Measurements of the dummy and flyswatter thicknessess:

Feb 2005. Used a micrometer. Measured flyswatter thickness to be 0.030" with about 1/4 mil variations over the surface in the vicinity of the (visible) spot where we had beam.

Measured several locations on the dummy target frame where we had the beam. Got 0.121" with about a 1/2 mil variation.

Here's something about the 2 upstream windows (the vacuum & the entrance window):

For the front (vacuum) entrance window we measured 2 of the spares:
6.7 mils avg at the center of one, and about 1 mil thicker 2-3 mm away from the center.
7.0 mils avg at the center of the other one, and about 0.5 mil thicker 2-3 mm away from the center.

For the nose, the window at the He/H2 boundary, which is supposed to be real thin since there is not supposed to ever be any differential pressure across it, and it's only 11mm in diameter, we measured 3 of the spares:
9.0 mils avg at the center of one, and pretty uniform (within a few tenths of a mil) out to a few mm from the center.
9.6 mils avg on another, again pretty uniform away from center like the one before.
8.7 mils on the third one, also uniform. This third one we also used a regular micrometer and got 9.2 mils. Note that all the other measurements were done with the Hall effect thickness gauge.

The 10 mil calibration standard was measured to be 10.2, that's an indication of the measurement uncertainty (~0.2 mils).

They all have a tiny nib at the exact center from machining that's a little bit thicker, little bit means something like 1/2 mil but it's such a tiny feature we can't really measure it reliably.



Prior to the fall of 2003, we had a thick exit cell. It was replaced with a new cell thinned to 3 mils over an 8 mm diameter nipple. Prior to this, the exit window was 11.1 mils thick. Here are the relevant emails with the numbers:

Dave Meekens and I measured the thickness of the
exit window for the current G0 cell using a Hall
effect thickness gauge:

at center 0.0107"
up 1mm 0.0112"
up 3mm 0.0111"
BR 1mm 0.0118"
BR 2mm 0.0109"
BL 1mm 0.0111"
BL 2mm 0.0110"
down 1mm 0.0109"
down 2mm 0.0112"

Reckeck calibration: zero fixture: 0.0000"
0.0100 standard 0.0105"

Mike Seely



Here are some more dimensions
(these pertain to the cell/target in use starting fall 2003). Here's a picture of the cell dimensions.


Oh yeah, by the way, here is a table of densities for liquid parahydrogen that might be useful.

And the following table lists densities for hydrogen gas in the temperature and pressure range we used for our background measurements.

Pressure Pressure Temp Density
kPa psia K g/cm^3








222.6 32.29 25 0.002475
222.6 32.29 25.5 0.002407
222.6 32.29 26 0.002343
222.6 32.29 26.5 0.002283
222.6 32.29 27 0.002227
222.6 32.29 27.5 0.002174
222.6 32.29 28 0.002124
222.6 32.29 28.5 0.002077
222.6 32.29 29 0.002032
222.6 32.29 29.5 0.001989
222.6 32.29 30 0.001948
222.6 32.29 30.5 0.001909
222.6 32.29 31 0.001872
222.6 32.29 31.5 0.001836
222.6 32.29 32 0.001802
222.6 32.29 32.5 0.001770
222.6 32.29 33 0.001738
222.6 32.29 33.5 0.001708
222.6 32.29 34 0.001679
222.6 32.29 34.5 0.001651
222.6 32.29 35 0.001624
222.6 32.29 35.5 0.001598
222.6 32.29 36 0.001573
222.6 32.29 36.5 0.001548
213.68 31.00 25 0.002360
213.68 31.00 25.5 0.002296
213.68 31.00 26 0.002236
213.68 31.00 26.5 0.002180
213.68 31.00 27 0.002127
213.68 31.00 27.5 0.002077
213.68 31.00 28 0.002030
213.68 31.00 28.5 0.001985
213.68 31.00 29 0.001943
213.68 31.00 29.5 0.001902
213.68 31.00 30 0.001864
213.68 31.00 30.5 0.001827
213.68 31.00 31 0.001791
213.68 31.00 31.5 0.001758
213.68 31.00 32 0.001725
213.68 31.00 32.5 0.001694
213.68 31.00 33 0.001664
213.68 31.00 33.5 0.001635
213.68 31.00 34 0.001608
213.68 31.00 34.5 0.001581
213.68 31.00 35 0.001555
213.68 31.00 35.5 0.001531
213.68 31.00 36 0.001507
213.68 31.00 36.5 0.001483
234.36 34.00 25 0.002629
234.36 34.00 25.5 0.002555
234.36 34.00 26 0.002486
234.36 34.00 26.5 0.002421
234.36 34.00 27 0.002360
234.36 34.00 27.5 0.002303
234.36 34.00 28 0.002249
234.36 34.00 28.5 0.002199
234.36 34.00 29 0.002150
234.36 34.00 29.5 0.002104
234.36 34.00 30 0.002061
234.36 34.00 30.5 0.002019
234.36 34.00 31 0.001979
234.36 34.00 31.5 0.001941
234.36 34.00 32 0.001905
234.36 34.00 32.5 0.001870
234.36 34.00 33 0.001836
234.36 34.00 33.5 0.001804
234.36 34.00 34 0.001773
234.36 34.00 34.5 0.001743
234.36 34.00 35 0.001715
234.36 34.00 35.5 0.001687
234.36 34.00 36 0.001660
234.36 34.00 36.5 0.001634