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Dear Stan and all,
<div><br>
</div>
<div>just a quick comment about the 3.6 fb^-1 of integrated luminosity. The TDR was not quite exact at same places. Michael explained to me that we need twice 500h which corresponds to 3.6 fb^-1 in total. So we are not a factor 2 off, but just on track.</div>
<div><br>
</div>
<div>I would support Richard's idea of keeping running like it is, because changing too many parameters at a time or having many too small chunks of different datasets might not buy us anything in the end.</div>
<div><br>
</div>
<div>Cheers,</div>
<div><br>
</div>
<div>Alexander</div>
<div><br>
</div>
<div><br>
</div>
<div> <br>
<div>
<div>On Dec 20, 2012, at 4:31 PM, Belostotski, Stanislav wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div>Dear Richard, Michael and all,<br>
As indicated in the OLYMPUS TDR, in order to reach something better <br>
than 1 % statistical precision there must be collected 3.6 1/fb <br>
integrated luminosity for EACH beam species, which I am afraid not yet <br>
our case. Also, a data quality cut must unavoidably be applied, so <br>
we'll lose a (hopefully small) fraction of the data sample in addition. <br>
We can try to reduce the systematics as much as possible but can <br>
never jump over the statistical precision. So I would also vote for data <br>
collecting to the end of the run.<br>
Yet , I am still worrying about a systematics related to the beam <br>
energy variation which may affect the measured asymmetry. A naive MC <br>
estimation shows:<br>
beam instability of 1 MeV may result in 0.28% false asymmetry at <br>
scatt. angles >40 deg.<br>
Anyway, we should correct for the beam energy variation which is being <br>
monitored.<br>
To experimentally investigate that, it would take few hours provided<br>
that beam energy rearrangement, say to 2010 MeV, does not take much <br>
time.However if it takes much longer I withdraw this suggestion.The <br>
latter question must be addressed to Frank.<br>
With best regards StanB<br>
<br>
<br>
On 20.12.2012 14:52, Richard G Milner wrote:<br>
<blockquote type="cite">Dear Michael,<br>
</blockquote>
<blockquote type="cite">I must say that I have significant reservations about using the remaining<br>
</blockquote>
<blockquote type="cite">beamtime in the way you propose. They are as follows:<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">- I think it is well understood now that running with negative field<br>
</blockquote>
<blockquote type="cite">introduces<br>
</blockquote>
<blockquote type="cite">large, new systematics (Moller background, very different time to distance<br>
</blockquote>
<blockquote type="cite">relation etc.) beyond any which cancel in the super-ratio. This was a clever<br>
</blockquote>
<blockquote type="cite">idea but too naive. Most of our data have been taken with positive field. We<br>
</blockquote>
<blockquote type="cite">have to understand the acceptance to of order 1 % as is done in many cross<br>
</blockquote>
<blockquote type="cite">section experiments. Axel's recent work is promising that we can approach<br>
</blockquote>
<blockquote type="cite">this.<br>
</blockquote>
<blockquote type="cite">Also, we have taken some data already with negative field.<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">- Our proposal design was 3.6 inv fb. I think it is best if we take somewhat<br>
</blockquote>
<blockquote type="cite">more than that with positive field as this will allow us to put tighter cuts,<br>
</blockquote>
<blockquote type="cite">e.g. phi cut, than we had envisaged.<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">- Changing many things about the running in the holiday period where we (and<br>
</blockquote>
<blockquote type="cite">DESY) have a minimal crew available to deal with problems is risky.<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">So my vote is to continue the stable running of the experiment to acquire the<br>
</blockquote>
<blockquote type="cite">maximum amount of integrated luminosity with positive field in the remaining<br>
</blockquote>
<blockquote type="cite">time.<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">with best regards,<br>
</blockquote>
<blockquote type="cite">Richard<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">Quoting Michael Kohl <<a href="mailto:kohlm@jlab.org">kohlm@jlab.org</a>>:<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">Dear all,<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">we have collected 3.2 fb^-1 so far, almost close to the design<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">luminosity.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">For the 12-day addendum we should make a plan for a set of additional<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">measurements that could be helpful for the analysis.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">Here is my proposal for low-luminosity running:<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">-run all four configs (e+-,B+-) without shielding but with the intensity<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">reduced to optimze the noise, each for a day.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">E.g. reduce lumi by x10, expect ~3Hz elastics = 250k elastic events per<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">day -> 20 mA current / 0.2 sccm flow;<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">vary the magnetic field (100%, 75%, 50%, 25%) every six hours.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">Open up the trigger by reducing the prescale on the 3-of-4 trigger type<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">to max out the DAQ (<30-40% deadtime).<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">This would cost us four days of running.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">A data set with minimized noise can help us train and optimize the<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">reconstruction software, rather than using "noisy" high-luminosity data.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">A dataset with minimized moise in all four configs will show how the<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">cancelations in the ratio occur and will help us validate the MC. Varying<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">the magnetic field in addition will serve the same purpose. The statistics<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">will be good enough for the validation at forward angles, where also the<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">systematic effects on the single-polarity ratio were the largest.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">In the end we will need to be able to trust the MC for B+ at low epsilon.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">At low luminosity, a trigger which is more more open also allows to verify<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">TOF and trigger efficiencies, and to break any inefficiencies further down<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">as a function of channels, coordinates etc.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">We should start producing that set of measurements beginning on Saturday,<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">so that it could be finished by Wednesday. If it takes longer we still<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">have a few days left. Any final remaining days would be used to further<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">improve the statistics.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">Frank Brinker also would like to do another Touchek energy measurement,<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">probably on Dec 31 / Jan 1.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">If you have further ideas or wishes, please bring them up.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">Best regards<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"> Michael<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">+---------------------------------------------------------------------<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Dr. Michael Kohl, Assistant Professor and Staff Research Scientist<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Physics Department, Hampton University, Hampton, VA 23668<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Email: <a href="mailto:kohlm@jlab.org">kohlm@jlab.org</a><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Cell: +1-757-256-5122 (USA)<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">|<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">| Phone: +49-40-8998-6406, Cell: +49-171-101-1967<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">+---------------------------------------------------------------------<br>
</blockquote>
</blockquote>
<blockquote type="cite">
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<a href="mailto:winnebeck@mit.edu">winnebeck@mit.edu</a><br>
<br>
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Tel: +1-617-253-6580<br>
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