Abstract: We investigate the radiation spectrum incident on the back end of a scale-1 halfraum, and compare it to that measured by DANTE, at q = 37.4 deg. We use a simplified beam pointing and halfraum geometry and test three representative XCE-albedo values and four pointings.
The radiation temperature seen by a witness plate on the end of a halfraum is up to 15 eV less than that seen by DANTE when the beams are pointed less than 500 mm into the halfraum. The temperatures are closer for deeper pointings, with the witness plate TR exceeding DANTE’s in cases of low albedo.  These results are modified somewhat by the inclusion of a LEH lip on the halfraum, and by changes to the focus offset and more complex beam pointing schemes.
The spectrum seen by a witness plate on the end of a halfraum differs significantly from the spectrum seen by DANTE, even when their radiation temperatures are the same, with the witness plate spectrum being harder.