Hi chi,
regarding your relative rate question: in reality the cell
conductance is Ctot = Cinlet + Cside(20) + Cside(20)
The injection tube is 130 mm x 15 mm (????) so that
Cinlet ~ 1.5 Cside(20) Ctot ~ 3.5 Cside(20)
In going from 40 -> 60 cm long cells you get that
Cside = Cside(30) = 2/3 Cside(20)
Cinlet did not change between 40 and 60 cm therefore
Ctot = 1.5 Cside(2) + 2 *2/3 Cside(20) ~ 2.83 Cside(20)
Therefore the gas density at the center of the cell, with Cinlet
open (or -say - V14 open) only increases by a factor of 1.2 all
others things being equal
An additional factor comes from integrating over the middle of
a triangle with a longer base. But being 1-|z|/L the triangular
distribution, the ratio of the integrals over +- x cm is
(x - (x^2)/2/L1 ) / (x - (x^2)/2/L2 ) and with x=20 cm, L1=30 and
L2=20 this should give an additional factor of 1.33. So for ABS
over +-20 cm you should expect a rate increase of 1.2*1.33 = 1.6,
significantly higher than the number of 1.27 that you report.
Note: after all cuts, are you really integrating over +- 20 cm ?
Of course a 20 % reduction of ABS flow could naively explain this
discrepancy. But it should be worse than that since now you can actually
make about 50 % more wall collision so expect more molecules, which
actually are slower and should increase your rate. I have not done the
comparison myself for eep with ABS, but I do get the right scaling when
comparing unpol hydrogen runs (V14 closed).
Note that - for the given inlet tube geometry - over the full lenght of
the 40 and 60 cm cells you should expect a maximum rate increase of
1.23*1.5 = 1.85.
-- tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Fri, 21 May 2004, Chi Zhang wrote:
>
> Hi, I m on A shift today and would like to skip the analysis meeting. :)
>
> Here are some updates:
>
> atatched is a plot of ed elastic rate (by my cuts). in the plot each data
> point represents one or two days statistics. there are three blocks
> seperated by big empty area. the first is the March 23-29 running: the ABS
> runs after holding field magnet coils are fixed. second block is May04-08:
> the first runs with 60cm cell. the 3rd block is runs between May
> 15th-20th: after work on SFT is completed. For 60cm runs, only center 40cm
> was used. Y scale is in counts/Coulumb. blue is for electron into left,
> red is for electrons into right. blue are consistantly higher than red.
>
> Every Columb into the target yields a quater deuteron in each sector.
>
> there is clearly an increase in rate switching to 60cm cell. the inrease
> is about 27% calculated by my code.
>
> in terms of polarization, ed elastic gives consistant answer with e'p.
> Tensor polarization in all the runs taken May15-20 is 27+-4%. When running
> average is taken it is:
>
> 15-16: 28+-9
> 15-17: 35+-6
> 15-18: 34+-5
> 15-19: 29+-5
> 15-20: 27+-4
>
> I seem to achieve most consistant fit for polarization in the two sectors
> when taking spin angle a bit less than 45 degrees for the latest runs,
> instead of 47.
>
> Chi
>
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