[Eg2] Target densities

[Dupré Raphaël]

Hi everybody,

After this afternoon meeting I have some concern about the values for the
target thickness especially Carbon.

In the NIM paper there is a table indicating areal densities as: C = .38 ;
Fe = 0.31 ; Pb = 0.16 g/cm2
Simple calculation with Hyupwoo numbers gives 2H = .325 g/cm2

Then ratios of electrons from the targets in data should give something
around: C = 1.17 ; Fe = .95 ; Pb = .49
I found with my cuts: C = .91 ; Fe = .96 ; Pb = .46 It is a good agreement
except for Carbon!

If I use Hyupwoo numbers for the Carbon areal density, I find the same than
in the NIM paper, but I am concerned with the value of 2.267 g/cm3 because
graphite seem to have variable density depending on the web site you
consult, what I could grab was that raw mineral graphite is between 2.09 and
2.3 g/cm3 but that once treated it can get much lighter (I seen 1.57, 1.7
and 1.8 in various places). On the NIST web site they use density of 1.7
g/cm3 for graphite and that would lead to an areal density of .29 g/cm2
which give a ratio in data of .90 in agreement with what I observe in data.

-- 
Raphaël Dupré


Argonne National Laboratory

Université Claude Bernard Lyon 1
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/eg2/attachments/20110111/787929ed/attachment.html