new XRA attenuation target - Part 22

BrianClement / Demo3

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new XRA attenuation target - Part 22 #197

Open BrianClement opened 7 years ago

BrianClement commented 7 years ago

DB0079 [Created: 2016-12-11]

The current XRA attenuation target:

does not fit well into the daily cassette leading (probably) to misalignment w.r.t. the travel direction (~1.5mm over total length)
contains a defect on the 24-20 mm strip boundary.

Consensus is that the defect will be hard to repair. It also seems that the target is made from more than a single block of material opening up the possibility of sattenuation differences not solely arising from thickness variation.

The new target should be machined from a single block of material and have an overall size that permits alignment to be adjusted on fitting into the daily cassette.

The current target (with the current source settings) delivers transmissions from 50 to 90% which covers the range seen for 25 mm thick dry radiata samples (60-90% transmission). However, it might be worth altering the strip thicknesses to broaden the range of transmissions. Maybe 4, 16, 28, 40, 52, 64 mm (equivalent to transmissions of 88, 62, 44, 30, 21, 15% using current settings). Mind you having a 64 mm thick aprt to the daily calibration jig might be problematic. Opinions?

BrianClement commented 7 years ago

[Jonathan - 13/12/2016 1:40:50 p.m.]

BrianClement commented 7 years ago

[John Lee - 20/01/2017 1:45:14 PM]