The X-1 Z-pinch driver

X-1 is a program initiative to develop the next-generation laboratory X-ray source using fast Z-pinch drivers. X-1 will provide unique applications utility to high-energy density physics, inertial confinement fusion, and radiation effects simulation research. The advent in the 1980's of pulsed power accelerators capable of delivering tens of terawatts to imploding plasma loads led to a quantum improvement in Z-pinch performance by reducing the implosion time to less than 100 ns. Further progress in Z-pinch performance capabilities was achieved in 1996, using a cylindrical wire-array load, and led to the production of 85 TW, 350-500 kJ of X-rays using the Saturn accelerator at Sandia. The PBFA-II accelerator has been converted to drive Z-pinch loads (PBFA-Z), and will provide a factor of 2 increase in current, and 4 in energy, over that provided by Saturn. X-1 is the next step beyond PBFA-Z and, as presently envisioned, represents a factor of 8 increase in energy. It will require a ~360 TW, ~100 ns pulsed power generator to impart ~16 MJ kinetic energy to the reference imploding plasma load. A baseline concept for X-1 has been developed. It utilizes a highly modular, robust architecture with demonstrated performance reliability     

Sneutrinos from Cygnus X-3?

The possibility that the underground muons arriving from Cygnus X-3 are due to a flux of sneutrinos is analyzed. Crude approximations show that the muons can be due to a resonance production of light charged gauginos produced in sneutrino-electron collisions.     

X射线及其医学应用

x射线即伦琴射线,俗称x光,在本质上是一种频率比紫外线更高的电磁波.1 X射线的性质 (1)它是肉眼看不见的一种射线,但可使某些化合物产生荧光或使照相底片感光. (2)它在电场或磁场中不发生偏转,能发生反射、折射、干涉、衍射等. (3)它具有穿透物质的本领,但对不同物质它的穿透本领不同.     

The rms-flux relation of Cyg X-2 in the horizontal branch

We have investigated the relation between the root mean square (rms) variability and the X-ray flux (rms-flux relation) of the Z source Cyg X-2, and as well the energy dependence based on the Rossi X-ray Timing Explorer (RXTE) observations. We currently focus on the horizontal branch (HB), due to the negative correlation in flux of the soft and the hard X-rays. The rms-flux correlation has energy dependence as follows: positive at hard X-rays (above 10 keV) but negative at soft X-rays (below 10 keV). This provides a feature different from the previous one, and may be suggestive of different origins of X-rays below and above 10 keV. Nevertheless, the overall spectrum can be well fitted with a model consisting of a blackbody and Comptonization components, but the fitting results do not reveal any features around 10 keV that could account for such a change in the rms-flux relation.     

亚仟X光扫描相机性能研究

本文介绍了亚仟X光扫描相机的工作原理和实验方法,测定并研究了相机的静态狭缝展宽、触发延迟时间、触发晃动、动态空间分辨率、扫速与非线性、动态范围、时间分辨率。     

X-[1H, 19F] triple resonance with a X-[1H] CP MAS probe and characterisation of a 29Si-19F spin pair

An economic approach for implementing X-[1H,19F] double-decoupling MAS NMR experiments with a conventional X-[1H] dual-channel CP MAS probe is demonstrated. The parameters characterising the isolated 29Si-19F spin pair in an organosilicon compound R(3)SiF (R = 9-anthryl) are determined. In addition, we discuss the optimum choice of experimental parameters for determining all 29Si-19F spin-pair parameters from straightforward 29Si MAS NMR spectra with only 1H decoupling applied during acquisition.     

Two-photon and Three-photon Fluorescence of Triton X-100 in the Ultraviolet Region

Journal of Fluorescence - We report, to our best knowledge, the first observation of two-photon and three-photon fluorescence of Triton X-100 (TX-100) in water and cyclohexane. The observed...     

A Multifrequency (X-, Q-, and W-band) EPR and DFT Study of a Photopolymerizable Dental Resin

The free radicals generated during the polymerization process of Z100 (3 M ESPE) dental resin were examined by electron paramagnetic resonance (EPR) in X-, Q- and W-bands. Experimental generation and spectra simulations were associated with density functional theory (DFT) calculations to determine the molecular structure and explain the EPR spectrum formation. It was assumed that the EPR spectrum was formed by the sum of two different types of radicals: “propagating” and allylic. The spectra simulations and DFT calculations showed good agreement, indicating that the proposed model fully explained the nine lines of the EPR spectrum in X-band and showed that the spectrum formation is the sum of “9 + 5” lines, rather than the “5 + 4” lines predicted early. Simulations in Q- and W-bands showed very close correlation and were essential to support the proposed model.     

Radiation from Cygnus X-3 and the related muon puzzle—An explanation

Summary In recent times there have been widespread speculations and claims among the cosmic-ray as well as high-energy physicists about the detection of some ?signatures? for the formation of what one calls the quark-gluon plasma states in the ultrahigh-energy cosmic-ray collisions involving heavy nuclei. Furthermore, there are reportedly some hints to the detection of such states in laboratory experiments as well. We have collected here what are, in general, believed to be the diagnostics for such quark-gluon plasma states and have also provided alternative explanations for all the relevant observations at laboratory energies and cosmic-ray energies. Thus the obvious conclusion is: the evidences claimed so far are neither unique and decisive nor are very substantial, tenable and conclusive, as one can understand them almost completely from an altogether different theoretical framework.

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Riassunto In tempi recenti vi sono state diffuse ipotesi ed affermazioni tra i fisici che si occupano dei raggi cosmici e dell'alta energia sulla scoperta di alcune ?impronte? per la formazione di quelli che si chiamano stati di plasma tra quark e gluoni in collisioni di raggi cosmici ad energia ultra alta che coinvolgono nuclei pesanti. Inoltre vi sono alcuni indizi a quanto viene riferito per la rivelazioni di questi stati anche negli esperimenti di laboratorio. Qui abbiamo raccolto quella che è in generale ritenuta la diagnostica per questi stati di plasma fra quark e gluoni ed abbiamo inoltre fornito spiegazioni alternative per tutte le osservazioni relative ad energie di laboratorio ed energie di raggi cosmici. Cosí la conclusione ovvia è: le prove non si sono dimostrate né uniche e decisive, né importanti, sostenibili e conclusive, come le si può ritenere quasi completamente da un modello teorico completamente diverso.

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Резюме В последнее время в физике космических лучей и физике высоких энергий интенсивно обсуждается вопрос детектирования некоторых ?сигнатур? для образования так называемых состояний кварк-глюонной плазмы при соударениях космических частиц ультравысоких энергий, включая тяжелые ядра. Более того, были также публикации о предлагаемом детектировании таких состояний в лабораторных экспериментах. В этой работе анализируется диагностика таких состояний кварк-глюонной плазмы, а также предлагаются альтернативные объяснения всех имеющихся наблюдений при лабораторных и космических энергиях. На основе анализа делается очевидный вывод: данные наблюденй пока не являются достаточными, чтобы их можно было бы понять из полностью друтих теоретических подходов.

     

Optical identification of X- and gamma-ray sources: the use of existing data

Summary We briefly discuss the use of existing astronomical data, mainly deep optical observations performed in order to obtain galaxy and star counts, for the identification of gamma-ray burst sources in particular and of newly discovered X- and gamma-ray sources in general. Use of such data cannot only reduce the amount of required telescope time but also, in comparison with present-day observations, allow the search for variability and proper motion of candidate optical counterparts over a time span of several years. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Hard X-ray lags of Cygnus X-1 on short timescales

Calculating the time lags over different timescales using the cross-correlation technique may lead to a biased estimate of small timescales. Given a timescale for lightcurve binning, we propose to subtract the local average instead of the global average during the cross-correlation, in order to filter variations on timescales larger than the bin size. The new method allows us to make an unbiased estimate of the time lags using RXTE/PCA data on timescales as small as ∼5 ms, where the Fourier technique becomes invalid. We calculate the time lag spectra of Cygnus X-1 at different spectral states with the new method, and find that the source appears to have similar X-ray lags on small timescales independent of its spectral states.