the dissimilar characteristics in energy-dependent X-ray attenuation of each material, multiple energy X-ray images were decomposed into material depth images. Feedforward neural network was used to fit multi-energy images to material depth images. In order to use the neural network, step wedge phantom images were used for training neuron. Finally, neural network decomposed multi-energy X-ray images into material depth image. To demonstrate the concept of this method, we applied it to simulated images of a 3D head phantom. The results show that neural network method performed effectively material depth reconstruction.

  1. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    NASA Technical Reports Server (NTRS)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  2. Edge-enhanced imaging obtained with very broad energy band x-rays

    SciTech Connect

    Taibi, A.; Cardarelli, P.; Di Domenico, G.; Marziani, M.; Gambaccini, M.; Hanashima, T.; Yamada, H.

    2010-04-05

    We demonstrate both theoretically and experimentally that edge-enhancement effects are produced when objects, in contact with the x-ray detector, are imaged by using very broad x-ray spectra. Radiographs of thin Al objects have been obtained with a table-top synchrotron source which generates x-rays in the energy range from a few kilo-electron-volts up to 6 MeV. Edge-enhancement effects arise from the combination of x-ray absorption (kilo-electron-volt part of the spectrum) and secondary particle emission (mega-electron-volt part of the spectrum) within the sample. The exact contribution of absorption and emission profiles in the edge-enhanced images has been calculated via Monte Carlo simulation.

  3. Multiple energy x-ray holography: Incident-radiation polarization effects

    SciTech Connect

    Len, P.M.; Gog, T.; Novikov, D.; Eisenhower, R.A.; Materlik, G.; Fadley, C.S. |

    1997-07-01

    Multiple energy x-ray holography (MEXH) measures both phase and amplitude information for x rays scattered from an incident reference beam, from which three-dimensional atomic images can be directly reconstructed. The angular distribution of the x-ray scattering is highly dependent on the polarization direction via the Thomson scattering cross section. We consider here the effect of incident x-ray polarization on images of Fe atoms reconstructed from theoretical and experimental MEXH data for {alpha}-Fe{sub 2}O{sub 3}(001) (hematite). We also illustrate such polarization effects theoretically in the enhancement of specific atomic structural information of ideal Fe trimers, and a Ge {delta}-layer buried in Si(001), where the use of different polarization modes and experimental geometries is found to strongly influence atomic images. {copyright} {ital 1997} {ital The American Physical Society}

  4. Proposal for an x-ray free electron laser oscillator with intermediate energy electron beam.

    PubMed

    Dai, Jinhua; Deng, Haixiao; Dai, Zhimin

    2012-01-20

    Harmonic lasing of low-gain free electron laser oscillators has been experimentally demonstrated in the terahertz and infrared regions. Recently, the low-gain oscillator has been reconsidered as a promising candidate for hard x-ray free electron lasers, through the use of high reflectivity, high-resolution x-ray crystals. In this Letter, it is proposed to utilize a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting, to enable harmonic lasing of the x-ray free electron laser oscillator, and hence allow the generation of hard x-ray radiation at a reduced electron beam energy. Results show that fully coherent free electron laser radiation with megawatt peak power, in the spectral region of 10-25 keV, can be generated with a 3.5 GeV electron beam.

  5. a-Si:H TFT-silicon hybrid low-energy x-ray detector

    DOE PAGES

    Shin, Kyung -Wook; Karim, Karim S.

    2017-03-15

    Direct conversion crystalline silicon X-ray imagers are used for low-energy X-ray photon (4-20 keV) detection in scientific research applications such as protein crystallography. In this paper, we demonstrate a novel pixel architecture that integrates a crystalline silicon X-ray detector with a thin-film transistor amorphous silicon pixel readout circuit. We describe a simplified two-mask process to fabricate a complete imaging array and present preliminary results that show the fabricated pixel to be sensitive to 5.89-keV photons from a low activity Fe-55 gamma source. Furthermore, this paper presented can expedite the development of high spatial resolution, low cost, direct conversion imagers formore » X-ray diffraction and crystallography applications.« less

  6. Evaluation of Exposure From a Low Energy X-Ray Device Using Thermoluminescent Dosimeters

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Harris, William S., Jr.

    1997-01-01

    The exposure from an electron beam welding device was evaluated using thermoluminescent dosimeters (TLDs). The device generated low energy X-rays which the current dose equivalent conversion algorithm was not designed to evaluate making it necessary to obtain additional information relating to TLD operation at the photon energies encountered with the device. This was accomplished by performing irradiations at the National Institute of Standards and Technology (NIST) using low energy X-ray techniques. The resulting data was used to determine TLD badge response for low energy X-rays and to establish the relationship between TLD element response and the dose equivalent at specific depths in tissue for these photon energies. The new energy/dose equivalent calibration data was used to calculate the shallow and eye dose equivalent of badges exposed to the device.

  7. Runaway electron energy measurement using hard x-ray spectroscopy in "Damavand" tokamak.

    PubMed

    Rasouli, C; Iraji, D; Farahbod, A H; Akhtari, K; Rasouli, H; Modarresi, H; Lamehi, M

    2009-01-01

    Set of experiments has been developed to study existing runaway electrons in "Damavand" tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

  8. Runaway electron energy measurement using hard x-ray spectroscopy in 'Damavand' tokamak

    SciTech Connect

    Rasouli, C.; Farahbod, A. H.; Rasouli, H.; Lamehi, M.; Iraji, D.; Akhtari, K.; Modarresi, H.

    2009-01-15

    Set of experiments has been developed to study existing runaway electrons in ''Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

  9. HEAO 1 observations of high-energy X-rays from 3C273. [quasar emissions

    NASA Technical Reports Server (NTRS)

    Primini, F. A.; Cooke, B. A.; Dobson, C. A.; Howe, S. K.; Scheepmaker, A.; Wheaton, W. A.; Lewin, W. H. G.; Baity, W. A.; Gruber, D. E.; Matteson, J. L.

    1979-01-01

    The first detection of high energy (13 to 120 keV) X rays from the quasar 3C273, made by the HEAO 1 satellite, is reported. Observations were made with the 13 to 180 keV slat collimated detectors of the high energy X-ray and low energy gamma-ray (A4) experiment during December 1977-January 1978 and June-July 1978. Results are consistent with the previously observed X-ray flux variability on a scale of months. Photon count rates are presented for each of five energy bands and count rate and photon spectra for the June through July 1978 observations are derived. A comparison of the data obtained with that at lower X-ray energies and higher gamma-ray energies indicates that there is an overall spectral steepening from low to high energies and a possible break near 20 keV, which may be due to the gamma rays originating from a different region than that of the X rays.

  10. Compensational scintillation detector with a flat energy response for flash X-ray measurements

    SciTech Connect

    Chen Liang; Quan Lin; Zhang Zhongbing; Ouyang Xiaoping; Liu Bin; Liu Jinliang

    2013-01-15

    To measure the intensity of flash X-ray sources directly, a novel scintillation detector with a fast time response and flat energy response is developed by combining film scintillators of doped ZnO crystal and fast organic scintillator together. Through compensation design, the dual-scintillator detector (DSD) achieved a flat energy response to X-rays from tens of keV to several MeV, and sub-nanosecond time response by coupling to ultrafast photo-electronic devices. A prototype detector was fabricated according to the theoretical design; it employed ZnO:In and EJ228 with thicknesses of 0.3 mm and 0.1 mm, respectively. The energy response of this detector was tested on monoenergetic X-ray and {gamma}-ray sources. The detector performs very well with a sensitivity fluctuation below 5% for 8 discrete energy points within the 40-250 keV energy region and for other energies of 662 keV and 1.25 MeV as well, showing good accordance with the theoretical design. Additionally, the detector works properly for the application to the flash X-ray radiation field absolute intensity measurement. This DSD may be very useful for the diagnosis of time-resolved dynamic physical processes of flash X-ray sources without knowing the exact energy spectrum.

  11. ''Hybrid'' calibrations of a Dual Energy X-ray Scanner for material testing

    NASA Astrophysics Data System (ADS)

    Kröger, C.; Bartle, C. M.; West, J. G.

    2006-05-01

    Conventional x-ray tubes produce a fan-shaped x-ray beam covering a large spectrum of energies, which is why the fundamental law of x-ray attenuation is not readily applicable. As the mathematical formulation of the problem would be too cumbersome, calibrations using well-defined objects are carried out, which in turn allow the use of multienergy x-rays for measurements. Occasionally, such calibrations may not lead to the desired results. This could be for instance due to an insensitivity of x-rays towards low atomic number elements. Here we present such a case on hand the example of raw natural fibre. The DEXA parameters correlated with the fibre parameter wool base, but show distinct correlation for geographical regions of the origin of the wool. A calibration that is valid independently of geographical origin can be achieved by including independently measured parameters of the calibration body. We demonstrate a successful calibration that uses dual energy x-ray scanning technology as well as a size parameter of the fibre in the regression equation.

  12. Plasma Diagnostic Calibration and Characterizations with High Energy X-rays

    SciTech Connect

    Zaheer Ali

    2009-06-05

    National Security Technologies’ High Energy X-ray (HEX) Facility is unique in the U.S. Department of Energy complex. The HEX provides fluorescent X-rays of 5 keV to 100 keV with fluence of 10^5–10^6 photons/cm^2/second at the desired line energy. Low energy lines can be filtered, and both filters and fluorescers can be changed rapidly. We present results of calibrating image plates (sensitivity and modulation transfer function), a Bremsstrahlung spectrometer (stacked filters and image plates), and the National Ignition Facility’s Filter- Fluorescer Experiment (FFLEX) high energy X-ray spectrometer. We also show results of a scintillator light yield and alignment study for a neutron imaging system.

  13. Energy calibration of the pixels of spectral X-ray detectors.

    PubMed

    Panta, Raj Kumar; Walsh, Michael F; Bell, Stephen T; Anderson, Nigel G; Butler, Anthony P; Butler, Philip H

    2015-03-01

    The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have developed a technique for calibrating the energy response of individual pixels using X-ray fluorescence generated by metallic targets directly irradiated with polychromatic X-rays, and additionally γ-rays from (241)Am. This technique was used to measure the energy response of individual pixels in CdTe-Medipix3RX by characterizing noise performance, threshold dispersion, gain variation and spectral resolution. The comparison of these two techniques shows the energy difference of 1 keV at 59.5 keV which is less than the spectral resolution of the detector (full-width at half-maximum of 8 keV at 59.5 keV). Both techniques can be used as quality control tools in a pre-clinical multi-energy CT scanner using spectral X-ray detectors.

  14. Pulse energy measurement at the hard x-ray laser in Japan

    SciTech Connect

    Kato, M.; Tanaka, T.; Saito, N.; Kurosawa, T.; Richter, M.; Sorokin, A. A.; Tiedtke, K.; Kudo, T.; Yabashi, M.; Tono, K.; Ishikawa, T.

    2012-07-09

    The pulse energies of a free electron laser have accurately been measured in the hard x-ray spectral range. In the photon energy regime from 4.4 keV to 16.8 keV, pulse energies up to 100 {mu}J were obtained at the hard x-ray laser facility SACLA (SPring-8 Angstrom Compact free-electron LAser). Two independent methods, using a cryogenic radiometer and a gas monitor detector, were applied and agreement within 3.3% was achieved. Based on our validated pulse energy measurement, a SACLA online monitor detector could be calibrated for all future experiments.

  15. 20-element HgI[sub 2] energy dispersive x-ray array detector system

    SciTech Connect

    Iwanczyk, J.S.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J. ); Hedman, B.; Hodgson, K.O. . Stanford Synchrotron Radiation Lab.); Patt, B.E. )

    1992-10-01

    This paper describes recent progress in the development of HgI[sub 2] energy dispersive x-ray arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20-element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K[sub alpha]) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken form diluted samples simulating proteins with nickel.

  16. 20 element HgI sub 2 energy dispersive x-ray array detector system

    SciTech Connect

    Iwanczyk, J.A.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J. ); Hedman, B.; Hodgson, K.O. . Stanford Synchrotron Radiation Lab.); Patt, B.E. )

    1991-01-01

    This paper describes recent progress in the development of HgI{sub 2} energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K{sub a}) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

  17. 20 element HgI{sub 2} energy dispersive x-ray array detector system

    SciTech Connect

    Iwanczyk, J.A.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J.; Hedman, B.; Hodgson, K.O.; Patt, B.E.

    1991-12-31

    This paper describes recent progress in the development of HgI{sub 2} energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K{sub a}) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

  18. Measurement of the energy dependence of X-ray-induced decomposition of potassium chlorate.

    PubMed

    Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

    2013-03-21

    We report the first measurements of the X-ray induced decomposition of KClO3 as a function of energy in two experiments. KClO3 was pressurized to 3.5 GPa and irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 35 keV in 5 keV increments. A systematic increase in the decomposition rate as the energy was decreased was observed, which agrees with the 1/E(3) trend for the photoelectric process, except at the lowest energy studied. A second experiment was performed to access lower energies (10 and 12 keV) using a beryllium gasket; suggesting an apparent resonance near 15 keV or 0.83 Ǻ maximizing the chemical decomposition rate. A third experiment was performed using KIO3 to ascertain the anionic dependence of the decomposition rate, which was observed to be far slower than in KClO3, suggesting that the O-O distance is the critical factor in chemical reactions. These results will be important for more efficiently initiating chemical decomposition in materials using selected X-ray wavelengths that maximize decomposition to aid useful hard X-ray-induced chemistry and contribute understanding of the mechanism of X-ray-induced decomposition of the chlorates.

  19. Analytic model of energy-absorption response functions in compound X-ray detector materials.

    PubMed

    Yun, Seungman; Kim, Ho Kyung; Youn, Hanbean; Tanguay, Jesse; Cunningham, Ian A

    2013-10-01

    The absorbed energy distribution (AED) in X-ray imaging detectors is an important factor that affects both energy resolution and image quality through the Swank factor and detective quantum efficiency. In the diagnostic energy range (20-140 keV), escape of characteristic photons following photoelectric absorption and Compton scatter photons are primary sources of absorbed-energy dispersion in X-ray detectors. In this paper, we describe the development of an analytic model of the AED in compound X-ray detector materials, based on the cascaded-systems approach, that includes the effects of escape and reabsorption of characteristic and Compton-scatter photons. We derive analytic expressions for both semi-infinite slab and pixel geometries and validate our approach by Monte Carlo simulations. The analytic model provides the energy-dependent X-ray response function of arbitrary compound materials without time-consuming Monte Carlo simulations. We believe this model will be useful for correcting spectral distortion artifacts commonly observed in photon-counting applications and optimal design and development of novel X-ray detectors.

  20. The Einstein Observatory Medium Sensitivity Survey - Optical identifications for a complete sample of X-ray sources

    NASA Technical Reports Server (NTRS)

    Stocke, J. T.; Liebert, J.; Gioia, I. M.; Maccacaro, T.; Griffiths, R. E.; Danziger, I. J.; Kunth, D.; Lub, J.

    1983-01-01

    It is suggested that virtually all the X-ray sources in the Einstein Observatory's Medium Sensitivity Survey flux range can be identified with objects visible on the POSS, on the basis of the complete identification of all sources north of -25 deg declination. There is no evidence for a significant population of 'blank field' X-ray sources at this flux level, and therefore no evidence for any new X-ray source class with very high L(x)/L(v). Most of the quasars detected in the present survey are spectroscopically similar to optical or radio-selected quasars. About 25 percent of the quasar sample, however, had reddish colors, and permitted lines dominated by a narrow-line component. These objects form a second sequence of active galactic nuclei, distinct in their optical properties from the broad line objects.

  1. Room-temperature mercuric iodide spectrometry for low-energy X-rays

    NASA Technical Reports Server (NTRS)

    Kusmiss, J. H.; Barton, J. B.; Huth, G. C.; Economou, T. E.; Turkevich, A. L.; Iwanczyk, J. S.; Dabrowski, A. J.

    1982-01-01

    A discussion of the limits of energy resolution in different energy ranges is given. The energy resolution of a spectrometer is analyzed in terms of the parameters characterizing the crystal, the detector, and the amplification electronics. A high-resolution room-temperature HgI2 spectrometry system was used to measure low-energy X-ray fluorescence spectra. For the MgK-alpha X-ray line the measured resolution was 245 eV (fwhm); the electronic noise linewidth of the system was 225 eV. Alpha-particles were used to excite X-ray fluorescence from low-Z elements separately or in combination. The shape of the photopeaks in the spectra is discussed.

  2. X-ray grating interferometry at photon energies over 180 keV

    SciTech Connect

    Ruiz-Yaniz, M.; Koch, F.; Meyer, P.; Kunka, D.; Mohr, J.; Zanette, I.; Rack, A.; Hipp, A.; Pfeiffer, F.

    2015-04-13

    We report on the implementation and characterization of grating interferometry operating at an x-ray energy of 183 keV. With the possibility to use this technique at high x-ray energies, bigger specimens could be studied in a quantitative way. Also, imaging strongly absorbing specimens will benefit from the advantages of the phase and dark-field signals provided by grating interferometry. However, especially at these high photon energies the performance of the absorption grating becomes a key point on the quality of the system, because the grating lines need to keep their small width of a couple of micrometers and exhibit a greater height of hundreds of micrometers. The performance of high aspect ratio absorption gratings fabricated with different techniques is discussed. Further, a dark-field image of an alkaline multicell battery highlights the potential of high energy x-ray grating based imaging.

  3. Strain Measurements using High Energy White X-rays at SPring-8

    SciTech Connect

    Shobu, T.; Kaneko, H.; Mizuki, J.; Konishi, H.; Shibano, J.; Hirata, T.; Suzuki, K.

    2007-01-19

    The strain in the bulk of a material was evaluated using high energy white X-rays from a synchrotron radiation source at SPring-8. The specimen, which was a 5 mm thick austenitic stainless steel sample (JIS-SUS304L), was subjected to bending. The internal strain was measured using white X-rays, which ranged in energy from 60 keV to 125 keV. Highly accurate internal strain measurements were accomplished by simultaneously using strain data from several lattice planes of {alpha} -Fe. Furthermore, utilizing diffracted beams with a high energy, a high peak count, and a profile similar to a Gaussian distribution decreased the error of the strain measurement The results indicated that high energy white X-rays can effectively measure the internal strain at a millimeter depth.

  4. Design and Implementation of an Acoustic X-ray Detector to Measure the LCLS Beam Energy

    SciTech Connect

    Loos, Jennifer L.; /San Jose State U. /SLAC

    2010-08-25

    On April 11, 2009, first light was seen from LCLS. The present apparatus being used to measure the x-ray beam energy is the Total Energy Sensor which uses a suite of thermal sensors. Another device is needed to cross-check the energy measurements. This new diagnostic tool utilizes radiation acoustic phenomena to determine the x-ray beam energy. A target is hit by the x-rays from the beam, and a voltage is generated in two piezoelectric sensors attached to the target in response to the consequent deformation. Once the voltage is known, the power can be obtained. Thermal sensors will also be attached to the target for calibration purposes. Material selection and design were based on: durability, ultra-high vacuum compatibility, safety and thermal properties. The target material was also chosen for its acoustic properties which were determined from tests using a frequency generator and laser. Initial tests suggest the device will function as anticipated.

  5. Comparison between absorbed dose to water standards established by water calorimetry at the LNE-LNHB and by application of international air-kerma based protocols for kilovoltage medium energy x-rays.

    PubMed

    Perichon, N; Rapp, B; Denoziere, M; Daures, J; Ostrowsky, A; Bordy, J-M

    2013-05-07

    Nowadays, the absorbed dose to water for kilovoltage x-ray beams is determined from standards in terms of air-kerma by application of international dosimetry protocols. New standards in terms of absorbed dose to water has just been established for these beams at the LNE-LNHB, using water calorimetry, at a depth of 2 cm in water in accordance with protocols. The aim of this study is to compare these new standards in terms of absorbed dose to water, to the dose values calculated from the application of four international protocols based on air-kerma standards (IAEA TRS-277, AAPM TG-61, IPEMB and NCS-10). The acceleration potentials of the six beams studied are between 80 and 300 kV with half-value layers between 3.01 mm of aluminum and 3.40 mm of copper. A difference between the two methods smaller than 2.1% was reported. The standard uncertainty of water calorimetry being below 0.8%, and the one associated with the values from protocols being around 2.5%, the results are in good agreement. The calibration coefficients of some ionization chambers in terms of absorbed dose to water, established by application of calorimetry and air-kerma based dosimetry protocols, were also compared. The best agreement with the calibration coefficients established by water calorimetry was found for those established with the AAPM TG-61 protocol.

  6. Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

    PubMed Central

    Slater, Thomas J. A.; Lewis, Edward A.; Haigh, Sarah J.

    2016-01-01

    Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction. Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of > 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm. Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed. PMID:27403838

  7. Low-energy X-ray detection with an in-vacuum PILATUS detector

    NASA Astrophysics Data System (ADS)

    Marchal, Julien; Luethi, Benjamin; Ursachi, Catalin; Mykhaylyk, Vitaliy; Wagner, Armin

    2011-11-01

    The feasibility of using PILATUS single-X-ray-photon counting detectors for long-wavelength macromolecular crystallography was investigated by carrying out a series of experiments at Diamond Light Source. A water-cooled PILATUS 100k detector was tested in vacuum with monochromatic 3 keV X-rays on the Diamond test beamline B16. Effects of detector cooling on noise performance, energy calibration and threshold trimming were investigated. When detecting 3 keV X-rays, the electronic noise of the analogue output of pixel preamplifiers forces the threshold to be set at a higher level than the 50% energy level recommended to minimize charge-sharing effects. The influence of threshold settings at low X-ray energy was studied by characterizing the detector response to a collimated beam of 3 keV X-rays scanned across several pixels. The relationship between maximum count rate and minimum energy threshold was investigated separately for various detector gain settings.

  8. A theoretical analysis of reflection of X-rays from water at energies relevant for diagnostics

    SciTech Connect

    Arsenovic, Dusan; Davidovic, Dragomir M.; Vukanic, Jovan

    2003-01-24

    The reflection of X-rays from a semi-infinite water target, for energies used in X-ray diagnostics, is treated by the analog Monte Carlo simulation. In the developed procedure it was possible to calculate separately contributions of photons scattered, before reflection, fixed number of times with target electrons. It turned out that multiple collision type of reflection dominates at all energies investigated, whenever the absorption is small. The same process was also treated analytically as the classical albedo problem for isotropic scattering without energy loss. Very good agreement of results of the two approaches is obtained.

  9. Development of a low-energy x-ray camera for the imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation for range estimation.

    PubMed

    Ando, Koki; Yamaguchi, Mitsutaka; Yamamoto, Seiichi; Toshito, Toshiyuki; Kawachi, Naoki

    2017-06-21

    Imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation is a possible method for measurement of the proton beam distribution in phantom. However, it is not clear that the method is used for range estimation of protons. For this purpose, we developed a low-energy x-ray camera and conducted imaging of the bremsstrahlung x-ray produced during irradiation of proton beams. We used a 20 mm  ×  20 mm  ×  1 mm finely grooved GAGG scintillator that was optically coupled to a one-inch square high quantum efficiency (HQE)-type position-sensitive photomultiplier tube to form an imaging detector. The imaging detector was encased in a 2 cm-thick tungsten container, and a pinhole collimator was attached to its camera head. After performance of the camera was evaluated, secondary electron bremsstrahlung x-ray imaging was conducted during irradiation of the proton beams for three different proton energies, and the results were compared with Monte Carlo simulation as well as calculated value. The system spatial resolution and sensitivity of the developed x-ray camera with 1.5 mm-diameter pinhole collimator were estimated to be 32 mm FWHM and 5.2  ×  10(-7) for ~35 keV x-ray photons at 100 cm from the collimator surface, respectively. We could image the proton beam tracks by measuring the secondary electron bremsstrahlung x-ray during irradiation of the proton beams, and the ranges for different proton energies could be estimated from the images. The measured ranges from the images were well matched with the Monte Carlo simulation, and slightly smaller than the calculated values. We confirmed that the imaging of the secondary electron bremsstrahlung x-ray emitted during proton irradiation with the developed x-ray camera has the potential to be a new tool for proton range estimations.

  10. Development of a low-energy x-ray camera for the imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation for range estimation

    NASA Astrophysics Data System (ADS)

    Ando, Koki; Yamaguchi, Mitsutaka; Yamamoto, Seiichi; Toshito, Toshiyuki; Kawachi, Naoki

    2017-06-01

    Imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation is a possible method for measurement of the proton beam distribution in phantom. However, it is not clear that the method is used for range estimation of protons. For this purpose, we developed a low-energy x-ray camera and conducted imaging of the bremsstrahlung x-ray produced during irradiation of proton beams. We used a 20 mm  ×  20 mm  ×  1 mm finely grooved GAGG scintillator that was optically coupled to a one-inch square high quantum efficiency (HQE)-type position-sensitive photomultiplier tube to form an imaging detector. The imaging detector was encased in a 2 cm-thick tungsten container, and a pinhole collimator was attached to its camera head. After performance of the camera was evaluated, secondary electron bremsstrahlung x-ray imaging was conducted during irradiation of the proton beams for three different proton energies, and the results were compared with Monte Carlo simulation as well as calculated value. The system spatial resolution and sensitivity of the developed x-ray camera with 1.5 mm-diameter pinhole collimator were estimated to be 32 mm FWHM and 5.2  ×  10-7 for ~35 keV x-ray photons at 100 cm from the collimator surface, respectively. We could image the proton beam tracks by measuring the secondary electron bremsstrahlung x-ray during irradiation of the proton beams, and the ranges for different proton energies could be estimated from the images. The measured ranges from the images were well matched with the Monte Carlo simulation, and slightly smaller than the calculated values. We confirmed that the imaging of the secondary electron bremsstrahlung x-ray emitted during proton irradiation with the developed x-ray camera has the potential to be a new tool for proton range estimations.

  11. Dual-energy x-ray image decomposition by independent component analysis

    NASA Astrophysics Data System (ADS)

    Jiang, Yifeng; Jiang, Dazong; Zhang, Feng; Zhang, Dengfu; Lin, Gang

    2001-09-01

    The spatial distributions of bone and soft tissue in human body are separated by independent component analysis (ICA) of dual-energy x-ray images. It is because of the dual energy imaging modelí-s conformity to the ICA model that we can apply this method: (1) the absorption in body is mainly caused by photoelectric absorption and Compton scattering; (2) they take place simultaneously but are mutually independent; and (3) for monochromatic x-ray sources the total attenuation is achieved by linear combination of these two absorption. Compared with the conventional method, the proposed one needs no priori information about the accurate x-ray energy magnitude for imaging, while the results of the separation agree well with the conventional one.

  12. The application of a microstrip gas counter to energy-dispersive x-ray fluorescence analysis

    SciTech Connect

    Veloso, J.F.C.A.; Santos, J.M.F. dos; Conde, C.A.N.; Morgado, R.E.

    1996-07-01

    Performance characteristics of a microstrip gas counter operated as a x-ray fluorescence spectrometer are reported. Gas amplification as a function of microstrip anode-cathode voltage was measured, and the breakdown threshold voltage was determined in pure xenon. The detector temporal stability and the effect of gas purity were assessed. Energy resolution and linearity, detection efficiency, and uniformity of spatial response in the 2- to 60-keV x-ray energy range were determined from the pulse-height distributions of the fluorescence x-ray spectra induced in a variety of single- and multi-element sample materials. Energy resolution similar to conventional proportional counters was achieved at 6 keV.

  13. Phase-contrast and magnification radiography at diagnostic X-ray energies using a pseudo-microfocus X-ray source

    PubMed Central

    Robson, K J

    2014-01-01

    Objective: To investigate the use of conventional diagnostic X-ray tubes for applications in which specialist microfocus sources are normally required. Methods: A conventional diagnostic X-ray tube was used in conjunction with a range of apertures to investigate improvements in spatial resolution using a line-pairs test object. Phase-contrast effects were investigated by varying source-to-object and object-to-receptor distances using a 2-French catheter as a clinically realistic test object. Results: For magnification radiography using a computed radiography receptor and conventional X-ray tube with a 1-mm nominal focus size, the limiting spatial resolution was improved from 3.55 line-pairs per millimetre, for a conventional contact image, to 5.6 line-pairs per millimetre, for a ×2 magnified view with a 250-µm aperture. For inline phase-contrast radiography, phase contrast enhancement of a 2-French catheter was demonstrated, and the expected trends with variations in source-to-object and object-to-receptor distances were found. Images of a neonatal phantom demonstrated a subtle improvement in visibility of a superimposed 1-French catheter simulating a percutaneously inserted central catheter for no increase in patient radiation dose. Conclusion: Spatial resolution improvement and visible phase contrast can be produced in clinically relevant objects using a pseudo-microfocus geometry at X-ray energies in the normal diagnostic range, using conventional diagnostic X-ray tubes and image receptors. The disadvantages of the proposal are the large distances required to produce phase contrast and limitations imposed by the resulting tube loading. Advances in knowledge: It is possible to use conventional diagnostic X-ray equipment in applications that normally require microfocus X-ray sources. This presents some possibilities for clinical applications. PMID:24779409

  14. Application of dual-energy x-ray techniques for automated food container inspection

    NASA Astrophysics Data System (ADS)

    Shashishekhar, N.; Veselitza, D.

    2016-02-01

    Manufacturing for plastic food containers often results in small metal particles getting into the containers during the production process. Metal detectors are usually not sensitive enough to detect these metal particles (0.5 mm or lesser), especially when the containers are stacked in large sealed shipping packages; X-ray inspection of these packages provides a viable alternative. This paper presents the results of an investigation into dual-energy X-ray techniques for automated detection of small metal particles in plastic food container packages. The sample packages consist of sealed cardboard boxes containing stacks of food containers: plastic cups for food, and Styrofoam cups for noodles. The primary goal of the investigation was to automatically identify small metal particles down to 0.5 mm diameter in size or less, randomly located within the containers. The multiple container stacks in each box make it virtually impossible to reliably detect the particles with single-energy X-ray techniques either visually or with image processing. The stacks get overlaid in the X-ray image and create many indications almost identical in contrast and size to real metal particles. Dual-energy X-ray techniques were investigated and found to result in a clear separation of the metal particles from the food container stack-ups. Automated image analysis of the resulting images provides reliable detection of the small metal particles.

  15. Aggravation of Pre-Existing Atrioventricular Block, Wenckebach Type, Provoked by Application of X-Ray Contrast Medium

    SciTech Connect

    Brodmann, Marianne Seinost, Gerald; Stark, Gerhard; Pilger, Ernst

    2006-12-15

    Background. Significant bradycardia followed by cardiac arrest related to single bolus administration of X-ray contrast medium into a peripheral artery has not, to our knowledge, been described in the literature. Methods and Results. While performing a percutaneous transluminal angioplasty of the left superficial femoral artery in a 68-year old patient with a pre-existing atrioventricular (AV) block, Wenckebach type, he developed an AV block III after a single bolus injection of intra-arterial X-ray contrast medium. Conclusion. We believe that application of contrast medium causes a transitory ischemia in the obstructed vessel and therefore elevation of endogenous adenosine. In the case of a previously damaged AV node this elevation of endogenous adenosine may be responsible for the development of a short period of third-degree AV block.

  16. Absolute x-ray energy calibration over a wide energy range using a diffraction-based iterative method.

    PubMed

    Hong, Xinguo; Chen, Zhiqiang; Duffy, Thomas S

    2012-06-01

    In this paper, we report a method of precise and fast absolute x-ray energy calibration over a wide energy range using an iterative x-ray diffraction based method. Although accurate x-ray energy calibration is indispensable for x-ray energy-sensitive scattering and diffraction experiments, there is still a lack of effective methods to precisely calibrate energy over a wide range, especially when normal transmission monitoring is not an option and complicated micro-focusing optics are fixed in place. It is found that by using an iterative algorithm the x-ray energy is only tied to the relative offset of sample-to-detector distance, which can be readily varied with high precision of the order of 10(-5) -10(-6) spatial resolution using gauge blocks. Even starting with arbitrary initial values of 0.1 Å, 0.3 Å, and 0.4 Å, the iteration process converges to a value within 3.5 eV for 31.122 keV x-rays after three iterations. Different common diffraction standards CeO(2), Au, and Si show an energy deviation of 14 eV. As an application, the proposed method has been applied to determine the energy-sensitive first sharp diffraction peak of network forming GeO(2) glass at high pressure, exhibiting a distinct behavior in the pressure range of 2-4 GPa. Another application presented is pair distribution function measurement using calibrated high-energy x-rays at 82.273 keV. Unlike the traditional x-ray absorption-based calibration method, the proposed approach does not rely on any edges of specific elements, and is applicable to the hard x-ray region where no appropriate absorption edge is available.

  17. Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

    ERIC Educational Resources Information Center

    Ball, Stephen; Cowan, Celsi; Thyfault, John; LaFontaine, Tom

    2014-01-01

    Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18-65, completed a skinfold assessment and dual energy x-ray…

  18. Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

    ERIC Educational Resources Information Center

    Ball, Stephen; Cowan, Celsi; Thyfault, John; LaFontaine, Tom

    2014-01-01

    Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18-65, completed a skinfold assessment and dual energy x-ray…

  19. Development of a fast readout system for the detection of low energy X rays

    NASA Astrophysics Data System (ADS)

    Gryboś, P.; Bialas, W.; Cabal, A.; Dabrowski, W.; Giubellino, P.; Idzik, M.; Wheadon, R.; Montaño, L.; Szczygiel, R.

    2000-10-01

    In this paper we present the motivations and the status of the development of a low-energy X-ray detection system based on a silicon strip detector and an integrated multichannel readout. The system is optimized for the detection of X-rays in the 6 to 30 keV energy range at a rate up a few hundred of kilohertz per detection unit. These parameters are adequate for many crystallographic and some medical imaging applications, and the system allows simple, room-temperature operation.

  20. Performance of HEXTE engineering model phoswich detectors. [High Energy X-ray Timing Experiment

    NASA Technical Reports Server (NTRS)

    Hink, Paul; Pelling, Michael; Rothschild, Richard

    1992-01-01

    The preliminary design for the 15-250 keV, 200/sq cm, phoswich detectors for the High Energy X-ray Timing Experiment for NASA's X-ray Timing Explorer mission has been completed, and the first engineering model has been fabricated. This unit has undergone extensive environmental and performance testing, including extended vibration, thermal range, resolution, uniformity, and pulse shape, and is within specifications for all tests. Broad beam energy resolution of better than 15 percent at 60 keV and clear separation of NaI and CsI pulse shape peaks are seen. The design and test results will be presented.

  1. Material specific X-ray imaging using an energy-dispersive pixel detector

    NASA Astrophysics Data System (ADS)

    Egan, Christopher K.; Wilson, Matthew D.; Veale, Matthew C.; Seller, Paul; Jacques, Simon D. M.; Cernik, Robert J.

    2014-04-01

    By imaging the X-ray spectral properties or ‘colours’ we have shown how material specific imaging can be performed. Using a pixelated energy-dispersive X-ray detector we record the absorbed and emitted hard X-radiation and measure the energy (colour) and intensity of the photons. Using this technology, we are not only able to obtain attenuation contrast but also to image chemical (elemental) variations inside objects, potentially opening up a very wide range of applications from materials science to medical diagnostics.

  2. High energy X-ray observations of the 38-second pulsar

    NASA Technical Reports Server (NTRS)

    Byrne, P. F.; Levine, A. M.; Bautz, M.; Howe, S. K.; Lang, F. L.; Primini, F. A.; Lewin, W. H. G.; Gruber, D. E.; Knight, F. K.; Nolan, P. L.

    1981-01-01

    The results of observations of the 38-second pulsar obtained at high X-ray energies (13-180 keV) with the UCSD/MIT instrument aboard HEAO 1 are reported. The results include a measurement of the source location, measurement of the pulse profile, and determination of the average intensity and spectrum during each of three time intervals spanning a baseline of 1 year. The total intensity of the pulsar is seen to vary on a 6-month time scale. The spectrum is hard but, like other X-ray pulsars, steepens at energies above 20 keV.

  3. Place of HgI/sub 2/ energy-dispersive x-ray detectors

    SciTech Connect

    Dabrowski, A.J.; Huth, G.C.; Iwanczyk, J.S.; Kusmiss, J.H.; Barton, J.S.; Szymczyk, J.M.; Schnepple, W.F.; Lynn, R.

    1982-01-01

    After a review of solid-state conduction counters, in general, and of the history of mercuric iodide, in particular, the theory of operation of solid-state energy-dispersive HgI/sub 2/ detectors is dicusssed. The main factors which limit energy resolution in solid-state compound detectors are considered, including statistical fluctuations in charge generation, the window effect, trapping, inhomogeneities in the detector material, and electronic noise. Potential applications of room-temperature HgI/sub 2/ x-ray detectors are listed, and general considerations are discussed for x-ray fluorescence analysis with HgI/sub 2/. Directions of current investigations are given. (LEW)

  4. Catalytic Adventures in Space and Time Using High Energy X-rays

    SciTech Connect

    Newton, Mark A.; Di Michiel, Marco; Ferri, Davide; Fernàndez-Garcia, Marcos; Beale, Andrew M.; Jacques, Simon D. M.; Chupas, Peter J.; Chapman, Karena W.

    2014-09-16

    Very high energy X-rays have long offered great promise in providing great insight into the inner workings of catalysts; insights that may complement the array of techniques available to researchers in catalysis either in the laboratory or at more conventional X-ray wavelengths. This contribution aims to critically assess the diverse possibilities now available in the high energy domain as a result of the maturation of third generation synchrotron facilities and to look forward to the potential that forthcoming developments in synchrotron source technology may offer the world of catalysis in the near future.

  5. The chemical sensitivity of X-ray spectroscopy: high energy resolution XANES versus X-ray emission spectroscopy of substituted ferrocenes.

    PubMed

    Atkins, Andrew J; Bauer, Matthias; Jacob, Christoph R

    2013-06-07

    X-ray spectroscopy at the metal K-edge is an important tool for understanding catalytic processes and provides insight into the geometric and electronic structures of transition metal complexes. In particular, X-ray emission-based methods such as high-energy resolution fluorescence detection (HERFD), X-ray absorption near-edge spectroscopy (XANES) and valence-to-core X-ray emission spectroscopy (V2C-XES) hold the promise of providing increased chemical sensitivity compared to conventional X-ray absorption spectroscopy. Here, we explore the ability of HERFD-XANES and V2C-XES spectroscopy to distinguish substitutions beyond the directly coordinated atoms for the example of ferrocene and selected ferrocene derivatives. The experimental spectra are assigned and interpreted through the use of density functional theory (DFT) calculations. We find that while the pre-edge peaks in the HERFD-XANES spectra are affected by substituents at the cyclopentadienyl ring containing π-bonds [A. J. Atkins, Ch. R. Jacob and M. Bauer, Chem.-Eur. J., 2012, 18, 7021], the V2C-XES spectra are virtually unchanged. The pre-edge in HERFD-XANES probes the weak transition to unoccupied metal d-orbitals, while the V2C-XES spectra are determined by dipole-allowed transitions from occupied ligand orbitals to the 1s core hole. The latter turn out to be less sensitive to changes beyond the first coordination shell.

  6. Ice core stratigraphy using dual energy x-ray absorptiometry (DEXA)

    NASA Astrophysics Data System (ADS)

    Kroger, Chris; Thomson, Julian; Bertler, Nancy; Morgenstern, Uwe

    2006-05-01

    We are presenting a technique using x-rays to detect strata caused by density variation in 94 mm diameter ice cores. Moreover, high resolution density is determined. A 54 m long ice core retrieved from the Tasman Glacier of the Southern Alps in New Zealand has been x-ray scanned and the images were analysed. As a dual energy capable x-ray (DEXA) scanner was used, DEXA analysis techniques were used where appropriate, such as for the enhancement of strata visibility in the images. Density calculations though were based on a single energy model, using the fundamental law of x-ray attenuation. As the model does not precisely reflect realistic conditions, calibrations were made for the material properties and pixel scaling. Results of detected strata were compared to traditional visual light methods, where up to a depth of ~35 m better detail was achieved using x-rays. Density data was checked against the average volumetric density. Results compare well with the volumetric density, however a small bias exists, which at present requires further investigation.

  7. Talbot-Lau x-ray interferometry for high energy density plasma diagnostic

    SciTech Connect

    Stutman, D.; Finkenthal, M.

    2011-11-15

    High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer.

  8. Talbot-Lau x-ray interferometry for high energy density plasma diagnostic.

    PubMed

    Stutman, D; Finkenthal, M

    2011-11-01

    High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer. © 2011 American Institute of Physics

  9. Carbon nanotubes and fullerites in high-energy and X-ray physics

    NASA Astrophysics Data System (ADS)

    Artru, X.; Fomin, S. P.; Shul'ga, N. F.; Ispirian, K. A.; Zhevago, N. K.

    2005-06-01

    It is demonstrated that the unique structures of carbon nanotubes and single-crystals of C60 fullerenes may have applications to X-ray, neutron and high-energy particle physics, based on channeling, Bragg diffraction and coherent radiation. These are reviewed, pointing out the peculiarities and advantages of nanocrystals compared to ordinary crystals. New applications are explored: X-rays and neutron channeling, undulator radiation in periodically bent nanotubes, “channeled” transition radiation. Quantum and classical channeling, channeling in bent nanocrystals, Bragg scattering of X-rays and neutrons, channeling radiation, coherent bremsstrahlung, parametric X-ray and nanotube undulator radiation are particularly studied using both analytical and Monte-Carlo methods. Continuous potentials, electron densities, transverse energy levels, and spectra of various types of coherent radiation are calculated. Large dechanneling lengths of positive particles, bending efficiencies, reflecting coefficients of soft X-rays and PXR yields are predicted. Principles of particle detectors using photo- and secondary electron emissions are discussed.

  10. [Differential dose albedo for high-energy X-rays on concrete slab].

    PubMed

    Kato, Hideki

    2006-08-20

    We computed the differential dose albedo (alpha(D)) for high-energy X-rays on a concrete slab when the incident angle, reflection angle, and azimuth angle were changed, by means of Monte Carlo simulation. We found that alpha(D) changed with incident, reflection, and azimuth angles to the concrete slab. On the whole, the larger the incident angle, the larger alpha(D) tended to become. If the incident angle and reflection angle were the same, the larger the azimuth angle, the smaller alpha(D) tended to become. When the incident, reflection, and azimuth angles were the same, the smaller the X-ray energy was, the larger alpha(D) became, in the order of 10 MV, 6 MV, and 4 MV X-rays.

  11. Superconducting Detector System for High-Resolution Energy-Dispersive Soft X-Ray Spectroscopy

    SciTech Connect

    Friedrich, S; Niedermayr, T; Drury, O; Funk, T; Frank, M; Labov, S E; Cramer, S

    2001-02-21

    Synchrotron-based soft x-ray spectroscopy is often limited by detector performance. Grating spectrometers have the resolution, but lack the efficiency for the analysis of dilute samples. Semiconducting Si(Li) or Ge detectors are efficient, but often lack the resolution to separate weak signals from strong nearby lines in multi-element samples. Superconducting tunnel junctions (STJs) operated at temperatures below 1 K can be used as high-resolution high-efficiency x-ray detectors. They combine high energy resolution around 10 eV FWHM with the broad band efficiency of energy-dispersive detectors. We have designed a two-stage adiabatic demagnetization refrigerator (ADR) to operate STJ detectors in x-ray fluorescence measurements at beam line 4 of the ALS. We demonstrate the capabilities of such a detector system for fluorescence analysis of dilute metal sites in proteins and inorganic model compounds.

  12. High-energy synchrotron X-ray radiography of shock-compressed materials

    NASA Astrophysics Data System (ADS)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This presentation will discuss the development and application of a high-energy (50 to 250 keV) synchrotron X-ray imaging method to study shock-compressed, high-Z samples at Beamline I12 at the Diamond Light Source synchrotron (Rutherford-Appleton Laboratory, UK). Shock waves are driven into materials using a portable, single-stage gas gun designed by the Institute of Shock Physics. Following plate impact, material deformation is probed in-situ by white-beam X-ray radiography and complimentary velocimetry diagnostics. The high energies, large beam size (13 x 13 mm), and appreciable sample volumes (~ 1 cm3) viable for study at Beamline I12 compliment existing in-house pulsed X-ray capabilities and studies at the Dynamic Compression Sector. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  13. Influence of experimental conditions on atom column visibility in energy dispersive X-ray spectroscopy.

    PubMed

    Dycus, J H; Xu, W; Sang, X; D'Alfonso, A J; Chen, Z; Weyland, M; Allen, L J; Findlay, S D; LeBeau, J M

    2016-12-01

    Here we report the influence of key experimental parameters on atomically resolved energy dispersive X-ray spectroscopy (EDX). In particular, we examine the role of the probe forming convergence semi-angle, sample thickness, lattice spacing, and dwell/collection time. We show that an optimum specimen-dependent probe forming convergence angle exists to maximize the signal-to-noise ratio of the atomically resolved signal in EDX mapping. Furthermore, we highlight that it can be important to select an appropriate dwell time to efficiently process the X-ray signal. These practical considerations provide insight for experimental parameters in atomic resolution energy dispersive X-ray analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Low energy prepulse for 10 Hz operation of a soft-x-ray laser.

    PubMed

    Habib, J; Guilbaud, O; Zielbauer, B; Zimmer, D; Pittman, M; Kazamias, S; Montet, C; kuehl, T; Ros, D

    2012-04-23

    The influence on Nickel-like Molybdenum soft-x-ray laser performance and stability of a low energy laser prepulse arriving prior to the main laser pumping pulses is experimentally investigated. A promising regime for 10 Hz operation has been observed. A four times increase in soft-x-ray laser operation time with a same target surface is demonstrated. This soft-x-ray laser operation mode corresponds to an optimum delay between the prepulse and the main pulses and to a prepulse energy greater than 20 mJ. We also show that this regime is not associated with a weaker degradation of the target or any reduced ablation rate. Therefore the role of preplasma density gradient in this effect is discussed. © 2012 Optical Society of America

  15. Time-delayed beam splitting with energy separation of x-ray channels

    SciTech Connect

    Stetsko, Yuri P.; Shvyd'ko, Yuri V.; Brian Stephenson, G.

    2013-10-21

    We introduce a time-delayed beam splitting method based on the energy separation of x-ray photon beams. It is implemented and theoretically substantiated on an example of an x-ray optical scheme similar to that of the classical Michelson interferometer. The splitter/mixer uses Bragg-case diffraction from a thin diamond crystal. Another two diamond crystals are used as back-reflectors. Because of energy separation and a minimal number (three) of optical elements, the split-delay line has high efficiency and is simple to operate. Due to the high transparency of diamond crystal, the split-delay line can be used in a beam sharing mode at x-ray free-electron laser facilities.

  16. Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study

    NASA Astrophysics Data System (ADS)

    Cho, H.-M.; Ding, H.; Ziemer, BP; Molloi, S.

    2014-12-01

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3  ×  3 mm2 in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

  17. The application of thermoluminescence dosimetry in X-ray energy discrimination.

    PubMed

    Nelson, V K; Holloway, L; McLean, I D

    2015-12-01

    Clinical dosimetry requires an understanding of radiation energy to accurately determine the delivered dose. For many situations this is known, however there are also many situations where the radiation energy is not well known, thus limiting dosimetric accuracy. This is the case in personnel dosimetry where thermo luminescent (TL) dosimetry is the method of choice. Traditionally beam energy characteristics in personnel dosimetry are determined through discrimination with the use of various filters fitted within a radiation monitor. The presence of scattered and characteristic radiation produced by these metallic filters, however, can compromise the results. In this study the TL response of five materials TLD100, TLD100H, TLD200, TLD400 and TLD500, was measured at various X-ray energies. The TL sensitivity ratio for various combinations of materials as a function of X-ray energy was calculated. The results indicate that in personal dosimetry a combination of three or more TL detector system has a better accuracy of estimation of effective radiation energy of an X-ray beam than some of the current method of employed for energy estimation and has the potential to improve the accuracy in dose determination in a variety of practical situations. The development of this method also has application in other fields including quality assurance of the orthovoltage therapy machines, dosimetry intercomparisons of kilovoltage X-ray beams, and measurement of the dose to critical organs outside a treatment field of a megavoltage therapy beam.

  18. A new approach to account for the medium-dependent effect in model-based dose calculations for kilovoltage x-rays.

    PubMed

    Pawlowski, Jason M; Ding, George X

    2011-07-07

    This study presents a new approach to accurately account for the medium-dependent effect in model-based dose calculations for kilovoltage (kV) x-rays. This approach is based on the hypothesis that the correction factors needed to convert dose from model-based dose calculations to absorbed dose-to-medium depend on both the attenuation characteristics of the absorbing media and the changes to the energy spectrum of the incident x-rays as they traverse media with an effective atomic number different than that of water. Using Monte Carlo simulation techniques, we obtained empirical medium-dependent correction factors that take both effects into account. We found that the correction factors can be expressed as a function of a single quantity, called the effective bone depth, which is a measure of the amount of bone that an x-ray beam must penetrate to reach a voxel. Since the effective bone depth can be calculated from volumetric patient CT images, the medium-dependent correction factors can be obtained for model-based dose calculations based on patient CT images. We tested the accuracy of this new approach on 14 patients for the case of calculating imaging dose from kilovoltage cone-beam computed tomography used for patient setup in radiotherapy, and compared it with the Monte Carlo method, which is regarded as the 'gold standard'. For all patients studied, the new approach resulted in mean dose errors of less than 3%. This is in contrast to current available inhomogeneity corrected methods, which have been shown to result in mean errors of up to -103% for bone and 8% for soft tissue. Since there is a huge gain in the calculation speed relative to the Monte Carlo method (∼two orders of magnitude) with an acceptable loss of accuracy, this approach provides an alternative accurate dose calculation method for kV x-rays.

  19. A new approach to account for the medium-dependent effect in model-based dose calculations for kilovoltage x-rays

    NASA Astrophysics Data System (ADS)

    Pawlowski, Jason M.; Ding, George X.

    2011-07-01

    This study presents a new approach to accurately account for the medium-dependent effect in model-based dose calculations for kilovoltage (kV) x-rays. This approach is based on the hypothesis that the correction factors needed to convert dose from model-based dose calculations to absorbed dose-to-medium depend on both the attenuation characteristics of the absorbing media and the changes to the energy spectrum of the incident x-rays as they traverse media with an effective atomic number different than that of water. Using Monte Carlo simulation techniques, we obtained empirical medium-dependent correction factors that take both effects into account. We found that the correction factors can be expressed as a function of a single quantity, called the effective bone depth, which is a measure of the amount of bone that an x-ray beam must penetrate to reach a voxel. Since the effective bone depth can be calculated from volumetric patient CT images, the medium-dependent correction factors can be obtained for model-based dose calculations based on patient CT images. We tested the accuracy of this new approach on 14 patients for the case of calculating imaging dose from kilovoltage cone-beam computed tomography used for patient setup in radiotherapy, and compared it with the Monte Carlo method, which is regarded as the 'gold standard'. For all patients studied, the new approach resulted in mean dose errors of less than 3%. This is in contrast to current available inhomogeneity corrected methods, which have been shown to result in mean errors of up to -103% for bone and 8% for soft tissue. Since there is a huge gain in the calculation speed relative to the Monte Carlo method (~two orders of magnitude) with an acceptable loss of accuracy, this approach provides an alternative accurate dose calculation method for kV x-rays.

  20. Energy dispersive X-ray diffraction in the diamond anvil, high-pressure apparatus - Comparison of synchrotron and conventional X-ray sources

    NASA Technical Reports Server (NTRS)

    Spain, I. L.; Black, D. R.

    1985-01-01

    The use of both conventional fixed-anode X-ray sources and synchrotron radiation to carry out energy-dispersive X-ray diffraction experiments at high pressure in a diamond anvil cell, is discussed. The photon flux at the sample and at the detector for the two cases are compared and the results are presented in graphs. It is shown that synchrotron radiation experiments can be performed with nearly two orders of magnitude increase in data rate if superior detectors and detector electronics are available.

  1. Energy dispersive X-ray diffraction in the diamond anvil, high-pressure apparatus - Comparison of synchrotron and conventional X-ray sources

    NASA Technical Reports Server (NTRS)

    Spain, I. L.; Black, D. R.

    1985-01-01

    The use of both conventional fixed-anode X-ray sources and synchrotron radiation to carry out energy-dispersive X-ray diffraction experiments at high pressure in a diamond anvil cell, is discussed. The photon flux at the sample and at the detector for the two cases are compared and the results are presented in graphs. It is shown that synchrotron radiation experiments can be performed with nearly two orders of magnitude increase in data rate if superior detectors and detector electronics are available.

  2. Design of a medium size x-ray mirror module based on thin glass foils

    NASA Astrophysics Data System (ADS)

    Basso, Stefano; Civitani, Marta; Pareschi, Giovanni

    2016-07-01

    The hot slumping glass technology for X-ray mirror is under development and in the last years the results have been improved. Nustar is the first X-ray telescope based on slumped glass foils and it benefit is the low cost compared to the direct polishing of glass. With the slumping technique it is possible to maintain the glass mass to low values with respect to the direct polishing, but in general the angular resolution is worst. A further technique based on glass is the cold shaping of foils. The improved capabilities of manufacturing thin glass foils, pushed by the industrial application for screens, open new possibilities for X-ray mirror. The increase in strength of thin tempered glasses, the reduction of thickness errors and the good roughness of flat foils are potentially great advantages. In this paper a design of a mediumsize X-ray mirror module is analysed. It is based on integration of glass foils, stacked directly on a supporting structure that is part of the X-ray telescope using stiffening ribs as spacer between foils. The alignment of each stack is performed directly into the integration machine avoiding the necessity of the alignment of different stacked modules. A typical module (glass optic and metallic structure) provides an effective area of 10 cm2/kg at 1 keV (with a mass of about 50- 100 kg and a focal length of 10 m).

  3. Investigation of Fatigue Crack Initiation from a Non Metallic Inclusion via High Energy X Ray Diffraction Microscopy (Postprint)

    DTIC Science & Technology

    2017-07-14

    AFRL-RX-WP-JA-2017-0320 INVESTIGATION OF FATIGUE CRACK INITIATION FROM A NON-METALLIC INCLUSION VIA HIGH ENERGY X-RAY DIFFRACTION...CRACK INITIATION FROM A NON-METALLIC INCLUSION VIA HIGH ENERGY X-RAY DIFFRACTION MICROSCOPY (POSTPRINT) 5a. CONTRACT NUMBER IN-HOUSE 5b...microstructure, leading to crack nucleation. In this study, fully 3-D characterization methods using high energy synchrotron x-rays are combined with in

  4. A Rotational and Axial Motion System Load Frame Insert for In Situ High Energy X-Ray Studies (Postprint)

    DTIC Science & Technology

    2015-09-08

    AFRL-RX-WP-JA-2016-0273 A ROTATIONAL AND AXIAL MOTION SYSTEM LOAD FRAME INSERT FOR IN SITU HIGH ENERGY X - RAY STUDIES (POSTPRINT...SUBTITLE A ROTATIONAL AND AXIAL MOTION SYSTEM LOAD FRAME INSERT FOR IN SITU HIGH ENERGY X - RAY STUDIES (POSTPRINT) 5a. CONTRACT NUMBER FA8650-14...final publication is available at http://dx.doi.org/10.1063/1.4927855 14. ABSTRACT (Maximum 200 words) High energy x - ray characterization methods hold

  5. A dynamic material discrimination algorithm for dual MV energy X-ray digital radiography.

    PubMed

    Li, Liang; Li, Ruizhe; Zhang, Siyuan; Zhao, Tiao; Chen, Zhiqiang

    2016-08-01

    Dual-energy X-ray radiography has become a well-established technique in medical, industrial, and security applications, because of its material or tissue discrimination capability. The main difficulty of this technique is dealing with the materials overlapping problem. When there are two or more materials along the X-ray beam path, its material discrimination performance will be affected. In order to solve this problem, a new dynamic material discrimination algorithm is proposed for dual-energy X-ray digital radiography, which can also be extended to multi-energy X-ray situations. The algorithm has three steps: α-curve-based pre-classification, decomposition of overlapped materials, and the final material recognition. The key of the algorithm is to establish a dual-energy radiograph database of both pure basis materials and pair combinations of them. After the pre-classification results, original dual-energy projections of overlapped materials can be dynamically decomposed into two sets of dual-energy radiographs of each pure material by the algorithm. Thus, more accurate discrimination results can be provided even with the existence of the overlapping problem. Both numerical and experimental results that prove the validity and effectiveness of the algorithm are presented.

  6. Energy calibration of superconducting transition edge sensors for x-ray detection using pulse analysis

    SciTech Connect

    Hollerith, C.; Simmnacher, B.; Weiland, R.; Feilitzsch, F. v.; Isaila, C.; Jochum, J.; Potzel, W.; Hoehne, J.; Phelan, K.; Wernicke, D.; May, T.

    2006-05-15

    Transition edge sensors (TESs) have been developed to be used as high-resolution x-ray detectors. They show excellent energy resolution and can be used in many applications. TESs are a special kind of calorimeters that can determine small temperature changes after x-ray absorption. Such a temperature change causes a strong resistance change (superconducting to normal-conducting phase transition) that can be measured. The energy calibration of a TES based spectrometer is problematic due to the nonlinear behavior of the detector response. In this article, a method is introduced to calibrate the energy scale of TES spectra. This is accomplished by calculating the energy dependence of the response of the detector operated in electrothermal feedback mode. Using this method a calibration accuracy of a few eV for an x-ray energy of 6 keV can be achieved. Examples of energy dispersive x-ray spectroscopy (EDS) measurements demonstrate the high quality of this method for everyday use of TES EDS detectors in material analysis. However, because the method relies only on a few very general assumptions, it should also be useful for other kinds of TES detectors.

  7. COnstrain Dark Energy with X-ray (CODEX) clusters

    NASA Astrophysics Data System (ADS)

    Finoguenov, Alexis; SDSS Team; Cfht Team; Carma Team

    2012-09-01

    We describe the construction and follow-up observations of the most massive clusters in the Universe, selected in the SDSS-III survey using RASS data down to an unprecedented flux limit of -13 dex. In application to the cosmology studies, we demonstrate that we will achieve a 3% constraint on the dark energy equation of state, and in a combination with BOSS BAO measurement reach a FoM of 160.

  8. Bismuth sulfide nanoflowers for detection of X-rays in the mammographic energy range.

    PubMed

    Nambiar, Shruti; Osei, Ernest K; Yeow, John T W

    2015-03-24

    The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale "flower-like" structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials - 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber.

  9. Mass and Energy of Erupting Solar Plasma Observed with the X-Ray Telescope on Hinode

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Yi; Raymond, John C.; Reeves, Katharine K.; Moon, Yong-Jae; Kim, Kap-Sung

    2015-01-01

    We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light coronal mass ejection features are visible in some events. Five events are observed in several passbands in X-rays, which allows for the determination of the eruptive plasma temperature using a filter ratio method. We find that the isothermal temperatures vary from 1.6 to 10 MK. These temperatures are an average weighted toward higher temperature plasma. We determine the mass constraints of eruptive plasmas by assuming simplified geometrical structures of the plasma with isothermal plasma temperatures. This method provides an upper limit to the masses of the observed eruptive plasmas in X-ray passbands since any clumping causes the overestimation of the mass. For the other two events, we assume the temperatures are at the maximum temperature of the X-ray Telescope (XRT) temperature response function, which gives a lower limit of the masses. We find that the masses in XRT, ~3 × 1013-5 × 1014 g, are smaller in their upper limit than the total masses obtained by LASCO, ~1 × 1015 g. In addition, we estimate the radiative loss, thermal conduction, thermal, and kinetic energies of the eruptive plasma in X-rays. For four events, we find that the thermal conduction timescales are much shorter than the duration of eruption. This result implies that additional heating during the eruption may be required to explain the plasma observations in X-rays for the four events.

  10. Bismuth Sulfide Nanoflowers for Detection of X-rays in the Mammographic Energy Range

    PubMed Central

    Nambiar, Shruti; Osei, Ernest K.; Yeow, John T. W.

    2015-01-01

    The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale “flower-like” structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials – 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber. PMID:25801531

  11. Study on Dual-Energy X-ray Computed Tomography using Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Tsunoo, T.; Torikoshi, M.; Endo, M.; Natsuhori, M.; Kakizaki, T.; Yamada, N.; Itoh, N.; Uesugi, K.; Yagi, N.

    2004-05-01

    The electron density is one of the most important elements for the treatment planning in the radiotherapy, because this information is used for the range estimation of the heavy-ion beam. In order to measure more precise electron density, we have developed the dual-energy x-ray CT system using synchrotron radiation. The x-ray detector consists of 256 × 96 scintillator-array. It can take more than a hundred projection images per second. The response of the detector to x-rays was proved to be linear up to at least 1013 photon/pixel. The experiments were carried out using two monochromatic x-rays of 40 keV and 70 keV at the beam-line BL20B2 of SPring-8. As the results from samples of water, ethanol and solutions of dipotassium hydrogenphosphate with five concentrations, the electron densities measured in the dual-energy x-ray CT method were in agreement with the theoretical values by about ± 1%. This is almost the same level as that achieved by the one-dimensional CT system we developed previously. In addition, a sample of kidney of a pig fixed by formalin neutral buffer solution was used to distinguish the tissues in the CT images based on the electron density and the effective atomic number that was additionally obtained in the dual-energy x-ray CT. It suggested that renal pelvis was enriched with adipose tissue, and it was difficult to distinguish renal cortex and renal medulla.

  12. Study on Dual-Energy X-ray Computed Tomography using Synchrotron Radiation

    SciTech Connect

    Tsunoo, T.; Torikoshi, M.; Endo, M.; Natsuhori, M.; Kakizaki, T.; Yamada, N.; Itoh, N.; Uesugi, K.; Yagi, N.

    2004-05-12

    The electron density is one of the most important elements for the treatment planning in the radiotherapy, because this information is used for the range estimation of the heavy-ion beam. In order to measure more precise electron density, we have developed the dual-energy x-ray CT system using synchrotron radiation. The x-ray detector consists of 256 x 96 scintillator-array. It can take more than a hundred projection images per second. The response of the detector to x-rays was proved to be linear up to at least 1013 photon/pixel. The experiments were carried out using two monochromatic x-rays of 40 keV and 70 keV at the beam-line BL20B2 of SPring-8. As the results from samples of water, ethanol and solutions of dipotassium hydrogenphosphate with five concentrations, the electron densities measured in the dual-energy x-ray CT method were in agreement with the theoretical values by about {+-} 1%. This is almost the same level as that achieved by the one-dimensional CT system we developed previously. In addition, a sample of kidney of a pig fixed by formalin neutral buffer solution was used to distinguish the tissues in the CT images based on the electron density and the effective atomic number that was additionally obtained in the dual-energy x-ray CT. It suggested that renal pelvis was enriched with adipose tissue, and it was difficult to distinguish renal cortex and renal medulla.

  13. The detection of X-rays from the hot interstellar medium of the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Wang, Q.; Hamilton, T.; Helfand, D. J.; Wu, X.

    1991-01-01

    A comprehensive reanalysis is presented of the Einstein IPC data base on the LMC, and a number of new algorithms are used to improve the reliability of the point source detection in this crowded region and to produce the first large-scale map of diffuse emission free from the effects of solar scattered X-rays and cosmic-ray particles. Algorithms described in detail include a technique to decontaminate fields containing solar scattered flux, a mechanism for obtaining a spectrum-weighted vignetting function, and a source excision and smoothing algorithm which results in a diffuse map of uniform statistical quality. A catalog of discrete X-rays sources in the direction of the LMC is presented which contains 33 new sources and eliminates a number of spurious and/or marginal directions from previous lists. A possible detection of the long-sought shadowing effect on the cosmic X-ray background produced by cold LMC gas is reported.

  14. Thermal Acoustic Sensor for High Pulse Energy X-ray FEL Beams

    SciTech Connect

    Smith, T.J.; Frisch, J.C.; Kraft, E.M.; Loos, J.; Bentsen, G.S.; /Rochester U.

    2011-12-13

    The pulse energy density of X-ray FELs will saturate or destroy conventional X-ray diagnostics, and the use of large beam attenuation will result in a beam that is dominated by harmonics. We present preliminary results at the LCLS from a pulse energy detector based on the thermal acoustic effect. In this type of detector an X-ray resistant material (boron carbide in this system) intercepts the beam. The pulse heating of the target material produces an acoustic pulse that can be detected with high frequency microphones to produce a signal that is linear in the absorbed energy. The thermal acoustic detector is designed to provide first- and second-order calorimetric measurement of X-ray FEL pulse energy. The first-order calorimetry is a direct temperature measurement of a target designed to absorb all or most of the FEL pulse power with minimal heat leak. The second-order measurement detects the vibration caused by the rapid thermoelastic expansion of the target material each time it absorbs a photon pulse. Both the temperature change and the amplitude of the acoustic signal are directly related to the photon pulse energy.

  15. Energy-discriminating X-ray computed tomography system utilizing a cadmium telluride detector

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Abderyim, Purkhet; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Takahasi, Kiyomi; Sato, Shigehiro; Ogawae, Akira; Onagawa, Jun

    2010-07-01

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type with a cadmium telluride (CdTe) detector, and a projection curve is obtained by translation scanning using the CdTe detector in conjunction with an x-stage. An object is rotated by the rotation step angle using a turntable between the translation scans. Thus, CT is carried out by repeating the translation scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selecting photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  16. CZT detector for dual-energy x-ray absorptiometry (DEXA)

    NASA Astrophysics Data System (ADS)

    Wear, James; Buchholz, Michael; Payne, Randall K.; Gorsuch, Darrell; Bisek, Joseph; Ergun, David L.; Grosholz, Joe; Falk, Ron

    2000-12-01

    A cadmium-zinc-telluride (CZT) detector has been developed for a bone densitometer that uses dual-energy x-ray absorptiometry (DEXA) to determine bone mineral density in vivo. A linear array of 16 discrete CZT detectors is used with a narrow fan-shaped x-ray beam to scan the patient. Each detector is 3 mm thick and 7 mm by 3 mm in area and has simple planar contacts. The x-ray beam has two broad energy lobes with effective energies of approximately 38 keV and approximately 65 keV. The energy sensitivity of the CZT detectors allows discrimination between low and high energy x-rays. Using DEXA, the relative difference in these two count rates permits a quantitative measurement of the real densities of bone mineral and soft tissue. The detectors demonstrate good performance characteristics and stable operation in a clinical environment. This paper discusses the suitability of CZT for use in DEXA applications and describes its successful implementation and performance in this bone densitometer.

  17. CMOS-sensors for energy-resolved X-ray imaging

    NASA Astrophysics Data System (ADS)

    Doering, D.; Amar-Youcef, S.; Baudot, J.; Deveaux, M.; Dulinski, W.; Kachel, M.; Linnik, B.; Müntz, C.; Stroth, Joachim

    2016-01-01

    Due to their low noise, CMOS Monolithic Active Pixel Sensors are suited to sense X-rays with a few keV quantum energy, which is of interest for high resolution X-ray imaging. Moreover, the good energy resolution of the silicon sensors might be used to measure this quantum energy. Combining both features with the good spatial resolution of CMOS sensors opens the potential to build ``color sensitive" X-ray cameras. Taking such colored images is hampered by the need to operate the CMOS sensors in a single photon counting mode, which restricts the photon flux capability of the sensors. More importantly, the charge sharing between the pixels smears the potentially good energy resolution of the sensors. Based on our experience with CMOS sensors for charged particle tracking, we studied techniques to overcome the latter by means of an offline processing of the data obtained from a CMOS sensor prototype. We found that the energy resolution of the pixels can be recovered at the expense of reduced quantum efficiency. We will introduce the results of our study and discuss the feasibility of taking colored X-ray pictures with CMOS sensors.

  18. Preliminary research on dual-energy X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Han, Hua-Jie; Wang, Sheng-Hao; Gao, Kun; Wang, Zhi-Li; Zhang, Can; Yang, Meng; Zhang, Kai; Zhu, Pei-Ping

    2016-04-01

    Dual-energy X-ray absorptiometry (DEXA) has been widely applied to measure the bone mineral density (BMD) and soft-tissue composition of the human body. However, the use of DEXA is greatly limited for low-Z materials such as soft tissues due to their weak absorption, while X-ray phase-contrast imaging (XPCI) shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. In this paper, we propose a novel X-ray phase-contrast method to measure the area density of low-Z materials, including a single-energy method and a dual-energy method. The single-energy method is for the area density calculation of one low-Z material, while the dual-energy method aims to calculate the area densities of two low-Z materials simultaneously. Comparing the experimental and simulation results with the theoretical ones, the new method proves to have the potential to replace DEXA in area density measurement. The new method sets the prerequisites for a future precise and low-dose area density calculation method for low-Z materials. Supported by Major State Basic Research Development Program (2012CB825800), Science Fund for Creative Research Groups (11321503) and National Natural Science Foundation of China (11179004, 10979055, 11205189, 11205157)

  19. Monochromatic x-ray radiography for areal-density measurement of inertial fusion energy fuel in fast ignition experiment

    SciTech Connect

    Fujioka, Shinsuke; Fujiwara, Takashi; Tanabe, Minoru; Nishimura, Hiroaki; Nagatomo, Hideo; Ohira, Shinji; Shiraga, Hiroyuki; Azechi, Hiroshi; Inubushi, Yuichi

    2010-10-15

    Ultrafast, two-dimensional x-ray imaging is an important diagnostics for the inertial fusion energy research, especially in investigating implosion dynamics at the final stage of the fuel compression. Although x-ray radiography was applied to observing the implosion dynamics, intense x-rays emitted from the high temperature and dense fuel core itself are often superimposed on the radiograph. This problem can be solved by coupling the x-ray radiography with monochromatic x-ray imaging technique. In the experiment, 2.8 or 5.2 keV backlight x-rays emitted from laser-irradiated polyvinyl chloride or vanadium foils were selectively imaged by spherically bent quartz crystals with discriminating the out-of-band emission from the fuel core. This x-ray radiography system achieved 24 {mu}m and 100 ps of spatial and temporal resolutions, respectively.

  20. Monochromatic x-ray radiography for areal-density measurement of inertial fusion energy fuel in fast ignition experiment.

    PubMed

    Fujioka, Shinsuke; Fujiwara, Takashi; Tanabe, Minoru; Nishimura, Hiroaki; Nagatomo, Hideo; Ohira, Shinji; Inubushi, Yuichi; Shiraga, Hiroyuki; Azechi, Hiroshi

    2010-10-01

    Ultrafast, two-dimensional x-ray imaging is an important diagnostics for the inertial fusion energy research, especially in investigating implosion dynamics at the final stage of the fuel compression. Although x-ray radiography was applied to observing the implosion dynamics, intense x-rays emitted from the high temperature and dense fuel core itself are often superimposed on the radiograph. This problem can be solved by coupling the x-ray radiography with monochromatic x-ray imaging technique. In the experiment, 2.8 or 5.2 keV backlight x-rays emitted from laser-irradiated polyvinyl chloride or vanadium foils were selectively imaged by spherically bent quartz crystals with discriminating the out-of-band emission from the fuel core. This x-ray radiography system achieved 24 μm and 100 ps of spatial and temporal resolutions, respectively.

  1. Breast tissue contrast-simulating materials using energy-dispersive X-ray diffraction.

    PubMed

    Alkhateeb, Shyma M; Abdelkader, Mohamed H; Bradley, David A; Pani, Silvia

    2012-07-01

    Breast lesions and normal tissues have different molecular arrangements that affect their diffraction patterns. Different mouldable and non-mouldable materials were analysed using an energy dispersive X-ray diffraction system based on a conventional X-ray source (operated at 70 kVp) and a CdTe detector (Amptek XT-100), including a conventional spectroscopic chain. Combinations of materials were identified to have a contrast comparable to that achieved in diffraction imaging for different breast tissues at the momentum transfer values carrying the greatest amount of information (1.1 nm(-1) and 1.6 nm(-1)).

  2. Energy-resolving superconducting x-ray detectors with charge amplification due to multiple quasiparticle tunneling

    SciTech Connect

    Mears, C.A.; Labov, S.E. ); Barfknecht, A.T. )

    1993-11-22

    Superconducting tunnel junctions coupled to superconducting absorbers may be used as high-resolution, high-efficiency x-ray spectrometers. We have tested devices with niobium x-ray absorbing layers coupled to aluminum layers that serve as quasiparticle traps. The energy resolution at 6 keV was 49 eV full width at half-maximum. We estimate that each quasiparticle tunnels an average of 19 times before recombining, increasing the total charge transferred and therefore decreasing the effects of electronic noise.

  3. ICF ignition capsule neutron, gamma ray, and high energy x-ray images

    NASA Astrophysics Data System (ADS)

    Bradley, P. A.; Wilson, D. C.; Swenson, F. J.; Morgan, G. L.

    2003-03-01

    Post-processed total neutron, RIF neutron, gamma-ray, and x-ray images from 2D LASNEX calculations of burning ignition capsules are presented. The capsules have yields ranging from tens of kilojoules (failures) to over 16 MJ (ignition), and their implosion symmetry ranges from prolate (flattest at the hohlraum equator) to oblate (flattest towards the laser entrance hole). The simulated total neutron images emphasize regions of high DT density and temperature; the reaction-in-flight neutrons emphasize regions of high DT density; the gamma rays emphasize regions of high shell density; and the high energy x rays (>10 keV) emphasize regions of high temperature.

  4. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy.

    PubMed

    Chen, Z; D'Alfonso, A J; Weyland, M; Taplin, D J; Allen, L J; Findlay, S D

    2015-10-01

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Low energy x-ray response of Ge detectors with amorphous Ge entrance contacts

    SciTech Connect

    Luke, P.N.; Rossington, C.S.; Wesela, M.F.

    1993-10-01

    The low energy x-ray response of GI detectors with amorphous GI entrance contacts has been evaluated. The spectral background due to near contact incomplete charge collection was found to consist of two components: a low level component which is insensitive to applied voltage and a high level step-like component which is voltage dependent. At high operating voltages, the high level component can be completely suppressed, resulting in background levels which are much lower than those previously observed using GI detectors with Pd surface barrier or B ion implanted contacts, and which also compare favorably to those obtained with Si(Li) x-ray detectors. The response of these detectors to {sup 55}Fe and 1.77 keV x-rays is shown. A qualitative explanation of the origins of the observed background components is presented.

  6. Improvements in the Low Energy Collection Efficiency of Si(Li) X-ray Detectors

    SciTech Connect

    Cox,C.; Fischer, D.; Schwartz, W.; Song, Y.

    2005-01-01

    Soft X-ray beam-line applications are of fundamental importance to material research, and commonly employ high-resolution Si(Li) detectors for energy dispersive spectroscopy. However, the measurement of X-rays below 1 keV is compromised by absorption in the material layers in front of the active crystal and a dead layer at the crystal surface. Various Schottky barrier type contacts were investigated resulting in a 40% reduction of the dead-layer thickness and a factor of two increased sensitivity at carbon K{sub {alpha}} compared to the standard Si(Li) detector. Si(Li) detectors were tested on the U7A soft X-ray beam-line at the National Synchrotron Light Source and on a scanning electron microscope (SEM).

  7. New filtered-XRD low-energy X-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Tirsell, G.

    1982-05-01

    The filtered X-ray diode technique used to measure absolute soft X-ray spectra at the LLNL laser irradiation facilities was reviewed. The new, improved 10 channel system, designated the H, which was installed on the Shiva target chamber and used for several target irradiation series to measure time dependent spectra in the 0.2 to 1.5 keV range is described. The dependence of sensitivity on X-ray energy is shown for each of the channels used in these measurements. Alternative channels that can be set up including an array suitable for use below 500 eV and new fluor-MCP channels for broad coverage in the .15 to 5 keV range are outlined. The addition of mirror cutoff for improved channel resolution and the time responses of the various detector cable oscilloscope systems that were employed at Shiva laser facilities are reviewed.

  8. High Energy X-Ray Source Generation by Short Pulse High Intensity Lasers

    SciTech Connect

    Park, H-S; Koch, J A; Landen, O L; Phillips, T W; Goldsack, T; Clark, E; Eagleton, R; Edwards, R

    2003-09-02

    We are studying the feasibility of utilizing K{alpha} x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K{alpha} sources are created by relativistic electron plasma interactions in the target material after a radiation by short pulse high intensity lasers. In order to understand K{alpha} source characteristics such as production efficiency and brightness as a function of laser parameters, we have performed experiments using the 10 J, 100 fs JanUSP laser. We utilized single-photon counting spectroscopy and x-ray imaging diagnostics to characterize the K{alpha} source. We find that the K{alpha} conversion efficiency from the laser energy at 22 keV is {approx} 3 x 10{sup -4}.

  9. Femtosecond laser-generated high-energy-density states studied by x-ray FELs

    NASA Astrophysics Data System (ADS)

    Nakatsutsumi, M.; Appel, K.; Baehtz, C.; Chen, B.; Cowan, T. E.; Göde, S.; Konopkova, Z.; Pelka, A.; Priebe, G.; Schmidt, A.; Sukharnikov, K.; Thorpe, I.; Tschentscher, Th; Zastrau, U.

    2017-01-01

    The combination of powerful optical lasers and an x-ray free-electron laser (XFEL) provides unique capabilities to study the transient behaviour of matter in extreme conditions. The high energy density science instrument (HED instrument) at the European XFEL will provide the experimental platform on which an unique x-ray source can be combined with various types of high-power optical lasers. In this paper, we highlight selected scientific examples together with the associated x-ray techniques, with particular emphasis on femtosecond (fs)-timescale pump-probe experiments. Subsequently, we present the current design status of the HED instrument, outlining how the experiments could be performed. First user experiments will start at the beginning of 2018, after which various optical lasers will be commissioned and made available to the international scientific community.

  10. Demonstration of x-ray fluorescence imaging of a high-energy-density plasma.

    PubMed

    MacDonald, M J; Keiter, P A; Montgomery, D S; Biener, M M; Fein, J R; Fournier, K B; Gamboa, E J; Klein, S R; Kuranz, C C; LeFevre, H J; Manuel, M J-E; Streit, J; Wan, W C; Drake, R P

    2014-11-01

    Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.

  11. Demonstration of x-ray fluorescence imaging of a high-energy-density plasma

    SciTech Connect

    MacDonald, M. J. Gamboa, E. J.; Keiter, P. A.; Fein, J. R.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J.-E.; Wan, W. C.; Drake, R. P.; Montgomery, D. S.; Biener, M. M.; Fournier, K. B.; Streit, J.

    2014-11-15

    Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.

  12. Comparative study of ion, x-ray and neutron emission in a low energy plasma focus

    NASA Astrophysics Data System (ADS)

    Zakaullah, M.; Akhtar, Ijaz; Waheed, A.; Alamgir, Khalid; Shah, Anwar Z.; Murtaza, G.

    1998-05-01

    In a low energy (2.3 kJ) Mather-type deuterium plasma focus, neutron and x-ray emission is investigated by time integrated and time resolved detectors. CR-39 nuclear track ion detectors are employed for measuring charged particle angular distribution. Correlation of charged particles with neutron and x-ray emission is also investigated. The neutron emission profile is found to be composed of two pulses, the intensity and anisotropy of which vary with the filling pressure. The charged particle flux is maximum with high fluence anisotropy for the pressure range 2.5-3.0 mbar which is also the optimum pressure for high neutron emission with low fluence anisotropy 0963-0252/7/2/015/img9. The high neutron emission with low fluence anisotropy is attributed to the presence of trapped deuterons in an anomalous magnetic field. The relevant pressure range generates favourable conditions for plasma density and pinch filament diameter. X-ray emission is generally high at low pressure. For the pressure range of 2.5-4.0 mbar, the axial neutron detector registers a hard x-ray pulse, which may escape through a half inch thick Cu flange. These results suggest that at low pressures, the collapsing current sheath interacts with the anode end and causes intense low energy 0963-0252/7/2/015/img10 x-ray emission, but the neutron emission remains low. X-rays are dominantly Cu 0963-0252/7/2/015/img11. In the narrow pressure regime 2.5-3.0 mbar, the current sheath forms a pinch filament leading to high neutron yield with low fluence anisotropy.

  13. Modelling the effect of absorption from the interstellar medium on transient black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Eckersall, A. J.; Vaughan, S.; Wynn, G. A.

    2017-10-01

    All observations of Galactic X-ray binaries are affected by absorption from gas and dust in the interstellar medium (ISM) which imprints narrow (line) and broad (photoelectric edges) features on the continuum emission spectrum of the binary. Any spectral model used to fit data from a Galactic X-ray binary must therefore take account of these features; when the absorption is strong (as for most Galactic sources) it becomes important to accurately model the ISM absorption in order to obtain unbiased estimates of the parameters of the (emission) spectrum of the binary system. In this paper, we present analysis of some of the best spectroscopic data from the XMM-Newton RGS instrument using the most up-to-date photoabsorption model of the gaseous ISM ISMabs. We calculate column densities for H, O, Ne and Fe for seven transient black hole X-ray binary systems. We find that the hydrogen column densities in particular can vary greatly from those presented elsewhere in the literature. We assess the impact of using inaccurate column densities and older X-ray absorption models on spectral analysis using simulated data. We find that poor treatment of absorption can lead to large biases in inferred disc properties and that an independent analysis of absorption parameters can be used to alleviate such issues.

  14. Analysis of tincal ore waste by energy dispersive X-ray fluorescence (EDXRF) Technique

    NASA Astrophysics Data System (ADS)

    Kalfa, Orhan Murat; Üstündağ, Zafer; Özkırım, Ilknur; Kagan Kadıoğlu, Yusuf

    2007-01-01

    Etibank Borax Plant is located in Kırka-Eskişehir, Turkey. The borax waste from this plant was analyzed by means of energy dispersive X-ray fluorescence (EDXRF). The standard addition method was used for the determination of the concentration of Al, Fe, Zn, Sn, and Ba. The results are presented and discussed in this paper.

  15. Energy-Dispersive X-Ray Fluorescence Spectrometry: A Long Overdue Addition to the Chemistry Curriculum

    ERIC Educational Resources Information Center

    Palmer, Peter T.

    2011-01-01

    Portable Energy-Dispersive X-Ray Fluorescence (XRF) analyzers have undergone significant improvements over the past decade. Salient advantages of XRF for elemental analysis include minimal sample preparation, multielement analysis capabilities, detection limits in the low parts per million (ppm) range, and analysis times on the order of 1 min.…

  16. Filter-fluorescer measurement of low-voltage simulator x-ray energy spectra

    SciTech Connect

    Baldwin, G.T.; Craven, R.E.

    1986-01-01

    X-ray energy spectra of the Maxwell Laboratories MBS and Physics International Pulserad 737 were measured using an eight-channel filter-fluorescer array. The PHOSCAT computer code was used to calculate channel response functions, and the UFO code to unfold spectrum.

  17. Energy-Dispersive X-Ray Fluorescence Spectrometry: A Long Overdue Addition to the Chemistry Curriculum

    ERIC Educational Resources Information Center

    Palmer, Peter T.

    2011-01-01

    Portable Energy-Dispersive X-Ray Fluorescence (XRF) analyzers have undergone significant improvements over the past decade. Salient advantages of XRF for elemental analysis include minimal sample preparation, multielement analysis capabilities, detection limits in the low parts per million (ppm) range, and analysis times on the order of 1 min.…

  18. Analysis of titanium and zirconium in red mud with energy dispersive x-ray spectrometry

    SciTech Connect

    Kobya, M.; Ertugrul, M.; Dogan, O.; Simsek, O.

    1996-11-01

    An energy dispersive x-ray fluorescence technique was used for the determination of Titanium (Ti) and Zirconium (Zr) in red mud by using a standard addition method. An annular {sup 241}Am source is employed for excitation of K shells of elements. 13 refs., 2 figs., 1 tab.

  19. Comparison of Anthropometry to Dual Energy X-Ray Absorptiometry: A New Prediction Equation for Women

    ERIC Educational Resources Information Center

    Ball, Stephen; Swan, Pamela D.; DeSimone, Rosemarie

    2004-01-01

    The purpose of this study was to assess the accuracy of three recommended anthropometric equations for women and then develop an updated prediction equation using dual energy x-ray absorptiometry (DXA). The percentage of body fat (%BF) by anthropometry was significantly correlated (r = .896-. 929; p [is less than] .01) with DXA, but each equation…

  20. Comparison of Anthropometry to Dual Energy X-Ray Absorptiometry: A New Prediction Equation for Women

    ERIC Educational Resources Information Center

    Ball, Stephen; Swan, Pamela D.; DeSimone, Rosemarie

    2004-01-01

    The purpose of this study was to assess the accuracy of three recommended anthropometric equations for women and then develop an updated prediction equation using dual energy x-ray absorptiometry (DXA). The percentage of body fat (%BF) by anthropometry was significantly correlated (r = .896-. 929; p [is less than] .01) with DXA, but each equation…

  1. Development of mm2-size high energy resolution X-ray detectors using W-SPT

    NASA Astrophysics Data System (ADS)

    Angloher, G.; Bento, A.; Kraus, H.; Pröbst, F.; Seidel, W.

    2002-02-01

    The low transition temperature of tungsten should allow fabrication of X-ray detectors combining high-energy resolution and enlarged absorber area (~1 mm2). We present first results obtained for lead and gold absorbers read out by tungsten superconducting phase transition thermometers (W-SPT) using a variety of detector geometries. .

  2. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode.

    PubMed

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin; Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-01

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  3. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

    NASA Astrophysics Data System (ADS)

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin; Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-01

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  4. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

    SciTech Connect

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-15

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  5. Energy resolution and high count rate performance of superconducting tunnel junction x-ray spectrometers

    SciTech Connect

    Frank, M.; Hiller, L.J.; le Grand, J.B.; Mears, C.A.; Labov, S.E.; Lindeman, M.A.; Netel, H.; Chow, D.; Barfknecht, A.

    1998-01-01

    We present experimental results obtained with a cryogenically cooled, high-resolution x-ray spectrometer based on a 141{mu}m{times}141{mu}m Nb-Al-Al{sub 2}O{sub 3}-Al-Nb superconducting tunnel junction (STJ) detector in a demonstration experiment. Using monochromatized synchrotron radiation we studied the energy resolution of this energy-dispersive spectrometer for soft x rays with energies between 70 and 700 eV and investigated its performance at count rates up to nearly 60000 cps. At count rates of several 100 cps we achieved an energy resolution of 5.9 eV (FWHM) and an electronic noise of 4.5 eV for 277 eV x rays (the energy corresponding to C K). Increasing the count rate, the resolution 277 eV remained below 10 eV for count rates up to {approximately}10000cps and then degraded to 13 eV at 23000 cps and 20 eV at 50000 cps. These results were achieved using a commercially available spectroscopy amplifier with a baseline restorer. No pile-up rejection was applied in these measurements. Our results show that STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a significantly better energy resolution for soft x rays. Thus STJ detectors may prove very useful in microanalysis, synchrotron x-ray fluorescence (XRF) applications, and XRF analysis of light elements (K lines) and transition elements (L lines). {copyright} {ital 1998 American Institute of Physics.}

  6. Luminescence imaging of water during irradiation of X-ray photons lower energy than Cerenkov- light threshold

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Koyama, Shuji; Komori, Masataka; Toshito, Toshiyuki

    2016-10-01

    Luminescence imaging of water using X-ray photon irradiation at energy lower than maximum energy of ~200 keV is thought to be impossible because the secondary electrons produced in this energy range do not emit Cerenkov- light. Contrary to this consensus assumption, we show that the luminescence imaging of water can be achieved by X-ray irradiation at energy lower than 120 keV. We placed water phantoms on a table with a conventional X-ray imaging system, and luminescence images of these phantoms were measured with a high-sensitivity, cooled charge coupled device (CCD) camera during X-ray photon irradiation at energy below 120 keV. We also carried out such imaging of an acrylic block and plastic scintillator. The luminescence images of water phantoms taken during X-ray photon irradiation clearly showed X-ray photon distribution. The intensity of the X-ray photon images of the phantom increased almost proportionally to the number of X-ray irradiations. Lower-energy X-ray photon irradiation showed lower-intensity luminescence at the deeper parts of the phantom due to the higher X-ray absorption in the water phantom. Furthermore, lower-intensity luminescence also appeared at the deeper parts of the acrylic phantom due to its higher density than water. The intensity of the luminescence for water was 0.005% of that for plastic scintillator. Luminescence imaging of water during X-ray photon irradiation at energy lower than 120 keV was possible. This luminescence imaging method is promising for dose estimation in X-ray imaging systems.

  7. Energy-tunable x-ray diffraction: A tool for depth profiling in polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Zolotoyabko, E.; Quintana, J. P.

    2002-03-01

    We have developed a new variant of depth-sensitive x-ray diffraction technique to study structural parameters in inhomogeneous polycrystalline materials. In this method, diffraction patterns are measured at different x-ray energies which are varied by small steps, and then the depth-resolved structural characteristics are retrieved from the energy-dependent x-ray diffraction data. In the current articles, this approach is applied to extract preferred orientation with depth resolution. In the case of uniaxial preferred orientation, the analytical algorithm has been developed based on March functions. Application of this technique to seashells allowed us to characterize the microstructure evolution in the nacre layer. Near the inner surface, adjacent to the mollusk mantle, the nacre consists of well-defined lamellas which reveal a high degree of the (001)-preferred orientation. This preferred orientation deteriorates in depth due to the accumulation of cracks and other imperfections. The texture distribution is characterized quantitatively by depth-dependent March parameters, which allows us to compare samples taken from different shells. In a similar way, energy-variable x-ray diffraction can be used for nondestructive characterization of a very broad spectrum of laminated structures and composite materials and systems.

  8. A new approach to synchrotron energy-dispersive X-ray diffraction computed tomography.

    PubMed

    Lazzari, Olivier; Egan, Christopher K; Jacques, Simon D M; Sochi, Taha; Di Michiel, Marco; Cernik, Robert J; Barnes, Paul

    2012-07-01

    A new data collection strategy for performing synchrotron energy-dispersive X-ray diffraction computed tomography has been devised. This method is analogous to angle-dispersive X-ray diffraction whose diffraction signal originates from a line formed by intersection of the incident X-ray beam and the sample. Energy resolution is preserved by using a collimator which defines a small sampling voxel. This voxel is translated in a series of parallel straight lines covering the whole sample and the operation is repeated at different rotation angles, thus generating one diffraction pattern per translation and rotation step. The method has been tested by imaging a specially designed phantom object, devised to be a demanding validator for X-ray diffraction imaging. The relative strengths and weaknesses of the method have been analysed with respect to the classic angle-dispersive technique. The reconstruction accuracy of the method is good, although an absorption correction is required for lower energy diffraction because of the large path lengths involved. The spatial resolution is only limited to the width of the scanning beam owing to the novel collection strategy. The current temporal resolution is poor, with a scan taking several hours. The method is best suited to studying large objects (e.g. for engineering and materials science applications) because it does not suffer from diffraction peak broadening effects irrespective of the sample size, in contrast to the angle-dispersive case.

  9. Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

    NASA Astrophysics Data System (ADS)

    O'Flynn, D.; Bellazzini, R.; Minuti, M.; Brez, A.; Pinchera, M.; Spandre, G.; Moss, R.; Speller, R. D.

    2017-01-01

    X-ray diffraction (XRD) is a powerful tool for material identification. In order to interpret XRD data, knowledge is required of the scattering angles and energies of X-rays which interact with the sample. By using a pixellated, energy-resolving detector, this knowledge can be gained when using a spectrum of unfiltered X-rays, and without the need to collimate the scattered radiation. Here we present results of XRD measurements taken with the Pixirad detector and a laboratory-based X-ray source. The cadmium telluride sensor allows energy windows to be selected, and the 62 μm pixel pitch enables accurate spatial information to be preserved for XRD measurements, in addition to the ability to take high resolution radiographic images. Diffraction data are presented for a variety of samples to demonstrate the capability of the technique for materials discrimination in laboratory, security and pharmaceutical environments. Distinct diffraction patterns were obtained, from which details on the molecular structures of the items under study were determined.

  10. Hard X-ray measurement from a plasma focus of low energy

    NASA Astrophysics Data System (ADS)

    Silva, Patricio; Farías, Cristián; L'Huissier, Patricio; Pinto, Victor; Zambra, Marcelo; Soto, Leopoldo

    2008-11-01

    Hard X-ray emission in the plasma focus device PF-400J [1-3] is studied using a stepped filters array of different materials and thickness leaned to a radiographic commercial cassette, Agfa Curix [4, 5]. This diagnostic is located in the axial symmetrical axis at 45 cm away from pinch zone. Different targets are used (Cu, Mo, Ag, Pb) at the bottom of the central hole of the anode. The device was run using Hydrogen like filling gas at a charging voltage between 28 kV to 30 kV. Accumulating X radiation over a X-ray film by means of a sequence of electrical discharges, effective energies are obtained whose values are between 30 keV to close 100 keV. The obtained energy is discussed and interpreted like an effective energy, when it is compared with the results that would be obtained by means of X-ray generators based on a conventional accelerator. X-ray photographies of organic bodies are obtained showing possible applications.

  11. Low-Energy Microfocus X-Ray Source for Enhanced Testing Capability in the Stray Light Facility

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; O'Dell, Stephen; Kolodziejczak, Jeff

    2015-01-01

    Research toward high-resolution, soft x-ray optics (mirrors and gratings) necessary for the next generation large x-ray observatories requires x-ray testing using a low-energy x-ray source with fine angular size (<1 arcsecond). To accommodate this somewhat demanding requirement, NASA Marshall Space Flight Center (MSFC) has procured a custom, windowless low-energy microfocus (approximately 0.1 mm spot) x-ray source from TruFocus Corporation that mates directly to the Stray Light Facility (SLF). MSFC X-ray Astronomy team members are internationally recognized for their expertise in the development, fabrication, and testing of grazing-incidence optics for x-ray telescopes. One of the key MSFC facilities for testing novel x-ray instrumentation is the SLF. This facility is an approximately 100-m-long beam line equipped with multiple x-ray sources and detectors. This new source adds to the already robust compliment of instrumentation, allowing MSFC to support additional internal and community x-ray testing needs.

  12. Response of large area avalanche photodiodes to low energy x rays.

    PubMed

    Gentile, T R; Bales, M; Arp, U; Dong, B; Farrell, R

    2012-05-01

    For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) near liquid nitrogen temperature to detect x rays with energies between 0.2 keV and 20 keV. Whereas there are numerous reports of x ray spectrometry using APDs at energies above 1 keV, operation near liquid nitrogen temperature allowed us to reach a nominal threshold of 0.1 keV. However, due to the short penetration depth of x rays below 1 keV, the pulse height spectrum of the APD become complex. We studied the response using monochromatic x ray beams and employed phenomenological fits of the pulse height spectrum to model the measurement of a continuum spectrum from a synchrotron. In addition, the measured pulse height spectrum was modelled using a profile for the variation in efficiency of collection of photoelectrons with depth into the APD. The best results are obtained with the collection efficiency model.

  13. CT dual-energy decomposition into x-ray signatures ρe and Ze

    NASA Astrophysics Data System (ADS)

    Martz, Harry E.; Seetho, Issac M.; Champley, Kyle E.; Smith, Jerel A.; Azevedo, Stephen G.

    2016-05-01

    In a recent journal article [IEEE Trans. Nuc. Sci., 63(1), 341-350, 2016], we introduced a novel method that decomposes dual-energy X-ray CT (DECT) data into electron density (ρe) and a new effective-atomic-number called Ze in pursuit of system-independent characterization of materials. The Ze of a material, unlike the traditional Zeff, is defined relative to the actual X-ray absorption properties of the constituent atoms in the material, which are based on published X-ray cross sections. Our DECT method, called SIRZ (System-Independent ρe, Ze), uses a set of well-known reference materials and an understanding of the system spectral response to produce accurate and precise estimates of the X-ray-relevant basis variables (ρe, Ze) regardless of scanner or spectra in diagnostic energy ranges (30 to 200 keV). Potentially, SIRZ can account for and correct spectral changes in a scanner over time and, because the system spectral response is included in the technique, additional beam-hardening correction is not needed. Results show accuracy (<3%) and precision (<2%) values that are much better than prior methods on a wide range of spectra. In this paper, we will describe how to convert DECT system output into (ρe, Ze) features and we present our latest SIRZ results compared with ground truth for a set of materials.

  14. Absolute pulse energy measurements of soft x-rays at the Linac Coherent Light Source.

    PubMed

    Tiedtke, K; Sorokin, A A; Jastrow, U; Juranić, P; Kreis, S; Gerken, N; Richter, M; Arp, U; Feng, Y; Nordlund, D; Soufli, R; Fernández-Perea, M; Juha, L; Heimann, P; Nagler, B; Lee, H J; Mack, S; Cammarata, M; Krupin, O; Messerschmidt, M; Holmes, M; Rowen, M; Schlotter, W; Moeller, S; Turner, J J

    2014-09-08

    This paper reports novel measurements of x-ray optical radiation on an absolute scale from the intense and ultra-short radiation generated in the soft x-ray regime of a free electron laser. We give a brief description of the detection principle for radiation measurements which was specifically adapted for this photon energy range. We present data characterizing the soft x-ray instrument at the Linac Coherent Light Source (LCLS) with respect to the radiant power output and transmission by using an absolute detector temporarily placed at the downstream end of the instrument. This provides an estimation of the reflectivity of all x-ray optical elements in the beamline and provides the absolute photon number per bandwidth per pulse. This parameter is important for many experiments that need to understand the trade-offs between high energy resolution and high flux, such as experiments focused on studying materials via resonant processes. Furthermore, the results are compared with the LCLS diagnostic gas detectors to test the limits of linearity, and observations are reported on radiation contamination from spontaneous undulator radiation and higher harmonic content.

  15. Development of optics for x-ray phase-contrast imaging of high energy density plasmas

    SciTech Connect

    Stutman, D.; Finkenthal, M.; Moldovan, N.

    2010-10-15

    Phase-contrast or refraction-enhanced x-ray radiography can be useful for the diagnostic of low-Z high energy density plasmas, such as imploding inertial confinement fusion (ICF) pellets, due to its sensitivity to density gradients. To separate and quantify the absorption and refraction contributions to x-ray images, methods based on microperiodic optics, such as shearing interferometry, can be used. To enable applying such methods with the energetic x rays needed for ICF radiography, we investigate a new type of optics consisting of grazing incidence microperiodic mirrors. Using such mirrors, efficient phase-contrast imaging systems could be built for energies up to {approx}100 keV. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors based on the difference in the total reflection between a low-Z substrate and a high-Z film. Prototype mirrors fabricated with this method show promising characteristics in laboratory tests.

  16. Response of large area avalanche photodiodes to low energy x rays

    SciTech Connect

    Gentile, T. R.; Bales, M.; Arp, U.; Dong, B.; Farrell, R.

    2012-05-15

    For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) near liquid nitrogen temperature to detect x rays with energies between 0.2 keV and 20 keV. Whereas there are numerous reports of x ray spectrometry using APDs at energies above 1 keV, operation near liquid nitrogen temperature allowed us to reach a nominal threshold of 0.1 keV. However, due to the short penetration depth of x rays below 1 keV, the pulse height spectrum of the APD become complex. We studied the response using monochromatic x ray beams and employed phenomenological fits of the pulse height spectrum to model the measurement of a continuum spectrum from a synchrotron. In addition, the measured pulse height spectrum was modelled using a profile for the variation in efficiency of collection of photoelectrons with depth into the APD. The best results are obtained with the collection efficiency model.

  17. What is the nature of the high energy X-ray sources in the galaxy?

    NASA Astrophysics Data System (ADS)

    Cuturilo, Sophie; Tomsick, John; Clavel, Maica; Lansbury, George B.

    2017-01-01

    Finding sources of high energy “hard” X-rays allow us to probe the most extreme conditions in the Universe. Such sources include accreting black holes and neutron stars, where we find the strongest gravitational and magnetic fields, as well as pulsars and supernova remnants, where particles are accelerated to produce the hard X-rays. Over the past decade, the INTEGRAL satellite ahs been discovering new high energy sources, and this has allowed us to understand the population of bright hard X-ray sources. Over the past few years, the NuSTAR satellite, with much better sensitivity than INTEGRAL, has been allowing us to find even more hard X-ray sources, and we will present results from studies of sources discovered in the NuSTAR serendipitous source survey. We analyzed seven different potential sources looking for counterparts using NuSTAR, Chandra and ground based optical/NIR observations. Of the seven, two have confirmed counterparts and five need either an optical/NIR detection or further spectroscopy.

  18. An evaluation of high energy bremsstrahlung background in point-projection x-ray radiography experiments.

    PubMed

    Krauland, C M; Jarrott, L C; Drake, R P; Keiter, P A; Kuranz, C C; Westover, B; Sawada, H; Kaczala, D N; Bonofiglo, P

    2012-10-01

    Backlit pinhole x-ray radiography has provided high-resolution images in many recent high-energy-density laser experiments. Its aim is to image the object of interest with a roughly monochromatic Kα source. However, despite the high intrinsic brightness achieved by the technique, data on x-ray film have shown a signal to background ratio near one, with data on image plates producing a higher background. This has been attributed, without direct evidence, to the interaction of suprathermal electrons with the (high Z) pinhole substrate. We present here the first direct measurement of the hard x-rays produced by such a backlighter target and a test of an approach to reducing the background. Specifically, a thick, low-Z layer was added on the side of the substrate toward the detector, intended to stop the energetic electrons and produce smaller emissions. Results from the Omega-60 laser experiment showed that the oft-seen background signal is in the range of 60-80 keV, a plausible energy range for energetic electrons produced in the laser-irradiated plasma. It also showed a comparable level of background signal in both types of targets. The work presented here includes target design and motivating theory, as well as the unexpected findings about x-ray background production.

  19. Development of optics for x-ray phase-contrast imaging of high energy density plasmas.

    PubMed

    Stutman, D; Finkenthal, M; Moldovan, N

    2010-10-01

    Phase-contrast or refraction-enhanced x-ray radiography can be useful for the diagnostic of low-Z high energy density plasmas, such as imploding inertial confinement fusion (ICF) pellets, due to its sensitivity to density gradients. To separate and quantify the absorption and refraction contributions to x-ray images, methods based on microperiodic optics, such as shearing interferometry, can be used. To enable applying such methods with the energetic x rays needed for ICF radiography, we investigate a new type of optics consisting of grazing incidence microperiodic mirrors. Using such mirrors, efficient phase-contrast imaging systems could be built for energies up to ∼100 keV. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors based on the difference in the total reflection between a low-Z substrate and a high-Z film. Prototype mirrors fabricated with this method show promising characteristics in laboratory tests.

  20. High-Energy Density science with an ultra-bright x-ray laser

    NASA Astrophysics Data System (ADS)

    Glenzer, Siegfried

    2015-11-01

    This talk will review recent progress in high-energy density physics using the world's brightest x-ray source, the Linac Coherent Light Source, SLAC's free electron x-ray laser. These experiments investigate laser-driven matter in extreme conditions where powerful x-ray scattering and imaging techniques have been applied to resolve ionic interactions at atomic (Ångstrom) scale lengths and to visualize the formation of dense plasma states. Major research areas include dynamic compression experiments of solid targets to determine structural properties and to discover and characterize phase transitions at mega-bar pressures. A second area studies extreme fields produced by high-intensity radiation where fundamental questions of laboratory plasmas can be related to cosmological phenomena. Each of these areas takes advantage of the unique properties of the LCLS x-ray beam. They include small foci for achieving high intensity or high spatial resolution, high photon flux for dynamic structure factor measurements in single shots, and high spectral bandwidth to resolve plasmon (Langmuir) waves or ion acoustic waves in dense plasmas. We will further describe new developments of ultrafast pump-probe technique at high repetition rates. These include studies on dense cryogenic hydrogen that have begun providing fundamental insights into the physical properties of matter in extreme conditions that are important for astrophysics, fusion experiments and generation of radiation sources. This work was supported by DOE Office of Science, Fusion Energy Science under FWP 100182.

  1. High-energy neutrino fluxes from AGN populations inferred from X-ray surveys

    NASA Astrophysics Data System (ADS)

    Jacobsen, Idunn B.; Wu, Kinwah; On, Alvina Y. L.; Saxton, Curtis J.

    2015-08-01

    High-energy neutrinos and photons are complementary messengers, probing violent astrophysical processes and structural evolution of the Universe. X-ray and neutrino observations jointly constrain conditions in active galactic nuclei (AGN) jets: their baryonic and leptonic contents, and particle production efficiency. Testing two standard neutrino production models for local source Cen A (Koers & Tinyakov and Becker & Biermann), we calculate the high-energy neutrino spectra of single AGN sources and derive the flux of high-energy neutrinos expected for the current epoch. Assuming that accretion determines both X-rays and particle creation, our parametric scaling relations predict neutrino yield in various AGN classes. We derive redshift-dependent number densities of each class, from Chandra and Swift/BAT X-ray luminosity functions (Silverman et al. and Ajello et al.). We integrate the neutrino spectrum expected from the cumulative history of AGN (correcting for cosmological and source effects, e.g. jet orientation and beaming). Both emission scenarios yield neutrino fluxes well above limits set by IceCube (by ˜4-106 × at 1 PeV, depending on the assumed jet models for neutrino production). This implies that: (i) Cen A might not be a typical neutrino source as commonly assumed; (ii) both neutrino production models overestimate the efficiency; (iii) neutrino luminosity scales with accretion power differently among AGN classes and hence does not follow X-ray luminosity universally; (iv) some AGN are neutrino-quiet (e.g. below a power threshold for neutrino production); (v) neutrino and X-ray emission have different duty cycles (e.g. jets alternate between baryonic and leptonic flows); or (vi) some combination of the above.

  2. The energy spectrum of X-rays from rocket-triggered lightning

    NASA Astrophysics Data System (ADS)

    Arabshahi, S.; Dwyer, J. R.; Cramer, E. S.; Grove, J. E.; Gwon, C.; Hill, J. D.; Jordan, D. M.; Lucia, R. J.; Vodopiyanov, I. B.; Uman, M. A.; Rassoul, H. K.

    2015-10-01

    Although the production of X-rays from natural and rocket-triggered lightning leaders have been studied in detail over the last 10 years, the energy spectrum of the X-rays has never been well measured because the X-rays are emitted in very short but intense bursts that result in pulse pileup in the detectors. The energy spectrum is important because it provides information about the source mechanism for producing the energetic runaway electrons and about the electric fields that they traverse. We have recently developed and operated the first spectrometer for the energetic radiation from lightning. The instrument is part of the Atmospheric Radiation Imagery and Spectroscopy (ARIS) project and will be referred to as ARIS-S (ARIS Spectrometer). It consists of seven 3'' NaI(Tl)/photomultiplier tube scintillation detectors with different thicknesses of attenuators, ranging from no attenuator to more than 1'' of lead placed over the detector (all the detectors are in a 1/8'' thick aluminum box). Using X-ray pulses preceding 48 return strokes in 8 rocket-triggered lightnings, we found that the spectrum of X-rays from leaders is too soft to be consistent with Relativistic Runaway Electron Avalanche. It has a power law dependence on the energies of the photons, and the power index, λ, is between 2.5 and 3.5. We present the details of the design of the instrument and the results of the analysis of the lightning data acquired during the summer of 2012.

  3. Robust x-ray based material identification using multi-energy sinogram decomposition

    NASA Astrophysics Data System (ADS)

    Yuan, Yaoshen; Tracey, Brian; Miller, Eric

    2016-05-01

    There is growing interest in developing X-ray computed tomography (CT) imaging systems with improved ability to discriminate material types, going beyond the attenuation imaging provided by most current systems. Dual- energy CT (DECT) systems can partially address this problem by estimating Compton and photoelectric (PE) coefficients of the materials being imaged, but DECT is greatly degraded by the presence of metal or other materials with high attenuation. Here we explore the advantages of multi-energy CT (MECT) systems based on photon-counting detectors. The utility of MECT has been demonstrated in medical applications where photon- counting detectors allow for the resolution of absorption K-edges. Our primary concern is aviation security applications where K-edges are rare. We simulate phantoms with differing amounts of metal (high, medium and low attenuation), both for switched-source DECT and for MECT systems, and include a realistic model of detector energy 0 resolution. We extend the DECT sinogram decomposition method of Ying et al. to MECT, allowing estimation of separate Compton and photoelectric sinograms. We furthermore introduce a weighting based on a quadratic approximation to the Poisson likelihood function that deemphasizes energy bins with low signal. Simulation results show that the proposed approach succeeds in estimating material properties even in high-attenuation scenarios where the DECT method fails, improving the signal to noise ratio of reconstructions by over 20 dB for the high-attenuation phantom. Our work demonstrates the potential of using photon counting detectors for stably recovering material properties even when high attenuation is present, thus enabling the development of improved scanning systems.

  4. Feasibility of using intermediate x-ray energies for highly conformal extracranial radiotherapy

    SciTech Connect

    Dong, Peng; Yu, Victoria; Nguyen, Dan; Demarco, John; Low, Daniel A.; Sheng, Ke; Woods, Kaley; Boucher, Salime

    2014-04-15

    Purpose: To investigate the feasibility of using intermediate energy 2 MV x-rays for extracranial robotic intensity modulated radiation therapy. Methods: Two megavolts flattening filter free x-rays were simulated using the Monte Carlo code MCNP (v4c). A convolution/superposition dose calculation program was tuned to match the Monte Carlo calculation. The modeled 2 MV x-rays and actual 6 MV flattened x-rays from existing Varian Linacs were used in integrated beam orientation and fluence optimization for a head and neck, a liver, a lung, and a partial breast treatment. A column generation algorithm was used for the intensity modulation and beam orientation optimization. Identical optimization parameters were applied in three different planning modes for each site: 2, 6 MV, and dual energy 2/6 MV. Results: Excellent agreement was observed between the convolution/superposition and the Monte Carlo calculated percent depth dose profiles. For the patient plans, overall, the 2/6 MV x-ray plans had the best dosimetry followed by 2 MV only and 6 MV only plans. Between the two single energy plans, the PTV coverage was equivalent but 2 MV x-rays improved organs-at-risk sparing. For the head and neck case, the 2MV plan reduced lips, mandible, tongue, oral cavity, brain, larynx, left and right parotid gland mean doses by 14%, 8%, 4%, 14%, 24%, 6%, 30% and 16%, respectively. For the liver case, the 2 MV plan reduced the liver and body mean doses by 17% and 18%, respectively. For the lung case, lung V20, V10, and V5 were reduced by 13%, 25%, and 30%, respectively. V10 of heart with 2 MV plan was reduced by 59%. For the partial breast treatment, the 2 MV plan reduced the mean dose to the ipsilateral and contralateral lungs by 27% and 47%, respectively. The mean body dose was reduced by 16%. Conclusions: The authors showed the feasibility of using flattening filter free 2 MV x-rays for extracranial treatments as evidenced by equivalent or superior dosimetry compared to 6 MV plans

  5. Hiresmon: A Fast High Resolution Beam Position Monitor for Medium Hard and Hard X-Rays

    SciTech Connect

    Menk, Ralf Hendrik; Giuressi, Dario; Arfelli, Fulvia; Rigon, Luigi

    2007-01-19

    The high-resolution x-ray beam position monitor (XBPM) is based on the principle of a segmented longitudinal ionization chamber with integrated readout and USB2 link. In contrast to traditional transversal ionization chambers here the incident x-rays are parallel to the collecting field which allows absolute intensity measurements with a precision better than 0.3 %. Simultaneously the beam position in vertical and horizontal direction can be measured with a frame rate of one kHz. The precision of position encoding depends only on the SNR of the synchrotron radiation and is in the order of micro meters at one kHz frame rate and 108 photon /sec at 9 KeV.

  6. Optimum energy window setting on Hg-201 x-rays photopeak for effective Tl-201 imaging.

    PubMed

    Kojima, Akihiro; Takaki, Akihiro; Noguchi, Teruya; Matsumoto, Masanori; Katsuda, Noboru; Tomiguchi, Seiji; Yamashita, Yasuyuki

    2005-10-01

    For more effective Tl-201 imaging, the location and width of the energy window set on the Hg-201 x-rays photopeak was investigated using Monte Carlo simulation and phantom experiments. We calculated energy spectra and investigated the amount of primary and scattered photons within various energy windows set on the x-rays photopeak. The energy resolution (ER) at 71 keV (the peak of the x-rays photopeak) was changed to 10%, 12%, 14% and 16%. The relationships between the energy window and the primary counts rate or the scatter fraction (= scattered counts/primary counts, SF) were obtained. By compromise between the primary counts rate and the SF for ER = 12%, the optimum energy window was determined as a wider off-peak window, 77 keV +/- 14.3% (66-88 keV). This off-peak window increased the primary counts rate by 12.5% and decreased the SF by -17% as compared with the conventional on-peak energy window (71 keV +/- 10%, 64-78 keV). When this off-peak widow acquisition was compared with the conventional on-peak window one on a gamma camera, planar and SPECT images using the off-peak widow clearly showed superior results qualitatively and quantitatively.

  7. In Situ Soft X-ray Spectroscopy Characterization of Interfacial Phenomena in Energy Materials and Devices

    NASA Astrophysics Data System (ADS)

    Guo, Jinghua; Liu, Yi-Sheng; Kapilashrami, Mukes; Glans, Per-Anders; Bora, Debajeet; Braun, Artur; Velasco Vélez, Juan Jesús; Salmeron, Miquel; ALS/LBNL Team; EMPA, MSD/LBNL Collaboration

    2015-03-01

    Advanced energy technology arises from the understanding in basic science, thus rest in large on in-situ/operando characterization tools for observing the physical and chemical interfacial processes, which has been largely limited in a framework of thermodynamic and kinetic concepts or atomic and nanoscale. In many important energy systems such as energy conversion, energy storage and catalysis, advanced materials and functionality in devices are based on the complexity of material architecture, chemistry and interactions among constituents within. To understand and thus ultimately control the energy conversion and energy storage applications calls for in-situ/operando characterization tools. Soft X-ray spectroscopy offers a number of very unique features. We will present our development of the in-situ/operando soft X-ray spectroscopic tools of catalytic and electrochemical reactions in recent years, and reveal how to overcome the challenge that soft X-rays cannot easily peek into the high-pressure catalytic cells or liquid electrochemical cells. In this presentation a number of examples are given, including the nanocatalysts and the recent experiment performed for studying the hole generation in a specifically designed photoelectrochemical cell under operando conditions. The ALS is supported by the the U.S. Department of Energy.

  8. Tilted angle CZT detector for photon counting/energy weighting x-ray and CT imaging.

    PubMed

    Shikhaliev, Polad M

    2006-09-07

    X-ray imaging with a photon counting/energy weighting detector can provide the highest signal to noise ratio (SNR). Scanning slit/multi-slit x-ray image acquisition can provide a dose-efficient scatter rejection, which increases SNR. Use of a photon counting/energy weighting detector in a scanning slit/multi-slit acquisition geometry could provide highest possible dose efficiency in x-ray and CT imaging. Currently, the most advanced photon counting detector is the cadmium zinc telluride (CZT) detector, which, however, is suboptimal for energy resolved x-ray imaging. A tilted angle CZT detector is proposed in this work for applications in photon counting/energy weighting x-ray and CT imaging. In tilted angle configuration, the x-ray beam hits the surface of the linear array of CZT crystals at a small angle. This allows the use of CZT crystals of a small thickness while maintaining the high photon absorption. Small thickness CZT detectors allow for a significant decrease in the polarization effect in the CZT volume and an increase in count rate. The tilted angle CZT with a small thickness also provides higher spatial and energy resolution, and shorter charge collection time, which potentially enables fast energy resolving x-ray image acquisition. In this work, the major performance parameters of the tilted angle CZT detector, including its count rate, spatial resolution and energy resolution, were evaluated. It was shown that for a CZT detector with a 0.7 mm thickness and 13 degrees tilting angle, the maximum count rate can be increased by 10.7 times, while photon absorption remains >90% at photon energies up to 120 keV. Photon counting/energy weighting x-ray imaging using a tilted angle CZT detector was simulated. SNR improvement due to optimal photon energy weighting was 23% and 14% when adipose contrast element, inserted in soft tissue with 10 cm and 20 cm thickness, respectively, was imaged using 5 energy bins and weighting factors optimized for the adipose. SNR

  9. Tilted angle CZT detector for photon counting/energy weighting x-ray and CT imaging

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2006-09-01

    X-ray imaging with a photon counting/energy weighting detector can provide the highest signal to noise ratio (SNR). Scanning slit/multi-slit x-ray image acquisition can provide a dose-efficient scatter rejection, which increases SNR. Use of a photon counting/energy weighting detector in a scanning slit/multi-slit acquisition geometry could provide highest possible dose efficiency in x-ray and CT imaging. Currently, the most advanced photon counting detector is the cadmium zinc telluride (CZT) detector, which, however, is suboptimal for energy resolved x-ray imaging. A tilted angle CZT detector is proposed in this work for applications in photon counting/energy weighting x-ray and CT imaging. In tilted angle configuration, the x-ray beam hits the surface of the linear array of CZT crystals at a small angle. This allows the use of CZT crystals of a small thickness while maintaining the high photon absorption. Small thickness CZT detectors allow for a significant decrease in the polarization effect in the CZT volume and an increase in count rate. The tilted angle CZT with a small thickness also provides higher spatial and energy resolution, and shorter charge collection time, which potentially enables fast energy resolving x-ray image acquisition. In this work, the major performance parameters of the tilted angle CZT detector, including its count rate, spatial resolution and energy resolution, were evaluated. It was shown that for a CZT detector with a 0.7 mm thickness and 13° tilting angle, the maximum count rate can be increased by 10.7 times, while photon absorption remains >90% at photon energies up to 120 keV. Photon counting/energy weighting x-ray imaging using a tilted angle CZT detector was simulated. SNR improvement due to optimal photon energy weighting was 23% and 14% when adipose contrast element, inserted in soft tissue with 10 cm and 20 cm thickness, respectively, was imaged using 5 energy bins and weighting factors optimized for the adipose. SNR

  10. X-ray lasers and methods utilizing two component driving illumination provided by optical laser means of relatively low energy and small physical size

    DOEpatents

    Rosen, Mordecai D.; Matthews, Dennis L.

    1991-01-01

    An X-ray laser (10), and related methodology, are disclosed wherein an X-ray laser target (12) is illuminated with a first pulse of optical laser radiation (14) of relatively long duration having scarcely enough energy to produce a narrow and linear cool plasma of uniform composition (38). A second, relatively short pulse of optical laser radiation (18) is uniformly swept across the length, from end to end, of the plasma (38), at about the speed of light, to consecutively illuminate continuously succeeding portions of the plasma (38) with optical laser radiation having scarcely enough energy to heat, ionize, and invert them into the continuously succeeding portions of an X-ray gain medium. This inventive double pulse technique results in a saving of more than two orders of magnitude in driving optical laser energy, when compared to the conventional single pulse approach.

  11. High-energy Neutrino Flares from X-Ray Bright and Dark Tidal Disruption Events

    NASA Astrophysics Data System (ADS)

    Senno, Nicholas; Murase, Kohta; Mészáros, Peter

    2017-03-01

    X-ray and γ-ray observations by the Swift satellite revealed that a fraction of tidal disruption events (TDEs) have relativistic jets. Jetted TDEs have been considered to be potential sources of very-high-energy cosmic-rays and neutrinos. In this work, using semi-analytical methods, we calculate neutrino spectra of X-ray bright TDEs with powerful jets and dark TDEs with possible choked jets, respectively. We estimate their neutrino fluxes and find that non-detection would give us an upper limit on the baryon loading of the jet luminosity contained in cosmic-rays ξ cr ≲ 20–50 for Sw J1644+57. We show that X-ray bright TDEs make a sub-dominant (≲5%–10%) contribution to IceCube’s diffuse neutrino flux, and study possible contributions of X-ray dark TDEs given that particles are accelerated in choked jets or disk winds. We discuss future prospects for multi-messenger searches of the brightest TDEs.

  12. Sample preparation of energy materials for X-ray nanotomography with micromanipulation.

    PubMed

    Chen-Wiegart, Yu-chen Karen; Camino, Fernando E; Wang, Jun

    2014-06-06

    X-ray nanotomography presents an unprecedented opportunity to study energy storage/conversion materials at nanometer scales in three dimensions, with both elemental and chemical sensitivity. A critical step in obtaining high-quality X-ray nanotomography data is reliable sample preparation to ensure that the entire sample fits within the field of view of the X-ray microscope. Although focused-ion-beam lift-out has previously been used for large sample (few to tens of microns) preparation, a difficult undercut and lift-out procedure results in a time-consuming sample preparation process. Herein, we propose a much simpler and direct sample preparation method to resolve the issues that block the view of the sample base after milling and during the lift-out process. This method is applied on a solid-oxide fuel cell and a lithium-ion battery electrode, before numerous critical 3D morphological parameters are extracted, which are highly relevant to their electrochemical performance. A broad application of this method for microstructure study with X-ray nanotomography is discussed and presented.

  13. The nuclear spectroscopic telescope array (NuSTAR) high-energy X-ray mission

    NASA Astrophysics Data System (ADS)

    Madsen, Kristin K.; Harrison, Fiona A.; An, Hongjun; Boggs, Steven E.; Christensen, Finn E.; Cook, Rick; Craig, William W.; Forster, Karl; Fuerst, Felix; Grefenstette, Brian; Hailey, Charles J.; Kitaguchi, Takao; Markwardt, Craig; Mao, Peter; Miyasaka, Hiromasa; Rana, Vikram R.; Stern, Daniel K.; Zhang, William W.; Zoglauer, Andreas; Walton, Dominic; Westergaard, Niels J.

    2014-07-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) mission was launched on 2012 June 13 and is the first focusing high-energy X-ray telescope in orbit operating above ~10 keV. NuSTAR flies two co-aligned Wolter-I conical approximation X-ray optics, coated with Pt/C and W/Si multilayers, and combined with a focal length of 10.14 meters this enables operation from 3-79 keV. The optics focus onto two focal plane arrays, each consisting of 4 CdZnTe pixel detectors, for a field of view of 12.5 arcminutes. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity, and with an effective point spread function FWHM of 18 arcseconds (HPD ~1), NuSTAR provides a leap of improvement in resolution over the collimated or coded mask instruments that have operated in this bandpass. We present in-orbit performance details of the observatory and highlight important science results from the first two years of the mission.

  14. The Nuclear Spectroscopic Telescope Array (NuSTAR) High-Energy X-ray Mission

    NASA Technical Reports Server (NTRS)

    Harrison, Fiona A.; Craig, Willliam W.; Christensen, Finn E.; Hailey, Charles J.; Zhang, William W.; Boggs, Steven E.; Stern, Daniel; Cook, W. Rick; Forster, Karl; Giommi, Paolo; hide

    2013-01-01

    High-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the 10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to thepeak epoch of galaxy assembly in the universe (at z 2) by surveying selected regions of the sky; (2) study the population of hard X-ray-emitting compact objects in the Galaxy by mapping the central regions of the Milky Way; (3) study the non-thermal radiation in young supernova remnants, both the hard X-ray continuum and the emission from the radioactive element 44Ti; (4) observe blazars contemporaneously with ground-based radio, optical, and TeV telescopes, as well as with Fermi and Swift, to constrain the structure of AGN jets; and (5) observe line and continuum emission from core-collapse supernovae in the Local Group, and from nearby Type Ia events, to constrain explosion models. During its baseline two-year mission, NuSTAR will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6 inclination orbit, the observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an expected orbit lifetime of 10 yr, we anticipate proposing a guest investigator program, to begin in late 2014.

  15. THE NUCLEAR SPECTROSCOPIC TELESCOPE ARRAY (NuSTAR) HIGH-ENERGY X-RAY MISSION

    SciTech Connect

    Harrison, Fiona A.; Cook, W. Rick; Forster, Karl; Grefenstette, Brian W.; Madsen, Kristin K.; Mao, Peter H.; Miyasaka, Hiromasa; Craig, William W.; Pivovaroff, Michael J.; Christensen, Finn E.; Hailey, Charles J.; Koglin, Jason E.; Mori, Kaya; Zhang, William W.; Boggs, Steven E.; Stern, Daniel; Kim, Yunjin; Giommi, Paolo; Perri, Matteo; and others

    2013-06-20

    The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the {approx}10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to the peak epoch of galaxy assembly in the universe (at z {approx}< 2) by surveying selected regions of the sky; (2) study the population of hard X-ray-emitting compact objects in the Galaxy by mapping the central regions of the Milky Way; (3) study the non-thermal radiation in young supernova remnants, both the hard X-ray continuum and the emission from the radioactive element {sup 44}Ti; (4) observe blazars contemporaneously with ground-based radio, optical, and TeV telescopes, as well as with Fermi and Swift, to constrain the structure of AGN jets; and (5) observe line and continuum emission from core-collapse supernovae in the Local Group, and from nearby Type Ia events, to constrain explosion models. During its baseline two-year mission, NuSTAR will also undertake a broad program of targeted observations. The observatory consists of two co-aligned grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis stabilized spacecraft. Deployed into a 600 km, near-circular, 6 Degree-Sign inclination orbit, the observatory has now completed commissioning, and is performing consistent with pre-launch expectations. NuSTAR is now executing its primary science mission, and with an

  16. Novel energy resolving x-ray pinhole camera on Alcator C-Mod

    SciTech Connect

    Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.; Ellis, R.; Hill, K. W.; Brandstetter, S.; Eikenberry, E.; Hofer, P.; Schneebeli, M.

    2012-10-15

    A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of Almost-Equal-To 1 cm, an energy resolution of Almost-Equal-To 1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

  17. Novel energy resolving x-ray pinhole camera on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.; Brandstetter, S.; Eikenberry, E.; Ellis, R.; Hill, K. W.; Hofer, P.; Schneebeli, M.

    2012-10-01

    A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009), 10.1107/S0909049509009911] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

  18. Novel energy resolving x-ray pinhole camera on Alcator C-Mod.

    PubMed

    Pablant, N A; Delgado-Aparicio, L; Bitter, M; Brandstetter, S; Eikenberry, E; Ellis, R; Hill, K W; Hofer, P; Schneebeli, M

    2012-10-01

    A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

  19. Comparison of neutron and high-energy X-ray dual-beam radiography for air cargo inspection.

    PubMed

    Liu, Y; Sowerby, B D; Tickner, J R

    2008-04-01

    Dual-beam radiography techniques utilising various combinations of high-energy X-rays and neutrons are attractive for screening bulk cargo for contraband such as narcotics and explosives. Dual-beam radiography is an important enhancement to conventional single-beam X-ray radiography systems in that it provides additional information on the composition of the object being imaged. By comparing the attenuations of transmitted dual high-energy beams, it is possible to build a 2D image, colour coded to indicate material. Only high-energy X-rays, gamma-rays and neutrons have the required penetration to screen cargo containers. This paper reviews recent developments and applications of dual-beam radiography for air cargo inspection. These developments include dual high-energy X-ray techniques as well as fast neutron and gamma-ray (or X-ray) radiography systems. High-energy X-ray systems have the advantage of generally better penetration than neutron systems, depending on the material being interrogated. However, neutron systems have the advantage of much better sensitivity to material composition compared to dual high-energy X-ray techniques. In particular, fast neutron radiography offers the potential to discriminate between various classes of organic material, unlike dual energy X-ray techniques that realistically only offer the ability to discriminate between organic and metal objects.

  20. Multiplexed x-ray microcalorimeters with improved energy resolution for Constellation-X

    NASA Astrophysics Data System (ADS)

    Irwin, K. D.; Beall, J. A.; Doriese, W. B.; Duncan, W. D.; Ferreira, L.; Hilton, G. C.; Reintsema, C. D.; Schmidt, D. R.; Ullom, J. N.; Vale, L. R.; Xu, Y.; Zink, B. L.

    2005-12-01

    NIST is working with NASA/Goddard Space Flight Center (GSFC) to develop multiplexed x-ray microcalorimeter arrays optimized for the Constellation-X mission. These arrays are based on superconducting transition-edge sensors (TES) read out with multiplexed superconducting quantum interference device (SQUID) amplifiers. We present recent progress in improving the x-ray energy resolution through engineering the device geometry, and present recent results with 8- and 16-channel multiplexers. In order to achieve the ambitious x-ray energy resolution goals for the Constellation-X microcalorimeters, we have conducted extensive investigations of the high-frequency unexplained noise in TES sensors as a function of operating resistance, current density, applied magnetic field, and device geometry. Using the measured dependencies of the unexplained noise, we have optimized the design of our TES x-ray sensors and achieved FWHM energy resolutions of 2.4 eV at the 5.9 keV Mn Kα complex, which is a significant step towards the Constellation-X resolution goal of 2 eV at 5.9 keV. We also present progress in the development of time-division SQUID multiplexers for the readout of large x-ray calorimeter arrays. We present results from x-ray microcalorimeters in 8- and 16-channel multiplexers. We describe the constraints on the system architecture, and present a practical design for a 32-channel MUX to be used in a kilopixel array. Finally, we have extended this work to develop TES microcalorimeters for higher energy applications, such as the study of Ti emission lines from supernova remnants, including high-resolution velocity diagnostics. We have obtained a spectral resolving power of 4300 (energy / half-energy width) at the 103 keV Gd γ -ray line using a TES with a Sn absorber. We are grateful for technical support from the NASA/GSFC microcalorimeter group, and for financial support from NASA through the Constellation-X program and Grant NDPR S06561-G.

  1. X-ray Emission of Low-Energy-Peaked BL Lacertae Objects

    NASA Astrophysics Data System (ADS)

    Randall, Jill M.; Perlman, Eric S.

    2009-12-01

    Presented here is an analysis of X-ray observations of the following seven low-energy-peaked BL Lacertae objects: BL Lacertae, S5 0716+71, W Comae, 3C 66A, S4 0954+65, OJ 287, and AO 0235+16. The spectral data for these objects were taken from observations by the XMM-Newton and/or Chandra X-ray observatories. These objects are being analyzed in an effort to reanalyze all XMM-Newton and Chandra data of low-energy BL Lacs, similar to the efforts of Perlman et al. [4] for high energy BL Lacs. The objects were studied in an effort to understand the nature of the X-ray and multi-waveband emissions in these objects, study the shape of the spectra, and compare the observations of low-energy-peaked BL Lacs to previous observations of these objects and also to observations of high-energy-peaked BL Lacs. Light curves and spectra were analyzed to look for evidence of spectral variability in the objects and as a comparison to previous research on these objects. Most data shows both synchrotron and Inverse-Compton emission, though only little correlation was seen between the emission strength and the spectral slope. Our data is generally well-fitted to a broken power law model with distinct bimodality seen in the first spectral index (six observations with Γ1~0.4 and four observations with Γ1~3.0), a break in energy between 0.6 and 1.4 keV, and a second spectral index Γ2~2.0. None of the observations showed spectral lines, which is consistent with past results. For S5 0716+71 the XMM-Newton X-ray and optical data, along with radio data obtained from the University of Michigan Radio Astronomy Observatory (UMRAO), a spectral energy distribution was created and peak frequencies were estimated.

  2. A new detector system for low energy X-ray fluorescence coupled with soft X-ray microscopy: First tests and characterization

    NASA Astrophysics Data System (ADS)

    Gianoncelli, Alessandra; Bufon, Jernej; Ahangarianabhari, Mahdi; Altissimo, Matteo; Bellutti, Pierluigi; Bertuccio, Giuseppe; Borghes, Roberto; Carrato, Sergio; Cautero, Giuseppe; Fabiani, Sergio; Giacomini, Gabriele; Giuressi, Dario; Kourousias, George; Menk, Ralf Hendrik; Picciotto, Antonino; Piemonte, Claudio; Rachevski, Alexandre; Rashevskaya, Irina; Stolfa, Andrea; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Zorzi, Nicola

    2016-04-01

    The last decades have witnessed substantial efforts in the development of several detector technologies for X-ray fluorescence (XRF) applications. In spite of the increasing trend towards performing, cost-effective and reliable XRF systems, detectors for soft X-ray spectroscopy still remain a challenge, requiring further study, engineering and customization in order to yield effective and efficient systems. In this paper we report on the development, first characterization and tests of a novel multielement detector system based on low leakage current silicon drift detectors (SDD) coupled to ultra low noise custom CMOS preamplifiers for synchrotron-based low energy XRF. This new system exhibits the potential for improving the count rate by at least an order of magnitude resulting in ten-fold shorter dwell time at an energy resolution similar to that of single element silicon drift detectors.

  3. Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations

    NASA Astrophysics Data System (ADS)

    Fromm, Michel; Boulanouar, Omar

    2016-11-01

    In this paper we present in a first part the latest results of our group which are in relation with the study of DNA damages inflicted by low energy electrons (0-20 eV) in ultra-high vacuum as well as in air under atmospheric conditions. A short description of the drop-casting technique we developed to produce thin and nanometre-scaled DNA layers onto graphite sheets is given. We provide the absolute cross-section for loss of supercoiled topology of plasmid DNA complexed with 1,3-diaminopropane (Dap) in the vacuum under 10 eV electron impact and suggest a specific pathway for the dissociation of the transient negative ion formed by resonant capture of such a low energy electron (LEE) by the DNA's phosphate group when complexed to Dap. Well-gauged DNA-Dap layers with various nanometre-scaled thicknesses are used to evaluate the effective attenuation length of secondary photo-LEEs in the energy range (0-20 eV). The values of 11-16 nm for DNA kept under atmospheric conditions are in good agreement with the rare literature data available and which are stemming from computer simulations. In a second part, we describe the method we have developed in order to expose liquid samples of plasmid DNA to ultra-soft X-rays (Al Kα line at 1.5 keV) under hydroxyl radical scavenging conditions. We provide an experimentally determined percentage of indirect effects in aqueous medium kept under standard conditions of 94.7±2.1% indirect effects; in satisfactory agreement with the data published by others (i.e. 97.7%) relative to gamma irradiation of frozen solutions (Tomita et al., 1995).

  4. Measurements of the spectrum and energy dependence of X-ray transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.

    1978-01-01

    The results of experiments designed to test the theory of X-ray transition radiation and to verify the predicted dependence of the characteristic features of the radiation on the radiator dimensions are presented. The X-ray frequency spectrum produced by 5- to 9-GeV electrons over the range 4 to 30 keV was measured with a calibrated single-crystal Bragg spectrometer, and at frequencies up to 100 keV with an NaI scintillator. The interference pattern in the spectrum and the hardening of the radiation with increasing foil thickness are clearly observed. The energy dependence of the total transition-radiation intensity was studied using a radiator with large dimensions designed to yield energy-dependent signals at very high particle energies, up to E/mc-squared approximately equal to 100,000. The results are in good agreement with the theoretical predictions.

  5. Hard X-ray and low-energy gamma-ray spectrometers

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Crannell, C. J.; Orwig, L. E.; Forrest, D. J.; Lin, R. P.; Starr, R.

    1988-01-01

    Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resoluton for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.

  6. High-energy synchrotron x-ray techniques for studying irradiated materials

    DOE PAGES

    Park, Jun-Sang; Zhang, Xuan; Sharma, Hemant; ...

    2015-03-20

    High performance materials that can withstand radiation, heat, multiaxial stresses, and corrosive environment are necessary for the deployment of advanced nuclear energy systems. Nondestructive in situ experimental techniques utilizing high energy x-rays from synchrotron sources can be an attractive set of tools for engineers and scientists to investigate the structure–processing–property relationship systematically at smaller length scales and help build better material models. In this paper, two unique and interconnected experimental techniques, namely, simultaneous small-angle/wide-angle x-ray scattering (SAXS/WAXS) and far-field high-energy diffraction microscopy (FF-HEDM) are presented. Finally, the changes in material state as Fe-based alloys are heated to high temperatures ormore » subject to irradiation are examined using these techniques.« less

  7. High-energy synchrotron x-ray techniques for studying irradiated materials

    SciTech Connect

    Park, Jun-Sang; Zhang, Xuan; Sharma, Hemant; Kenesei, Peter; Hoelzer, David; Li, Meimei; Almer, Jonathan

    2015-03-20

    High performance materials that can withstand radiation, heat, multiaxial stresses, and corrosive environment are necessary for the deployment of advanced nuclear energy systems. Nondestructive in situ experimental techniques utilizing high energy x-rays from synchrotron sources can be an attractive set of tools for engineers and scientists to investigate the structure–processing–property relationship systematically at smaller length scales and help build better material models. In this paper, two unique and interconnected experimental techniques, namely, simultaneous small-angle/wide-angle x-ray scattering (SAXS/WAXS) and far-field high-energy diffraction microscopy (FF-HEDM) are presented. Finally, the changes in material state as Fe-based alloys are heated to high temperatures or subject to irradiation are examined using these techniques.

  8. Hard X-ray and low-energy gamma-ray spectrometers

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Crannell, C. J.; Orwig, L. E.; Forrest, D. J.; Lin, R. P.; Starr, R.

    1988-01-01

    Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resoluton for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.

  9. Low energy soft x-ray emission spectrometer at BL-09A in NewSUBARU

    SciTech Connect

    Niibe, Masahito; Tokushima, Takashi

    2016-07-27

    A compact soft X-ray emission spectrometer for the energy region of 50-600 eV has been designed and constructed for the long undulator beamline BL-09A in the NewSUBARU synchrotron radiation (SR) facility. The optical design of the spectrometer is based on a grazing incidence flat-field spectrometer using a valid line-spacing grating. The average groove density of the grating is 2000 L/mm, and the angle of incidence to the grating is 86.5 deg. The distances from the slit to the grating and from the grating to the CCD are 355 mm and 650 mm, respectively. The energy resolution, E/ΔE, was estimated to be greater than 1000 in the energy range of 50-600 eV. Spectra of K-emission X-rays of several light elements, such as B, C, N, and O, from various samples were successfully obtained.

  10. Application of a dual energy X-ray imaging method on breast specimen

    NASA Astrophysics Data System (ADS)

    Koukou, V.; Martini, N.; Fountos, G.; Michail, C.; Bakas, A.; Oikonomou, G.; Kandarakis, I.; Nikiforidis, G.

    The purpose of this study was to evaluate a dual energy method, developed by our group, on a breast cancer specimen. A modified radiographic X-ray tube combined with a high resolution complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. A 40/70 kV spectral combination was filtered with 100 μm cadmium (Cd) and 1000 μm copper (Cu) for the low/high-energy combination. Dual energy images were obtained from a formalin-fixed breast cancer specimen for various entrance surface doses (ESD). Initial results showed that the DE images were directly comparable with the mammographic image and similar or even increased calcification information was identified, with mean glandular dose values at acceptable levels.

  11. Model-based x-ray energy spectrum estimation algorithm from CT scanning data with spectrum filter

    NASA Astrophysics Data System (ADS)

    Li, Lei; Wang, Lin-Yuan; Yan, Bin

    2016-10-01

    With the development of technology, the traditional X-ray CT can't meet the modern medical and industry needs for component distinguish and identification. This is due to the inconsistency of X-ray imaging system and reconstruction algorithm. In the current CT systems, X-ray spectrum produced by X-ray source is continuous in energy range determined by tube voltage and energy filter, and the attenuation coefficient of object is varied with the X-ray energy. So the distribution of X-ray energy spectrum plays an important role for beam-hardening correction, dual energy CT image reconstruction or dose calculation. However, due to high ill-condition and ill-posed feature of system equations of transmission measurement data, statistical fluctuations of X ray quantum and noise pollution, it is very hard to get stable and accurate spectrum estimation using existing methods. In this paper, a model-based X-ray energy spectrum estimation method from CT scanning data with energy spectrum filter is proposed. First, transmission measurement data were accurately acquired by CT scan and measurement using phantoms with different energy spectrum filter. Second, a physical meaningful X-ray tube spectrum model was established with weighted gaussian functions and priori information such as continuity of bremsstrahlung and specificity of characteristic emission and estimation information of average attenuation coefficient. The parameter in model was optimized to get the best estimation result for filtered spectrum. Finally, the original energy spectrum was reconstructed from filtered spectrum estimation with filter priori information. Experimental results demonstrate that the stability and accuracy of X ray energy spectrum estimation using the proposed method are improved significantly.

  12. MASS AND ENERGY OF ERUPTING SOLAR PLASMA OBSERVED WITH THE X-RAY TELESCOPE ON HINODE

    SciTech Connect

    Lee, Jin-Yi; Moon, Yong-Jae; Kim, Kap-Sung; Raymond, John C.; Reeves, Katharine K.

    2015-01-10

    We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light coronal mass ejection features are visible in some events. Five events are observed in several passbands in X-rays, which allows for the determination of the eruptive plasma temperature using a filter ratio method. We find that the isothermal temperatures vary from 1.6 to 10 MK. These temperatures are an average weighted toward higher temperature plasma. We determine the mass constraints of eruptive plasmas by assuming simplified geometrical structures of the plasma with isothermal plasma temperatures. This method provides an upper limit to the masses of the observed eruptive plasmas in X-ray passbands since any clumping causes the overestimation of the mass. For the other two events, we assume the temperatures are at the maximum temperature of the X-ray Telescope (XRT) temperature response function, which gives a lower limit of the masses. We find that the masses in XRT, ∼3 × 10{sup 13}-5 × 10{sup 14} g, are smaller in their upper limit than the total masses obtained by LASCO, ∼1 × 10{sup 15} g. In addition, we estimate the radiative loss, thermal conduction, thermal, and kinetic energies of the eruptive plasma in X-rays. For four events, we find that the thermal conduction timescales are much shorter than the duration of eruption. This result implies that additional heating during the eruption may be required to explain the plasma observations in X-rays for the four events.

  13. Solving atomic structures using statistical mechanical searches on x-ray scattering derived potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Wright, Christopher James

    Engineering the next generation of materials, especially nanomaterials, requires a detailed understanding of the material's underlying atomic structure. These structures give us better insight into structure-property relationships, allowing for property driven material design on the atomic level. Even more importantly, understanding structures in-situ will translate stimuli and responses on the macroscopic scale to changes on the nanoscale. Despite the importance of precise atomic structures for materials design, solving atomic structures is difficult both experimentally and computationally. Atomic pair distribution functions (PDFs) provide information on atomic structure, but the difficulty of extracting the PDF from x-ray total scattering measurements limits their use. Translating the PDF into an atomic structure requires the search of a very high dimensional space, the set of all potential atomic configurations. The large computational cost of running these simulations also limits the use of PDF as an atomistic probe. This work aims to address these issues by developing 1) novel statistical mechanical approaches to solving material structures, 2) fast simulation of x-ray total scattering and atomic pair distribution functions (PDFs), and 3) data processing procedures for experimental x-ray total scattering measurements. First, experimentally derived potential energy surfaces (PES) and the statistical mechanical ensembles used to search them are developed. Then the mathematical and computational framework for the PDF and its gradients will be discussed. The combined PDF-PES-ensemble system will be benchmarked against a series of nanoparticle structures to ascertain the efficiency and effectiveness of the system. Experimental data processing procedures, which maximize the usable data, will be presented. Finally, preliminary results from experimental x-ray total scattering measurements will be discussed. This work presents one of the most complete end

  14. Characterization of energy response for photon-counting detectors using x-ray fluorescence

    PubMed Central

    Ding, Huanjun; Cho, Hyo-Min; Barber, William C.; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: To investigate the feasibility of characterizing a Si strip photon-counting detector using x-ray fluorescence. Methods: X-ray fluorescence was generated by using a pencil beam from a tungsten anode x-ray tube with 2 mm Al filtration. Spectra were acquired at 90° from the primary beam direction with an energy-resolved photon-counting detector based on an edge illuminated Si strip detector. The distances from the source to target and the target to detector were approximately 19 and 11 cm, respectively. Four different materials, containing silver (Ag), iodine (I), barium (Ba), and gadolinium (Gd), were placed in small plastic containers with a diameter of approximately 0.7 cm for x-ray fluorescence measurements. Linear regression analysis was performed to derive the gain and offset values for the correlation between the measured fluorescence peak center and the known fluorescence energies. The energy resolutions and charge-sharing fractions were also obtained from analytical fittings of the recorded fluorescence spectra. An analytical model, which employed four parameters that can be determined from the fluorescence calibration, was used to estimate the detector response function. Results: Strong fluorescence signals of all four target materials were recorded with the investigated geometry for the Si strip detector. The average gain and offset of all pixels for detector energy calibration were determined to be 6.95 mV/keV and −66.33 mV, respectively. The detector’s energy resolution remained at approximately 2.7 keV for low energies, and increased slightly at 45 keV. The average charge-sharing fraction was estimated to be 36% within the investigated energy range of 20–45 keV. The simulated detector output based on the proposed response function agreed well with the experimental measurement. Conclusions: The performance of a spectral imaging system using energy-resolved photon-counting detectors is very dependent on the energy calibration of the

  15. Cosmic X-ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, D.; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1985-01-01

    A progress report of research activities carried out in the area of cosmic X-ray physics is presented. The Diffuse X-ray Spectrometer DXS which has been flown twice as a rocket payload is described. The observation times proved to be too small for meaningful X-ray data to be obtained. Data collection and reduction activities from the Ultra-Soft X-ray background (UXT) instrument are described. UXT consists of three mechanically-collimated X-ray gas proportional counters with window/filter combinations which allow measurements in three energy bands, Be (80-110 eV), B (90-187 eV), and O (e84-532 eV). The Be band measurements provide an important constraint on local absorption of X-rays from the hot component of the local interstellar medium. Work has also continued on the development of a calorimetric detector for high-resolution spectroscopy in the 0.1 keV - 8keV energy range.

  16. [The Prediction Algorithm of the Optimal X-Ray Tube Voltage in Variable Energy Imaging].

    PubMed

    Bi, Yan; Chen, Ping; Han, Yan

    2015-03-01

    X-ray variable energy imaging can obtain the sectional information of complicated structural component successively, and get the whole information by multi-spectrum fusion. Now the energy parameters of X ray imaging mainly depend on man-made setting with the certain step voltage. However this modulation doesn't match to the attenuation thickness variation of the object. Therefore, this paper proposes an optimum tube voltage prediction algorithm based on variable energy imaging. It extracts the effective thickness (ET) and near the effective thickness (NET) in the image sequences which are acquired by pre-scanning the detected object. Then it establishes a physical model between image gray, tube voltage and X ray spectrum. And the model of voltage and gray difference between the ET (high quality area) and NET (prediction area) is also established. On the basis of these two models, the optimal imaging energy forecasting model of NET is modeled. Then, solve the model and get the optimal voltage for NET. At last, by the experiment of the steel blocks with different thickness, testify this prediction algorithm. The results compared with the actual values showed that the prediction algorithm can accurately predict 3 or 4 mm at low voltage and 7 or 10 mm at high voltage. Prediction accuracy is over 95%.

  17. X-ray photo-emission and energy dispersive spectroscopy of HA coated titanium

    SciTech Connect

    Drummond, J.L.; Steinberg, A.D.; Krauss, A.R.

    1997-08-01

    The purpose of this study was to determine the chemical composition changes of hydroxyapatite (HA) coated titanium using surface analysis (x-ray photo-emission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls, 30 minutes and 3 hours aged specimens in distilled water or 0.2M sodium phosphate buffer (pH 7.2) at room temperature. Each x-ray photo-emission cycle consisted of 3 scans followed by argon sputtering for 10 minutes for a total of usually 20 cycles, corresponding to a sampling depth of {approximately} 1500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {mu}m area for 500 sec. Scanning electron microscopy examination showed crystal formation (3P{sub 2}O{sub 5}*2CAO*?H{sub 2}O by energy dispersive spectroscopy analysis) on the HA coating for the specimens aged in sodium phosphate buffer. The x-ray photo-emission results indicated the oxidation effect of water on the titanium (as TiO{sub 2}) and the effect of the buffer to increase the surface concentration of phosphorous. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis. The crystal growth was only observed for the sodium phosphate buffer specimens and only on the HA surface.

  18. The soft X-ray diffuse background observed with the HEAO 1 low-energy detectors

    NASA Technical Reports Server (NTRS)

    Garmire, G. P.; Nousek, J. A.; Apparao, K. M. V.; Burrows, D. N.; Fink, R. L.; Kraft, R. P.

    1992-01-01

    Results of a study of the diffuse soft-X-ray background as observed by the low-energy detectors of the A-2 experiment aboard the HEAO 1 satellite are reported. The observed sky intensities are presented as maps of the diffuse X-ray background sky in several energy bands covering the energy range 0.15-2.8 keV. It is found that the soft X-ray diffuse background (SXDB) between 1.5 and 2.8 keV, assuming a power law form with photon number index 1.4, has a normalization constant of 10.5 +/- 1.0 photons/sq cm s sr keV. Below 1.5 keV the spectrum of the SXDB exceeds the extrapolation of this power law. The low-energy excess for the NEP can be fitted with emission from a two-temperature equilibrium plasma model with the temperatures given by log I1 = 6.16 and log T2 = 6.33. It is found that this model is able to account for the spectrum below 1 keV, but fails to yield the observed Galactic latitude variation.

  19. Reanalysis of X-ray emission from M87. 1: The single-phase medium

    NASA Technical Reports Server (NTRS)

    Tsai, John C.

    1994-01-01

    We reanalyze the density and temperature profiles of the X-ray-emitting gas around M87, assuming a spherically symmetric, single-phase model. For given assumed density and temperature profiles, we predict Einstein High Resolution Imager (HRI) and Imaging Proportional Counter (IPC) surface brightness distribution as well as Focal Point Crystal Spectrometer (FPCS) line fluxes, which we compare with the data. We find that a good fit to these data can be obtained and that, with a suitable adjustment of the abundances, the equivalent width of the iron complex at 7 keV as observed by wide-beam instruments can also be explained. In contrast to this, the Einstein Solid State Spectrometer (SSS) spectrum and optically determined mass profiles cannot be accounted for simultaneously with the previous X-ray data. We show that the disagreement of the Solid State Spectrometer with our models is due to an inconsistency of the Solid State Spectrometer data with that of the other X-ray instruments. Because of this, we find no evidence for the existence of absorption above the Galactic value, contrary to an earlier claim based on Solid State Spectrometer data. The disagreement of our models with optical mass data is due either to the assumption of a single-phase model, thus rendering the model unacceptable, or possibly to maximal systematic errors in the FPCS data. We also show that thermal conduction at the Spitzer rate is important in our models, although this conclusion is of limited importance in view of the poor fit of our models to the data.

  20. Search for induced emission from the 178Hfm2 isomer by low-energy x rays

    NASA Astrophysics Data System (ADS)

    Yang, Tian li; Ze, Ren de; Wu, Huai long; Jiang, Tao; He, Yu hui

    2013-07-01

    Whether or not the 178Hfm2 isomer has the characteristic of induced γ emission by low-energy x rays has been a focus of attention for many scientists and researchers in recent decades. In this paper, an experiment regarding triggering 178Hfm2 emission decay is conducted at Shanghai Synchrotron Radiation Facility. An x-ray beam with 20.825-keV energy irradiates a rectangular sample containing about 1011178Hfm2 nuclides. By comparing the net gamma count rates during the irradiation with those after the irradiation, the data show that at the 426-, 495-, and 574-keV gamma lines, there is no significant enhancement, indicating that the induced γ decay of 178Hfm2 has not been observed.

  1. Low energy X-ray grating interferometry at the Brazilian Synchrotron

    NASA Astrophysics Data System (ADS)

    Koch, F. J.; O'Dowd, F. P.; Cardoso, M. B.; Da Silva, R. R.; Cavicchioli, M.; Ribeiro, S. J. L.; Schröter, T. J.; Faisal, A.; Meyer, P.; Kunka, D.; Mohr, J.

    2017-06-01

    Grating based X-ray differential phase contrast imaging has found a large variety of applications in the last decade. Different types of samples call for different imaging energies, and efforts have been made to establish the technique all over the spectrum used for conventional X-ray imaging. Here we present a two-grating interferometer working at 8.3 keV, implemented at the bending magnet source of the IMX beamline of the Brazilian Synchrotron Light Laboratory. The low design energy is made possible by gratings fabricated on polymer substrates, and makes the interferometer mainly suited to the investigation of light and thin samples. We investigate polymer microspheres filled with Fe2O3 nanoparticles, and find that these particles give rise to a significant visibility reduction due to small angle scattering.

  2. Techniques for deriving tissue structure from multiple projection dual-energy x-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Charles, Jr., Harry K. (Inventor); Beck, Thomas J. (Inventor); Feldmesser, Howard S. (Inventor); Magee, Thomas C. (Inventor)

    2004-01-01

    Techniques for deriving bone properties from images generated by a dual-energy x-ray absorptiometry apparatus include receiving first image data having pixels indicating bone mineral density projected at a first angle of a plurality of projection angles. Second image data and third image data are also received. The second image data indicates bone mineral density projected at a different second angle. The third image data indicates bone mineral density projected at a third angle. The third angle is different from the first angle and the second angle. Principal moments of inertia for a bone in the subject are computed based on the first image data, the second image data and the third image data. The techniques allow high-precision, high-resolution dual-energy x-ray attenuation images to be used for computing principal moments of inertia and strength moduli of individual bones, plus risk of injury and changes in risk of injury to a patient.

  3. High-resolution microcalorimeter energy-dispersive spectrometer for x-ray microanalysis and particle analysis

    SciTech Connect

    Wollman, D. A.; Hilton, G. C.; Irwin, K. D.; Dulcie, L. L.; Bergren, N. F.; Martinis, John M.; Newbury, Dale E.; Woo, Keung-Shan; Liu, Benjamin Y. H.; Diebold, Alain C.

    1998-11-24

    We have developed a high-resolution microcalorimeter energy-dispersive spectrometer (EDS) at NIST that provides improved x-ray microanalysis of contaminant particles and defects important to the semiconductor industry. Using our microcalorimeter EDS mounted on a scanning electron microscope (SEM), we have analyzed a variety of specific sized particles on Si wafers, including 0.3 {mu}m diameter W particles and 0.1 {mu}m diameter Al{sub 2}O{sub 3} particles. To compare the particle analysis capabilities of microcalorimeter EDS to that of semiconductor EDS and Auger electron spectroscopy (AES), we report measurements of the Al-K{alpha}/Si-K{alpha} x-ray peak intensity ratio for 0.3 {mu}m diameter Al{sub 2}O{sub 3} particles on Si as a function of electron beam energy. We also demonstrate the capability of microcalorimeter EDS for chemical shift measurements.

  4. Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

    SciTech Connect

    Opachich, Y. P. Huffman, E.; Koch, J. A.; Bell, P. M.; Bradley, D. K.; Hatch, B.; Landen, O. L.; MacPhee, A. G.; Nagel, S. R.; Chen, N.; Gopal, A.; Udin, S.; Feng, J.; Hilsabeck, T. J.

    2016-11-15

    We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1–12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

  5. A high resolution gas scintillation proportional counter for studying low energy cosmic X-ray sources

    NASA Technical Reports Server (NTRS)

    Hamilton, T. T.; Hailey, C. J.; Ku, W. H.-M.; Novick, R.

    1980-01-01

    In recent years much effort has been devoted to the development of large area gas scintillation proportional counters (GSPCs) suitable for use in X-ray astronomy. The paper deals with a low-energy GSPC for use in detecting sub-keV X-rays from cosmic sources. This instrument has a measured energy resolution of 85 eV (FWHM) at 149 eV over a sensitive area of 5 sq cm. The development of imaging capability for this instrument is discussed. Tests are performed on the feasibility of using an arrangement of several phototubes placed adjacent to one another to determine event locations in a large flat counter. A simple prototype has been constructed and successfully operated.

  6. A high resolution gas scintillation proportional counter for studying low energy cosmic X-ray sources

    NASA Technical Reports Server (NTRS)

    Hamilton, T. T.; Hailey, C. J.; Ku, W. H.-M.; Novick, R.

    1980-01-01

    In recent years much effort has been devoted to the development of large area gas scintillation proportional counters (GSPCs) suitable for use in X-ray astronomy. The paper deals with a low-energy GSPC for use in detecting sub-keV X-rays from cosmic sources. This instrument has a measured energy resolution of 85 eV (FWHM) at 149 eV over a sensitive area of 5 sq cm. The development of imaging capability for this instrument is discussed. Tests are performed on the feasibility of using an arrangement of several phototubes placed adjacent to one another to determine event locations in a large flat counter. A simple prototype has been constructed and successfully operated.

  7. Electron cyclotron resonance ion source plasma characterization by energy dispersive x-ray imaging

    NASA Astrophysics Data System (ADS)

    Rácz, R.; Mascali, D.; Biri, S.; Caliri, C.; Castro, G.; Galatà, A.; Gammino, S.; Neri, L.; Pálinkás, J.; Romano, F. P.; Torrisi, G.

    2017-07-01

    Pinhole and CCD based quasi-optical x-ray imaging technique was applied to investigate the plasma of an electron cyclotron resonance ion source (ECRIS). Spectrally integrated and energy resolved images were taken from an axial perspective. The comparison of integrated images taken of argon plasma highlights the structural changes affected by some ECRIS setting parameters, like strength of the axial magnetic confinement, RF frequency and microwave power. Photon counting analysis gives precise intensity distribution of the x-ray emitted by the argon plasma and by the plasma chamber walls. This advanced technique points out that the spatial positions of the electron losses are strongly determined by the kinetic energy of the electrons themselves to be lost and also shows evidences how strongly the plasma distribution is affected by slight changes in the RF frequency.

  8. X-ray tomographic determination of the chemical composition and structure of an inhomogeneous medium

    NASA Astrophysics Data System (ADS)

    Nazarov, V. G.

    2007-08-01

    The chemical composition of an inhomogeneous body consisting of several homogeneous parts is determined by x-ray tomography. At the first stage, an indicator of inhomogeneities is used to determine the internal structure of the body. Next, under certain additional assumptions about the properties of the parts, a method is proposed for partial or complete determination of the chemical composition of each part as based on the results of the previous stage. Mathematically, the problem is reduced to solving the radiative transfer equation and systems of linear algebraic equations. Numerical experiments are performed via computer simulation. The numerical results are illustrated by graphs and tomograms.

  9. Time resolved soft x-ray studies of energy transport in layered and planar laser-driven targets

    SciTech Connect

    Stradling, G.L.

    1982-01-01

    New low-energy x-ray diagnostic techniques are used to explore energy-transport processes in laser heated plasmas. Streak cameras are used for the first time to provide 15-psec time-resolution measurements of sub keV x-ray emission. A very thin (50 ..mu..g/cm/sup 2/) carbon substrate provides a low-energy x-ray window to the transmission photocathode of this soft x-ray streak camera. Active differential vacuum pumping of the instrument is required. X-ray spectral resolution, in the region below 1 keV which includes the spectral peak, is obtained through this initial use of the high-energy cutoff properties of x-ray reflectors with x-ray streak cameras. In this application absorption-edge filters provide spectral channel definition. Enhanced spectral resolution in five sub keV spectral bands, 10-eV wide, are made possible through the use of state-of-the-art metal-multilayer x-ray interference mirrors. These large d-spacing Bragg reflectors, which are synthesized elsewhere, provide great flexibility in sub keV photon energy-band selection and detector geometry. High peak reflectivity (10%) and intermediate bandwidths (10 eV) were obtained in this first low-energy application of these structures. The first use of high-sensitivity, low secondary-electron energy-spread, Csl photocathodes in x-ray streak cameras is also described. Significant increases in sensitivity with only a small and intermittant decrease in dynamic range were observed. The coherent, complementary advances in sub keV, time-resolved x-ray diagnostic capability are applied to energy-transport investigations of 1.06-..mu..m laser plasmas.

  10. Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging.

    PubMed

    Iwanczyk, Jan S; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C; Hartsough, Neal E; Malakhov, Nail; Wessel, Jan C

    2009-01-01

    The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm(2)/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a (57)Co source. An output rate of 6×10(6) counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and

  11. Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

    PubMed Central

    Iwanczyk, Jan S.; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C.; Hartsough, Neal E.; Malakhov, Nail; Wessel, Jan C.

    2009-01-01

    The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a 57Co source. An output rate of 6×106 counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and energy

  12. Scanning electron microscope/energy dispersive x ray analysis of impact residues in LDEF tray clamps

    NASA Technical Reports Server (NTRS)

    Bernhard, Ronald P.; Durin, Christian; Zolensky, Michael E.

    1993-01-01

    Detailed optical scanning of tray clamps is being conducted in the Facility for the Optical Inspection of Large Surfaces at JSC to locate and document impacts as small as 40 microns in diameter. Residues from selected impacts are then being characterized by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis at CNES. Results from this analysis will be the initial step to classifying projectile residues into specific sources.

  13. Use of MCNP code in energy dispersive X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Trojek, T.; Čechák, T.

    2007-10-01

    Monte Carlo simulations enable us to improve the applicability of analytical techniques based on emission of characteristic radiation. In particular, the MCNP4C2 code was tested for interpretation of measured data obtained with the use of energy dispersive X-ray fluorescence analysis. This paper describes MCNP outputs and compares them with the results of analytical calculations or experiments. Then the application of Monte Carlo simulations to the prediction of measurement results is shown, and the MCNP results are verified.

  14. Transient structure in the high-energy X-ray light curve of NP 0532

    NASA Technical Reports Server (NTRS)

    Ryckman, S. G.; Ricker, G. R.; Scheepmaker, A.; Ballintine, J. E.; Doty, J. P.; Downey, P. M.; Lewin, W. H. G.

    1977-01-01

    The paper reports the observation of pulsed fractions in the primary and secondary peaks, as well as in the interpulse region, of the high-energy X-ray light curve of NP 0532. A statistical analysis of light-curve data is performed, and a similar analysis is carried out using simulated data. It is concluded that a previously reported third peak in the light curve was transient in nature.

  15. Analysis of some Nigerian solid mineral ores by energy-dispersive X-ray fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Obiajunwa, E. I.

    2001-11-01

    Determination of major, minor and trace elements in some Nigerian solid mineral ores by energy-dispersive X-ray fluorescence (EDXRF) spectroscopy is described. Concentration values of major, minor and trace elements for Z>18 are reported. The mineral ores studied include (i) tantalite-coloumbite minerals, (ii) bismuth minerals and (iii) lead minerals. The accuracy and precision of the technique for chemical analysis was assured by analysing the geological standards mica-Fe (biotite) and NBS 278 (obsidian).

  16. The High-Energy RXTE X-Ray Spectrum of RX J0852.0-4622

    NASA Astrophysics Data System (ADS)

    Allen, G. E.; Markwardt, C. B.; Petre, R.

    1999-04-01

    A new shell-type supernova remnant, RX J0852.0-4622, was recently discovered in the direction of the Vela remnant. While the Vela remnant dominates the low-energy (ROSAT) X-ray image of this region, the ring of RX J0852.0-4622 is clearly observable at energies > 1.3 keV. This new remnant and the Cas A remnant are the only two sources that have been detected to emit 1.156 MeV gamma rays from the decay of (44) Ti. The presence of (44) Ti, which has a half-life of ~ 90 yr, and the strength of the (44) Ti-line flux indicate that RX J0852.0-4622 is both young ( ~ 600--1100 yr) and close to Earth ( ~ 100--300 pc). Except for the Local Bubble, this remnant may be the closest of the known supernova remnants. A series of scans with the instruments on the RXTE satellite indicate that both the RX J0852.0-4622 and Vela remnants are sources of high-energy X-ray emission. We present the count-rate scan profile and a 3--12 keV RXTE spectrum, which includes emission from both remnants. Although it is difficult to distinguish the RXTE X-ray spectrum of one remnant from the other, spectral models suggest that RX J0852.0-4622 exhibits no evidence of Fe-K--line emission. We discuss whether the high-energy X-ray continuum of this remnant is thermal or non-thermal and review the implications of the results.

  17. Measurement of electron density in dual-energy x-ray CT with monochromatic x rays and evaluation of its accuracy.

    PubMed

    Tsunoo, Takanori; Torikoshi, Masami; Ohno, Yumiko; Uesugi, Kentaro; Yagi, Naoto

    2008-11-01

    Information on electron density is important for radiotherapy treatment planning in order to optimize the dose distribution in the target volume of a patient. At present, the electron density is derived from a computed tomography (CT) number measured in x-ray CT scanning; however, there are uncertainties due to the beam hardening effect and the method by which the electron density is converted from the CT number. In order to measure the electron density with an accuracy of +/-1%, the authors have developed dual-energy x ray CT using monochromatic x rays. They experimentally proved that the measured linear attenuation coefficients were only a few percent lower than the theoretical ones, which led to an accuracy within 2% for the electron density. There were three factors causing inaccuracy in the linear attenuation coefficient and the electron density: the influence of scattered radiation, the nonlinearity in the detector response function, and a theoretical process to derive the electron density from the linear attenuation coefficients. The linear attenuation coefficients of water were experimentally proved to differ by 1%-2% from the theoretical one even when the scattering effect was negligible. The nonlinearity of the response function played an important role in correcting the difference in the linear attenuation coefficient. Furthermore, the theoretical process used for deriving the electron density from the linear attenuation coefficients introduces about 0.6% deviation from the theoretical value into the resultant electron density. This deviation occurs systematically so that it can be corrected. The authors measured the electron densities for seven samples equivalent to soft tissue in dual-energy x-ray CT, and finally obtained them with an accuracy of around +/-1%.

  18. The Application of Monochromatic Energies to Investigate Multiphase Porous Media Systems using Synchrotron X-ray Tomography

    SciTech Connect

    Ham, Kyungmin; Willson, Clinton S.

    2006-01-31

    X-ray computed tomography (CT) is becoming a useful tool for nondestructive imaging of many geoenvironmental and geotechnical systems. Conventional X-ray CT systems typically utilize a polychromatic X-ray beam. While providing a high throughput of photons, the use of polychromatic energy can make quantifying material concentrations, densities or composition very difficult or impossible without appropriate standards. Synchrotron X-rays have an extremely small angular divergence, thus permitting spatial resolution that is only limited by the optical components of the system. In addition, the ability to tune to a monochromatic X-ray energy allows better phase contrast by reducing beam hardening and allowing for elemental discrimination. In this work we will show how monochromatic energy can be used to provide high-quality images allowing for phase separation several different porous media systems thus improving our ability to quantify a range of processes and phenomena.

  19. Study of induced thermoluminescence in CVD diamond film by low-energy X-rays.

    PubMed

    Liu, Chi-Chang; Lin, Jao-Perng; Chu, Tieh-Chi

    2003-07-01

    For diamond film the one-hit model that is used to interpret low-energy X-ray thermoluminescence (TL) will require some modifications. After the films were irradiated with a superficial X-ray machine with different peak voltages, a two-compartment model with three parameters, the target size, the microscopic saturation factor and the high-LET saturation factor, was used to more precisely describe the TL response to X-ray with energies down to 10 kV. The microdosimetric distribution was calculated using single-event Monte Carlo code developed by authors together with EEDL cross-section data library. Some mechanistic insight into the physical aspect of radiation interaction with solid detectors can be obtained. The sensitive size in diamond was found to be about 15 nm. The saturation of one group of sublevels combined with the activation of another group of sublevels caused the relative efficiency to have a local minimum near 20 keV. The relative efficiency becomes higher below 10 keV, which is similar to the increasing relative biological effectiveness when the linear energy transfer passing through a biological system increases. The similarity made this material to be a molecular-scale dosimeter in the future.

  20. HIGH ENERGY, HIGH BRIGHTNESS X-RAYS PRODUCED BY COMPTON BACKSCATTERING AT THE LIVERMORE PLEIADES FACILITY

    SciTech Connect

    Tremaine, A M; Anderson, S G; Betts, S; Crane, J; Gibson, D J; Hartemann, F V; Jacob, J S; Frigola, P; Lim, J; Rosenzweig, J; Travish, G

    2005-05-19

    PLEIADES (Picosecond Laser Electron Interaction for the Dynamic Evaluation of Structures) produces tunable 30-140 keV x-rays with 0.3-5 ps pulse lengths and up to 10{sup 7} photons/pulse by colliding a high brightness electron beam with a high power laser. The electron beam is created by an rf photo-injector system, accelerated by a 120 MeV linac, and focused to 20 {micro}m with novel permanent magnet quadrupoles. To produce Compton back scattered x-rays, the electron bunch is overlapped with a Ti:Sapphire laser that delivers 500 mJ, 100 fs, pulses to the interaction point. K-edge radiography at 115 keV on Uranium has verified the angle correlated energy spectrum inherent in Compton scattering and high-energy tunability of the Livermore source. Current upgrades to the facility will allow laser pumping of targets synchronized to the x-ray source enabling dynamic diffraction and time-resolved studies of high Z materials. Near future plans include extending the radiation energies to >400 keV, allowing for nuclear fluorescence studies of materials.

  1. Characterization of breast calcification types using dual energy x-ray method.

    PubMed

    Martini, N; Koukou, V; Fountos, G; Michail, C; Bakas, A; Kandarakis, I; Speller, R; Nikiforidis, G

    2017-09-15

    Calcifications are products of mineralization whose presence is usually associated with pathological conditions. The minerals mostly seen in several diseases are calcium oxalate (CaC2O4), calcium carbonate (CaCO3) and hydroxyapatite (HAp). Up to date, there is no in vivo method that could discriminate between minerals. To this aim, a dual energy x-ray method was developed in the present study. An analytical model was implemented for the determination of the Calcium/Phosphorus mass ratio ([Formula: see text]). The simulation was carried out using monoenergetic and polyenergetic x-rays and various calcification thicknesses (100-1000 [Formula: see text]) and types (CaC2O4, CaCO3, HAp). The experimental evaluation of the method was performed using the optimized irradiation conditions obtained from the simulation study. X-ray tubes, combined with energy dispersive and energy integrating (imaging) detectors, were used for the determination of the [Formula: see text] in phantoms of different mineral types and thicknesses. Based on the results of the experimental procedure, statistical significant difference was observed between the different types of minerals when calcification thicknesses were 300 [Formula: see text] or higher.

  2. Characterization of breast calcification types using dual energy x-ray method

    NASA Astrophysics Data System (ADS)

    Martini, N.; Koukou, V.; Fountos, G.; Michail, C.; Bakas, A.; Kandarakis, I.; Speller, R.; Nikiforidis, G.

    2017-10-01

    Calcifications are products of mineralization whose presence is usually associated with pathological conditions. The minerals mostly seen in several diseases are calcium oxalate (CaC2O4), calcium carbonate (CaCO3) and hydroxyapatite (HAp). Up to date, there is no in vivo method that could discriminate between minerals. To this aim, a dual energy x-ray method was developed in the present study. An analytical model was implemented for the determination of the Calcium/Phosphorus mass ratio ({{{m}Ca}}/{{{m}P}} ). The simulation was carried out using monoenergetic and polyenergetic x-rays and various calcification thicknesses (100–1000 μ m ) and types (CaC2O4, CaCO3, HAp). The experimental evaluation of the method was performed using the optimized irradiation conditions obtained from the simulation study. X-ray tubes, combined with energy dispersive and energy integrating (imaging) detectors, were used for the determination of the {{{m}Ca}}/{{{m}P}} in phantoms of different mineral types and thicknesses. Based on the results of the experimental procedure, statistical significant difference was observed between the different types of minerals when calcification thicknesses were 300 μ m or higher.

  3. The energy calibration of x-ray absorption spectra using multiple-beam diffraction

    SciTech Connect

    Hagelstein, M.; Cunis, S. ); Frahm, R. ); Rabe, P. )

    1992-01-01

    A new method for calibrating the energy scale of x-ray absorption spectra from an energy dispersive spectrometer has been developed. Distinct features in the diffracted intensity of the curved silicon crystal monochromator have been assigned to multiple-beam diffraction. The photon energies of these structures can be calculated if the precise spacing of the diffracting planes and the orientation of the crystal relative to the incident synchrotron radiation are known. The evaluation of Miller indices of operative reflections and the calculation of the corresponding photon energy is presented. The assignment of operative reflexes is simplified if the monochromator crystal can be rotated around the main diffracting vector {bold H}.

  4. Nonthermal X-ray Spectral Flattening toward Low Energies in Early Impulsive Flares

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2007-01-01

    The determination of the low-energy cutoff to nonthermal electron distributions is critical to the calculation of the nonthermal energy in solar flares. The most direct evidence for low-energy cutoffs is flattening of the power-law, nontherma1 X-ray spectra at low energies. However, because of the plasma preheating often seen in flares, the thermal emissions at low energies may hide such spectral flattening of the nonthermal component. We select a category of flares, which we call "early impulsive flares", in which the > 25 keV hard X-ray (HXR) flux increase is delayed by less than 30 s after the flux increase at lower energies. Thus, the plasma preheating in these flares is minimal, so the nonthermal spectrum can be determined to lower energies than in flares with significant preheating. Out of a sample of 33 early impulsive flares observed by the Ramaty High Energy Solar Spectroscopy Imager (RHESSI), 9 showed spectral flattening toward low energies. In these events, the break energy of the double power-law fit to the HXR spectra lies in the range of 10-50 keV, significantly lower than the value we have seen for other flares that do not show such early impulsive emissions. In particular, it correlates with the HXR flux. After correcting the spatially-integrated spectra for albedo from isotropically emitted X-rays and using RHESSI imaging spectroscopy to exclude the extended albedo halo, we find that albedo associated with isotropic or nearly isotropic electrons can only account for the spectral flattening in 3 flares near Sun center. The spectral flattening in the remaining 6 flares is found to be consistent with the existence of a low-energy cutoff in the electron spectrum, falling in the range of 15-50 keV, which also correlates with the HXR flux.

  5. Energy weighting in grating-based X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Pelzer, Georg; Weber, Thomas; Anton, Gisela; Ballabriga Sune, Rafael; Bayer, Florian; Campbell, Michael; Haas, Wilhelm; Horn, Florian; Llopart Cudie, Xavi; Michel, Norbert; Mollenbauer, Uwe; Rieger, Jens; Ritter, André; Ritter, Ina; Wölfel, Stefan; Wong, Winnie S.; Zang, Andrea; Michel, Thilo

    2014-03-01

    With energy-resolving photon-counting detectors in grating-based x-ray phase-contrast imaging it is possible to reduce the dose needed and optimize the imaging chain towards better performance. The advantage of photon- counting detector's linear energy response and absence of electronic noise in attenuation based imaging is known. The access to the energy information of the photons counted provides even further potential for optimization by applying energy weighting factors. We have evaluated energy weighting for grating-based phase-contrast imaging. Measurements with the hybrid photon-counting detector Dosepix were performed. The concept of energy binning implemented in the pixel electronics allows individual storing of the energy information of the incoming photons in 16 energy bins for each pixel. With this technique the full spectral information can be obtained pixel wise from one single acquisition. On the differential phase-contrast data taken, we applied different types of energy weighting factors. The results presented in this contribution demonstrate the advantages of energy-resolved photon-counting in differential phase-contrast imaging. Using a x-ray spectrum centred significantly above the interferometers design energy leads to poor image quality. But with the proposed method and detector the quality was enhanced by 2.8 times in signal-to-noise ratio squared. As this is proportional to dose, energy- resolved photon-counting might be valuable especially for medical applications.

  6. Dual-energy-X-ray imaging to measure phase volume fractions in a transient multiphase flow

    NASA Astrophysics Data System (ADS)

    Loewen, Eric Paul

    1999-12-01

    The objective of this research was to visualize the pre-mixing phase of a fuel-coolant interaction (FCI) by using combinations of high-speed cinematography and dual energy X-ray imaging to identify and quantify the spatial and temporal characteristics of the three FCI phases---metal (fuel), liquid (coolant water), and voids (generated steam). (1) The high-speed cinematography imaging subsystem and the low-energy X-ray imaging subsystem provided visual photographs and distinguished generated voids from water. (2) The high-energy X-Ray imaging subsystem provided additional discernment of metal from water and vapor. This is the first time that dynamic dual X-ray images have been provided with quantitative results. The data provide new information concerning the melt fractions, melt jet configuration, melt jet velocity, and qualitative spatial and temporal quantification of the pre-mixing event. This information provides new insight into the FCI phenomenon that could not have been deduced from visible-light imaging or other instrumentation such as thermocouples, void sensors, or pressure transmitters. Significant findings include: (1) the fuel column (molten Pb jet) penetrated deeply (<7 cm) into the coolant (water) while maintaining its columnar shape. (2) Energetic FCIs occurred (and were imaged) below the melt-coolant interface temperature equal to the homogenous nucleation temperature (310°C). (3) The molten jet breakup was observed to be caused by hydrodynamic forces. (4) The Pb/water thermal interaction zone was imaged over melt temperatures from 330°C to 640°C and coolant subcooling of 4°C to 80°C. (5) The interface regions between the molten Pb and coolant was observed to grow with decreasing coolant subcooling. This imaging process can be applied to further study of the FCI phenomena at other test facilities. It can also be applied for observation of other two- or three-phase flow phenomena previously opaque to conventional imaging systems.

  7. Modular soft x-ray spectrometer for applications in energy sciences and quantum materials

    NASA Astrophysics Data System (ADS)

    Chuang, Yi-De; Shao, Yu-Cheng; Cruz, Alejandro; Hanzel, Kelly; Brown, Adam; Frano, Alex; Qiao, Ruimin; Smith, Brian; Domning, Edward; Huang, Shih-Wen; Wray, L. Andrew; Lee, Wei-Sheng; Shen, Zhi-Xun; Devereaux, Thomas P.; Chiou, Jaw-Wern; Pong, Way-Faung; Yashchuk, Valeriy V.; Gullikson, Eric; Reininger, Ruben; Yang, Wanli; Guo, Jinghua; Duarte, Robert; Hussain, Zahid

    2017-01-01

    Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer's optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small source (˜1 μ m) and detector pixels (˜5 μ m) with high line density gratings (˜3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNi1/3Co1/3Mn1/3O2 can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

  8. Modular soft x-ray spectrometer for applications in energy sciences and quantum materials.

    PubMed

    Chuang, Yi-De; Shao, Yu-Cheng; Cruz, Alejandro; Hanzel, Kelly; Brown, Adam; Frano, Alex; Qiao, Ruimin; Smith, Brian; Domning, Edward; Huang, Shih-Wen; Wray, L Andrew; Lee, Wei-Sheng; Shen, Zhi-Xun; Devereaux, Thomas P; Chiou, Jaw-Wern; Pong, Way-Faung; Yashchuk, Valeriy V; Gullikson, Eric; Reininger, Ruben; Yang, Wanli; Guo, Jinghua; Duarte, Robert; Hussain, Zahid

    2017-01-01

    Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer's optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small source (∼1μm) and detector pixels (∼5μm) with high line density gratings (∼3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNi1/3Co1/3Mn1/3O2 can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

  9. The Missing Baryon Explorer: A Proposed SMEX Mission to Map the X-ray Emission from the Warm-Hot Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Sanders, W. T.; Missing Baryon Explorer Team

    2003-12-01

    The Missing Baryon Explorer was proposed to NASA in the most recent round of SMEX proposals. It is dedicated to high-resolution x-ray spectroscopy, with medium-resolution x-ray imaging, of the diffuse plasmas in the hot intergalactic medium, the hot Galactic halo, the hot interstellar medium, and from highly-ionized species within the solar system. The highest priority science goal is tracing the structure of the emission from the missing baryonic matter in the local universe, with a secondary science goal of understanding the role of hot material in the in the life cycles of galaxies and stars. To achieve these goals, we propose an imaging x-ray spectrometer, an array of microcalorimeters, to provide 4-eV spectral resolution over the 40 - 2000 eV energy range. A conical-foil optic with a 1.4-meter focal length provides large collecting area and 5-arcminute image quality that matches the spatial resolution of the detectors. Observations are carried out either in pointed mode (first 4 months and after the all-sky survey) or in all-sky survey mode (months 5-10). The final 7 months of the mission combine additional science team pointed observations and guest observer pointings. The Missing Baryon Explorer team includes major hardware contributions from the NASA/Goddard Space Flight Center, Lockheed-Martin, and Spectrum Astro in addition to the University of Wisconsin-Madison. The science team in addition includes members from Yale Univ., SRON, SAO, Princeton Univ., Univ. of Michigan, Univ. of Miami, Johns Hopkins Univ., Carnegie Mellon Univ., California Inst. of Tech., Univ. of California-Berkeley, and Univ. of Alabama-Huntsville.

  10. 'Optical' soft x-ray arrays for fluctuation diagnostics in magnetic fusion energy experiments

    SciTech Connect

    Delgado-Aparicio, L.F.; Stutman, D.; Tritz, K.; Finkenthal, M.; Kaita, R.; Roquemore, L.; Johnson, D.; Majeski, R.

    2004-10-01

    We are developing large pixel count, fast ({>=}100 kHz) and continuously sampling soft x-ray (SXR) array for the diagnosis of magnetohydrodynamics (MHD) and turbulent fluctuations in magnetic fusion energy plasmas. The arrays are based on efficient scintillators, high thoughput multiclad fiber optics, and multichannel light amplification and integration. Compared to conventional x-ray diode arrays, such systems can provide vastly increased spatial coverage, and access to difficult locations with small neutron noise and damage. An eight-channel array has been built using columnar CsI:Tl as an SXR converter and a multianode photomultiplier tube as photoamplifier. The overall system efficiency is measured using laboratory SXR sources, while the time response and signal-to-noise performance have been evaluated by recording MHD activity from the spherical tori (ST) Current Drive Experiment-Upgrade and National Spherical Torus Experiment, both at Princeton Plasma Physics Laboratory.

  11. Residual strain gradient determination in metal matrix composites by synchrotron X-ray energy dispersive diffraction

    NASA Technical Reports Server (NTRS)

    Kuntz, Todd A.; Wadley, Haydn N. G.; Black, David R.

    1993-01-01

    An X-ray technique for the measurement of internal residual strain gradients near the continuous reinforcements of metal matrix composites has been investigated. The technique utilizes high intensity white X-ray radiation from a synchrotron radiation source to obtain energy spectra from small (0.001 cu mm) volumes deep within composite samples. The viability of the technique was tested using a model system with 800 micron Al203 fibers and a commercial purity titanium matrix. Good agreement was observed between the measured residual radial and hoop strain gradients and those estimated from a simple elastic concentric cylinders model. The technique was then used to assess the strains near (SCS-6) silicon carbide fibers in a Ti-14Al-21Nb matrix after consolidation processing. Reasonable agreement between measured and calculated strains was seen provided the probe volume was located 50 microns or more from the fiber/matrix interface.

  12. Crystallographic Characterization of Extraterrestrial Materials by Energy-Scanning X-ray Diffraction

    NASA Technical Reports Server (NTRS)

    Hagiya, Kenji; Mikouchi, Takashi; Ohsumi, Kazumasa; Terada, Yasuko; Yagi, Naoto; Komatsu, Mutsumi; Yamaguchi, Shoki; Hirata, Arashi; Kurokawa, Ayaka; Zolensky, Michael E. (Principal Investigator)

    2016-01-01

    We have continued our long-term project using X-ray diffraction to characterize a wide range of extraterrestrial samples. The stationary sample method with polychromatic X-rays is advantageous because the irradiated area of the sample is always same and fixed, meaning that all diffraction spots occur from the same area of the sample, however, unit cell parameters cannot be directly obtained by this method though they are very important for identification of mineral and for determination of crystal structures. In order to obtain the cell parameters even in the case of the sample stationary method, we apply energy scanning of a micro-beam of monochromatic SR at SPring-8.

  13. Characterization and simulation of linear scintillator arrays for low-energy x-ray detection

    NASA Astrophysics Data System (ADS)

    Franco, L.; Gómez, F.; Badano, A.

    2008-11-01

    Current x-ray imaging in many industrial and medical applications uses different scintillator materials coupled to photodiode arrays. Knowledge of the light distribution and photoelectron signal allows for the improvement of the imaging properties of such devices. We have measured and simulated the pixel scintillation light distribution collected by the photodiode arrays for four commercial scintillator arrays made of cesium iodide, cadmium tungstate and gadolinium oxysulfide with pitches of 0.8 mm and 1.6 mm. We used a collimated low-energy x-ray beam to study the collected signal in each array element and the effective fill factors determined from the photodiode geometry, backing material and radiation transport in the scintillator. A proper description of the optical parameters of these detectors provides excellent agreement of the experimental results with Monte Carlo simulations performed with MANTIS.

  14. High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Shimazoe, K.; Yan, X.; Ueda, O.; Ishikura, T.; Fujiwara, T.; Uesaka, M.; Ohno, M.; Tomita, H.; Yoshihara, Y.; Takahashi, H.

    2016-09-01

    A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

  15. New materials for high-energy-resolution x-ray optics

    DOE PAGES

    Yavas, Hasan; Sutter, John P.; Gog, Thomas; ...

    2017-06-09

    The use of crystals other than silicon for x-ray optics is becoming more common for many challenging experiments such as resonant inelastic x-ray scattering and nuclear resonant scattering. As more—and more specialized—spectrometers become available at many synchrotron radiation facilities, interest in pushing the limits of experimental energy resolution has increased. The potentially large improvements in resolution and efficiency that nonsilicon optics offer are beginning to be realized. Furthermore, this article covers the background and state of the art for nonsilicon crystal optics with a focus on a resolution of 10 meV or better, concentrating on compounds that form trigonal crystals,more » including sapphire, quartz, and lithium niobate, rather than the more conventional cubic materials, including silicon, diamond, and germanium.« less

  16. Fast scattering simulation tool for multi-energy x-ray imaging

    NASA Astrophysics Data System (ADS)

    Sossin, A.; Tabary, J.; Rebuffel, V.; Létang, J. M.; Freud, N.; Verger, L.

    2015-12-01

    A combination of Monte Carlo (MC) and deterministic approaches was employed as a means of creating a simulation tool capable of providing energy resolved x-ray primary and scatter images within a reasonable time interval. Libraries of Sindbad, a previously developed x-ray simulation software, were used in the development. The scatter simulation capabilities of the tool were validated through simulation with the aid of GATE and through experimentation by using a spectrometric CdTe detector. A simple cylindrical phantom with cavities and an aluminum insert was used. Cross-validation with GATE showed good agreement with a global spatial error of 1.5% and a maximum scatter spectrum error of around 6%. Experimental validation also supported the accuracy of the simulations obtained from the developed software with a global spatial error of 1.8% and a maximum error of around 8.5% in the scatter spectra.

  17. Gas Scintillation Proportional Counters for High-Energy X-ray Astronomy

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

    2003-01-01

    A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a balloon-borne hard-x-ray telescope is under development at the Marshall Space Flight Center. These detectors have an active area of approx. 20 sq cm, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approx. 500 microns. The detector s energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Full details of the instrument and its performance will be provided.

  18. High-efficiency high-energy-resolution spectrometer for inelastic X-ray scattering

    NASA Astrophysics Data System (ADS)

    Qian, Q.; Tyson, T. A.; Caliebe, W. A.; Kao, C.-C.

    2005-12-01

    A nine-element analyzer system for inelastic X-ray scattering has been designed and constructed. Each individual analyzer crystal is carefully aligned with an inverse joystick goniometer. For the analyzers silicon wafers with 100 mm diameter are spherically bent to 1 or 0.85 m radius, respectively. Additionally, an analyzer with an extra small radius of 0.182 m and diameter of 100 mm was constructed for X-ray absorption spectroscopy in fluorescence mode. All analyzer crystals with large radius have highly uniform focusing property. The total energy resolution is approximately 0.5 eV at backscattering for the 1 m radius Si(440) analyzer array and approximately 4 eV for the 0.182 m radius Si(440) analyzer at 6493 eV.

  19. Star Factory Near Galactic Center Bathed In High-Energy X-Rays

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Near the crowded core of the Milky Way galaxy, where stars shine so brightly and plentifully that planets there would never experience nighttime, astronomers have found a new phenomenon: a cauldron of 60-million-degree gas enveloping a cluster of young stars. Professor Farhad Zadeh of Northwestern University and his collaborators used NASA's Chandra X-ray Observatory to trace the gas around the Arches cluster, a well-studied region of star formation that is home to some of our Galaxy's largest and youngest stars. "This is the first time we have seen a young cluster of stars surrounded by such a halo of high-energy X-rays," said Zadeh in a press conference at the American Astronomical Society in Pasadena, CA. "This supports theoretical predictions that stellar winds from massive stars can collide with each other and generate very hot gas." Massive stars, newborn stars, and stellar winds have long been known to emit X-rays. The Chandra results are significant because they identify this new type of mechanism of colliding winds to generate X-rays as energetic as those seen in distant starburst galaxies, which are known for their furious pace of star production. The Arches cluster is about 26,000 light years from Earth and only about 1 to 2 million years old. It is also less than 100 light years from what is thought to be a supermassive black hole in the center of our Galaxy. The cluster contains 150 hot, young stars, known as "O" stars, concentrated within a diameter of one light year, making it the most compact cluster known in the Milky Way galaxy. The density of stars makes the region in and around the Arches cluster a microcosm of what is likely occurring in starburst galaxies. "The Arches cluster is one of the best 'local' analogues of starburst galaxies-- the most prodigious stellar nurseries known," said Casey Law of the Harvard-Smithsonian Center for Astrophysics. "Yet the Arches cluster is in our backyard, not millions of light years away." The Arches Cluster

  20. X-Ray

    MedlinePlus

    ... of gray. For some types of X-ray tests, a contrast medium — such as iodine or barium — is introduced into your body to provide greater detail on the images. X-ray technology is used to examine many parts of the ...

  1. X-ray lasers

    SciTech Connect

    Elton, R.C.

    1990-01-01

    This paper provides a source that surveys the fundamentals of x-ray lasers and summarizes recent advances. The author emphasizes x-ray lasers created using high temperature plasmas as the medium. Specific topics discussed included electron-collisional excitation pumping, plasma laser pumping, and gamma-ray lasers. Numerous literature references provided.

  2. Experimental validation of a multi-energy x-ray adapted scatter separation method

    NASA Astrophysics Data System (ADS)

    Sossin, A.; Rebuffel, V.; Tabary, J.; Létang, J. M.; Freud, N.; Verger, L.

    2016-12-01

    Both in radiography and computed tomography (CT), recently emerged energy-resolved x-ray photon counting detectors enable the identification and quantification of individual materials comprising the inspected object. However, the approaches used for these operations require highly accurate x-ray images. The accuracy of the images is severely compromised by the presence of scattered radiation, which leads to a loss of spatial contrast and, more importantly, a bias in radiographic material imaging and artefacts in CT. The aim of the present study was to experimentally evaluate a recently introduced partial attenuation spectral scatter separation approach (PASSSA) adapted for multi-energy imaging. For this purpose, a prototype x-ray system was used. Several radiographic acquisitions of an anthropomorphic thorax phantom were performed. Reference primary images were obtained via the beam-stop (BS) approach. The attenuation images acquired from PASSSA-corrected data showed a substantial increase in local contrast and internal structure contour visibility when compared to uncorrected images. A substantial reduction of scatter induced bias was also achieved. Quantitatively, the developed method proved to be in relatively good agreement with the BS data. The application of the proposed scatter correction technique lowered the initial normalized root-mean-square error (NRMSE) of 45% between the uncorrected total and the reference primary spectral images by a factor of 9, thus reducing it to around 5%.

  3. A synthetic diamond probe for low-energy X-ray dose measurements.

    PubMed

    Assiamah, M; Nam, T L; Keddy, R J

    2007-05-01

    The desirable physical properties of diamond have made the mineral a choice material in radiation measurements. Diamond detectors are currently used extensively in high-energy physics. Their use for low-energy beams such as, for example, in mammography X-ray beams however, has not been fully investigated. This paper describes a diamond probe which has been constructed for the evaluation, as the radiation sensing material, of polycrystalline synthetic diamonds produced by chemical vapour deposition (CVD). The specimens were fabricated in wafer form and so the exposure orientation geometry of the diamond wafers, to give optimum absorption of the incident X-ray beam, was also investigated both experimentally and theoretically. The samples were characterized to obtain information regarding the elemental impurity levels, especially nitrogen, and consequently to establish the material quality. Nitrogen impurities and concentration levels in the diamond lattice have been shown to have a profound effect on the radiation detection properties of diamond. The probe described has the diamond surfaces metallized with titanium, platinum and gold to provide ohmic contacts. The probe was connected independently to both Wellhöfer Dosimetrie (model CU 500) and PTW Unidos E commercial electrometers. In all of the measurements, the incident radiation beam was normal to the edge of the diamond wafer to optimize absorption of the X-ray beam after establishing that this orientation was the optimum geometry. The results of the study are presented in both tabular and graphical forms.

  4. Energy dependent variability and outburst evolution in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Kong, A. K. H.

    2016-12-01

    Almost all low mass black hole X-ray binaries are transient sources. Most of these sources show a certain pattern during outburst: the evolution from low hard state through intermediate state(s) into high soft state and the returning to the hard state at lower luminosity. However, there are outbursts that remain in the hard state (so called "failed" outbursts). Using the technique of covariance spectra we can investigate the variability of individual spectral components on different time scales. Comprehensive studies of covariance spectra for a sample of black hole X-ray binaries observed in the rising low hard state of "normal" outbursts revealed an increase of the covariance ratios towards lower energies that has been interpreted as the sign of additional disc variability on long time scales. There are now two sources (h1743 and gs) that do not show an increase towards lower energies in their covariance ratio. Both sources have been observed during "failed" outbursts and showed photon indices much harder than what is usually observed in black hole X-ray binaries.

  5. Quantitative energy-dispersive x-ray diffraction for identification of counterfeit medicines: a preliminary study

    NASA Astrophysics Data System (ADS)

    Crews, Chiaki C. E.; O'Flynn, Daniel; Sidebottom, Aiden; Speller, Robert D.

    2015-06-01

    The prevalence of counterfeit and substandard medicines has been growing rapidly over the past decade, and fast, nondestructive techniques for their detection are urgently needed to counter this trend. In this study, energy-dispersive X-ray diffraction (EDXRD) combined with chemometrics was assessed for its effectiveness in quantitative analysis of compressed powder mixtures. Although EDXRD produces lower-resolution diffraction patterns than angular-dispersive X-ray diffraction (ADXRD), it is of interest for this application as it carries the advantage of allowing the analysis of tablets within their packaging, due to the higher energy X-rays used. A series of caffeine, paracetamol and microcrystalline cellulose mixtures were prepared with compositions between 0 - 100 weight% in 20 weight% steps (22 samples in total, including a centroid mixture), and were pressed into tablets. EDXRD spectra were collected in triplicate, and a principal component analysis (PCA) separated these into their correct positions in the ternary mixture design. A partial least-squares (PLS) regression model calibrated using this training set was validated using both segmented cross-validation, and with a test set of six samples (mixtures in 8:1:1 and 5⅓:2⅓:2⅓ ratios) - the latter giving a root-mean square error of prediction (RMSEP) of 1.30, 2.25 and 2.03 weight% for caffeine, paracetamol and cellulose respectively. These initial results are promising, with RMSEP values on a par with those reported in the ADXRD literature.

  6. Radiological safety of food irradiation with high energy X-rays: theoretical expectations and experimental evidence

    NASA Astrophysics Data System (ADS)

    Grégoire, O.; Cleland, M. R.; Mittendorfer, J.; Dababneh, S.; Ehlermann, D. A. E.; Fan, X.; Käppeler, F.; Logar, J.; Meissner, J.; Mullier, B.; Stichelbaut, F.; Thayer, D. W.

    2003-06-01

    The radiological safety of red meat irradiated with 7.5 MeV X-rays (bremsstrahlung) has been investigated theoretically and verified by dedicated experiments. Samples of meat and meat ash were located in a large volume of fresh meat at the position of the highest photoneutron fluence and irradiated to an X-ray dose of 15 kGy, twice the maximum dose allowed by the US FDA for meat irradiation. In order to evaluate the safety of treatment with any kind of electron accelerators, two experiments have been performed with different accelerators delivering electrons with a narrow and a broad energy spread. The measured activities and theoretical estimates are of the same order of magnitude. An evaluation of the corresponding radiation exposure from ingestion of the irradiated product has been compared to natural background radiation. The paper concludes that the risk to individuals from intake of food irradiated with X-rays from 7.5 MeV electrons, even with a broad energy spectrum, would be trivial.

  7. Dosimetric evaluation of Rhizophora spp. binderless particleboard phantom for diagnostic X-ray energy

    NASA Astrophysics Data System (ADS)

    Marashdeh, M. W.; Tajuddin, A. A.; Bauk, S.; Hashim, R.

    2017-07-01

    This research aims to evaluate the suitability of using binderless particleboard made from Rhizophora spp. mangrove wood as a dosimetric phantom for X-ray in the diagnostic energy regions. Comparative measurements of percentage depth and surface doses in Rhizophora spp. binderless particleboard phantom and similarly shaped Perspex and water phantoms were performed. Measurements were conducted in the diagnostic X-ray energy range of 50 kVp to 90 kVp. Results showed that the binderless particleboard phantom can be used for dosimetric measurements. For the X-ray beam at 90 kVp, the binderless particleboard and water phantom showed data agreement of 1.6%, 2.7%, and 4.3% at depths of 1, 2, and 4 cm, respectively, whereas the measurements in water and Perspex were 1.8%, 2.7%, and 4.4%. The surface dose differences were due to difference in the backscattering material. The doses measured at the surface were within 0.4% for binderless particleboard and water and within 0.9% for Perspex and water.

  8. Hard X-ray bremsstrahlung production in solar flares by high-energy proton beams

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.; Brown, J. C.

    1985-01-01

    The possibility that solar hard X-ray bremsstrahlung is produced by acceleration of stationary electrons by fast-moving protons, rather than vice versa, as commonly assumed, was investigated. It was found that a beam of protons which involves 1836 times fewer particles, each having an energy 1836 times greater than that of the electrons in the equivalent electron beam model, has exactly the same bremsstrahlung yield for a given target, i.e., the mechanism has an energetic efficiency equal to that of conventional bremsstrahlung models. Allowance for the different degrees of target ionization appropriate to the two models (for conventional flare geometries) makes the proton beam model more efficient than the electron beam model, by a factor of order three. The model places less stringent constraints than a conventional electron beam model on the flare energy release mechanism. It is also consistent with observed X-ray burst spectra, intensities, and directivities. The altitude distribution of hard X-rays predicted by the model agrees with observations only if nonvertical injection of the protons is assumed. The model is inconsistent with gamma-ray data in terms of conventional modeling.

  9. A novel portable energy dispersive X-ray fluorescence spectrometer with triaxial geometry

    NASA Astrophysics Data System (ADS)

    Pessanha, S.; Alves, M.; Sampaio, J. M.; Santos, J. P.; Carvalho, M. L.; Guerra, M.

    2017-01-01

    The X-ray fluorescence technique is a powerful analytical tool with a broad range of applications such as quality control, environmental contamination by heavy metals, cultural heritage, among others. For the first time, a portable energy dispersive X-ray fluorescence spectrometer was assembled, with orthogonal triaxial geometry between the X-ray tube, the secondary target, the sample and the detector. This geometry reduces the background of the measured spectra by reducing significantly the Bremsstrahlung produced in the tube through polarization in the secondary target and in the sample. Consequently, a practically monochromatic excitation energy is obtained. In this way, a better peak-background ratio is obtained compared to similar devices, improving the detection limits and leading to superior sensitivity. The performance of this setup is compared with the one of a benchtop setup with triaxial geometry and a portable setup with planar geometry. Two case studies are presented concerning the analysis of a 18th century paper document, and the bone remains of an individual buried in the early 19th century.

  10. Design of dual energy x-ray detector for conveyor belt with steel wire ropes

    NASA Astrophysics Data System (ADS)

    Dai, Yue; Miao, Changyun; Rong, Feng

    2009-07-01

    A dual energy X-ray detector for conveyor belt with steel wire ropes is researched in the paper. Conveyor belt with steel wire ropes is one of primary transfer equipments in modern production. The traditional test methods like electromagnetic induction principle could not display inner image of steel wire ropes directly. So X-ray detection technology has used to detect the conveyor belt. However the image was not so clear by the interference of the rubber belt. Therefore, the dualenergy X-ray detection technology with subtraction method is developed to numerically remove the rubber belt from radiograph, thus improving the definition of the ropes image. The purpose of this research is to design a dual energy Xray detector that could make the operator easier to found the faulty of the belt. This detection system is composed of Xray source, detector controlled by FPGA chip, PC for running image processing system and so on. With the result of the simulating, this design really improved the capability of the staff to test the conveyor belt.

  11. Determination of high-energy x-ray spectra by photoactivation.

    PubMed

    Nath, R; Schulz, R J

    1976-01-01

    The determination of high-energy x-ray spectra has required scintillation spectrometers with massive shielding, neutron time-of-flight spectrometers, or the tedious counting of electron tracks in nuclear emulsions. A new approach has been developed which takes advantage of the energy dependence of photoactivation cross sections. Radioactivity is produced in a small packet of C, Cu, Co, Y, Zr, and Au foils by approximately 5000 rad (tissue). Since the amount of radioactivity produced in each foil is given by the integral of the product of photonuclear cross section and differential photon fluence, a numerical method for unfolding the spectrum is required, and the orthonormal expansion has been employed for this purpose. The photoactivation method has been used to determine the x-ray spectra produced by 30-MeV electrons incident upon thin and thick tungsten targets, and filtered by equivalent amounts of lead and aluminum. These spectra have been compared to calculated thin-target spectra as well as to those determined by a neutron time-of-flight spectrometer. The central-axis and off-axis x-ray spectra produced by a 33-MeV betatron have also been determined.

  12. High-energy x-ray grating-based phase-contrast radiography of human anatomy

    NASA Astrophysics Data System (ADS)

    Horn, Florian; Hauke, Christian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Seifert, Maria; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

    2016-03-01

    X-ray grating-based phase-contrast Talbot-Lau interferometry is a promising imaging technology that has the potential to raise soft tissue contrast in comparison to conventional attenuation-based imaging. Additionally, it is sensitive to attenuation, refraction and scattering of the radiation and thus provides complementary and otherwise inaccessible information due to the dark-field image, which shows the sub-pixel size granularity of the measured object. Until recent progress the method has been mainly limited to photon energies below 40 keV. Scaling the method to photon energies that are sufficient to pass large and spacious objects represents a challenging task. This is caused by increasing demands regarding the fabrication process of the gratings and the broad spectra that come along with the use of polychromatic X-ray sources operated at high acceleration voltages. We designed a setup that is capable to reach high visibilities in the range from 50 to 120 kV. Therefore, spacious and dense parts of the human body with high attenuation can be measured, such as a human knee. The authors will show investigations on the resulting attenuation, differential phase-contrast and dark-field images. The images experimentally show that X-ray grating-based phase-contrast radiography is feasible with highly absorbing parts of the human body containing massive bones.

  13. Advanced ceramic matrix composites for high energy x-ray generation

    NASA Astrophysics Data System (ADS)

    Khan, Amir Azam; Labbe, Jean Claude

    2011-12-01

    High energy x-ray targets are the anodes used in high performance tubes, designed to work for long operating times and at high power. Such tubes are used in computed tomography (CT) scan machines. Usually the tubes used in CT scanners have to continuously work at high temperatures and for longer scan durations in order to get maximum information during a single scan. These anodes are composed of a refractory substrate which supports a refractory metallic coating. The present work is a review of the development of a ceramic metal composite based on aluminium nitride (AlN) and molybdenum for potential application as the substrate. This composite is surface engineered by coating with tungsten, the most popular material for high energy x-ray targets. To spray metallic coatings on the surface of ceramic matrix composites dc blown arc plasma is employed. The objective is to increase the performance and the life of an x-ray tube. Aluminium nitride-molybdenum ceramic matrix composites were produced by uniaxial hotpressing mixtures of AlN and Mo powders. These composites were characterized for their mechanical, thermal, electrical and micro-structural properties. An optimized composition was selected which contained 25 vol.% of metallic phase dispersed in the AlN matrix. These composites were produced in the actual size of an anode and coated with tungsten through dc blown arc plasma spraying. The results have shown that sintering of large size anodes is possible through uniaxial pressing, using a modified sintering cycle.

  14. Energy calibration of energy-resolved photon-counting pixel detectors using laboratory polychromatic x-ray beams

    NASA Astrophysics Data System (ADS)

    Youn, Hanbean; Han, Jong Chul; Kam, Soohwa; Yun, Seungman; Kim, Ho Kyung

    2014-10-01

    Recently, photon-counting detectors capable of resolving incident x-ray photon energies have been considered for use in spectral x-ray imaging applications. For reliable use of energy-resolved photon-counting detectors (ERPCDs), energy calibration is an essential procedure prior to their use because variations in responses from each pixel of the ERPCD for incident photons, even at the same energy, are inevitable. Energy calibration can be performed using a variety of methods. In all of these methods, the photon spectra with well-defined peak energies are recorded. Every pixel should be calibrated on its own. In this study, we suggest the use of a conventional polychromatic x-ray source (that is typically used in laboratories) for energy calibration. The energy calibration procedure mainly includes the determination of the peak energies in the spectra, flood-field irradiation, determination of peak channels, and determination of calibration curves (i.e., the slopes and intercepts of linear polynomials). We applied a calibration algorithm to a CdTe ERPCD comprised of 128×128 pixels with a pitch of 0.35 mm using highly attenuated polychromatic x-ray beams to reduce the pulse pile-up effect, and to obtain a narrow-shaped spectrum due to beam hardening. The averaged relative error in calibration curves obtained from 16,384 pixels was about 0.56% for 59.6 keV photons from an Americium radioisotope. This pixel-by-pixel energy calibration enhanced the signal- and contrast-to-noise ratios in images, respectively, by a factor of ~5 and 3 due to improvement in image homogeneity, compared to those obtained without energy calibration. One secondary finding of this study was that the x-ray photon spectra obtained using a common algorithm for computing x-ray spectra reasonably described the peaks in the measured spectra, which implies easier peak detection without the direct measurement of spectra using a separate spectrometer. The proposed method will be a useful alternative to

  15. SOLEX: a tunable monochromatic X-ray source in the 1-20 keV energy range for metrology

    NASA Astrophysics Data System (ADS)

    Bonnelle, C.; Jonnard, P.; André, J.-M.; Avila, A.; Laporte, D.; Ringuenet, H.; Lépy, M. C.; Plagnard, J.; Ferreux, L.; Protas, J. C.

    2004-01-01

    A tunable monochromatic X-ray source covering the 1-20 keV energy range is described. The initial X-ray beam is obtained from a dedicated windowless X-ray tube. The energy selection is performed through a cylindrically bent crystal, used either in the reflection (Johann geometry) or in the transmission (Cauchois geometry) mode, by rotating the crystal holder by a 90° angle. Contrary to conventional geometries where the X-ray tube is fixed, here the direction of the exit beam impinging the X-ray detector is fixed. This setup is shown to be useful for various studies: high-resolution spectrometry, characterization of the response function and the efficiency of detectors and optical components, determination of transmission characteristics of different materials. Observations of the Lα line and Kα doublet from a copper anode are presented, that demonstrate the performance of this new setup.

  16. Topics in High-Energy Astrophysics: X-ray Time Lags and Gamma-ray Flares

    NASA Astrophysics Data System (ADS)

    Kroon, John J.

    The Universe is host to a wide variety of high-energy processes that convert gravitational potential energy or rest-mass energy into non-thermal radiation such as bremsstrahlung and synchrotron. Prevailing models of X-ray emission from accreting Black Hole Binaries (BHBs) struggle to simultaneously fit the quiescent X-ray spectrum and the transients which result in the phenomenon known as X-ray time lags. And similarly, classical models of diffusive shock acceleration in pulsar wind nebulae fail to explain the extreme particle acceleration in very short timescales as is inferred from recent gamma-ray flares from the Crab nebula. In this dissertation, I develop new exact analytic models to shed light on these intriguing processes. I take a fresh look at the formation of X-ray time lags in compact sources using a new mathematical approach in which I obtain the exact Green's function solution. The resulting Green's function allows one to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. I obtain the exact solution for the dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous clouds. The model can successfully reproduce both the observed time lags and the quiescent X-ray spectrum using a single set of coronal parameters. I show that the implied coronal radii in the new model are significantly smaller than those obtained in the Monte Carlo simulations, hence greatly reducing the coronal heating problem. Recent bright gamma-ray flares from the Crab nebula observed by AGILE and Fermi reaching GeV energies and lasting several days challenge the contemporary model for particle acceleration in pulsar wind nebulae, specifically the diffusive shock acceleration model. Simulations indicate electron/positron pairs in the Crab nebula pulsar wind must be accelerated up to PeV energies in the presence of ambient magnetic fields with strength B ~100 microG. No

  17. Energy dispersive detector for white beam synchrotron x-ray fluorescence imaging

    SciTech Connect

    Wilson, Matthew D. Seller, Paul; Veale, Matthew C.; Connolley, Thomas; Dolbnya, Igor P.; Malandain, Andrew; Sawhney, Kawal; Grant, Patrick S.; Liotti, Enzo; Lui, Andrew

    2016-07-27

    A novel, “single-shot” fluorescence imaging technique has been demonstrated on the B16 beamline at the Diamond Light Source synchrotron using the HEXITEC energy dispersive imaging detector. A custom made furnace with 200µm thick metal alloy samples was positioned in a white X-ray beam with a hole made in the furnace walls to allow the transmitted beam to be imaged with a conventional X-ray imaging camera consisting of a 500 µm thick single crystal LYSO scintillator, mirror and lens coupled to an AVT Manta G125B CCD sensor. The samples were positioned 45° to the incident beam to enable simultaneous transmission and fluorescence imaging. The HEXITEC detector was positioned at 90° to the sample with a 50 µm pinhole 13 cm from the sample and the detector positioned 2.3m from pinhole. The geometric magnification provided a field of view of 1.1×1.1mm{sup 2} with one of the 80×80 pixels imaging an area equivalent to 13µm{sup 2}. Al-Cu alloys doped with Zr, Ag and Mo were imaged in transmission and fluorescence mode. The fluorescence images showed that the dopant metals could be simultaneously imaged with sufficient counts on all 80x80 pixels within 60 s, with the X-ray flux limiting the fluorescence imaging rate. This technique demonstrated that it is possible to simultaneously image and identify multiple elements on a spatial resolution scale ~10µm or higher without the time consuming need to scan monochromatic energies or raster scan a focused beam of X-rays. Moving to high flux beamlines and using an array of detectors could improve the imaging speed of the technique with element specific imaging estimated to be on a 1 s timescale.

  18. Resolution improvement in x-ray imaging with an energy-resolving detector

    NASA Astrophysics Data System (ADS)

    Persson, Mats; Danielsson, Mats

    2017-03-01

    In x-ray imaging, improving spatial resolution is an important goal, but developing detectors with smaller pixels is technically challenging. We demonstrate a technique for improving the spatial resolution by utilizing the fact that linear attenuation coefficients of all substances within the human body can be expressed, to a good approximation, as a linear combination of two basis functions, or three if there is iodine contrast present in the image. When the x rays pass an interface parallel to the beam direction, the exponential attenuation law makes the linear attenuation coefficient measured by the detector a nonlinear combination of the linear attenuation coefficients on each side of the interface. This so-called nonlinear partial volume effect causes the spectral response to be dependent on the steepness of interfaces in the imaged volume. In this work, we show how this effect can be used to improve the spatial resolution in spectral projection x-ray imaging and quantify the achievable resolution improvement. We simulate x-ray transmission imaging of sharp and gradual changes in the projected path length of iodine contrast with an ideal energy-resolving photon-counting detector and demonstrate that the slope of the transition can be determined from the registered spectrum. We simulate piecewise-linear transitions and show that the algorithm is able to reproduce the transition profile on a subpixel scale. The FWHM resolution of the method is 5-30 % of the pixel width. The results show that an energy-resolving detector can be used to improve spatial resolution when imaging interfaces of highly attenuating objects.

  19. Ultra high energy resolution focusing monochromator for inelastic X-ray scattering spectrometer

    SciTech Connect

    Suvorov, Alexey; Cunsolo, Alessandro; Chubar, Oleg; Cai, Yong Q.

    2015-11-25

    Further development of a focusing monochromator concept for X-ray energy resolution of 0.1 meV and below is presented. Theoretical analysis of several optical layouts based on this concept was supported by numerical simulations performed in the “Synchrotron Radiation Workshop” software package using the physical-optics approach and careful modeling of partially-coherent synchrotron (undulator) radiation. Along with the energy resolution, the spectral shape of the energy resolution function was investigated. We show that under certain conditions the decay of the resolution function tails can be faster than that of the Gaussian function.

  20. Near optimal energy selective x-ray imaging system performance with simple detectors

    SciTech Connect

    Alvarez, Robert E.

    2010-02-15

    Purpose: This article describes a method to achieve near optimal performance with low energy resolution detectors. Tapiovaara and Wagner [Phys. Med. Biol. 30, 519-529 (1985)] showed that an energy selective x-ray system using a broad spectrum source can produce images with a larger signal to noise ratio (SNR) than conventional systems using energy integrating or photon counting detectors. They showed that there is an upper limit to the SNR and that it can be achieved by measuring full spectrum information and then using an optimal energy dependent weighting. Methods: A performance measure is derived by applying statistical detection theory to an abstract vector space of the line integrals of the basis set coefficients of the two function approximation to the x-ray attenuation coefficient. The approach produces optimal results that utilize all the available energy dependent data. The method can be used with any energy selective detector and is applied not only to detectors using pulse height analysis (PHA) but also to a detector that simultaneously measures the total photon number and integrated energy, as discussed by Roessl et al. [Med. Phys. 34, 959-966 (2007)]. A generalization of this detector that improves the performance is introduced. A method is described to compute images with the optimal SNR using projections in a ''whitened'' vector space transformed so the noise is uncorrelated and has unit variance in both coordinates. Material canceled images with optimal SNR can also be computed by projections in this space. Results: The performance measure is validated by showing that it provides the Tapiovaara-Wagner optimal results for a detector with full energy information and also a conventional detector. The performance with different types of detectors is compared to the ideal SNR as a function of x-ray tube voltage and subject thickness. A detector that combines two bin PHA with a simultaneous measurement of integrated photon energy provides near ideal

  1. The Effects of Low- and High-Energy Cutoffs on Solar Flare Microwave and Hard X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Oegerle, William (Technical Monitor)

    2002-01-01

    Microwave and hard x-ray spectra provide crucial information about energetic electrons and their environment in solar flares. These spectra are becoming better determined with the Owens Valley Solar Array (OVSA) and the recent launch of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The proposed Frequency Agile Solar Radiotelescope (FASR) promises even greater advances in radio observations of solar flares. Both microwave and hard x-ray spectra are sensitive to cutoffs in the electron distribution function. The determination of the high-energy cutoff from these spectra establishes the highest electron energies produced by the acceleration mechanism, while determination of the low-energy cutoff is crucial to establishing the total energy in accelerated electrons. This paper will show computations of the effects of both high- and low-energy cutoffs on microwave and hard x-ray spectra. The optically thick portion of a microwave spectrum is enhanced and smoothed by a low-energy cutoff, while a hard x-ray spectrum is flattened below the cutoff energy. A high-energy cutoff steepens the microwave spectrum and increases the wavelength at which the spectrum peaks, while the hard x-ray spectrum begins to steepen at photon energies roughly an order of magnitude below the electron cutoff energy. This work discusses how flare microwave and hard x-ray spectra can be analyzed together to determine these electron cutoff energies. This work is supported in part by the NASA Sun-Earth Connection Program.

  2. The Effects of Low- and High-Energy Cutoffs on Solar Flare Microwave and Hard X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Oegerle, William (Technical Monitor)

    2002-01-01

    Microwave and hard x-ray spectra provide crucial information about energetic electrons and their environment in solar flares. These spectra are becoming better determined with the Owens Valley Solar Array (OVSA) and the recent launch of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The proposed Frequency Agile Solar Radiotelescope (FASR) promises even greater advances in radio observations of solar flares. Both microwave and hard x-ray spectra are sensitive to cutoffs in the electron distribution function. The determination of the high-energy cutoff from these spectra establishes the highest electron energies produced by the acceleration mechanism, while determination of the low-energy cutoff is crucial to establishing the total energy in accelerated electrons. This paper will show computations of the effects of both high- and low-energy cutoffs on microwave and hard x-ray spectra. The optically thick portion of a microwave spectrum is enhanced and smoothed by a low-energy cutoff, while a hard x-ray spectrum is flattened below the cutoff energy. A high-energy cutoff steepens the microwave spectrum and increases the wavelength at which the spectrum peaks, while the hard x-ray spectrum begins to steepen at photon energies roughly an order of magnitude below the electron cutoff energy. This work discusses how flare microwave and hard x-ray spectra can be analyzed together to determine these electron cutoff energies. This work is supported in part by the NASA Sun-Earth Connection Program.

  3. Usefulness of an energy-binned photon-counting x-ray detector for dental panoramic radiographs

    NASA Astrophysics Data System (ADS)

    Fukui, Tatsumasa; Katsumata, Akitoshi; Ogawa, Koichi; Fujiwara, Shuu

    2015-03-01

    A newly developed dental panoramic radiography system is equipped with a photon-counting semiconductor detector. This photon-counting detector acquires transparent X-ray beams by dividing them into several energy bands. We developed a method to identify dental materials in the patient's teeth by means of the X-ray energy analysis of panoramic radiographs. We tested various dental materials including gold alloy, dental amalgam, dental cement, and titanium. The results of this study suggest that X-ray energy scattergram analysis could be used to identify a range of dental materials in a patient's panoramic radiograph.

  4. X-ray spectroscopy studies of nonradiative energy transfer processes in luminescent lanthanide materials

    NASA Astrophysics Data System (ADS)

    Pacold, Joseph I.

    Luminescent materials play important roles in energy sciences, through solid state lighting and possible applications in solar energy utilization, and in biomedical research and applications, such as in immunoassays and fluorescence microscopy. The initial excitation of a luminescent material leads to a sequence of transitions between excited states, ideally ending with the emission of one or more optical-wavelength photons. It is essential to understand the microscopic physics of this excited state cascade in order to rationally design materials with high quantum efficiencies or with other fine-tuning of materials response. While optical-wavelength spectroscopies have unraveled many details of the energy transfer pathways in luminescent materials, significant questions remain open for many lanthanide-based luminescent materials. For organometallic dyes in particular, quantum yields remain limited in comparison with inorganic phosphors. This dissertation reports on a research program of synchrotron x-ray studies of the excited state electronic structure and energy-relaxation cascade in trivalent lanthanide phosphors and dyes. To this end, one of the primary results presented here is the first time-resolved x-ray absorption near edge spectroscopy studies of the transient 4f excited states in lanthanide-activated luminescent dyes and phosphors. This is a new application of time-resolved x-ray absorption spectroscopy that makes it possible to directly observe and, to some extent, quantify intramolecular nonradiative energy transfer processes. We find a transient increase in 4f spectral weight associated with an excited state confined to the 4f shell of trivalent Eu. This result implies that it is necessary to revise the current theoretical understanding of 4f excitation in trivalent lanthanide activators: either transient 4f-5d mixing effects are much stronger than previously considered, or else the lanthanide 4f excited state has an unexpectedly large contribution

  5. X-ray Spectroscopy for Chemical and Energy Sciences. the Case of Heterogeneous Catalysis

    SciTech Connect

    Frenkel, A. I.; van Bokhoven, J. A.

    2014-09-01

    Heterogeneous catalysis is the enabling technology for much of the current and future processes relevant for energy conversion and chemicals synthesis. The development of new materials and processes is greatly helped by the understanding of the catalytic process at the molecular level on the macro/micro-kinetic time scale and on that of the actual bond breaking and bond making. The performance of heterogeneous catalysts is inherently the average over the ensemble of active sites. Much development aims at unravelling the structure of the active site; however, in general, these methods yield the ensemble-average structure. A benefit of X-ray-based methods is the large penetration depth of the X-rays, enabling in situ and operando measurements. Furthermore, the potential of X-ray absorption and emission spectroscopy methods (XANES, EXAFS, HERFD, RIXS and HEROS) to directly measure the structure of the catalytically active site at the single nanoparticle level using nanometer beams at diffraction-limited storage ring sources is highlighted. Use of pump-probe schemes coupled with single-shot experiments will extend the time range from the micro/macro-kinetic time domain to the time scale of bond breaking and making.

  6. X-ray spectroscopy for chemical and energy sciences: the case of heterogeneous catalysis.

    PubMed

    Frenkel, Anatoly I; van Bokhoven, Jeroen A

    2014-09-01

    Heterogeneous catalysis is the enabling technology for much of the current and future processes relevant for energy conversion and chemicals synthesis. The development of new materials and processes is greatly helped by the understanding of the catalytic process at the molecular level on the macro/micro-kinetic time scale and on that of the actual bond breaking and bond making. The performance of heterogeneous catalysts is inherently the average over the ensemble of active sites. Much development aims at unravelling the structure of the active site; however, in general, these methods yield the ensemble-average structure. A benefit of X-ray-based methods is the large penetration depth of the X-rays, enabling in situ and operando measurements. The potential of X-ray absorption and emission spectroscopy methods (XANES, EXAFS, HERFD, RIXS and HEROS) to directly measure the structure of the catalytically active site at the single nanoparticle level using nanometer beams at diffraction-limited storage ring sources is highlighted. The use of pump-probe schemes coupled with single-shot experiments will extend the time range from the micro/macro-kinetic time domain to the time scale of bond breaking and making.

  7. [Application of in situ micro energy dispersive X-ray fluorescence analysis in mineralogy].

    PubMed

    Yang, Hai; Ge, Liang-Quan; Gu, Yi; Zhang, Qing-Xian; Xiong, Sheng-Qing

    2013-11-01

    Thirteen rock samples were collected for studying the variation of element content in the mineral during the alteration process from Xinjiang, China. The IED-6000 in situ micro energy dispersive X-ray fluorescence developed by CDUT was applied to get chemical and physical data from minerals. The non-destructive spectrometer is based on a low-power Mo-anode X-ray tube and a Si-PIN peltier cooled X-ray detector. The unique design of the tube's probe allows very close coupling of polycapillary and makes the use of micro-area measurement feasible and efficient. The spectrometer can be integrated into any microscope for analysis. The long axis diameter of beam spot is about 110 microm. According to micro-EDXRF measurement, the tetrahedrite was corrected to pyrite, improving the efficiency and accuracy of the mineral identification. The feldspar of mineralized rock sample is rich in Cu and Zn which can be used as prospecting indicator elements. Element content of Cr, Mn and Co shows negative correlation with the degree of mineralization.

  8. Identification of inorganic dust particles in bronchoalveolar lavage macrophages by energy dispersive x-ray microanalysis.

    PubMed

    Johnson, N F; Haslam, P L; Dewar, A; Newman-Taylor, A J; Turner-Warwick, M

    1986-01-01

    This study shows that energy dispersive x-ray microprobe analysis to identify and quantify intracellular particles in macrophages obtained by the minimally invasive method of bronchoalveolar lavage (BAL) can detect inorganic dust exposures of many different kinds. Bronchoalveolar lavage macrophages from 22 patients have been examined. Twelve patients had occupational exposure to asbestos, talc, silica, hard metal or printing ink, while 10 had no known history of dust exposure. X-ray microprobe analysis identified particles which related to the known exposures, superimposed on a background of other particles related to smoking (kaolinite and mica) or to the general environment (silicon, titanium, and iron). The particle identification provided useful objective confirmation of the known exposures, except for silica, which could not be distinguished from the general background levels. X-ray microanalysis using BAL macrophages can be helpful for clarification of mixed dust exposures, to identify particles when light microscopy indicates retained dust in patients with no known history of exposure, and to monitor retained particles after removal from exposure.

  9. The UCSD high energy X-ray timing experiment cosmic ray particle anticoincidence detector

    NASA Technical Reports Server (NTRS)

    Hink, P. L.; Rothschild, R. E.; Pelling, M. R.; Macdonald, D. R.; Gruber, D. E.

    1991-01-01

    The HEXTE, part of the X-Ray Timing Explorer (XTE), is designed to make high sensitivity temporal and spectral measurements of X-rays with energies between 15 and 250 keV using NaI/CsI phoswich scintillation counters. To achieve the required sensitivity it is necessary to provide anticoincidence of charged cosmic ray particles incident upon the instrument, some of which interact to produce background X-rays. The proposed cosmic ray particle anticoincidence shield detector for HEXTE uses a novel design based on plastic scintillators and wavelength-shifter bars. It consists of five segments, each with a 7 mm thick plastic scintillator, roughly 50 cm x 50 cm in size, coupled to two wavelength-shifter bars viewed by 1/2 inch photomultiplier tubes. These segments are configured into a five-sided, box-like structure around the main detector system. Results of laboratory testing of a model segment, and calculations of the expected performance of the flight segments and particle anticoincidence detector system are presented to demonstrate that the above anticoincidence detector system satisfies its scientific requirements.

  10. Simulation of X-ray Irradiation on Optics and Chamber Wall Materials for Inertial Fusion Energy

    SciTech Connect

    Reyes, S; Latkowski, J F; Abbott, R P; Stein, W

    2003-09-10

    We have used the ABLATOR code to analyze the effect of the x-ray emission from direct drive targets on the optics and the first wall of a conceptual laser Inertial Fusion Energy (IFE) power plant. For this purpose, the ABLATOR code has been modified to incorporate the predicted x-ray spectrum from a generic direct drive target. We have also introduced elongation calculations in ABLATOR to predict the thermal stresses in the optic and first wall materials. These results have been validated with thermal diffusion calculations, using the LLNL heat transfer and dynamic structural finite element codes Topaz3d and Dyna3d. One of the most relevant upgrades performed in the ABLATOR code consists of the possibility to accommodate multi-material simulations. This new feature allows for a more realistic modeling of typical IFE optics and first wall materials, which may have a number of different layers. Finally, we have used the XAPPER facility, at LLNL, to develop our predictive capability and validate the results. The ABLATOR code will be further modified, as necessary, to predict the effects of x-ray irradiation in both the IFE real case and our experiments on the XAPPER facility.

  11. A high-energy x-ray microscope for inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.; Bennett, G. R.

    1999-01-01

    We have developed a microscope capable of imaging x-ray emission from inertial confinement fusion targets in the range of 7-9 keV. Imaging is accomplished with a Kirkpatrick-Baez type, four-image microscope coated with a WB4C multilayer having a 2d period of 140 Å. This microscope design (a standard used on the University of Rochester's OMEGA laser system) is capable of 5 μm resolution over a region large enough to image an imploded target (˜400 μm). This design is capable of being extended to ˜40 keV if state-of-the-art, short-spacing, multilayer coatings are used (˜25 Å), and has been configured to obtain 3 μm resolution with the appropriate choice of mirror size. As such, this type of microscope could serve as a platform for multiframe, hard x-ray imaging on the National Ignition Facility. Characterization of the microscope and laboratory measurements of the energy response made with a cw x-ray source will be shown.

  12. X-ray spectroscopy for high energy-density X pinch density and temperature measurements (invited)

    SciTech Connect

    Pikuz, S.A.; Shelkovenko, T.A.; Chandler, K.M.; Mitchell, M.D.; Hammer, D.A.; Skobelev, I.Y.; Shlyaptseva, A.S.; Hansen, S.B.

    2004-10-01

    X pinch plasmas produced from fine metal wires can reach near solid densities and temperatures of 1 keV or even more. Plasma conditions change on time scales as short as 5-10 ps as determined using an x-ray streak camera viewing a focusing crystal spectrograph or directly viewing the plasma through multiple filters on a single test. As a result, it is possible to determine plasma conditions from spectra with {approx}10 ps time resolution. Experiments and theory are now coming together to give a consistent picture of the dynamics and kinetics of these high energy density plasmas with very high temporal and spatial precision. A set of diagnostic techniques used in experiments for spectrally, temporally, and spatially resolved measurements of X pinch plasmas is described. Results of plasma parameter determination from these measurements are presented. X ray backlighting of one x-pinch by another with {approx}30 ps x-ray pulses enables the dynamics and kinetics to be correlated in time.

  13. High energy X-ray spectra of cygnus XR-1 observed from OSO-8

    NASA Technical Reports Server (NTRS)

    Dolan, J. F.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.

    1978-01-01

    X-ray spectra of Cygnus XR-1 were measured with the scintillation spectrometer on board the OSO-8 satellite during a period of one and one-half to three weeks in each of the years from 1975 to 1977. Observations were made when the source was both in a high state and in a low state. Typical spectra of the source between 15 and 250 keV are presented. The observed pivoting effect is consistent with two temperature accretion disk models of the X-ray emitting region. No significant break in the spectrum occurred at energies up to 150 keV. The high state as defined in the 3 to 6 keV bandwidth was found to be the higher luminosity state of the X-ray source. One transition from a low to a high state occurred during observations. The time of occurrence of this and other transitions is consistent with the hypothesis that all intensity transitions occur near periastron of the binary system, and that such transitions are caused by changes in the mass transfer rate between the primary and the accretion disk around the secondary.

  14. Internal strain gradients quantified in bone under load using high-energy X-ray scattering.

    PubMed

    Stock, S R; Yuan, Fang; Brinson, L C; Almer, J D

    2011-01-11

    High-energy synchrotron X-ray scattering (>60 keV) allows noninvasive quantification of internal strains within bone. In this proof-of-principle study, wide angle X-ray scattering maps internal strain vs position in cortical bone (murine tibia, bovine femur) under compression, specifically using the response of the mineral phase of carbonated hydroxyapatite. The technique relies on the response of the carbonated hydroxyapatite unit cells and their Debye cones (from nanocrystals correctly oriented for diffraction) to applied stress. Unstressed, the Debye cones produce circular rings on the two-dimensional X-ray detector while applied stress deforms the rings to ellipses centered on the transmitted beam. Ring ellipticity is then converted to strain via standard methods. Strain is measured repeatedly, at each specimen location for each applied stress. Experimental strains from wide angle X-ray scattering and an attached strain gage show bending of the rat tibia and agree qualitatively with results of a simplified finite element model. At their greatest, the apatite-derived strains approach 2500 με on one side of the tibia and are near zero on the other. Strains maps around a hole in the femoral bone block demonstrate the effect of the stress concentrator as loading increased and agree qualitatively with the finite element model. Experimentally, residual strains of approximately 2000 με are present initially, and strain rises to approximately 4500 με at 95 MPa applied stress (about 1000 με above the strain in the surrounding material). The experimental data suggest uneven loading which is reproduced qualitatively with finite element modeling.

  15. Internal strain gradients quantified in bone under load using high-energy X-ray scattering.

    SciTech Connect

    Stock, S.R.; Yuan, F.; Brinson, L.C.; Almer, J.D.

    2011-01-01

    High-energy synchrotron X-ray scattering (>60 keV) allows noninvasive quantification of internal strains within bone. In this proof-of-principle study, wide angle X-ray scattering maps internal strain vs position in cortical bone (murine tibia, bovine femur) under compression, specifically using the response of the mineral phase of carbonated hydroxyapatite. The technique relies on the response of the carbonated hydroxyapatite unit cells and their Debye cones (from nanocrystals correctly oriented for diffraction) to applied stress. Unstressed, the Debye cones produce circular rings on the two-dimensional X-ray detector while applied stress deforms the rings to ellipses centered on the transmitted beam. Ring ellipticity is then converted to strain via standard methods. Strain is measured repeatedly, at each specimen location for each applied stress. Experimental strains from wide angle X-ray scattering and an attached strain gage show bending of the rat tibia and agree qualitatively with results of a simplified finite element model. At their greatest, the apatite-derived strains approach 2500 {micro}{var_epsilon} on one side of the tibia and are near zero on the other. Strains maps around a hole in the femoral bone block demonstrate the effect of the stress concentrator as loading increased and agree qualitatively with the finite element model. Experimentally, residual strains of approximately 2000 {micro}{var_epsilon} are present initially, and strain rises to approximately 4500 {micro}{var_epsilon} at 95 MPa applied stress (about 1000 {micro}{var_epsilon} above the strain in the surrounding material). The experimental data suggest uneven loading which is reproduced qualitatively with finite element modeling.

  16. A computation method of dual-energy x-ray imaging

    NASA Astrophysics Data System (ADS)

    Mou, Xuanqin; Tang, Shaojie; Hong, Wei

    2006-03-01

    Dual-energy X-ray imaging is an important method of medical imaging, capable of not only obtaining spatial information of imaging object but also disclosing its chemical components, and has many applications in clinic. The current computation methods of dual-energy imaging are still based on the model of mono-energy spectrum imaging with some linear calibration, while they are incapable to reflect correctly the physical characteristics of dual-energy imaging and obstruct deeper research in this field. The article presents a new medical X-ray imaging model in accordance with physics of imaging and its corresponding computational method. The computation process includes two steps: first, to compute two attenuation parameters that have clear physical meaning: equivalent electron density and attenuation parameter of photoemission; then to compute the components of high- and low-density mass through a group of simple equation with two variables. Experiments showed that such method has quite a satisfactory precision in theory, that is, the solutions of parameters under different exposure voltages and thickness of tissue for several main tissues of human body are much low in deviations, whose quotient of standard deviation divided by mean are mostly under 0.1%, and at most 0.32%. The method provides not only a new computational way for dual-energy X-ray imaging, but also a feasible analysis for its nature. In addition, the method can be used to linearly rectify data of dual-energy CT and analyze the chemical component of reconstructed object by means of parameters clear in physics.

  17. Estimating photon interaction coefficients from single energy x-ray CT.

    PubMed

    Midgley, S M

    2012-12-07

    Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density N(e) and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are combined with parametric models for the x-ray linear attenuation coefficient μ and energy absorption coefficient μ(en) to predict values at energies 10 keV to 20 MeV. At photon energies employed for CT, the fractional contribution to μ from composition is 0.1-0.4 for soft tissues to bone respectively, and is responsible for strong correlations between HN and N(e). The atomic density of tissues excluding lung is near constant allowing the models to be re-expressed as a function of N(e) alone. The transformed model is subjected to propagation of error analysis and results are presented as the ratio of uncertainties for μ or μ(en) to those for N(e). For soft tissues to bone the ratios are as follows: at photon energies 20-100 keV the ratio is 5.0-2.0, at intermediate energies it is unity and increases above 4 MeV to reach 1.5-2.0 at 20 MeV. Results are discussed in the context of attenuation correction and dosimetry calculations for the same range of photon energies.

  18. Estimating photon interaction coefficients from single energy x-ray CT

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2012-12-01

    Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density Ne and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are combined with parametric models for the x-ray linear attenuation coefficient μ and energy absorption coefficient μen to predict values at energies 10 keV to 20 MeV. At photon energies employed for CT, the fractional contribution to μ from composition is 0.1-0.4 for soft tissues to bone respectively, and is responsible for strong correlations between HN and Ne. The atomic density of tissues excluding lung is near constant allowing the models to be re-expressed as a function of Ne alone. The transformed model is subjected to propagation of error analysis and results are presented as the ratio of uncertainties for μ or μen to those for Ne. For soft tissues to bone the ratios are as follows: at photon energies 20-100 keV the ratio is 5.0-2.0, at intermediate energies it is unity and increases above 4 MeV to reach 1.5-2.0 at 20 MeV. Results are discussed in the context of attenuation correction and dosimetry calculations for the same range of photon energies.

  19. Monte Carlo analysis of energy dependent anisotropy of bremsstrahlung x-ray spectra

    SciTech Connect

    Kakonyi, Robert; Erdelyi, Miklos; Szabo, Gabor

    2009-09-15

    The energy resolved emission angle dependence of x-ray spectra was analyzed by MCNPX (Monte Carlo N particle Monte Carlo) simulator. It was shown that the spectral photon flux had a maximum at a well-defined emission angle due to the anisotropy of the bremsstrahlung process. The higher the relative photon energy, the smaller the emission angle belonging to the maximum was. The trends predicted by the Monte Carlo simulations were experimentally verified. The Monte Carlo results were compared to both the Institute of Physics and Engineering in Medicine spectra table and the SPEKCALCV1.0 code.

  20. Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution

    SciTech Connect

    Andrianov, V. A. Gor'kov, V. P. Koshelets, V. P. Filippenko, L. V.

    2007-02-15

    The effect of the recombination-and edge-related losses of nonequilibrium quasiparticles on the energy resolution of superconducting tunneling detectors is studied. The dependence of the signal on the energy of X-ray photons is measured and the shape of instrument-related lines is studied for the Ti/Nb/Al/AlO{sub x}/Al/Nb/NbN detectors with the Ti/Nb passive electrode. Experimental data are analyzed using the diffusion-based model of tunneling detectors.

  1. Flare onsets in hard and soft X-rays. [magnetic energy conversion in sun

    NASA Technical Reports Server (NTRS)

    Machado, Marcos E.; Orwig, Larry E.; Antonucci, Ester

    1986-01-01

    It is shown that the onset of solar flares, within about 2 min or less before the impulsive peaks, is characterized by an increase in high-energy emission at E less than 100 keV, and strong broadening of soft X-ray lines characteristic of the 10-million-K plasma already present at this stage. The observations are interpreted in terms of the early signature of energy release, during a phase preceding the instability that leads to strong particle acceleration.

  2. Flare onsets in hard and soft X-rays. [magnetic energy conversion in sun

    NASA Technical Reports Server (NTRS)

    Machado, Marcos E.; Orwig, Larry E.; Antonucci, Ester

    1986-01-01

    It is shown that the onset of solar flares, within about 2 min or less before the impulsive peaks, is characterized by an increase in high-energy emission at E less than 100 keV, and strong broadening of soft X-ray lines characteristic of the 10-million-K plasma already present at this stage. The observations are interpreted in terms of the early signature of energy release, during a phase preceding the instability that leads to strong particle acceleration.

  3. K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Serbanescu, Cristina; Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej

    2009-08-01

    K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target, K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source has x-ray conversion efficiency greater than 10-5 into K-alpha line emission. In preparation for phase contrast imaging applications, the size of the resultant K-alpha x-ray emission spot has been also characterized. The source exhibits sufficient spatial coherence to observe phase contrast. We observe a relatively small broadening of the K-alpha source size compared to the size of the laser beam itself. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented.

  4. Measurement of the effective energy of pulsed X-rays emitted from a Mather-type plasma focus device.

    PubMed

    Miremad, Seyed Milad; Shirani Bidabadi, Babak

    2017-07-01

    The current study examined the effective energy of pulsed x-rays emitted from a Mather-type plasma focus device with copper anodes at an energy range of 2-3kJ using x-ray transmission radiography. Aluminum filters of different thicknesses and dental x-ray film were used. When air gas was used at a constant voltage of 21kV at 0.3, 0.6, 0.9 and 1.2 mbar, the effective energy of pulsed the x-ray was 10.9, 10.7, 17.3 and 15.8keV, respectively. At 0.6 mbar of air, as the operating voltage increased to 19, 21 and 23kV, the effective energy of the x-ray radiation was 10.6, 10.7 and 12.4keV, respectively. Comprehensive investigation of the characteristics of x-ray emission from plasma focus devices makes it feasible to use this device as an intensive x-ray generator for medical and industrial purposes. The present study is a part of a program which is planned to realize these applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. On filtration for high-energy phase-contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Riess, Christian; Mohamed, Ashraf; Hinshaw, Waldo; Fahrig, Rebecca

    2015-03-01

    Phase-sensitive x-ray imaging promises unprecedented soft-tissue contrast and resolution. However, several practical challenges have to be overcome when using the setup in a clinical environment. The system design that is currently closest to clinical use is the grating-based Talbot-Lau interferometer (GBI).1-3 The requirements for patient imaging are low patient dose, fast imaging time, and high image quality. For GBI, these requirements can be met most successfully with a narrow energy width, high- ux spectrum. Additionally, to penetrate a human-sized object, the design energy of the system has to be well above 40 keV. To our knowledge, little research has been done so far to investigate optimal GBI filtration at such high x-ray energies. In this paper, we study different filtration strategies and their impact on high-energy GBI. Specifically, we compare copper filtration at low peak voltage with equal-absorption, equal-imaging time K-edge filtration of spectra with higher peak voltage under clinically realistic boundary conditions. We specifically focus on a design energy of 59 keV and investigate combinations of tube current, peak voltage, and filtration that lead to equal patient absorption. Theoretical considerations suggest that the K edge of tantalum might provide a transmission pocket at around 59 keV, yielding a well-shaped spectrum. Although one can observe a slight visibility benefit when using tungsten or tantalum filtration, experimental results indicate that visibility benefits most from a low x-ray tube peak voltage.

  6. Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas

    DOE PAGES

    Maddox, J.; Pablant, N.; Efthimion, P.; ...

    2016-09-07

    Here, soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, n2eZeff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tubemore » under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.« less

  7. Multi-energy x-ray detector calibration for T and impurity density (n) measurements of MCF plasmas.

    PubMed

    Maddox, J; Pablant, N; Efthimion, P; Delgado-Aparicio, L; Hill, K W; Bitter, M; Reinke, M L; Rissi, M; Donath, T; Luethi, B; Stratton, B

    2016-11-01

    Soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne(2)Zeff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.

  8. Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas

    NASA Astrophysics Data System (ADS)

    Maddox, J.; Pablant, N.; Efthimion, P.; Delgado-Aparicio, L.; Hill, K. W.; Bitter, M.; Reinke, M. L.; Rissi, M.; Donath, T.; Luethi, B.; Stratton, B.

    2016-11-01

    Soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne 2 Z eff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.

  9. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering.

    PubMed

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S; Techert, Simone; Strocov, Vladimir N; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-29

    Thermally driven chemistry as well as materials' functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

  10. Electron-Excited X-Ray Microanalysis at Low Beam Energy: Almost Always an Adventure!

    PubMed

    Newbury, Dale E; Ritchie, Nicholas W M

    2016-08-01

    Scanning electron microscopy with energy-dispersive spectrometry has been applied to the analysis of various materials at low-incident beam energies, E 0≤5 keV, using peak fitting and following the measured standards/matrix corrections protocol embedded in the National Institute of Standards and Technology Desktop Spectrum Analyzer-II analytical software engine. Low beam energy analysis provides improved spatial resolution laterally and in-depth. The lower beam energy restricts the atomic shells that can be ionized, reducing the number of X-ray peak families available to the analyst. At E 0=5 keV, all elements of the periodic table except H and He can be measured. As the beam energy is reduced below 5 keV, elements become inaccessible due to lack of excitation of useful characteristic X-ray peaks. The shallow sampling depth of low beam energy microanalysis makes the technique more sensitive to surface compositional modification due to formation of oxides and other reaction layers. Accurate and precise analysis is possible with the use of appropriate standards and by accumulating high count spectra of unknowns and standards (>1 million counts integrated from 0.1 keV to E 0).

  11. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

    NASA Astrophysics Data System (ADS)

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S.; Techert, Simone; Strocov, Vladimir N.; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-01

    Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.

  12. A parameterization scheme for the x-ray linear attenuation coefficient and energy absorption coefficient.

    PubMed

    Midgley, S M

    2004-01-21

    A novel parameterization of x-ray interaction cross-sections is developed, and employed to describe the x-ray linear attenuation coefficient and mass energy absorption coefficient for both elements and mixtures. The new parameterization scheme addresses the Z-dependence of elemental cross-sections (per electron) using a simple function of atomic number, Z. This obviates the need for a complicated mathematical formalism. Energy dependent coefficients describe the Z-direction curvature of the cross-sections. The composition dependent quantities are the electron density and statistical moments describing the elemental distribution. We show that it is possible to describe elemental cross-sections for the entire periodic table and at energies above the K-edge (from 6 keV to 125 MeV), with an accuracy of better than 2% using a parameterization containing not more than five coefficients. For the biologically important elements 1 < or = Z < or = 20, and the energy range 30-150 keV, the parameterization utilizes four coefficients. At higher energies, the parameterization uses fewer coefficients with only two coefficients needed at megavoltage energies.

  13. X-ray Sources by Energy Recovered Linacs and Their Needed R&D

    SciTech Connect

    Benson, Stephen; Douglas, David; Dowell, David; Hernandez-Garcia, Carlos; Kayran, D; Krafft, Geoffrey; Legg, Robert; Moog, E; Obina, T; Rimmer, Robert; Yakimenko, V

    2011-05-01

    In this paper we review the current state of research on energy recovered linacs as drivers for future X-ray sources. For many types of user experiments, such sources may have substantial advantages compared to the workhorse sources of the present: high energy storage rings. Energy recovered linacs need to be improved beyond present experience in both energy and average current to support this application. To build an energy recovered linac based X-ray user facility presents many interesting challenges. We present summaries on the Research and Development (R&D) topics needed for full development of such a source, including the discussion at the Future Light Sources Workshop held in Gaithersburg, Maryland on September 15- 17, 2009. A rst iteration of an R&D plan is presented that is founded on the notion of building a set of succeedingly larger test accelerators exploring cathode physics, high average current injector physics, and beam recirculation and beam energy recovery at high average current. Our basic conclusion is that a reviewable design of such a source can be developed after an R&D period of ve to ten years.

  14. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering

    PubMed Central

    Schreck, Simon; Pietzsch, Annette; Kennedy, Brian; Såthe, Conny; Miedema, Piter S.; Techert, Simone; Strocov, Vladimir N.; Schmitt, Thorsten; Hennies, Franz; Rubensson, Jan-Erik; Föhlisch, Alexander

    2016-01-01

    Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future. PMID:26821751

  15. Common features of particle beams and x-rays generated in a low energy dense plasma focus device

    SciTech Connect

    Behbahani, R. A.; Xiao, C.

    2015-02-15

    Features of energetic charged particle beams and x-ray emission in a low energy (1–2 kJ) plasma focus (DPF) device are described and the possible mechanism are explained based on circuit analyses and energy balance in the DPF system. In particular, the resistance and the voltage across the plasma column are estimated to explain the mechanisms of the generation of particle beams and hard x-ray. The analysis shows that the total inductance of a DPF might have played a role for enhancement of the particle beams and x-ray emissions during the phase of anomalous resistance.

  16. Synchrotron soft X-ray absorption spectroscopy study of carbon and silicon nanostructures for energy applications.

    PubMed

    Zhong, Jun; Zhang, Hui; Sun, Xuhui; Lee, Shuit-Tong

    2014-12-10

    Carbon and silicon materials are two of the most important materials involved in the history of the science and technology development. In the last two decades, C and Si nanoscale materials, e.g., carbon nanotubes, graphene, and silicon nanowires, and quantum dots, have also emerged as the most interesting nanomaterials in nanoscience and nanotechnology for their myriad promising applications such as for electronics, sensors, biotechnology, etc. In particular, carbon and silicon nanostructures are being utilized in energy-related applications such as catalysis, batteries, solar cells, etc., with significant advances. Understanding of the nature of surface and electronic structures of nanostructures plays a key role in the development and improvement of energy conversion and storage nanosystems. Synchrotron soft X-ray absorption spectroscopy (XAS) and related techniques, such as X-ray emission spectroscopy (XES) and scanning transmission X-ray microscopy (STXM), show unique capability in revealing the surface and electronic structures of C and Si nanomaterials. In this review, XAS is demonstrated as a powerful technique for probing chemical bonding, the electronic structure, and the surface chemistry of carbon and silicon nanomaterials, which can greatly enhance the fundamental understanding and also applicability of these nanomaterials in energy applications. The focus is on the unique advantages of XAS as a complementary tool to conventional microscopy and spectroscopy for effectively providing chemical and structural information about carbon and silicon nanostructures. The employment of XAS for in situ, real-time study of property evolution of C and Si nanostructures to elucidate the mechanisms in energy conversion or storage processes is also discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Systematic bias in basis material decomposition applied to quantitative dual-energy x-ray imaging.

    PubMed

    Gingold, E L; Hasegawa, B H

    1992-01-01

    Basis material decomposition represents dual-energy x-ray attenuation measurements in terms of the attenuation coefficients or thickness of two standard materials which, when combined, produce attenuation equivalent to the object being measured. In tomographic imaging, the reconstructed attenuation coefficient is calculated in terms of the attenuation coefficients of the basis materials, while in projection imaging, the thicknesses of two materials can be specified in terms of the basis materials. This analysis shows that basis material decomposition is exact in a dual-monoenergetic system, but for broad spectra, x-ray beam hardening introduces a bias into quantitative measurements. The error is small enough that it can be ignored when dual-energy imaging is used primarily to enhance the contrast of one material over another. The magnitude of the error in quantitative measurements depends on the details of the specific application including the energy of the x-ray beam, and the composition and thickness of the materials included in the object. The magnitude of the error for dual-energy bone densitometry has been analyzed using a first-order propagation of error analysis and the calculations verified by computer simulation. This analysis shows that the magnitude of the systematic error can be as high as 3% for 1 g/cm2 of bone mineral when aluminum and acrylic basis materials are used for the calibration. This systematic error is eliminated when the basis materials are the same as the materials that are being quantified (i.e., bone mineral and water).

  18. Characterization of energy dispersive semiconductor detectors for x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Hopman, Theodore Lambert

    Since the development of the electron microprobe in the 1950s by Castaing, characteristic x-ray emission lines have been used to determine chemical compositions of samples. Energy-dispersive detectors allow simultaneous multi-element analysis; continued improvements in detector technology have lowered limits of detection and allowed the effects of physical processes in the detector to become apparent. A well-characterized detector, in terms of its geometry and its response to x-rays, is essential for accurate and precise chemical analysis. In this work, scans with a collimated 55Fe radionuclide source allowed the geometry of Si(Li) detectors to be determined. Across the surface of the detector the response function was uniform, indicating it is due primarily to detector physics and/or processing electronics. Monochromatized x-rays over an energy range of 1--10 keV were used to generate simple spectra in Si(Li) and silicon drift detectors with analog and digital pulse processing systems. Monte Carlo simulations of detector response allowed approximate contributions from physical processes to be seen individually. Transport of energetic electrons, electron diffusion at metal-semiconductor junctions, and differences in detector structure together determine variation with energy of spectral features. The Si K photoelectron escape step at ˜1.8 keV, previously attributed to electron transport only, is found to be affected by diffusion. The diffusion tail to the low-energy side of the primary peak is found to have a component due to escape of Si L Auger electrons. Escape peak intensities in SDD and Si(Li) detectors agree only when contact photoelectron contributions are taken into account.

  19. Effects of contrast medium on radiation-induced chromosome aberrations. [X-ray; /sup 60/Co

    SciTech Connect

    Matsubara, S.; Suzuki, S.; Suzuki, H.; Kuwabara, Y.; Okano, T.

    1982-07-01

    The effects of contrast material (meglumine iothalamate) on radiation-induced chromosome aberrations were investigated in studies on the lymphocytes of patients who had undergone diagnostic radiography and in vitro experiments with diagnostic x rays and /sup 60/Co ..gamma.. rays. Chromosome and chromatic aberrations were found to increase significantly with increasing concentrations of contrast material that were added at irradiation. However, the aberrations were not associated with elevation of the ratio of dicentric and ring chromosomes to the number of cells with unstable chromosome aberrations at the first mitosis. Lymphocytes irradiated in the absence of contrast material did not show an increase in chromosome-type aberrations when the agent was given in increasing concentrations during subsequent incubation, but there were greater numbers of chromatid gaps and breaks. When lymphocytes were exposed to 400 R (103.2 mC/kg) of /sup 60/Co ..gamma.. rays, the presence of contrast agent did not increase the yield of dicentric and ring chromosomes, but induced a marked delay in cell proliferation, especially in lymphocytes with more heavily damaged chromosomes. In additional examination, the contrast agent itself induced sister chromatid exchanges in lymphocytes.

  20. Energies of GRB blast waves and prompt efficiencies as implied by modelling of X-ray and GeV afterglows

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Duran, Rodolfo Barniol; Piran, Tsvi

    2015-11-01

    We consider a sample of 10 gamma-ray bursts with long-lasting ( ≳ 102 s) emission detected by Fermi/Large Area Telescope and for which X-ray data around 1 d are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average ˜50 times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around 1 d, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: (i) either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow-cooling regime or (ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields (10-6 ≲ ɛB ≲ 10-3) and relatively large isotropic kinetic blast wave energies 10^{53} erg<{E}_{0,kin}<10^{55} erg corresponding to large lower limits on the collimated energies, in the range 10^{52} erg<{E}_{θ ,kin}<5× 10^{52} erg for an ISM (interstellar medium) environment with n ˜ 1 cm-3 and 10^{52} erg<{E}_{θ ,kin}<10^{53} erg for a wind environment with A* ˜ 1. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.

  1. Radio and Hard X-Ray Images of High-Energy Electrons in an X-Class Solar Flare

    NASA Technical Reports Server (NTRS)

    White, S. M.; Krucker, S.; Shibasaki, K.; Yokoyama, T.; Shimojo, M.; Kundu, Mukul R.

    2003-01-01

    We present the first comparison between radio images of high-energy electrons accelerated by a solar flare and images of hard X-rays produced by the same electrons at photon energies above 100 keV. The images indicate that the high-energy X-rays originate at the footpoints of the loops dominating the radio emission. The radio and hard X-ray light curves match each other well and are quantitatively consistent with an origin in a single population of nonthermal electrons with a power-law index of around 4.5-5. The high-frequency radio spectral index suggests a flatter energy spectrum, but this is ruled out by the X-ray spectrum up to 8 MeV.

  2. Radio and Hard X-Ray Images of High-Energy Electrons in an X-Class Solar Flare

    NASA Technical Reports Server (NTRS)

    White, S. M.; Krucker, S.; Shibasaki, K.; Yokoyama, T.; Shimojo, M.; Kundu, Mukul R.

    2003-01-01

    We present the first comparison between radio images of high-energy electrons accelerated by a solar flare and images of hard X-rays produced by the same electrons at photon energies above 100 keV. The images indicate that the high-energy X-rays originate at the footpoints of the loops dominating the radio emission. The radio and hard X-ray light curves match each other well and are quantitatively consistent with an origin in a single population of nonthermal electrons with a power-law index of around 4.5-5. The high-frequency radio spectral index suggests a flatter energy spectrum, but this is ruled out by the X-ray spectrum up to 8 MeV.

  3. Feasibility study for a novel method of dual energy x-ray analysis

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2011-09-01

    Dual energy x-ray analysis (DEXA) is investigated using a nonlinear model for the x-ray linear attenuation coefficient μ that is expressed as a function of electron density Ne and the fourth compositional ratio R4. Nonlinear simultaneous equations are solved using a least-squares algorithm based upon the method of Levenberg and Marquardt. Measurements of μ for low atomic number materials (containing elements hydrogen to calcium) at energies 32-66 keV are used to study DEXA accuracy as a function of sample composition, photon energy and their separation ΔE. Results are presented for ΔE = 5-30 keV, for 2% measurement precision, and the doses involved are quantified. The model is subject to propagation of error analysis and results are presented for the relationship between measurement uncertainties and those for Ne and R4. The analysis shows how DEXA accuracy is controlled by the fractional compositional cross-product, which represents the contribution of composition to μ, and how this can be optimized by careful selection of beam energies according to the compositional range of interest. Accurate DEXA is achieved over restricted energy and compositional ranges: soft tissues only at approximately 15-25 keV, all tissues at approximately 30-80 keV and, for situations where a higher dose can be tolerated, all tissues at approximately 4-8 MeV.

  4. The observed characteristics of flare energy release. II - High-speed soft X-ray fronts

    NASA Technical Reports Server (NTRS)

    Machado, Marcos E.; Xiao, Y. C.; Wu, S. T.; Prokakis, TH.; Dialetis, D.

    1988-01-01

    Flare-associated large-scale brightenings of magnetic loop structures have recently been shown to be related to the propagation of soft X-ray fronts, moving at speeds of the order of 1000 km/s. These are also linked with the brightening of remote H-alpha patches and, in many cases, with type II or U radio emission. A detailed study of the best example found in the Solar Maximum Mission's Hard X-ray Imaging Spectrometer data was performed and with the help of numerical simulations and additional information provided by H-alpha records, it is shown that all together the three energy transport processes proposed by previous authors, namely high-energy particles, conduction fronts, and shocks, play significant roles in the redistribution of flare energy within the loops. The observable evidence of thermal flux limitation and the implication of these and previous results on the efficiency ratio between thermal and nonthermal processes in flares are discussed. Finally, these results are placed under the perspective of the interacting loop model of flares discussed in previous papers, to show that only about 10 percent of the total energy conversion occurs at the interface between loops. The bulk of the flare energy seems to be released internally within one of the bipolar loop structures.

  5. The observed characteristics of flare energy release. II - High-speed soft X-ray fronts

    NASA Technical Reports Server (NTRS)

    Machado, Marcos E.; Xiao, Y. C.; Wu, S. T.; Prokakis, TH.; Dialetis, D.

    1988-01-01

    Flare-associated large-scale brightenings of magnetic loop structures have recently been shown to be related to the propagation of soft X-ray fronts, moving at speeds of the order of 1000 km/s. These are also linked with the brightening of remote H-alpha patches and, in many cases, with type II or U radio emission. A detailed study of the best example found in the Solar Maximum Mission's Hard X-ray Imaging Spectrometer data was performed and with the help of numerical simulations and additional information provided by H-alpha records, it is shown that all together the three energy transport processes proposed by previous authors, namely high-energy particles, conduction fronts, and shocks, play significant roles in the redistribution of flare energy within the loops. The observable evidence of thermal flux limitation and the implication of these and previous results on the efficiency ratio between thermal and nonthermal processes in flares are discussed. Finally, these results are placed under the perspective of the interacting loop model of flares discussed in previous papers, to show that only about 10 percent of the total energy conversion occurs at the interface between loops. The bulk of the flare energy seems to be released internally within one of the bipolar loop structures.

  6. SU-C-18C-03: Dual-Energy X-Ray Fluoroscopy Imaging System

    SciTech Connect

    Virshup, G; Richmond, M; Mostafavi, H; Ganguly, A; Fu, D

    2014-06-01

    Purpose: This work studies the clinical utility of dual energy (DE) subtraction fluoroscopy for fiducial-free tumor tracking in lung radiation therapy (RT). Improvement in tumor visualization and quantification of tumor shift within a breathing cycle were analyzed. Methods: Twenty subjects who were undergoing RT for lung cancer were recruited following institutional review board approval. The subjects had a range of tumor sizes, locations in the lungs, and body sizes. An x-ray imaging system was setup with the following components: (a) x-ray tube (Varian G-242, Varian Medical Systems (VMS), CA) (b) flat panel detector (4030CB, VMS, CA) and (c) x-ray generator (EPS 50RF, EMD, Canada). Firmware and software modifications were made to the generator to allow 10 x-ray pulse pairs with alternating low/high kV, 100 ms apart for ∼4s (one breathing cycle). Images were obtained at 4 angles: 0°, 45°, 90° and 135°. Weighted subtraction of a kV-pair image set was used to create a “bone-free” image of the lungs. The 2D tumor-shift in each subtracted image and the 3D shift during a breathing cycle was calculated using all views. Results: The subjects enrolled had the following statistics: average age 62.3±7.1 years, 5 female/15 male, 11 had tumors on the right and 9 on the left and the average tumor size was ∼31.4±10.8 mm. X-ray imaging conditions for the pulse pairs were: 70/120 kVp, 280/221 mA and 65/8 ms. For views where these parameters were insufficient 80/130 kVp, 280/221 mA and 60/12 ms was used. Tumor visibility improved for 0°, 45°, 90° and 135° in 100%, 55%, 75% and 80% of the cases respectively. Tumor shift during a breathing cycle was: 2.4±1.0 mm AP, 2.7±1.4 mm LR and 7.6±4.8 mm IS. Conclusion: DE subtraction fluoroscopy allowed improved visualization and quantification of movement of tumors in the lungs during a breathing cycle. This study was entirely funded by Varian Medical Systems.

  7. Formation, disruption and energy output of Population III X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ryu, Taeho; Tanaka, Takamitsu L.; Perna, Rosalba

    2016-02-01

    The first astrophysical objects shaped the cosmic environment by reionizing and heating the intergalactic medium (IGM). Particularly, X-rays are very efficient at heating the IGM before reionization is complete. High-mass X-ray binaries (HMXBs) in early stellar populations are prime candidates for driving the thermal evolution of the IGM at redshifts z ≳ 20; however, their formation efficiency is not well understood. Using N-body simulations, we estimate the HMXB formation rate via mutual gravitational interactions of nascent, small groups of the Population III stars. We run two sets of calculations: (i) stars formed in small groups of five in nearly Keplerian initial orbits and (ii) collision of two such groups (an expected outcome of mergers of host protogalaxies). We find that HMXBs form at a rate of one per ≳ 104 M⊙ in newly born stars, and that they emit with a power of ˜1041 erg s-1 in the 2-10 keV band per star formation rate. This value is a factor of ˜102 larger than what is observed in star-forming galaxies at lower redshifts; the X-ray production from early HMXBs would have been even more copious, if they also formed in situ or via migration in protostellar discs. Combining our results with earlier studies suggests that early HMXBs were highly effective at heating the IGM and leaving a strong 21-cm signature. We discuss broader implications of our results, such as the rate of long gamma-ray bursts from Population III stars and the direct collapse channel for massive black hole formation.

  8. NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A{sup *} flares

    SciTech Connect

    Barrière, Nicolas M.; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Zoglauer, Andreas; Baganoff, Frederick K.; Christensen, Finn E.; Dexter, Jason; Grefenstette, Brian; Harrison, Fiona A.; Madsen, Kristin K.; Hailey, Charles J.; Mori, Kaya; Zhang, Shuo; Stern, Daniel; Zhang, William W.

    2014-05-01

    Sagittarius A{sup *} harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A{sup *} spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A{sup *} X-ray flares extends to high energy, with no evidence for a cutoff. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (∼55 times quiescence in the 2-10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse Compton models. One flare exhibits large and rapid (<100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within ∼10 Schwarzschild radii of the black hole.

  9. NuSTAR Detection of High-Energy X-Ray Emission and Rapid Variability from Sagittarius A(star) Flares

    NASA Technical Reports Server (NTRS)

    Barriere, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Dexter, Jason; Grefenstette, Brian; Hailey, Charles J.; Zhang, William W.

    2014-01-01

    Sagittarius A(star) harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A(star) spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A(star) X-ray flares extends to high energy, with no evidence for a cut off. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (approx. 55 times quiescence in the 2- 10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse-Compton models. One flare exhibits large and rapid (less than 100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within approx. 10 Schwarzschild radii of the black hole.

  10. Dual-Source Multi-Energy CT with Triple or Quadruple X-ray Beams.

    PubMed

    Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H

    2016-02-01

    Energy-resolved photon-counting CT (PCCT) is promising for material decomposition with multi-contrast agents. However, corrections for non-idealities of PCCT detectors are required, which are still active research areas. In addition, PCCT is associated with very high cost due to lack of mass production. In this work, we proposed an alternative approach to performing multi-energy CT, which was achieved by acquiring triple or quadruple x-ray beam measurements on a dual-source CT scanner. This strategy was based on a "Twin Beam" design on a single-source scanner for dual-energy CT. Examples of beam filters and spectra for triple and quadruple x-ray beam were provided. Computer simulation studies were performed to evaluate the accuracy of material decomposition for multi-contrast mixtures using a tri-beam configuration. The proposed strategy can be readily implemented on a dual-source scanner, which may allow material decomposition of multi-contrast agents to be performed on clinical CT scanners with energy-integrating detector.

  11. Dual-Source Multi-Energy CT with Triple or Quadruple X-ray Beams

    PubMed Central

    Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H.

    2016-01-01

    Energy-resolved photon-counting CT (PCCT) is promising for material decomposition with multi-contrast agents. However, corrections for non-idealities of PCCT detectors are required, which are still active research areas. In addition, PCCT is associated with very high cost due to lack of mass production. In this work, we proposed an alternative approach to performing multi-energy CT, which was achieved by acquiring triple or quadruple x-ray beam measurements on a dual-source CT scanner. This strategy was based on a “Twin Beam” design on a single-source scanner for dual-energy CT. Examples of beam filters and spectra for triple and quadruple x-ray beam were provided. Computer simulation studies were performed to evaluate the accuracy of material decomposition for multi-contrast mixtures using a tri-beam configuration. The proposed strategy can be readily implemented on a dual-source scanner, which may allow material decomposition of multi-contrast agents to be performed on clinical CT scanners with energy-integrating detector. PMID:27330237

  12. Analysis of Fast Electron Energy Distribution by Measuring Hard X-ray Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Daykin, Tyler; Sawada, Hiroshi; Sentoku, Yasuhiko; Bass, Anthony; Griffin, Brandon; Pandit, Rishi; Beg, Farhat; Chen, Hui; McLean, Harry; Link, Anthony; Patel, Prav; Ping, Yuan

    2015-11-01

    Characterization of intense, short-pulse laser-produced fast electrons is important for fundamental understanding and applications. We carried out an experiment to characterize the fast electron energy distribution by measuring angular-dependent high-energy bremsstrahlung x-rays. A 100 μm thick metal foil (Al, Cu, and Ag) mounted on a plastic backing was irradiated by the 0.35 ps, 15 J Leopard Laser at the Nevada Terawatt Facility. The bremsstrahlung x-rays and the escaping electrons from the target were recorded using differential filter stack spectrometers at 22° and 45° off laser axis and a magnet-based electron spectrometer along the laser axis. The electron spectrum inferred from two different diagnostics had single slope temperature of ~ 1.5 MeV for the Cu foil. The results were compared to an analytic calculation and a 2-D Particle-in-cell code, PICLS. The analysis of the electron energy distribution and angular distribution will be presented. This work was supported by the UNR Office of the Provost and by DOE/OFES under Contract No. DE-SC0008827. This collaborative work was partially supported under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Con.

  13. Dual-source multi-energy CT with triple or quadruple x-ray beams

    NASA Astrophysics Data System (ADS)

    Yu, Lifeng; Li, Zhoubo; Leng, Shuai; McCollough, Cynthia H.

    2016-03-01

    Energy-resolved photon-counting CT (PCCT) is promising for material decomposition with multi-contrast agents. However, corrections for non-idealities of PCCT detectors are required, which are still active research areas. In addition, PCCT is associated with very high cost due to lack of mass production. In this work, we proposed an alternative approach to performing multi-energy CT, which was achieved by acquiring triple or quadruple x-ray beam measurements on a dual-source CT scanner. This strategy was based on a "Twin Beam" design on a single-source scanner for dual-energy CT. Examples of beam filters and spectra for triple and quadruple x-ray beam were provided. Computer simulation studies were performed to evaluate the accuracy of material decomposition for multi-contrast mixtures using both tri-beam and quadruple-beam configurations. The proposed strategy can be readily implemented on a dual-source scanner, which may allow material decomposition of multi-contrast agents to be performed on clinical CT scanners with energy-integrating detector.

  14. [Application of the racial algorithm in energy dispersive X-ray fluorescence overlapped spectrum analysis].

    PubMed

    Zeng, Guo-Qiang; Luo, Yao-Yao; Ge, Liang-Quan; Zhang, Qing-Xian; Gu, Yi; Cheng, Feng

    2014-02-01

    In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis can't be carried out because we can't recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in +/- 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis.

  15. Determination of selenium in biological samples with an energy-dispersive X-ray fluorescence spectrometer.

    PubMed

    Li, Xiaoli; Yu, Zhaoshui

    2016-05-01

    Selenium is both a nutrient and a toxin. Selenium-especially organic selenium-is a core component of human nutrition. Thus, it is very important to measure selenium in biological samples. The limited sensitivity of conventional XRF hampers its widespread use in biological samples. Here, we describe the use of high-energy (100kV, 600W) linearly polarized beam energy-dispersive X-Ray fluorescence spectroscopy (EDXRF) in tandem with a three-dimensional optics design to determine 0.1-5.1μgg(-1) levels of selenium in biological samples. The effects of various experimental parameters such as applied voltage, acquisition time, secondary target and various filters were thoroughly investigated. The detection limit of selenium in biological samples via high-energy (100kV, 600W) linearly polarized beam energy-dispersive X-ray fluorescence spectroscopy was decreased by one order of magnitude versus conventional XRF (Paltridge et al., 2012) and found to be 0.1μg/g. To the best of our knowledge, this is the first report to describe EDXRF measurements of Se in biological samples with important implications for the nutrition and analytical chemistry communities.

  16. Extension to Low Energies (<7keV) of High Pressure X-Ray Absorption Spectroscopy

    SciTech Connect

    Itie, J.-P.; Flank, A.-M.; Lagarde, P.; Idir, M.; Polian, A.; Couzinet, B.

    2007-01-19

    High pressure x-ray absorption has been performed down to 3.6 keV, thanks to the new LUCIA beamline (SLS, PSI) and to the use of perforated diamonds or Be gasket. Various experimental geometries are proposed, depending on the energy of the edge and on the concentration of the studied element. A few examples will be presented: BaTiO3 at the titanium K edge, Zn0.95 Mn0.05O at the manganese K edge, KCl at the potassium K edge.

  17. Bone geometry, structure and mineral distribution using Dual energy X ray Absorptiometry (DXA)

    NASA Technical Reports Server (NTRS)

    Whalen, Robert; Cleek, Tammy

    1993-01-01

    Dual energy x-ray absorptiometry (DXA) is currently the most widely used method of analyzing regional and whole body changes in bone mineral content (BMC) and areal (g/sq cm) bone mineral density (BMD). However, BMC and BMD do not provide direct measures of long bone geometry, structure, or strength nor do regional measurements detect localized changes in other regions of the same bone. The capabilities of DXA can be enhanced significantly by special processing of pixel BMC data which yields cross-sectional geometric and structural information. We have extended this method of analysis in order to develop non-uniform structural beam models of long bones.