[b1_ana] Fwd: comments/questions to PR12-13-011
Elena Long
ellie at jlab.org
Mon Jun 10 15:09:34 EDT 2013
test of Close-Kumano sum rule - it is very hard to do such test with
limited coverage in x, may be some
estimates of contribution measured/extrapolated can be done for specific
models. For the models mentioned
on page 17 - can one get some idea what would be the contribution in
measured range?
RESPONSE : Yes, this in an excellent suggestion. G. Miller and M.
Sargian have provided us their curves. We need to integrate to see the
contributions for x<0.15 and x>0.5. (Ellie, I think you have these
now. Can you look into this?)
------------------------------
Ellie:
The calculations below show the integral over certain x ranges for three
different types of PDFs used in the calculation of b1. They were
calculated using step sizes of x=0.001 with INT(b1,x) =
SUM(b1(x)*stepsize) where b1(x) is a calculate value of b1 at a
particular x value.
------------------------------------------------------------------------------------------
For Miller, the integrated sums over particular ranges are:
Range & PDF Type & Sum
0.0001 < x < 0.998 & CTEQ5 & -0.00931
0.0001 < x < 0.998 & MRST2001LO & -0.00931
0.0001 < x < 0.998 & MSTW2008LO & -0.00931
0.0001 < x < 0.15 & CTEQ5 & +0.00200
0.0001 < x < 0.15 & MRST2001LO & +0.00200
0.0001 < x < 0.15 & MSTW2008LO & +0.00200
0.0001 < x < 0.5 & CTEQ5 & -0.00267
0.0001 < x < 0.5 & MRST2001LO & -0.00267
0.0001 < x < 0.5 & MSTW2008LO & -0.00267
0.5 < x < 0.998 & CTEQ5 & -0.00664
0.5 < x < 0.998 & MRST2001LO & -0.00664
0.5 < x < 0.998 & MSTW2008LO & -0.00664
------------------------------------------------------------------------------------------
For Misak, the integrated sums over particular ranges are:
Range & PDF Type & Sum with vn &
Sum with lc
0 < x < 0.245 & N/A & Model does not apply
0.245 < x < 0.998 & CTEQ5 & -0.000181 & -0.000135
0.245 < x < 0.998 & MRST2001LO & -0.000146 & -0.000109
0.245 < x < 0.998 & MSTW2008LO & -0.000172 & -0.000129
0.245 < x < 0.5 & CTEQ5 & -0.000191 & -0.000141
0.245 < x < 0.5 & MRST2001LO & -0.000152 & -0.000112
0.245 < x < 0.5 & MSTW2008LO & -0.000184 & -0.000136
0.5 < x < 0.998 & CTEQ5 & +0.000010 & +0.000006
0.5 < x < 0.998 & MRST2001LO & +0.000006 & +0.000003
0.5 < x < 0.998 & MSTW2008LO & +0.000012 & +0.000007
------------------------------------------------------------------------------------------
For Kumano, the integrated sums over particular ranges are:
Range & PDF Type & Sum Without Sea&
Sum With Sea
0.0001 < x < 0.998 & CTEQ5 & +0.00183 & +0.00820
0.0001 < x < 0.998 & MRST2001LO & +0.000604 & +0.0104
0.0001 < x < 0.998 & MSTW2008LO & +0.000266 & +0.00767
0.0001 < x < 0.15 & CTEQ5 & +0.00296 & +0.00901
0.0001 < x < 0.15 & MRST2001LO & +0.00147 & +0.0109
0.0001 < x < 0.15 & MSTW2008LO & +0.00143 & +0.00849
0.0001 < x < 0.5 & CTEQ5 & +0.00226 &
+0.00848
0.0001 < x < 0.5 & MRST2001LO & +0.000917 & +0.0106
0.0001 < x < 0.5 & MSTW2008LO & +0.000712 & +0.00796
0.5 < x < 0.998 & CTEQ5 & -0.00043 &
-0.00028
0.5 < x < 0.998 & MRST2001LO & -0.000313 & -0.0002
0.5 < x < 0.998 & MSTW2008LO & -0.000446 & -0.00029
Take care,
Ellie
Elena Long, Ph.D.
Post Doctoral Research Associate
University of New Hampshire
elena.long at unh.edu
ellie at jlab.org
http://nuclear.unh.edu/~elong
(603) 862-1962
On 06/09/2013 11:07 PM, Karl Slifer wrote:
>
> Hi all,
>
> Below please find a draft response to the readers. I'd appreciate
> any/all feedback.
>
> Thanks to Oscar and Dustin for sending comments already. I hope I
> have incorporated them satisfactorily, but let me know if not.
>
> Dustin : any ETA for the updates to the technote? Ideally we can send
> them this short email and then provide your note for the full details.
> Most important would be to clarify the overall drift numbers, as I had
> the same confusion that Ellie raised.
>
> I'll have time to work on this tomorrow morning and early afternoon,
> but have to leave for DC mid afternoon. I'd love to get a response to
> Ewa before then if possible.
>
> thanks much,
>
> -Karl
>
>
> -----------------------------
>
> The measurement is very sensitive to the systematic effects and good
> control of them is the
> key point. Therefor I would like to know if there are any estimates of
> expected size of effects from:
>
> RESPONSE: We agree with the TAC assessment that systematic errors from
> drifts must be mitigated, but
> that they are manageable with a combination of
> hardware upgrades and a dedicated collaboration
> effort. We note that the recent g2p experiment
> involved a similar situation where a significant
> commitment was made to install and run this
> polarized target, but separate groups were tasked
> with substantial tasks of beamline, DAQ and
> detector upgrades. We are grateful to the TAC for
> pointing out several effects which were not
> explicitly discussed in our submitted proposal. We
> have written a short note discussing each of
> these and conclude that the overall systematic
> uncertainty is still of the same order as
> estimated in the proposal.
>
> 1. beam - one aspect is the stability in terms of position and divergency
> this can change acceptance and produce false asymmetries
>
> RESPONSE: (The TAC report pointed out that the false asymmetries from
> beam position drifts are easily
> removed by "regression". Can someone fill in the
> details? I assume that this just means
> that the parity feedback on position is very good,
> but we need some numbers/examples to
> back this up. This is dealt with in section 1.1.4
> of the note, but there are few details.)
>
> 2 beam polarization - how the unpolarized beam will be obtained what
> kind of effects are
> expected from beam polarization (ie. to which level exact
> averaging of opposite beam polarity
> is needed and how the phase space of the beam is polarization
> dependent)
>
> RESPONSE: JLab E06-010 (Transversity) spin-averaged a highly polarized
> (~80%) beam in order to
> obtain an "unpolarized" beam. The parity
> feedback allowed for knowledge of the residual
> beam polarization at the 2.2*10^{-5} level,
> according to the lumi monitors. Please see attached
> plot, which shows the beam asymmetry from that
> experiment.
>
>
> 3. temperature effects on the efficiency (and stability of the
> detectors allignment) - proposed scheme
> of polarization reversals will give data with target polarization
> during the day and unpolarized
> at night or vice versa. This can introduce false asymmetry
> related to any kind of temperature
> dependence in efficiency or allignment. Was it estimated ? Are
> there any studies of this kind of effects
> in previous experiments?
>
> RESPONSE: (This could be addressed by the transversity slides, but I'm
> not sure if the pion yield plot
> addresses this. The main sensitivity to
> temperature will be the BCMs and Dave has plans
> to isolate them, but I don't have any details of
> that yet.)
>
>
>
> 4. for the drift of efficiency and its time dependence (page 25)
> linear evolution in time is assumed.
> for which effects it is justified? It is clear that for example
> changes in packing factor of dilution factor
> can have "step like" characteristics. Are there any ideas to what
> level such effects can be controlled
> during the run?
>
> RESPONSE : (Linear and sinusoidal drifts are the only type that I've
> seen. Higher orders could theoretically
> be present, but if they were I suppose they would
> become an issue for all experiments, not just ours.)
> "Step-like" changes in the packing factor or
> dilution factor have only been observed once in 700 hours
> of running the polarized target. It was
> immediately obvious from the change in polarization. If it
> occurs during this experiment, it would impact
> only a single pol/unpol cycle, which is either a 12 hour or
> 24 hour portion of data. This data would need to
> be either discarded or handled with care.
>
>
> In the proposal "consistency checks on measured cross section for
> each run" is mentioned.
> What precisely is meant? At what level it can be done for the
> proposed measurement? Please give
> more detail, especially on the precision of such test.
>
> RESPONSE : Typically we can monitor the unpolarized yields to the
> better than 1% level. Luminosity monitors
> installed around the beamline can be monitored
> to the ?? level (J.P.?)
>
>
> The other test mentioned in the proposal, where I would like to have
> some more comments on is "the
> measurements of dilution and packing factor - with carbon target "-
> what exactly is planed and which
> precision can be obtained? is it included in the beam time estimate?
>
> RESPONSE: The polarized target material is deuterated ammonia (ND_3).
> We determine the dilution factor by the ratio of
> simulated radiated rates on D to total
> rates. The pf is calculated by interpolating the
> ND3 measured rates between simulated
> rates for different packing factors, with the
> simulation calibrated by the measured rates
> on a carbon target of known thickness. The
> systematic uncertainty of this process
> is at the 4% level. It is important to note that
> the dilution factor is a scale factor so the
> uncertainty is an overall scale factor. We have 6
> hours assigned to this task in our overhead table 4.
> This is a relatively short time since all that is
> needed is to measure the unpolarized cross section
> from a carbon disk, and the rate is usually quite
> high.
>
>
> It would be interesting to see comparison of expected statistical
> errors in each bin with expected false
> asymmetries from time variation of beam and efficiency/acceptance.
>
> RESPONSE: We now have plots graphically showing the full systematic
> uncertainty, both from the normalization
> dependent factors and the possible drifts. The
> plots are shown in the technote.
>
>
> What are the arguments for proposed binning in x?
> the last bean is clear, as much data in this configuration as
> possible, but splitting of SHMS data taking
> in 3 intervals is not discussed from the optimalization point of view,
> it would be good to have it in the
> presentation.
>
> RESPONSE : (Hmm. Not sure how to answer this. Simple answer is that
> the points represent the largest
> spread in x that allows a reasonable overlap with
> HERMES in a reasonable amount of beam-time.
> Ellie has optimized to avoid large systematics
> from F1, and suppression of rates. )
>
>
>
> In general, also the authors call the measurement "ratio method" it
> is the cross section difference method
> as the two data sets are taken at different time. Advantage of "ratio
> method" can be fully used when two
> target cels are exposed at the same time and next order is reversed.
> Such configuration allows several
> additional cross checks, but requires two cell target.
>
> RESPONSE : We have examined a two cell configuration, and while it is
> attractive for the reason you point
> out, it was not clear at the time of the
> proposal submission that it significantly reduced the
> overall systematic uncertainty. We will
> continue to examine this option and are open to using
> it if we are convinced the systematic
> improvement is significant.
>
>
> test of Close-Kumano sum rule - it is very hard to do such test with
> limited coverage in x, may be some
> estimates of contribution measured/extrapolated can be done for
> specific models. For the models mentioned
> on page 17 - can one get some idea what would be the contribution in
> measured range?
>
> RESPONSE : Yes, this in an excellent suggestion. G. Miller and M.
> Sargian have provided us their curves.
> We need to integrate to see the contributions for
> x<0.15 and x>0.5. (Ellie, I think you have these
> now. Can you look into this?)
>
>
>
>
> _______________________________________________
> b1_ana mailing list
> b1_ana at jlab.org
> https://mailman.jlab.org/mailman/listinfo/b1_ana
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