Hi Chi,
Is this normalization also present in the d(e,e'p) analysis?
Thanks,
Richard
On Tue, 29 Jul 2003, zhangchi wrote:
>
> Hi all,
>
> I would like to bring to your attention to the yields from recent unpol
> runs.
>
> since 22nd, we v been running with unpol gas with Mass Flow Controller
> dialed at different values, and I analyzed the yield from these run.
>
> Again I present the yield by equivalent gas flow assuming 100% detection
> efficiency:
>
> gas flow dialed flow from edelastic yield runs
> -------------------------------------------------------------
> 4.48 atoms/sec (0.05sccm) 1.67+-0.17 atoms/sec 1262-1277(June)
> 9.96 atoms/sec (0.1sccm) 7.82+-0.21 atoms/sec 1642-1725(7/22-
> 7.97 atoms/sec (0.08sccm) 3.69+-0.36 atoms/sec 1726-1730
> 4.48 atoms/sec (0.05sccm) 2.83+-0.09 atoms/sec 1731-1799
>
> the errors on the yield are estimated from the number of counts in the
> fastest counting bin Q^2 = 0.125-0.185 GeV^2
>
> yield/(dialed gas flow) varries from 37%(0.05sccm runs: 1262-1277) to
> 79%(0.1sccm runs: 1642-1725) and the two series of 0.05sccm runs one month
> apart produce rather different yields.
>
> Detection efficiency could well be varying during these days, due to the
> raise and lower of left box 6, however, there is definitely no evidence
> that the efficiency changed by a factor of 2.
>
> Again, this indicates the limit of the current flow control system. these
> 1sccm controlers provides errors of 1% full scale, calibrated with N2 gas.
> for D2 gas which has smaller mass, the uncertainty is 0.025sccm. when
> working at 0.05sccm, the error could be as large as 50%.
>
> It may be possible to calibrate the linear relation between real gas
> output and dialed value, but seems the validity of such a calibration over
> a long period of time is still questionable.
>
> It demonstrates again the need for a reliable and accuate gas flow system.
> Otherwise, calibration and monitoring of detector efficiency and target
> density would always be entangled and hard to resolve independantly and
> definitively.
>
> Chi
>
>
>
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