Commercial flatbed scanners have the potential to deliver a quick and efficient means of capturing the scientific content of spectra recorded on photographic plates. We discuss the digitization of selected spectra in the Dominion Astrophysical Observatory (DAO) photographic plate collection with commercial scanners. In this pilot study, emphasis is placed on assessing if the information on the plates can be recovered using Epson V800 and 12000XL scanners; the more complicated issues associated with the shortcomings of photographic materials, such as correcting for nonlinearity, are deferred to a future study. Spectra of Vega that were recorded over ~4 decades with the DAO 1.8 meter telescope are examined. These spectra sample a range of photographic emulsions, plate preparation techniques, calibration information, observing techniques, and spectrograph configuration. A scanning density of 2400 elements per inch recovers information in the spectra. Differences in the modulation transfer function (MTF) of the two scanners are found, with the Epson 12000XL having a superior MTF. Comparisons with a CCD spectrum of Vega confirm that moderately weak features are faithfully recovered in p
This work investigates the dose-response curves of GAFCHROMIC EBT, EBT2, and EBT3 radiochromic films using synchrotron-produced monochromatic x-ray beams. EBT2 film is being utilized for dose verification in photoactivated Auger electron therapy at the Louisiana State University CAMD synchrotron facility. Monochromatic beams of 25, 30, and 35 keV were generated on the tomography beamline at CAMD. Ion chamber depth-dose measurements were used to determine the dose delivered to films irradiated at depths from 0.7 to 8.5 cm in a 10x10x10-cm3 PMMA phantom. AAPM TG-61 protocol was applied to convert measured ionization into dose. Films were digitized using an Epson 1680 Professional flatbed scanner and analyzed using the net optical density (NOD) derived from the red channel. A dose-response curve was obtained at 35 keV for EBT film, and at 25, 30, and 35 keV for EBT2 and EBT3 films. Calibrations of films for 4 MV x-rays were obtained for comparison using a radiotherapy accelerator at Mary Bird Perkins Cancer Center. The sensitivity (NOD per unit dose) of EBT film at 35 keV relative to that for 4-MV x-rays was 0.73 and 0.76 for doses 50 and 100 cGy, respectively. The sensitivity of EBT2
Purpose: A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: a) is it possible to employ this dosimetric system in reflection mode; b) if so, can the methods used in transmission mode also be used in reflection mode; c) is it possible to obtain accurate absolute dose measurements with Gafchromic EBT2 films; d) which calibration method should be followed; e) which calibration models should be used; f) does three-color channel dosimetry offer a significant improvement over single channel dosimetry. The purpose of this paper is to help clarify these questions. Conclusions: Reflection mode with Gafchromic EBT2 radiochromic film was found to be a viable alternative to transmission mode. The same methods that are used in transmission mode can be followed in reflection mode. A novel plan-based method was developed for calibration and multichannel dosimetry. This novel method offers increased robustness against film response inhomogeneities and reduces considerably the time required fo
Scientists in Germany have pulled off a staggering computing feat by fully simulating a 50-qubit quantum computer for the first time ever using Europe’s new exascale supercomputer, JUPITER。 The breakthrough shatters the previous 48-qubit record and highlights just how powerful next-generation supercomputers have become
Astronomers have spotted something surprising in the far outer Solar System—a faint, short-lived atmosphere clinging to a tiny icy world that shouldn’t be able to hold one at all。 The object, called 2002 XV93, is far smaller than Pluto, yet observations during a rare stellar alignment revealed its presence through a subtle dimming of starlight。 Eve
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It's not entirely clear how the exploit works。 Microsoft says it's investigating
Scientists have taken a major step toward ultra-secure quantum communication by demonstrating a remarkably stable quantum encryption system that worked across more than 120 kilometers of optical fiber。 Using tiny semiconductor quantum dots that emit single particles of light on demand, the team achieved one of the highest secure key rates yet for t
Earth is quietly collecting radioactive debris from an ancient stellar explosion as our Solar System drifts through a giant cloud of gas and dust between the stars。 Scientists analyzing Antarctic ice up to 80,000 years old discovered traces of iron-60 — a rare isotope forged in supernova explosions — and found evidence that this “cosmic ash” has be
A team at the University of Hong Kong has developed a new “super steel” that can survive the harsh conditions needed to make green hydrogen from seawater。 The material uses an unexpected double-protection mechanism that resists corrosion far better than conventional stainless steel。 Even more impressive, it could replace costly titanium parts used
Scientists studying mysterious ultra-powerful cosmic rays have uncovered a surprising hidden pattern that could finally help explain where these particles come from。 Using the DAMPE space telescope, researchers found that cosmic ray particles—from tiny protons to heavy iron nuclei—all begin fading away more sharply at the exact same point, hinting
Hubble has revealed a giant planet-forming disk unlike anything astronomers have seen before。 Nicknamed “Dracula’s Chivito,” the enormous structure appears turbulent and oddly lopsided, with towering filaments visible on only one side。 The disk contains enough material to potentially create multiple giant planets, making it a fascinating new labora
For nearly 100 years, reinforced rubber has powered everything from car tires to airplanes, yet scientists never fully understood why adding tiny particles of carbon black made rubber so incredibly strong。 Now, researchers at the University of South Florida have finally cracked the mystery using massive computer simulations that took the equivalent
Astronomers using the James Webb Space Telescope have spotted something that shouldn’t exist—at least not so early in the universe。 A massive galaxy, formed less than 2 billion years after the Big Bang, appears to have no rotation at all, a trait usually seen only in much older, evolved galaxies。 This challenges current theories that young galaxies
Physicists may have just cracked open a hidden side of the quantum world。 For decades, every known particle was thought to belong to one of two categories — bosons or fermions — but researchers have now shown that bizarre “in-between” particles called anyons could also exist in a one-dimensional system。 Even more exciting, these strange particles m