We present a Differential Emission Measure ( DEM ) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer ( EIS ) on Hinode .
We show that the expected quiet Sun DEM distribution can be recovered from judiciously selected lines , and that their average intensities can be reproduced to within 30 % .
We present a subset of these selected lines spanning the temperature range \log T = 5.6 to 6.4 K that can be used to derive the DEM distribution reliably , including a subset of Iron lines that can be used to derive the DEM distribution free of the possibility of uncertainties in the elemental abundances .
The subset can be used without the need for extensive measurements and the observed intensities can be reproduced to within the estimated uncertainty in the pre-launch calibration of EIS .
Furthermore , using this subset , we also demonstrate that the quiet coronal DEM distribution can be recovered on size scales down to the spatial resolution of the instrument ( 1 ^ { \prime \prime } pixels ) .
The subset will therefore be useful for studies of small-scale spatial inhomogeneities in the coronal temperature structure , for example , in addition to studies requiring multiple DEM derivations in space or time .
We apply the subset to 45 quiet Sun datasets taken in the period 2007 January to April , and show that although the absolute magnitude of the coronal DEM may scale with the amount of released energy , the shape of the distribution is very similar up to at least \log T \sim 6.2 K in all cases .
This result is consistent with the view that the shape of the quiet Sun DEM is mainly a function of the radiating and conducting properties of the plasma and is fairly insensitive to the location and rate of energy deposition .
This universal DEM may be sensitive to other factors such as loop geometry , flows , and the heating mechanism , but if so they can not vary significantly from quiet Sun region to region .