thanks! target info always welcome...
somebody should just redo the numbers below. However it will not change
dramatically since we are after a relative change in the conductance (not
the abs value).
--t
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124 research
scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Thu, 27 May 2004, Ernie Ihloff wrote:
> Tancedri,
>
> You are not using the correct inlet tube dimensions.
>
> It is 11.9 mm by 101 mm plus the 22 mm attached to the target
>
> so final dimensions now 11.9 mm ID by 123 mm long.
>
> Ernie
>
> Tancredi Botto wrote:
> > Hello,
> > for the sake of today's 40/60 cm discussion
> >
> > ### rate comparison hydrogen data for unpol system####
> >
> > _ Assumes: only M=2 flow, events in +- 15 cm (Helastic_tight, no cerenkov)
> > Elastic yield = N_events/ charge/ Buffer inlet P
> >
> > _ the elastic yield for runs with V14 CLOSED (runs 7424 vs 6864) increased
> > a factor of 12.9/7.8 = 1.65. The expected value is 1.8 (assuming perfect
> > cilindrical geometry, neglecting valved off injection tube)
> >
> > _ the same elastic yield for runs with V14 OPEN (runs 7556 vs 5471)
> > increased by a factor of 11.3/9.7 = 1.2. This should be compared to
> > 1.4 (15 x 130 mm inlet tube, at 300 K)
> > 1.5 (15 x 130 mm inlet tube, at the same temperature as the cell
> > wings)
> >
> > _ So the rate is ~ 10 % lower than expected when v14 is CLOSED, and ~
> > 15-25 % lower when v14 is OPEN. Note I integrate over +- 15 cm
> >
> > _ all in all, the remaining discrepancy is 15-25 % A scenario with an
> > inlet tube at 300 K is favoured, but the overall difference is not big,
> > given that if the inlet tube is at room temp, it is at room T for both cells.
> > I always assume a 15 mm x 130 mm inlet tube
> >
> > _ In summary V14 open data : unpol (one run) measure 1.2, ABS measure 1.3
> > density increase with a 60 cm cell. For the higher ABS increase one may
> > invoke a higher molecular fraction at 60 cm (*relative* to 40)
> >
> > _ Notes: always > 1000 cnts in the sample and the error assuming a linear
> > Pbuffer dependence is 5 % at worst (fit gives (P_inlet)^1.075 dependence)
> >
> >
> > ### eep comparison polarized deuterium data####
> >
> > _ In the first attachment I show the missing mass spectrum for d(ee'p)n
> > events. Black is 40 cm, red is 60 cm ABS data. Also shown in the second
> > plot is the contamination as measured in in empty target runs. All data
> > is normalized to charge.
> >
> >
> > Asymmetries are essentially calculated from data in this Mm distribution,
> > selected around the M_neutron peak. Apart from a yield increase in the
> > ABS, the data has not significantly changed from 40 to 60 cm cell. Please
> > note that the ABS realignement brought a 10 % increase of the yield.
> >
> > Empty-cell background appears to have not increased for 60 cm cell, and
> > ABS data do not look any different for 40 and 60 cm cells. I doubt
> > "background" is an explanation of the lower polarization data.
> >
> >
> > ________________________________________________________________________________
> > Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
> > research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
> >
> > ------------------------------------------------------------------------
> >
> >
> > ------------------------------------------------------------------------
> >
>
>
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