Polarization of coherent synchrotron radiation from an electron beam rotating in a plasma

After eliminating reflections from the walls of the plasma container, we observed polarization of the coherent synchrotron radiation from a relativistic electron beam rotating in a plasma. Several features of the polarization agree well with calculations based on the single particle synchrotron radiation theory. A particular polarization ratio (Fig. 3) does not, however. We deduce from this direct diffraction of the radiation by the beam electrons. This is strong evidence for beam-particle bunches of size cm. Also, there must be some absorption of the extraordinary wave to account for the observations. We suggest a way to apply these results to measure the pitch angle of the beam.Work supported by Army Research Office.     

Highlights of synchrotron radiation

The applications of the electromagnetic radiation generated by relativistic electrons circulating in synchrotrons and storage rings have rapidly extended into many scientific disciplines. This article first briefly reviews the history of synchrotron radiation, and recapitulates its properties. The available sources are listed, and some aspects of the facilities that are required to make use of the radiation are discussed, with particular emphasis on the optical elements. Several noteworthy examples of scientific research conducted with synchrotron radiation are described. These are drawn principally from the X-ray region, and comprise X-ray fluorescence, small-angle scattering, powder profile refinement, extended X-ray absorption fine structure, topography, time-resolved spectroscopy, and VUV and photoelectron spectroscopy of solids. In conclusion, a few topics are mentioned relating to the future expansion and application of synchrotron radiation research facilities.     

同步辐射Laminar光栅的研制

采用全息离子束刻蚀和反应离子刻蚀相结合的新工艺 ,在熔石英基片上成功地刻蚀出 2 0 0l/mm、线空比 4:6、槽深 70nm、刻划面积 60× 2 0mm2 的浅槽矩形Laminar光栅。对改进光栅线条粗糙度和线空比的方法进行了系统的研究。这一新工艺相对简单 ,降低了对干涉系统光学元件和全息曝光显影的严格要求     

Topography with synchrotron radiation

The capability of synchrotron radiation topography compared to related crystal defect imaging techniques is discussed. Recent experimental highlights in white beam, double crystal, and stroboscopic topography are reviewed. An outlook upon future experimental trends in synchrotron radiation topography is given.     

Properties of synchrotron radiation

Muon capture on hydrogen gives a unique possibility for a measurement of the pseudo-scalar form factor g _p (q _c ² = -0.88 m _μ ² ) of the nucleonic weak current, thus providing a sensitive test of the QCD chiral symmetry perturbation theory which predicts the value of this form factor with a precision of Δg _p /g _p ≃ 2%. For adequate comparison with theory, the muon capture rate Λ_c should be measured with a precision of ΔΛ_c/Λ_c ≤ 1%, that is an order of magnitude better than the precision of the present world data. We report on the project of an experiment designed to provide the required precision. Also, we present the final result of our previous experiment on a high precision measurement of the μ³He capture rate and compare this result with the PCAC prediction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Coherence of synchrotron radiation

Gal'tsov et al. [Vestn. Mosk. Gos. Univ., Fiz., Astron.,14, No. 5, 614 (1973)] studied the radiation spectrum of N equally spaced charges moving along a circle. In particular, it was shown that as N the intensity of the radiation from the system of charges vanishes. The present study will consider the radiation spectrum of N charges moving along an arbitrary closed curve, randomly distributed in the vicinity of equally spaced points. The coherency factor will be found for the assumption that: a) the distributions of individual charges are not intercorrelated; b) the charge distribution is such that in the vicinity of a given point only one charge is found. It will be shown that as N the radiation intensity tends to a finite limit.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 8–11, March, 1988.     

同步辐射压弯镜重力补偿方法

介绍了同步辐射压弯镜重力引起的面型斜率误差及评价标准。根据梁的弯曲理论,提出了力矩加多点力补偿重力的方法,以上海光源XAFS光束线(BL14W)中的压弯镜为例,计算出力矩加两点力、力矩加三点和力矩加四点力补偿的最小斜率均方根误差分别为0.092,0.041,0.022 μrad。补偿结果的对比表明,当镜子两端有力矩补偿时,各补偿力相应减小,力矩加两点力、力矩加三点力和力矩加四点力补偿的面型斜率误差分别为没有力矩补偿时的52%,61%,68%。力矩加多点力补偿重力的方法明显优于多点力补偿重力的方法。     

Microvascular imaging using synchrotron radiation

In vascular diseases, the involvement of small vessels can be very crucial physiologically. Morphological changes of vasculature and alterations may be promising characteristic criteria for investigating disease progression and for evaluating therapeutic effects. Visualization of microvasculatures is an important step in understanding the mechanism of early vessel disorders and developing effective therapeutic strategies. However, the microvessels involved are beyond the detection limit of conventional angiography, i.e. 200 µm. Thus, faster and higher‐resolution imaging technologies are desired to capture the early anatomical structure changes of vasculatures in study of the disease. A new angiography system, synchrotron radiation microangiography, has been developed in this study. It allows for enhanced sensitivity to contrast agents and superior image quality in spatial resolution. Iodine and barium sulfate were used as blood vessel contrast agents. Physiological features of whole‐body mouse microvasculature were investigated using synchrotron radiation for the first time. The intracranial vascular network and other blood vessels were observed clearly, and the related anatomy and vessel diameters were studied. Dynamic angiography in mouse brain was performed with a high spatial image resolution of around 20–30 µm. Future research will focus on the development of novel specific targeting contrast agents for blood vessel imaging in vivo with a long half‐life and fewer side effects.     

X-ray synchrotron radiation in medium

Energy and angular distributions of X-ray synchrotron radiation produced by an ultra relativistic electron moving in a medium are discussed. Calculations show that the medium suppresses strongly the yield of the radiation for the electron Lorentz factor smaller than some cut-off value depending on the medium electron density and magnetic field applied.     

Nuclear physics with synchrotron radiation

The characteristics of synchrotron radiation originating from a very high energy electron-positron storage ring are presented. Emphasis is put on the high energy part of the spectrum which is relevant to nuclear physics research. The physics potential of such intense photon beams is reviewed with discussions of photonuclear reactions and of neutron-induced reactions with photoproduced neutrons.     

Infrared spectroscopy with synchrotron radiation

Up to now, storage rings have been used as sources of radiation on the X-ray and the u.v. part of the spectrum. It is shown that, with a specially designed part, a storage ring like ACO at Orsay is a very powerful far-infrared source, whose advantages over classical wide band sources are reviewed.     

Quantum effects in synchrotron radiation

The error in the recently published paper of Latal and Erber [4] on the quantum theory of synchrotron radiation is shown.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 44–48, December, 1979.In conclusion, the authors are grateful to Prof. J. Schwinger and Dr. Wu-Yang Tsai for providing the preprint [8].     

Electromagnetic and gravitational synchrotron radiation

A brief survey of the theory of synchrotron radiation (SR) is presented, with particular attention to quantum effects in the SR spectrum. The inaccuracy of the recent paper by Latal and Erber, considering quantum corrections to the classical SR spectrum, is pointed out. Some mechanisms of generation of gravitational radiation arealso discussed: gravitational SR, creation of gravitons in annihilation processes, and plasma generation of gravitational waves.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 46–53, February, 1980.     

Heterodyne detection of synchrotron radiation

A time integral method for the study of resonant nuclear scattering of synchrotron radiation in the forward direction is presented. The method relies on the interference of radiation scattered by nuclei in two samples, one moving with respect to the other. The method, termed heterodyne detection of synchrotron radiation, gives the same information on hyperfine parameters as the well known differential method. The general formalism is developed for the case where the reference is a single line sample and the investigated sample has magnetic or quadrupole splitting. The first experiments are discussed. A comparison of time differential synchrotron radiation spectroscopy, heterodyne detection and Mössbauer spectroscopy is given.     

北京同步辐射装置上的位相衬度成像

在北京同步辐射装置上首次用位相衬度成像方法对生物样品和复合材料进行研究,得到了非常清晰而精细的材料内部细观结构.其图像的清晰度和分辨率明显地优于吸收衬度成像 关键词： 位相衬度成像 相干光源 同步辐射硬X射线