The impact of synchrotron radiation on biology

The speakers at the main session of the 2005 National Synchrotron Light Source (NSLS) Annual Users' Meeting, held on Tuesday, May 24, at Brookhaven National Laboratory (BNL), spoke on many different topics. But they all conveyed excitement for the science performed at the NSLS, and expressed enthusiasm for its proposed successor, the world-leading NSLS-II.

The incoming NSLS Users' Executive Committee Chair, Peter Stephens, welcomed the audience to the main meeting, setting a positive and enthusiastic tone for the day's events. He then opened the stage to BNL Director Praveen Chaudhari.

Chaudhari commended many attendees for their work to advance NSLS-II.     

The impact of infrared synchrotron radiation in biology: Past,present and future

The Synchrotron Radiation Center (SRC) at the University of Wisconsin-Madison was shut down permanently in March 2014. It began operation in 1968 as the world's first dedicated synchrotron radiation user facility. This revolutionary idea of using synchrotron radiation for broad support of science and technology proved a resounding success, and it subsequently led to worldwide development of ever more powerful light sources for R&;D in many major scientific and technical areas. With upgrades and groundbreaking initiatives, SRC remained a cutting-edge and cost-effective facility to the end. SRC filled an important niche for tough experiments that were not possible at the newer facilities, given their beam time constraints. The world of IR, VUV, and soft X-ray research has been diminished by its loss, but its closing was necessitated by higher priorities at the US NSF.     

The polarisation of gravitational synchrotron radiation

In the linear approximation we show that the gravitational radiation induced by ultrarelativistic charges, moving in a magnetic field or in the field of a circularly polarised electromagnetic wave does not have the primary linear polarisation contrary to the case of the electromagnetic synchroton radiation.     

The spectral maximum of synchrotron radiation

A three-level system is considered as a simplest example where a possibility of solving the spectral problem is observed. We thoroughly analyze the relation between the amount of radiation emitted by the particle during the transitions to the first excited state and to the ground state. Generalizing basic expressions we can follow the evolution of spectral maximum. It turns out there is a condition for radiation maximum to stay at highest harmonic.     

激光同步辐射光源的辐射条件

激光同步辐射光源是一种新型的X射线光源，它利用高强度激光与相对论电子束发生康普顿散射，从而在电子的运动方向上辐射出X射线．本文在考虑电子的反冲基础上，利用康普顿散射研究了激光同步辐射光源（LSS）辐射光子的精确波长和能量；同时发现，对于背散射情况，只有当种子激光的波长λ1大于电子的物质波波长λm时才能发生LSS辐射；最后给出LSS辐射的极值波长λ2max=h/（m0γv）和极值能量εc2max=βε3.     

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.     

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.     

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.     

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].     

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.     

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.