Question: What is the term for a period of low X-ray emissions?
About the article "Black hole", section "X-ray binaries".

Candidate passages:
Beta Doradus (Beta Dor, β Doradus, β Dor) is the second brightest star in the southern constellation of Dorado.
It has an apparent visual magnitude of 3.63, making it visible to the naked eye from the southern hemisphere.
Based upon parallax measurements with the Hubble Space Telescope, it is located at a distance of from Earth.
Beta Doradus is a Cepheid variable that regularly changes magnitude from a low of 4.05 to a high of 3.45 over a period of 9.842 days.
The light curve of this magnitude change follows a regular saw-tooth pattern.
During each radial pulsation cycle, the radius of the star varies by ±3.9 times the Sun's radius around a mean of 67.8.
Its spectral type and luminosity class are likewise variable, from F-type to G-type and from a supergiant to a bright giant.
Far ultraviolet emissions have been detected from this star with the Far Ultraviolet Spectroscopic Explorer, while X-ray emissions were detected with the XMM-Newton space telescope.
The X-ray luminosity is about 1 × 1029 ergs/sec and the emission varies with the pulsation period, suggesting a connection with the pulsation process.
The peak X-ray emissions are in the 0.6–0.8 keV energy range, which occurs for plasmas with temperatures of 7–10 million K. 
The production of X-rays by a bolt of lightning was theoretically predicted as early as 1925 but no evidence was found until 2001/2002, when researchers at the New Mexico Institute of Mining and Technology detected X-ray emissions from an induced lightning strike along a grounded wire trailed behind a rocket shot into a storm cloud.
In the same year University of Florida and Florida Tech researchers used an array of electric field and X-ray detectors at a lightning research facility in North Florida to confirm that natural lightning makes X-rays in large quantities during the propagation of stepped leaders.
The cause of the X-ray emissions is still a matter for research, as the temperature of lightning is too low to account for the X-rays observed.
A number of observations by space-based telescopes have revealed even higher energy gamma ray emissions, the so-called terrestrial gamma-ray flashes (TGFs).
These observations pose a challenge to current theories of lightning, especially with the recent discovery of the clear signatures of antimatter produced in lightning. 
X-ray astronomy satellites study X-ray emissions from celestial objects.
Satellites, which can detect and transmit data about the X-ray emissions are deployed as part of branch of space science known as X-ray astronomy.
Satellites are needed because X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and satellites.
A detector is placed on a satellite which is then put into orbit well above the Earth's atmosphere.
Unlike balloons, instruments on satellites are able to observe the full range of the X-ray spectrum.
Unlike sounding rockets, they can collect data for as long as the instruments continue to operate.
In one instance, the Vela 5B satellite, the X-ray detector remained functional for over ten years. 
Monochromatic X-rays to induce Inner Shell Ionization.X-ray Tube with Transmission Target for Line-Emissions.
Monochromatic X-rays can be channeled from synchrotron radiation, obtained from Coolidge X-ray tubes with extensive filtering, or from the preferred transmission X-ray tubes.
To induce an inner shell ionization with resonant scattering from a moderately heavy atom with dozens of electrons, the X-ray photon energy must be 30 kV or higher in order to be effective to penetrate tissues for therapeutic applications.
Synchrotron radiation is extremely bright and monochromatic without thermal scattering loss, but its brightness falls off at the 4th power of the photon energy, and at 15-20 kV or higher, a low cost X-ray tube with a Moly target for example, could deliver as much X-ray fluence as that of a typical moderately-sized synchrotron instrument.
In fact, the Coolidge X-ray tube becomes bright by (kVp)1.7 while the synchrotron brightness goes like (kV)-4, implying that it is generally not useful for desired Auger therapy.
Coolidge X-ray tubes become brighter at higher energies, but by using external filters to haverst the useful photons without having the tissue to be exposed to unnecessary skin dose, the X-ray tube fluence must typically reduce by two orders or more in brightness, which is not an ideal case for therapy applications.
This leaves the unique X-ray tube with end-window transmission targets.
In a transmission X-ray target, the X-rays are harvested along the direction of the e-beam path, in contrast to the conventional Coolidge tube where the X-rays from a solid target are collected mostly at 90° from the e-beam path.
The said X-ray beam has a sharp cut-off blocked by the target material at angles much beyond 90°, and becomes much softer at angles below 90°.
As a result, the useful X-ray beam from a typical Coolidge tube is only 12-14o, although such a narrow cone could be extended along the surface of the solid target to result with a fan-beam that is commonly employed for body-slicing in computed tomographic (CT) imaging.
To harvest the X-ray fluence at 90° from the e-beam path is indeed an optimal position in brightness without relativistic transform.
Being six years older than Einstein, Coolidge at the turn of the 20th century did not engage the proper electron dynamics with his design, the hundred years old patented X-ray tube including the rotational anode design for heat spread for higher thermal load.
With relativistic transform, the bremsstrahlung trajectories become forward leaning, moving along the e-beam direction, and if the X-ray fluence is collected from the transmission target in the forward direction and integrated over the azimuth angles, the X-ray fluence could typically be several hundredfold enhanced as compared to the Coolidge tube.
More importantly, the e-beam range in an X-ray target material is only a few micrometres, so that for a 30 μm thick transmission X-ray target, most of the target thickness would function as a filter that not only absorbs the very low energy photons, but also transfers high energy photons into the fluorescent K or L-lines characteristic to the target element.
In addition, the monochromatic line-emissions are emitted from the same refined X-rayfocal point.
Figure 4.1 demonstrates the K-line emissions of Moly and Silver targets, showing that the transmission target would deliver mostly bright, monochromatic X-rays from the small X-ray focal point defined by the e-beam focus. 
Under the NZ ETS, all NZ Units will be distributed into the market by free allocation (gifting).
There is no intention in the short term to auction any NZ Units.
'Emissions-intensive' and 'trade-exposed' (EITE) activities are designated a benchmark level of emissions per unit of production.
For example, x amount of carbon dioxide equivalent emissions per tonne of steel.
Firms then receive an allocations based on their expected production of the emissions intensive good.
This method of allocation is often referred to as 'intensity based allocations'.
Intensity based allocations are allocations that are based on the volume of production of a firm.
Allocations are given at the beginning of the period and then balanced at the conclusion to reflect actual output.
The benchmark (or allocative baseline) for free allocation for firms considered emissions-intensive and trade-exposed includes compensation for electricity price increases.