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A hydrogen atom with proton and electron spins aligned (top) undergoes a flip of the electron spin, resulting in emission of a photon with a 21 cm wavelength (bottom) The hydrogen line, 21 centimeter line, or H I line [a] is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms.
These are predominantly hosted in galaxies, so the neutral hydrogen signal is effectively a tracer of the galaxy distribution. As with galaxy redshift surveys, intensity mapping observations can be used to measure the geometry and expansion rate of the Universe (and therefore the properties of dark energy [ 1 ] ) by using the baryon acoustic ...
Consumer Reports (CR), formerly Consumers Union (CU), is an American nonprofit consumer organization dedicated to independent product testing, investigative journalism, consumer-oriented research, public education, and consumer advocacy.
It's been nearly three weeks since the iPhone 4 went on sale. But it wasn't until yesterday that Consumer Reports, the ultimate authority in which big-ticket items to buy and which to bypass ...
Consumer Reports is a United States-based non-profit organization which conducts product testing and product research to collect information to share with consumers so that they can make more informed purchase decisions in any marketplace.
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is an interferometric radio telescope at the Dominion Radio Astrophysical Observatory in British Columbia, Canada which consists of four antennas consisting of 100 x 20 metre cylindrical parabolic reflectors (roughly the size and shape of snowboarding half-pipes) with 1024 dual-polarization radio receivers suspended on a support above ...
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Nonetheless, Ewen and Purcell agreed that his thesis topic should be to construct a microwave spectrometer to find a lower limit on the detectability of the 21-cm hydrogen line. [6] With a $500 grant from the AAA&S, Ewen was able to purchase components to construct a pyramidal horn antenna and a 21-cm receiver.